title:
Scaling behavior of temperature-dependent thermopower in CeAu2Si2 under
  pressure

abstract:
  We report a combined study of in-plane resistivity and thermopower of the
pressure-induced heavy fermion superconductor CeAu2Si2 up to 27.8 GPa. It is
found that thermopower follows a scaling behavior in T/T* almost up to the
magnetic critical pressure pc ~ 22 GPa. By comparing with resistivity results,
we show that the magnitude and characteristic temperature dependence of
thermopower in this pressure range are governed by the Kondo coupling and
crystal-field splitting, respectively. Below pc, the superconducting transition
is preceded by a large negative thermopower minimum, suggesting a close
relationship between the two phenomena. Furthermore, thermopower of a variety
of Ce-based Kondo-lattices with different crystal structures follows the same
scaling relation up to T/T* ~ 2.


title: The "Sprekend Nederland" project and its application to accent location

abstract:
  This paper describes the data collection effort that is part of the project
Sprekend Nederland (The Netherlands Talking), and discusses its potential use
in Automatic Accent Location. We define Automatic Accent Location as the task
to describe the accent of a speaker in terms of the location of the speaker and
its history. We discuss possible ways of describing accent location, the
consequence these have for the task of automatic accent location, and potential
evaluation metrics.


title:
What is controlling the fragmentation process in the Infrared Dark Cloud
  G14.225-0.506? Differet level of fragmentation in twin hubs

abstract:
  We present observations of the 1.3 mm continuum emission toward hub-N and
hub-S of the infrared dark cloud G14.225-0.506 carried out with the
Submillimeter Array, together with observations of the dust emission at 870 and
350 microns obtained with APEX and CSO telescopes. The large scale dust
emission of both hubs consists of a single peaked clump elongated in the
direction of the associated filament. At small scales, the SMA images reveal
that both hubs fragment into several dust condensations. The fragmentation
level was assessed under the same conditions and we found that hub-N presents 4
fragments while hub-S is more fragmented, with 13 fragments identified. We
studied the density structure by means of a simultaneous fit of the radial
intensity profile at 870 and 350 microns and the spectral energy distribution
adopting a Plummer-like function to describe the density structure. The
parameters inferred from the model are remarkably similar in both hubs,
suggesting that density structure could not be responsible in determining the
fragmentation level. We estimated several physical parameters such as the level
of turbulence and the magnetic field strength, and we found no significant
differences between these hubs. The Jeans analysis indicates that the observed
fragmentation is more consistent with thermal Jeans fragmentation compared with
a scenario that turbulent support is included. The lower fragmentation level
observed in hub-N could be explained in terms of stronger UV radiation effects
from a nearby HII region, evolutionary effects, and/or stronger magnetic fields
at small scales, a scenario that should be further investigated.


title:
Sharp thresholds for Ramsey properties of strictly balanced nearly
  bipartite graphs

abstract:
  For a given graph $F$ we consider the family of (finite) graphs $G$ with the
Ramsey property for $F$, that is the set of such graphs $G$ with the property
that every two-colouring of the edges of $G$ yields a monochromatic copy of
$F$. For $F$ being a triangle Friedgut, R\"odl, Ruci\'nski, and Tetali (2004)
established the sharp threshold for the Ramsey property in random graphs. We
obtained a simpler proof of this result which extends to a more general class
of graphs $F$ including all cycles.
  The proof is based on Friedgut's criteria (1999) for sharp thresholds, and on
the recently developed container method for independent sets in hypergraphs by
Saxton and Thomason, and Balogh, Morris and Samotij. The proof builds on some
recent work of Friedgut et al. who established a similar result for van der
Waerden's theorem.


title: Collective couplings: rectification and supertransmittance

abstract:
  We investigate heat transport between two thermal reservoirs that are coupled
via a large spin composed of N identical two level systems. One coupling
implements the dissipative Dicke super- radiance. The other coupling is locally
of the pure-dephasing type and requires to go beyond the standard weak-coupling
limit by employing a Bogoliubov mapping in the corresponding reservoir. After
the mapping, the large spin is coupled to a collective mode with the original
pure-dephasing interaction, but the collective mode is dissipatively coupled to
the residual oscillators. Treating the large spin and the collective mode as
the system, a standard master equation approach is now able to capture the
energy transfer between the two reservoirs. Assuming fast relaxation of the
collective mode, we derive a coarse-grained rate equation for the large spin
only and discuss how the original Dicke superradiance is affected by the
presence of the additional reservoir. Our main finding is a cooperatively
enhanced rectification effect due to the interplay of supertransmittant heat
currents (scaling quadratically with $N$) and the asymmetric coupling to both
reservoirs. For large $N$, the system can thus significantly amplify current
asymmetries under bias reversal, functioning as a heat diode. We also briefly
discuss the case when the couplings of the collective spin are locally
dissipative, showing that the heat-diode effect is still present.


title:
Probing the Dragonfish star-forming complex: the ionizing population of
  the young massive cluster Mercer 30

abstract:
  The Dragonfish Nebula has been recently claimed to be powered by a
superluminous but elusive OB association. Instead, systematic searches in
near-infrared photometric surveys have found many other cluster candidates on
this sky region. Among these, the first confirmed young massive cluster was
Mercer 30, where Wolf-Rayet stars were found. We perform a new characterization
of Mercer 30 with unprecedented accuracy, combining NICMOS/HST and VVV
photometric data with multi-epoch ISAAC/VLT H- and K-band spectra. Stellar
parameters for most of spectroscopically observed cluster members are found
through precise non-LTE atmosphere modeling with the CMFGEN code. Our
spectrophotometric study for this cluster yields a new, revised distance of d =
(12.4 +- 1.7) kpc and a total of Q = 6.70 x 10^50 Lyman ionizing photons. A
cluster age of (4.0 +- 0.8) Myr is found through isochrone fitting, and a total
mass of (1.6 +- 0.6) x 10^4 Msol is estimated thanks to our extensive knowledge
of the post-main-sequence population. As a consequence, membership of Mercer 30
to the Dragonfish star-forming complex is confirmed, allowing us to use this
cluster as a probe for the whole complex, which turns out to be extremely large
(400 pc across) and located at the outer edge of the Sagittarius-Carina spiral
arm (11 kpc from the Galactic Center). The Dragonfish complex hosts 19 young
clusters or cluster candidates (including Mercer 30 and a new candidate
presented in this work) and an estimated minimum of 9 field Wolf-Rayet stars.
The sum of all these contributions accounts for, at least, 73% of the
Dragonfish Nebula ionization and leaves little or no room for the alleged
superluminous OB association; alternative explanations are discussed.


title: Requirement verification in simulation-based automation testing

abstract:
  The emergence of the Industrial Internet results in an increasing number of
complicated temporal interdependencies between automation systems and the
processes to be controlled. There is a need for verification methods that scale
better than formal verification methods and which are more exact than testing.
Simulation-based runtime verification is proposed as such a method, and an
application of Metric temporal logic is presented as a contribution. The
practical scalability of the proposed approach is validated against a
production process designed by an industrial partner, resulting in the
discovery of requirement violations.


title: Binarized Neural Networks

abstract:
  We introduce a method to train Binarized Neural Networks (BNNs) - neural
networks with binary weights and activations at run-time and when computing the
parameters' gradient at train-time. We conduct two sets of experiments, each
based on a different framework, namely Torch7 and Theano, where we train BNNs
on MNIST, CIFAR-10 and SVHN, and achieve nearly state-of-the-art results.
During the forward pass, BNNs drastically reduce memory size and accesses, and
replace most arithmetic operations with bit-wise operations, which might lead
to a great increase in power-efficiency. Last but not least, we wrote a binary
matrix multiplication GPU kernel with which it is possible to run our MNIST BNN
7 times faster than with an unoptimized GPU kernel, without suffering any loss
in classification accuracy. The code for training and running our BNNs is
available.


title: Wikipedia Tools for Google Spreadsheets

abstract:
  In this paper, we introduce the Wikipedia Tools for Google Spreadsheets.
Google Spreadsheets is part of a free, Web-based software office suite offered
by Google within its Google Docs service. It allows users to create and edit
spreadsheets online, while collaborating with other users in realtime.
Wikipedia is a free-access, free-content Internet encyclopedia, whose content
and data is available, among other means, through an API. With the Wikipedia
Tools for Google Spreadsheets, we have created a toolkit that facilitates
working with Wikipedia data from within a spreadsheet context. We make these
tools available as open-source on GitHub
[https://github.com/tomayac/wikipedia-tools-for-google-spreadsheets], released
under the permissive Apache 2.0 license.


title:
Universal low energy physics in one-dimensional multicompnent Fermi
  gases with a strongly repulsive $\delta$-function interaction

abstract:
  It was shown [Chin. Phys. Lett. 28, 020503 (2011)] that at zero temperature
the ground state of the one-dimensional (1D) $w$-component Fermi gas coincides
with that of the spinless Bose gas in the limit $\omega\to \infty$. This
behaviour was experimentally evidenced through a quasi-1D tightly trapping
ultracold ${}^{173}$Yb atoms in the recent paper [Nature Physics 10, 198
(2014)]. However, understanding of low temperature behaviour of the Fermi gases
with a repulsive interaction acquires spin-charge separated conformal field
theories of an effective Tomonaga-Luttinger liquid and an antiferromagnetic
$SU(w)$ Heisenberg spin chain. Here we analytically derive universal
thermodynamics of 1D strongly repulsive fermionic gases with $SU(w)$ symmetry
via the Yang-Yang thermodynamic Bethe ansatz method. The analytical free energy
and magnetic properties of the systems at low temperatures in a weak magnetic
field are obtained through the Wiener-Hopf method. In particular, the free
energy essentially manifests the spin-charge separated conformal field theories
for the high symmetry systems with arbitrary repulsive interaction strength. We
also find that the sound velocity of the Fermi gases in the large $w$ limit
coincides with that for the spinless Bose gas, whereas the spin velocity
vanishes quickly as $w$ becomes large. This indicates a strong suppression of
the Fermi exclusion statistics by the commutativity feature among the
$w$-component fermions with different spin states in the Tomonaga-Luttinger
liquid phase. Moreover, the equations of state and critical behaviour of
physical quantities at finite temperatures are analytically derived in terms of
the polylogarithm functions in the quantum critical region.


title: A field of quantum upper triangular matrices

abstract:
  We show that the duals of Woronowicz's quantum SU(2)-groups converge, within
the operator algebraic setting, to the group of special upper triangular 2-by-2
matrices with positive diagonal.


title: Evaluating e-voting: theory and practice

abstract:
  In the Netherlands as well as many other countries, the use of electronic
voting solutions is a recurrent topic of discussion. While electronic voting
certainly has advantages over paper voting, there are also important risks
involved. This paper presents an analysis of benefits and risks of electronic
voting, and shows the relevance of these issues by means of three case studies
of real-world implementations. Additionally, techniques that may be employed to
improve upon many of the current systems are presented. We conclude that the
advantages of E-voting do not outweigh the disadvantages, as the resulting
reduced verifiability and transparency seem hard to overcome.


title:
Detection and imaging of microcracking in complex media using coda wave
  interferometry (CWI) under linear resonance conditions

abstract:
  This letter presents the development of ultrasonic coda wave interferometry
to locate and image microcracks created within consolidated granular media,
polymer concrete. Results show that microcracks can be detected through coda
waves when the polymer concrete is submitted to a linear resonance. In
addition, the multiple scattering revealed to be dependent on the plane in
which the resonance is excited. In that sense, Acoustic emission measurements
were performed under flexural resonances generated in (XY) and (XZ) planes to
verify the existence of a possible structural anisotropy related to
microcracks. Recorded acoustic signatures revealed important differences in the
frequency contents, depending on the considered plane, with a consequent wealth
on the involved mechanisms during the microcracks vibrations.


title:
Light-quark baryon spectroscopy within ANL-Osaka dynamical
  coupled-channels approach

abstract:
  Recent results on the study of light-quark baryons with the ANL-Osaka
dynamical coupled-channels (DCC) approach are presented, which contain the N*
and Delta* spectroscopy via the analysis of pi N and gamma N reactions and the
Lambda* and Sigma* spectroscopy via the analysis of K- p reactions. A recent
application of our DCC approach to neutrino-nucleon reactions in the resonance
region is also presented.


title: First order algebraic differential equations of genus zero

abstract:
  We utilise recent results about the transcendental solutions to Riccati
differential equations to provide a comprehensive description of the nature of
the transcendental solutions to algebraic first order differential equations of
genus zero.


title:
Transiting planets as a precision clock to constrain the time variation
  of the gravitational constant

abstract:
  Analysis of transit times in exoplanetary systems accurately provides an
instantaneous orbital period, $P(t)$, of their member planets. A long-term
monitoring of those transiting planetary systems puts limits on the variability
of $P(t)$, which are translated into the constraints on the time variation of
the gravitational constant $G$. We apply this analysis to $10$ transiting
systems observed by the Kepler spacecraft, and find that $\Delta G/G\lesssim
5\times10^{-6}$ for 2009-2013, or $\dot{G}/G \lesssim
10^{-6}\,\mathrm{yr}^{-1}$ if $\dot{G}$ is constant. While the derived limit is
weaker than those from other analyses, it is complementary to them and can be
improved by analyzing numerous transiting systems that are continuously
monitored.


title: Fast K-Means with Accurate Bounds

abstract:
  We propose a novel accelerated exact k-means algorithm, which performs better
than the current state-of-the-art low-dimensional algorithm in 18 of 22
experiments, running up to 3 times faster. We also propose a general
improvement of existing state-of-the-art accelerated exact k-means algorithms
through better estimates of the distance bounds used to reduce the number of
distance calculations, and get a speedup in 36 of 44 experiments, up to 1.8
times faster.
  We have conducted experiments with our own implementations of existing
methods to ensure homogeneous evaluation of performance, and we show that our
implementations perform as well or better than existing available
implementations. Finally, we propose simplified variants of standard approaches
and show that they are faster than their fully-fledged counterparts in 59 of 62
experiments.


title: A criterion for reflectiveness of normal extensions

abstract:
  We give a new sufficient condition for the normal extensions in an admissible
Galois structure to be reflective. We then show that this condition is indeed
fulfilled when X is the (protomodular) reflective subcategory of S-special
objects of a Barr-exact S-protomodular category C, where S is the class of
split epimorphic trivial extensions in C. Next to some concrete examples where
the criterion may be applied, we also study the adjunction between a Barr-exact
unital category and its abelian core, which we prove to be admissible.


title:
Dual nature of magnetic dopants and competing trends in topological
  insulators

abstract:
  Topological insulators interacting with magnetic impurities have been
reported to host several unconventional effects. These phenomena are described
within the framework of gapping Dirac quasiparticles due to broken
time-reversal symmetry. However, the overwhelming majority of studies
demonstrate the presence of a finite density of states near the Dirac point
even once Topological insulators become magnetic. Here, we map the response of
topological states to magnetic impurities at the atomic scale. We demonstrate
that magnetic order and gapless states can coexist. We show how this is the
result of the delicate balance between two opposite trends, i.e. gap opening
and emergence of a Dirac node impurity band, both induced by the magnetic
dopants. Our results evidence a more intricate and rich scenario with respect
to the once generally assumed, showing how different electronic and magnetic
states may be generated and controlled in this fascinating class of materials.


title: Energy Efficient Video Fusion with Heterogeneous CPU-FPGA Devices

abstract:
  This paper presents a complete video fusion system with hardware acceleration
and investigates the energy trade-offs between computing in the CPU or the FPGA
device. The video fusion application is based on the Dual-Tree Complex Wavelet
Transforms (DT-CWT). In this work the transforms are mapped to a hardware
accelerator using high-level synthesis tools for the FPGA and also vectorized
code for the single instruction multiple data (SIMD) engine available in the
CPU. The accelerated system reduces computation time and energy by a factor of
2. Moreover, the results show a key finding that the FPGA is not always the
best choice for acceleration, and the SIMD engine should be selected when the
wavelet decomposition reduces the frame size below a certain threshold. This
dependency on workload size means that an adaptive system that intelligently
selects between the SIMD engine and the FPGA achieves the most energy and
performance efficiency point.


title: Multi-view Kernel Completion

abstract:
  In this paper, we introduce the first method that (1) can complete kernel
matrices with completely missing rows and columns as opposed to individual
missing kernel values, (2) does not require any of the kernels to be complete a
priori, and (3) can tackle non-linear kernels. These aspects are necessary in
practical applications such as integrating legacy data sets, learning under
sensor failures and learning when measurements are costly for some of the
views. The proposed approach predicts missing rows by modelling both
within-view and between-view relationships among kernel values. We show, both
on simulated data and real world data, that the proposed method outperforms
existing techniques in the restricted settings where they are available, and
extends applicability to new settings.


title:
The OGLE-III planet detection efficiency from six years of microlensing
  observations (2003 to 2008)

abstract:
  We use six years (2003 to 2008) of Optical Gravitational Lensing Experiment
III microlensing observations to derive the survey detection efficiency for a
range of planetary masses and projected distances from the host star. We
perform an independent analysis of the microlensing light curves to extract the
event parameters and compute the planet detection probability given the data.
2433 light curves satisfy our quality selection criteria and are retained for
further processing. The aggregate of the detection probabilities over the range
explored yields the expected number of microlensing planet detections. We
employ a Galactic model to convert this distribution from dimensionless to
physical units, \alpha/au and M_E. The survey sensitivity to small planets is
highest in the range 1 to 4 au, shifting to slightly larger separations for
more massive ones.


title: BPS pion domain walls in the supersymmetric chiral Lagrangian

abstract:
  We construct exact solutions of BPS pion domain walls in the four-dimensional
$\mathcal{N}=1$ supersymmetric SU(N) chiral Lagrangian with pion masses
introduced via linear and quadratic superpotentials. The model admits N
discrete vacua in the center of SU(N) for the linear superpotential. In
addition to the latter, new vacua appear for the quadratic superpotential. We
find that the domain wall solutions of pions (Nambu-Goldstone bosons) that
interpolate between a pair of (pion) vacua preserve half of supersymmetry.
Contrary to our expectations, we have not been able to find domain walls
involving the quasi-Nambu-Goldstone bosons present in the theory, which in turn
has the consequence that not all vacua of the theory are connected by a BPS
domain wall solution.


title: On Boundary Damped Inhomogeneous Timoshenko Beams and Related Problems

abstract:
  We consider the model equations for the Timoshenko beam as a first order
system in the framework of evolutionary equations. The focus is on boundary
damping, which is implemented as a dynamic boundary condition. A change of
material laws allows to include a large class of cases of boundary damping. By
choosing a particular material law, it is shown that the first order approach
to Sturm-Liouville problems with boundary damping is also covered.


title:
A Semi-Automated Method for Object Segmentation in Infant's Egocentric
  Videos to Study Object Perception

abstract:
  Object segmentation in infant's egocentric videos is a fundamental step in
studying how children perceive objects in early stages of development. From the
computer vision perspective, object segmentation in such videos pose quite a
few challenges because the child's view is unfocused, often with large head
movements, effecting in sudden changes in the child's point of view which leads
to frequent change in object properties such as size, shape and illumination.
In this paper, we develop a semi-automated, domain specific, method to address
these concerns and facilitate the object annotation process for cognitive
scientists allowing them to select and monitor the object under segmentation.
The method starts with an annotation from the user of the desired object and
employs graph cut segmentation and optical flow computation to predict the
object mask for subsequent video frames automatically. To maintain accuracy, we
use domain specific heuristic rules to re-initialize the program with new user
input whenever object properties change dramatically. The evaluations
demonstrate the high speed and accuracy of the presented method for object
segmentation in voluminous egocentric videos. We apply the proposed method to
investigate potential patterns in object distribution in child's view at
progressive ages.


title: Data-Efficient Reinforcement Learning in Continuous-State POMDPs

abstract:
  We present a data-efficient reinforcement learning algorithm resistant to
observation noise. Our method extends the highly data-efficient PILCO algorithm
(Deisenroth & Rasmussen, 2011) into partially observed Markov decision
processes (POMDPs) by considering the filtering process during policy
evaluation. PILCO conducts policy search, evaluating each policy by first
predicting an analytic distribution of possible system trajectories. We
additionally predict trajectories w.r.t. a filtering process, achieving
significantly higher performance than combining a filter with a policy
optimised by the original (unfiltered) framework. Our test setup is the
cartpole swing-up task with sensor noise, which involves nonlinear dynamics and
requires nonlinear control.


title: Mean and variance of the LQG cost function

abstract:
  Linear Quadratic Gaussian (LQG) systems are well-understood and methods to
minimize the expected cost are readily available. Less is known about the
statistical properties of the resulting cost function. The contribution of this
paper is a set of analytic expressions for the mean and variance of the LQG
cost function. These expressions are derived using two different methods, one
using solutions to Lyapunov equations and the other using only matrix
exponentials. Both the discounted and the non-discounted cost function are
considered, as well as the finite-time and the infinite-time cost function. The
derived expressions are successfully applied to an example system to reduce the
probability of the cost exceeding a given threshold.


title: Curves homogeneous under analytic transformations

abstract:
  We call a subset $K$ of $\mathbb C$ \emph{biholomorphically homogeneous} if
for any two points $p,q\in K$ there exists a neighborhood $U$ of $p$ and a
biholomorphism $\psi:U\to \psi(U)\subset \mathbb C$ such that $\psi(p)=q$ and
$\psi(K\cap U)= K\cap \psi(U)$. We show that a biholomorphically homogeneous
smooth curve $\gamma\subset \mathbb C$ is necessarily real-analytic.
Furthermore we show that the same holds for the homogeneity with respect of a
wider class of groups $G$ of real-analytic transformations of the plane. The
result also extends to subsets $K\subset \mathbb R^2$ which are just locally
closed.


title: Moving mirrors and the fluctuation-dissipation theorem

abstract:
  We investigate the random motion of a mirror in (1 + 1)-dimensions that is
immersed in a thermal bath of massless scalar particles which are interacting
with the mirror through a boundary condition. Imposing the Dirichlet or the
Neumann boundary conditions on the moving mirror, we evaluate the mean
radiation reaction force on the mirror and the correlation function describing
the fluctuations in the force about the mean value. From the correlation
function thus obtained, we explicitly establish the fluctuation-dissipation
theorem governing the moving mirror. Using the fluctuation-dissipation theorem,
we compute the mean-squared displacement of the mirror at finite and zero
temperature. We clarify a few points concerning the various limiting behavior
of the mean-squared displacement of the mirror. While we recover the standard
result at finite temperature, we find that the mirror diffuses logarithmically
at zero temperature, confirming similar conclusions that have been arrived at
earlier in this context. We also comment on a subtlety concerning the
comparison between zero temperature limit of the finite temperature result and
the exact zero temperature result.


title:
Bounds on the Price of Anarchy for a More General Class of Directed
  Graphs in Opinion Formation Games

abstract:
  In opinion formation games with directed graphs, a bounded price of anarchy
is only known for weighted Eulerian graphs. Thus, we bound the price of anarchy
for a more general class of directed graphs with conditions intuitively meaning
that each node does not influence the others more than she is influenced, where
the bounds depend on such difference (in a ratio). We also show that there
exists an example just slightly violating the conditions with an unbounded
price of anarchy.


title: Nanomagnetic logic with non-uniform states of clocking

abstract:
  Nanomagnetic logic transmits information along a path of nanomagnets. The
basic mechanism to drive such a transmission, known as clocking, can be
achieved by exploiting the spin-Hall effect, as recently observed in
experiments on Ta/CoFeB/MgO multilayers [D. Bhowmik, et al., Nat. Nano. 9, 59
(2013)]. This paper shows the fundamental mechanism of the spin-Hall driven
clocking by using a full micromagnetic framework and considering two different
devices, Ta/CoFeB/MgO and Pt/CoFeB/MgO. The former is used for a direct
comparison of the numerical results with the experiments while the latter
permits to predict the effect of the Dzyaloshinskii-Moriya interaction (DMI) in
the clocking mechanism. Results show that the clocking state is non-uniform and
it is characterized by the presence of domains separated by Bloch (N\'eel)
domain walls depending on the absence (presence) of the DMI. Our findings point
out that for the design of nanomagnetic logic a full micromagnetic approach is
necessary.


title:
Metallicity gradients in Local Universe galaxies: time evolution and
  effects of radial migration

abstract:
  Our knowledge of the shape of radial metallicity gradients in disc galaxies
has recently improved. Conversely, the understanding of their time evolution is
more complex, since it requires analysis of stellar populations with different
ages, or systematic studies of galaxies at different redshifts. In the Local
Universe, Hii regions and planetary nebulae (PNe) are important tools to
investigate it. We present an in-depth study of all nearby spiral galaxies
(M33, M31, NGC300, and M81) with direct-method nebular abundances of both
populations. For the first time, we also evaluate the radial migration of PN
populations. We analyse Hii region and PN properties to: determine whether
oxygen in PNe is a reliable tracer for past interstellar medium (ISM)
composition; homogenise the published datasets; estimate the migration of the
oldest stellar populations; determine the overall chemical enrichment and slope
evolution. We confirm that oxygen in PNe is a reliable tracer for the past ISM
metallicity. We find that PN gradients are flatter than or equal to those of
Hii regions. When radial motions are negligible, this result provides a direct
measurement of the time evolution of the gradient. For galaxies with dominant
radial motions, we provide upper limits on the gradient evolution. Finally, the
total metal content increases with time in all target galaxies, with early
morphological type having a larger increment Delta(O/H) than late-type
galaxies. Our findings provide important constraints to discriminate among
different galactic evolutionary scenarios, favouring cosmological models with
enhanced feedback from supernovae. The advent of extremely large telescopes
will allow us to include galaxies in a wider range of morphologies and
environments, thus putting firmer constraints to galaxy formation and evolution
scenarios.


title:
Effects of cluster size and spatial laser intensity distribution on
  fusion neutron generation by laser driven Deuterium clusters

abstract:
  A three dimensional molecular dynamic code is used to study the generation of
fusion neutrons from Coulomb explosion of Deuterium clusters driven by intense
near infra-red (NIR) laser ($\lambda=800nm$) of femtosecond pulse duration
($\tau=50 fs$) under beam-target interaction scheme. We have considered various
clusters of average sizes ($\langle R_0\rangle$=80,140,200\AA) which are
irradiated by a laser of peak spatial-temporal intensity of 1$\times10^{18}
W/cm^{2}$. The effects of cluster size and spatial laser intensity distribution
on ion energies due to the Coulomb explosion of the cluster are included by
convolution of single cluster single intensity ion energy distribution function
(IEDF) over a range of cluster sizes and laser intensities. The final
convoluted IEDF gets broadened on both lower and higher energy sides due to
this procedure. Furthermore, the neutron yield which takes into account the
convoluted IEDF, also gets modified by a factor of $\sim$2 compared to the case
when convolution effects are ignored.


title: Semidefinite bounds for nonbinary codes based on quadruples

abstract:
  For nonnegative integers $q,n,d$, let $A_q(n,d)$ denote the maximum
cardinality of a code of length $n$ over an alphabet $[q]$ with $q$ letters and
with minimum distance at least $d$. We consider the following upper bound on
$A_q(n,d)$. For any $k$, let $\CC_k$ be the collection of codes of cardinality
at most $k$. Then $A_q(n,d)$ is at most the maximum value of
$\sum_{v\in[q]^n}x(\{v\})$, where $x$ is a function $\CC_4\to R_+$ such that
$x(\emptyset)=1$ and $x(C)=0$ if $C$ has minimum distance less than $d$, and
such that the $\CC_2\times\CC_2$ matrix $(x(C\cup C'))_{C,C'\in\CC_2}$ is
positive semidefinite. By the symmetry of the problem, we can apply
representation theory to reduce the problem to a semidefinite programming
problem with order bounded by a polynomial in $n$. It yields the new upper
bounds $A_4(6,3)\leq 176$, $A_4(7,4)\leq 155$, $A_5(7,4)\leq 489$, and
$A_5(7,5)\leq 87$.


title:
Polarization observables in the $e^+ e^- \rightarrow \bar{\Lambda}
  \Lambda$ reaction

abstract:
  Cross-section, vector-polarization, and tensor-polarization distributions are
calculated for the reactions $e^+ e^- \rightarrow \bar{p}p$ and $e^+ e^-
\rightarrow \bar{\Lambda} \Lambda$. Each reaction requires six characteristic
functions that are bilinear in the, possibly complex, electromagnetic form
factors, denoted $G_E(P^2)$ and $G_M(P^2)$, of $p$ and $\Lambda$. For the
hyperon reaction also the joint-decay distributions of $\Lambda$ and
$\bar{\Lambda}$ are calculated. Their knowledge allow a complete determination
of the hyperon electromagnetic form factors, without measuring hyperon spins.
We explain how this is done in practice. For some tensor-polarization
components our results are in conflict with previously repeatedly published
distributions.


title: The white dwarf population within 40 pc of the Sun

abstract:
  The white dwarf luminosity function is an important tool to understand the
properties of the Solar neighborhood, like its star formation history, and its
age. Here we present a population synthesis study of the white dwarf population
within 40~pc from the Sun, and compare the results of this study with the
properties of the observed sample. We use a state-of-the-art population
synthesis code based on Monte Carlo techniques, that incorporates the most
recent and reliable white dwarf cooling sequences, an accurate description of
the Galactic neighborhood, and a realistic treatment of all the known
observational biases and selection procedures. We find a good agreement between
our theoretical models and the observed data. In particular, our simulations
reproduce a previously unexplained feature of the bright branch of the white
dwarf luminosity function, which we argue is due to a recent episode of star
formation. We also derive the age of the Solar neighborhood employing the
position of the observed cut-off of the white dwarf luminosity function,
obtaining ~8.9+-0.2 Gyr. We conclude that a detailed description of the
ensemble properties of the population of white dwarfs within 40pc of the Sun
allows us to obtain interesting constraints on the history of the Solar
neighborhood.


title:
High-Resolution Imaging of Water Maser Emission in the active galaxies
  NGC 6240 and M51

abstract:
  We present the results of observations of 22GHz H2O maser emission in NGC
6240 and M51 made with the Karl G. Jansky Very Large Array. Two major H2O maser
features and several minor features are detected toward the southern nucleus of
NGC 6240. These features are redshifted by about 300 km/s from the galaxy's
systemic velocity and remain unresolved at the synthesized beam size. A
combination of our two-epoch observations and published data reveals an
apparent correlation between the strength of the maser and the 22GHz radio
continuum emission, implying that the maser excitation relates to the activity
of an active galactic nucleus in the southern nucleus rather than star-forming
activity. The star-forming galaxy M51 hosts H2O maser emission in the center of
the galaxy; however, the origin of the maser has been an open question. We
report the first detection of 22GHz nuclear radio continuum emission in M51.
The continuum emission is co-located with the maser position, which indicates
that the maser arises from active galactic nucleus-activity and not from
star-forming activity in the galaxy.


title:
The mosaic multiple stellar populations in $\omega$ Centauri : the
  Horizontal Branch and the Main Sequence

abstract:
  We interpret the stellar population of $\omega$ Centauri by means of a
population synthesis analysis, following the most recent observational
guidelines for input metallicities, helium and [(C+N+O)/Fe] contents. We deal
at the same time with the main sequences, sub-giant and horizontal branch data.
The reproduction of the observed colour magnitude features is very satisfying
and bears interesting hints concerning the evolutionary history of this
peculiar stellar ensemble. Our main results are: 1) no significant spread in
age is required to fit the colour-magnitude diagram. Indeed we can use coeval
isochrones for the synthetic populations, and we estimate that the ages fall
within a $\sim 0.5$ Gyr time interval; in particular the most metal rich
population can be coeval (in the above meaning) with the others, if its stars
are very helium--rich (Y$\sim$0.37) and with the observed CNO enhancement
([(C+N+O)/Fe] = + 0.7); 2) a satisfactory fit of the whole HB is obtained,
consistent with the choice of the populations providing a good reproduction of
the main sequence and sub giant data. 3) the split in magnitude observed in the
red HB is well reproduced assuming the presence of two stellar populations in
the two different sequences observed: a metal poor population made of stars
evolving from the blue side (luminous branch) and a metal richer one whose
stars are in a stage closer to the zero age HB (dimmer branch). This
modelization also fits satisfactorily the period and the [Fe/H] distribution of
the RR Lyrae stars.


title: The isomorphic version of Brualdies nestedness is in P

abstract:
  The discrepancy BR for an $m \times n$ $0,1$-matrix from Brualdi and
Sanderson \cite{Brualdi1998} counts the minimum number of $1$'s which need to
be shifted in each row to the left to achieve its Ferrers matrix, i.e. each row
consists of consecutive $1$'s followed by consecutive $0$'s. For ecological
bipartite networks BR describes how nested a set of relationships is. Since
different labeled matrices can be isomorphic but possess different
discrepancies, we define a metric determining the minimum discrepancy in an
isomorphic class. We give a reduction to $k\leq n$ minimum weighted perfect
matching problems.


title:
Non-linear elastic effects in phase field crystal and amplitude
  equations: Comparison to ab initio simulations of bcc metals and graphene

abstract:
  We investigate non-linear elastic deformations in the phase field crystal
model and derived amplitude equations formulations. Two sources of
non-linearity are found, one of them based on geometric non-linearity expressed
through a finite strain tensor. It reflects the Eulerian structure of the
continuum models and correctly describes the strain dependence of the
stiffness. In general, the relevant strain tensor is related to the left
Cauchy-Green deformation tensor. In isotropic one- and two-dimensional
situations the elastic energy can be expressed equivalently through the right
deformation tensor. The predicted isotropic low temperature non-linear elastic
effects are directly related to the Birch-Murnaghan equation of state with bulk
modulus derivative $K'=4$ for bcc. A two-dimensional generalization suggests
$K'_{2D}=5$. These predictions are in agreement with ab initio results for
large strain bulk deformations of various bcc elements and graphene. Physical
non-linearity arises if the strain dependence of the density wave amplitudes is
taken into account and leads to elastic weakening. For anisotropic deformations
the magnitudes of the amplitudes depend on their relative orientation to the
applied strain.


title:
Structural, elastic, and electronic properties of newly discovered
  Li2PtSi3 superconductor: Effect of transition metals

abstract:
  First-principles calculations within the density functional theory (DFT) with
GGA-PBE exchange-correlation scheme have been employed to predict the
structural, the elastic and the electronic properties of newly discovered
lithium silicide superconductor, Li2PtSi3, for the first time. All the
theoretical results are compared with those calculated recently for
isostructural Li2IrSi3. The present study sheds light on the effect of
replacement of transition metal element Ir with Pt on different mechanical,
electronic, and superconducting properties. The effect of spin-orbit coupling
on electronic band structure was found to be insignificant for Li2PtSi3. The
difference in superconducting transition temperatures of Li2PtSi3 and Li2IrSi3
arises primarily due to the difference in electronic energy density of states
at the Fermi level. Somewhat reduced Debye temperature in Li2PtSi3 plays a
minor role. We have discussed the implications of the theoretical results in
details in this study.


title: Just Another Gibbs Additive Modeller: Interfacing JAGS and mgcv

abstract:
  The BUGS language offers a very flexible way of specifying complex
statistical models for the purposes of Gibbs sampling, while its JAGS variant
offers very convenient R integration via the rjags package. However, including
smoothers in JAGS models can involve some quite tedious coding, especially for
multivariate or adaptive smoothers. Further, if an additive smooth structure is
required then some care is needed, in order to centre smooths appropriately,
and to find appropriate starting values. R package mgcv implements a wide range
of smoothers, all in a manner appropriate for inclusion in JAGS code, and
automates centring and other smooth setup tasks. The purpose of this note is to
describe an interface between mgcv and JAGS, based around an R function,
`jagam', which takes a generalized additive model (GAM) as specified in mgcv
and automatically generates the JAGS model code and data required for inference
about the model via Gibbs sampling. Although the auto-generated JAGS code can
be run as is, the expectation is that the user would wish to modify it in order
to add complex stochastic model components readily specified in JAGS. A simple
interface is also provided for visualisation and further inference about the
estimated smooth components using standard mgcv functionality. The methods
described here will be un-necessarily inefficient if all that is required is
fully Bayesian inference about a standard GAM, rather than the full flexibility
of JAGS. In that case the BayesX package would be more efficient.


title: Variations on chaos in physics: from unpredictability to universal laws

abstract:
  The tremendous popular success of Chaos Theory shares some common points with
the not less fortunate Relativity: they both rely on a misunderstanding.
Indeed, ironically , the scientific meaning of these terms for mathematicians
and physicists is quite opposite to the one most people have in mind and are
attracted by. One may suspect that part of the psychological roots of this
seductive appeal relies in the fact that with these ambiguous names, together
with some superficial clich{\'e}s or slogans immediately related to them ("the
butterfly effect" or "everything is relative"), some have the more or less
secret hope to find matter that would undermine two pillars of science, namely
its ability to predict and to bring out a universal objectivity. Here I propose
to focus on Chaos Theory and illustrate on several examples how, very much like
Relativity, it strengthens the position it seems to contend with at first
sight: the failure of predictability can be overcome and leads to precise,
stable and even more universal predictions.


title: On superspecial abelian varieties over finite fields

abstract:
  In this paper we establish a new lattice description for superspecial abelian
varieties over a finite field $\mathbb {F}_q$ of $q=p^a$ elements. Our
description depends on the parity of the exponent $a$ of $q$. When $q$ is an
odd power of the prime $p$, we give an explicit formula for the number of
superspecial abelian surfaces over $\mathbb F_q$.


title:
Dynamic Spatial Autoregressive Models with Autoregressive and
  Heteroskedastic Disturbances

abstract:
  We propose a new class of models specifically tailored for spatio-temporal
data analysis. To this end, we generalize the spatial autoregressive model with
autoregressive and heteroskedastic disturbances, i.e. SARAR(1,1), by exploiting
the recent advancements in Score Driven (SD) models typically used in time
series econometrics. In particular, we allow for time-varying spatial
autoregressive coefficients as well as time-varying regressor coefficients and
cross-sectional standard deviations. We report an extensive Monte Carlo
simulation study in order to investigate the finite sample properties of the
Maximum Likelihood estimator for the new class of models as well as its
flexibility in explaining several dynamic spatial dependence processes. The new
proposed class of models are found to be economically preferred by rational
investors through an application in portfolio optimization.


title: Homogeneity of Cluster Ensembles

abstract:
  The expectation and the mean of partitions generated by a cluster ensemble
are not unique in general. This issue poses challenges in statistical inference
and cluster stability. In this contribution, we state sufficient conditions for
uniqueness of expectation and mean. The proposed conditions show that a unique
mean is neither exceptional nor generic. To cope with this issue, we introduce
homogeneity as a measure of how likely is a unique mean for a sample of
partitions. We show that homogeneity is related to cluster stability. This
result points to a possible conflict between cluster stability and diversity in
consensus clustering. To assess homogeneity in a practical setting, we propose
an efficient way to compute a lower bound of homogeneity. Empirical results
using the k-means algorithm suggest that uniqueness of the mean partition is
not exceptional for real-world data. Moreover, for samples of high homogeneity,
uniqueness can be enforced by increasing the number of data points or by
removing outlier partitions. In a broader context, this contribution can be
placed as a further step towards a statistical theory of partitions.


title: Applications of the divergence theorem in Bayesian inference and MaxEnt

abstract:
  Given a probability density $P({\bf x}|{\boldsymbol \lambda})$, where $\bf x$
represents continuous degrees of freedom and $\lambda$ a set of parameters, it
is possible to construct a general identity relating expectations of observable
quantities, which is a generalization of the equipartition theorem in
Thermodynamics.
  In this work we explore some of the consequences of this relation, both in
the context of sampling distributions and Bayesian posteriors, and how it can
be used to extract some information without the need for explicit calculation
of the partition function (or the Bayesian evidence, in the case of posterior
expectations). Together with the general family of fluctuation theorems it
constitutes a powerful tool for Bayesian/MaxEnt problems.


title:
Level 2 large deviation functionals for systems with and without
  detailed balance

abstract:
  Large deviation functions are an essential tool in the statistics of rare
events. Often they can be obtained by contraction from a so-called level 2
large deviation {\em functional} characterizing the empirical density of the
underlying stochastic process. For Langevin systems obeying detailed balance,
the explicit form of this functional has been known ever since the mathematical
work of Donsker and Varadhan. We rederive the Donsker-Varadhan result by using
stochastic path-integrals and then generalize it to situations without detailed
balance including non-equilibrium steady states. The proper incorporation of
the empirical probability flux turns out to be crucial. We elucidate the
relation between the large deviation functional and different notions of
entropy production in stochastic thermodynamics and discuss some aspects of the
ensuing contractions. Finally, we illustrate our findings with examples.


title: Completion and extension of operators in Kre\u{\i}n spaces

abstract:
  A generalization of the well-known results of M.G. Kre\u{\i}n about the
description of selfadjoint contractive extension of a hermitian contraction is
obtained. This generalization concerns the situation, where the selfadjoint
operator $A$ and extensions $\widetilde A$ belong to a Kre\u{\i}n space or a
Pontryagin space and their defect operators are allowed to have a fixed number
of negative eigenvalues. Also a result of Yu.L. Shmul'yan on completions of
nonnegative block operators is generalized for block operators with a fixed
number of negative eigenvalues in a Kre\u{\i}n space.
  This paper is a natural continuation of S. Hassi's and author's paper [5].


title: Local density approximation in site-occupation embedding theory

abstract:
  Site-occupation embedding theory (SOET) is a density-functional theory
(DFT)-based method which aims at modelling strongly correlated electrons. It is
in principle exact and applicable to model and quantum chemical Hamiltonians.
The theory is presented here for the Hubbard Hamiltonian. In contrast to
conventional DFT approaches, the site (or orbital) occupations are deduced in
SOET from a partially-interacting system consisting of one (or more) impurity
site(s) and non-interacting bath sites. The correlation energy of the bath is
then treated implicitly by means of a site-occupation functional. In this work,
we propose a simple impurity-occupation functional approximation based on the
two-level (2L) Hubbard model which is referred to as two-level impurity local
density approximation (2L-ILDA). Results obtained on a prototypical uniform
8-site Hubbard ring are promising. The extension of the method to larger
systems and more sophisticated model Hamiltonians is currently in progress.


title:
A nonlinear system with weak dissipation under external force on
  incommensurate frequency: coexistence of attractors

abstract:
  The behaviour of the 2D model system - the Ikeda map - is investigated in the
weakly dissipative regime under external forcing on the incommensurate
frequency. Coexistence of a large number of stable invariant curves is shown.
Dependence of the number of coexisting attractors on the external forcing
amplitude and nonlinearity parameter is investigated.


title:
Extension of the energy range of the experimental activation
  cross-sections data of longer-lived products of proton induced nuclear
  reactions on dysprosium up to 65 MeV

abstract:
  Activation cross-sections data of longer-lived products of proton induced
nuclear reactions on dysprosium were extended up to 65 MeV by using stacked
foil irradiation and gamma spectrometry experimental methods. Experimental
cross-sections data for the formation of the radionuclides $^{159}$Dy,
$^{157}$Dy, $^{155}$Dy, $^{161}$Tb, $^{160}$Tb, $^{156}$Tb, $^{155}$Tb,
$^{154m2}$Tb, $^{154m1}$Tb, $^{154g}$Tb, $^{153}$Tb, $^{152}$Tb and $^{151}$Tb
are reported in the 36-65 MeV energy range, and compared with an old dataset
from 1964. The experimental data were also compared with the results of cross
section calculations of the ALICE and EMPIRE nuclear model codes and of the
TALYS nuclear reaction model code as listed in the latest on-line libraries
TENDL 2013.


title: Generalized chord diagram expansions of Dyson-Schwinger equations

abstract:
  Series solutions for a large family of single equation Dyson-Schwinger
equations are given as expansions over decorated rooted connected chord
diagrams. The analytic input to the new expansions are the expansions of the
regularized integrals for the primitive graphs building the Dyson-Schwinger
equation. Each decorated chord diagram contributes a weighted monomial in the
coefficients of the expansions of the primitives and so indexes the analytic
solution in a tightly controlled way.


title: Dark Mode - Faraday Rotation Synergy for Enhanced Magneto-Optics

abstract:
  We examine the efficacy of Dark-mode plasmonics as a platform for enhanced
magneto-optics. Dark-mode of a small particle consists of two co-existing
equal-intensity and mutually opposing dipolar excitations. Each of these two
opposing dipoles may even resonate at or near the dark-mode frequency, but the
net dipole moment vanishes due to the mutual cancelation between the opposing
dipoles. We show that application of external magnetic bias may alleviate the
intense destructive interference. Furthermore, under external magnetic bias the
opposing dark-resonances of a plasmonic particle shift in opposite directions
and create a region of extremely sensitive Faraday rotation. We show that the
magnetized dark resonance in lossless Ag-like particle may provide more than 20
degrees rotation under magnetic fields of the order of 1-2 Tesla, exhibiting
magneto-plasmonic activity that is 2-3 orders of magnitude larger than that
observed in conventional plasmonic particle of the same material.


title: Diagnostics and future evolution analysis of the two parametric models

abstract:
  In this paper, we apply three diagnostics including $Om$, Statefinder
hierarchy and the growth rate of perturbations into discriminating the two
parametric models for the effective pressure with the $\Lambda$CDM model. By
using the $Om$ diagnostic, we find that both the model 1 and the model 2 can be
hardly distinguished from each other as well as the $\Lambda$CDM model in terms
of 68\% confidence level. As a supplement, by using the Statefinder hierarchy
diagnostics and the growth rate of perturbations, we discover that not only can
our two parametric models be well distinguished from $\Lambda$CDM model, but
also, by comparing with $Om$ diagnostic, the model 1 and the model 2 can be
distinguished better from each other. In addition, we also explore the fate of
universe evolution of our two models by means of the rip analysis.


title:
The role of helicity in triad interactions in 3D turbulence investigated
  in a new shell model

abstract:
  Fully developed homogeneous isotropic turbulence in 2D is fundamentally
different from 3D. In 2D, the simultaneous conservation of both energy and
enstrophy in the inertial ranges of scales leads to a forward cascade of
enstrophy and a reverse cascade of energy. In 3D, helicity, the integral of the
scalar product of velocity and vorticity, is also an inviscid flow invariant
along with kinetic energy. Unlike enstrophy, however, helicity does not block
the cascade of energy to small scales. Energy and helicity are not only
globally conserved but also conserved within each non-linear triadic
interaction between three plane waves in the spectral form of the
Navier--Stokes equation (NSE). By decomposing each plane wave into two helical
modes of opposite helicities each triadic interaction is split into a set of
eight triadic interactions between helical modes (Waleffe 1992). Biferale et
al. (2012) recently found that a subset of these interactions which render both
signs of helicity separately conserved (i.e. enstrophy-like) leads to an
inverse cascade of (part of) the energy. Motivated by this finding we introduce
a new shell model obtained from the NSE expressed in the helical basis (Waleffe
1992). By analysing and integrating the new model we attempt to explain why the
dual forward cascade of energy and helicity dominates in 3D turbulence.


title:
Sharp nonlinear stability criterion of viscous non-resistive MHD
  internal waves in 3D

abstract:
  We consider the dynamics of two layers of incompressible electrically
conducting fluid interacting with the magnetic field, which are confined within
a 3D horizontally infinite slab and separated by a free internal interface. We
assume that the upper fluid is heavier than the lower fluid so that the fluids
are susceptible to the Rayleigh-Taylor instability. Yet, we show that the
viscous and non-resistive problem around the equilibrium is nonlinearly stable
provided that the strength of the vertical component of the steady magnetic
field, $|\bar B_3|$, is greater than the critical value, $\mathcal{M}_c$, which
we identify explicitly. We also prove that the problem is nonlinearly unstable
if $|\bar B_3|<\mathcal{M}_c$. Our results indicate that the non-horizontal
magnetic field has strong stabilizing effect on the Rayleigh-Taylor instability
but the horizontal one does not have in 3D.


title:
On Pastewka & Robbins' criterion for macroscopic adhesion of rough
  surfaces

abstract:
  Pastewka & Robbins (PNAS, 111(9), 3298-3303, 2014) recently have proposed a
criterion to distinguish when two surfaces will stick together or not, and
suggested it shows a large conflict with asperity theories. It is found that
their criterion corresponds very closely to the Fuller and Tabor asperity model
one when bandwidth {\alpha} is small, but otherwise involves a rms ampliture of
roughness reduced by a factor Sqrt({\alpha}). Therefore, it implies the
stickiness of any rough surface is the same as that of the surface where
practically all wavelength components of roughness are removed except the very
fine ones, which is perhaps counterintuitive. The results are therefore very
interesting, if confirmed. Possible sources of approximations are indicated,
and a significant error is found in plotting the pull-off data which may
improve the fit with Fuller and Tabor. However, still they show finite pull-off
values in cases where both their own criterion and an asperity based one seem
to suggest non stickiness, and the results are in these respects inconclusive.


title: Geometry of compact complex manifolds with maximal torus action

abstract:
  In this present paper we study geometry of compact complex manifolds equipped
with a \emph{maximal} torus $T=(S^1)^k$ action. We give two equivalent
constructions providing examples of such manifolds given a simplicial fan
$\Sigma$ and a compelx subgroup $H\subset T_\mathbb C=(\mathbb C^*)^k$. On
every manifold $M$ we define the canonical holomorphic foliation $\mathcal F$
and under additional restrictions construct transverse-K\"{a}hler form
$\omega_\mathcal F$. As an application of these constructions, we prove some
results on geometry of manifolds~$M$ regarding its analytic subsets.


title:
Observation of normal-force-independent superlubricity in mesoscopic
  graphite contacts

abstract:
  We investigate the dependence of friction forces on normal load in
incommensurate micrometer size contacts between atomically smooth
single-crystal graphite surfaces under ambient conditions. Our experimental
results show that these contacts exhibit superlubricity (super-low friction),
which is robust against the application of normal load. The measured friction
coefficients are essentially zero and independent of the external normal load
up to a pressure of 1.67 MPa. The observation of load-independent
superlubricity in micro-scale contacts is a promising result for numerous
practical applications.


title: On projectional skeletons in Va\v{s}\'ak spaces

abstract:
  We provide an alternative proof of the theorem saying that any Va\v{s}\'ak
(or, weakly countably determined) Banach space admits a full $1$-projectional
skeleton. The proof is done with the use of the method of elementary submodels
and is comparably simple as the proof given by W.~Kubi\'s (2009) in case of
weakly compactly generated spaces.


title: Spectral analysis of SMC X-2 during its 2015 outburst

abstract:
  We report on the results of Swift and XMM-Newton observations of SMC X-2
during its last outburst in 2015 October, the first one since 2000. The source
reached a very high luminosity ($L \sim 10^{38}$ erg s$^{-1}$), which allowed
us to perform a detailed analysis of its timing and spectral properties. We
obtained a pulse period $P_{\rm spin}$ = 2.372267(5) s and a characterization
of the pulse profile also at low energies. The main spectral component is a
hard ($\Gamma \simeq 0$) power-law model with an exponential cut-off, but at
low energies we detected also a soft (with kT $\simeq$ 0.15 keV) thermal
component. Several emission lines can be observed at various energies. The
identification of these features with the transition lines of highly ionized N,
O, Ne, Si, and Fe suggests the presence of photoionized matter around the
accreting source.


title:
Invariant Gaussian fields on homogeneous spaces: explicit constructions
  and mean nodal volume

abstract:
  We review and study some of the properties of smooth Gaussian random fields
defined on a homogeneous space, under the assumption that the probability
distribution is invariant under the isometry group of the space. We first give
an exposition, building on early results of Yaglom, of the way in which
representation theory and the associated special functions make it possible to
give completely explicit descriptions of these fields in many cases of
interest. We then turn to the expected size of the zero-set: extending
two-dimensional results from Optics and Neuroscience, we show that every
invariant field comes with a natural unit of volume (defined in terms of the
geometrical redundancies in the field) with respect to which the average size
of the zero-set is given by a universal constant depending only on the
dimension of the source and target spaces, and not on the precise symmetry
exhibited by the field.


title: Dirac Equation and Planck-Scale Quantities

abstract:
  This work investigates in which form quantities with Planck dimensions occur
already in the common quantum theory with local Lorentz symmetry. Since such
Planck quantities as Planck length or Planck mass involve the Planck constant
h, the velocity of light c and the Newton gravitational constant G, the
relativistic Dirac equation (h, c) in the Newtonian gravitational potential (G)
can be considered as a test theory. The evaluation of the break-off condition
of the power series of the radial energy eigenfunctions of a purely
gravitational atom leads to exact terms for the energy eigenvalues E for
various special cases of the quantum numbers N, k and n = N + |k|. It turns out
that a meaningful atom model, based solely on Newtonian gravitational forces,
can result if, inter alia, the test mass m in the gravitational field of the
mass M is selected to be smaller than the Planck mass.


title:
A Random Growth Model for Power Grids and Other Spatially Embedded
  Infrastructure Networks

abstract:
  We propose a model to create synthetic networks that may also serve as a
narrative of a certain kind of infrastructure network evolution. It consists of
an initialization phase with the network extending tree-like for minimum cost
and a growth phase with an attachment rule giving a trade-off between
cost-optimization and redundancy. Furthermore, we implement the feature of some
lines being split during the grid's evolution. We show that the resulting
degree distribution has an exponential tail and may show a maximum at degree
two, suitable to observations of real-world power grid networks. In particular,
the mean degree and the slope of the exponential decay can be controlled in
partial independence. To verify to which extent the degree distribution is
described by our analytic form, we conduct statistical tests, showing that the
hypothesis of an exponential tail is well-accepted for our model data.


title:
Interplay of localisation and competing interaction channels: cascade of
  quantum phase transitions

abstract:
  We investigate the interplay of localization, interactions and (pseudo)spin
degrees of freedom on quantum states of particles on the lattice. Our results
show that breaking the paradigm density-density interaction $U_0\gg$
(pseudo)spin-(pseudo)spin interaction $U_s$ will drive the sequence of quantum
phase transitions (QPT), where (pseudo)spin state and particle ordering, in
case of several particle species, on the lattice are strongly changed. QPT
driven by competing interactions, $|U_s|\sim U_0$, manifest itself in
singularities of effective exchange integrals. $|U_s|\sim U_0$ implies a
frustration when the interactions standing alone drive the system to different
phases. Even at $U_s=0$, there is typically a QPT induced by $U_s$ sign change.
Vector cold atoms, Fermions or Bosons, on optical lattices are the
state-of-the-art realization of our system where $U_s$ is tunable \textit{in
situ}.


title:
The ESO UVES Advanced Data Products Quasar Sample - VI. Sub-Damped
  Lyman-$\alpha$ Metallicity Measurements and the Circum-Galactic Medium

abstract:
  The Circum-Galactic Medium (CGM) can be probed through the analysis of
absorbing systems in the line-of-sight to bright background quasars. We present
measurements of the metallicity of a new sample of 15 sub-damped Lyman-$\alpha$
absorbers (sub-DLAs, defined as absorbers with 19.0 < log N(H I) < 20.3) with
redshift 0.584 < $\rm z_{abs}$ < 3.104 from the ESO Ultra-Violet Echelle
Spectrograph (UVES) Advanced Data Products Quasar Sample (EUADP). We combine
these results with other measurements from the literature to produce a
compilation of metallicity measurements for 92 sub-DLAs as well as a sample of
362 DLAs. We apply a multi-element analysis to quantify the amount of dust in
these two classes of systems. We find that either the element depletion
patterns in these systems differ from the Galactic depletion patterns or they
have a different nucleosynthetic history than our own Galaxy. We propose a new
method to derive the velocity width of absorption profiles, using the modeled
Voigt profile features. The correlation between the velocity width delta_V90 of
the absorption profile and the metallicity is found to be tighter for DLAs than
for sub-DLAs. We report hints of a bimodal distribution in the [Fe/H]
metallicity of low redshift (z < 1.25) sub-DLAs, which is unseen at higher
redshifts. This feature can be interpreted as a signature from the metal-poor,
accreting gas and the metal-rich, outflowing gas, both being traced by sub-DLAs
at low redshifts.


title: Third Group Cohomology and Gerbes over Lie Groups

abstract:
  The topological classification of gerbes, as principal bundles with the
structure group the projective unitary group of a complex Hilbert space, over a
topological space $H$ is given by the third cohomology $\text{H}^3(H, \Bbb Z)$.
When $H$ is a topological group the integral cohomology is often related to a
locally continuous (or in the case of a Lie group, locally smooth) third group
cohomology of $H$. We shall study in more detail this relation in the case of a
group extension $1\to N \to G \to H \to 1$ when the gerbe is defined by an
abelian extension $1\to A \to \hat N \to N \to 1$ of $N$. In particular, when
$\text{H}_s^1(N,A)$ vanishes we shall construct a transgression map
$\text{H}^2_s(N, A) \to \text{H}^3_s(H, A^N)$, where $A^N$ is the subgroup of
$N$-invariants in $A$ and the subscript $s$ denotes the locally smooth
cohomology. Examples of this relation appear in gauge theory which are
discussed in the paper.


title: On a Possible Stationary Point in High-Energy Scattering

abstract:
  We discuss a curious observation: at energies from the ISR and up to the LHC,
inclusively, the differential cross-section of elastic proton-proton scattering
remains almost energy-independent at the transferred momentum t =-0.21 GeV^2 at
the level of 7,5 mb/GeV^2.The latter value can be considered as a prediction
for dsigma/dt at 13 TeV. We also obtain a lower bound for the forward pp slope
at 13 GeV.


title: Minimal Extension of Einstein's Theory: The Quartic Gravity

abstract:
  We study structure of solutions of the recently constructed minimal
extensions of Einstein's gravity in four dimensions at the quartic curvature
level. The extended higher derivative theory, just like Einstein's gravity, has
only a massless spin-two graviton about its unique maximally symmetric vacuum.
The extended theory does not admit the Schwarzschild or Kerr metrics as exact
solutions, hence there is no issue of Schwarzschild type singularity but,
approximately, outside a source, spherically symmetric metric with the correct
Newtonian limit is recovered. We also show that for all Einstein space-times,
square of the Riemann tensor (the Kretschmann scalar or the Gauss-Bonnet
invariant) obeys a non-linear scalar Klein-Gordon equation.


title: Critical Phenomena in Non-spherically Symmetric Scalar Bubble Collapse

abstract:
  We investigate numerically the critical behaviour which occurs in the
collapse of both spherically symmetric and asymmetric scalar field bubbles with
full general relativity. We use a minimally coupled scalar field subject to a
"double well" interaction potential, with the bubble wall spanning the barrier
between two degenerate minima. We find that the spherically symmetric case
exhibits Type 2 critical behaviour with the critical index consistent with a
value of gamma = 0.37 as expected. In the asymmetric case, we find that again
our results are consistent with a value of gamma = 0.37 for the dominant
unstable mode. We do not see strong evidence of echoing in the solutions, which
could be due to the fact that the coordinates are not well adapted to the
echoing behaviour, or due to being still too far from the critical point to
properly observe the critical solution.


title: Pollinator foraging flexibility and coexistence of competing plants

abstract:
  We use the optimal foraging theory to study coexistence between two plant
species and a generalist pollinator. We compare conditions for plant
coexistence for non-adaptive vs. adaptive pollinators that adjust their
foraging strategy to maximize fitness. When pollinators have fixed preferences,
we show that plant coexistence typically requires both weak competition between
plants for resources (e.g., space or nutrients) and pollinator preferences that
are not too biased in favour of either plant. We also show how plant
coexistence is promoted by indirect facilitation via the pollinator. When
pollinators are adaptive foragers, pollinator's diet maximizes pollinator's
fitness measured as the per capita population growth rate. Simulations show
that this has two conflicting consequences for plant coexistence. On the one
hand, when competition between pollinators is weak, adaptation favours
pollinator specialization on the more profitable plant which increases
asymmetries in plant competition and makes their coexistence less likely. On
the other hand, when competition between pollinators is strong, adaptation
promotes generalism, which facilitates plant coexistence. In addition, adaptive
foraging allows pollinators to survive sudden loss of the preferred plant host,
thus preventing further collapse of the entire community.
  Keywords: mutualism, competition, optimal foraging, evolutionarily stable
strategy, coexistence, adaptation rate


title:
Higher-derivative Lorentz-breaking terms in extended QED at the finite
  temperature

abstract:
  In this paper we discuss finiteness and ambiguities of the higher-derivative
Lorentz-breaking terms in extended QED with a magnetic coupling at the finite
temperature. We find that, beside of the higher-derivative
Carroll-Field-Jackiw-like term and Myers-Pospelov term, many new terms arise in
a finite temperature case, but most of them vanish in high temperature limit.


title:
No clear evidence of ferroelectric order in tensile-strained
  anatase-TiO2 thin films grown on (110) NdGaO3 substrates

abstract:
  Very recently there was a report of the discovery using piezoelectric force
microscopy (PFM) of a switchable ferroelectric polarization in 1.6 % tensile
strained TiO2 thin film with anatase crystal structure (see N. Deepak et al.
Adv. Funct. Mater. 2014, 24, 2844). The polarization disappeared only above 450
K, which was assigned as a Curie temperature, Tc. Here we have performed X-ray
diffraction, second-harmonic generation (SHG) and infrared investigations of
the same films. Phonon frequencies exhibit less than a 10 % shift down with the
tensile strain and no anomaly near expected TC. SHG experiment did not reveal
any signal characteristic for inversion symmetry breaking, as expected in
ferroelectric phase, and the c-lattice parameter exhibits no anomaly on heating
near expected TC. Based on these results, we can summarize that we were not
able to confirm the previously discovered ferroelectricity in tensile-strained
anatase-TiO2 thin films.


title:
$\boldsymbol{L}_{\infty}$-approximation in Korobov spaces with
  Exponential Weights

abstract:
  We study multivariate $\boldsymbol{L}_{\infty}$-approximation for a weighted
Korobov space of periodic functions for which the Fourier coefficients decay
exponentially fast. The weights are defined, in particular, in terms of two
sequences $\boldsymbol{a}=\{a_j\}$ and $\boldsymbol{b}=\{b_j\}$ of positive
real numbers bounded away from zero. We study the minimal worst-case error
$e^{\boldsymbol{L}_{\infty}\mathrm{-app},\Lambda}(n,s)$ of all algorithms that
use $n$ information evaluations from a class $\Lambda$ in the $s$-variate case.
We consider two classes $\Lambda$ in this paper: the class $\Lambda^{{\rm
all}}$ of all linear functionals and the class $\Lambda^{{\rm std}}$ of only
function evaluations.
  We study exponential convergence of the minimal worst-case error, which means
that $e^{\boldsymbol{L}_{\infty}\mathrm{-app},\Lambda}(n,s)$ converges to zero
exponentially fast with increasing $n$. Furthermore, we consider how the error
depends on the dimension $s$. To this end, we define the notions of
$\kappa$-EC-weak, EC-polynomial and EC-strong polynomial tractability, where EC
stands for "exponential convergence". In particular, EC-polynomial tractability
means that we need a polynomial number of information evaluations in $s$ and
$1+\log\,\varepsilon^{-1}$ to compute an $\varepsilon$-approximation. We derive
necessary and sufficient conditions on the sequences $\boldsymbol{a}$ and
$\boldsymbol{b}$ for obtaining exponential error convergence, and also for
obtaining the various notions of tractability. The results are the same for
both classes $\Lambda$.


title: Finite domination and Novikov homology over strongly Z-graded rings

abstract:
  Let L be a strongly Z-graded ring, and let C be a bounded chain complex of
finitely generated L-modules. We give a homological characterisation of when C
is homotopy equivalent, over L_0, to a bounded complex of finitely generated
projective L_0-modules, generalising known results for twisted Laurent
polynomial rings.


title:
Characterization of a Multi-User Indoor Positioning System Based on Low
  Cost Depth Vision (Kinect) for Monitoring Human Activity in a Smart Home

abstract:
  An increasing number of systems use indoor positioning for many scenarios
such as asset tracking, health care, games, manufacturing, logistics, shopping,
and security. Many technologies are available and the use of depth cameras is
becoming more and more attractive as this kind of device becomes affordable and
easy to handle. This paper contributes to the effort of creating an indoor
positioning system based on low cost depth cameras (Kinect). A method is
proposed to optimize the calibration of the depth cameras, to describe the
multi-camera data fusion and to specify a global positioning projection to
maintain the compatibility with outdoor positioning systems.
  The monitoring of the people trajectories at home is intended for the early
detection of a shift in daily activities which highlights disabilities and loss
of autonomy. This system is meant to improve homecare health management at home
for a better end of life at a sustainable cost for the community.


title:
DECOrrelated feature space partitioning for distributed sparse
  regression

abstract:
  Fitting statistical models is computationally challenging when the sample
size or the dimension of the dataset is huge. An attractive approach for
down-scaling the problem size is to first partition the dataset into subsets
and then fit using distributed algorithms. The dataset can be partitioned
either horizontally (in the sample space) or vertically (in the feature space).
While the majority of the literature focuses on sample space partitioning,
feature space partitioning is more effective when $p\gg n$. Existing methods
for partitioning features, however, are either vulnerable to high correlations
or inefficient in reducing the model dimension. In this paper, we solve these
problems through a new embarrassingly parallel framework named DECO for
distributed variable selection and parameter estimation. In DECO, variables are
first partitioned and allocated to $m$ distributed workers. The decorrelated
subset data within each worker are then fitted via any algorithm designed for
high-dimensional problems. We show that by incorporating the decorrelation
step, DECO can achieve consistent variable selection and parameter estimation
on each subset with (almost) no assumptions. In addition, the convergence rate
is nearly minimax optimal for both sparse and weakly sparse models and does NOT
depend on the partition number $m$. Extensive numerical experiments are
provided to illustrate the performance of the new framework.


title:
Progress Towards the Conjecture on APN Functions and Absolutely
  Irreducible Polynomials

abstract:
  Almost Perfect Nonlinear (APN) functions are very useful in cryptography,
when they are used as S-Boxes, because of their good resistance to differential
cryptanalysis. An APN function $f:\mathbb{F}_{2^n}\rightarrow\mathbb{F}_{2^n}$
is called exceptional APN if it is APN on infinitely many extensions of
$\mathbb{F}_{2^n}$. Aubry, McGuire and Rodier conjectured that the only
exceptional APN functions are the Gold and the Kasami-Welch monomial functions.
They established that a polynomial function of odd degree is not exceptional
APN provided the degree is not a Gold number $(2^k+1)$ or a Kasami-Welch number
$(2^{2k}-2^k+1)$. When the degree of the polynomial function is a Gold number,
several partial results have been obtained [1, 7, 8, 10, 17]. One of the
results in this article is a proof of the relatively primeness of the
multivariate APN polynomial conjecture, in the Gold degree case. This helps us
extend substantially previous results. We prove that Gold degree polynomials of
the form $x^{2^k+1}+h(x)$, where $deg(h)$ is any odd integer (with the natural
exceptions), can not be exceptional APN.
  We also show absolute irreducibility of several classes of multivariate
polynomials over finite fields and discuss their applications.


title: Hexatonic Systems and Dual Groups in Mathematical Music Theory

abstract:
  Motivated by the music-theoretical work of Richard Cohn and David Clampitt on
late-nineteenth century harmony, we mathematically prove that the PL-group of a
hexatonic cycle is dual (in the sense of Lewin) to its T/I-stabilizer. Our
point of departure is Cohn's notions of maximal smoothness and hexatonic cycle,
and the symmetry group of the 12-gon; we do not make use of the duality between
the T/I-group and PLR-group. We also discuss how some ideas in the present
paper could be used in the proof of T/I-PLR duality by Crans--Fiore--Satyendra.


title:
Chiral Random Matrix Model at Finite Chemical Potential: Characteristic
  Determinant and Edge Universality

abstract:
  We derive an exact formula for the stochastic evolution of the characteristic
determinant of a class of deformed Wishart matrices following from a chiral
random matrix model of QCD at finite chemical potential. In the WKB
approximation, the characteristic determinant describes a sharp droplet of
eigenvalues that deforms and expands at large stochastic times. Beyond the WKB
limit, the edges of the droplet are fuzzy and described by universal edge
functions. At the chiral point, the characteristic determinant in the
microscopic limit is universal. Remarkably, the physical chiral condensate at
finite chemical potential may be extracted from current and quenched lattice
Dirac spectra using the universal edge scaling laws, without having to solve
the QCD sign problem.


title:
Nondestructive Probing of Means, Variances, and Correlations of
  Ultracold-Atomic-System Densities via Qubit Impurities

abstract:
  We show how impurity atoms can measure moments of ultracold atomic gas
densities, using the example of bosons in a one-dimensional lattice. This
builds on a body of work regarding the probing of systems by measuring the
dephasing of an immersed qubit. We show this dephasing is captured by a
function resembling characteristic functions of probability theory, of which
the derivatives at short times reveal moments of the system operator to which
the qubit couples. For a qubit formed by an impurity atom, in a system of
ultracold atoms, this operator can be the density of the system at the location
of the impurity, and thus, means, variances, and correlations of the atomic
densities are accessible.

categories: cond-mat.quant-gas cond-mat.mes-hall physics.atom-ph quant-ph


title:
Direct evidence of superconductivity and determination of the superfluid
  density in buried ultrathin FeSe grown on SrTiO$_3$

abstract:
  Bulk FeSe is superconducting with a critical temperature $T_c$ $\cong$ 8 K
and SrTiO$_3$ is insulating in nature, yet high-temperature superconductivity
has been reported at the interface between a single-layer FeSe and SrTiO$_3$.
Angle resolved photoemission spectroscopy and scanning tunneling microscopy
measurements observe a gap opening at the Fermi surface below $\approx$ 60 K.
Elucidating the microscopic properties and understanding the pairing mechanism
of single-layer FeSe is of utmost importance as it is a basic building block of
iron-based superconductors. Here, we use the low-energy muon spin
rotation/relaxation technique (LE-$\mu$SR) to detect and quantify the
supercarrier density and determine the gap symmetry in FeSe grown on SrTiO$_3$
(100). Measurements in applied field show a temperature dependent broadening of
the field distribution below $\sim$ 60 K, reflecting the superconducting
transition and formation of a vortex state. Zero field measurements rule out
the presence of magnetism of static or fluctuating origin. From the
inhomogeneous field distribution, we determine an effective sheet supercarrier
density $n_s^{2D} \simeq 6 \times 10^{14}$ cm$^{-2}$ at $T \rightarrow 0$ K,
which is a factor of 4 larger than expected from ARPES measurements of the
excess electron count per Fe of 1 monolayer (ML) FeSe. The temperature
dependence of the superfluid density $n_s(T)$ can be well described down to
$\sim$ 10 K by simple s-wave BCS, indicating a rather clean superconducting
phase with a gap of 10.2(1.1) meV. The result is a clear indication of the
gradual formation of a two dimensional vortex lattice existing over the entire
large FeSe/STO interface and provides unambiguous evidence for robust
superconductivity below 60 K in ultrathin FeSe.


title: Absolute Measurement of Quantum-Limited Interferometric Displacements

abstract:
  A methodology is introduced that enables an absolute, quantum-limited
measurement of sub-wavelength interferometric displacements. The technique
utilizes a high-frequency optical path modulation within an interferometer
operated in a homodyne configuration. All of the information necessary to fully
characterize the resultant path displacement is contained within the relative
strengths of the various harmonics of the phase modulation. The method, which
is straightforward and readily implementable, allows a direct measurement of
the theoretical Cram\'er-Rao limit of detection without any assumptions on the
nature of the light source.


title:
Complete Action for Open Superstring Field Theory with Cyclic $A_\infty$
  Structure

abstract:
  We construct a gauge invariant action for the Neveu-Schwarz and Ramond
sectors of open superstring field theory realizing a cyclic $A_\infty$
structure, providing the first complete and fully explicit solution to the
classical Batalin-Vilkovisky master equation in superstring field theory. We
also demonstrate the equivalence of our action to the Wess-Zumino-Witten-based
construction of Kunitomo and one of the authors.


title: Open Superstring Field Theory on the Restricted Hilbert Space

abstract:
  Recently an action for open superstring field theory was proposed where the
Neveu-Schwarz sector is formulated in the large Hilbert space while the Ramond
sector lives in a restriction of the small Hilbert space. The purpose of this
note is to clarify the relation of the restricted Hilbert space with other
approaches and to formulate open superstring field theory entirely in the small
Hilbert space.


title: $C_{n}$-moves and the difference of Jones polynomials for links

abstract:
  The Jones polynomial $V_{L}(t)$ for an oriented link $L$ is a one-variable
Laurent polynomial link invariant discovered by Jones. For any integer $n\ge
3$, we show that: (1) the difference of Jones polynomials for two oriented
links which are $C_{n}$-equivalent is divisible by
$\left(t-1\right)^{n}\left(t^{2}+t+1\right)\left(t^{2}+1\right)$, and (2) there
exists a pair of two oriented knots which are $C_{n}$-equivalent such that the
difference of the Jones polynomials for them equals
$\left(t-1\right)^{n}\left(t^{2}+t+1\right)\left(t^{2}+1\right)$.


title:
Protoplanetary disk shadowing by gas infalling onto the young star AK
  Sco

abstract:
  Young solar-type stars grow through the accretion of material from the
circumstellar disk during pre-main sequence (PMS) evolution. The ultraviolet
radiation generated in this process plays a key role in the chemistry and
evolution of young planetary disks. In particular, the hydrogen Lyman-alpha
line (Lya) etches the disk surface by driving photoevaporative flows that
control disk evolution. Using the Hubble Space Telescope, we have monitored the
PMS binary star AK Sco during the periastron passage and have detected a drop
of the H2 flux by up to 10% lasting 5.9 hours. We show that the decrease of the
H2 flux can be produced by the occultation of the stellar Lya photons by a gas
stream in free fall from 3 R*. Given the high optical depth of the Lya line, a
very low gas column of NH > 5e17 cm-2 suffices to block the Lya radiation
without producing noticeable effects in the rest of the stellar spectral
tracers.


title:
Tumour ROI Estimation in Ultrasound Images via Radon Barcodes in
  Patients with Locally Advanced Breast Cancer

abstract:
  Quantitative ultrasound (QUS) methods provide a promising framework that can
non-invasively and inexpensively be used to predict or assess the tumour
response to cancer treatment. The first step in using the QUS methods is to
select a region of interest (ROI) inside the tumour in ultrasound images.
Manual segmentation, however, is very time consuming and tedious. In this
paper, a semi-automated approach will be proposed to roughly localize an ROI
for a tumour in ultrasound images of patients with locally advanced breast
cancer (LABC). Content-based barcodes, a recently introduced binary descriptor
based on Radon transform, were used in order to find similar cases and estimate
a bounding box surrounding the tumour. Experiments with 33 B-scan images
resulted in promising results with an accuracy of $81\%$.


title: On Super-Planckian thermal emission in far field regime

abstract:
  We study, in the framework of the Landauer theory, the thermal emission in
far-field regime, of arbitrary indefinite planar media and finite size systems.
We prove that the flux radiated by the former is bounded by the blackbody
emission while, for the second, there is in principle, no upper limit
demonstrating so the possibility for a super-Planckian thermal emission with
finite size systems.


title:
Local existence for the non-resistive MHD equations in nearly optimal
  Sobolev spaces

abstract:
  This paper establishes the local-in-time existence and uniqueness of
solutions to the viscous, non-resistive magnetohydrodynamics (MHD) equations in
$\mathbb{R}^d$, $d=2,3$, with initial data $B_0\in H^s(\mathbb{R}^d)$ and
$u_0\in H^{s-1+\varepsilon}(\mathbb{R}^d)$ for $s>d/2$ and any
$0<\varepsilon<1$. The proof relies on maximal regularity estimates for the
Stokes equation. The obstruction to taking $\varepsilon=0$ is explained by the
failure of solutions of the heat equation with initial data $u_0\in H^{s-1}$ to
satisfy $u\in L^1(0,T;H^{s+1})$; we provide an explicit example of this
phenomenon.


title: Edge Lower Bounds for List Critical Graphs, via Discharging

abstract:
  A graph $G$ is $k$-critical if $G$ is not $(k-1)$-colorable, but every proper
subgraph of $G$ is $(k-1)$-colorable. A graph $G$ is $k$-choosable if $G$ has
an $L$-coloring from every list assignment $L$ with $|L(v)|=k$ for all $v$, and
a graph $G$ is \emph{$k$-list-critical} if $G$ is not $(k-1)$-choosable, but
every proper subgraph of $G$ is $(k-1)$-choosable. The problem of bounding
(from below) the number of edges in a $k$-critical graph has been widely
studied, starting with work of Gallai and culminating with the seminal results
of Kostochka and Yancey, who essentially solved the problem. In this paper, we
improve the best lower bound on the number of edges in a $k$-list-critical
graph. Our proof uses the discharging method, which makes it simpler and more
modular than previous work in this area.


title:
Kershaw closures for linear transport equations in slab geometry II:
  high-order realizability-preserving discontinuous-Galerkin schemes

abstract:
  This paper provides a generalization of the realizability-preserving
discontinuous-Galerkin scheme for quadrature-based minimum-entropy models to
full-moment models of arbitrary order. It is applied to the class of Kershaw
closures, which are able to provide a cheap closure of the moment problem. This
results in an efficient algorithm for the underlying linear transport equation.
The efficiency of high-order methods is demonstrated using numerical
convergence tests and non-smooth benchmark problems.


title:
Inverse problems for $p$-Laplace type equations under monotonicity
  assumptions

abstract:
  We consider inverse problems for $p$-Laplace type equations under
monotonicity assumptions. In two dimensions, we show that any two
conductivities satisfying $\sigma_1 \geq \sigma_2$ and having the same
nonlinear Dirichlet-to-Neumann map must be identical. The proof is based on a
monotonicity inequality and the unique continuation principle for $p$-Laplace
type equations. In higher dimensions, where unique continuation is not known,
we obtain a similar result for conductivities close to constant.


title: $\mathfrak{M}_H(G)$-property and congruence of Galois representations

abstract:
  In this paper, we study the Selmer groups of two congruent Galois
representations over an admissible $p$-adic Lie extension. We will show that
under appropriate congruence condition, if the dual Selmer group of one
satisfies the $\M_H(G)$-property, so will the other. In the event that the
$\M_H(G)$-property holds, and assuming certain further hypothesis on the
decomposition of primes in the $p$-adic Lie extension, we compare the ranks of
the $\pi$-free quotient of the two dual Selmer groups. We then apply our
results to compare the characteristic elements attached to the Selmer groups.
We also study the variation of the ranks of the $\pi$-free quotient of the dual
Selmer groups of specialization of a big Galois representation. We emphasis
that our results \textit{do not} assume the vanishing of the $\mu$-invariant.


title:
Blow up property for viscoelastic evolution equations on manifolds with
  conical degeneration

abstract:
  This paper is concerned with the study of the nonlinear viscoelastic
evolution equation with strong damping and source terms, described by \[u_{tt}
- \Delta_{\mathbb{B}}u + \int_{0}^{t}g(t-\tau)\Delta_{\mathbb{B}}u(\tau)d\tau +
f(x)u_{t}|u_{t}|^{m-2} = h(x)|u|^{p-2}u , \hspace{1 cm} x\in int\mathbb{B}, t >
0,\] where $\mathbb{B}$ is a stretched manifold. First, we prove the solutions
of problem {1.1} in cone Sobolev space
$\mathcal{H}^{1,\frac{n}{2}}_{2,0}(\mathbb{B}),$ admit a blow up in finite time
for $p > m$ and positive initial energy. Then, we construct a lower bound for
obtained blow up time under appropriate assumptions on data.


title: GitHub open source project recommendation system

abstract:
  Hosting platforms for software projects can form collaborative social
networks and a prime example of this is GitHub which is arguably the most
popular platform of this kind. An open source project recommendation system
could be a major feature for a platform like GitHub, enabling its users to find
relevant projects in a fast and simple manner. We perform network analysis on a
constructed graph based on GitHub data and present a recommendation system that
uses link prediction.


title: Topological Superfluids

abstract:
  There are many topological faces of the superfluid phases of $^3$He. These
superfluids contain various topological defects and textures. The momentum
space topology of these superfluids is also nontrivial, as well as the topology
in the combined (${\bf p},{\bf r})$ phase space, giving rise to topologically
protected Dirac, Weyl and Majorana fermions living in bulk, on the surface and
within the topological objects. The nontrivial topology lead to different types
of anomalies, which extended in many different directions the
Landau-Khalatninkov theory of superfluidity.


title: How SN Ia host-galaxy properties affect cosmological parameters

abstract:
  We present a systematic study of the relationship between Type Ia Supernova
(SN Ia) properties, and the characteristics of their host galaxies, using a
sample of 581 SNe Ia from the full Sloan Digital Sky Survey II (SDSS-II) SN
Survey. We also investigate the effects of this on the cosmological constraints
derived from SNe~Ia. Compared to previous studies, our sample is larger by a
factor of $>4$, and covers a substantially larger redshift range (up to z~0.5),
which is directly applicable to the volume of cosmological interest. We measure
a significant correlation (>5\sigma) between the host-galaxy stellar-mass and
the SN~Ia Hubble Residuals (HR). We find a weak correlation (1.4\sigma) between
the host-galaxy metallicity as measured from emission lines in the spectra, and
the SN~Ia HR. We also find evidence that the slope of the correlation between
host-galaxy mass and HR is -0.11
$\mathrm{mag}/\mathrm{log}(\mathrm{M}_{\mathrm{host}}/\mathrm{M}_{\odot})$
steeper in lower metallicity galaxies. We test the effects on a cosmological
analysis using both the derived best-fitting correlations between host
parameters and HR, and by allowing an additional free parameter in the fit to
account for host properties which we then marginalize over when determining
cosmological parameters. We see a shift towards more negative values of the
equation of state parameter $w$, along with a shift to lower values of
$\Omega_\mathrm{m}$ after applying mass or metallicity corrections. The shift
in cosmological parameters with host-galaxy stellar-mass correction is
consistent with previous studies. We find a best-fitting cosmology of
$\Omega_{\mathrm{m}} =0.266_{-0.016}^{+0.016}$,
$\Omega_{\Lambda}=0.740_{-0.018}^{+0.018}$ and $w=-1.151_{-0.121}^{+0.123}$
(statistical errors only).


title:
Corrected Discrete Approximations for the Conditional and Unconditional
  Distributions of the Continuous Scan Statistic

abstract:
  The (conditional or unconditional) distribution of the continuous scan
statistic in a one-dimensional Poisson process may be approximated by that of a
discrete analogue via time discretization (to be referred to as the discrete
approximation). With the help of a change-of-measure argument, we derive the
first-order term of the discrete approximation which involves some functionals
of the Poisson process. Richardson's extrapolation is then applied to yield a
corrected (second-order) approximation. Numerical results are presented to
compare various approximations.


title:
Cooperative output regulation of multi-agent network systems with
  dynamic edges

abstract:
  This paper investigates a new class of linear multi-agent network systems, in
which nodes are coupled by dynamic edges in the sense that each edge has a
dynamic system attached as well. The outputs of the edge dynamic systems form
the external inputs of the node dynamic systems, which are termed "neighboring
inputs" representing the coupling actions between nodes. The outputs of the
node dynamic systems are the inputs of the edge dynamic systems. Several
cooperative output regulation problems are posed, including output
synchronization, output cooperation and master-slave output cooperation. Output
cooperation is specified as making the neighboring input, a weighted sum of
edge outputs, track a predefined trajectory by cooperation of node outputs.
Distributed cooperative output regulation controllers depending on local state
and neighboring inputs are presented, which are designed by combining feedback
passivity theories and the internal model principle. A simulation example on
the cooperative current control of an electrical network illustrates the
potential applications of the analytical results.


title:
Estimates of the temperature flux-temperature gradient relation above a
  sea-floor

abstract:
  The relation between the flux of temperature (or buoyancy), the vertical
temperature gradient and the height above the bottom, is investigated in an
oceanographic context, using high-resolution temperature measurements. The
model for the evolution of a stratified layer by Balmforth et al. (1998) is
reviewed and adapted to the case of a turbulent flow above a wall. Model
predictions are compared to the average observational estimates of the flux,
exploiting a flux estimation method proposed by Winters & D'Asaro (1996). This
estimation method enables the disentanglement of the dependence of the average
flux on the height above the bottom and on the background temperature gradient.
The classical N-shaped flux-gradient relation is found in the observations.
Model and observations show similar qualitative behaviour, despite the strong
simplifications used in the model. The results shed light on the modulation of
the temperature flux by the presence of the boundary, and support the idea of a
turbulent flux following a mixing-length argument in a stratified flow.
Furthermore, the results support the use of Thorpe scales close to a boundary,
if sufficient averaging is performed, suggesting that the Thorpe scales are
affected by the boundary in a similar way as the mixing length.