title: Covering many points with a small-area box

abstract:
  Let $P$ be a set of $n$ points in the plane. We show how to find, for a given
integer $k>0$, the smallest-area axis-parallel rectangle that covers $k$ points
of $P$ in $O(nk^2 \log n+ n\log^2 n)$ time. We also consider the problem of,
given a value $\alpha>0$, covering as many points of $P$ as possible with an
axis-parallel rectangle of area at most $\alpha$. For this problem we give a
probabilistic $(1-\varepsilon)$-approximation that works in near-linear time:
In $O((n/\varepsilon^4)\log^3 n \log (1/\varepsilon))$ time we find an
axis-parallel rectangle of area at most $\alpha$ that, with high probability,
covers at least $(1-\varepsilon)\mathrm{\kappa^*}$ points, where
$\mathrm{\kappa^*}$ is the maximum possible number of points that could be
covered.


title: Energy Cascade Rate In Compressible Fast And Slow Solar Wind Turbulence

abstract:
  Estimation of the energy cascade rate in the inertial range of solar wind
turbulence has been done so far mostly within the incompressible
magnetohydrodynamics (MHD) theory. Here, we go beyond that approximation to
include plasma compressibility using a reduced form of a recently derived exact
law for compressible, isothermal MHD turbulence. Using in-situ data from the
THEMIS/ARTEMIS spacecraft in the fast and slow solar wind, we investigate in
detail the role of the compressible fluctuations in modifying the energy
cascade rate with respect to the prediction of the incompressible MHD model. In
particular, we found that the energy cascade rate: i) is amplified particularly
in the slow solar wind; ii) exhibits weaker fluctuations in spatial scales,
which leads to a broader inertial range than the previous reported ones; iii)
has a power law scaling with the turbulent Mach number; iv) has a lower level
of spatial anisotropy. Other features of solar wind turbulence are discussed
along with their comparison with previous studies that used incompressible or
heuristic (non exact) compressible MHD models.


title: Magnetic Catalysis in the Higher-Order Quark Sigma Model

abstract:
  The effect of the higher-order mesonic interactions is investigated on the
chiral symmetry breaking in the presence of an external magnetic field. The
effective of higher-order mesonic potential is employed and is numerically
solved in the mean-field approximation. The chiral symmetry breaking increases
with increasing magnetic field. Two sets of free parameterization are
investigated on the magnetic catalysis. A comparison is discussed with the
original sigma model and other studies. The obtained results are included that
the higher-order mesonic interactions play an important role in the magnetic
catalysis.


title:
Dirac phase and replicating adiabaticity in isotropically moving wall
  confinement

abstract:
  Geometric phase in the wave function is important with regard to quantum
non-locality and adiabatic evolution. We study the confinement of a particle by
three-dimensional isotropically moving walls, of relevance to experimental
trapping techniques, via a proposed approach that explains the physical origin
of the geometric Dirac phase induced in the wave function. This phase depends
only on the relative rate of change of the spatial scale factor. The approach
also yields the class of external potentials that replicate adiabatic evolution
in finite time. As illustrative examples, we consider uniform and accelerating
walls, and the case where the Dirac phase is due to cosmic expansion.


title:
Revisiting Hammel et al. (1987): Does the shadowing property hold for
  modern computers?

abstract:
  Computational techniques are extensively applied in nonlinear science.
However, while the use of computers for research has been expressive, the
evaluation of numerical results does not grow in the same pace. Hammel et al.
(Journal of Complexity, 1987, 3(2), 136--145) were pioneers in the numerical
reliability field and have proved a theorem that a pseudo-orbit of a logistic
map is shadowed by a true orbit within a distance of $10^{-8}$ for $10^{7}$
iterates. But the simulation of the logistic map with less than 100 iterates
presents an error greater than $10^{-8}$ in a modern computer, performing a
test based on the concept of multiple pseudo-orbits and symbolic computing.


title: Gieseker conjecture for homogeneous spaces

abstract:
  We prove Gieseker conjecture for an homogeneous space $X$, saying that if $X$
has no non-trivial tame coverings then it has no non-trivial regular singular
$\mathscr{O}_X$-coherent $\mathscr{D}_{X/k}$-modules. In order to do so we
prove a K\"unneth formula for the regular singular stratified fundamental group
and a base change for Gauss-Manin stratifications in the non-proper case.


title:
Re-identification of Humans in Crowds using Personal, Social and
  Environmental Constraints

abstract:
  This paper addresses the problem of human re-identification across
non-overlapping cameras in crowds.Re-identification in crowded scenes is a
challenging problem due to large number of people and frequent occlusions,
coupled with changes in their appearance due to different properties and
exposure of cameras. To solve this problem, we model multiple Personal, Social
and Environmental (PSE) constraints on human motion across cameras. The
personal constraints include appearance and preferred speed of each individual
assumed to be similar across the non-overlapping cameras. The social influences
(constraints) are quadratic in nature, i.e. occur between pairs of individuals,
and modeled through grouping and collision avoidance. Finally, the
environmental constraints capture the transition probabilities between gates
(entrances / exits) in different cameras, defined as multi-modal distributions
of transition time and destination between all pairs of gates. We incorporate
these constraints into an energy minimization framework for solving human
re-identification. Assigning $1-1$ correspondence while modeling PSE
constraints is NP-hard. We present a stochastic local search algorithm to
restrict the search space of hypotheses, and obtain $1-1$ solution in the
presence of linear and quadratic PSE constraints. Moreover, we present an
alternate optimization using Frank-Wolfe algorithm that solves the convex
approximation of the objective function with linear relaxation on binary
variables, and yields an order of magnitude speed up over stochastic local
search with minor drop in performance. We evaluate our approach using
Cumulative Matching Curves as well $1-1$ assignment on several thousand frames
of Grand Central, PRID and DukeMTMC datasets, and obtain significantly better
results compared to existing re-identification methods.


title: Proper colouring Painter-Builder game

abstract:
  We consider the following two-player game, parametrised by positive integers
$n$ and $k$. The game is played between Painter and Builder, alternately taking
turns, with Painter moving first. The game starts with the empty graph on $n$
vertices. In each round Painter colours a vertex of her choice by one of the
$k$ colours and Builder claims an edge between two previously unconnected
vertices. Both players should maintain that during the game the graph admits a
proper $k$-colouring. The game ends if either all $n$ vertices have been
coloured, or Painter has no legal move. In the former case, Painter wins the
game, in the latter one Builder is the winner. We prove that the minimal number
of colours $k=k(n)$ allowing Painter's win is of logarithmic order in the
number of vertices $n$. Biased versions of the game are also considered.


title: Scale-dependent co-localization in a population of gyrotactic swimmers

abstract:
  We study the small scale clustering of gyrotactic swimmers transported by a
turbulent flow, when the intrinsic variability of the swimming parameters
within the population is considered. By means of extensive numerical
simulations, we find that the variety of the population introduces a
characteristic scale $R^*$ in its spatial distribution. At scales smaller than
$R^*$ the swimmers are homogeneously distributed, while at larger scales an
inhomogeneous distribution is observed with a fractal dimension close to what
observed for a monodisperse population characterized by mean parameters. The
scale $R^*$ depends on the dispersion of the population and it is found to
scale linearly with the standard deviation both for a bimodal and for a
Gaussian distribution. Our numerical results, which extend recent findings for
a monodisperse population, indicate that in principle it is possible to observe
small scale, fractal clustering in a laboratory experiment with gyrotactic
cells.


title: Proper Coloring of Geometric Hypergraphs

abstract:
  We study whether for a given planar family F there is an m such that any
finite set of points can be 3-colored such that any member of F that contains
at least m points contains two points with different colors. We conjecture that
if F is a family of pseudo-disks, then such an m exists. We prove this in the
special case when F is the family of all homothetic copies of a given convex
polygon. We also study the problem in higher dimensions.


title: Computations in $C_{pq}$-Bredon cohomology

abstract:
  In this paper, we compute the $RO(C_{pq})$-graded cohomology of
$C_{pq}$-orbits. We deduce that in all the cases the Bredon cohomology groups
are a function of the fixed point dimensions of the underlying virtual
representations. Further, when thought of as a Mackey functor, the same
independence result holds in almost all cases. This generalizes earlier
computations of Stong and Lewis for the group $C_p$.
  The computations of cohomology of orbits are used to prove a freeness
theorem. The analogous result for the group $C_p$ was proved by Lewis. We
demonstrate that certain complex projective spaces and complex Grassmannians
satisfy the freeness theorem.


title: Chromatic Numbers of Exact Distance Graphs

abstract:
  For any graph $G=(V,E)$ and positive integer $p$, the exact distance-$p$
graph $G^{[\natural p]}$ is the graph with vertex set $V$, which has an edge
between vertices $x$ and $y$ if and only if $x$ and $y$ have distance $p$ in
$G$. For odd $p$, Ne\v{s}et\v{r}il and Ossona de Mendez proved that for any
fixed graph class with bounded expansion, the chromatic number of $G^{[\natural
p]}$ is bounded by an absolute constant. Using the notion of generalised
colouring numbers, we give a much simpler proof for the result of
Ne\v{s}et\v{r}il and Ossona de Mendez, which at the same time gives
significantly better bounds. In particular, we show that for any graph $G$ and
odd positive integer $p$, the chromatic number of $G^{[\natural p]}$ is bounded
by the weak $(2p-1)$-colouring number of $G$. For even $p$, we prove that
$\chi(G^{[\natural p]})$ is at most the weak $(2p)$-colouring number times the
maximum degree. For odd $p$, the existing lower bound on the number of colours
needed to colour $G^{[\natural p]}$ when $G$ is planar is improved. Similar
lower bounds are given for $K_t$-minor free graphs.


title:
Measuring the non-asymptotic convergence of sequential Monte Carlo
  samplers using probabilistic programming

abstract:
  A key limitation of sampling algorithms for approximate inference is that it
is difficult to quantify their approximation error. Widely used sampling
schemes, such as sequential importance sampling with resampling and
Metropolis-Hastings, produce output samples drawn from a distribution that may
be far from the target posterior distribution. This paper shows how to
upper-bound the symmetric KL divergence between the output distribution of a
broad class of sequential Monte Carlo (SMC) samplers and their target posterior
distributions, subject to assumptions about the accuracy of a separate
gold-standard sampler. The proposed method applies to samplers that combine
multiple particles, multinomial resampling, and rejuvenation kernels. The
experiments show the technique being used to estimate bounds on the divergence
of SMC samplers for posterior inference in a Bayesian linear regression model
and a Dirichlet process mixture model.


title:
Rigorous numerics of tubular, conic, star-shaped neighborhoods of slow
  manifolds for fast-slow systems

abstract:
  We provide a rigorous numerical computation method to validate tubular
neighborhoods of normally hyperbolic slow manifolds with the explicit radii for
the fast-slow system \begin{equation*} \begin{cases} x' = f(x,y,\epsilon), and
y' =\epsilon g(x,y,\epsilon). & \end{cases} \end{equation*} Our main focus is
the validation of the continuous family of eigenpairs $\{\lambda_i(y;\epsilon),
u_i(y;\epsilon)\}_{i=1}^n$ of $f_x(h_\epsilon(y),y,\epsilon)$ over the slow
manifold $S_\epsilon = \{x = h_\epsilon(y)\}$ admitting the graph
representation. In order to obtain such a family, we apply the interval
Newton-like method with rigorous numerics. The validated family of eigenvectors
generates a vector bundle over $S_\epsilon$ determining normally hyperbolic
eigendirections rigorously. The generated vector bundle enables us to construct
a tubular neighborhood centered at slow manifolds with explicit radii.
Combining rate conditions for providing smoothness of center-(un)stable
manifolds, we can validate smooth tubular neighborhoods with diffeomorphic
family of affine change of coordinates, as well as several extensions such as
conic and star-shaped neighborhoods. Our procedure provides a systematic
construction of smooth neighborhoods of slow manifolds in an explicit range
$[0,\epsilon_0]$ of $\epsilon$ with rigorous numerics.


title: General Model for Light curves of Chromospherically Active Binary Stars

abstract:
  The starspots on the surface of many chromospherically active binary stars
concentrate on long--lived active longitudes separated by 180 degrees. The
activity shifts between these two longitudes, the "flip-flop" events, have been
observed in single stars like FK Comae and binary stars like $\sigma$
Geminorum. Recently, interferometry has revealed that ellipticity may at least
partly explain the "flip-flop" events in $\sigma$ Geminorum. This idea was
supported by the double peaked shape of the long--term mean light curve of this
star. Here, we show that the long--term mean light curves of fourteen
chromospherically active binaries follow a general model which explains the
connection betweenm orbital motion, starspot distribution changes, ellipticity
and \flip ~events. Surface differential rotation is probably weak in these
stars, because the interference of two constant period waves may explain the
observed light curve changes. These two constant periods are the active
longitude period $(P_{\mathrm{act}})$ and the orbital period
$(P_{\mathrm{orb}})$. We also show how to apply the same model to single stars,
where only the value of $P_{\mathrm{act}}$ is known. Finally, we present a
tentative interference hypothesis about the origin of magnetic fields in all
spectral types of stars.


title:
Design and low-temperature characterization of a tunable microcavity for
  diamond-based quantum networks

abstract:
  We report on the fabrication and characterization of a Fabry-Perot
microcavity enclosing a thin diamond membrane at cryogenic temperatures. The
cavity is designed to enhance resonant emission of single nitrogen-vacancy
centers by allowing spectral and spatial tuning while preserving the optical
properties observed in bulk diamond. We demonstrate cavity finesse at cryogenic
temperatures within the range of F = 4,000-12,000 and find a sub-nanometer
cavity stability. Modeling shows that coupling nitrogen-vacancy centers to
these cavities could lead to an increase of remote entanglement success rates
by three orders of magnitude.


title: A short note on groups in separably closed valued Fields

abstract:
  In this note we show that groups with definable generics in a separably
closed valued of finite imperfection degree can be embedded into groups
definable in their algebraic closure.


title:
Consensus Based Medical Image Segmentation Using Semi-Supervised
  Learning And Graph Cuts

abstract:
  Medical image segmentation requires consensus ground truth segmentations to
be derived from multiple expert annotations. A novel approach is proposed that
obtains consensus segmentations from experts using graph cuts (GC) and semi
supervised learning (SSL). Popular approaches use iterative Expectation
Maximization (EM) to estimate the final annotation and quantify annotator's
performance. Such techniques pose the risk of getting trapped in local minima.
We propose a self consistency (SC) score to quantify annotator consistency
using low level image features. SSL is used to predict missing annotations by
considering global features and local image consistency. The SC score also
serves as the penalty cost in a second order Markov random field (MRF) cost
function optimized using graph cuts to derive the final consensus label. Graph
cut obtains a global maximum without an iterative procedure. Experimental
results on synthetic images, real data of Crohn's disease patients and retinal
images show our final segmentation to be accurate and more consistent than
competing methods.


title:
Analysis of controlled Rabi flopping in a double rephasing photon echo
  scheme for quantum memories

abstract:
  A double rephasing photon echo is analyzed for inversion-free photon
echo-based quantum memories using controlled Rabi flopping, where the Rabi
flopping is used for phase control of atom coherence. Unlike the
rephasing-caused pi-phase shift in a single rephasing scheme, the control Rabi
flopping between the excited state and an auxiliary third state induces
coherence inversion. Thus, the absorptive photon echo in a double rephasing
scheme can be manipulated to be emissive via the controlled Rabi flopping. Here
we present a quantum coherence control of atom phases in a double rephasing
photon echo scheme for emissive photon echoes for quantum memory applications.


title: Asynchronous approach in the plane: A deterministic polynomial algorithm

abstract:
  In this paper we study the task of approach of two mobile agents having the
same limited range of vision and moving asynchronously in the plane. This task
consists in getting them in finite time within each other's range of vision.
The agents execute the same deterministic algorithm and are assumed to have a
compass showing the cardinal directions as well as a unit measure. On the other
hand, they do not share any global coordinates system (like GPS), cannot
communicate and have distinct labels. Each agent knows its label but does not
know the label of the other agent or the initial position of the other agent
relative to its own. The route of an agent is a sequence of segments that are
subsequently traversed in order to achieve approach. For each agent, the
computation of its route depends only on its algorithm and its label. An
adversary chooses the initial positions of both agents in the plane and
controls the way each of them moves along every segment of the routes, in
particular by arbitrarily varying the speeds of the agents. A deterministic
approach algorithm is a deterministic algorithm that always allows two agents
with any distinct labels to solve the task of approach regardless of the
choices and the behavior of the adversary. The cost of a complete execution of
an approach algorithm is the length of both parts of route travelled by the
agents until approach is completed. Let $\Delta$ and $l$ be the initial
distance separating the agents and the length of the shortest label,
respectively. Assuming that $\Delta$ and $l$ are unknown to both agents, does
there exist a deterministic approach algorithm always working at a cost that is
polynomial in $\Delta$ and $l$? In this paper, we provide a positive answer to
the above question by designing such an algorithm.


title:
Similar temperature scale for valence changes in Kondo lattices with
  different Kondo temperatures

abstract:
  The Kondo model predicts that both the valence at low temperatures and its
temperature dependence scale with the characteristic energy T_K of the Kondo
interaction. Here, we study the evolution of the 4f occupancy with temperature
in a series of Yb Kondo lattices using resonant X-ray emission spectroscopy. In
agreement with simple theoretical models, we observe a scaling between the
valence at low temperature and T_K obtained from thermodynamic measurements. In
contrast, the temperature scale T_v at which the valence increases with
temperature is almost the same in all investigated materials while the Kondo
temperatures differ by almost four orders of magnitude. This observation is in
remarkable contradiction to both naive expectation and precise theoretical
predictions of the Kondo model, asking for further theoretical work in order to
explain our findings. Our data exclude the presence of a quantum critical
valence transition in YbRh2Si2.


title: Non-volatile spin wave majority gate at the nanoscale

abstract:
  A spin wave majority fork-like structure with feature size of 40\,nm, is
presented and investigated, through micromagnetic simulations. The structure
consists of three merging out-of-plane magnetization spin wave buses and four
magneto-electric cells serving as three inputs and an output. The information
of the logic signals is encoded in the phase of the transmitted spin waves and
subsequently stored as direction of magnetization of the magneto-electric cells
upon detection. The minimum dimensions of the structure that produce an
operational majority gate are identified. For all input combinations, the
detection scheme employed manages to capture the majority phase result of the
spin wave interference and ignore all reflection effects induced by the
geometry of the structure.


title: On Rational Sets in Euclidean Spaces and Spheres

abstract:
  IFor a positive rational $l$, we define the concept of an $l$-elliptic and an
$l$-hyperbolic rational set in a metric space. In this article we examine the
existence of (i) dense and (ii) infinite $l$-hyperbolic and $l$-ellitpic
rationals subsets of the real line and unit circle. For the case of a circle,
we prove that the existence of such sets depends on the positivity of ranks of
certain associated elliptic curves. We also determine the closures of such sets
which are maximal in case they are not dense. In higher dimensions, we show the
existence of $l$-ellitpic and $l$-hyperbolic rational infinite sets in unit
spheres and Euclidean spaces for certain values of $l$ which satisfy a weaker
condition regarding the existence of elements of order more than two, than the
positivity of the ranks of the same associated elliptic curves. We also
determine their closures. A subset $T$ of the $k$-dimensional unit sphere $S^k$
has an antipodal pair if both $x,-x\in T$ for some $x\in S^k$. In this article,
we prove that there does not exist a dense rational set $T\subset S^2$ which
has an antipodal pair by assuming Bombieri-Lang Conjecture for surfaces of
general type. We actually show that the existence of such a dense rational set
in $S^k$ is equivalent to the existence of a dense $2$-hyperbolic rational set
in $S^k$ which is further equivalent to the existence of a dense 1-elliptic
rational set in the Euclidean space $\mathbb{R}^k$.


title:
Play With Me? Understanding and Measuring the Social Aspect of Casual
  Gaming

abstract:
  Social gaming is today a pervasive phenomenon. Driven by the advent of social
networks and the digitization of game distribution. In this paper the impact of
digitization and so-cial networks such as Facebook on digital games is
de-scribed and evaluated. This impact follows several vectors, including the
introduction of new game formats and extend-ing the traditional audiences for
games, which in turn has increased industrial revenue. The industry is in turn
shaped by new business model such as Free-to-Play, digital distri-bution and
the use of viral social features. These changes do not only appear
irreversible, but more importantly, play a part in shaping the future of
digital game design, notably for mobile devices. The paper presents new
knowledge from controlled live experiments from a casual social game across
Facebook and mobile platforms, finding positive re-turns by adding social
gameplay features. This suggests that not only social network games, but also
casual mobile games can benefit from deeper social gameplay mechanics. Given
the impact of social features on gameplay, Game An-alytics will need to evolve
to be able to handle requirements that arise from the introduction of social
features, e.g. how to measure engagement against social features and shaping
organic and viral spreading of a game.


title:
A cooperative approach among methods for photometric redshifts
  estimation: an application to KiDS data

abstract:
  Photometric redshifts (photo-z's) are fundamental in galaxy surveys to
address different topics, from gravitational lensing and dark matter
distribution to galaxy evolution. The Kilo Degree Survey (KiDS), i.e. the ESO
public survey on the VLT Survey Telescope (VST), provides the unprecedented
opportunity to exploit a large galaxy dataset with an exceptional image quality
and depth in the optical wavebands. Using a KiDS subset of about 25,000
galaxies with measured spectroscopic redshifts, we have derived photo-z's using
i) three different empirical methods based on supervised machine learning, ii)
the Bayesian Photometric Redshift model (or BPZ), and iii) a classical SED
template fitting procedure (Le Phare). We confirm that, in the regions of the
photometric parameter space properly sampled by the spectroscopic templates,
machine learning methods provide better redshift estimates, with a lower
scatter and a smaller fraction of outliers. SED fitting techniques, however,
provide useful information on the galaxy spectral type which can be effectively
used to constrain systematic errors and to better characterize potential
catastrophic outliers. Such classification is then used to specialize the
training of regression machine learning models, by demonstrating that a hybrid
approach, involving SED fitting and machine learning in a single collaborative
framework, can be effectively used to improve the accuracy of photo-z
estimates.


title:
EMC Regulations and Spectral Constraints for Multicarrier Modulation in
  PLC

abstract:
  This paper considers Electromagnetic Compatibility (EMC) aspects in the
context of Power Line Communication (PLC) systems. It offers a complete
overview of both narrow band PLC and broad band PLC EMC norms. How to interpret
and translate such norms and measurement procedures into typical constraints
used by designers of communication systems, is discussed. In particular, the
constraints to the modulated signal spectrum are considered and the ability of
pulse shaped OFDM (PS-OFDM), used in most of the PLC standards as IEEE P1901
and P1901.2, to fulfill them is analyzed. In addition, aiming to improve the
spectrum management ability, a novel scheme named Pulse Shaped Cyclic Block
Filtered Multitone modulation (PS-CB-FMT) is introduced and compared to
PS-OFDM. It is shown that, PS-CB-FMT offers better ability to fulfill the norms
which translates in higher system capacity.


title:
Efficient use of paired spectrum bands through TDD small cell
  deployments

abstract:
  Traditionally, wireless cellular systems have been designed to operate in
Frequency Division Duplexing (FDD) paired bands that allocates the same amount
of spectrum for both downlink (DL) and uplink (UL) communication. Such design
is very convenient under symmetric DL/UL traffic conditions, as it used to be
the case when the voice transmission was the predominant service. However, with
the overwhelming advent of data services, bringing along large asymmetries
between DL and UL, the conventional FDD solution becomes inefficient. In this
regard, flexible duplexing concepts aim to derive procedures for improving the
spectrum utilization, by adjusting resources to the actual traffic demand. In
this work we review these concepts and propose the use of unpaired Time
Division Duplexing (TDD) spectrum on the unused resources for small eNBs
(SeNB), so that user equipment (UEs) associated to those SeNB could be served
either in DL or UL. This proposal alleviates the saturated DL in FDD-based
system through user offloading towards the TDD-based system. The flexible
duplexing concept is analyzed from three points of view: a) regulation, b) Long
Term Evolution (LTE)standardization, and c) technical solutions.


title:
Exotic surface states in hybrid structures of topological insulators and
  Weyl semimetals

abstract:
  Topological insulators (TIs) and Weyl semimetals (WSMs) are two realizations
of topological matter usually appearing separately in nature. However, they are
directly related to each other via a topological phase transition. In this
paper, we investigate the question whether these two topological phases can
exist together at the same time, with a combined, hybrid surface state at the
joint boundaries. We analyze effective models of a 3D TI and an inversion
symmetric WSM and couple them in a way that certain symmetries, like inversion,
are preserved. A tunnel coupling approach enables us to obtain the hybrid
surface state Hamiltonian analytically. This offers the possibility of a
detailed study of its dispersion relation depending on the investigated
couplings. For spin-symmetric coupling, we find that two Dirac nodes can emerge
out of the combination of a single Dirac node and a Fermi arc. For
spin-asymmetric coupling, the dispersion relation is gapped and the former
Dirac node gets spin-polarized. We propose different experimental realization
of the hybrid system, including compressively strained HgTe as well as
heterostructures of TI and WSM materials.


title:
Deep Multi-scale Convolutional Neural Network for Dynamic Scene
  Deblurring

abstract:
  Non-uniform blind deblurring for general dynamic scenes is a challenging
computer vision problem as blurs arise not only from multiple object motions
but also from camera shake, scene depth variation. To remove these complicated
motion blurs, conventional energy optimization based methods rely on simple
assumptions such that blur kernel is partially uniform or locally linear.
Moreover, recent machine learning based methods also depend on synthetic blur
datasets generated under these assumptions. This makes conventional deblurring
methods fail to remove blurs where blur kernel is difficult to approximate or
parameterize (e.g. object motion boundaries). In this work, we propose a
multi-scale convolutional neural network that restores sharp images in an
end-to-end manner where blur is caused by various sources. Together, we present
multi-scale loss function that mimics conventional coarse-to-fine approaches.
Furthermore, we propose a new large-scale dataset that provides pairs of
realistic blurry image and the corresponding ground truth sharp image that are
obtained by a high-speed camera. With the proposed model trained on this
dataset, we demonstrate empirically that our method achieves the
state-of-the-art performance in dynamic scene deblurring not only
qualitatively, but also quantitatively.


title: Improved upper bound on A(18,8)

abstract:
  For nonnegative integers $n$ and $d$, let $A(n,d)$ be the maximum cardinality
of a binary code of length $n$ and minimum distance at least $d$. We consider a
slight sharpening of the semidefinite programming bound of Gijswijt, Mittelmann
and Schrijver, and obtain that $A(18,8)\leq 70$.


title: Model-based Adversarial Imitation Learning

abstract:
  Generative adversarial learning is a popular new approach to training
generative models which has been proven successful for other related problems
as well. The general idea is to maintain an oracle $D$ that discriminates
between the expert's data distribution and that of the generative model $G$.
The generative model is trained to capture the expert's distribution by
maximizing the probability of $D$ misclassifying the data it generates.
Overall, the system is \emph{differentiable} end-to-end and is trained using
basic backpropagation. This type of learning was successfully applied to the
problem of policy imitation in a model-free setup. However, a model-free
approach does not allow the system to be differentiable, which requires the use
of high-variance gradient estimations. In this paper we introduce the Model
based Adversarial Imitation Learning (MAIL) algorithm. A model-based approach
for the problem of adversarial imitation learning. We show how to use a forward
model to make the system fully differentiable, which enables us to train
policies using the (stochastic) gradient of $D$. Moreover, our approach
requires relatively few environment interactions, and fewer hyper-parameters to
tune. We test our method on the MuJoCo physics simulator and report initial
results that surpass the current state-of-the-art.


title:
Non-Sequential Double Recombination High Harmonic Generation in
  Molecular-like Systems

abstract:
  We present a study of non-sequential double recombination (NSDR) high
harmonic generation (HHG) in a molecular-like system. Using a Coulomb-corrected
three-step model we are able to classically describe the observed NSDR HHG
cutoffs precisely for all internuclear distances showing an intrinsic
dependence on the location of the nuclei in the NSDR HHG process originating
partly from the strong electron correlation in the NSDR HHG process. This
dependence modifies the classically allowed return energies which in return
changes the cutoffs observed in the HHG spectra. We also observe that the NSDR
HHG signal changes its character for internuclear distances of $R\gtrsim 8-9$
a.u. which is proposed to stem from a change in the charge transfer dynamics
within the molecule. For large internuclear distances of $R\gtrsim 13$ a.u. we
observe a clear signature of the point of emission for the first electron
emitted in the NSDR HHG signal and we also see signs of molecular exchange
paths contributing to the HHG spectrum for these internuclear distances.


title:
Information Dimension of Stochastic Processes on Networks: Relating
  Entropy Production to Spectral Properties

abstract:
  We consider discrete stochastic processes, modeled by classical master
equations, on networks. The temporal growth of the lack of information about
the system is captured by its non-equilibrium entropy, defined via the
transition probabilities between different nodes of the network. We derive a
relation between the entropy and the spectrum of the master equation's transfer
matrix. Our findings indicate that the temporal growth of the entropy is
proportional to the logarithm of time if the spectral density shows scaling. In
analogy to chaos theory, the proportionality factor is called (stochastic)
information dimension and gives a global characterization of the dynamics on
the network. These general results are corroborated by examples of regular and
of fractal networks.


title: A flat Higgs bundle structure on the complexified K\"ahler cone

abstract:
  We shall construct a natural Higgs bundle structure on the complexified
K\"ahler cone of a compact K\"ahler manifold, which can be seen as an analogy
of the classical Higgs bundle structure associated to a variation of Hodge
structure. In the proof of the flat-ness of our Higgs bundle, we find a
commutator identity that can be used to decode the variational properties of
the polarized Hodge-Lefschetz module structure on the fibres of our Higgs
bundle. Thus we can use a generalized version of Lu's Hodge metric to study the
curvature property of the complexified K\"ahler cone. In particular, it implies
that the above Hodge metric defines a K\"ahler metric on the complexified
K\"ahler cone with negative holomorphic sectional curvature, which can be seen
as a new result on Wilson's conjecture.


title: Fusion of Range and Thermal Images for Person Detection

abstract:
  Detecting people in images is a challenging problem. Differences in pose,
clothing and lighting, along with other factors, cause a lot of variation in
their appearance. To overcome these issues, we propose a system based on fused
range and thermal infrared images. These measurements show considerably less
variation and provide more meaningful information. We provide a brief
introduction to the sensor technology used and propose a calibration method.
Several data fusion algorithms are compared and their performance is assessed
on a simulated data set. The results of initial experiments on real data are
analyzed and the measurement errors and the challenges they present are
discussed. The resulting fused data are used to efficiently detect people in a
fixed camera set-up. The system is extended to include person tracking.


title: Saliency Driven Image Manipulation

abstract:
  Have you ever taken a picture only to find out that an unimportant background
object ended up being overly salient? Or one of those team sports photos where
your favorite player blends with the rest? Wouldn't it be nice if you could
tweak these pictures just a little bit so that the distractor would be
attenuated and your favorite player will stand-out among her peers?
Manipulating images in order to control the saliency of objects is the goal of
this paper. We propose an approach that considers the internal color and
saliency properties of the image. It changes the saliency map via an
optimization framework that relies on patch-based manipulation using only
patches from within the same image to achieve realistic looking results.
Applications include object enhancement, distractors attenuation and background
decluttering. Comparing our method to previous ones shows significant
improvement, both in the achieved saliency manipulation and in the realistic
appearance of the resulting images.


title: Commuting involution graphs for $\tilde C_n$

abstract:
  In this article we consider commuting graphs of involution conjugacy classes
in the affine Weyl group of type $\tilde C_n$. We show that where the graph is
connected the diameter is at most $n+2$.


title:
Procedures for the relative calibration of the SiPM gain on ASTRI SST-2M
  camera

abstract:
  ASTRI SST-2M is one of the prototypes of the small size class of telescopes
proposed for the Cherenkov Telescope Array. Its optical design is based on a
dual-mirror Schwarzschild-Couder configuration, and the camera is composed by a
matrix of monolithic multipixel silicon photomultipliers managed by ad-hoc
tailored front-end electronics. This paper describes the procedures for the
gain calibration on the ASTRI SST-2M. Since the SiPM gain depends on the
operative voltage and the temperature, we adjust the operative voltages for all
sensors to have equal gains at a reference temperature. We then correct gain
variations caused by temperature changes by adjusting the operating voltage of
each sensor. For that purpose the SiPM gain dependence on operating voltage and
on temperature have been measured. In addition, we present the calibration
procedures and the results of the experimental measurements to evaluate, for
each pixel, the parameters necessary to make the trigger uniform over the whole
focal plane.


title:
Field emission: the theoretical link between voltage loss, reduction in
  field enhancement factor, and Fowler-Nordheim-plot saturation

abstract:
  With a large-area field electron emitter, when an individual post-like
emitter is sufficiently resistive, and current through it sufficiently large,
then voltage loss occurs along it. This Letter provides a simple analytical and
conceptual demonstration that this voltage loss is directly and inextricably
linked to a reduction in the field enhancement factor (FEF) at the post apex. A
formula relating apex-FEF reduction to this voltage loss was obtained in the
paper by E. Minoux, O. Groening, K. B. K. Teo, S. H. Dalal, L. Gangloff, J.-P.
Schnell, L. Hudanski, I. Y. Y. Bu., P. Vincent, P. Legagneux, G. A. J.
Amaratunga, and W. I. Milne [Nano Lett. 5, 2135 (2005)], by fitting to
numerical results from a Laplace solver. This Letter derives the same formula
analytically, by using a "floating sphere" model. The analytical proof brings
out the underlying physics more clearly, and shows that the effect is a general
phenomenon, related to reduction in the magnitude of the surface charge in the
most protruding parts of an emitter. Voltage-dependent FEF-reduction is one
cause of "saturation" in Fowler-Nordheim plots. Another is a voltage-divider
effect, due to measurement-circuit resistance. An integrated theory of both
effects is presented. Both together, or either by itself, can cause saturation.
Experimentally, if saturation occurs but voltage loss is small (< 20 V, say),
then saturation is more probably due to FEF-reduction than voltage division. In
this case, existing treatments of electrostatic interaction ("shielding")
between closely spaced emitters may need modification. Other putative causes of
saturation exist, so the present theory is a partial story. Its extension seems
possible, and could lead to a more general physical understanding of the causes
of FN-plot saturation.


title: Microscopic Study of ${}^1{S_0}$ Superfluidity in Dilute Neutron Matter

abstract:
  Singlet $S$-wave superfluidity of dilute neutron matter is studied within the
correlated BCS method, which takes into account both pairing and short-range
correlations. First, the equation of state (EOS) of normal neutron matter is
calculated within the Correlated Basis Function (CBF) method in lowest cluster
order using the ${}^1{S_0}$ and ${}^3P$ components of the Argonne $V_{18}$
potential, assuming trial Jastrow-type correlation functions. The ${}^1{S_0}$
superfluid gap is then calculated with the corresponding component of the
Argonne $V_{18}$ potential and the optimally determined correlation functions.
The dependence of our results on the chosen forms for the correlation functions
is studied, and the role of the $P$-wave channel is investigated. Where
comparison is meaningful, the values obtained for the ${}^1{S_0}$ gap within
this simplified scheme are consistent with the results of similar and more
elaborate microscopic methods.

categories: nucl-th astro-ph.HE cond-mat.quant-gas cond-mat.supr-con


title:
Tensor-Based Fusion of EEG and FMRI to Understand Neurological Changes
  in Schizophrenia

abstract:
  Neuroimaging modalities such as functional magnetic resonance imaging (fMRI)
and electroencephalography (EEG) provide information about neurological
functions in complementary spatiotemporal resolutions; therefore, fusion of
these modalities is expected to provide better understanding of brain activity.
In this paper, we jointly analyze fMRI and multi-channel EEG signals collected
during an auditory oddball task with the goal of capturing brain activity
patterns that differ between patients with schizophrenia and healthy controls.
Rather than selecting a single electrode or matricizing the third-order tensor
that can be naturally used to represent multi-channel EEG signals, we preserve
the multi-way structure of EEG data and use a coupled matrix and tensor
factorization (CMTF) model to jointly analyze fMRI and EEG signals. Our
analysis reveals that (i) joint analysis of EEG and fMRI using a CMTF model can
capture meaningful temporal and spatial signatures of patterns that behave
differently in patients and controls, and (ii) these differences and the
interpretability of the associated components increase by including multiple
electrodes from frontal, motor and parietal areas, but not necessarily by
including all electrodes in the analysis.


title: Template Matching with Deformable Diversity Similarity

abstract:
  We propose a novel measure for template matching named Deformable Diversity
Similarity -- based on the diversity of feature matches between a target image
window and the template. We rely on both local appearance and geometric
information that jointly lead to a powerful approach for matching. Our key
contribution is a similarity measure, that is robust to complex deformations,
significant background clutter, and occlusions. Empirical evaluation on the
most up-to-date benchmark shows that our method outperforms the current
state-of-the-art in its detection accuracy while improving computational
complexity.


title: Biphoton states in correlated turbulence

abstract:
  The effect of turbulence on a pair of photons propagating together through
the same medium is analyzed. The behavior is compared to the case where these
photons propagate separately through different turbulent media. The analysis is
done with a multiple phase screen approach, by deriving and solving an
infinitesimal propagation equation. We apply these results to the case where
the initial photons are entangled in their spatial degrees of freedom with the
aid of spontaneous parametric down-conversion. It is found that for this input
state, the decay of entanglement in correlated media under the weak
scintillation approximation is quicker than in uncorrelated media. Beyond the
weak scintillation approximation, the entanglement in correlated media decays
slower when it is close to zero --- approaching zero asymptotically as a
function of scintillation strength. This is contrary to the case in
uncorrelated media where entanglement becomes zero at a finite scintillation
strength.


title: Fast Adaptation in Generative Models with Generative Matching Networks

abstract:
  Despite recent advances, the remaining bottlenecks in deep generative models
are necessity of extensive training and difficulties with generalization from
small number of training examples. We develop a new generative model called
Generative Matching Network which is inspired by the recently proposed matching
networks for one-shot learning in discriminative tasks. By conditioning on the
additional input dataset, our model can instantly learn new concepts that were
not available in the training data but conform to a similar generative process.
The proposed framework does not explicitly restrict diversity of the
conditioning data and also does not require an extensive inference procedure
for training or adaptation. Our experiments on the Omniglot dataset demonstrate
that Generative Matching Networks significantly improve predictive performance
on the fly as more additional data is available and outperform existing state
of the art conditional generative models.


title: A controlled ac Stark echo for quantum memories

abstract:
  A quantum memory protocol of controlled ac Stark echoes (CASE) based on a
double rephasing photon echo scheme via controlled Rabi flopping is proposed. A
double rephasing scheme of photon echoes inherently satisfies the no-population
inversion requirement for quantum memories, but the resultant absorptive echo
has been a fundamental problem. In the present studies, firstly, the first echo
in the double rephasing scheme is dynamically controlled not to affect the
second echo by using unbalanced ac Stark shifts. Secondly, a control Rabi pulse
coherently manipulates the second echo to be emissive via controlled coherence
conversion. Owing to far-off resonance of ac Stark fields, the present protocol
can be applied for wavelength-selective dynamic control of quantum memories in
real time for erasing, buffering, and multiplexing.


title:
The logarithmic Choquard equation: sharp asymptotics and nondegeneracy
  of the groundstate

abstract:
  We derive the asymptotic decay of the unique positive, radially symmetric
solution to the logarithmic Choquard equation $$ - \Delta u + a u = \frac{1}{2
\pi} \Bigl[\ln \frac{1}{|x|}* |u|^2 \Bigr] \ u \qquad \text{in $\mathbb{R}^2$}
$$ and we establish its nondegeneracy. For the corresponding three-dimensional
problem, the nondegeneracy property of the positive ground state to the
Choquard equation was proved by E. Lenzmann (Analysis & PDE, 2009).


title:
Generalized Exponential smoothing in prediction of hierarchical time
  series

abstract:
  Shang and Hyndman (2017) proposed a grouped functional time series
forecasting approach as a combination of individual forecasts obtained using
generalized least squares method. We modify their methodology using generalized
exponential smoothing technique for the most disaggregated functional time
series in order to obtain more robust predictor. We discuss some properties of
our proposals basing on results obtained via simulation studies and analysis of
real data related to a prediction of a demand for electricity in Australia in
2016.


title: Dense gas in low-metallicity galaxies

abstract:
  Stars form out of the densest parts of molecular clouds. Far-IR emission can
be used to estimate the Star Formation Rate (SFR) and high dipole moment
molecules, typically HCN, trace the dense gas. A strong correlation exists
between HCN and Far-IR emission, with the ratio being nearly constant, over a
large range of physical scales. A few recent observations have found HCN to be
weak with respect to the Far-IR and CO in subsolar metallicity (low-Z) objects.
We present observations of the Local Group galaxies M33, IC10, and NGC6822 with
the IRAM 30meter and NRO 45m telescopes, greatly improving the sample of low-Z
galaxies observed. HCN, HCO$^+$, CS, C$_2$H, and HNC have been detected.
Compared to solar metallicity galaxies, the Nitrogen-bearing species are weak
(HCN, HNC) or not detected (CN, HNCO, N$_2$H$^+$) relative to Far-IR or CO
emission. HCO$^+$ and C$_2$H emission is normal with respect to CO and Far-IR.
While $^{13}$CO is the usual factor 10 weaker than $^{12}$CO, C$^{18}$O
emission was not detected down to very low levels. Including earlier data, we
find that the HCN/HCO$^+$ ratio varies with metallicity (O/H) and attribute
this to the sharply decreasing Nitrogen abundance. The dense gas fraction,
traced by the HCN/CO and HCO$^+$/CO ratios, follows the SFR but in the low-Z
objects the HCO$^+$ is much easier to measure. Combined with larger and smaller
scale measurements, the HCO$^+$ line appears to be an excellent tracer of dense
gas and varies linearly with the SFR for both low and high metallicities.


title: K\"ahler geometry on Hurwitz spaces

abstract:
  We study the K\"ahler geometry of the classical Hurwitz space
$\mathcal{H}^{n,b}$ of simple branched coverings of the Riemann sphere
$\mathbb{P}^1$ by compact hyperbolic Riemann surfaces. A generalized
Weil-Petersson metric on the Hurwitz space was recently introduced.
Deformations of simple branched coverings fit into the more general framework
of Horikawa's deformation theory of holomorphic maps, which we equip with
distinguished representatives in the presence of hermitian metrics. In the
article we will investigate the curvature of the generalized Weil-Petersson
K\"ahler metric on the Hurwitz space.


title: Towards computer-assisted understanding of dynamics in symphonic music

abstract:
  Many people enjoy classical symphonic music. Its diverse instrumentation
makes for a rich listening experience. This diversity adds to the conductor's
expressive freedom to shape the sound according to their imagination. As a
result, the same piece may sound quite differently from one conductor to
another. Differences in interpretation may be noticeable subjectively to
listeners, but they are sometimes hard to pinpoint, presumably because of the
acoustic complexity of the sound. We describe a computational model that
interprets dynamics---expressive loudness variations in performances---in terms
of the musical score, highlighting differences between performances of the same
piece. We demonstrate experimentally that the model has predictive power, and
give examples of conductor ideosyncrasies found by using the model as an
explanatory tool. Although the present model is still in active development, it
may pave the road for a consumer-oriented companion to interactive classical
music understanding.


title:
Majorana fermions in topological insulator nanowires: from single
  superconducting nanowires to Josephson junctions

abstract:
  Signatures of Majorana fermion bound states in one-dimensional topological
insulator (TI) nanowires with proximity effect induced superconductivity are
studied. The phase diagram and energy spectra are calculated for single TI
nanowires and it is shown that the nanowires can be in the topological
invariant phases of winding numbers $W=0, \pm 1$, and $\pm 2$ corresponding to
the cases with zero, one and two pairs of Majorana fermions in the single TI
nanowires. It is also shown that the topological winding numbers, i.e., the
numbers of pairs of Majorana fermions in the TI nanowires can be extracted from
the transport measurements of a Josephson junction device made from two TI
nanowires, while the sign in the winding numbers can be extracted using a
superconducting quantum interference device (SQUID) setup.


title: RF Measurements of the New TOTEM Roman Pot

abstract:
  The TOTEM experiment has been designed to measure the total proton-proton
cross section and to study the elastic and diffractive scattering at the LHC
energy. The measurement requires detecting protons at distances as small as 1
mm from the beam center: TOTEM uses Roman Pots, movable beam pipe insertions,
hosting silicon detectors. In the first period of LHC operation no relevant
problems were detected with Roman Pots retracted or inserted during special
runs. However, when operating the LHC with high intensity beams, impedance
induced heating has been observed during the Roman Pots insertion. In order to
be compatible with the higher LHC beam current foreseen after the LS1, a new
version of the Roman Pot has been proposed and optimized with respect to the
beam coupling impedance. In this work we present the bench impedance
measurements carried out on the new Roman Pot prototype. Single and double wire
measurements, as well as probe measurements, were performed in order to detect
possible harmful resonant modes. The laboratory setup has been as well
simulated with the help of CST Particle Studio in order to benchmark the
measurement results. Measurements and simulations are in close agreement
confirming the equipment compatibility with the LHC requirements for safe
operation.


title: Finite presentation is a Morita invariant property

abstract:
  We prove that the property of an algebra to be finitely presented is Morita
invariant.


title:
Full diversity sets of unitary matrices from orthogonal sets of
  idempotents

abstract:
  Orthogonal sets of idempotents are used to design sets of unitary matrices,
known as constellations, such that the modulus of the determinant of the
difference of any two distinct elements is greater than $0$. It is shown that
unitary matrices in general are derived from orthogonal sets of idempotents
reducing the design problem to a construction problem of unitary matrices from
such sets. The quality of the constellations constructed in this way and the
actual differences between the unitary matrices can be determined algebraically
from the idempotents used.
  This has applications to the design of unitary space time constellations.


title: A Functional Regression approach to Facial Landmark Tracking

abstract:
  Linear regression is a fundamental building block in many face detection and
tracking algorithms, typically used to predict shape displacements from image
features through a linear mapping. This paper presents a Functional Regression
solution to the least squares problem, which we coin Continuous Regression,
resulting in the first real-time incremental face tracker. Contrary to prior
work in Functional Regression, in which B-splines or Fourier series were used,
we propose to approximate the input space by its first-order Taylor expansion,
yielding a closed-form solution for the continuous domain of displacements. We
then extend the continuous least squares problem to correlated variables, and
demonstrate the generalisation of our approach. We incorporate Continuous
Regression into the cascaded regression framework, and show its computational
benefits for both training and testing. We then present a fast approach for
incremental learning within Cascaded Continuous Regression, coined iCCR, and
show that its complexity allows real-time face tracking, being 20 times faster
than the state of the art. To the best of our knowledge, this is the first
incremental face tracker that is shown to operate in real-time. We show that
iCCR achieves state-of-the-art performance on the 300-VW dataset, the most
recent, large-scale benchmark for face tracking.


title: The interaction of hydrodynamic shocks with self-gravitating clouds

abstract:
  We describe the results of 3D simulations of the interaction of hydrodynamic
shocks with Bonnor-Ebert spheres performed with an Adaptive Mesh Refinement
code. The calculations are isothermal and the clouds are embedded in a medium
in which the sound speed is either four or ten times that in the cloud. The
strengths of the shocks are such that they induce gravitational collapse in
some cases and not in others and we derive a simple estimate for the shock
strength required for this to occur. These results are relevant to dense cores
and Bok globules in star forming regions subjected to shocks produced by
stellar feedback.


title: Periodic Reeb orbits on prequantization bundles

abstract:
  In this paper, we prove that every graphical hypersurface in a
prequantization bundle over a symplectic manifold $M$, pinched between two
circle bundles whose ratio of radii is less than $\sqrt{2}$ carries either one
short simple periodic orbit or carries at least $\operatorname{cuplength}(M)+1$
simple periodic Reeb orbits.


title:
Metric space approach to potentials and its relevance to density
  functional theory

abstract:
  External potentials play a crucial role in modelling quantum systems, since,
for a given inter- particle interaction, they define the system Hamiltonian. We
use the metric space approach to quantum mechanics to derive, from the energy
conservation law, two natural metrics for potentials. We show that these
metrics are well defined for physical potentials, regardless of whether the
system is in an eigenstate or if the potential is bounded. In addition, we
discuss the gauge freedom of potentials and how to ensure that the metrics
preserve physical relevance. Our metrics for potentials, together with the
metrics for wavefunctions and densities from [I. D'Amico, J. P. Coe, V. V.
Franca, and K. Capelle, Phys. Rev. Lett. 106, 050401 (2011)] paves the way for
a comprehensive study of the two fundamental theorems of Density Functional
Theory. We explore these by analysing two many- body systems for which the
related exact Kohn-Sham systems can be derived. First we consider the
information provided by each of the metrics, and we find that the density
metric performs best in distinguishing two many-body systems. Next we study for
the systems at hand the one-to-one relationships among potentials, ground state
wavefunctions, and ground state densities defined by the Hohenberg-Kohn theorem
as relationships in metric spaces. We find that, in metric space, these
relationships are monotonic and incorporate regions of linearity, at least for
the systems considered. Finally, we use the metrics for wavefunctions and
potentials in order to assess quantitatively how close the many-body and
Kohn-Sham systems are: We show that, at least for the systems analysed, both
metrics provide a consistent picture, and for large regions of the parameter
space the error in approximating the many-body wavefunction with the Kohn-Sham
wavefunction lies under a threshold of 10%.


title: On the last stable orbit around rapidly rotating neutron stars

abstract:
  We compute the binding energy and angular momentum of a test-particle at the
last stable circular orbit (LSO) on the equatorial plane around a general
relativistic, rotating neutron star (NS). We present simple, analytic, but
accurate formulas for these quantities that fit the numerical results and which
can be used in several astrophysical applications. We demonstrate the accuracy
of these formulas for three different equations of state (EOS) based on nuclear
relativistic mean-field theory models and argue that they should remain still
valid for any NS EOS that satisfy current astrophysical constraints. We compare
and contrast our numerical results with the corresponding ones for the Kerr
metric characterized by the same mass and angular momentum.


title:
Scalable smoothing strategies for a geometric multigrid method for the
  immersed boundary equations

abstract:
  The immersed boundary (IB) method is a widely used approach to simulating
fluid-structure interaction (FSI). Although explicit versions of the IB method
can suffer from severe time step size restrictions, these methods remain
popular because of their simplicity and generality. In prior work (Guy et al.,
Adv Comput Math, 2015), some of us developed a geometric multigrid
preconditioner for a stable semi-implicit IB method under Stokes flow
conditions; however, this solver methodology used a Vanka-type smoother that
presented limited opportunities for parallelization. This work extends this
Stokes-IB solver methodology by developing smoothing techniques that are
suitable for parallel implementation. Specifically, we demonstrate that an
additive version of the Vanka smoother can yield an effective multigrid
preconditioner for the Stokes-IB equations, and we introduce an efficient Schur
complement-based smoother that is also shown to be effective for the Stokes-IB
equations. We investigate the performance of these solvers for a broad range of
material stiffnesses, both for Stokes flows and flows at nonzero Reynolds
numbers, and for thick and thin structural models. We show here that linear
solver performance degrades with increasing Reynolds number and material
stiffness, especially for thin interface cases. Nonetheless, the proposed
approaches promise to yield effective solution algorithms, especially at lower
Reynolds numbers and at modest-to-high elastic stiffnesses.


title: Table-top laser-based proton acceleration in nanostructured targets

abstract:
  The interaction of ultrashort, high intensity laser pulses with thin foil
targets leads to ion acceleration on the target rear surface. To make this ion
source useful for applications, it is important to optimize the transfer of
energy from the laser into the accelerated ions. One of the most promising ways
to achieve this consists in engineering the target front by introducing
periodic nanostructures.
  In this paper, the effect of these structures on ion acceleration is studied
analytically and with multi-dimensional particle-in-cell simulations. We
assessed the role of the structure shape, size, and the angle of laser
incidence for obtaining the efficient energy transfer. Local control of
electron trajectories is exploited to maximise the energy delivered into the
target. Based on our numerical simulations, we propose a precise range of
parameters for fabrication of nanostructured targets, which can increase the
energy of the accelerated ions without requiring a higher laser intensity.


title:
Total positivity of sums, Hadamard products and Hadamard powers: Results
  and counterexamples

abstract:
  We show that, for Hankel matrices, total nonnegativity (resp. total
positivity) of order r is preserved by sum, Hadamard product, and Hadamard
power with real exponent t \ge r-2. We give examples to show that our results
are sharp relative to matrix size and structure (general, symmetric or Hankel).
Some of these examples also resolve the Hadamard critical-exponent problem for
totally positive and totally nonnegative matrices.


title:
Field extension of real values of physical observables in classical
  theory can help attain quantum results

abstract:
  Physical quantities are assumed to take real values, which stems from the
fact that an usual measuring instrument that measures a physical observable
always yields a real number. Here we consider the question of what will happen
if physical observables are allowed to take complex values. In this paper, we
show that by allowing observables in the Bell inequality to take complex
values, a classical physical theory can actually get the same upper bound of
the Bell expression as quantum theory. Also, by extending the real field to the
quaternionic field, we can puzzle out the GHZ problem using local hidden
variable model. Furthermore, we try to build a new type of hidden-variable
theory of a single qubit based on the result.


title:
The effect of magnetization and electric polarization on the anomalous
  transport coefficients of a chiral fluid

abstract:
  The effects of finite magnetization and electric polarization on dissipative
and non-dissipative (anomalous) transport coefficients of a chiral fluid are
studied. First, using the second law of thermodynamics as well as Onsager's
time reversal symmetry principle, the complete set of dissipative transport
coefficients of this medium is derived. It is shown that the properties of the
resulting shear and bulk viscosities are mainly affected by the anisotropy
induced by external electric and magnetic fields. Then, using the fact that the
anomaly induced currents do not contribute to entropy production, the
corresponding algebro-differential equations to non-dissipative anomalous
transport coefficients are derived in a certain derivative expansion. The
solutions of these equations show that, within this approximation, anomalous
transport coefficients are, in particular, given in terms of the electric
susceptibility of the medium.


title:
On Counting Subring-Subcodes of Free Linear Codes Over Finite Principal
  Ideal Rings

abstract:
  Let $R$ be a finite principal ideal ring and $S$ the Galois extension of $R$
of degree $m$. For $k$ and $k_0$, positive integers we determine the number of
free $S$-linear codes $B$ of length $l$ with the property $k = rank_S(B)$ and
$k_0 = rank_R (B\cap R^l)$. This corrects a wrong result which was given in the
case of finite fields.


title:
Investigation of Stimulated Brillouin Scattering in Laser-Plasma
  Interactions

abstract:
  In this paper, we present our numerical simulation results on the Stimulated
Brillouin Scattering (SBS) with injection of an ordinary mode (O-mode)
electromagnetic wave (our pump wave) with frequencies 70 GHz and 110 GHz.
Solving the Fourier transformed Vlasov equation in the velocity space, creates
a profile for distribution function. Time evolution of the distribution
function is investigated as well. Considering an average density for plasma
fusion (n_{0} ~ 10^{19} m^{-3}), we gain a profile for density. Then
two-dimensional instability rate for SBS is obtained. So, the fluctuation of
distribution function affects density and again density affects instability
rate. Increasing the incident light wave frequency causes the instability
growth rate to decrease. Time evolution shows a clear damping for instability
rate since the pump wave's energy is absorbed in plasma (plasma heating).
Furthermore, changing Landau damping for ion acoustic waves (IAW) by changing
ion-to-electron temperature ratio is presented as well, because this damping is
more dominant in high temperatures.


title:
Close binary central stars and the abundance discrepancy - new extreme
  objects

abstract:
  Recent work (Corradi et al. 2015, Jones et al. 2016) has shown that the
phenomenon of extreme abundance discrepancies, where recombination line
abundances exceed collisionally excited line abundances by factors of 10 or
more, seem to be strongly associated with planetary nebulae with close binary
central stars. To further investigate, we have obtained spectra of a sample of
nebulae with known close binary central stars, using FORS2 on the VLT, and we
have discovered several new extreme abundance discrepancy objects. We did not
find any non-extreme discrepancies, suggesting that a very high fraction of
nebulae with close binary central stars also have an extreme abundance
discrepancy.


title:
Almost cyclic elements in Weil representations of finite classical
  groups

abstract:
  This paper is a significant part of a general project aimed to classify all
irreducible representations of finite quasi-simple groups over an algebraically
closed field, in which the image of at least one element is represented by an
almost cyclic matrix. (A square matrix $M$ is called almost cyclic if it is
similar to a block-diagonal matrix with two blocks, such that one block is
scalar and another block is a matrix whose minimum and characteristic
polynomials coincide. Reflections and transvections are examples of almost
cyclic matrices.
  The paper focuses on the Weil representations of finite classical groups, as
there is strong evidence that these representations play a key role in the
general picture.


title: Space anisotropy search at colliders

abstract:
  In the framework of model with Lorentz violation (LV) we discuss a physical
observables for $q\bar{q}$ pair production at lepton-lepton colliders and
describe the experimental signal to be detected. We obtain a conservative
limits on Lorentz-violating dimensionless coupling for quark sector from LEP
data. We also make a phenomenological prediction for LV model at the future
lepton collider.


title:
Embedded Line Scan Image Sensors: The Low Cost Alternative for High
  Speed Imaging

abstract:
  In this paper we propose a low-cost high-speed imaging line scan system. We
replace an expensive industrial line scan camera and illumination with a
custom-built set-up of cheap off-the-shelf components, yielding a measurement
system with comparative quality while costing about 20 times less. We use a
low-cost linear (1D) image sensor, cheap optics including a LED-based or
LASER-based lighting and an embedded platform to process the images. A
step-by-step method to design such a custom high speed imaging system and
select proper components is proposed. Simulations allowing to predict the final
image quality to be obtained by the set-up has been developed. Finally, we
applied our method in a lab, closely representing the real-life cases. Our
results shows that our simulations are very accurate and that our low-cost line
scan set-up acquired image quality compared to the high-end commercial vision
system, for a fraction of the price.


title: Process Monitoring of Extrusion Based 3D Printing via Laser Scanning

abstract:
  Extrusion based 3D Printing (E3DP) is an Additive Manufacturing (AM)
technique that extrudes thermoplastic polymer in order to build up components
using a layerwise approach. Hereby, AM typically requires long production times
in comparison to mass production processes such as Injection Molding. Failures
during the AM process are often only noticed after build completion and
frequently lead to part rejection because of dimensional inaccuracy or lack of
mechanical performance, resulting in an important loss of time and material. A
solution to improve the accuracy and robustness of a manufacturing technology
is the integration of sensors to monitor and control process state-variables
online. In this way, errors can be rapidly detected and possibly compensated at
an early stage. To achieve this, we integrated a modular 2D laser triangulation
scanner into an E3DP machine and analyzed feedback signals. A 2D laser
triangulation scanner was selected here owing to the very compact size,
achievable accuracy and the possibility of capturing geometrical 3D data. Thus,
our implemented system is able to provide both quantitative and qualitative
information. Also, in this work, first steps towards the development of a
quality control loop for E3DP processes are presented and opportunities are
discussed.


title:
Criteria of univalence and fully \alpha--accessibility for p--harmonic
  and p--analytic functions

abstract:
  In this article, we present univalence criteria for polyharmonic and
polyanalytic functions. Our approach yields new a criterion for a polyharmonic
functions to be fully $\alpha$--accessible. Several examples are presented to
illustrate the use of these criteria.


title:
The Continuous Time Random Walk, still trendy: Fifty-year history, state
  of art, and outlook

abstract:
  In this issue we demonstrate the very inspiring role of the continuous-time
random walk (CTRW) formalism and its numerous modifications thanks to their
flexibility and various applications as well its promising perspectives in
different fields of knowledge. A short review of significant achievements and
possibilities is given, however, still far from completeness.


title: A Communication-Efficient Parallel Method for Group-Lasso

abstract:
  Group-Lasso (gLasso) identifies important explanatory factors in predicting
the response variable by considering the grouping structure over input
variables. However, most existing algorithms for gLasso are not scalable to
deal with large-scale datasets, which are becoming a norm in many applications.
In this paper, we present a divide-and-conquer based parallel algorithm
(DC-gLasso) to scale up gLasso in the tasks of regression with grouping
structures. DC-gLasso only needs two iterations to collect and aggregate the
local estimates on subsets of the data, and is provably correct to recover the
true model under certain conditions. We further extend it to deal with
overlappings between groups. Empirical results on a wide range of synthetic and
real-world datasets show that DC-gLasso can significantly improve the time
efficiency without sacrificing regression accuracy.


title:
Exploring the potential of combining time of flight and thermal infrared
  cameras for person detection

abstract:
  Combining new, low-cost thermal infrared and time-of-flight range sensors
provides new opportunities. In this position paper we explore the possibilities
of combining these sensors and using their fused data for person detection. The
proposed calibration approach for this sensor combination differs from the
traditional stereo camera calibration in two fundamental ways. A first
distinction is that the spectral sensitivity of the two sensors differs
significantly. In fact, there is no sensitivity range overlap at all. A second
distinction is that their resolution is typically very low, which requires
special attention. We assume a situation in which the sensors' relative
position is known, but their orientation is unknown. In addition, some of the
typical measurement errors are discussed, and methods to compensate for them
are proposed. We discuss how the fused data could allow increased accuracy and
robustness without the need for complex algorithms requiring large amounts of
computational power and training data.


title:
Systematic variations of macrospicule properties observed by SDO/AIA
  over half a decade

abstract:
  Macrospicules (MS) are localised small-scale jet-like phenomena in the solar
atmosphere, which have the potential to transport considerable amount of
momentum and energy from the lower solar atmospheric regions to the Transition
Region and the low corona. A detailed statistical analysis of their temporal
behaviour and spatial properties is carried out in this work. By means of
state-of-the-art spatial and temporal resolution observations, yielded by the
Atmospheric Imaging Assembly (AIA) of Solar Dynamics Observatory (SDO), we
constructed a database covering a 5.5-year long period, containing 301
macrospicules that occurred between June 2010 and December 2015 detected at
30.4 nm wavelength. Here, we report the long-term variation of the height,
length, average speed and width of MS in Coronal Holes and Quiet Sun areas both
in the northern and southern hemisphere of the Sun. This new database helps to
refine our knowledge about the physical properties of MS. Cross-correlation of
these properties show a relatively strong correlation, but not always a
dominant one. However, a more detailed analysis indicates a wave-like signature
in the behaviour of MS properties in time. The period of these long-term
oscillatory behaviours are just under two years. Also, in terms of solar
north/south hemispheres, a strong asymmetry was found in the spatial
distribution of MS properties, which may be accounted for the solar dynamo.
This latter feature may then indicate a strong and rather intrinsic link
between global internal and local atmospheric phenomena in the Sun.


title:
Sub-GeV-scale signatures of hidden braneworlds up to the Planck scale in
  a $SO(3,1)$-broken bulk

abstract:
  Many-brane universes are at the heart of several cosmological scenarios
related to physics beyond the Standard Model. It is then a major concern to
constrain these approaches. Two-brane Universes involving $SO(3,1)$-broken 5D
bulks are among the cosmological models of interest. They also allow
considering matter exchange between branes, a possible way to test these
scenarios. Neutron disappearance (reappearance) toward (from) the hidden brane
is currently tested with high-precision experiments to constrain the coupling
constant $g$ between the visible and hidden neutron sectors. When dealing with
the sub-GeV-scale quantum dynamics of fermions, any pair of braneworlds can be
described by a non-commutative two-sheeted space-time $M_4\times Z_2$ from
which $g$ emerges. Nevertheless, the calculation of the formal link between $g$
for a neutron and $SO(3,1)$-broken 5D bulks remains an open problem until now
although necessary to constrain these braneworld scenarios. Thanks to a
phenomenological model, we derive $g$ - for a neutron - between the two
braneworlds endowed with their own copy of the standard model in a
$SO(3,1)$-broken 5D bulk. Constraints on interbrane distance and brane energy
scale (or brane thickness) are discussed. While brane energy scale below the
GUT scale is excluded, energy scale up to the Planck limit allows neutron
swapping detection in forthcoming experiments.


title: Unknotted gropes, Whitney towers, and doubly slicing knots

abstract:
  We study the structure of the exteriors of gropes and Whitney towers in
dimension 4, focusing on their fundamental groups. In particular we introduce a
notion of unknottedness of gropes and Whitney towers in the 4-sphere. We prove
that various modifications of gropes and Whitney towers preserve the
unknottedness and do not enlarge the fundamental group. We exhibit handlebody
structures of the exteriors of gropes and Whitney towers constructed by earlier
methods of Cochran, Teichner, Horn, and the first author, and use them to
construct examples of unknotted gropes and Whitney towers. As an application,
we introduce geometric bi-filtrations of knots which approximate the double
sliceness in terms of unknotted gropes and Whitney towers. We prove that the
bi-filtrations do not stabilize at any stage.


title:
On left-invariant Einstein Riemannian metrics that are not geodesic
  orbit

abstract:
  In this paper we prove that the compact Lie group $G_2$ admits a
left-invariant Einstein metric that is not geodesic orbit. In order to prove
the required assertion, we develop some special tools for geodesic orbit
Riemannian manifolds. It should be noted that a suitable metric is discovered
in a recent paper by I. Chrysikos and Y. Sakane, where the authors proved also
that this metric is not naturally reductive.


title:
Operation of Multi-Pixel Radio-Frequency Superconducting Nanowire
  Single-Photon Detector Arrays

abstract:
  The concept of the radio-frequency superconducting nanowire single-photon
detector (RF-SNSPD) allows frequency-division multiplexing (FDM) of the bias
and readout lines of several SNSPDs. Using this method, a multi-pixel array can
be operated by only one feed line. Consequently, the system complexity as well
as the heat load is significantly reduced. To allocate many pixels into a small
bandwidth the quality factor of each device is crucial. In this paper, we
present an improved RF-SNSPD design. This new design enables a simple tuning of
the quality factor as well as the resonant frequency. With a two-pixel device
we have demonstrated the operation without crosstalk between the detectors and
showed the time, spatial and photon number resolution. Thereby a single pixel
requires only a bandwidth of 14 MHz.


title: Preferential attachment combined with random number of choices

abstract:
  We study an asymptotical behavior of the maximal degree in the degree
distribution in an evolving tree model combining the local choice and the
Mori's preferential attachment. In the considered model, the random graph is
constructed in the following way. At each step, a new vertex is introduced.
Then, we connect it with one (the vertex with the largest degree is chosen) of
$d$ (for random $d$) possible neighbors, which are sampled from the set of the
existing vertices with the probability proportional to their degrees plus some
parameter $\beta>-1$. It is known that the maximum of the degree distribution
for non-random $d>2$ has linear behaviour and, for $d=2$, asymptoticaly equals
to $n/\ln n$ up to a constant factor. We prove that if $\mathbb{E}d<2+\beta$,
the maximal degree has sublinear behavior with the power
$\mathbb{E}d/(2+\beta)$ (as in the preferential attachment without choice), if
$\mathbb{E}d>2+\beta$, it has linear behavior and if $\mathbb{E}d=2+\beta$ the
maximal degree is of order $n/\ln n$. The proof combines standard preferential
attachment approaches with martingales and stochastic approximation techniques.
We also use stochastic approximation results to get a multidimentional central
limit theorem for the numbers of vertices with fixed degrees.


title: The Schr{\"o}dinger equation with spatial white noise potential

abstract:
  We consider the linear and nonlinear Schr{\"o}dinger equation with a spatial
white noise as a potential in dimension 2. We prove existence and uniqueness of
solutions thanks to a change of unknown originally used in [8] and conserved
quantities.


title:
The temporal evolution of exposed water ice-rich areas on the surface of
  67P/Churyumov-Gerasimenko: spectral analysis

abstract:
  Water ice-rich patches have been detected on the surface of comet
67P/Churyumov-Gerasimenko by the VIRTIS hyperspectral imager on-board the
Rosetta spacecraft, since the orbital insertion in late August 2014. Among
those, three icy patches have been selected, and VIRTIS data are used to
analyse their properties and their temporal evolution while the comet was
moving towards the Sun. We performed an extensive analysis of the spectral
parameters, and we applied the Hapke radiative transfer model to retrieve the
abundance and grain size of water ice, as well as the mixing modalities of
water ice and dark terrains on the three selected water ice rich areas. Study
of the spatial distribution of the spectral parameters within the ice-rich
patches has revealed that water ice follows different patterns associated to a
bimodal distribution of the grains: ~50 {\mu}m sized and ~2000 {\mu}m sized. In
all three cases, after the first detections at about 3.5 AU heliocentric
distance, the spatial extension and intensity of the water ice spectral
features increased, it reached a maximum after 60-100 days at about 3.0 AU, and
was followed by an approximately equally timed decrease and disappearanceat
about ~2.2 AU, before perihelion. The behaviour of the analysed patches can be
assimilated to a seasonal cycle. In addition we found evidence of short-term
variability associated to a diurnal water cycle. The similar lifecycle of the
three icy regions indicates that water ice is uniformly distributed in the
subsurface layers, and no large water ice reservoirs are present.


title: Halpha Doppler shifts in a tornado in the solar corona

abstract:
  High resolution movies in 193 A from the Atmospheric Imaging Assembly (AIA)
on the Solar Dynamic Observatory SDO show apparent rotation in the leg of a
prominence observed during a coordinated campaign. Such structures are commonly
referred to as tornadoes. Time-distance intensity diagrams of the AIA data show
the existence of oscillations suggesting that the structure is rotating.
  The aim of this paper is to understand if the cool plasma at chromospheric
temperatures inside the tornado is rotating around its central axis. The
tornado was also observed in Halpha with a cadence of 30 seconds by the MSDP
spectrograph, operating at the Solar Tower in Meudon. The MSDP provides
sequences of simultaneous spectra in a 2D field of view from which a cube of
Doppler velocity maps is retrieved.
  The Halpha Doppler maps show a pattern with alternatively blueshifted and
redshifted areas of 5 to 10 arcsec wide. Over time the blueshifted areas become
redshifted and vice versa, with a quasi-periodicity of 40 to 60 minutes. Weaker
amplitude oscillations with periods of 4 to 6 minutes are superimposed onto
these large period oscillations.
  The Doppler pattern observed in Halpha cannot be interpreted as rotation of
the cool plasma inside the tornado. The H$\alpha$ velocity observations give
strong constraints on the possible interpretations of the AIA tornado


title:
A simple and efficient SNN and its performance & robustness evaluation
  method to enable hardware implementation

abstract:
  Spiking Neural Networks (SNN) are more closely related to brain-like
computation and inspire hardware implementation. This is enabled by small
networks that give high performance on standard classification problems. In
literature, typical SNNs are deep and complex in terms of network structure,
weight update rules and learning algorithms. This makes it difficult to
translate them into hardware. In this paper, we first develop a simple
2-layered network in software which compares with the state of the art on four
different standard data-sets within SNNs and has improved efficiency. For
example, it uses lower number of neurons (3 x), synapses (3.5 x) and epochs for
training (30 x) for the Fisher Iris classification problem. The efficient
network is based on effective population coding and synapse-neuron co-design.
Second, we develop a computationally efficient (15000 x) and accurate
(correlation of 0.98) method to evaluate the performance of the network without
standard recognition tests. Third, we show that the method produces a
robustness metric that can be used to evaluate noise tolerance.


title: Invertibility of graphs with a unique perfect matching

abstract:
  In this paper we investigate invertibility of graphs with a unique perfect
matching, i.e. graphs having a unique 1-factor. We recall the new notion of the
so-called negatively invertible graphs investigated by the authors in the
recent paper. It is an extension of the classical definition of an inverse
graph due to Godsil. We characterize all graphs with a unique perfect matching
on $m\le 6$ vertices with respect to their positive and negative invertibility.
We show that negatively invertible graphs exhibit properties like
selfinvertibility which cannot be observed within the class of positively
invertible non-bipartite graphs with a unique perfect matching.


title:
Intrinsic Ferromagnetism in the Diluted Magnetic Semiconductor
  Co:TiO$_2$

abstract:
  Here we present a study of magnetism in \CTO\ anatase films grown by pulsed
laser deposition under a variety of oxygen partial pressures and deposition
rates. Energy-dispersive spectrometry and transition electron microscopy
analyses indicate that a high deposition rate leads to a homogeneous
microstructure, while very low rate or postannealing results in cobalt
clustering. Depth resolved low-energy muon spin rotation experiments show that
films grown at a low oxygen partial pressure ($\approx 10^{-6}$ torr) with a
uniform structure are fully magnetic, indicating intrinsic ferromagnetism.
First principles calculations identify the beneficial role of low oxygen
partial pressure in the realization of uniform carrier-mediated ferromagnetism.
This work demonstrates that Co:TiO$_2$ is an intrinsic diluted magnetic
semiconductor.


title:
Light propagation in the gravitational field of one arbitrarily moving
  pointlike body in the 2PN approximation

abstract:
  An analytical solution for the light trajectory in the near-zone of the
gravitational field of one pointlike body in arbitrary slow-motion in the
post-post-Newtonian approximation is presented in harmonic gauge. Expressions
for total light deflection and time delay are given. The presented solution is
a further step toward high-precision astrometry aiming at nano-arcsecond level
of accuracy.


title:
TEE, a simple estimator for the precision of eclipse and transit minimum
  times

abstract:
  Context: Transit or eclipse timing variations have proven to be a valuable
tool in exoplanet research. However, no simple way to estimate the potential
precision of such timing measures has been presented yet, nor are guidelines
available regarding the relation between timing errors and sampling rate.
  Aims: A `timing error estimator' (TEE) equation is presented that requires
only basic transit parameters as input. With the TEE, it is straightforward to
estimate timing precisions both for actual data as well as for future
instruments, such as the TESS and PLATO space missions.
  Methods: A derivation of the timing error based on a trapezoidal transit
shape is given. We also verify the TEE on realistically modeled transits using
Monte Carlo simulations and determine its validity range, exploring in
particular the interplay between ingress/egress times and sampling rates.
  Results: The simulations show that the TEE gives timing errors very close to
the correct value, as long as the temporal sampling is faster than transit
ingress/egress durations and transits with very low S/N are avoided.
  Conclusions: The TEE is a useful tool to estimate eclipse or transit timing
errors in actual and future data-sets. In combination with an equation to
estimate period errors (Deeg 2015), predictions for the ephemeris precision of
long-coverage observations are possible as well. The tests for the TEE's
validity-range led also to implications for instrumental design: Temporal
sampling has to be faster than transit in- or egress durations, or a loss in
timing-precision will occur. An application to the TESS mission shows that
transits close to its detection limit will have timing uncertainties that
exceed 1 hour within a few months after their acquisition. Prompt follow-up
observations will be needed to avoid a `loosing' of their ephemeris.


title:
Phase diagram of Eu magnetic ordering in Sn-flux-grown
  Eu(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ single crystals

abstract:
  The magnetic ground state of the Eu$^{2+}$ moments in a series of
Eu(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ single crystals grown from the Sn flux has
been investigated in detail by neutron diffraction measurements. Combined with
the results from the macroscopic properties (resistivity, magnetic
susceptibility and specific heat) measurements, a phase diagram describing how
the Eu magnetic order evolves with Co doping in
Eu(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ is established. The ground-state magnetic
structure of the Eu$^{2+}$ spins is found to develop from the A-type
antiferromagnetic (AFM) order in the parent compound, via the A-type canted AFM
structure with some net ferromagnetic (FM) moment component along the
crystallographic $\mathit{c}$ direction at intermediate Co doping levels,
finally to the pure FM order at relatively high Co doping levels. The ordering
temperature of Eu declines linearly at first, reaches the minimum value of
16.5(2) K around $\mathit{x}$ = 0.100(4), and then reverses upwards with
further Co doping. The doping-induced modification of the indirect
Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between the Eu$^{2+}$ moments,
which is mediated by the conduction $\mathit{d}$ electrons on the (Fe,Co)As
layers, as well as the change of the strength of the direct interaction between
the Eu$^{2+}$ and Fe$^{2+}$ moments, might be responsible for the change of the
magnetic ground state and the ordering temperature of the Eu sublattice. In
addition, for Eu(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ single crystals with 0.10
$\leqslant$ $\mathit{x}$ $\leqslant$ 0.18, strong ferromagnetism from the Eu
sublattice is well developed in the superconducting state, where a spontaneous
vortex state is expected to account for the compromise between the two
competing phenomena.


title:
Unconventional superconductivity induced in Nb films by adsorbed chiral
  molecules

abstract:
  Motivated by recent observations of chiral-induced magnetization and
spin-selective transport we studied the effect of chiral molecules on
conventional BCS superconductors. By applying scanning tunneling spectroscopy,
we demonstrate that the singlet-pairing s-wave order parameter of Nb is
significantly altered upon adsorption of chiral polyalanine alpha-helix
molecules on its surface. The tunneling spectra exhibit zero-bias conductance
peaks embedded inside gaps or gap-like features, suggesting the emergence of
unconventional triplet-pairing components with either d-wave or p-wave
symmetry, as corroborated by simulations. These results may open a way for
realizing simple superconducting spintroinics devices.


title: Creation of Elko particles in asymptotically expanding universe

abstract:
  In the present article we study the process of particle creation for Elko
spinor fields as a consequence of expansion of the universe. We study the
effect driven by a expanding background that is asymptotically minkowskian in
the past and future. The differential equation that governs the time mode
function is obtained for the conformal coupling case and, although its solution
is non-analytic, within an approximation that preserves the characteristics of
the terms that break the analyticity, analytic solutions are obtained. Thus, by
means of the Bogolyubov transformations technique, the number density of
particles created is obtained, which can be compared to exact solutions already
present in literature for scalar and Dirac particles. The spectrum of created
particles is obtained and it was found that it is a generalization of the
scalar field case, which converges to the scalar field one when the specific
terms concerning the Elko field are dropped out. We also found that lighter
Elko particles are created in larger quantities than Dirac fermionic particles.
By considering the Elko particles as candidate to dark matter in the universe,
such result shows that there are more light dark matter (Elko) particles
created by gravitational effects in the universe than baryonic (fermionic)
matter, in agreement to standard model.


title: Derived categories of curves as components of Fano manifolds

abstract:
  We prove that the derived category $D(C)$ of a generic curve of genus greater
than one embeds into the derived category $D(M)$ of the moduli space $M$ of
rank two stable bundles on $C$ with fixed determinant of odd degree.


title:
The Galah Survey: Classification and diagnostics with t-SNE reduction of
  spectral information

abstract:
  Galah is an ongoing high-resolution spectroscopic survey with the goal of
disentangling the formation history of the Milky Way, using the fossil remnants
of disrupted star formation sites which are now dispersed around the Galaxy. It
is targeting a randomly selected, magnitude limited ($V \leq 14$) sample of
stars, with the goal of observing one million objects. To date, 300,000 spectra
have been obtained. Not all of them are correctly processed by parameter
estimation pipelines and we need to know about them. We present a
semi-automated classification scheme which identifies different types of
peculiar spectral morphologies, in an effort to discover and flag potentially
problematic spectra and thus help to preserve the integrity of the survey's
results. To this end we employ a recently developed dimensionality reduction
technique t-SNE (t-distributed Stochastic Neighbour Embedding), which enables
us to represent the complex spectral morphology in a two-dimensional projection
map while still preserving the properties of the local neighbourhoods of
spectra. We find that the majority (178,483) of the 209,533 Galah spectra
considered in this study represents normal single stars, whereas 31,050
peculiar and problematic spectra with very diverse spectral features pertaining
to 28,579 stars are distributed into 10 classification categories: Hot stars,
Cool metal-poor giants, Molecular absorption bands, Binary stars,
H$\alpha$/H$\beta$ emission, H$\alpha$/H$\beta$ emission superimposed on
absorption, H$\alpha$/H$\beta$ P-Cygni, H$\alpha$/H$\beta$ inverted P-Cygni,
Lithium absorption, and Problematic. Classified spectra with supplementary
information are presented in the catalogue, indicating candidates for follow-up
observations and population studies of the short-lived phases of stellar
evolution.


title:
How structure sculpts function: unveiling the contribution of anatomical
  connectivity to the brain's spontaneous correlation structure

abstract:
  Intrinsic brain activity is characterized by highly structured co-activations
between different regions, whose origin is still under debate. In this paper,
we address the question whether it is possible to unveil how the underlying
anatomical connectivity shape the brain's spontaneous correlation structure. We
start from the assumption that in order for two nodes to exhibit large
covariation, they must be exposed to similar input patterns from the entire
network. We then acknowledge that information rarely spreads only along an
unique route, but rather travels along all possible paths. In real networks the
strength of local perturbations tends to decay as they propagate away from the
sources, leading to a progressive attenuation of the original information
content and, thus, of their influence. We use these notions to derive a novel
analytical measure, $\mathcal{T}$ , which quantifies the similarity of the
whole-network input patterns arriving at any two nodes only due to the
underlying topology, in what is a generalization of the matching index. We show
that this measure of topological similarity can indeed be used to predict the
contribution of network topology to the expected correlation structure, thus
unveiling the mechanism behind the tight but elusive relationship between
structure and function in complex networks. Finally, we use this measure to
investigate brain connectivity, showing that information about the topology
defined by the complex fabric of brain axonal pathways specifies to a large
extent the time-average functional connectivity observed at rest.