title:
Topological energy gaps in the [111]-oriented InAs/GaSb and GaSb/InAs
  core-shell nanowires

abstract:
  The [111]-oriented InAs/GaSb and GaSb/InAs core-shell nanowires have been
studied by the $8\times 8$ Luttinger-Kohn $\vec{k}\cdot\vec{p}$ Hamiltonian to
search for non-vanishing fundamental gaps between inverted electron and hole
bands. We focus on the variations of the topologically nontrivial fundamental
gap, the hybridization gap, and the effective gap with the core radius and
shell thickness of the nanowires. The evolutions of all the energy gaps with
the structural parameters are shown to be dominantly governed by quantum size
effects. With a fixed core radius, a topologically nontrivial fundamental gap
exists only at intermediate shell thicknesses. The maximum gap is $\sim 4.4$
meV for GaSb/InAs and $\sim 3.5$ meV for InAs/GaSb core-shell nanowires, and
for the GaSb/InAs core-shell nanowires the gap persists over a wider range of
geometrical parameters. The intrinsic reason for these differences between the
two types of nanowires is that in the shell the electron-like states of InAs is
more delocalized than the hole-like state of GaSb, while in the core the
hole-like state of GaSb is more delocalized than the electron-like state of
InAs, and both features favor stronger electron-hole hybridization. Since
similar features of the electron- and hole-like states have been found in
nanowires of other materials, it could serve as a common rule to put the
hole-like state in the core while the electron-like state in the shell of a
core-shell nanowire to achieve better topological properties.


title: Superconductivity in topologically nontrivial material Au2Pb

abstract:
  The search for nontrivial superconductivity in novel quantum materials is
currently a most attractive topic in condensed matter physics and material
science. The experimental studies have progressed quickly over the past couple
of years. In this article, we report systematic studies of superconductivity in
Au2Pb single crystals. The bulk superconductivity (onset transition
temperature, Tconset= 1.3 K) of Au2Pb is characterized by both transport and
diamagnetic measurements, where the upper critical field Hc2 shows unusual
quasi-linear temperature dependence. The superconducting gap is revealed by
point contact measurement with gold tip. However, when using tungsten (W) tip,
which is much harder, the superconducting gap probed is largely enhanced as
demonstrated by the increases of both Tconset and upper critical field (Hc2).
This can be interpreted as a result of increase in density of states under
external anisotropic stress imposed by the tip, as revealed by first-principles
calculations. Furthermore, novel phase winding of the pseudospin texture along
k-space loops around the Fermi energy is uncovered from the calculations,
indicating that the observed superconductivity in Au2Pb may have nontrivial
topology.


title:
Analysis of the Packet Loss Probability in Energy Harvesting Cognitive
  Radio Networks

abstract:
  A Markovian battery model is proposed to provide the variation of energy
states for energy harvesting (EH) secondary users (SUs) in the EH cognitive
radio networks (CRN). Based on the proposed battery model, we derive the packet
loss probability in the EH SUs due to sensing inaccuracy and energy outage.
With the proposed analysis, the packet loss probability can easily be predicted
and utilized to optimize the transmission policy (i.e., opportunities for
successful transmission and EH) of EH SUs to improve their throughput.
Especially, the proposed method can be applied to upper layer (scheduling and
routing) optimization. To this end, we validate the proposed analysis through
Monte-Carlo simulation and show an agreement between the analysis and
simulations results.


title: Propri\'et\'es combinatoires du bord d'un groupe hyperbolique

abstract:
  The goal of this survey is to present combinatorial modulus that have been
recently used to study quasi-conformal properties of boundaries of hyperbolic
groups. First, we will recall well known rigidity results and questions that
motivated the introduction of these tools. Then we will define combinatorial
modulus and the combinatorial Loewner property that provide new approaches to
rigidity questions. Finally, we will describe some applications of these tools
through recent results.
  -----
  Le but de ce survol est de pr\'esenter les modules combinatoires r\'ecemment
utilis\'es pour \'etudier les propri\'et\'es quasi-conformes des bords des
groupes hyperboliques. Dans un premier temps, on rappellera quelques
r\'esultats et questions de rigidit\'e bien connus qui ont motiv\'es
l'introduction de ces outils. Puis on d\'efinira les modules combinatoires et
la propri\'et\'e de L\"owner combinatoire qui offrent une nouvelle approche
pour r\'esoudre des probl\`emes ouverts depuis longtemps. Enfin, on d\'ecrira
des applications concr\`etes de ces outils \`a travers quelques r\'esultats
r\'ecents.


title:
Residual-based a Posteriori Error Estimate for Interface Problems:
  Nonconforming Linear Elements

abstract:
  In this paper, we study a modified residual-based a posteriori error
estimator for the nonconforming linear finite element approximation to the
interface problem. The reliability of the estimator is analyzed by a new and
direct approach without using the Helmholtz decomposition. It is proved that
the estimator is reliable with constant independent of the jump of diffusion
coefficients across the interfaces, without the assumption that the diffusion
coefficient is quasi-monotone. Numerical results for one test problem with
intersecting interfaces are also presented.


title: Convolutional Neural Networks using Logarithmic Data Representation

abstract:
  Recent advances in convolutional neural networks have considered model
complexity and hardware efficiency to enable deployment onto embedded systems
and mobile devices. For example, it is now well-known that the arithmetic
operations of deep networks can be encoded down to 8-bit fixed-point without
significant deterioration in performance. However, further reduction in
precision down to as low as 3-bit fixed-point results in significant losses in
performance. In this paper we propose a new data representation that enables
state-of-the-art networks to be encoded to 3 bits with negligible loss in
classification performance. To perform this, we take advantage of the fact that
the weights and activations in a trained network naturally have non-uniform
distributions. Using non-uniform, base-2 logarithmic representation to encode
weights, communicate activations, and perform dot-products enables networks to
1) achieve higher classification accuracies than fixed-point at the same
resolution and 2) eliminate bulky digital multipliers. Finally, we propose an
end-to-end training procedure that uses log representation at 5-bits, which
achieves higher final test accuracy than linear at 5-bits.


title:
Uniform K-stability and asymptotics of energy functionals in K\"ahler
  geometry

abstract:
  Consider a polarized complex manifold (X,L) and a ray of positive metrics on
L defined by a positive metric on a test configuration for (X,L). For most of
the common functionals in K\"ahler geometry, we prove that the slope at
infinity along the ray is given by evaluating the non-Archimedean version of
the functional (as defined in our earlier paper) at the non-Archimedean metric
on L defined by the test configuration. Using this asymptotic result, we show
that coercivity of the Mabuchi functional implies uniform K-stability.


title: A stochastic model for speciation by mating preferences

abstract:
  Mechanisms leading to speciation are a major focus in evolutionary biology.
In this paper, we present and study a stochastic model of population where
individuals, with type a or A, are equivalent from ecological, demographical
and spatial points of view, and differ only by their mating preference: two
individuals with the same genotype have a higher probability to mate and
produce a viable offspring. The population is subdivided in several patches and
individuals may migrate between them. We show that mating preferences by
themselves, even if they are very small, are enough to entail reproductive
isolation between patches, and we provide the time needed for this isolation to
occur as a function of the population size. Our results rely on a fine study of
the stochastic process and of its deterministic limit in large population,
which is given by a system of coupled nonlinear differential equations.
Besides, we propose several generalisations of our model, and prove that our
findings are robust for those generalisations.


title:
Medium-induced gluon radiation in hard forward parton scattering in the
  saturation formalism

abstract:
  We derive the medium-induced, coherent gluon radiation spectrum associated
with the hard forward scattering of an energetic parton off a nucleus, in the
saturation formalism and within the Gaussian approximation for the relevant
correlators of Wilson lines. The calculation reproduces the simple expression
for the spectrum previously obtained in the opacity expansion formalism, and
rigorously specifies its validity range. The connection between the
calculations in the opacity expansion and saturation formalisms is made
apparent. This study may serve as a first step in order to implement
consistently induced coherent energy loss and gluon shadowing in
`saturation-based models' of hadron nuclear suppression in proton-nucleus
collisions.


title: Whitening-Free Least-Squares Non-Gaussian Component Analysis

abstract:
  Non-Gaussian component analysis (NGCA) is an unsupervised linear dimension
reduction method that extracts low-dimensional non-Gaussian "signals" from
high-dimensional data contaminated with Gaussian noise. NGCA can be regarded as
a generalization of projection pursuit (PP) and independent component analysis
(ICA) to multi-dimensional and dependent non-Gaussian components. Indeed,
seminal approaches to NGCA are based on PP and ICA. Recently, a novel NGCA
approach called least-squares NGCA (LSNGCA) has been developed, which gives a
solution analytically through least-squares estimation of log-density gradients
and eigendecomposition. However, since pre-whitening of data is involved in
LSNGCA, it performs unreliably when the data covariance matrix is
ill-conditioned, which is often the case in high-dimensional data analysis. In
this paper, we propose a whitening-free LSNGCA method and experimentally
demonstrate its superiority.


title:
Oscillation of a Class of Impulsive Differential Equations with
  Continuous and Piecewise Constant Arguments

abstract:
  A class of first order linear impulsive differential equation with continuous
and piecewise constant arguments is studied. Sufficient conditions for the
oscillation of the solutions are obtained.


title: Unconventional electron states in $\delta$-doped SmTiO$_3$

abstract:
  The Mott-insulating distorted perovskite SmTiO$_3$, doped with a single SrO
layer in a quantum-well architecture is studied by the combination of density
functional theory with dynamical mean-field theory. A rich correlated
electronic structure in line with recent experimental investigations is
revealed by the given realistic many-body approach to a large-unit-cell oxide
heterostructure. Coexistence of conducting and Mott-insulating TiO$_2$ layers
prone to magnetic order gives rise to multi-orbital electronic transport beyond
standard Fermi-liquid theory. First hints towards a pseudogap opening due to
electron-electron scattering within a background of ferromagnetic and
antiferromagnetic fluctuations are detected.


title: Right Ideals of a Ring and Sublanguages of Science

abstract:
  Among Zellig Harris's numerous contributions to linguistics his theory of the
sublanguages of science probably ranks among the most underrated. However, not
only has this theory led to some exhaustive and meaningful applications in the
study of the grammar of immunology language and its changes over time, but it
also illustrates the nature of mathematical relations between chunks or subsets
of a grammar and the language as a whole. This becomes most clear when dealing
with the connection between metalanguage and language, as well as when
reflecting on operators.
  This paper tries to justify the claim that the sublanguages of science stand
in a particular algebraic relation to the rest of the language they are
embedded in, namely, that of right ideals in a ring.


title:
Using Steinberg algebras to study decomposability of Leavitt path
  algebras

abstract:
  Given an arbitrary graph $E$ we investigate the relationship between $E$ and
the groupoid $G_E$.
  We show that there is a lattice isomorphism between the lattice of pairs $(H,
S)$, where $H$ is a hereditary and saturated set of vertices and $S$ is a set
of breaking vertices {associated to $H $}, onto the lattice of open invariant
subsets of $G_E^{(0)}$. We use this lattice isomorphism to characterize the
decomposability of the Leavitt path algebra $L_K(E)$, where $K$ is a field.
  First we find a graph condition to characterise when an open invariant subset
of $G_E^{(0)}$ is closed.
  Then we give both a graph condition and a groupoid condition each of which is
equivalent to $L_K(E)$ being decomposable {in the sense that it can be written
as a direct sum of two nonzero ideals}.


title: Shaping the GeV-spectra of bright blazars

abstract:
  The non-thermal spectra of jetted active galactic nuclei show a variety of
shapes in their low- and high energy components. In some of the brightest
Fermi-LAT blazars, prominent spectral breaks at a few GeV have been regularly
detected, which is inconsistent with conventional cooling effects. We study the
effects of continuous time-dependent injection of electrons into the jet with
differing rates, durations, locations, and power-law spectral indices, and
evaluate its impact on the ambient emitting particle spectrum at a given
snapshot time in the framework of a leptonic blazar emission model. The
emitting electron spectrum is calculated by Compton cooling the continuously
injected electrons, where target photons are assumed to be provided by the
accretion disk and broad line region. We calculate the non-thermal photon
spectra produced by inverse Compton scattering of these external target
radiation fields using the full Compton cross-section in the head-on
approximation. By means of a comprehensive parameter study we present the
resulting ambient electron and photon spectra, and discuss the influence of
each injection parameter. Varying the injection parameters has a notable
influence on the spectral shapes, which can be used to set constraints on the
injection scenarios. We apply our model to the flare state spectral energy
distribution of 3C454.3, and to the FSRQ PKS1510-089. For both sources we show
two different model fits, corresponding to different injection scenarios. In
all four injection scenarios impulsive particle injection is disfavored. Our
model aims towards bridging jet emission with acceleration models using a
phenomenological approach. Blazar spectral data can be analyzed with this model
to constrain injection parameters, in addition to the conventional parameter
values of steady-state emission models, if sufficient broad multifrequency
coverage is provided.


title: Conformal geometry of timelike curves in the (1+2)-Einstein universe

abstract:
  We study the conformal geometry of timelike curves in the (1+2)-Einstein
universe, the conformal compactification of Minkowski 3-space defined as the
quotient of the null cone of $\mathbb{R}^{2,3}$ by the action by positive
scalar multiplications. The purpose is to describe local and global conformal
invariants of timelike curves and to address the question of existence and
properties of closed trajectories for the conformal strain functional. Some
relations between the conformal geometry of timelike curves and the geometry of
knots and links in the 3-sphere are discussed.


title:
Locally covariant quantum field theory and the spin-statistics
  connection

abstract:
  The framework of locally covariant quantum field theory, an axiomatic
approach to quantum field theory in curved spacetime, is reviewed. As a
specific focus, the connection between spin and statistics is examined in this
context. A new approach is given, which allows for a more operational
description of theories with spin and for the derivation of a more general
version of the spin-statistics connection in curved spacetimes than previously
available. This part of the text is based on arXiv:1503.05797 and a forthcoming
publication; the emphasis here is on the fundamental ideas and motivation.


title: Classical impurities and boundary Majorana zero modes in quantum chains

abstract:
  We study the response of classical impurities in quantum Ising chains. The Z2
degeneracy they entail renders the existence of two decoupled Majorana modes at
zero energy an exact property of a finite system at arbitrary values of its
bulk parameters. We trace the evolution of these modes across the transition
from the disordered phase to the ordered one and analyze the concomitant
qualitative changes of local magnetic properties of an isolated impurity. In
the disordered phase, the two ground states differ only close to the impurity,
and they are related by the action of an explicitly constructed quasi-local
operator. In this phase the local transverse spin susceptibility follows a
Curie law. The critical response of a boundary impurity is logarithmically
divergent and maps to the two-channel Kondo problem, while it saturates for
critical bulk impurities, as well as in the ordered phase. The results for the
Ising chain translate to the related problem of a resonant level coupled to a
1d p-wave superconductor or a Peierls chain, whereby the magnetic order is
mapped to topological order. We find that the topological phase always exhibits
a continuous impurity response to local fields as a result of the level
repulsion of local levels from the boundary Majorana zero mode. In contrast,
the disordered phase generically features a discontinuous magnetization or
charging response. This difference constitutes a general thermodynamic
fingerprint of topological order in phases with a bulk gap.


title:
Boundary-Induced Pattern Formation from Temporal Oscillation: Spatial
  Map Analysis

abstract:
  Boundary-induced pattern formation from a spatially uniform state is
investigated using one-dimensional reaction-diffusion equations. The temporal
oscillation is successively transformed into a spatially periodic pattern,
triggered by diffusion from the fixed boundary. We introduced a spatial map,
whose temporal sequence, under selection criteria from multiple stationary
solutions, can completely reproduce the emergent pattern, by replacing the time
with space. The relationship of the pattern wavelength with the period of
oscillation is also obtained. The generality of the pattern selection process
and algorithm is discussed with possible relevance to biological morphogenesis.


title: Fractional Clique Decompositions of Dense Partite Graphs

abstract:
  We give a minimum degree condition sufficent to ensure the existence of a
fractional $K_r$-decomposition in a balanced $r$-partite graph (subject to some
further simple necessary conditions). This generalises the non-partite problem
studied recently by Barber, Lo, K\"uhn, Osthus and the author, and the
$3$-partite fractional $K_3$-decomposition problem studied recently by Dukes.
Combining our result with recent work by Barber, K\"uhn, Lo, Osthus and Taylor,
this gives a minimum degree condition sufficient to ensure the existence of a
(non-fractional) $K_r$-decomposition in a balanced $r$-partite graph (subject
to the same simple necessary conditions).


title: Pluriassociative algebras I: The pluriassociative operad

abstract:
  Diassociative algebras form a categoy of algebras recently introduced by
Loday. A diassociative algebra is a vector space endowed with two associative
binary operations satisfying some very natural relations. Any diassociative
algebra is an algebra over the diassociative operad, and, among its most
notable properties, this operad is the Koszul dual of the dendriform operad. We
introduce here, by adopting the point of view and the tools offered by the
theory of operads, a generalization on a nonnegative integer parameter $\gamma$
of diassociative algebras, called $\gamma$-pluriassociative algebras, so that
$1$-pluriassociative algebras are diassociative algebras. Pluriassociative
algebras are vector spaces endowed with $2\gamma$ associative binary operations
satisfying some relations. We provide a complete study of the
$\gamma$-pluriassociative operads, the underlying operads of the category of
$\gamma$-pluriassociative algebras. We exhibit a realization of these operads,
establish several presentations by generators and relations, compute their
Hilbert series, show that they are Koszul, and construct the free objects in
the corresponding categories. We also study several notions of units in
$\gamma$-pluriassociative algebras and propose a general way to construct such
algebras. This paper ends with the introduction of an analogous generalization
of the triassociative operad of Loday and Ronco.


title:
Estimating Quantile Families of Loss Distributions for Non-Life
  Insurance Modelling via L-moments

abstract:
  This paper discusses different classes of loss models in non-life insurance
settings. It then overviews the class Tukey transform loss models that have not
yet been widely considered in non-life insurance modelling, but offer
opportunities to produce flexible skewness and kurtosis features often required
in loss modelling. In addition, these loss models admit explicit quantile
specifications which make them directly relevant for quantile based risk
measure calculations. We detail various parameterizations and sub-families of
the Tukey transform based models, such as the g-and-h, g-and-k and g-and-j
models, including their properties of relevance to loss modelling.
  One of the challenges with such models is to perform robust estimation for
the loss model parameters that will be amenable to practitioners when fitting
such models. In this paper we develop a novel, efficient and robust estimation
procedure for estimation of model parameters in this family Tukey transform
models, based on L-moments. It is shown to be more robust and efficient than
current state of the art methods of estimation for such families of loss models
and is simple to implement for practical purposes.

categories: q-fin.RM math.ST stat.AP stat.ME stat.TH


title:
Non-radial pulsation in first overtone Cepheids of the Small Magellanic
  Cloud

abstract:
  We analyse photometry for 138 first overtone Cepheids from the Small
Magellanic Cloud, in which Optical Gravitational Lensing Experiment (OGLE) team
discovered additional variability with period shorter than first overtone
period, and period ratios in the (0.60, 0.65) range. In the Petersen diagram
these stars form three well separated sequences. The additional variability
cannot correspond to other radial mode. This form of pulsation is still
puzzling.
  We find that amplitude of the additional variability is small, typically 2-4
per cent of the first overtone amplitude, which corresponds to 2-5 mmag. In
some stars we find simultaneously two close periodicities corresponding to two
sequences in the Petersen diagram. The most important finding is the detection
of power excess at half the frequency of the additional variability (at
subharmonic) in 35 per cent of the analysed stars. Interestingly, power excess
at subharmonic frequency is detected mostly for stars of the middle sequence in
the Petersen diagram (74 per cent), incidence rate is much lower for stars of
the top sequence (31 per cent), and phenomenon is not detected for stars of the
bottom sequence. The amplitude and/or phase of the additional periodicities
strongly vary in time.
  Similar form of pulsation is observed in first overtone RR Lyrae stars. Our
results indicate that the nature and cause of this form of pulsation is the
same in the two groups of classical pulsators; consequently, a common model
explaining this form of pulsation should be searched for. Our results favour
the theory of the excitation of non-radial modes of angular degrees 7, 8 and 9,
proposed recently by Dziembowski.


title:
Clique decompositions of multipartite graphs and completion of Latin
  squares

abstract:
  Our main result essentially reduces the problem of finding an
edge-decomposition of a balanced r-partite graph of large minimum degree into
r-cliques to the problem of finding a fractional r-clique decomposition or an
approximate one. Together with very recent results of Bowditch and Dukes as
well as Montgomery on fractional decompositions into triangles and cliques
respectively, this gives the best known bounds on the minimum degree which
ensures an edge-decomposition of an r-partite graph into r-cliques (subject to
trivially necessary divisibility conditions). The case of triangles translates
into the setting of partially completed Latin squares and more generally the
case of r-cliques translates into the setting of partially completed mutually
orthogonal Latin squares.


title:
Topological Phase Transitions and Thouless Pumping of Light in Photonic
  Waveguide Arrays

abstract:
  Photonic waveguide arrays provide an excellent platform for simulating
conventional topological systems, and they can also be employed for the study
of novel topological phases in photonics systems. However, a direct measurement
of bulk topological invariants remains a great challenge. Here we study
topological features of generalized commensurate Aubry-Andr\'{e}-Harper (AAH)
photonic waveguide arrays and construct a topological phase diagram by
calculating all bulk Chern numbers, and then explore the bulk-edge
correspondence by analyzing the topological edge states and their winding
numbers. In contrast to incommensurate AAH models, diagonal and off-diagonal
commensurate AAH models are not topologically equivalent. In particular, there
appear nontrivial topological phases with large Chern numbers and topological
phase transitions. By implementing Thouless pumping of light in photonic
waveguide arrays, we propose a simple scheme to measure the bulk Chern numbers.


title: Pattern formation in skyrmionic materials with anisotropic environments

abstract:
  Magnetic skyrmions have attracted broad attention during recent years because
they are regarded as promising candidates as bits of information in novel data
storage devices. A broad range of theoretical and experimental investigations
have been conducted with the consideration of rotational symmetric skyrmions in
isotropic environments. However, one naturally observes a huge variety of
anisotropic behavior in many experimentally relevant materials. In the present
work, we investigate the influence of anisotropic environments onto the
formation and behavior of the non-collinear spin states of skyrmionic materials
by means of Monte-Carlo calculations. We find skyrmionic textures which are far
from having a rotational symmetric shape. Furthermore, we show the possibility
to employ periodic modulations of the environment to create skyrmionic tracks.


title: Photographic dataset: random peppercorns

abstract:
  This is a photographic dataset collected for testing image processing
algorithms. The idea is to have sets of different but statistically similar
images. In this work the images show randomly distributed peppercorns. The
dataset is made available at www.fips.fi/photographic_dataset.php .


title: Korn's inequality and John domains

abstract:
  It is quite well known that Korn's inequality is true on all John domains. We
are interested in the converse implication under assumption of so called
separation condition of the domain. Our result implies that in a simply
connected planar domain the Korn's inequality holds if and only if the domain
is John. In particular, we obtain the equivalence of Korn's inequality, Babu\v
ska-Aziz inequality and Friedrich's inequality in simply connected planar
domains.


title:
Multiwavelength study of the flaring activity of Sgr A* in 2014
  February-April

abstract:
  The supermassive black hole Sgr A* is located at the Milky Way center. We
studied its flaring activity close to the DSO/G2 pericenter passage to
constrain the physical properties and origin of the flares.
Simultaneous/coordinated observations were made in 2014 Feb-Apr with
XMM-Newton, HST/WFC3, VLT/SINFONI, VLA and CARMA. We detected 2 X-ray and 3 NIR
flares on Mar. 10 and Apr. 2 with XMM-Newton and HST and 2 NIR flares on Apr. 3
and 4 with VLT. The Mar. 10 X-ray flare has a long rise and a rapid decay. Its
NIR counterpart peaked 4320s before the X-ray peak implying a variation in the
X-ray-to-NIR flux ratio. This flare may be a single flare where change in the
flux ratio is explained by the adiabatic compression of a plasmon or 2 close
flares with simultaneous X-ray/NIR peaks. We observed an increase in the rising
radio flux density on Mar. 10 with the VLA. It could be the delayed emission
from a NIR/X-ray flare preceding our observation. The Apr. 2 X-ray flare
occurred for HST in the Earth occultation of Sgr A*. We thus only observed the
start of its NIR counterpart. After the occultation, we observed the decay
phase of a bright NIR flare with no X-ray counterpart. On Apr. 3, 2 CARMA
flares were observed. The 1rst one may be the delayed emission of a VLT NIR
flare. We thus observed 7 NIR flares whose 3 have an X-ray counterpart. We
studied the physical parameters of the flaring region for each NIR flare but
none of the possible radiative processes can be ruled out for the X-ray flares
creation. Our X-ray flaring rate is consistent with those observed in the 2012
Chandra XVP campaign. No increase in the flaring activity was thus triggered
close to the DSO/G2 pericenter passage. Moreover, higher X-ray flaring rates
had already been observed with no increase in the quiescent level. There is
thus no direct link between an X-ray flaring-rate increase and an
accretion-rate change. (abridged)


title: Statistical mechanics approach in the counting of integer partitions

abstract:
  The treatment of the number-theoretical problem of integer partitions within
the approach of statistical mechanics is discussed. Historical overview is
given and known asymptotic results for linear and plane partitions are
reproduced. From numerical analysis of restricted plane partitions an
asymptotic formula is conjectured for an intermediate number of parts.


title:
Observation of a $\gamma$-band based on two-quasiparticle configuration
  in $^{70}$Ge

abstract:
  The structure of $^{70}$Ge has been studied through in-beam gamma ray
spectroscopy. A new band structure is identified that leads to forking of the
ground-state band into two excited bands. Band structures have been
investigated using the microscopic triaxial projected shell model approach. The
observed forking is demonstrated to result from almost simultaneous band
crossing of the two neutron aligned and the \gamma-band built on this
two-quasiparticle configuration with the ground-state band.


title:
The vanishing discount problem and viscosity Mather measures. Part 1:
  the problem on a torus

abstract:
  We develop a variational approach to the vanishing discount problem for fully
nonlinear, degenerate elliptic, partial differential equations. Under mild
assumptions, we introduce viscosity Mather measures for such partial
differential equations, which are natural extensions of the Mather measures.
Using the viscosity Mather measures, we prove that the whole family of
solutions $v^\lambda$ of the discount problem with the factor $\lambda>0$
converges to a solution of the ergodic problem as $\lambda \to 0$.


title:
Spectral analysis of non-self-adjoint Jacobi operator associated with
  Jacobian elliptic functions

abstract:
  We perform the spectral analysis of a family of Jacobi operators $J(\alpha)$
depending on a complex parameter $\alpha$. If $|\alpha|\neq1$ the spectrum of
$J(\alpha)$ is discrete and formulas for eigenvalues and eigenvectors are
established in terms of elliptic integrals and Jacobian elliptic functions. If
$|\alpha|=1$, $\alpha \neq \pm 1$, the essential spectrum of $J(\alpha)$ covers
the entire complex plane. In addition, a formula for the Weyl $m$-function as
well as the asymptotic expansions of solutions of the difference equation
corresponding to $J(\alpha)$ are obtained. Finally, the completeness of
eigenvectors and Rodriguez-like formulas for orthogonal polynomials, studied
previously by Carlitz, are proved.


title:
From Classical Nonlinear Integrable Systems to Quantum Shortcuts to
  Adiabaticity

abstract:
  Using shortcuts to adiabaticity, we solve the time-dependent Schroedinger
equation that is reduced to a classical nonlinear integrable equation. For a
given time-dependent Hamiltonian, the counterdiabatic term is introduced to
prevent nonadiabatic transitions. Using the fact that the equation for the
dynamical invariant is equivalent to the Lax equation in nonlinear integrable
systems, we obtain the counterdiabatic term exactly. The counterdiabatic term
is available when the corresponding Lax pair exists and the solvable systems
are classified in a unified and systematic way. Multisoliton potentials
obtained from the Korteweg-de Vries equation and isotropic XY spin chains from
the Toda equations are studied in detail.


title: Dynamics of Localized Structures in Systems with Broken Parity Symmetry

abstract:
  A great variety of nonlinear dissipative systems are known to host structures
having a correlation range much shorter than the size of the system. The
dynamics of these Localized Structures (LSs) have been investigated so far in
situations featuring parity symmetry. In this letter we extend this analysis to
systems lacking of this property. We show that the LS drifting speed in a
parameter varying landscape is not simply proportional to the parameter
gradient, as found in parity preserving situations. The symmetry breaking
implies a new contribution to the velocity field which is a function of the
parameter value, thus leading to a new paradigm for LSs manipulation. We
illustrate this general concept by studying the trajectories of the LSs found
in a passively mode-locked laser operated in the localization regime. Moreover,
the lack of parity affects significantly LSs interactions which are governed by
asymmetrical repulsive forces.


title: Feedback Control of Real-Time Display Advertising

abstract:
  Real-Time Bidding (RTB) is revolutionising display advertising by
facilitating per-impression auctions to buy ad impressions as they are being
generated. Being able to use impression-level data, such as user cookies,
encourages user behaviour targeting, and hence has significantly improved the
effectiveness of ad campaigns. However, a fundamental drawback of RTB is its
instability because the bid decision is made per impression and there are
enormous fluctuations in campaigns' key performance indicators (KPIs). As such,
advertisers face great difficulty in controlling their campaign performance
against the associated costs. In this paper, we propose a feedback control
mechanism for RTB which helps advertisers dynamically adjust the bids to
effectively control the KPIs, e.g., the auction winning ratio and the effective
cost per click. We further formulate an optimisation framework to show that the
proposed feedback control mechanism also has the ability of optimising campaign
performance. By settling the effective cost per click at an optimal reference
value, the number of campaign's ad clicks can be maximised with the budget
constraint. Our empirical study based on real-world data verifies the
effectiveness and robustness of our RTB control system in various situations.
The proposed feedback control mechanism has also been deployed on a commercial
RTB platform and the online test has shown its success in generating
controllable advertising performance.


title:
A novel and automatic pectoral muscle identification algorithm for
  mediolateral oblique (MLO) view mammograms using ImageJ

abstract:
  Pectoral muscle identification is often required for breast cancer risk
analysis, such as estimating breast density. Traditional methods are
overwhelmingly based on manual visual assessment or straight line fitting for
the pectoral muscle boundary, which are inefficient and inaccurate since
pectoral muscle in mammograms can have curved boundaries.
  This paper proposes a novel and automatic pectoral muscle identification
algorithm for MLO view mammograms. It is suitable for both scanned film and
full field digital mammograms. This algorithm is demonstrated using a public
domain software ImageJ. A validation of this algorithm has been performed using
real-world data and it shows promising result.


title:
Amplitude Function of Asymptotic Correlations Along Charged Wall in
  Coulomb Fluids

abstract:
  In classical semi-infinite Coulomb fluids, two-point correlation functions
exhibit a slow inverse-power law decay along a uniformly charged wall. In this
work, we concentrate on the corresponding amplitude function which depends on
the distances of the two points from the wall. Recently [L. \v{S}amaj, J. Stat.
Phys. {\bf 161}, 227 (2015)], applying a technique of anticommuting variables
to a 2D system of charged rectilinear wall with "counter-ions only", we derived
a relation between the amplitude function and the density profile which holds
for any temperature. In this paper, using the M\"obius conformal transformation
of particle coordinates in a disc, a new relation between the amplitude
function and the density profile is found for that model. This enables us to
prove, at any temperature, the factorization property of the amplitude function
in point distances from the wall and to express it in terms of the density
profile. Presupposing the factorization property of the amplitude function and
using specific sum rules for semi-infinite geometries, a relation between the
amplitude function of the charge-charge structure function and the charge
profile is derived for many-component Coulomb fluids in any dimension.


title: Rich square-free words

abstract:
  A word w is rich if it has |w|+1 many distinct palindromic factors, including
the empty word. A word is square-free if it does not have a factor uu, where u
is a non-empty word.
  Pelantov\'a and Starosta (Discrete Math. 313 (2013)) proved that every
infinite rich word contains a square. We will give another proof for that
result. Pelantov\'a and Starosta denoted by r(n) the length of a longest rich
square-free word on an alphabet of size n. The exact value of r(n) was left as
an open question. We will give an upper and a lower bound for r(n), and make a
conjecture that our lower bound is exact.
  We will also generalize the notion of repetition threshold for a limited
class of infinite words. The repetition thresholds for episturmian and rich
words are left as an open question.


title: On BIBO stability of systems with irrational transfer function

abstract:
  We consider the input/output-stability of linear time-invariant
single-input/single-output systems in terms of singularities of the transfer
function F(s) in Laplace domain. The approach is based on complex analysis. A
fairly general class of transfer functions F(s) is considered which can roughly
be characterized by two properties: (1) F(s) is meromorphic with a finite
number of poles in the open right half plane and (2), on the imaginary axes,
F(s) may have at most a finite number of poles and branch points. For this
class of systems, a complete and thorough characterization of BIBO stability in
terms of the singularities in the closed right half-plane is developed where no
necessity arises to differentiate between commensurate and incommensurate
orders of branch points as often done in literature. A necessary and sufficient
condition for BIBO stability is derived which mainly relies on the asymptotic
expansion of the impulse response f(t). The second main result is the
generalization of the well-known Nyquist citerion for testing closed-loop
stability in terms of the open-loop frequency response locus to the class of
systems under consideration which is gained by applying Cauchy's argument
principle.


title:
Yes-no Bloom filter: A way of representing sets with fewer false
  positives

abstract:
  The Bloom filter (BF) is a space efficient randomized data structure
particularly suitable to represent a set supporting approximate membership
queries. BFs have been extensively used in many applications especially in
networking due to their simplicity and flexibility. The performances of BFs
mainly depends on query overhead, space requirements and false positives. The
aim of this paper is to focus on false positives. Inspired by the recent
application of the BF in a novel multicast forwarding fabric for information
centric networks, this paper proposes the yes-no BF, a new way of representing
a set, based on the BF, but with significantly lower false positives and no
false negatives. Although it requires slightly more processing at the stage of
its formation, it offers the same processing requirements for membership
queries as the BF. After introducing the yes-no BF, we show through
simulations, that it has better false positive performance than the BF.


title:
Constraining the physical structure of the inner few 100 AU scales of
  deeply embedded low-mass protostars

abstract:
  (Abridged) The physical structure of deeply-embedded low-mass protostars
(Class 0) on scales of less than 300 AU is still poorly constrained.
Determining this is crucial for understanding the physical and chemical
evolution from cores to disks. In this study two models of the emission, a
Gaussian disk intensity distribution and a parametrized power-law disk model,
are fitted to sub-arcsecond resolution interferometric continuum observations
of five Class 0 sources, including one source with a confirmed Keplerian disk.
For reference, a spherically symmetric single power-law envelope is fitted to
the larger scale ($\sim$1000 AU) emission and investigated further for one of
the sources on smaller scales. A thin disk model can approximate the emission
and physical structure in the inner few 100 AU scales of the studied
deeply-embedded low-mass protostars and paves the way for analysis of a larger
sample with ALMA. While the disk radii agree with previous estimates the masses
are different for some of the sources studied. Assuming a typical temperature
distribution, the fractional amount of mass in the disk above 100 K varies in
between 7% to 30%. Kinematic data are needed to determine the presence of any
Keplerian disk. Using previous observations of p-H$_2^{18}$O, we estimate the
relative gas phase water abundances roughly an order of magnitude higher than
previously inferred when both warm and cold H$_2$ was used as reference. A
spherically symmetric single power-law envelope model fails to simultaneously
reproduce both the small and large scale emission.


title:
Equilibria in a competitive model arising from linear production
  situations with a common-pool resource

abstract:
  In this paper we deal with linear production situations in which there is a
limited common-pool resource, managed by an external agent. The profit that a
producer, or a group of producers, can attain depends on the amount of
common-pool resource obtained through a certain procedure. We contemplate a
competitive process among the producers or groups of producers and study the
corresponding non cooperative games, describing their (strict) Nash equilibria
in pure strategies. It is shown that strict Nash equilibria form a subset of
strong Nash equilibria, which in turn form a proper subset of Nash equilibria.


title:
Staircase Quantum Dots Configuration in Nanowires for Optimized
  Thermoelectric Power

abstract:
  The performance of thermoelectric energy harvesters can be improved by
nanostructures that exploit inelastic transport processes. One prototype is the
three-terminal hopping thermoelectric device where electron hopping between
quantum-dots are driven by hot phonons. Such three-terminal hopping
thermoelectric devices have potential in achieving high efficiency or power via
inelastic transport and without relying on heavy-elements or toxic compounds.
We show in this work how output power of the device can be optimized via tuning
the number and energy configuration of the quantum-dots embedded in parallel
nanowires. We find that the staircase energy configuration with constant
energy-step can improve the power factor over a serial connection of a single
pair of quantum-dots. Moreover, for a fixed energy-step, there is an optimal
length for the nanowire. Similarly for a fixed number of quantum-dots there is
an optimal energy-step for the output power. Our results are important for
future developments of high-performance nanostructured thermoelectric devices.


title:
Far-field resonance fluorescence from a dipole-interacting laser-driven
  cold atomic gas

abstract:
  We analyze the temporal response of the fluorescence light that is emitted
from a dense gas of cold atoms driven by a laser. When the average interatomic
distance is smaller than the wavelength of the photons scattered by the atoms,
the system exhibits strong dipolar interactions and collective dissipation. We
solve the exact dynamics of small systems with different geometries and show
how these collective features are manifest in the scattered light properties
such as the photon emission rate, the power spectrum and the second-order
correlation function. By calculating these quantities beyond the weak driving
limit, we make progress in understanding the signatures of collective behavior
in these many-body systems. Furthermore, we clarify the role of disorder on the
resonance fluorescence, of direct relevance for recent experimental efforts
that aim at the exploration of many-body effects in dipole-dipole interacting
gases of atoms.


title:
Probe of the Anomalous Quartic Couplings with Beam Polarization at the
  CLIC

abstract:
  We have investigated the anomalous quartic couplings defined by the
dimension-8 operators in semileptonic decay channel of the
$e^{+}e^{-}\rightarrow \nu_{e} W^{-} W^{+} \bar{\nu}_{e}$ process for
unpolarized and polarized electron (positron) beam at the Compact Linear
Collider. We give the $95\%$ confidence level bounds on anomalous
$\frac{f_{S0}}{\Lambda^{4}}$, $\frac{f_{S1}}{\Lambda^{4}}$ and
$\frac{f_{T0}}{\Lambda^{4}}$ couplings for various values of the integrated
luminosities and center-of-mass energies. The best sensitivities obtained on
anomalous $\frac{f_{S0}}{\Lambda^{4}}$, $\frac{f_{S1}}{\Lambda^{4}}$ and
$\frac{f_{T0}}{\Lambda^{4}}$ couplings through the process
$e^{+}e^{-}\rightarrow \nu_{e} W^{-} W^{+} \bar{\nu}_{e}$ with beam
polarization at $\sqrt{s}=3$ TeV and an integrated luminosity of $L_{int}=2000$
fb$^{-1}$ are $[-4.05;\, 3.67]\times 10^{-12}$ GeV$^{-4}$, $[-3.08; \,
2.12]\times 10^{-12}$ GeV$^{-4}$, $[-1.98; \, 0.64]\times 10^{-13}$ GeV$^{-4}$,
which show improvement over the current bounds.


title:
What we look at in paintings: A comparison between experienced and
  inexperienced art viewers

abstract:
  How do people look at art? Are there any differences between how experienced
and inexperienced art viewers look at a painting? We approach these questions
by analyzing and modeling eye movement data from a cognitive art research
experiment, where the eye movements of twenty test subjects, ten experienced
and ten inexperienced art viewers, were recorded while they were looking at
paintings.
  Eye movements consist of stops of the gaze as well as jumps between the
stops. Hence, the observed gaze stop locations can be thought as a spatial
point pattern, which can be modeled by a spatio-temporal point process. We
introduce some statistical tools to analyze the spatio-temporal eye movement
data, and compare the eye movements of experienced and inexperienced art
viewers. In addition, we develop a stochastic model, which is rather simple but
fits quite well to the eye movement data, to further investigate the
differences between the two groups through functional summary statistics.


title:
Modeling the Sequence of Brain Volumes by Local Mesh Models for Brain
  Decoding

abstract:
  We represent the sequence of fMRI (Functional Magnetic Resonance Imaging)
brain volumes recorded during a cognitive stimulus by a graph which consists of
a set of local meshes. The corresponding cognitive process, encoded in the
brain, is then represented by these meshes each of which is estimated assuming
a linear relationship among the voxel time series in a predefined locality.
First, we define the concept of locality in two neighborhood systems, namely,
the spatial and functional neighborhoods. Then, we construct spatially and
functionally local meshes around each voxel, called seed voxel, by connecting
it either to its spatial or functional p-nearest neighbors. The mesh formed
around a voxel is a directed sub-graph with a star topology, where the
direction of the edges is taken towards the seed voxel at the center of the
mesh. We represent the time series recorded at each seed voxel in terms of
linear combination of the time series of its p-nearest neighbors in the mesh.
The relationships between a seed voxel and its neighbors are represented by the
edge weights of each mesh, and are estimated by solving a linear regression
equation. The estimated mesh edge weights lead to a better representation of
information in the brain for encoding and decoding of the cognitive tasks. We
test our model on a visual object recognition and emotional memory retrieval
experiments using Support Vector Machines that are trained using the mesh edge
weights as features. In the experimental analysis, we observe that the edge
weights of the spatial and functional meshes perform better than the
state-of-the-art brain decoding models.


title:
First Steps Toward Camera Model Identification with Convolutional Neural
  Networks

abstract:
  Detecting the camera model used to shoot a picture enables to solve a wide
series of forensic problems, from copyright infringement to ownership
attribution. For this reason, the forensic community has developed a set of
camera model identification algorithms that exploit characteristic traces left
on acquired images by the processing pipelines specific of each camera model.
In this paper, we investigate a novel approach to solve camera model
identification problem. Specifically, we propose a data-driven algorithm based
on convolutional neural networks, which learns features characterizing each
camera model directly from the acquired pictures. Results on a well-known
dataset of 18 camera models show that: (i) the proposed method outperforms
up-to-date state-of-the-art algorithms on classification of 64x64 color image
patches; (ii) features learned by the proposed network generalize to camera
models never used for training.


title:
The first X-ray imaging spectroscopy of quiescent solar active regions
  with NuSTAR

abstract:
  We present the first observations of quiescent active regions (ARs) using
NuSTAR, a focusing hard X-ray telescope capable of studying faint solar
emission from high temperature and non-thermal sources. We analyze the first
directly imaged and spectrally resolved X-rays above 2~keV from non-flaring
ARs, observed near the west limb on 2014 November 1. The NuSTAR X-ray images
match bright features seen in extreme ultraviolet and soft X-rays. The NuSTAR
imaging spectroscopy is consistent with isothermal emission of temperatures
$3.1-4.4$~MK and emission measures $1-8\times 10^{46}$~cm$^{-3}$. We do not
observe emission above 5~MK but our short effective exposure times restrict the
spectral dynamic range. With few counts above 6~keV, we can place constraints
on the presence of an additional hotter component between 5 and 12~MK of $\sim
10^{46}$cm$^{-3}$ and $\sim 10^{43}$ cm$^{-3}$, respectively, at least an order
of magnitude stricter than previous limits. With longer duration observations
and a weakening solar cycle (resulting in an increased livetime), future NuSTAR
observations will have sensitivity to a wider range of temperatures as well as
possible non-thermal emission.


title: Relaxed concentrated MLE for robust calibration of radio interferometers

abstract:
  In this paper, we investigate the calibration of radio interferometers in
which Jones matrices are considered to model the interaction between the
incident electromagnetic field and the antennas of each station. Specifically,
perturbation effects are introduced along the signal path, leading to the
conversion of the plane wave into an electric voltage by the receptor. In order
to design a robust estimator, the noise is assumed to follow a spherically
invariant random process (SIRP). The derived algorithm is based on an iterative
relaxed concentrated maximum likelihood estimator (MLE), for which closed-form
expressions are obtained for most of the unknown parameters.


title: Many-particle dephasing after a quench

abstract:
  After a quench in a quantum many-body system, expectation values tend to
relax towards long-time averages. However, in any finite-size system, temporal
fluctuations remain. It is crucial to study the suppression of these
fluctuations with system size. The particularly important case of
non-integrable models has been addressed so far only by numerics and
conjectures based on analytical bounds. In this work, we are able to derive
analytical predictions for the temporal fluctuations in a non-integrable model
(the transverse Ising chain with extra terms). Our results are based on
identifying a dynamical regime of 'many-particle dephasing', where
quasiparticles do not yet relax but fluctuations are nonetheless suppressed
exponentially by weak integrability breaking.


title:
Effect of the $2p2h$ cross-section uncertainties on an analysis of
  neutrino oscillations

abstract:
  We report the results of a study aimed at quantifying the impact on the
oscillation analysis of the uncertainties associated with the description of
the neutrino-nucleus cross section in the two-particle--two-hole sector. The
results of our calculations, based on the kinematic method of energy
reconstruction and carried out comparing two data-driven approaches, show that
the existing discrepancies in the neutrino cross sections have a sizable effect
on the extracted oscillation parameters, particularly in the antineutrino
channel.


title:
Retarding the growth of the {Rosensweig} instability unveils a new
  scaling regime

abstract:
  Using a highly viscous magnetic fluid, the dynamics in the aftermath of the
Rosensweig instability can be slowed down by more than 2000 times. In this way
we expand the regime where the growth rate is predicted to scale linearly with
the bifurcation parameter by six orders of magnitude, while this regime is tiny
for standard ferrofluids and can not be resolved experimentally there. We
measure the growth of the pattern by means of a two-dimensional imaging
technique, and find that the slopes of the growth and decay rates are not the
same - a qualitative discrepancy to the theoretical predictions. We solve this
discrepancy by taking into account a viscosity which is assumed to be different
for the growth and decay. This may be a consequence of the measured shear
thinning of the ferrofluid.


title:
Numerical analysis of the Oseen-type Peterlin viscoelastic model by the
  stabilized Lagrange-Galerkin method, Part II: A linear scheme

abstract:
  This is the second part of our error analysis of the stabilized
Lagrange-Galerkin scheme applied to the Oseen-type Peterlin viscoelastic model.
Our scheme is a combination of the method of characteristics and
Brezzi-Pitk\"aranta's stabilization method for the conforming linear elements,
which leads to an efficient computation with a small number of degrees of
freedom especially in three space dimensions. In this paper, Part II, we apply
a semi-implicit time discretization which yields the linear scheme. We
concentrate on the diffusive viscoelastic model, i.e. in the constitutive
equation for time evolution of the conformation tensor a diffusive effect is
included. Under mild stability conditions we obtain error estimates with the
optimal convergence order for the velocity, pressure and conformation tensor in
two and three space dimensions. The theoretical convergence orders are
confirmed by numerical experiments.


title:
Periodic solutions of Euler-Lagrange equations with sublinear
  pontentials in an Orlicz-Sobolev space setting

abstract:
  In this paper, we obtain existence results of periodic solutions of
hamiltonian systems in the Orlicz-Sobolev space $W^1L^{\Phi}([0,T])$. We employ
the direct method of calculus of variations and we consider a potential
function $F$ satisfying the inequality $|\nabla F(t,x)|\leq b_1(t)
\Phi_0'(|x|)+b_2(t)$, with $b_1, b_2\in L^1$ and certain $N$-functions
$\Phi_0$.


title: What is the right way to represent document images?

abstract:
  In this article we study the problem of document image representation based
on visual features. We propose a comprehensive experimental study that compares
three types of visual document image representations: (1) traditional so-called
shallow features, such as the RunLength and the Fisher-Vector descriptors, (2)
deep features based on Convolutional Neural Networks, and (3) features
extracted from hybrid architectures that take inspiration from the two previous
ones.
  We evaluate these features in several tasks (i.e. classification, clustering,
and retrieval) and in different setups (e.g. domain transfer) using several
public and in-house datasets. Our results show that deep features generally
outperform other types of features when there is no domain shift and the new
task is closely related to the one used to train the model. However, when a
large domain or task shift is present, the Fisher-Vector shallow features
generalize better and often obtain the best results.


title:
Functional Connectivity in Default Mode Network During Resting State: An
  Evaluation of the Effects of Data Pre-processing

abstract:
  Resting state functional connectivity estimates from MRI measures has become
a promising tool to characterize human brain networks. There are, however,
limitations in the method since several sources of errors have been seen to
significantly affect the final estimates. This has lead to a great interest in
the field to do systematic investigations that help determine the most reliable
and robust strategies to perform functional connectivity analysis. In the
present study, we examine the influence of two aspects of data pre- processing
in resting state functional connectivity analysis: the effect of criteria used
to select nodes in the default mode network (DMN) for the computation of
connectivity, and the effect of using or not physiological noise correction.
Three different strategies of region of interest (ROI) selection were compared
to define DMN node coordinates: (1) ROIs centered on atlas-based coordinates,
(2) ROIs based on the result of group independent component analysis, and (3)
ROIs based on the estimated DMN of each individual. The study was done using
data of 15 healthy volunteers, which had resting state data available from a
separate project. We found that both effects, ROI selection criteria for DMN
nodes and physiological noise correction, have significant effects on the
functional connectivity estimates. In particular, our results show that
physiological noise correction introduces small but significant reductions in
functional connectivity, consistent with a reduction of artifactual non-neural
correlations introduced by physiological effects. Further, selecting DMN nodes
based on the single subject ICA results introduced small but significant
increases in functional connectivity, consistent with higher subject
specificity of the node selection.


title: Homogeneous numerical semigroups

abstract:
  We introduce the concept of homogeneous numerical semigroups and show that
all homogeneous numerical semigroups with Cohen-Macaulay tangent cones are of
homogeneous type. In embedding dimension three, we classify all numerical
semigroups of homogeneous type in to numerical semigroups with complete
intersection tangent cones and the homogeneous ones with Cohen-Macaulay tangent
cones. We also study the behavior of the homogeneous property by gluing and
shiftings to construct a large family of homogeneous numerical semigroups with
Cohen-Macaulay tangent cones. In particular we show that these properties
fulfill assymptotically in the shifting classes. Several explicit examples are
provided along the paper to illustrate the property.


title: The Elliptic Function in Statistical Integrable Models

abstract:
  We examine the group theoretical reason why various two dimensional
statistical integrable models, such as the Ising model, the chiral Potts model
and the Belavin model, becomes integrable. The symmetry of these integrable
models is SU(2) and the Boltzmann weight can be parametrized by the elliptic
function in many cases. In this paper, we examine the connection between the
SU(2) symmetry and the elliptic function in the statistical integrable models.


title:
Spectrum Pooling in MmWave Networks: Opportunities, Challenges, and
  Enablers

abstract:
  Motivated by the intrinsic characteristics of mmWave technologies, we discuss
the possibility of an authorization regime that allows spectrum sharing between
multiple operators, also referred to as spectrum pooling. In particular,
considering user rate as the performance measure, we assess the benefit of
coordination among the networks of different operators, study the impact of
beamforming both at the base stations and at the user terminals, and analyze
the pooling performance at different frequency carriers. We also discuss the
enabling spectrum mechanisms, architectures, and protocols required to make
spectrum pooling work in real networks. Our initial results show that, from a
technical perspective, spectrum pooling at mmWave has the potential for a more
efficient spectrum use than a traditional exclusive spectrum allocation to a
single operator. However, further studies are needed in order to reach a
thorough understanding of this matter, and we hope that this paper will help
stimulate further research in this area.


title: Beta-expansion and continued fraction expansion of real numbers

abstract:
  Let $\beta > 1$ be a real number and $x \in [0,1)$ be an irrational number.
We denote by $k_n(x)$ the exact number of partial quotients in the continued
fraction expansion of $x$ given by the first $n$ digits in the
$\beta$-expansion of $x$ ($n \in \mathbb{N}$). It is known that $k_n(x)/n$
converges to $(6\log2\log\beta)/\pi^2$ almost everywhere in the sense of
Lebesgue measure. In this paper, we improve this result by proving that the
Lebesgue measure of the set of $x \in [0,1)$ for which $k_n(x)/n$ deviates away
from $(6\log2\log\beta)/\pi^2$ decays to 0 exponentially as $n$ tends to
$\infty$, which generalizes the result of Faivre \cite{lesFai97} from $\beta =
10$ to any $\beta >1$. Moreover, we also discuss which of the $\beta$-expansion
and continued fraction expansion yields the better approximations of real
numbers.


title:
Formal Specification and Analysis of Autonomous Systems under Partial
  Compliance

abstract:
  The widespread adoption of autonomous systems depends on providing guarantees
of safety and functional correctness, at both design time and runtime.
Information about the extent to which functional requirements can be met in
combination with non-functional requirements (NFRs) -- i.e. requirements that
can be partially complied with -- , under dynamic and uncertain environments,
provides opportunities to enhance the safety and functional correctness of
systems at design time. We present a technique to formally define system
attributes that can change or be changed to deal with dynamic and uncertain
environments (denominated weakened specifications) as a partially ordered
lattice, and to automatically explore the system under different
specifications, using probabilistic model checking, to find the likelihood of
satisfying a requirement. The resulting probabilities form boundaries of
"optimal specifications", analogous to Pareto frontiers in multi-objective
optimization, informing the designer about the system's capabilities, such as
resilience or robustness, when changing its attributes to deal with dynamic and
uncertain environments. We illustrate the proposed technique through a domestic
robotic assistant example.


title: Role of explosive instabilities in high-$\beta$ disruptions in tokamaks

abstract:
  Intrinsically explosive growth of a ballooning finger is demonstrated in
nonlinear magnetohydrodynamic calculations of high-$\beta$ disruptions in
tokamaks. The explosive finger is formed by an ideally unstable n=1 mode,
dominated by an m/n=2/1 component. The quadrupole geometry of the 2/1 perturbed
pressure field provides a generic mechanism for the formation of the initial
ballooning finger and its subsequent transition from exponential to explosive
growth, without relying on secondary processes. The explosive ejection of the
hot plasma from the core and stochastization of the magnetic field occur in
Alfv\'enic time scales, accounting for the extremely fast growth of the
precursor oscillations and the rapidity of the thermal quench in some
high-$\beta$ disruptions.


title:
Typical pure nonequilibrium steady states and irreversibility for
  quantum transports

abstract:
  It is known that each single typical pure state in an energy shell of a large
isolated quantum system well represents a thermal equilibrium state of the
system. We show that such typicality holds also for nonequilibrium steady
states (NESS's). We consider a small quantum system coupled to multiple
infinite reservoirs. In the long run, the total system reaches a unique NESS.
We identify a large Hilbert space from which pure states of the system are to
be sampled randomly and show that the typical pure states well describe the
NESS. We also point out that the irreversible relaxation to the unique NESS is
important to the typicality of the pure NESS's.


title: On Kapteyn-Kummer Series' Integral Form

abstract:
  In this short research note we obtain double definite integral expressions
for the Kapteyn type series built by Kummer's $M$ (or confluent hypergeometric
${}_1F_1$) functions. These kind of series unify in natural way the similar
fashion results for Neumann-, Schl\"omilch- and Kapteyn-Bessel series recently
established by Pog\'any, S\"uli, Baricz and Jankov Ma\v{s}irevi\'c.


title: Pi01 encodability and omniscient reductions

abstract:
  A set of integers $A$ is computably encodable if every infinite set of
integers has an infinite subset computing $A$. By a result of Solovay, the
computably encodable sets are exactly the hyperarithmetic ones. In this paper,
we extend this notion of computable encodability to subsets of the Baire space
and we characterize the $\Pi^0_1$ encodable compact sets as those who admit a
non-empty $\Sigma^1_1$ subset. Thanks to this equivalence, we prove that weak
weak K\"onig's lemma is not strongly computably reducible to Ramsey's theorem.
This answers a question of Hirschfeldt and Jockusch.


title: Compilation of spectroscopic data of Radium (Ra I and Ra II)

abstract:
  Energy levels, wavelengths, lifetimes and hyperfine structure constants for
the isotopes of the first and second spectra of radium, Ra I and Ra II have
been compiled. Wavelengths and wave numbers are tabulated for 226Ra and for
other Ra isotopes. Isotope shifts and hyperfine structure constants of even and
odd-A isotopes of neutral radium atom and singly ionized radium are included.
Experimental lifetimes of the states for both neutral and ionic Ra are also
added, where available. The information is beneficial for present and future
experiments aimed at different physics motivations using neutral Ra and singly
ionized Ra.


title:
The critical mass ratio of double white dwarf binaries for violent
  merger-induced Type Ia supernova explosions

abstract:
  Mergers of carbon-oxygen (CO) white dwarfs (WDs) are considered as one of the
potential progenitors of type Ia supernovae (SNe Ia). Recent hydrodynamical
simulations showed that the less massive (secondary) WD violently accretes onto
the more massive (primary) one, carbon detonation occurs, the detonation wave
propagates through the primary, and the primary finally explodes as a
sub-Chandrasekhar mass SN Ia. Such an explosion mechanism is called the violent
merger scenario. Based on the smoothed particle hydrodynamics (SPH) simulations
of merging CO WDs, we derived more stringent critical mass ratio (qcr) leading
to the violent merger scenario than the previous results. We conclude that this
difference mainly comes from the differences in the initial condition,
synchronously spinning of WDs or not. Using our new results, we estimated the
brightness distribution of SNe Ia in the violent merger scenario and compared
it with previous studies. We found that our new qcr does not significantly
affect the brightness distribution. We present the direct outcome immediately
following CO WD mergers for various primary masses and mass ratios. We also
discussed the final fate of the central system of the bipolar planetary nebula
Henize 2-428, which was recently suggested to be a double CO WD system whose
total mass exceeds the Chandrasekhar-limiting mass, merging within the Hubble
time. Even considering the uncertainties in the proposed binary parameters, we
concluded that the final fate of this system is almost certainly a
sub-Chandrasekhar mass SN Ia in the violent merger scenario.


title: Impulse-induced localized control of chaos in starlike networks

abstract:
  Locally decreasing the impulse transmitted by periodic pulses is shown to be
a reliable method of taming chaos in starlike networks of dissipative nonlinear
oscillators, leading to both synchronous periodic states and equilibria
(oscillation death). Specifically, the paradigmatic model of damped kicked
rotators is studied in which it is assumed that when the rotators are driven
synchronously, i.e., all driving pulses transmit the same impulse, the networks
display chaotic dynamics. It is found that the taming effect of decreasing the
impulse transmitted by the pulses acting on particular nodes strongly depends
on their number and degree of connectivity. A theoretical analysis is given
explaining the basic physical mechanism as well as the main features of the
chaos-control scenario.


title:
Using Newton's method to model a spatial light distribution of a LED
  with attached secondary optics

abstract:
  In design of optical systems based on LED (Light emitting diode) technology,
a crucial task is to handle the unstructured data describing properties of
optical elements in standard formats. This leads to the problem of data fitting
within an appropriate model. Newton's method is used as an upgrade of
previously developed most promising discrete optimization heuristics showing
improvement of both performance and quality of solutions. Experiment also
indicates that a combination of an algorithm that finds promising initial
solutions as a preprocessor to Newton's method may be a winning idea, at least
on some datasets of instances.


title:
Universality of Composition Operators and Applications to Holomorphic
  Dynamics

abstract:
  By investigating which level of universality composition operators $C_f$ can
have, where the symbol $f$ is given by the restriction of a transcendental
entire function to suitable parts of the Fatou set of $f$, this work combines
the theory of dynamics of continuous linear operators on spaces of holomorphic
functions with the theory of non-linear complex dynamics on the complex plane.


title:
Integral representations in supermanifolds: super Hodge duals, PCOs and
  Liouville forms

abstract:
  We present few types of integral transforms and integral representations that
are very useful for extending to supergeometry many familiar concepts of
differential geometry. Among them we discuss the construction of the super
Hodge dual, the integral representation of picture changing operators of string
theories and the construction of the super-Liouville form of a symplectic
supermanifold.


title:
On a residual freedom of the next-to-leading BFKL eigenvalue in color
  adjoint representation in planar $\mathcal{N} = 4$ SYM

abstract:
  We discuss a residual freedom of the next-to-leading BFKL eigenvalue that
originates from ambiguity in redistributing the next-to-leading~(NLO)
corrections between the adjoint BFKL eigenvalue and eigenfunctions in planar
$\mathcal{N}=4$ super-Yang-Mills~(SYM) Theory. In terms of the remainder
function of the Bern-Dixon-Smirnov~(BDS) amplitude this freedom is translated
to reshuffling correction between the eigenvalue and the impact factors in the
multi-Regge kinematics~(MRK) in the next-to-leading logarithm
approximation~(NLA). We show that the modified NLO BFKL eigenvalue suggested by
the authors can be introduced in the MRK expression for the remainder function
by shifting the anomalous dimension in the impact factor in such a way that the
two and three loop remainder function is left unchanged to the NLA accuracy.


title: Optimal densities of packings consisting of highly unequal objects

abstract:
  Let $\Delta$ be the optimal packing density of $\mathbb R^n$ by unit balls.
We show the optimal packing density using two sizes of balls approaches $\Delta
+ (1 - \Delta) \Delta$ as the ratio of the radii tends to infinity. More
generally, if $B$ is a body and $D$ is a finite set of bodies, then the optimal
density $\Delta_{\{rB\} \cup D}$ of packings consisting of congruent copies of
the bodies from $\{rB\} \cup D$ converges to $\Delta_D + (1 - \Delta_D)
\Delta_{\{B\}}$ as $r$ tends to zero.


title:
Stability for a magnetic Schr\"odinger operator on a Riemann surface
  with boundary

abstract:
  We consider a magnetic Schr\"odinger operator $(\nabla^X)^*\nabla^X+q$ on a
compact Riemann surface with boundary and prove a $\log\log$-type stability
estimate in terms of Cauchy data for the electric potential and magnetic field
under the assumption that they satisfy appropriate a priori bounds. We also
give a similar stability result for the holonomy of the connection 1-form $X$.


title:
Elastic Net Hypergraph Learning for Image Clustering and Semi-supervised
  Classification

abstract:
  Graph model is emerging as a very effective tool for learning the complex
structures and relationships hidden in data. Generally, the critical purpose of
graph-oriented learning algorithms is to construct an informative graph for
image clustering and classification tasks. In addition to the classical
$K$-nearest-neighbor and $r$-neighborhood methods for graph construction,
$l_1$-graph and its variants are emerging methods for finding the neighboring
samples of a center datum, where the corresponding ingoing edge weights are
simultaneously derived by the sparse reconstruction coefficients of the
remaining samples. However, the pair-wise links of $l_1$-graph are not capable
of capturing the high order relationships between the center datum and its
prominent data in sparse reconstruction. Meanwhile, from the perspective of
variable selection, the $l_1$ norm sparse constraint, regarded as a LASSO
model, tends to select only one datum from a group of data that are highly
correlated and ignore the others. To simultaneously cope with these drawbacks,
we propose a new elastic net hypergraph learning model, which consists of two
steps. In the first step, the Robust Matrix Elastic Net model is constructed to
find the canonically related samples in a somewhat greedy way, achieving the
grouping effect by adding the $l_2$ penalty to the $l_1$ constraint. In the
second step, hypergraph is used to represent the high order relationships
between each datum and its prominent samples by regarding them as a hyperedge.
Subsequently, hypergraph Laplacian matrix is constructed for further analysis.
New hypergraph learning algorithms, including unsupervised clustering and
multi-class semi-supervised classification, are then derived. Extensive
experiments on face and handwriting databases demonstrate the effectiveness of
the proposed method.


title:
Scaling Correlations Among Central Massive Objects and Their Host
  Galaxies

abstract:
  The central regions of galaxies show the presence of super massive black
holes and/or very dense stellar clusters. Both such objects seem to follow
similar host-galaxy correlations, suggesting that they are members of the same
family of Compact Massive Objects. Here we investigate a huge data collection
of Compact Massive Objects properties to correlate them with absolute
magnitude, velocity dispersion and mass of their host galaxies. We draw also
some preliminary astrophysical conclusions.


title:
Extension of the energy range of experimental activation cross-sections
  data of deuteron induced nuclear reactions on indium up to 50 MeV

abstract:
  The energy range of our earlier measured activation cross-sections data of
longer-lived products of deuteron induced nuclear reactions on indium were
extended from 40 MeV up to 50 MeV. The traditional stacked foil irradiation
technique and non-destructive gamma spectrometry were used. No experimental
data were found in literature for this higher energy range. Experimental
cross-sections for the formation of the radionuclides $^{113,110}$Sn,
$^{116m,115m,114m,113m,111,110g,109}$In and $^{115}$Cd are reported in the
37-50 MeV energy range, for production of $^{110}$Sn and $^{110g,109}$In these
are the first measurements ever. The experimental data were compared with the
results of cross section calculations of the ALICE and EMPIRE nuclear model
codes and of the TALYS1.6 nuclear model code as listed in the on-line library
TENDL-2014.


title:
Design and characterization of integrated components for SiN photonic
  quantum circuits

abstract:
  The design, fabrication, and detailed calibration of essential building
blocks towards fully integrated linear-optics quantum computation are
discussed. Photonic devices are made from silicon nitride rib waveguides, where
measurements on ring resonators show small propagation losses. Directional
couplers are designed to be insensitive to fabrication variations. Their offset
and coupling lengths are measured, as well as the phase difference between the
transmitted and reflected light. With careful calibrations, the insertion loss
of the directional couplers is found to be small. Finally, an integrated
controlled-NOT circuit is characterized by measuring the transmission through
different combinations of inputs and outputs. The gate fidelity for the CNOT
operation with this circuit is estimated to be 99.81% after post selection.
This high fidelity is due to our robust design, good fabrication
reproducibility, and extensive characterizations.


title: On evolution equations governed by non-autonomous forms

abstract:
  We consider a linear non-autonomous evolutionary Cauchy problem
\begin{equation} \dot{u} (t)+A(t)u(t)=f(t) \hbox{ for }\ \hbox{a.e. t}\in
[0,T],\quad u(0)=u_0, \end{equation} where the operator $A(t)$ arises from a
time depending sesquilinear form $a(t,.,.)$ on a Hilbert space $H$ with
constant domain $V.$ Recently a result on $L^2$-maximal regularity in $H,$
i.e., for each given $f\in L^2(0,T,H)$ and $u_0 \in V$ the problem above has a
unique solution $u\in L^2(0,T,V)\cap H^1(0,T,H),$ is proved in [10] under the
assumption that $a$ is symmetric and of bounded variation. The aim of this
paper is to prove that the solutions of an approximate non-autonomous Cauchy
problem in which $a$ is symmetric and piecewise affine are closed to the
solutions of that governed by symmetric and of bounded variation form. In
particular, this provide an alternative proof of the result in [10] on
$L^2$-maximal regularity in $H.$


title:
Quantitative results on continuity of the spectral factorization mapping
  in the scalar case

abstract:
  In the scalar case, the spectral factorization mapping $f\to f^+$ puts a
nonnegative integrable function $f$ having an integrable logarithm in
correspondence with an outer analytic function $f^+$ such that $f = |f^+|^2$
almost everywhere. The main question addressed here is to what extent $\|f^+ -
g^+\|_{H_2}$ is controlled by $\|f-g\|_{L_1}$ and $\|\log f - \log g\|_{L_1}$.


title:
Implementation of the fast table grid user interface element for working
  with large database tables

abstract:
  Table grid user interface element with a vertical scrollbar is a standard way
of working with database table records. There are two basic operations each
grid should support: scrolling records with vertical scrollbar and positioning
to a record with a given primary key. This paper addresses the case when the
number of records is so large that it is not feasible to load them all into
memory, and database functions like "select..offset" work insufficiently fast
and put undue load on RDBMS. Our main idea is to use only queries that involve
index lookup (a O(Log(N)-fast operation) and to use statistic properties of
hypergeometric distribution to "guess" primary keys of records given their
ordinal numbers. The proposed method allows us to implement a grid with
O(Log(N))-fast scrolling and positioning performance.


title:
Regularities and Discrepancies of Credit Default Swaps: a Data Science
  approach through Benford's Law

abstract:
  In this paper, we search whether the Benford's law is applicable to monitor
daily changes in sovereign Credit Default Swaps (CDS) quotes, which are
acknowledged to be complex systems of economic content. This test is of
paramount importance since the CDS of a country proxy its health and
probability to default, being associated to an insurance against the event of
its default. We fit the Benford's law to the daily changes in sovereign CDS
spreads for 13 European countries, - both inside and outside the European Union
and European Monetary Union. Two different tenors for the sovereign CDS
contracts are considered: 5 yrs and 10 yrs, - the former being the reference
and most liquid one. The time period under investigation is 2008-2015 which
includes the period of distress caused by the European sovereign debt crisis.
Moreover, (i) an analysis over relevant sub-periods is carried out, (ii)
several insights are provided also by implementing the tracking of the
Benford's law over moving windows. The main test for checking the conformance
to Benford's law is - as usual - the $\chi^{2}$ test, whose values are
presented and discussed for all cases. The analysis is further completed by
elaborations based on Chebyshev's distance and Kullback and Leibler's
divergence. The results highlight differences by countries and tenors. In
particular, these results suggest that liquidity seems to be associated to
higher levels of distortion. Greece - representing a peculiar case - shows a
very different path with respect to the other European countries.


title:
Predicted superconductivity of Ni2VAl and pressure dependence of
  superconductivity in Ni2NbX (X = Al, Ga and Sn) and Ni2VAl

abstract:
  A first-principles study of the electronic and superconducting properties of
the Ni$_2$VAl Heusler compound is presented. The electron-phonon coupling
constant of $\lambda_{ep}$ = 0.68 is obtained, which leads to a superconducting
transition temperature of T$_c$ = $\sim$4 $K$ (assuming a Coulomb
pseudopotential $\mu^*$ = 0.13), which is a relatively high transition
temperature for Ni based Heusler alloys. The electronic density of states
reveals a significant hybridization between Ni-$eg$ and V-$t_{2g}$ states
around the Fermi level. The Fermi surface, consisting of two electron pockets
around the X-points of the Brillouin zone, exhibits nesting and leads to a Kohn
anomaly of the phonon dispersion relation for the transverse acoustic mode TA2
along the (1,1,0) direction, which is furthermore found to soften with
pressure. As a consequence, T$_c$ and $\lambda_{ep}$ vary non-monotonically
under pressure. The calculations are compared to similar calculations performed
for the Ni$_2$NbX (X = Al, Ga and Sn) Heusler alloys, which experimentally have
been identified as superconductors. The experimental trend in T$_c$ is well
reproduced, and reasonable quantitative agreement is obtained. The calculated
T$_c$ of Ni$_2$VAl is larger than either calculated and observed T$_c$s of any
of the Nb compounds. The Fermi surfaces of Ni$_2$NbAl and Ni$_2$NbGa consist of
only a single electron pocket around the X point, however under compression
second electron pocket similar to that of Ni2VAl emerges only in Ni2NbAl and
the Tc increases non monotonically in all the compounds. Fermi surface nesting
and associated Kohn anomalies are a common feature of all four compounds,
albeit weakest in Ni$_2$VAl.


title:
Exploring center vortices in SU(2) and SU(3) relativistic
  Yang-Mills-Higgs models

abstract:
  We develop numerical tools and apply them to solve the relativistic
Yang--Mills--Higgs equations in a model where the SU(N) symmetry is
spontaneously broken to its center. In SU(2) and SU(3), we obtain the different
field profiles for infinite and finite center vortices, with endpoints at
external monopole sources. Exploration of parameter space permits the detection
of a region where the equations get Abelianized. Finally, a general
parametrization of the color structure of SU(2) fields leads us to a reference
point where an Abelian-like BPS bound is reconciled with N-ality.


title: Structured Beam Generation with a Single Metasurface

abstract:
  Despite a plethora of applications ranging from quantum memories to
high-resolution lithography, the current technologies to generate vector vortex
beams (VVBs) suffer from less efficient energy use, poor resolution, low damage
threshold, bulky size and complicated experimental setup, preventing further
practical applications. We propose and experimentally demonstrate an approach
to generate VVBs with a single metasurface by locally tailoring phase and
transverse polarization distribution. This method features the spin-orbit
coupling and the superposition of the converted part with an additional phase
pickup and the residual part without a phase change. By maintaining the equal
components for the converted part and the residual part, the cylindrically
polarized vortex beams carrying orbital angular momentum are experimentally
demonstrated based on a single metasurface at subwavelength scale. The proposed
approach provides unprecedented freedom in engineering the properties of
optical waves with the high-efficiency light utilization and a minimal
footprint.


title: Minimization of B\"uchi Automata using Fair Simulation

abstract:
  We present an algorithm, which reduces the size of B\"uchi automata using
fair simulation. Its time complexity is $\mathcal{O}(|Q|^4 \cdot |\Delta|^2)$,
the space complexity is $\mathcal{O}(|Q| \cdot |\Delta|)$.
  Simulation is a common approach for minimizing $\omega$-automata such as
B\"uchi automata. Direct simulation, delayed simulation and fair simulation are
different types of simulation. As we will show, minimization based on direct or
delayed simulation is conceptually simple. Whereas the algorithm based on fair
simulation is more complex. However, fair simulation allows a stronger
minimization of the automaton.
  Further, we illustrate the theory behind the algorithm, cover optimizations
useful in practice, give experimental results and compare our technique to
other minimization strategies.


title: The quantum-to-classical transition: contraction of associative products

abstract:
  The quantum-to-classical transition is considered from the point of view of
contractions of associative algebras. Various methods and ideas to deal with
contractions of associative algebras are discussed that account for a large
family of examples. As an instance of them, the commutative algebra of
functions in phase space, corresponding to classical physical observables, is
obtained as a contraction of the Moyal star-product which characterizes the
quantum case. Contractions of associative algebras associated to Lie algebras
are discussed, in particular the Weyl-Heisenberg and $SU(2)$ groups are
considered.


title:
Flows in and around active region NOAA12118 observed with the GREGOR
  solar telescope and SDO/HMI

abstract:
  Accurate measurements of magnetic and velocity fields in and around solar
active regions are key to unlocking the mysteries of the formation and the
decay of sunspots. High spatial resolution image and spectral sequences with a
high cadence obtained with the GREGOR solar telescope give us an opportunity to
scrutinize 3-D flow fields with local correlation tracking and imaging
spectroscopy. We present GREGOR early science data acquired in 2014 July -
August with the GREGOR Fabry-P\'erot Interferometer and the Blue Imaging
Channel. Time-series of blue continuum (? 450.6 nm) images of the small active
region NOAA 12118 were restored with the speckle masking technique to derive
horizontal proper motions and to track the evolution of morphological changes.
In addition, high-resolution observations are discussed in the context of
synoptic data from the Solar Dynamics Observatory.


title: A classification scheme for chimera states

abstract:
  We present a universal characterization scheme for chimera states applicable
to both numerical and experimental data sets. The scheme is based on two
correlation measures that enable a meaningful definition of chimera states as
well as their classification into three categories: stationary, turbulent and
breathing. In addition, these categories can be further subdivided according to
the time-stationarity of these two measures. We demonstrate that this approach
both is consistent with previously recognized chimera states and enables us to
classify states as chimeras which have not been categorized as such before.
Furthermore, the scheme allows for a qualitative and quantitative comparison of
experimental chimeras with chimeras obtained through numerical simulations.


title:
Exciton dynamics in GaAs/(Al,Ga)As core-shell nanowires with shell
  quantum dots

abstract:
  We study the dynamics of excitons in GaAs/(Al,Ga)As core-shell nanowires by
continuous-wave and time-resolved photoluminescence and photoluminescence
excitation spectroscopy. Strong Al segregation in the shell of the nanowires
leads to the formation of Ga-rich inclusions acting as quantum dots. At 10 K,
intense light emission associated with these shell quantum dots is observed.
The average radiative lifetime of excitons confined in the shell quantum dots
is 1.7 ns. We show that excitons may tunnel toward adjacent shell quantum dots
and nonradiative point defects. We investigate the changes in the dynamics of
charge carriers in the shell with increasing temperature, with particular
emphasis on the transfer of carriers from the shell to the core of the
nanowires. We finally discuss the implications of carrier localization in the
(Al,Ga)As shell for fundamental studies and optoelectronic applications based
on core-shell III-As nanowires.


title:
If-Conversion Optimization using Neuro Evolution of Augmenting
  Topologies

abstract:
  Control-flow dependence is an intrinsic limiting factor for pro- gram
acceleration. With the availability of instruction-level par- allel
architectures, if-conversion optimization has, therefore, be- come pivotal for
extracting parallelism from serial programs. While many if-conversion
optimization heuristics have been proposed in the literature, most of them
consider rigid criteria regardless of the underlying hardware and input
programs. In this paper, we propose a novel if-conversion scheme that preforms
an efficient if-conversion transformation using a machine learning technique
(NEAT). This method enables if-conversion customization overall branches within
a program unlike the literature that considered in- dividual branches. Our
technique also provides flexibility required when compiling for heterogeneous
systems. The efficacy of our approach is shown by experiments and reported
results which il- lustrate that the programs can be accelerated on the same
archi- tecture and without modifying the original code. Our technique applies
for general purpose programming languages (e.g. C/C++) and is transparent for
the programmer. We implemented our tech- nique in LLVM 3.6.1 compilation
infrastructure and experimented on the kernels of SPEC-CPU2006 v1.1 benchmarks
suite running on a multicore system of Intel(R) Xeon(R) 3.50GHz processors. Our
findings show a performance gain up to 8.6% over the stan- dard optimized code
(LLVM -O2 with if-conversion included), in- dicating the need for If-conversion
compilation optimization that can adapt to the unique characteristics of every
individual branch.


title:
A Survey of the State of the Art in Data Mining and Integration Query
  Languages

abstract:
  The major aim of this survey is to identify the strengths and weaknesses of a
representative set of Data-Mining and Integration (DMI) query languages. We
describe a set of properties of DMI-related languages that we use for a
systematic evaluation of these languages. In addition, we introduce a scoring
system that we use to quantify our opinion on how well a DMI-related language
supports a property. The languages surveyed in this paper include: DMQL,
MineSQL, MSQL, M2MQL, dmFSQL, OLEDB for DM, MINE RULE, and Oracle Data Mining.
This survey may help researchers to propose a DMI language that is beyond the
state-of-the-art, or it may help practitioners to select an existing language
that fits well a purpose.


title: Probing clustering in excited alpha-conjugate buclei

abstract:
  The fragmentation of quasi-projectiles from the nuclear reaction
$^{40}$Ca+$^{12}$C at 25 MeV per nucleon bombarding energy was used to produce
$\alpha$-emission sources. From a careful selection of these sources provided
by a complete detection and from comparisons with models of sequential and
simultaneous decays, evidence in favor of $\alpha$-particle clustering from
excited $^{16}O$, $^{20}Ne$ and $^{24}Mg$ is reported.


title:
Optimization of Energy-Constrained Wireless Powered Communication
  Networks with Heterogeneous Nodes

abstract:
  In this paper, we study wireless networks where nodes have two energy
sources, namely a battery and radio frequency (RF) energy harvesting circuitry.
We formulate two optimization problems with different objective functions,
namely maximizing the sum throughput and maximizing the minimum throughput, for
enhanced fairness. Furthermore, we show the generality of the proposed system
model through characterizing the conditions under which the two formulated
optimization problems can be reduced to the corresponding problems of different
known wireless networks, namely, conventional wireless networks
(battery-powered) and wireless powered communications networks (WPCNs) with
only RF energy harvesting nodes. In addition, we introduce WPCNs with two types
of nodes, with and without RF energy harvesting capability, in which the nodes
without RF energy harvesting are utilized to enhance the sum throughput, even
beyond WPCNs with all energy harvesting nodes. We establish the convexity of
all formulated problems which opens room for efficient solution using standard
techniques. Our numerical results show that the two types of wireless networks,
namely WPCNs with only RF energy harvesting nodes and conventional wireless
networks, are considered, respectively, as lower and upper bounds on the
performance of the generalized problem setting in terms of the maximum sum
throughput and the maxmin throughput. Moreover, the results reveal new insights
and throughput-fairness trade-offs unique to our new problem setting.


title: Shrinking targets in parametrised families

abstract:
  We consider certain parametrised families of piecewise expanding maps on the
interval, and estimate and sometimes calculate the Hausdorff dimension of the
set of parameters for which the orbit of a fixed point has a certain shrinking
target property. This generalises several similar results for
$\beta$-transformations to more general non-linear families. The proofs are
based on a result by Schnellmann on typicality in parametrised families.


title: The Fock Space of Loopy Spin Networks for Quantum Gravity

abstract:
  In the context of the coarse-graining of loop quantum gravity, we introduce
loopy and tagged spin networks, which generalize the standard spin network
states to account explicitly for non-trivial curvature and torsion. Both
structures relax the closure constraints imposed at the spin network vertices.
While tagged spin networks merely carry an extra spin at every vertex encoding
the overall closure defect, loopy spin networks allow for an arbitrary number
of loops attached to each vertex. These little loops can be interpreted as
local excitations of the quantum gravitational field and we discuss the
statistics to endow them with. The resulting Fock space of loopy spin networks
realizes new truncation of loop quantum gravity, allowing to formulate its
graph-changing dynamics on a fixed background graph plus local degrees of
freedom attached to the graph nodes. This provides a framework for
re-introducing a non-trivial background quantum geometry around which we would
study the effective dynamics of perturbations. We study how to implement the
dynamics of topological BF theory in this framework. We realize the projection
on flat connections through holonomy constraints and we pay special attention
to their often overlooked non-trivial flat solutions defined by higher
derivatives of the $\delta$-distribution.


title: Backreaction Effects on Nonequilibrium Spectral Function

abstract:
  We show how to compute the spectral function for a scalar theory in two
different scenarios: one which disregards back-reaction i.e. the response of
the environment to the external particle, and the other one where back-reaction
is considered. The calculation was performed using the Kadanoff-Baym equation
through the Keldysh formalism. When back-reaction is neglected, the spectral
function is equal to the equilibrium one, which can be represented as a
Breit-Wigner distribution. When back-reaction is introduced we observed a
damping in the spectral function of the thermal bath. Such behavior modifies
the damping rate for particles created within the bath. This certainly implies
phenomenological consequences right after the Big-Bang, when the primordial
bath was created.