title:
Electrical Addressing and Temporal Tweezing of Localized Pulses in
  Passively Mode-Locked Semiconductor Lasers

abstract:
  We show that the pumping current is a convenient parameter for manipulating
the temporal Localized Structures (LSs), also called localized pulses, found in
passively mode-locked Vertical-Cavity Surface-Emitting Lasers. While short
electrical pulses can be used for writing and erasing individual LSs, we
demonstrate that a current modulation introduces a temporally evolving
parameter landscape allowing to control the position and the dynamics of LSs.
We show that the localized pulses drifting speed in this landscape depends
almost exclusively on the local parameter value instead of depending on the
landscape gradient, as shown in quasi-instantaneous media. This experimental
observation is theoretically explained by the causal response time of the
semiconductor carriers that occurs on an finite timescale and breaks the parity
invariance along the cavity, thus leading to a new paradigm for temporal
tweezing of localized pulses. Different modulation waveforms are applied for
describing exhaustively this paradigm. Starting from a generic model of passive
mode-locking based upon delay differential equations, we deduce the effective
equations of motion for these LSs in a time-dependent current landscape.


title:
Bell nonlocality and fully-entangled fraction measured in an
  entanglement-swapping device without quantum state tomography

abstract:
  We demonstrate an efficient experimental procedure based on entanglement
swapping to determine the Bell nonlocality measure of Horodecki et al. [Phys.
Lett. A 200, 340 (1995)] and the fully-entangled fraction of Bennett et al.
[Phys. Rev. A 54, 3824 (1996)] of an arbitrary two-qubit polarization-encoded
state. The nonlocality measure corresponds to the amount of the violation of
the Clauser-Horne-Shimony-Holt (CHSH) optimized over all measurement settings.
By using simultaneously two copies of a given state, we measure directly only
six parameters. Our method requires neither full quantum state tomography of 15
parameters nor continuous scanning of the measurement bases used by two parties
in the usual CHSH inequality tests with four measurements in each optimization
step. We analyze how well the measured degrees of Bell nonlocality and other
entanglement witnesses (including the fully-entangled fraction and a nonlinear
entropic witness) of an arbitrary two-qubit state can estimate its
entanglement. In particular, we measured these witnesses and estimated the
negativity of various two-qubit Werner states. Our approach could especially be
useful for quantum communication protocols based on entanglement swapping.


title: ERA Revisited: Theoretical and Experimental Evaluation

abstract:
  Efficient construction of the suffix tree given an input text is an active
area of research from the time it was first introduced. Both theoretical
computer scientists and engineers tackled the problem. In this paper we focus
on the fastest practical suffix tree construction algorithm to date, ERA. We
first provide a theoretical analysis of the algorithm assuming the uniformly
random text as an input and using the PEM model of computation with respect to
the lower bounds. Secondly, we empirically confirm the theoretical results in
different test scenarios exposing the critical terms. Thirdly, we discuss the
fundamental characteristics of the input text where the fastest suffix tree
construction algorithms in practice fail. This paper serves as a foundation for
further research in the parallel text indexing area.


title:
Analytical computation of stray light in nested mirror modules for X-ray
  telescopes

abstract:
  Stray light in X-ray telescopes is a well-known issue. Unlike rays focused
via a double reflection by usual grazing-incidence geometries such as the
Wolter-I, stray rays coming from off-axis sources are reflected only once by
either the parabolic or the hyperbolic segment. Although not focused, stray
light may represent a major source of background and ghost images especially
when observing a field of faint sources in the vicinities of another, more
intense, just outside the field of view of the telescope. The stray light
problem is faced by mounting a pre-collimator in front of the mirror module, in
order to shade a part of the reflective surfaces that may give rise to
singly-reflected rays. Studying the expected stray light impact, and
consequently designing a pre-collimator, is a typical ray-tracing problem,
usually time and computation consuming, especially if we consider that rays
propagate throughout a densely nested structure. This in turn requires one to
pay attention to all the possible obstructions, increasing the complexity of
the simulation. In contrast, approaching the problems of stray light
calculation from an analytical viewpoint largely simplifies the problem, and
may also ease the task of designing an effective pre-collimator. In this work
we expose an analytical formalism that can be used to compute the stray light
in a nested optical module in a fast and effective way, accounting for
obstruction effects.


title: Automated Enterprise Applications Generation from Requirements Model

abstract:
  Enterprise applications can be automatically generated from a sophisticated
OO design model based on model-driven approach. The design model contains
information about how to decompose the system into components, how to
encapsulate the system operations into classes, and how the objects of classes
collaborate to fulfill the functionality of the system operations. However, the
efforts to build the design model from a validated requirements model are not
proportional to the return. In practice, it is very desirable to have an
approach that can automatically generate standardized enterprise applications
directly from the validated requirements models. In this paper, we propose an
approach named RM2EA, which can reach this goal based on the contract-based
requirements model. We demonstrate the proposed approach through 13 case
studies. The evaluation result shows that the quality and efficiency of the
generated applications are almost equal to the applications implemented by
developers: firstly, we demonstrate that a popular type of enterprise
applications (i.e., a Jakarta EE application) can be successfully generated by
customizing and improving the set of rules; secondly, RM2EA can generate more
readable or maintainable code; thirdly, the enterprise applications generated
by RM2EA achieve similar performance in test results. Overall, the result is
satisfactory, and the implementation of the proposed approach can be further
enhanced and applied to software development in the industry.


title:
On exact Hausdorff measure functions of operator semistable L\'evy
  processes

abstract:
  Let $X=\{X(t)\}_{t\geq0}$ be an operator semistable L\'evy process on
$\mathbb{R}^d$ with exponent $E$, where $E$ is an invertible linear operator on
$\mathbb{R}^d$. In this paper we determine exact Hausdorff measure functions
for the range of $X$ over the time interval $[0,1]$ under certain assumptions
on the principal spectral component of $E$. As a byproduct we also present
Tauberian results for semistable subordinators and sharp bounds for the
asymptotic behavior of the expected sojourn times of $X$.


title: May axion clusters be sources of fast radio bursts?

abstract:
  Fast radio bursts can be caused by some phenomena related to 'new
physics'.One of the most prominent candidates of the kind are axion Bose stars
which can engender bursts when undergoing conversion into photons in
magnetospheres of neutron stars or during their collapse. In this short
research note an importance of three observational criteria is outlined, namely
total energetic, $\mathcal{O}$(ms) duration and non-monochromatic shape of the
spectrum. It is shown that it is impossible to meet these criteria in
simplified models of axion-neutron star interaction scenario and thorough
investigation of more complex models which involve back-reaction and non-linear
effects are needed in order to explain FRBs within this scenario.


title: Two band model for coherent excitonic condensates

abstract:
  We consider the excitonic correlations in the two band solid state system
composed of the valence band and conduction band electrons. We treat the phase
coherence mechanism in the system by presenting the electron operator as a
fermion attached to the U(1) phase-flux tube. The emergent bosonic gauge field,
related to the phase variables appears to be crucial for the coherent
Bose-Einstein condensation (BEC) of excitons. We calculate the normal excitonic
Green functions, and the single-particle density of states functions being a
convolution between bosonic and fermionic counterparts. We obtain the total
density of states (DOS) as a sum of two independent parts. For the coherent
normal fermionic DOS, there is no hybridization-gap found in the system due to
strong coherence effets and phase stiffness.


title:
On Identification of Sparse Multivariable ARX Model: A Sparse Bayesian
  Learning Approach

abstract:
  This paper begins with considering the identification of sparse linear
time-invariant networks described by multivariable ARX models. Such models
possess relatively simple structure thus used as a benchmark to promote further
research. With identifiability of the network guaranteed, this paper presents
an identification method that infers both the Boolean structure of the network
and the internal dynamics between nodes. Identification is performed directly
from data without any prior knowledge of the system, including its order. The
proposed method solves the identification problem using Maximum a posteriori
estimation (MAP) but with inseparable penalties for complexity, both in terms
of element (order of nonzero connections) and group sparsity (network
topology). Such an approach is widely applied in Compressive Sensing (CS) and
known as Sparse Bayesian Learning (SBL). We then propose a novel scheme that
combines sparse Bayesian and group sparse Bayesian to efficiently solve the
problem. The resulted algorithm has a similar form of the standard Sparse Group
Lasso (SGL) while with known noise variance, it simplifies to exact re-weighted
SGL. The method and the developed toolbox can be applied to infer networks from
a wide range of fields, including systems biology applications such as
signaling and genetic regulatory networks.


title:
Joint Channel Estimation / Data Detection in MIMO-FBMC/OQAM Systems - A
  Tensor-Based Approach

abstract:
  Filter bank-based multicarrier (FBMC) systems are currently being considered
as a prevalent candidate for replacing the long established cyclic prefix
(CP)-based orthogonal frequency division multiplexing (CP-OFDM) in the physical
layer of next generation communications systems. In particular, FBMC/OQAM has
received increasing attention due to, among other features, its potential for
maximum spectral efficiency. It suffers, however, from an intrinsic
self-interference effect, which complicates signal processing tasks at the
receiver, including synchronization, channel estimation and equalization. In a
multiple-input multiple-output (MIMO) configuration, the multi-antenna
interference has also to be taken into account. (Semi-)blind FBMC/OQAM
receivers have been little studied so far and mainly for single-antenna
systems. The problem of joint channel estimation and data detection in a
MIMO-FBMC/OQAM system, given limited or no training information, is studied in
this paper through a tensor-based approach in the light of the success of such
techniques in OFDM applications. Simulation-based comparisons with CP-OFDM are
included, for realistic transmission models.


title: Groups whose locally maximal product-free sets are complete

abstract:
  Let $G$ be a finite group and $S$ a subset of $G$. Then $S$ is product-free
if $S \cap SS = \emptyset$, and complete if $G^{\ast} \subseteq S \cup SS$. A
product-free set is locally maximal if it is not contained in a strictly larger
product-free set. If $S$ is product-free and complete then $S$ is locally
maximal, but the converse does not necessarily hold. Street and Whitehead [J.
Combin. Theory Ser. A 17 (1974), 219--226] defined a group $G$ as filled if
every locally maximal product-free set $S$ in $G$ is complete (the term comes
from their use of the phrase `$S$ fills $G$' to mean $S$ is complete). They
classified all abelian filled groups, and conjectured that the finite dihedral
group of order $2n$ is not filled when $n=6k+1$ ($k\geq 1$). The conjecture was
disproved by two of the current authors in [Austral. J. Combin. 63 (3) (2015),
385--398], where we also classified the filled groups of odd order. In this
paper we classify filled dihedral groups, filled nilpotent groups and filled
groups of order $2^np$ where $p$ is an odd prime. We use these results to
determine all filled groups of order up to 2000.


title: Zero-divisor graphs of lower dismantlable lattices-II

abstract:
  In this paper, we continue our study of the zero-divisor graphs of lower
dismantlable lattices that was started in [20]. The present paper mainly deals
with an Isomorphism Problem for the zero-divisor graphs of lattices. In fact,
we prove that the zero-divisor graphs of lower dismantlable lattices with the
greatest element 1 as join-reducible are isomorphic if and only if the lattices
are isomorphic.


title:
Galactic outflow driven by the active nucleus and the origin of the
  gamma-ray emission in NGC 1068

abstract:
  We compute the non-thermal emissions produced by relativistic particles
accelerated by the AGN-driven shocks in NGC 1068, and we compare the model
predictions with the observed gamma-ray and radio spectra . The former is
contributed by pion decay, inverse Compton scattering, and bremsstrahlung,
while the latter is produced by synchrotron radiation. We derive the gamma-ray
and radio emissions by assuming the standard acceleration theory, and we
discuss how our results compare with those corresponding to other commonly
assumed sources of gamma-ray and radio emissions, like Supernova remnants (SNR)
or AGN jets. We find that the AGN-driven shocks observed in the circumnuclear
molecular disk of such a galaxy provide a contribution to the gamma-ray
emission comparable to that provided by the starburst activity when standard
particle acceleration efficiencies are assumed, while they can yield the whole
gamma-ray emission only when the parameters describing the acceleration
efficiency and the proton coupling with the molecular gas are tuned to values
larger than those assumed in standard, SNR-driven shocks. We discuss the range
of acceleration efficiencies (for protons and electrons) and of proton
calorimetric fractions required to account for the observed gamma-ray emission
in the AGN outflow model. We further compare the neutrino flux expected in our
model with constraints from current experiments, and we provide predictions for
the detections by the upcoming KM3NeT neutrino telescope. This analysis
strongly motivates observations of NGC 1068 at >TeV energies with current and
future Cherenkov telescopes in order to gain insight into the nature of the
gamma-rays source.


title: Inverse mean curvature flows in warped product manifolds

abstract:
  We study inverse mean curvature flows of starshaped, mean convex
hypersurfaces in warped product manifolds with a positive warping factor
$\varphi(r)$. If $\varphi'(r)>0$ and $\varphi''(r)\geq 0$, we show that these
flows exist for all times, remain starshaped and mean convex. Plus the
positivity of $\varphi''(r)$ and a curvature condition we obtain a lower
positive bound of mean curvature along these flows independent of the initial
mean curvature. We also give a sufficient condition to extend the asymptotic
behavior of these flows in Euclidean spaces into some more general warped
product manifolds.


title:
A historical introduction to the symmetries of magnetic structures: Part
  1. Early quantum theory, neutron powder diffraction and the colored space
  groups

abstract:
  This paper introduces the historical development of the symmetries for
describing magnetic structures culminating in the derivation of the black and
white and colored space groups. Beginning from the Langevin model of the Curie
law, it aims to show the challenges that magnetic ordering presented and how
different symmetry frameworks were developed to meet them. As well as
explaining core ideas, later papers will show how the different schemes are
connected. With these goals in mind, the maths related is kept to the minimum
required for clarity.


title: Pseudo-Hermitian Hamiltonians Generating Waveguide Mode Evolution

abstract:
  We study the properties of Hamiltonians defined as the generators of transfer
matrices in quasi- one-dimensional waveguides. For single- or multi-mode
waveguides obeying flux conservation and time-reversal invariance, the
Hamiltonians defined in this way are non-Hermitian, but satisfy symmetry
properties that have previously been identified in the literature as "pseudo
Hermiticity" and "anti-PT symmetry". We show how simple one-channel and
two-channel models exhibit transitions between real, imaginary, and complex
eigenvalue pairs.


title: Cramer's rules for Hermitian systems of coquaternionic equations

abstract:
  In this paper properties of the determinant of a Hermitian matrix are
investigated, and determinantal representations of the inverse of a Hermitian
coquaternionic matrix are given. By their using, Cramer's rules for left and
right systems of linear equations with Hermitian coquaternionic matrices of
coefficients are obtained. Cramer's rule for a two-sided coquaternionic matrix
equation ${\bf AXB}={\bf D}$ (with Hermitian ${\bf A}$, ${\bf B}$) is given as
well.


title: Relative two-weight $\mathbb{Z}_2 \mathbb{Z}_4$-additive Codes

abstract:
  In this paper, we study a relative two-weight $\mathbb{Z}_2
\mathbb{Z}_4$-additive codes. It is shown that the Gray image of a two-distance
$\mathbb{Z}_2 \mathbb{Z}_4$-additive code is a binary two-distance code and
that the Gray image of a relative two-weight $\mathbb{Z}_2
\mathbb{Z}_4$-additive code, with nontrivial binary part, is a linear binary
relative two-weight code. The structure of relative two-weight $\mathbb{Z}_2
\mathbb{Z}_4$-additive codes are described. Finally, we discussed permutation
automorphism group of a $\mathbb{Z}_2 \mathbb{Z}_4$-additive codes.


title: Graded Frobenius cluster categories

abstract:
  Recently the first author studied multi-gradings for generalised cluster
categories, these being 2-Calabi-Yau triangulated categories with a choice of
cluster-tilting object. The grading on the category corresponds to a grading on
the cluster algebra without coefficients categorified by the cluster category
and hence knowledge of one of these structures can help us study the other.
  In this work, we extend the above to certain Frobenius categories that
categorify cluster algebras with coefficients. We interpret the grading
K-theoretically and prove similar results to the triangulated case, in
particular obtaining that degrees are additive on exact sequences.
  We show that the categories of Buan, Iyama, Reiten and Scott, some of which
were used by Geiss, Leclerc and Schroer to categorify cells in partial flag
varieties, and those of Jensen, King and Su, categorifying Grassmannians, are
examples of graded Frobenius cluster categories.


title: Caffeinated FPGAs: FPGA Framework For Convolutional Neural Networks

abstract:
  Convolutional Neural Networks (CNNs) have gained significant traction in the
field of machine learning, particularly due to their high accuracy in visual
recognition. Recent works have pushed the performance of GPU implementations of
CNNs to significantly improve their classification and training times. With
these improvements, many frameworks have become available for implementing CNNs
on both CPUs and GPUs, with no support for FPGA implementations. In this work
we present a modified version of the popular CNN framework Caffe, with FPGA
support. This allows for classification using CNN models and specialized FPGA
implementations with the flexibility of reprogramming the device when
necessary, seamless memory transactions between host and device, simple-to-use
test benches, and the ability to create pipelined layer implementations. To
validate the framework, we use the Xilinx SDAccel environment to implement an
FPGA-based Winograd convolution engine and show that the FPGA layer can be used
alongside other layers running on a host processor to run several popular CNNs
(AlexNet, GoogleNet, VGG A, Overfeat). The results show that our framework
achieves 50 GFLOPS across 3x3 convolutions in the benchmarks. This is achieved
within a practical framework, which will aid in future development of
FPGA-based CNNs.


title: Hyperbolic volume estimates via train tracks

abstract:
  In this thesis we describe how to estimate the distance spanned in the pants
graph by a train track splitting sequence on a surface, up to multiplicative
and additive constants. If some moderate assumptions on a splitting sequence
are satisfied, each vertex set of a train track in it will represent a vertex
of a graph which is naturally quasi-isometric to the pants graph; moreover the
splitting sequence gives an edge-path in this graph so, more precisely, our
distance estimate holds between the extreme points of this path. The present
distance estimate is inspired by a result of Masur, Mosher and Schleimer for
distances in the marking graph. However, we can apply their line of proof only
after some manipulation of the splitting sequence: a rearrangement, changing
the order the elementary moves are performed in, so that the ones producing
Dehn twists are brought together; and then an untwisting, which suppresses the
majority of these latter moves to give a new sequence, which does not end with
the same track as before, but does not include any portion that is almost
stationary in the pants graph. The required distance is then, up to constants,
the number of splits occurring in the untwisted sequence. A consequence of our
main theorem together with a result of Brock is that, given a pseudo-Anosov
self-diffeomorphism $\psi$ of a surface $S$, the maximal splitting sequence
introduced by Agol gives us an estimate for the hyperbolic volume of the
mapping torus built from $S$ and $\psi$. There are also some interesting
consequences for the hyperbolic volume of a solid torus minus a closed braid,
via a machinery employed by Dynnikov and Wiest.


title: A view on the open STIRAP problem

abstract:
  We consider the open STIRAP problem by formulating it in terms of generalized
Bloch equations. Expressed in this form the resulting Liouvillian matrix is
analyzed in detail. As it turns out, most of the findings of open STIRAP models
can be understood from the spectrum and eigenstates of the Liouvillian matrix.
As a non-hermitian matrix we particularly discuss the mathematical structure of
it by identifying among others the physical meaning of its eigenvectors and the
system's exceptional points. We also discuss the importance of the Liouvillian
gap which normally implies that any state becomes mixed. However, in certain
situations, for example the STIRAP model under influence of spontaneous
emission, a sort of pump term appears in the equations of motion, and its
effect is to counteract the gap induced decay such that coherence may prevail.
As the STIRAP driving is not perfectly adiabatic, we additionally find that for
spontaneous emission the presence of a non-zero Liouvillian gap actually
enhances the success rate of the process. This is thus an example of a
environment assisted physical operation.


title: Asymptotics for time-changed diffusions

abstract:
  We consider time-changed diffusions driven by generators with discontinuous
coefficients. The PDE's connections are investigated and in particular some
results on the asymptotic analysis according to the behaviour of the
coefficients are presented.


title: Algebraic and logical descriptions of generalized trees

abstract:
  Quasi-trees generalize trees in that the unique "path" between two nodes may
be infinite and have any countable order type. They are used to define the
rank-width of a countable graph in such a way that it is equal to the least
upper-bound of the rank-widths of its finite induced subgraphs. Join-trees are
the corresponding directed trees. They are useful to define the modular
decomposition of a countable graph. We also consider ordered join-trees, that
generalize rooted trees equipped with a linear order on the set of sons of each
node. We define algebras with finitely many operations that generate (via
infinite terms) these generalized trees. We prove that the associated regular
objects (those defined by regular terms) are exactly the ones that are the
unique models of monadic second-order sentences. These results use and
generalize a similar result by W. Thomas for countable linear orders.


title: Thermal Stability of Diamond-Like Carbon Nanothreads

abstract:
  The thermally activated fracture processes in the carbon backbone of
diamond-like carbon nanothreads and the hydrogen desorption from them has been
studied by the molecular dynamics method. Specifically, the temperature
dependence of the characteristic desorption time at T = 1700-2800 K has been
determined. The activation energy and frequency factor in the Arrhenius formula
for the desorption rate are found. This allows estimating the desorption time
at any temperature. The mechanical stiffness of nanothreads is calculated.


title:
BEaTriX, expanded X-ray beam facility for testing modular elements of
  telescope optics: an update

abstract:
  We present in this paper an update on the design of BEaTriX (Beam Expander
Testing X-ray facility), an X-ray apparatus to be realized at INAF/OAB and that
will generate an expanded, uniform and parallel beam of soft X-rays. BEaTriX
will be used to perform the functional tests of X-ray focusing modules of large
X-ray optics such as those for the ATHENA X-ray observatory, using the Silicon
Pore Optics (SPO) as a baseline technology, and Slumped Glass Optics (SGO) as a
possible alternative. Performing the tests in X-rays provides the advantage of
an in-situ, at-wavelength quality control of the optical modules produced in
series by the industry, performing a selection of the modules with the best
angular resolution, and, in the case of SPOs, there is also the interesting
possibility to align the parabolic and the hyperbolic stacks directly under
X-rays, to minimize the aberrations. However, a parallel beam with divergence
below 2 arcsec is necessary in order to measure mirror elements that are
expected to reach an angular resolution of about 4 arcsec, since the ATHENA
requirement for the entire telescope is 5 arcsec. Such a low divergence over
the typical aperture of modular optics would require an X-ray source to be
located in a several kilometers long vacuum tube. In contrast, BEaTriX will be
compact enough (5 m x 14 m) to be housed in a small laboratory, will produce an
expanded X-ray beam 60 mm x 200 mm broad, characterized by a very low
divergence (1.5 arcsec HEW), strong polarization, high uniformity, and X-ray
energy selectable between 1.5 keV and 4.5 keV. In this work we describe the
BEaTriX layout and show a performance simulation for the X-ray energy of 4.5
keV.


title: Impact of scalar leptoquarks on heavy baryonic decays

abstract:
  We present a study on the impact of scalar leptoquarks on the semileptonic
decays of $ \Lambda_b$, $\Sigma_b $ and $\Xi_b $. To this end, we calculate the
differential branching ratio and lepton forward-backward asymmetry defining the
processes $ \Lambda_b \rightarrow \Lambda \ell^+ \ell^-$, $\Sigma_b \rightarrow
\Sigma \ell^+ \ell^-$ and $\Xi_b \rightarrow \Xi \ell^+ \ell^-$, with $\ell$
being $\mu$ or $\tau$, using the form factors calculated via light cone QCD in
full theory. In calculations, the errors of form factors are taken into
account. We compare the results obtained in leptoquark model with those of the
standard model as well as the existing lattice QCD predictions and experimental
data.


title: Clustered Planarity with Pipes

abstract:
  We study the version of the C-Planarity problem in which edges connecting the
same pair of clusters must be grouped into pipes, which generalizes the Strip
Planarity problem. We give algorithms to decide several families of instances
for the two variants in which the order of the pipes around each cluster is
given as part of the input or can be chosen by the algorithm.


title:
Partial Regularity of Solutions to the Second Boundary Value Problem for
  Generated Jacobian Equations

abstract:
  We prove that outside of a closed singular set of measure zero solutions to
the second boundary value problem for generated Jacobian equations are smooth.


title: Predicting the consequence of action in digital control state spaces

abstract:
  The objective of this dissertation is to shed light on some fundamental
impediments in learning control laws in continuous state spaces. In particular,
if one wants to build artificial devices capable to learn motor tasks the same
way they learn to classify signals and images, one needs to establish control
rules that do not necessitate comparisons between quantities of the surrounding
space. We propose, in that context, to take inspiration from the "end effector
control" principle, as suggested by neuroscience studies, as opposed to the
"displacement control" principle used in the classical control theory.


title:
Soft Cache Hits and the Impact of Alternative Content Recommendations on
  Mobile Edge Caching

abstract:
  Caching popular content at the edge of future mobile networks has been widely
considered in order to alleviate the impact of the data tsunami on both the
access and backhaul networks. A number of interesting techniques have been
proposed, including femto-caching and "delayed" or opportunistic cache access.
Nevertheless, the majority of these approaches suffer from the rather limited
storage capacity of the edge caches, compared to the tremendous and rapidly
increasing size of the Internet content catalog. We propose to depart from the
assumption of hard cache misses, common in most existing works, and consider
"soft" cache misses, where if the original content is not available, an
alternative content that is locally cached can be recommended. Given that
Internet content consumption is increasingly entertainment-oriented, we believe
that a related content could often lead to complete or at least partial user
satisfaction, without the need to retrieve the original content over expensive
links. In this paper, we formulate the problem of optimal edge caching with
soft cache hits, in the context of delayed access, and analyze the expected
gains. We then show using synthetic and real datasets of related video contents
that promising caching gains could be achieved in practice.


title:
Testing multilayer-coated polarizing mirrors for the LAMP soft X-ray
  telescope

abstract:
  The LAMP (Lightweight Asymmetry and Magnetism Probe) X-ray telescope is a
mission concept to measure the polarization of X-ray astronomical sources at
250 eV via imaging mirrors that reflect at incidence angles near the
polarization angle, i.e., 45 deg. Hence, it will require the adoption of
multilayer coatings with a few nanometers d-spacing in order to enhance the
reflectivity. The nickel electroforming technology has already been
successfully used to fabricate the high angular resolution imaging mirrors of
the X-ray telescopes SAX, XMM-Newton, and Swift/XRT. We are investigating this
consolidated technology as a possible technique to manufacture focusing mirrors
for LAMP. Although the very good reflectivity performances of this kind of
mirrors were already demonstrated in grazing incidence, the reflectivity and
the scattering properties have not been tested directly at the unusually large
angle of 45 deg. Other possible substrates are represented by thin glass foils
or silicon wafers. In this paper we present the results of the X-ray
reflectivity campaign performed at the BEAR beamline of Elettra - Sincrotrone
Trieste on multilayer coatings of various composition (Cr/C, Co/C), deposited
with different sputtering parameters on nickel, silicon, and glass substrates,
using polarized X-rays in the spectral range 240 - 290 eV.


title: Thoroughly Distributed Colorings

abstract:
  We consider (not necessarily proper) colorings of the vertices of a graph
where every color is thoroughly distributed, that is, appears in every open
neighborhood. Equivalently, every color is a total dominating set. We define
$\td(G)$ as the maximum number of colors in such a coloring and $\FTD(G)$ as
the fractional version thereof. In particular, we show that every claw-free
graph with minimum degree at least~$2$ has~$\FTD(G)\ge 3/2$ and this is best
possible. For planar graphs, we show that every triangular disc has $\FTD(G)
\ge 3/2$ and this is best possible, and that every planar graph has $\td(G) \le
4$ and this is best possible, while we conjecture that every planar
triangulation has $\td(G)\ge 2$. Further, although there are arbitrarily large
examples of connected, cubic graphs with $\td(G)=1$, we show that for a
connected cubic graph $\FTD(G) \ge 2-o(1)$, and conjecture that it is always at
least~$2$. We also consider the related concepts in hypergraphs.


title: Lattice Boltzmann modelling of intrinsic permeability

abstract:
  Lattice Boltzmann method (LBM) has been applied to predict flow properties of
porous media including intrinsic permeability, where it is implicitly assumed
that the LBM is equivalent to the incompressible (or near incompressible)
Navier-Stokes equation. However, in LBM simulations, high-order moments, which
are completely neglected in the Navier-Stokes equation, are still available
through particle distribution functions. To ensure that the LBM simulation is
correctly working at the Navier-Stokes hydrodynamic level, the high-order
moments have to be negligible. This requires that the Knudsen number (Kn) is
small so that rarefaction effect can be ignored. In this technical note, we
elaborate this issue in LBM modelling of porous media flows, which is
particularly important for gas flows in ultra-tight media.


title:
Strong factorization property of Macdonald polynomials and higher-order
  Macdonald's positivity conjecture

abstract:
  We prove a strong factorization property of interpolation Macdonald
polynomials when $q$ tends to $1$. As a consequence, we show that Macdonald
polynomials have a strong factorization property when $q$ tends to $1$, which
was posed as an open question in our previous paper with F\'eray. Furthermore,
we introduce multivariate $q,t$-Kostka numbers and we show that they are
polynomials in $q,t$ with integer coefficients by using the strong
factorization property of Macdonald polynomials. We conjecture that
multivariate $q,t$-Kostka numbers are in fact polynomials in $q,t$ with
nonnegative integer coefficients, which generalizes the celebrated Macdonald's
positivity conjecture.


title:
Correlated spontaneous emission of fluorescent emitters mediated by
  single plasmons

abstract:
  Manipulating the spontaneous emission of a fluorescent emitter can be
achieved by placing the emitter in a nanostructured environment. A privileged
spot is occupied by plasmonic structures that provide a strong confinement of
the electromagnetic field, which results in an enhancement of the
emitter-environment interaction. While plasmonic nanostructures have been
widely exploited to control the emission properties of single photon emitters,
performing the coupling between quantum emitters with plasmons poses a huge
challenge. In this Letter we report on a first crucial step towards this goal
by the observation of correlated emission between a single CdSe/CdS/ZnS quantum
dot exhibiting single photon statistics and a fluorescent nanobead located
micrometers apart. This is accomplished by coupling both emitters to a silver
nanowire. Single-plasmons are created on the latter from the quantum dot, and
transfer energy to excite in turn the fluorescent nanobead.


title: Mapping cones in the bounded derived category of a gentle algebra

abstract:
  In this article we describe the triangulated structure of the bounded derived
category of a gentle algebra by describing the triangles induced by the
morphisms between indecomposable objects in a basis of their Hom-space.


title: Contextuality in multipartite pseudo-telepathy graph games

abstract:
  Analyzing pseudo-telepathy graph games, we propose a way to build
contextuality scenarios exhibiting the quantum supremacy using graph states. We
consider the combinatorial structures that generate equivalent scenarios. We
introduce a new tool called multipartiteness width to investigate which
scenarios are harder to decompose and show that there exist graphs generating
scenarios with a linear multipartiteness width.


title: Chiral magnetism of magnetic adatoms generated by Rashba electrons

abstract:
  We investigate long-range chiral magnetic interactions among adatoms mediated
by surface states spin-splitted by spin-orbit coupling. Using the Rashba model,
the tensor of exchange interactions is extracted wherein a pseudo-dipolar
interaction is found besides the usual isotropic exchange interaction and the
Dzyaloshinskii-Moriya interaction. We find that, despite the latter
interaction, collinear magnetic states can still be stabilized by the
pseudo-dipolar interaction. The inter-adatom distance controls the strength of
these terms, which we exploit to design chiral magnetism in Fe nanostructures
deposited on Au(111) surface. We demonstrate that these magnetic interactions
are related to superpositions of the out-of-plane and in-plane components of
the skyrmionic magnetic waves induced by the adatoms in the surrounding
electron gas. We show that, even if the inter-atomic distance is large, the
size and shape of the nanostructures dramatically impacts on the strength of
the magnetic interactions, thereby affecting the magnetic ground state. We also
derive an appealing connection between the isotropic exchange interaction and
the Dzyaloshinskii-Moriya interaction, which relates the latter to the first
order change of the former with respect to the spin-orbit coupling. This
implies that the chirality defined by the direction of the
Dzyaloshinskii-Moriya vector is driven by the variation of the isotropic
exchange interaction due to the spin-orbit interaction.


title: BCS pairing state of a Dilute Bose Gas with Spin-Orbit Coupling

abstract:
  We study a two-component Bose gas with a symmetric spin-orbit coupling, and
find that two atoms can form a bound state with any intra- or inter-species
scattering length. Consequently, in the dilute limit, the
Bardeen-Cooper-Shrieffer (BCS) pairing state of bosons can be formed with
weakly-attractive inter-species and repulsive intra-species interactions. The
quasiparticle excitation energies are anisotropic due to spin-orbit coupling.
This BCS paring state is energetically favored over Bose-Einstein condensation
(BEC) of atoms at low densities. As the density increases, there is a
first-order transition from the BCS to BEC states.


title:
Loss of boundary conditions for fully nonlinear parabolic equations with
  superquadratic gradient terms

abstract:
  We study whether the solutions of a fully nonlinear, uniformly parabolic
equation with superquadratic growth in the gradient satisfy initial and
homogeneous boundary conditions in the classical sense, a problem we refer to
as the classical Dirichlet problem. Our main results are: the nonexistence of
global-in-time solutions of this problem, depending on a specific largeness
condition on the initial data, and the existence of local-in-time solutions for
initial data $C^1$ up to the boundary. Global existence is know when boundary
conditions are understood in the viscosity sense, what is known as the
generalized Dirichlet problem. Therefore, our result implies loss of boundary
conditions in finite time. Specifically, that a solution satisfying homogeneous
boundary conditions in the viscosity sense eventually becomes strictly positive
at some point of the boundary.


title:
Critical adsorption of polyelectrolytes onto planar and convex highly
  charged surfaces: the nonlinear Poisson-Boltzmann approach

abstract:
  We study the adsorption-desorption transition of polyelectrolyte chains onto
planar, cylindrical and spherical surfaces with arbitrarily high surface charge
densities by massive Monte Carlo computer simulations. We examine in detail how
the well known scaling relations for the threshold transition-demarcating the
adsorbed and desorbed domains of a polyelectrolyte near weakly charged
surfaces-are altered for highly charged interfaces. In virtue of high surface
potentials and large surface charge densities, the Debye-Hueckel approximation
is often not feasible and the nonlinear Poisson-Boltzmann approach should be
implemented. At low salt conditions, for instance, the electrostatic potential
from the nonlinear Poisson--Boltzmann equation is smaller than the
Debye-Hueckel result, such that the required critical surface charge density
for polyelectrolyte adsorption $\sigma_c$ increases. The nonlinear relation
between the surface charge density and electrostatic potential leads to a
sharply increasing critical surface charge density with growing ionic strength,
imposing an additional limit to the critical salt concentration above which no
polyelectrolyte adsorption occurs at all. We contrast our simulations findings
with the known scaling results for weak critical polyelectrolyte adsorption
onto oppositely charged surfaces for the three standard geometries. Finally, we
discuss some applications of our results for some physical-chemical and
biophysical systems.


title: AlN-buffered superconducting NbN nanowire single-photon detector on GaAs

abstract:
  We investigated the suitability of AlN as a buffer layer for NbN
superconducting nanowire single-photon detectors (SNSPDs) on GaAs. The NbN
films with a thickness of 3.3 nm to 20 nm deposited onto GaAs substrates with
AlN buffer layer, demonstrate a higher critical temperature, critical current
density and lower residual resistivity in comparison to films deposited onto
bare substrates. Unfortunately, the thermal coupling of the NbN film to the
substrate weakens.
  SNSPDs made of 4.9 nm thick NbN films on buffered substrates (in comparison
to detectors made from NbN films on bare GaAs) demonstrate three orders of
magnitude lower dark count rates and about ten times higher detection
efficiency at 900 nm being measured at 90% of the critical current. The system
timing jitter of SNSPDs on buffered substrates is 72 ps which is 36 ps lower
than those on bare substrate. However, a weaker thermal coupling of NbN
nanowire to the buffered substrate leads to a latching effect at bias currents
> 0.97 IC.


title: Left-Separating Order Types

abstract:
  A well ordering < of a topological space X is "left-separating" if $\{x'\in
X: x'< x\}$ is closed in X for any x in X. A space is "left-separated" if it
has a left-separating well-ordering. The left-separating type, $ord_l(X)$, of a
left-separated space X is the minimum of the order types of the left-separating
well orderings of X.
  We prove that
  (1) if ${\kappa}$ is a regular cardinal, then for each ordinal
${\alpha}<{\kappa}^+$ there is a $T_2$ space $X$ with $ord_l(X)={\kappa}\cdot
{\alpha}$;
  (2) if ${\kappa}={\lambda}^+$ and $cf({\lambda})={\lambda}>{\omega}$, then
for each ordinal ${\alpha}<{\kappa}^+$ there is a 0-dimensional space $X$ with
$ord_l( X)={\kappa}\cdot {\alpha}$;
  (3) if ${\kappa}=2^{\omega}$ or ${\kappa}=\beth_{{\beta}+1}$, where
$cf({\beta})={\omega}$, then for each ordinal ${\alpha}<{\kappa}^+$ there is a
locally compact, locally countable, 0-dimensional space $X$ with $ord_l(
X)={\kappa}\cdot {\alpha}$.
  The union of two left-separated spaces is not necessarily left-separated. We
show, however, that if X is a countably tight space, $X=Y\cup Z, ord_l(Y)$,
$ord_l(Z)<\omega_1 \cdot \omega$, then $X$ is also left-separated and
$ord_l(X)\le ord_l(Y)+ord_l(Z)$. We prove that it is consistent that there is a
first countable, 0-dimensional space X, which is not left-separated, but there
is a c.c.c poset Q such that in the generic extension $V^Q$ we have
$ord_l(X)=\omega_1 \cdot \omega$. However, if $X$ is a topological space and
$Q$ is a c.c.c poset such that in in the generic extension $V^Q$ we have
$ord_l(X)<\omega_1 \cdot \omega$ then X is left-separated even in $V$.


title:
A Comprehensive Analysis of 5G Heterogeneous Cellular Systems operating
  over $\kappa$-$\mu$ Shadowed Fading Channels

abstract:
  Emerging cellular technologies such as those proposed for use in 5G
communications will accommodate a wide range of usage scenarios with diverse
link requirements. This will include the necessity to operate over a versatile
set of wireless channels ranging from indoor to outdoor, from line-of-sight
(LOS) to non-LOS, and from circularly symmetric scattering to environments
which promote the clustering of scattered multipath waves. Unfortunately, many
of the conventional fading models adopted in the literature to develop network
models lack the flexibility to account for such disparate signal propagation
mechanisms. To bridge the gap between theory and practical channels, we
consider $\kappa$-$\mu$ shadowed fading, which contains as special cases, the
majority of the linear fading models proposed in the open literature, including
Rayleigh, Rician, Nakagami-m, Nakagami-q, One-sided Gaussian, $\kappa$-$\mu$,
$\eta$-$\mu$, and Rician shadowed to name but a few. In particular, we apply an
orthogonal expansion to represent the $\kappa$-$\mu$ shadowed fading
distribution as a simplified series expression. Then using the series
expressions with stochastic geometry, we propose an analytic framework to
evaluate the average of an arbitrary function of the SINR over $\kappa$-$\mu$
shadowed fading channels. Using the proposed method, we evaluate the spectral
efficiency, moments of the SINR, bit error probability and outage probability
of a $K$-tier HetNet with $K$ classes of BSs, differing in terms of the
transmit power, BS density, shadowing characteristics and small-scale fading.
Building upon these results, we provide important new insights into the network
performance of these emerging wireless applications while considering a diverse
range of fading conditions and link qualities.


title:
Anomalous diffusion in time-fluctuating non-stationary diffusivity
  landscapes

abstract:
  We investigate the ensemble and time averaged mean squared displacements for
particle diffusion in a simple model for disordered media by assuming that the
local diffusivity is both fluctuating in time and has a deterministic average
growth or decay in time. In this study we compare computer simulations of the
stochastic Langevin equation for this random diffusion process with analytical
results. We explore the regimes of normal Brownian motion as well as anomalous
diffusion in the sub- and superdiffusive regimes. We also consider effects of
the inertial term on the particle motion. The investigation of the resulting
diffusion is performed for unconfined and confined motion.


title: Training a Feedback Loop for Hand Pose Estimation

abstract:
  We propose an entirely data-driven approach to estimating the 3D pose of a
hand given a depth image. We show that we can correct the mistakes made by a
Convolutional Neural Network trained to predict an estimate of the 3D pose by
using a feedback loop. The components of this feedback loop are also Deep
Networks, optimized using training data. They remove the need for fitting a 3D
model to the input data, which requires both a carefully designed fitting
function and algorithm. We show that our approach outperforms state-of-the-art
methods, and is efficient as our implementation runs at over 400 fps on a
single GPU.


title:
Small-angle scattering from the Cantor surface fractal on the plane and
  the Koch snowflake

abstract:
  The small-angle scattering (SAS) from the Cantor surface fractal on the plane
and Koch snowflake is considered. We develop the construction algorithm for the
Koch snowflake, which makes possible the recurrence relation for the scattering
amplitude. The surface fractals can be decomposed into a sum of surface mass
fractals for arbitrary fractal iteration, which enables various approximations
for the scattering intensity. It is shown that for the Cantor fractal, one can
neglect with a good accuracy the correlations between the mass fractal
amplitudes, while for the Koch snowflake, these correlations are important. It
is shown that nevertheless, the correlations can be build in the mass fractal
amplitudes, which explains the decay of the scattering intensity $I(q)\sim
q^{D_{\mathrm{s}}-4}$ with $1 < D_{\mathrm{s}} < 2$ being the fractal dimension
of the perimeter. The curve $I(q)q^{4-D_{\mathrm{s}}}$ is found to be
log-periodic in the fractal region with the period equal to the scaling factor
of the fractal. The log-periodicity arises from the self-similarity of sizes of
basic structural units rather than from correlations between their distances. A
recurrence relation is obtained for the radius of gyration of Koch snowflake,
which is solved in the limit of infinite iterations. The present analysis
allows us to obtain additional information from SAS data, such as the edges of
the fractal regions, the fractal iteration number and the scaling factor.


title: Silicon CMOS architecture for a spin-based quantum computer

abstract:
  Recent advances in quantum error correction (QEC) codes for fault-tolerant
quantum computing \cite{Terhal2015} and physical realizations of high-fidelity
qubits in a broad range of platforms \cite{Kok2007, Brown2011, Barends2014,
Waldherr2014, Dolde2014, Muhonen2014, Veldhorst2014} give promise for the
construction of a quantum computer based on millions of interacting qubits.
However, the classical-quantum interface remains a nascent field of
exploration. Here, we propose an architecture for a silicon-based quantum
computer processor based entirely on complementary metal-oxide-semiconductor
(CMOS) technology, which is the basis for all modern processor chips. We show
how a transistor-based control circuit together with charge-storage electrodes
can be used to operate a dense and scalable two-dimensional qubit system. The
qubits are defined by the spin states of a single electron confined in a
quantum dot, coupled via exchange interactions, controlled using a microwave
cavity, and measured via gate-based dispersive readout \cite{Colless2013}. This
system, based entirely on available technology and existing components, is
compatible with general surface code quantum error correction
\cite{Terhal2015}, enabling large-scale universal quantum computation.


title:
Martingale representation in progressive enlargement by the reference
  filtration of a semimartingale: a note on the multidimensional case

abstract:
  Let X and Y be an m-dimensional F-semimartingale and an n-dimensional
H-semimartingale respectively on the same probability space, both enjoying the
strong predictable representation property. We propose a martingale
representation result under the probability measure P for the square integrable
G-martingales, where G is the union of F and H. As a first application we
identify the biggest possible value of the multiplicity in the sense of Davis
and Varaiya of the union of F1,..., Fd, where, fixed i in (1,...,d), Fi is the
reference filtration of a real martingale Mi, which enjoys the Fi-predictable
representation property. A second application falls into the framework of
credit risk modeling and in particular into the study of the progressive
enlargement of the market filtration by a default time. More precisely, when
the risky asset price is a multidimensional semimartingale enjoying the strong
predictable representation property and the default time satisfies the density
hypothesis, we present a new proof of the analogous of the classical theorem of
Kusuoka.


title: N=4, d=3 Born-Infeld theory in component approach

abstract:
  Using the formalism of nonlinear realizations we construct the component
on-shell action of the N=4,d=3 Born-Infeld theory, which is the action of N=2,
d=3 vector supermultiplet, fixed by invariance with respect to the additional
spontaneously broken N=2, d=3 supersymmetry. Our construction shows that
dealing with the systems with partial breaking of supersymmetry with vector
fields in the multiplet, it is preferrable to use their formulation in terms of
fermionic superfields only.


title:
Trace formulae for Schr\"odinger operators with complex-valued
  potentials on cubic lattices

abstract:
  We consider Schr\"odinger operators with complex decaying potentials on the
lattice. Using some classical results from Complex Analysis we obtain some
trace formulae and using them estimate globally all zeros of the Fredholm
determinant in terms of the potential.


title:
Continuous matrix product states with periodic boundary conditions and
  an application to atomtronics

abstract:
  We introduce a time evolution algorithm for one-dimensional quantum field
theories with periodic boundary conditions. This is done by applying the
Dirac-Frenkel time-dependent variational principle to the set of translational
invariant continuous matrix product states with periodic boundary conditions.
Moreover, the ansatz is accompanied with additional boundary degrees of freedom
to study quantum impurity problems. The algorithm allows for a cutoff in the
spectrum of the transfer matrix and thus has an efficient computational
scaling. In particular we study the prototypical example of an atomtronic
system - an interacting Bose gas rotating in a ring shaped trap in the presence
of a localised barrier potential.


title: Regimes of turbulence without an energy cascade

abstract:
  Experiments and numerical simulations of turbulent $^4$He and $^3$He-B have
established that, at hydrodynamic length scales larger than the average
distance between quantum vortices, the energy spectrum obeys the same 5/3
Kolmogorov law which is observed in the homogeneous isotropic turbulence of
ordinary fluids. The importance of the 5/3 law is that it points to the
existence of a Richardson energy cascade from large eddies to small eddies.
However, there is also evidence of quantum turbulent regimes without Kolmogorov
scaling. This raises the important questions of why, in such regimes, the
Kolmogorov spectrum fails to form, what is the physical nature of turbulence
without energy cascade, and whether hydrodynamical models can account for the
unusual behaviour of turbulent superfluid helium. In this work we describe
simple physical mechanisms which prevent the formation of Kolmogorov scaling in
the thermal counterflow, and analyze the conditions necessary for emergence of
quasiclassical regime in quantum turbulence generated by injection of vortex
rings at low temperatures. Our models justify the hydrodynamical description of
quantum turbulence and shed light into an unexpected regime of vortex dynamics.


title:
Star formation history of And XVIII: a dwarf spheroidal galaxy in
  isolation

abstract:
  We present a photometric study of the Andromeda XVIII dwarf spheroidal galaxy
associated with M31, and situated well outside of the virial radius of the M31
halo. The galaxy was resolved into stars with Hubble Space Telescope/Advanced
Camera for Surveys revealing the old red giant branch and red clump. With the
new observational data we determined the Andromeda XVIII distance to be D =
1.33+-0.08 Mpc using the tip of red giant branch method. Thus, the dwarf is
situated at the distance of 579 kpc from M31. We model the star formation
history of Andromeda XVIII from the stellar photometry and Padova theoretical
stellar isochrones. An ancient burst of star formation occurred 12-14 Gyr ago.
There is no sign of recent/ongoing star formation in the last 1.5 Gyr. The mass
fractions of the ancient and intermediate age stars are 34 and 66 per cent,
respectively, and the total stellar mass is 4.2x10^6 Msun. It is probable that
the galaxy has not experienced an interaction with M31 in the past. We also
discuss star formation processes of dSphs KKR 25, KKs 03, as well as dTr KK
258. Their star formation histories were uniformly measured by us from HST/ACS
observations. All the galaxies are situated well beyond the Local Group and the
two dSphs KKR 25 and KKs 03 are extremely isolated. Evidently, the evolution of
these objects has proceeded without influence of neighbours.


title: Some loose ends on unbounded order convergence

abstract:
  The notion of almost everywhere convergence has been generalized to vector
lattices as unbounded order convergence, which proves a very useful tool in the
theory of vector and Banach lattices. In this short note, we establish some new
results on unbounded order convergence that tie up some loose ends. In
particular, we show that every norm bounded positive increasing net in an order
continuous Banach lattice is uo-Cauchy and that every uo-Cauchy net in an order
continuous Banach lattice has a uo-limit in the universal completion.


title: Locally Compact Stone Duality

abstract:
  We prove a number of dualities between posets and (pseudo)bases of open sets
in locally compact Hausdorff spaces. In particular, we show that
  (1) Relatively compact basic sublattices are finitely axiomatizable.
  (2) Relatively compact basic subsemilattices are those omitting certain
types.
  (3) Compact clopen pseudobasic posets are characterized by separativity.
  We also show how to obtain the tight spectrum of a poset as the Stone space
of a generalized Boolean algebra that is universal for tight representations.


title: Type checking through unification

abstract:
  In this paper we describe how to leverage higher-order unification to type
check a dependently typed language with meta-variables. The literature usually
presents the unification algorithm as a standalone component, however the need
to check definitional equality of terms while type checking gives rise to a
tight interplay between type checking and unification. This interplay is a
major source of complexity in the type-checking algorithm for existing
dependently typed programming languages. We propose an algorithm that encodes a
type-checking problem entirely in the form of unification constraints, reducing
the complexity of the type-checking code by taking advantage of higher order
unification, which is already part of the implementation of many dependently
typed languages.


title:
Accumulation Rate of Bound States of Dipoles Generated by Point Charges
  in Strained Graphene

abstract:
  We consider strained graphene, modelled by the two-dimensional massive Dirac
operator, with potentials corresponding to charge distributions with vanishing
total charge, non-vanishing dipole moment and finitely many point charges of
subcritical coupling constants located in the graphene sheet. We show that the
bound state energies accumulate exponentially fast at the edges of the spectral
gap by determining the leading order of the accumulation rate.


title: Roundness of grains in cellular microstructures

abstract:
  Many physical systems are composed of polyhedral cells of varying sizes and
shapes. These structures are simple in the sense that no more than three faces
meet at an edge and no more than four edges meet at a vertex. This means that
individual cells can usually be considered as simple, three-dimensional
polyhedra. This paper is concerned with determining the distribution of
combinatorial types of such polyhedral cells. We introduce the terms
\emph{fundamental} and \emph{vertex-truncated} types and apply these concepts
to the grain growth microstructure as a testing ground. For these
microstructures we demonstrate that most grains are of particular fundamental
types, whereas the frequency of vertex-truncated types decreases exponentially
with the number of truncations. This can be explained by the evolutionary
process through which grain growth structures are formed, and in which
energetically unfavorable surfaces are quickly eliminated. Furthermore, we
observe that these grain types are `round' in a combinatorial sense: there are
no `short' separating cycles that partition the polyhedra into two parts of
similar sizes. A particular microstructure derived from the Poisson--Voronoi
initial condition is identified as containing an unusually large proportion of
round grains. This Round microstructure has an average of $14.036$ faces per
grain, and is conjectured to be more resistant to topological change than the
steady-state grain growth microstructure.


title:
Light-mediated cascaded locking of multiple nano-optomechanical
  oscillators

abstract:
  Collective phenomena emerging from non-linear interactions between multiple
oscillators, such as synchronization and frequency locking, find applications
in a wide variety of fields. Optomechanical resonators, which are intrinsically
non-linear, combine the scientific assets of mechanical devices with the
possibility of long distance controlled interactions enabled by travelling
light. Here we demonstrate light-mediated frequency locking of three distant
nano-optomechanical oscillators positioned in a cascaded configuration. The
oscillators, integrated on a chip along a coupling waveguide, are optically
driven with a single laser and oscillate at gigahertz frequency. Despite an
initial frequency disorder of hundreds of kilohertz, the guided light locks
them all with a clear transition in the optical output. The experimental
results are described by Langevin equations, paving the way to scalable
cascaded optomechanical configurations.


title: A deep representation for depth images from synthetic data

abstract:
  Convolutional Neural Networks (CNNs) trained on large scale RGB databases
have become the secret sauce in the majority of recent approaches for object
categorization from RGB-D data. Thanks to colorization techniques, these
methods exploit the filters learned from 2D images to extract meaningful
representations in 2.5D. Still, the perceptual signature of these two kind of
images is very different, with the first usually strongly characterized by
textures, and the second mostly by silhouettes of objects. Ideally, one would
like to have two CNNs, one for RGB and one for depth, each trained on a
suitable data collection, able to capture the perceptual properties of each
channel for the task at hand. This has not been possible so far, due to the
lack of a suitable depth database. This paper addresses this issue, proposing
to opt for synthetically generated images rather than collecting by hand a 2.5D
large scale database. While being clearly a proxy for real data, synthetic
images allow to trade quality for quantity, making it possible to generate a
virtually infinite amount of data. We show that the filters learned from such
data collection, using the very same architecture typically used on visual
data, learns very different filters, resulting in depth features (a) able to
better characterize the different facets of depth images, and (b) complementary
with respect to those derived from CNNs pre-trained on 2D datasets. Experiments
on two publicly available databases show the power of our approach.


title: Magnetic BV functions and the Bourgain-Brezis-Mironescu formula

abstract:
  We prove a general magnetic Bourgain-Brezis-Mironescu formula. In particular,
after developing a theory of magnetic bounded variation functions, we prove the
validity of the formula in this class.


title:
Electronic transport modulation on few-layers suspended MoS$_2$ under
  strain

abstract:
  The production of new sensors, transducers and electronic components can
benefit from the possibility to alter the electronic transport of
metal-semicondutor-metal (MSM) devices. 2D materials are extremely appealing
for those new technologies. This can determined by several phenomena as
piezoelectric effect, piezoresistive effect and modulation of Schottky barrier.
In particular, MoS$_2$, among other Transition Metal Dichalcogenides (TMDs), is
predicted to show a transition from semiconductor to metal under strain. In
this article we present measurements on the modulation of electronic transport
on few layer MoS$_2$ suspended ribbons under uniaxial tensile strain.
Experimentally observed changes in the two terminal IV curves can be explained
in terms of band gap closing in the semiconductor. A maximum gauge factor of
240 is achieved for a 3-layer ribbon. We also report on the fabrication process
that allows to apply high strains to suspended MoS$_2$ ribbons, paving the way
to future studies on the effect of strain in 2D materials.


title:
Modelling observed decay-less oscillations as resonantly enhanced
  Kelvin-Helmholtz vortices from transverse MHD waves and their seismological
  application

abstract:
  In the highly structured solar corona, resonant absorption is an unavoidable
mechanism of energy transfer from global transverse MHD waves to local
azimuthal Alfv\'en waves. Due to its localised nature, a direct detection of
this mechanism is extremely difficult. Yet, it is the leading theory explaining
the observed fast damping of the global transverse waves. However, at odds with
this theoretical prediction, recent observations indicate that in the low
amplitude regime such transverse MHD waves can also appear decay-less, a yet
unsolved phenomenon. Recent numerical work has shown that Kelvin-Helmholtz
instabilities (KHI) often accompany transverse MHD waves. In this work, we
combine 3D MHD simulations and forward modelling to show that for currently
achieved spatial resolution and observed small amplitudes, an apparent
decay-less oscillation is obtained. This effect results from the combination of
periodic brightenings produced by the KHI and the coherent motion of the KHI
vortices amplified by resonant absorption. Such effect is especially clear in
emission lines forming at temperatures that capture the boundary dynamics
rather than the core, and reflects the low damping character of the local
azimuthal Alfv\'en waves resonantly coupled to the kink mode. Due to phase
mixing, the detected period can vary depending on the emission line, with those
sensitive to the boundary having shorter periods than those sensitive to the
loop core. This allows to estimate the density contrast at the boundary.


title: Holographic superconductor with momentum relaxation and Weyl correction

abstract:
  We construct a holographic model with Weyl corrections in five dimensional
spacetime. In particular, we introduce a coupling term between the axion fields
and the Maxwell field such that the momentum is relaxed even in the probe limit
in this model. We investigate the Drude behavior of the optical conductivity in
low frequency region. It is interesting to find that the incoherent part of the
conductivity is suppressed with the increase of the axion parameter $k/T$,
which is in contrast to other holographic axionic models at finite density.
Furthermore, we study the superconductivity associated with the condensation of
a complex scalar field and evaluate the critical temperature for condensation
in both analytical and numerical manner. It turns out that the critical
temperature decreases with $\tilde{k}$,indicating that the condensation becomes
harder in the presence of the axions, while it increases with Weyl parameter
$\gamma$. We also discuss the change of the gap in optical conductivity with
coupling parameters. Finally, we evaluate the charge density of the superfluid
in zero temperature limit, and find that it exhibits a linear relation with
$\tilde{\sigma}_{DC}(\tilde{T_c})\tilde{T_c}$, such that a modified version of
Homes' law is testified.


title: Jolie Community on the Rise

abstract:
  Jolie is a programming language that follows the microservices paradigm. As
an open source project, it has built a community of developers worldwide - both
in the industry as well as in academia - taken care of the development,
continuously improved its usability, and therefore broadened the adoption. In
this paper, we present some of the most recent results and work in progress
that has been made within our research team.


title: ZZ production in gluon fusion at NLO matched to parton-shower

abstract:
  We present a calculation of the next-to-leading order (NLO) QCD corrections
to the hadroproduction process $gg\to ZZ \to e^+e^- \mu^+ \mu^-$, matched to
the parton shower in the POWHEG framework. We take advantage of the POWHEG BOX
tool for the implementation and rely on PYTHIA 8 for the showering and
hadronization stages. We fully include $\gamma^*/Z$ interference effects, while
also covering the single-resonant region. For this phenomenological study we
focus on four lepton production as a signal process, neglecting all quark mass
effects as well as the Higgs-mediated contributions, which are known to be
subdominant in this case. We provide predictions from our simulations for the
13 TeV LHC Run II setup, including realistic experimental cuts.


title: Skin Normal Force Calibration Using Vacuum Bags

abstract:
  The paper presents a proof of concept to calibrate iCub's skin using vacuum
bags. The method's main idea consists in inserting the skin in a vacuum bag,
and then decreasing the pressure in the bag to create a uniform pressure
distribution on the skin surface. Acquisition and data processing of the bag
pressure and sensors' measured capacitance allow us to characterize the
relationship between the pressure and the measured capacitance of each sensor.
After calibration, integration of the pressure distribution over the skin
geometry provides us with the net normal force applied to the skin. Experiments
are conducted using the forearm skin of the iCub humanoid robot, and validation
results indicate acceptable average errors in force prediction.


title: Twisted spacetime in Einstein gravity

abstract:
  We find a vacuum stationary twisted solution in four-dimensional Einstein
gravity. Its frame dragging angular velocities are antisymmetric with respect
to the equatorial plane. It possesses a symmetry of joint inversion of time and
parity with respect to the equatorial plane. Its Arnowitt-Deser-Misner (ADM)
mass and angular momentum are zero. It is curved but regular all over the
manifold. Its Komar mass and Komar angular momentum are also zero. Its infinite
red-shift surface coincides with its event horizon, since the event horizon
does not rotate. Furthermore we extend this solution to the massive case, and
find some similar properties. This solution is a stationary axisymmetric
solution, but not Kerr. It explicitly proves that pure Einstein gravity permits
different rotational mode other than Kerr. Our results demonstrate that the
Einstein theory may have much more rich structures than what we ever imagine.


title:
Photoionisation of Cl$^+$ from the $3s^23p^4\;^3P_{2,1,0}$ and
  the$3s^23p^4\;^1D_2, ^1S_0$ states in the energy range 19 - 28 eV

abstract:
  Absolute photoionisation cross sections for the Cl$^+$ ion in its ground and
the metastable states; $3s^2 3p^4\; ^3P_{2,1,0}$, and $3s^2 3p^4\; ^1D_2,\;
^1S_0$, were measured recently at the Advanced Light Source ALS) at Lawrence
Berkeley National Laboratory using the merged beams photon-ion technique at an
photon energy resolution of 15 meV in the energy range 19 -- 28 eV. These
measurements are compared with large-scale Dirac Coulomb {\it R}-matrix
calculations in the same energy range. Photoionisation of this sulphur-like
chlorine ion is characterized by multiple Rydberg series of autoionizing
resonances superimposed on a direct photoionisation continuum. A wealth of
resonance features observed in the experimental spectra are spectroscopically
assigned and their resonance parameters tabulated and compared with the recent
measurements. Metastable fractions in the parent ion beam are determined from
the present study. Theoretical resonance energies and quantum defects of the
prominent Rydberg series $3s^2 3p^3 nd$, identified in the spectra as
$3p\rightarrow nd$ transitions are compared with the available measurements
made on this element. Weaker Rydberg series $3s^2 3p^3 ns$, identified as $3p
\rightarrow ns$ transitions and window resonances $3s3p^4 (^4P)np$ features,
due to $3s \rightarrow np$ transitions are also found in the spectra.


title: Composing decoherence functionals

abstract:
  Quantum Measure Theory (QMT) is a generalization of quantum theory where
physical predictions are computed from a matrix known as \emph{decoherence
functional} (DF). Previous works have noted that, in its original formulation,
QMT exhibits a problem with composability, since the composition of two
decoherence functionals is, in general, not a valid decoherence functional.
This does not occur when the DFs in question happen to be positive semidefinite
(a condition known as strong positivity). In this paper, we study the concept
of composability of DFs and its consequences for QMT. Firstly, we show that the
problem of composability is much deeper than originally envisaged, since, for
any $n$, there exists a DF that can co-exist with $n-1$ copies of itself, but
not with $n$. Secondly, we prove that the set of strongly positive DFs cannot
be enlarged while remaining closed under composition. Furthermore, any closed
set of DFs containing all quantum DFs can only contain strongly positive DFs.


title: Distinguishing Galois representations by their normalized traces

abstract:
  Suppose \( \rho_1 \) and \( \rho_2 \) are two pure Galois representations of
the absolute Galois group of a number field $K$ of weights \( k_1 \) and \( k_2
\) respectively, having equal normalized Frobenius traces \(
Tr(\rho_1(\sigma_v)) /Nv^{k_1/2}\) and \( Tr(\rho_2(\sigma_v)) /Nv^{k_2/2}\) at
a set of primes \( v\) of $K$ with positive upper density. Assume further that
the algebraic monodromy group of $\rho_1$ is connected and the repesentation is
absolutely irreducible. We prove that \( \rho_1 \) and \( \rho_2 \) are twists
of each other by power of a Tate twist times a character of finite order.
  We apply this to modular forms and deduce a result proved by Murty and
Pujahari.


title:
Efficient simulation for dependent rare events with applications to
  extremes

abstract:
  We consider the general problem of estimating probabilities which arise as a
union of dependent events. We propose a flexible series of estimators for such
probabilities, and describe variance reduction schemes applied to the proposed
estimators. We derive efficiency results of the estimators in rare-event
settings, in particular those associated with extremes. Finally, we examine the
performance of our estimators in a numerical example.


title: Revisiting 802.11 Rate Adaptation from Energy Consumption's Perspective

abstract:
  Rate adaptation in 802.11 WLANs has received a lot of attention from the
research community, with most of the proposals aiming at maximising throughput
based on network conditions. Considering energy consumption, an implicit
assumption is that optimality in throughput implies optimality in energy
efficiency, but this assumption has been recently put into question. In this
paper, we address via analysis and experimentation the relation between
throughput performance and energy efficiency in multi-rate 802.11 scenarios. We
demonstrate the trade-off between these performance figures, confirming that
they may not be simultaneously optimised, and analyse their sensitivity towards
the energy consumption parameters of the device. Our results provide the means
to design novel rate adaptation schemes that takes energy consumption into
account.


title:
Pair Production, Vacuum Polarization and Anomaly in (A)dS and Charged
  Black Holes

abstract:
  We explore the connection between the distribution of particles spontaneously
produced from an electric field or black hole and the vacuum persistence, twice
the imaginary part of the one-loop effective action. Employing the
reconstruction conjecture, we find the effective action for the Bose-Einstein
or Fermi-Dirac distribution. The Schwinger effect in ${\rm AdS}_2$ is computed
via the phase-integral method in the static coordinates. The Hawking radiation
and Schwinger effect of a charged black hole is rederived and interpreted via
the phase-integral. Finally, we discuss the relation between the vacuum
persistence and the trace or gravitational anomalies.


title: On the Complexity of Bounded Context Switching

abstract:
  Bounded context switching (BCS) is an under-approximate method for finding
violations to safety properties in shared memory concurrent programs.
Technically, BCS is a reachability problem that is known to be NP-complete. Our
contribution is a parameterized analysis of BCS.
  The first result is an algorithm that solves BCS when parameterized by the
number of context switches (cs) and the size of the memory (m) in
O*(m^(cs)2^(cs)). This is achieved by creating instances of the easier problem
Shuff which we solve via fast subset convolution. We also present a lower bound
for BCS of the form m^o(cs / log(cs)), based on the exponential time
hypothesis. Interestingly, closing the gap means settling a conjecture that has
been open since FOCS'07. Further, we prove that BCS admits no polynomial
kernel.
  Next, we introduce a measure, called scheduling dimension, that captures the
complexity of schedules. We study BCS parameterized by the scheduling dimension
(sdim) and show that it can be solved in O*((2m)^(4sdim)4^t)$, where t is the
number of threads. We consider variants of the problem for which we obtain
(matching) upper and lower bounds.


title:
Composition operators on the discrete analogue of generalized Hardy
  space on homogenous trees

abstract:
  In this paper, we study the basic properties such as boundedness and
compactness of composition operators on discrete analogue of generalized Hardy
space defined on a homogeneous rooted tree. Also, we compute the operator norm
of composition operator when inducing symbol is automorphism of a homogenous
tree.


title: Cosmology with the CMB temperature-polarization correlation

abstract:
  We demonstrate that the cosmic microwave background (CMB)
temperature-polarization cross-correlation provides accurate and robust
constraints on cosmological parameters. We compare them with the results from
temperature or polarization and investigate the impact of foregrounds, cosmic
variance, and instrumental noise. This analysis makes use of the Planck
high-multipole HiLLiPOP likelihood based on angular power spectra, which takes
into account systematics from the instrument and foreground residuals directly
modelled using Planck measurements. The temperature-polarization correlation
(TE) spectrum is less contaminated by astrophysical emissions than the
temperature power spectrum (TT), allowing constraints that are less sensitive
to foreground uncertainties to be derived. For {\Lambda}CDM parameters, TE
gives very competitive results compared to TT. For basic {\Lambda}CDM model
extensions (such as AL, {\Sigma}m{\nu}, or Neff ), it is still limited by the
instrumental noise level in the polarization maps.


title:
Experimental nonlocality-based network diagnostics of mutipartite
  entangled states

abstract:
  Quantum networks of growing complexity play a key role as resources for
quantum computation; the ability to identify the quality of their internal
correlations will play a crucial role in addressing the buiding stage of such
states. We introduce a novel diagnostic scheme for multipartite networks of
entangled particles, aimed at assessing the quality of the gates used for the
engineering of their state. Using the information gathered from a set of
suitably chosen multiparticle Bell tests, we identify conditions bounding the
quality of the entangled bonds among the elements of a register. We demonstrate
the effectiveness, flexibility, and diagnostic power of the proposed
methodology by characterizing a quantum resource engineered combining
two-photon hyperentanglement and photonic-chip technology. Our approach is
feasible for medium-sized networks due to the intrinsically modular nature of
cluster states, and paves the way to section-by-section analysis of large
photonics resources.


title: Two-jet astrosphere model: effect of azimuthal magnetic field

abstract:
  Opher et al. (2015), Drake et al. (2015) have shown that the heliospheric
magnetic field results in formation of two-jet structure of the solar wind flow
in the inner heliosheath, i.e. in the subsonic region between the heliospheric
termination shock and the heliopause. In this scenario the heliopause has a
tube-like topology as compared with a sheet-like topology in the most models of
the global heliosphere (e.g. Izmodenov and Alexashov, 2015). In this paper we
explore the two-jet scenario for a simplified astrosphere in which 1) the star
is at rest with respect to the circumstellar medium, 2) radial magnetic field
is neglected as compared with azimuthal component, 3) the stellar wind outflow
is assumed to be hypersonic (both the Mach number and the Alfv\'enic Mach
number are much greater than unity at the inflow boundary). We have shown that
the problem can be formulated in dimensionless form, in which the solution
depends only on one dimensionless parameter epsilon that is reciprocal of the
Alfv\'enic Mach number at the inflow boundary. This parameter is proportional
to stellar magnetic field. We present the numerical solution of the problem for
various values of epsilon. Three first integrals of the governing ideal MHD
equations are presented, and we make use of them in order to get the plasma
distribution in the jets. Simple relations between distances to the termination
shock, astropause and the size of the jet are established. These relations
allow us to determine the stellar magnetic field from the geometrical pattern
of the jet-like astrosphere.


title: Inverse curvature flow in anti-de Sitter-Schwarzschild manifold

abstract:
  In this paper, we consider the inverse hessian quotient curvature flow with
star-shaped initial hypersurface in anti-de Sitter-Schwarzschild manifold. We
prove that the solution exists for all time, and the second fundamental form
converges to identity exponentially fast.


title: Deceleration of a supersonic beam of SrF molecules to 120 m/s

abstract:
  We report on the deceleration of a beam of SrF molecules from 290 to 120~m/s.
Following supersonic expansion, the molecules in the $X^2\Sigma$ ($v=0$, $N=1$)
low-field seeking states are trapped by the moving potential wells of a
traveling-wave Stark decelerator. With a deceleration strength of 9.6 km/s$^2$
we have demonstrated the removal of 85 % of the initial kinetic energy in a 4
meter long modular decelerator. The absolute amount of kinetic energy removed
is a factor 1.5 higher compared to previous Stark deceleration experiments. The
demonstrated decelerator provides a novel tool for the creation of highly
collimated and slow beams of heavy diatomic molecules, which serve as a good
starting point for high-precision tests of fundamental physics.


title:
The potential of discrimination methods in a high pressure xenon TPC for
  the search of the neutrinoless double-beta decay of Xe-136

abstract:
  In the search for the neutrinoless double beta decay of $^{136}$Xe, a high
pressure xenon time projection chamber (HPXe-TPC) has two advantages over
liquid xenon TPCs: a better energy resolution and the access to topological
features, which may provide extra discrimination from background events. The
PandaX-III experiment has recently proposed a 200 kg HPXe-TPC based on
Micromegas readout planes, to be located at the Jinping Underground Laboratory
in China. Its detection concept is based on two results obtained within the
T-REX project: Micromegas readouts can be built with extremely low levels of
radioactivity; and the operation in xenon-trimethylamine at 10 bar in realistic
experimental conditions has proven an energy resolution of 3% FWHM at the
region of interest. In this work, two discrimination methods are applied to
simulated signal and background data in a generic 200 kg HPXe-TPC, based on two
well-known algorithms of graph theory: the identification of connections and
the search for the longest path. Rejection factors greater than 100 are
obtained for small pixel sizes and a signal efficiency of 40%. Moreover, a new
observable (the blob charge density) rejects better surface contaminations,
which makes the use of a trigger signal ($T_0$) not imperative in this
experiment.


title: Time decay for solutions to the Stokes equations with drift

abstract:
  In this note, we study the behaviour of Lebesgue norms $\|v(\cdot,t)\|_p$ of
solutions $v$ to the Cauchy problem for the Stokes system with drift $u$, which
is supposed to be a divergence free smooth vector valued function satisfying a
scale invariant condition.


title:
The role of sample height in the stacking diagram of colloidal mixtures
  under gravity

abstract:
  Bulk phase separation is responsible for the occurrence of stacks of
different layers in sedimentation of colloidal mixtures. A recently proposed
theory (de las Heras and Schmidt 2013 Soft Matter 9 8636) establishes a unique
connection between the bulk phase behaviour and
sedimentation-diffusion-equilibrium. The theory constructs a stacking diagram
of all possible sequences of stacks under gravity in the limit of very high
(infinite) sample heights. Here, we study the stacking diagrams of colloidal
mixtures at finite sample height, h. We demonstrate that h plays a vital role
in sedimentation-diffusion-equilibrium of colloidal mixtures. The region of the
stacking diagram occupied by a given sequence of stacks depends on h. Hence,
two samples with different heights but identical colloidal concentrations can
develop different stacking sequences. In addition, the stacking diagrams for
different heights can be qualitatively different since some stacking sequences
occur only in a given interval of sample heights. We use the theory to
investigate the stacking diagrams of both model bulk systems and mixtures of
patchy particles that differ either by the number or by the types of patches.


title: Exclusive $J/\psi$ process tamed to probe the low $x$ gluon

abstract:
  We address the question as to whether data for J/\psi mesons produced
exclusively in the forward direction at the LHC can be used in global parton
analyses (based on collinear factorization) to pin down the low x gluon PDF. We
show that it may be possible to overcome the problems that (i) the process is
described by a skewed or Generalized Parton Distribution (GPD), (ii) it is very
sensitive to the choice of factorization scale and (iii) there is bad LO,
NLO,... perturbative stability to the predictions. However, we start by briefly
explaining how the alternative k_T factorization approach has been used to
describe the process.


title: Graphs, Ideal Flow, and the Transportation Network

abstract:
  This lecture discusses the mathematical relationship between network
structure and network utilization of transportation network. Network structure
means the graph itself. Network utilization represent the aggregation of
trajectories of agents in using the network graph. I show the similarity and
relationship between the structural pattern of the network and network
utilization.


title:
Calabi-Yau compactifications of toric Landau-Ginzburg models for smooth
  Fano threefolds

abstract:
  We prove that smooth Fano threefolds have toric Landau--Ginzburg models. More
precise, we prove that their Landau--Ginzburg models, presented as Laurent
polynomials, admit compactifications to families of K3 surfaces, and we
describe their fibers over infinity. We also give an explicit construction of
Landau--Ginzburg models for del Pezzo surfaces and any divisors on them.


title: Infinite-dimensional input-to-state stability and Orlicz spaces

abstract:
  In this work, the relation between input-to-state stability and integral
input-to-state stability is studied for linear infinite-dimensional systems
with an unbounded control operator. Although a special focus is laid on the
case $L^{\infty}$, general function spaces are considered for the inputs. We
show that integral input-to-state stability can be characterized in terms of
input-to-state stability with respect to Orlicz spaces. Since we consider
linear systems, the results can also be formulated in terms of admissibility.
For parabolic diagonal systems with scalar inputs, both stability notions with
respect to $L^\infty$ are equivalent.


title:
Quantum Vorticity at positive temperature for spin systems with
  continuous symmetry

abstract:
  We propose a definition of vorticity at inverse temperature $\beta$ for Gibbs
states in quantum XY or Heisenberg spin systems on the lattice by testing
$\exp[-\beta H]$ on a complete set of observables ("one-point functions").
Imposing a compression of Pauli matrices at the boudary, which stands for the
classical environment, we perform some numerical simulations on finite lattices
in case of XY model, which exhibit usual vortex patterns.


title:
Rectified binaural ratio: A complex T-distributed feature for robust
  sound localization

abstract:
  Most existing methods in binaural sound source localization rely on some kind
of aggregation of phase-and level-difference cues in the time-frequency plane.
While different ag-gregation schemes exist, they are often heuristic and suffer
in adverse noise conditions. In this paper, we introduce the rectified binaural
ratio as a new feature for sound source local-ization. We show that for
Gaussian-process point source signals corrupted by stationary Gaussian noise,
this ratio follows a complex t-distribution with explicit parameters. This new
formulation provides a principled and statistically sound way to aggregate
binaural features in the presence of noise. We subsequently derive two simple
and efficient methods for robust relative transfer function and time-delay
estimation. Experiments on heavily corrupted simulated and speech signals
demonstrate the robustness of the proposed scheme.


title:
Phase Unmixing : Multichannel Source Separation with Magnitude
  Constraints

abstract:
  We consider the problem of estimating the phases of K mixed complex signals
from a multichannel observation, when the mixing matrix and signal magnitudes
are known. This problem can be cast as a non-convex quadratically constrained
quadratic program which is known to be NP-hard in general. We propose three
approaches to tackle it: a heuristic method, an alternate minimization method,
and a convex relaxation into a semi-definite program. The last two approaches
are showed to outperform the oracle multichannel Wiener filter in
under-determined informed source separation tasks, using simulated and speech
signals. The convex relaxation approach yields best results, including the
potential for exact source separation in under-determined settings.


title: Gauged Supergravities

abstract:
  We give a general review of extended supergravities and their gauging using
the duality-covariant embedding tensor formalism. Although the focus is on
four-dimensional theories, an overview of the gauging procedure and the related
tensor hierarchy in the higher-dimensional models is given. The relation of
gauged supergravities to flux compactifications is discussed and examples are
worked out in detail.


title: Independent sets in the union of two Hamiltonian cycles

abstract:
  Motivated by a question on the maximal number of vertex disjoint Schrijver
graphs in the Kneser graph, we investigate the following function, denoted by
$f(n,k)$: the maximal number of Hamiltonian cycles on an $n$ element set, such
that no two cycles share a common independent set of size more than $k$. We
shall mainly be interested in the behavior of $f(n,k)$ when $k$ is a linear
function of $n$, namely $k=cn$. We show a threshold phenomenon: there exists a
constant $c_t$ such that for $c<c_t$, $f(n,cn)$ is bounded by a constant
depending only on $c$ and not on $n$, and for $c_t <c$, $f(n,cn)$ is
exponentially large in $n ~(n \to \infty)$. We prove that $0.26 < c_t < 0.36$,
but the exact value of $c_t$ is not determined. For the lower bound we prove a
technical lemma, which for graphs that are the union of two Hamiltonian cycles
establishes a relation between the independence number and the number of $K_4$
subgraphs. A corollary of this lemma is that if a graph $G$ on $n>12$ vertices
is the union of two Hamiltonian cycles and $\alpha(G)=n/4$, then $V(G)$ can be
covered by vertex-disjoint $K_4$ subgraphs.


title:
Hearing in a shoe-box : binaural source position and wall absorption
  estimation using virtually supervised learning

abstract:
  This paper introduces a new framework for supervised sound source
localization referred to as virtually-supervised learning. An acoustic shoe-box
room simulator is used to generate a large number of binaural single-source
audio scenes. These scenes are used to build a dataset of spatial binaural
features annotated with acoustic properties such as the 3D source position and
the walls' absorption coefficients. A probabilistic high- to low-dimensional
regression framework is used to learn a mapping from these features to the
acoustic properties. Results indicate that this mapping successfully estimates
the azimuth and elevation of new sources, but also their range and even the
walls' absorption coefficients solely based on binaural signals. Results also
reveal that incorporating random-diffusion effects in the data significantly
improves the estimation of all parameters.


title: Characterization of experts in crowdsourcing platforms

abstract:
  Crowdsourcing platforms enable to propose simple human intelligence tasks to
a large number of participants who realise these tasks. The workers often
receive a small amount of money or the platforms include some other incentive
mechanisms, for example they can increase the workers reputation score, if they
complete the tasks correctly. We address the problem of identifying experts
among participants, that is, workers, who tend to answer the questions
correctly. Knowing who are the reliable workers could improve the quality of
knowledge one can extract from responses. As opposed to other works in the
literature, we assume that participants can give partial or incomplete
responses, in case they are not sure that their answers are correct. We model
such partial or incomplete responses with the help of belief functions, and we
derive a measure that characterizes the expertise level of each participant.
This measure is based on precise and exactitude degrees that represent two
parts of the expertise level. The precision degree reflects the reliability
level of the participants and the exactitude degree reflects the knowledge
level of the participants. We also analyze our model through simulation and
demonstrate that our richer model can lead to more reliable identification of
experts.


title: Molecular gas kinematics of the CMZ: Great oaks from little acorns grow

abstract:
  The central molecular zone (CMZ) hosts some of the most massive and dense
molecular clouds and star clusters in the Galaxy, offering an important window
into star formation under extreme conditions. Star formation in this extreme
environment may be closely linked to the 3-D distribution and orbital dynamics
of the gas. Here I discuss how our new, accurate description of the $\{l,b,v\}$
structure of the CMZ is helping to constrain its 3-D geometry. I also present
the discovery of a highly-regular, corrugated velocity field located just
upstream from the dust ridge molecular clouds (which include G0.253+0.016 and
Sgr B2). The extremes in this velocity field correlate with a series of massive
($\sim10^{4}$ M$_{\odot}$) cloud condensations. The corrugation wavelength
($\sim23$ pc) and cloud separation ($\sim8$ pc) closely agree with the
predicted Toomre ($\sim17$ pc) and Jeans ($\sim6$ pc) lengths, respectively. I
conclude that gravitational instabilities are driving the formation of
molecular clouds within the Galactic Centre gas stream. Furthermore, I suggest
that these seeds are the historical analogues of the dust ridge molecular
clouds - possible progenitors of some of the most massive and dense molecular
clouds in the Galaxy. If our current best understanding for the 3-D geometry of
this system is confirmed, these clouds may pinpoint the beginning of an
evolutionary sequence that can be followed, in time, from cloud condensation to
star formation.


title: Realistic quantum critical point in one-dimensional two-impurity models

abstract:
  We show that the two-impurity Anderson model exhibits an additional quantum
critical point at infinitely many specific distances between both impurities
for an inversion symmetric one-dimensional dispersion. Unlike the quantum
critical point previously established, it is robust against particle-hole or
parity symmetry breaking. The quantum critical point separates a spin doublet
from a spin singlet ground state and is, therefore, protected. A finite
single-particle tunneling $t$ or an applied uniform gate voltage will drive the
system across the quantum critical point. The discriminative magnetic
properties of the different phases cause a jump in the spectral functions at
low temperature, which might be useful for future spintronics devices. A local
parity conservation will prevent the spin-spin correlation function from
decaying to its equilibrium value after spin manipulations.


title: Reactions with a 10Be beam to study the one-neutron halo nucleus 11Be

abstract:
  Halo nuclei are excellent examples of few-body systems consisting of a core
and weakly-bound halo nucleons. Where there is only one nucleon in the halo, as
in 11Be, the many-body problem can be reduced to a two-body problem. The
contribution of the 1s1/2 orbital to the ground state configuration in 11Be,
characterized by the spectroscopic factor, S, has been extracted from direct
reaction data by many groups over the past five decades with discrepant
results. An experiment was performed at the Holifield Radioactive Ion Beam
Facility using a 10Be primary beam at four different energies with the goal of
resolving the discrepancy through a consistent analysis of elastic, inelastic,
and transfer channels. Faddeev-type calculations, released after the
publication of the experimental results, show that dynamic core excitation in
the transfer process can lead to reduced differential cross sections at higher
beam energies. This reduction would lead to the extraction of decreasing values
of S with increasing beam energy. A 10Be(d,p) measurement at Ed greater than 25
MeV is necessary to investigate the effects of core excitation in the reaction.