title:
On Whitham's conjecture of a highest cusped wave for a nonlocal
  dispersive equation

abstract:
  We consider the Whitham equation $u_t + 2u u_x+Lu_x = 0$, where L is the
nonlocal Fourier multiplier operator given by the symbol $m(\xi) = \sqrt{\tanh
\xi /\xi}$. G. B. Whitham conjectured that for this equation there would be a
highest, cusped, travelling-wave solution. We find this wave as a limiting case
at the end of the main bifurcation curve of $P$-periodic solutions, and give
several qualitative properties of it, including its optimal
$C^{1/2}$-regularity. An essential part of the proof consists in an analysis of
the integral kernel corresponding to the symbol $m(\xi)$, and a following study
of the highest wave. In particular, we show that the integral kernel
corresponding to the symbol $m(\xi)$ is completely monotone, and provide an
explicit representation formula for it.


title: Power-law cross-correlations estimation under heavy tails

abstract:
  We examine the performance of six estimators of the power-law
cross-correlations -- the detrended cross-correlation analysis, the detrending
moving-average cross-correlation analysis, the height cross-correlation
analysis, the averaged periodogram estimator, the cross-periodogram estimator
and the local cross-Whittle estimator -- under heavy-tailed distributions. The
selection of estimators allows to separate these into the time and frequency
domain estimators. By varying the characteristic exponent of the
$\alpha$-stable distributions which controls the tails behavior, we report
several interesting findings. First, the frequency domain estimators are
practically unaffected by heavy tails bias-wise. Second, the time domain
estimators are upward biased for heavy tails but they have lower estimator
variance than the other group for short series. Third, specific estimators are
more appropriate depending on distributional properties and length of the
analyzed series. In addition, we provide a discussion of implications of these
results for empirical applications as well as theoretical explanations.


title: Ramsey numbers of uniform loose paths and cycles

abstract:
  Recently, determining the Ramsey numbers of loose paths and cycles in uniform
hypergraphs has received considerable attention. It has been shown that the
$2$-color Ramsey number of a $k$-uniform loose cycle $\mathcal{C}^k_n$,
$R(\mathcal{C}^k_n,\mathcal{C}^k_n)$, is asymptotically $\frac{1}{2}(2k-1)n$.
Here we conjecture that for any $n\geq m\geq 3$ and $k\geq 3,$
$$R(\mathcal{P}^k_n,\mathcal{P}^k_m)=R(\mathcal{P}^k_n,\mathcal{C}^k_m)=R(\mathcal{C}^k_n,\mathcal{C}^k_m)+1=(k-1)n+\lfloor\frac{m+1}{2}\rfloor.$$
Recently the case $k=3$ is proved by the authors. In this paper, first we show
that this conjecture is true for $k=3$ with a much shorter proof. Then, we show
that for fixed $m\geq 3$ and $k\geq 4$ the conjecture is equivalent to (only)
the last equality for any $2m\geq n\geq m\geq 3$. Consequently, the proof for
$m=3$ follows.


title:
Limitations of generalised grey phonon models for quasiballistic thermal
  transport in time-periodic regimes

abstract:
  Suitably superimposed grey-medium solutions of the Boltzmann transport
equation (BTE) provide a simple yet accurate description of non-grey
quasiballistic heat conduction in transient thermal grating experiments. Recent
applications of similar strategies based on kinetic and
McKelvey-Schockley-Landauer theory to time-periodic transport predicted notable
conductivity suppression only at heating frequencies comparable to phonon
scattering rates, in contrast to lengthscale criteria observed by several prior
studies. Here we show that the frequency-integrated grey-medium approximation
(FIGMA) is ill suited to tackle temporally periodic quasiballistic transport.
Starting from first-principles phonon dispersions and scattering rates, we
obtain semi-analytic 1D BTE solutions for semi-infinite structures subjected to
sinusoidal surface heating and compare these to the approximate model
counterparts. We find FIGMA-based approaches to overestimate the semiconductor
surface temperature by up to one and characteristic heating frequencies for
onset of quasiballistic effects by up to three orders of magnitude
respectively. Our study reasserts that experimentally observed
heating-frequency dependent apparent conductivities originate in the overlap of
the characteristic length scale of the thermal gradient with phonon mean free
paths.


title:
Cross-Language Domain Adaptation for Classifying Crisis-Related Short
  Messages

abstract:
  Rapid crisis response requires real-time analysis of messages. After a
disaster happens, volunteers attempt to classify tweets to determine needs,
e.g., supplies, infrastructure damage, etc. Given labeled data, supervised
machine learning can help classify these messages. Scarcity of labeled data
causes poor performance in machine training. Can we reuse old tweets to train
classifiers? How can we choose labeled tweets for training? Specifically, we
study the usefulness of labeled data of past events. Do labeled tweets in
different language help? We observe the performance of our classifiers trained
using different combinations of training sets obtained from past disasters. We
perform extensive experimentation on real crisis datasets and show that the
past labels are useful when both source and target events are of the same type
(e.g. both earthquakes). For similar languages (e.g., Italian and Spanish),
cross-language domain adaptation was useful, however, when for different
languages (e.g., Italian and English), the performance decreased.


title: Microscopic study of $^{40}$Ca+$^{58,64}$Ni fusion reactions

abstract:
  Background: Heavy-ion fusion reactions at energies near the Coulomb barrier
are influenced by couplings between the relative motion and nuclear intrinsic
degrees of freedom of the colliding nuclei. The time-dependent Hartree-Fock
(TDHF) theory, incorporating the couplings at the mean-field level, as well as
the coupled-channels (CC) method are standard approaches to describe low energy
nuclear reactions.
  Purpose: To investigate the effect of couplings to inelastic and transfer
channels on the fusion cross sections for the reactions $^{40}$Ca+$^{58}$Ni and
$^{40}$Ca+$^{64}$Ni.
  Methods: Fusion cross sections around and below the Coulomb barrier have been
obtained from coupled-channels (CC) calculations, using the bare
nucleus-nucleus potential calculated with the frozen Hartree-Fock method and
coupling parameters taken from known nuclear structure data. The fusion
thresholds and neutron transfer probabilities have been calculated with the
TDHF method.
  Results: For $^{40}$Ca+$^{58}$Ni, the TDHF fusion threshold is in agreement
with the most probable barrier obtained in the CC calculations including the
couplings to the low-lying octupole $3_1^{-}$ state for $^{40}$Ca and to the
low-lying quadrupole $2_1^{+}$ state for $^{58}$Ni. This indicates that the
octupole and quadrupole states are the dominant excitations while neutron
transfer is shown to be weak. For $^{40}$Ca+$^{64}$Ni, the TDHF barrier is
lower than predicted by the CC calculations including the same inelastic
couplings as those for $^{40}$Ca+$^{58}$Ni. TDHF calculations show large
neutron transfer probabilities in $^{40}$Ca+$^{64}$Ni which could result in a
lowering of the fusion threshold.
  Conclusions: Inelastic channels play an important role in $^{40}$Ca+$^{58}$Ni
and $^{40}$Ca+$^{64}$Ni reactions. The role of neutron transfer channels has
been highlighted in $^{40}$Ca+$^{64}$Ni.


title:
Features of Low Temperature Tunnel Magnetoresistance in Pressed Powder
  of Chromium Dioxide

abstract:
  Resistive and magnetoresistive properties of two samples of compacted powders
of ferromagnetic half-metal CrO_{2} with shape anisotropy of nanoparticles were
studied. The powders were prepared by the method of hydrothermal synthesis and
consisted of needle-like particles with average diameters 24-34 nm and mean
length of 300 nm. One of the samples has been made of compacted powder of pure
CrO_{2}, while another sample has been prepared from a substitution solid
solution Cr_{1-x}Fe_{x}O_{2}. The aim of this work was to study the effect of
Fe impurity on the value of tunnel resistance and tunnel magnetoresistance for
compacted CrO_{2} powders. It was found that the addition of Fe impurity leads
to an increase in the coercive force of the powder and reduce the tunnel
magnetoresistance. We assume resonant tunneling mechanism on the Fe impurities.
We found a strong dependence of the magnetoresistance on the spin relaxation
rate in the process of magnetization reversal. The possible reasons for such
dependence are discussed.


title:
Simple average-case lower bounds for approximate near-neighbor from
  isoperimetric inequalities

abstract:
  We prove an $\Omega(d/\log \frac{sw}{nd})$ lower bound for the average-case
cell-probe complexity of deterministic or Las Vegas randomized algorithms
solving approximate near-neighbor (ANN) problem in $d$-dimensional Hamming
space in the cell-probe model with $w$-bit cells, using a table of size $s$.
This lower bound matches the highest known worst-case cell-probe lower bounds
for any static data structure problems.
  This average-case cell-probe lower bound is proved in a general framework
which relates the cell-probe complexity of ANN to isoperimetric inequalities in
the underlying metric space. A tighter connection between ANN lower bounds and
isoperimetric inequalities is established by a stronger richness lemma proved
by cell-sampling techniques.


title:
New observables for multiple-parton interactions measurements using Z +
  jets process at the LHC

abstract:
  Multiple-parton interactions play a vital role in hadron-hadron collisions.
This paper presents a study of the multiple-parton interactions with simulated
Z + jets events in proton-proton collisions at a centre-of-mass energy of 13
TeV. The events are simulated with POWHEG followed by hadronization and
parton-showering using PYTHIA 8. The events with dimuon invariant mass in the
range of 60--120 GeV are selected for the analysis. The charged particle jets,
having minimum transverse momentum of 5 GeV and absolute pseudo-rapidity less
than 2, are used to construct the observables for measurements of the
multiple-parton interactions. The proposed observables and phase-space region
presented in this paper found to have enhanced sensitivity to multiple-parton
interactions. The increased sensitivity to MPI will be lead to precise
constraints on the parameters of the MPI models.


title: Definable topological dynamics

abstract:
  For a group $G$ definable in a first order structure $M$ we develop basic
topological dynamics in the category of definable $G$-flows. In particular, we
give a description of the universal definable $G$-ambit and of the semigroup
operation on it. We find a natural epimorphism from the Ellis group of this
flow to the definable Bohr compactification of $G$, that is to the quotient
$G^*/{G^*}^{00}_M$ (where $G^*$ is the interpretation of $G$ in a monster
model). More generally, we obtain these results locally, i.e. in the category
of $\Delta$-definable $G$-flows for any fixed set $\Delta$ of formulas of an
appropriate form. In particular, we define local connected components
${G^*}^{00}_{\Delta,M}$ and ${G^*}^{000}_{\Delta,M}$, and show that
$G^*/{G^*}^{00}_{\Delta,M}$ is the $\Delta$-definable Bohr compactification of
$G$. We also note that some deeper arguments from the topological dynamics in
the category of externally definable $G$-flows can be adapted to the definable
context, showing for example that our epimorphism from the Ellis group to the
$\Delta$-definable Bohr compactification factors naturally yielding a
continuous epimorphism from the $\Delta$-definable generalized Bohr
compactification to the $\Delta$-definable Bohr compactification of $G$.
Finally, we propose to view certain topological-dynamic and model-theoretic
invariants as Polish structures which leads to some observations and questions.


title:
Online optimization and regret guarantees for non-additive long-term
  constraints

abstract:
  We consider online optimization in the 1-lookahead setting, where the
objective does not decompose additively over the rounds of the online game. The
resulting formulation enables us to deal with non-stationary and/or long-term
constraints , which arise, for example, in online display advertising problems.
We propose an on-line primal-dual algorithm for which we obtain dynamic
cumulative regret guarantees. They depend on the convexity and the smoothness
of the non-additive penalty, as well as terms capturing the smoothness with
which the residuals of the non-stationary and long-term constraints vary over
the rounds. We conduct experiments on synthetic data to illustrate the benefits
of the non-additive penalty and show vanishing regret convergence on live
traffic data collected by a display advertising platform in production.


title: Unifying Requirements and Code: an Example

abstract:
  Requirements and code, in conventional software engineering wisdom, belong to
entirely different worlds. Is it possible to unify these two worlds? A unified
framework could help make software easier to change and reuse. To explore the
feasibility of such an approach, the case study reported here takes a classic
example from the requirements engineering literature and describes it using a
programming language framework to express both domain and machine properties.
The paper describes the solution, discusses its benefits and limitations, and
assesses its scalability.


title: The beginnings of the Soviet encyclopedia

abstract:
  In this paper we focus on the beginning of publication of the Large Soviet
Encyclopedia, launched in 1925. We present the context of this launching and
explain why it was tightly connected to the period of the New Economical
Policy. In a last section, we examine four articles included in the first
volumes of the encyclopedia and relative to randomness and probability, in
order to illustrate some debates of the scientific scene in USSR during the
1920s.


title:
Adapted numerical methods for the numerical solution of the Poisson
  equation with $L^2$ boundary data in non-convex domains

abstract:
  The very weak solution of the Poisson equation with $L^2$ boundary data is
defined by the method of transposition. The finite element solution with
regularized boundary data converges in the $L^2(\Omega)$-norm with order $1/2$
in convex domains but has a reduced convergence order in non-convex domains
although the solution remains to be contained in $H^{1/2}(\Omega)$. The reason
is a singularity in the dual problem. In this paper we propose and analyze, as
a remedy, both a standard finite element method with mesh grading and a dual
variant of the singular complement method. The error order 1/2 is retained in
both cases also with non-convex domains. Numerical experiments confirm the
theoretical results.


title: The reverse mathematics of the Tietze extension theorem

abstract:
  We prove that several versions of the Tietze extension theorem for functions
with moduli of uniform continuity are equivalent to WKL_0 over RCA_0. This
confirms a conjecture of Giusto and Simpson that was also phrased as a question
in Montalb\'an's "Open questions in reverse mathematics."


title:
Modeling CD4+ T cells dynamics in HIV-infected patients receiving
  repeated cycles of exogenous Interleukin 7

abstract:
  Combination Antiretroviral Therapy (cART) succeeds to control viral
replication in most HIV infected patients. This is normally followed by a
reconstitution of the CD4$^+$ T cells pool; however, this does not happen for a
substantial proportion of patients. For these patients, an immunotherapy based
on injections of Interleukin 7 (IL-7) has been recently proposed as a
co-adjutant treatment in the hope of obtaining long-term reconstitution of the
T cells pool. Several questions arise as to the long-term efficiency of this
treatment and the best protocol to apply.
  We develop a model based on a system of ordinary differential equations and a
statistical model of variability and measurement. We can estimate key
parameters of this model using the data from INSPIRE, INSPIRE 2 $\&$ INSPIRE 3
trials. In all three studies, cycles of three injections have been
administered; in the last two studies, for the first time, repeated cycles of
exogenous IL-7 have been administered. Our aim was to estimate the possible
different effects of successive injections in a cycle, to estimate the effect
of repeated cycles and to assess different protocols.
  The use of dynamical models together with our complex statistical approach
allow us to analyze major biological questions. We found a strong effect of
IL-7 injections on the proliferation rate; however, the effect of the third
injection of the cycle appears to be much weaker than the first ones. Also,
despite a slightly weaker effect of repeated cycles with respect to the initial
one, our simulations show the ability of this treatment of maintaining adequate
CD4$^+$ T cells count for years. We were also able to compare different
protocols, showing that cycles of two injections should be sufficient in most
cases. %Finally, we also explore the possibility of adaptive protocols.


title:
Category theoretic semantics for theorem proving in logic programming:
  embracing the laxness

abstract:
  A propositional logic program $P$ may be identified with a $P_fP_f$-coalgebra
on the set of atomic propositions in the program. The corresponding
$C(P_fP_f)$-coalgebra, where $C(P_fP_f)$ is the cofree comonad on $P_fP_f$,
describes derivations by resolution. Using lax semantics, that correspondence
may be extended to a class of first-order logic programs without existential
variables. The resulting extension captures the proofs by term-matching
resolution in logic programming. Refining the lax approach, we further extend
it to arbitrary logic programs. We also exhibit a refinement of Bonchi and
Zanasi's saturation semantics for logic programming that complements lax
semantics.


title: On the lengths of zigzags in thin complexes

abstract:
  We consider zigzags in thin complexes. The main result states that the sum of
the lengths of all zigzags in an $n$-complexe is equal to the sum of the
lengths of all zigzags in all $(n-1)$-faces of this complex, and this sum also
is the twice of the sum of the lengths of all zigzags in all $(n-2)$-faces. For
simplicial and cubical $n$-complexes, the sum depends on the rank $n$ and the
number of $(n-1)$-faces only. We also describe the sum of the lengths of all
generalized zigzags, it depends on the rank and the number of flags. As an
application, we find the number of zigzags in Coxeter complexes.


title: Scatter fraction of the J-PET tomography scanner

abstract:
  A novel Positron Emission Tomography system, based on plastic scintillators,
is being developed by the J-PET collaboration. In this article we present the
simulation results of the scatter fraction, representing one of the parameters
crucial for background studies defined in the NEMA-NU-2-2012 norm. We elaborate
an event selection methods allowing to suppress events in which gamma quanta
were scattered in the phantom or underwent the multiple scattering in the
detector. The estimated scatter fraction for the single-layer J-PET scanner
varies from 37% to 53% depending on the applied energy threshold.


title: Construction of Bound Entangled States Based on Permutation Operators

abstract:
  We present a construction of new bound entangled states from given bound
entangled states for arbitrary dimensional bipartite systems. One way to
construct bound entangled states is to show that these states are PPT (positive
partial transpose) and violate the range criterion at the same time. By
applying certain operators to given bound entangled states or to one of the
subsystems of the given bound entangled states, we obtain a set of new states
which are both PPT and violate the range criterion. We show that the derived
bound entangled states are not local unitary equivalent to the original bound
entangled states by detail examples.


title: 11 x 11 Domineering is Solved: The first player wins

abstract:
  We have developed a program called MUDoS (Maastricht University Domineering
Solver) that solves Domineering positions in a very efficient way. This enables
the solution of known positions so far (up to the 10 x 10 board) much quicker
(measured in number of investigated nodes).
  More importantly, it enables the solution of the 11 x 11 Domineering board, a
board up till now far out of reach of previous Domineering solvers. The
solution needed the investigation of 259,689,994,008 nodes, using almost half a
year of computation time on a single simple desktop computer. The results show
that under optimal play the first player wins the 11 x 11 Domineering game,
irrespective if Vertical or Horizontal starts the game.
  In addition, several other boards hitherto unsolved were solved. Using the
convention that Vertical starts, the 8 x 15, 11 x 9, 12 x 8, 12 x 15, 14 x 8,
and 17 x 6 boards are all won by Vertical, whereas the 6 x 17, 8 x 12, 9 x 11,
and 11 x 10 boards are all won by Horizontal.


title:
Representational Realism, Closed Theories and the Quantum to Classical
  Limit

abstract:
  In this paper we discuss the representational realist stance as a pluralist
ontic approach to inter-theoretic relationships. Our stance stresses the fact
that physical theories require the necessary consideration of a conceptual
level of discourse which determines and configures the specific field of
phenomena discussed by each particular theory. We will criticize the orthodox
line of research which has grounded the analysis about QM in two (Bohrian)
metaphysical presuppositions -accepted in the present as dogmas that all
interpretations must follow. We will also examine how the orthodox project of
"bridging the gap" between the quantum and the classical domains has
constrained the possibilities of research, producing only a limited set of
interpretational problems which only focus in the justification of "classical
reality" and exclude the possibility of analyzing the possibilities of
non-classical conceptual representations of QM. The representational realist
stance introduces two new problems, namely, the superposition problem and the
contextuality problem, which consider explicitly the conceptual representation
of orthodox QM beyond the mere reference to mathematical structures and
measurement outcomes. In the final part of the paper, we revisit, from a
representational realist perspective, the quantum to classical limit and the
orthodox claim that this inter-theoretic relation can be explained through the
principle of decoherence.


title:
The Betti numbers of real toric varieties associated to Weyl chambers of
  type $B$

abstract:
  We compute the (rational) Betti number of real toric varieties associated to
Weyl chambers of type $B$. Furthermore, we show that their integral cohomology
is $p$-torsion free for all odd primes $p$.


title: Random bosonic states for robust quantum metrology

abstract:
  We study how useful random states are for quantum metrology, i.e., surpass
the classical limits imposed on precision in the canonical phase estimation
scenario. First, we prove that random pure states drawn from the Hilbert space
of distinguishable particles typically do not lead to super-classical scaling
of precision even when allowing for local unitary optimization. Conversely, we
show that random states from the symmetric subspace typically achieve the
optimal Heisenberg scaling without the need for local unitary optimization.
Surprisingly, the Heisenberg scaling is observed for states of arbitrarily low
purity and preserved under finite particle losses. Moreover, we prove that for
such states a standard photon-counting interferometric measurement suffices to
typically achieve the Heisenberg scaling of precision for all possible values
of the phase at the same time. Finally, we demonstrate that metrologically
useful states can be prepared with short random optical circuits generated from
three types of beam-splitters and a non-linear (Kerr-like) transformation.


title: PhotoRaptor - Photometric Research Application To Redshifts

abstract:
  Due to the necessity to evaluate photo-z for a variety of huge sky survey
data sets, it seemed important to provide the astronomical community with an
instrument able to fill this gap. Besides the problem of moving massive data
sets over the network, another critical point is that a great part of
astronomical data is stored in private archives that are not fully accessible
on line. So, in order to evaluate photo-z it is needed a desktop application
that can be downloaded and used by everyone locally, i.e. on his own personal
computer or more in general within the local intranet hosted by a data center.
The name chosen for the application is PhotoRApToR, i.e. Photometric Research
Application To Redshift (Cavuoti et al. 2015, 2014; Brescia 2014b). It embeds a
machine learning algorithm and special tools dedicated to preand
post-processing data. The ML model is the MLPQNA (Multi Layer Perceptron
trained by the Quasi Newton Algorithm), which has been revealed particularly
powerful for the photo-z calculation on the base of a spectroscopic sample
(Cavuoti et al. 2012; Brescia et al. 2013, 2014a; Biviano et al. 2013).
  The PhotoRApToR program package is available, for different platforms, at the
official website (http://dame.dsf.unina.it/dame_photoz.html#photoraptor).


title: Lasserre Lower Bounds and Definability of Semidefinite Programming

abstract:
  For a large class of optimization problems, namely those that can be
expressed as finite-valued constraint satisfaction problems (VCSPs), we
establish a dichotomy on the number of levels of the Lasserre hierarchy of
semi-definite programs (SDPs) that are required to solve the problem exactly.
In particular, we show that if a finite-valued constraint problem is not solved
exactly by its basic linear programming relaxation, it is also not solved
exactly by any sub-linear number of levels of the Lasserre hierarchy. The lower
bounds are established through logical undefinability results. We show that the
linear programming relaxation of the problem, as well as the SDP corresponding
to any fixed level of the Lasserre hierarchy is interpretable in a VCSP
instance by means of formulas of fixed-point logic with counting. We also show
that the solution of an SDP can be expressed in this logic. Together, these
results give a way of translating lower bounds on the number of variables
required in counting logic to express a VCSP into lower bounds on the number of
levels required in the Lasserre hierarchy to eliminate the integrality gap. As
a special case, we obtain the same dichotomy for the class of MAXCSP problems,
generalizing some earlier Lasserre lower bound results of Schoenebeck.


title: The Lyapunov dimension and its estimation via the Leonov method

abstract:
  Along with widely used numerical methods for estimating and computing the
Lyapunov dimension there is an effective analytical approach, proposed by G.A.
Leonov in 1991. The Leonov method is based on the direct Lyapunov method with
special Lyapunov-like functions. The advantage of this method is that it allows
one to estimate the Lyapunov dimension of invariant set without local- ization
of the set in the phase space and in many cases get effectively exact Lyapunov
dimension formula. In this survey the invariance of Lyapunov dimension with
respect to diffeomorphisms and its connection with the Leonov method are
discussed. An analog of Leonov method for discrete time dynamical systems is
suggested. In a simple but rigorous way, here it is presented the connection
between the Leonov method and the key related works in the area: by Kaplan and
Yorke (the concept of Lyapunov dimension, 1979), Douady and Oesterle (upper
bounds of Hausdorff dimension via the Lyapunov dimension of maps, 1980),
Constantin, Eden, Foias, and Temam (upper bounds of Hausdorff dimension via the
Lyapunov exponents and dimension of dynamical systems, 1985-90), and the
numerical calculation of the Lyapunov exponents and dimension.


title:
High-energy Neutrino follow-up search of Gravitational Wave Event
  GW150914 with ANTARES and IceCube

abstract:
  We present the high-energy-neutrino follow-up observations of the first
gravitational wave transient GW150914 observed by the Advanced LIGO detectors
on Sept. 14th, 2015. We search for coincident neutrino candidates within the
data recorded by the IceCube and ANTARES neutrino detectors. A possible joint
detection could be used in targeted electromagnetic follow-up observations,
given the significantly better angular resolution of neutrino events compared
to gravitational waves. We find no neutrino candidates in both temporal and
spatial coincidence with the gravitational wave event. Within 500 s of the
gravitational wave event, the number of neutrino candidates detected by IceCube
and ANTARES were three and zero, respectively. This is consistent with the
expected atmospheric background, and none of the neutrino candidates were
directionally coincident with GW150914. We use this non-detection to constrain
neutrino emission from the gravitational-wave event.


title:
A unique model for the variety of multiple populations formation(s) in
  globular clusters: a temporal sequence

abstract:
  We explain the multiple populations recently found in the 'prototype'
Globular Cluster (GC) NGC 2808 in the framework of the asymptotic giant branch
(AGB) scenario. The chemistry of the five -or more- populations is
approximately consistent with a sequence of star formation events, starting
after the supernovae type II epoch, lasting approximately until the time when
the third dredge up affects the AGB evolution (age ~90-120Myr), and ending when
the type Ia supernovae begin exploding in the cluster, eventually clearing it
from the gas. The formation of the different populations requires episodes of
star formation in AGB gas diluted with different amounts of pristine gas. In
the nitrogen-rich, helium-normal population identified in NGC 2808 by the UV
Legacy Survey of GCs, the nitrogen increase is due to the third dredge up in
the smallest mass AGB ejecta involved in the star formation of this population.
The possibly-iron-rich small population in NGC 2808 may be a result of
contamination by a single type Ia supernova. The NGC 2808 case is used to build
a general framework to understand the variety of 'second generation' stars
observed in GCs. Cluster-to-cluster variations are ascribed to differences in
the effects of the many processes and gas sources which may be involved in the
formation of the second generation. We discuss an evolutionary scheme, based on
pollution by delayed type II supernovae, which accounts for the properties of
s-Fe-anomalous clusters.


title: Diffusion of innovation in large scale graphs

abstract:
  Will a new smartphone application diffuse deeply in the population or will it
sink into oblivion soon? To predict this, we argue that common models of spread
of innovations based on cascade dynamics or epidemics may not be fully
adequate. Therefore we propose a novel stochastic network dynamics modeling the
spread of a new technological asset, whose adoption is based on the
word-of-mouth and the persuasion strength increases the more the product is
diffused. In this paper we carry on an analysis on large scale graphs to show
off how the parameters of the model, the topology of the graph and, possibly,
the initial diffusion of the asset, determine whether the spread of the asset
is successful or not. In particular, by means of stochastic dominations and
deterministic approximations, we provide some general results for a large class
of expansive graphs. Finally we present numerical simulations trying to expand
the analytical results we proved to even more general topologies.


title: Ricci curvature bounds for weakly interacting Markov chains

abstract:
  We establish a general perturbative method to prove entropic Ricci curvature
bounds for interacting stochastic particle systems. We apply this method to
obtain curvature bounds in several examples, namely: Glauber dynamics for a
class of spin systems including the Ising and Curie--Weiss models, a class of
hard-core models and random walks on groups induced by a conjugacy invariant
set of generators.


title: On flux vacua, SU(n)-structures and generalised complex geometry

abstract:
  Understanding supersymmetric flux vacua is essential in order to connect
string theory to observable physics. In this thesis, flux vacua are studied by
making use of two mathematical frameworks: SU(n)-structures and generalised
complex geometry. Manifolds with SU(n)-structure are generalisations of
Calabi-Yau manifolds. Generalised complex geometry is a geometrical framework
that simultaneously generalises complex and symplectic geometry. Classes of
flux vacua of type II supergravity and M-theory are given on manifolds with
SU(4)-structure. The N= (1,1) type IIA vacua uplift to N=1 M-theory vacua, with
four-flux that need not be (2,2) and primitive. Explicit vacua are given on
Stenzel space, a non-compact Calabi-Yau. These are then generalised by
constructing families of non-CY SU(4)-structures to find vacua on
non-symplectic SU(4)-deformed Stenzel spaces. It is shown that the
supersymmetry conditions for N = (2,0) type IIB can be rephrased in the
language of generalised complex geometry, partially in terms of integrability
conditions of generalised almost complex structures. This rephrasing for d=2
goes beyond the calibration equations, in contrast to d=4,6 where the
calibration equations are equivalent to supersymmetry. Finally, Euclidean type
II theory is examined on SU(5)-structure manifolds, where generalised equations
are found which are necessary but not sufficient to satisfy the supersymmetry
equations. Explicit classes of solutions are provided here as well. Contact
with Lorentzian physics can be made by uplifting such solutions to d=1, N=1
M-theory.


title: Cluster-based control of nonlinear dynamics

abstract:
  The ability to manipulate and control fluid flows is of great importance in
many scientific and engineering applications. Here, a cluster-based control
framework is proposed to determine optimal control laws with respect to a cost
function for unsteady flows. The proposed methodology frames high-dimensional,
nonlinear dynamics into low-dimensional, probabilistic, linear dynamics which
considerably simplifies the optimal control problem while preserving nonlinear
actuation mechanisms. The data-driven approach builds upon a state space
discretization using a clustering algorithm which groups kinematically similar
flow states into a low number of clusters. The temporal evolution of the
probability distribution on this set of clusters is then described by a Markov
model. The Markov model can be used as predictor for the ergodic probability
distribution for a particular control law. This probability distribution
approximates the long-term behavior of the original system on which basis the
optimal control law is determined. The approach is applied to a separating flow
dominated by the Kelvin-Helmholtz shedding.


title: Telegraph equations for the case of a waveguide with moving boundary

abstract:
  Telegraph equation describing the compression of electromagnetic waves in a
waveguide (resonator) with moving boundary are derived. It is shown that the
character of oscillations of the compressed electromagnetic field depends on
the parameters of the resonator, and under certain conditions, the oscillations
of voltage (current) yield the exponential growth, leading to a noticeable
change in the radiation losses.


title:
Local negativity of surfaces with non-negative Koidara dimension and
  transversal configurations of curves

abstract:
  We give a bound on the H-constants of configurations of smooth curves having
transversal intersection points only on an algebraic surface of non-negative
Kodaira dimension. We also study in detail configurations of lines on smooth
complete intersections $X \subset \mathbb{P}^{n+2}_{\mathbb{C}}$ of
multi-degree $d=(d_1, \dots, d_n)$, and we provide a sharp and uniform bound on
their H-constants, which only depends on $d$.


title:
Harder, Better, Faster, Stronger Convergence Rates for Least-Squares
  Regression

abstract:
  We consider the optimization of a quadratic objective function whose
gradients are only accessible through a stochastic oracle that returns the
gradient at any given point plus a zero-mean finite variance random error. We
present the first algorithm that achieves jointly the optimal prediction error
rates for least-squares regression, both in terms of forgetting of initial
conditions in O(1/n 2), and in terms of dependence on the noise and dimension d
of the problem, as O(d/n). Our new algorithm is based on averaged accelerated
regularized gradient descent, and may also be analyzed through finer
assumptions on initial conditions and the Hessian matrix, leading to
dimension-free quantities that may still be small while the " optimal " terms
above are large. In order to characterize the tightness of these new bounds, we
consider an application to non-parametric regression and use the known lower
bounds on the statistical performance (without computational limits), which
happen to match our bounds obtained from a single pass on the data and thus
show optimality of our algorithm in a wide variety of particular trade-offs
between bias and variance.


title: Coming to see fractions on the numberline

abstract:
  The aim of this paper is to present a didactical sequence that fosters the
development of meanings related to fractions, conceived as numbers that can be
placed on the number line. The sequence was carried out in various elementary
school classes, containing students certified to have mathematical learning
disabilities (MLD). Thus, our didactical aim is to make accessible meaning
related to fractions to all students of the class, including MLD students, by
means of a common didactical sequence, that is, a sequence proposed to the
entire class. Our research is based on a range of different perspectives, from
mathematics education to neuroscience and cognitive psychology. We discuss how
such perspectives can be combined and provide the theoretical bases to design
an outline of the didactical sequence, which allows us to implement and
strengthen inclusive education.


title: $\mu$MECH Micromechanics Library

abstract:
  The paper presents the project of an open source C/C++ library of analytical
solutions to micromechanical fields within media with ellipsoidal
heterogeneities. The solutions are based on Eshelby's stress-free, in general
polynomial, eigenstrains and equivalent inclusion method. To some extent, the
interactions among inclusions in a non-dilute medium are taken into account by
means of the self-compatibility algorithm. Moreover, the library is furnished
with a powerful I/O interface and conventional homogenization tools. Advantages
and limitations of the implemented strategies are addressed through comparisons
with reference solutions by means of the Finite Element Method.


title: The Kuratowski convergence of medial axes and conflict sets

abstract:
  This paper consists of two parts. In the first one we study the behaviour of
medial axes (skeletons) of closed, definable (in some o-minimal structure) sets
in ${\Rz}^n$ under deformations. The second one is devoted to a similar study
of conflict sets in definable families. We apply a new approach to the
deformation process. Instead of seeing it as a `jump' from the initial to the
final state, we perceive it as a continuous process, expressed using the
Kuratowski convergence of sets (hence, unlike other authors, we do not require
any regularity of the deformation). Our main `medial axis inner
semi-continuity' result has already proved useful, as it was used to compute
the tangent cone of the medial axis with application in singularity theory.


title: Tau-structure for the Double Ramification Hierarchies

abstract:
  In this paper we continue the study of the double ramification hierarchy of
[Bur15]. After showing that the DR hierarchy satisfies tau-symmetry we define
its partition function as the (logarithm of the) tau-function of the string
solution and show that it satisfies various properties (string, dilaton and
divisor equations plus some important degree constraints). We then formulate a
stronger version of the conjecture from [Bur15]: for any semisimple
cohomological field theory, the Dubrovin-Zhang and double ramification
hierarchies are related by a normal (i.e. preserving the tau-structure
[DLYZ14]) Miura transformation which we completely identify in terms of the
partition function of the CohFT. In fact, using only the partition functions,
the conjecture can be formulated even in the non-semisimple case (where the
Dubrovin-Zhang hierarchy is not defined). We then prove this conjecture for
various CohFTs (trivial CohFT, Hodge class, Gromov-Witten theory of
$\mathbb{CP}^1$, $3$-, $4$- and $5$-spin classes) and in genus $1$ for any
semisimple CohFT. Finally we prove that the higher genus part of the DR
hierarchy is basically trivial for the Gromov-Witten theory of smooth varieties
with non-positive first Chern class and their analogue in
Fan-Jarvis-Ruan-Witten quantum singularity theory [FJRW].


title:
Weak and strong coupling limits of the Boltzmann equation in the
  relaxation-time approximation

abstract:
  We consider a momentum dependent relaxation time for the Boltzmann equation
in the relaxation time approximation. We employ a power law parametrization for
the momentum dependence of the relaxation time, and calculate the shear and
bulk viscosity, as well as, the charge and heat conductivity. We show, that for
the two popular parametrizations, referred to as the linear and quadratic
ansatz, one can obtain transport coefficients which corresponds to the weak and
strong coupling regimes, respectively. We also show that, for a system of
massless particles with vanishing chemical potential, the off-equilibrium
corrections to the phase-space distribution function calculated with the
quadratic ansatz are identical with those of the Grad's 14-moment method.


title:
Study of adiabatic connection in density functional theory with an
  accurate wavefunction for 2-electron atoms

abstract:
  Using an accurate semi-analytic wavefunction for two electron atoms, we
construct the external potential for varying strength of electron-electron
(e-e) interaction. Using this potential we explicitly calculate the energy of
their positive ion and show that the ionization-potential of these systems
remains unchanged with respect to the strength parameter for e-e interaction.
Furthermore, using total energies of these systems as a function of strength
parameter, we provide a new perspective into a variety of hybrid functionals.


title: On Quantum Theory

abstract:
  A discussion of fundamental aspects of quantum theory is presented, stressing
the essential role of "events". (Abstract by Erhard Seiler -- see afterword)


title: Composite Accidental Axions

abstract:
  We present several models where the QCD axion arises accidentally. Confining
gauge theories can generate axion candidates whose properties are uniquely
determined by the quantum numbers of the new fermions under the Standard Model.
The Peccei-Quinn symmetry can emerge accidentally if the gauge theory is
chiral. We generalise previous constructions in a unified framework. In some
cases these models can be understood as the deconstruction of 5-dimensional
gauge theories where the Peccei-Quinn symmetry is protected by locality but
more general constructions are possible.


title:
Using pivot signs to reach an inclusive definition of squares and
  rectangles

abstract:
  We present some fragments of a teaching experiment realized in a first grade
classroom, to sow the seeds for a mathematical definition of rectangles that
includes squares. Within the paradigm of semiotic mediation, we studied the
emergence of pivot signs, which were exploited by the teacher to pave the way
towards an inclusive definition of rectangles and squares. This was done to
favor overcoming children's spontaneous distinction of these figures into
distinct categories, reinforced by everyday language. The experiment is an
example of an approach towards the theoretical dimension of mathematics in
early childhood.


title: Invariants for links from classical and affine Yokonuma--Hecke algebras

abstract:
  We present a construction of invariants for links using an isomorphism
theorem for affine Yokonuma--Hecke algebras. The isomorphism relates affine
Yokonuma--Hecke algebras with usual affine Hecke algebras. We use it to
construct a large class of Markov traces on affine Yokonuma--Hecke algebras,
and in turn, to produce invariants for links in the solid torus. By
restriction, this construction contains the construction of invariants for
classical links from classical Yokonuma--Hecke algebras. In general, the
obtained invariants form an infinite family of 3-variables polynomials. As a
consequence of the construction via the isomorphism, we reduce the number of
invariants to study, given the number of connected components of a link. In
particular, if the link is a classical link with N components, we show that N
invariants generate the whole family.


title: Rovibrationally-Resolved Photodissociaton of SH$^+$

abstract:
  Photodissociation cross sections for the SH$^+$ radical are computed from all
rovibrational (RV) levels of the ground electronic state X$~^3\Sigma^-$ for
wavelengths from threshold to 500~\AA. The five electronic transitions, $2~
^3\Sigma^- \leftarrow$ X$~^3\Sigma^-$, $3~ ^3\Sigma^- \leftarrow$
X$~^3\Sigma^-$, $A~ ^3\Pi \leftarrow$ X$~^3\Sigma^-$, $2~ ^3\Pi \leftarrow$
X$~^3\Sigma^-$, and $3~ ^3\Pi \leftarrow$ X$~^3\Sigma^-$, are treated with a
fully quantum-mechanical two-state model, {i.e. no non-adiabatic coupling
between excited states was included in our work.}. The photodissociation
calculations incorporate adiabatic potentials and transition dipole moment
functions computed in the multireference configuration interaction approach
along with the Davidson correction (MRCI+Q), but adjusted to match available
experimental molecular data and asymptotic atomic limits. Local thermodynamic
equilibrium (LTE) photodissociation cross sections were computed which assume a
Boltzmann distribution of RV levels in the X$~^3\Sigma^-$ molecular state of
the SH$^+$ cation. The LTE cross sections are presented for temperatures in the
range 1000-10,000~K. Applications of the current photodissociation cross
sections to interstellar gas, photon-dominated regions, and stellar atmospheres
are briefly discussed.


title: Propagating speed of primordial gravitational waves and inflation

abstract:
  We show that if the propagating speed of gravitational waves (GWs) gradually
diminishes during inflation, the power spectrum of primordial GWs will be
strongly blue, while that of the primordial scalar perturbation may be
unaffected. We also illustrate that such a scenario is actually a disformal
dual to the superinflation, but it does not have the ghost instability. The
blue tilt obtained is $0<n_T\lesssim 1$, which may significantly boost the
stochastic GWs background at the frequency band of Advanced LIGO/Virgo, as well
as the space-based detectors.


title: Language recognition power and succintness of affine automata

abstract:
  In this work we study a non-linear generalization based on affine
transformations of probabilistic and quantum automata proposed recently by
D\'iaz-Caro and Yakary{\i}lmaz \cite{DCY16A} referred as affine automata.
First, we present efficient simulations of probabilistic and quantum automata
by means of affine automata which allows us to characterize the class of
exclusive stochastic languages. Then, we initiate a study on the succintness of
affine automata. In particular, we show that an infinite family of unary
regular languages can be recognized by 2-state affine automata but the state
numbers of quantum and probabilistic automata cannot be bounded. Finally, we
present the characterization of all (regular) unary languages recognized by
two-state affine automata.


title:
Modeling of screening currents in coated conductor magnets containing up
  to 40000 turns

abstract:
  Screening currents caused by varying magnetic fields degrade the homogeneity
and stability of the magnetic fields created by $RE$BCO coated conductor coils.
They are responsible for the AC loss, which is also important for other power
applications containing windings. Since real magnets contain coils exceeding
10000 turns, accurate modeling tools for this number of turns are necessary for
magnet design. This article presents a fast numerical method to model coils
with no loss of accuracy. We model a 10400-turn coil for its real geometry and
coils of up to 40000 turns with the continuous approximation, which we checked
that introduces negligible errors. The screening currents, the Screening
Current Induced Field (SCIF) and the AC loss is analyzed in detail. The SCIF is
maximum at the remnant state with a considerably large value and decreases
substantially after one day of relaxation. The instantaneous AC loss for an
anisotropic magnetic-field dependent $J_c$ is qualitatively different than for
a constant $J_c$, although the loss per cycle is similar. Saturation of the
magnetization currents at the end pancakes causes that the maximum AC loss at
the first ramp increases with $J_c$. The presented modeling tool can accurately
calculate the SCIF and AC loss in practical computing times for coils with any
number of turns used in real windings, enabling parameter optimization.


title:
Exchange-correlation functionals via local interpolation along the
  adiabatic connection

abstract:
  The construction of density-functional approximations is explored by modeling
the adiabatic connection em locally, using energy densities defined in terms of
the electrostatic potential of the exchange-correlation hole. These local
models are more amenable to the construction of size-consistent approximations
than their global counterparts. In this work we use accurate input local
ingredients to assess the accuracy of range of local interpolation models
against accurate exchange-correlation energy densities. The importance of the
strictly-correlated electrons (SCE) functional describing the strong coupling
limit is emphasized, enabling the corresponding interpolated functionals to
treat strong correlation effects. In addition to exploring the performance of
such models numerically for the helium and beryllium isoelectronic series and
the dissociation of the hydrogen molecule, an approximate analytic model is
presented for the initial slope of the local adiabatic connection. Comparisons
are made with approaches based on global models and prospects for future
approximations based on the local adiabatic connection are discussed.


title:
Ultrafast x-ray diffraction of a ferroelectric soft mode driven by
  broadband terahertz pulses

abstract:
  Intense, few-cycle pulses in the terahertz frequency range have strong
potential for schemes of control over vibrational modes in solid-state
materials in the electronic ground-state. Here we report an experiment using
single cycle terahertz pulses to directly excite lattice vibrations in the
ferroelectric material $\mathrm{Sn_2P_2S_6}$ and ultrafast x-ray diffraction to
quantify the resulting structural dynamics. A model of a damped harmonic
oscillator driven by the transient electric field of the terahertz pulses
describes well the movement of the Sn$^{2+}$ ion along the ferroelectric soft
mode. Finally, we describe an anharmonic extension of this model which predicts
coherent switching of domains at peak THz-frequency fields of 790 kV/cm.


title:
Low-Rank Factorization of Determinantal Point Processes for
  Recommendation

abstract:
  Determinantal point processes (DPPs) have garnered attention as an elegant
probabilistic model of set diversity. They are useful for a number of subset
selection tasks, including product recommendation. DPPs are parametrized by a
positive semi-definite kernel matrix. In this work we present a new method for
learning the DPP kernel from observed data using a low-rank factorization of
this kernel. We show that this low-rank factorization enables a learning
algorithm that is nearly an order of magnitude faster than previous approaches,
while also providing for a method for computing product recommendation
predictions that is far faster (up to 20x faster or more for large item
catalogs) than previous techniques that involve a full-rank DPP kernel.
Furthermore, we show that our method provides equivalent or sometimes better
predictive performance than prior full-rank DPP approaches, and better
performance than several other competing recommendation methods in many cases.
We conduct an extensive experimental evaluation using several real-world
datasets in the domain of product recommendation to demonstrate the utility of
our method, along with its limitations.


title: Distributed Strong Diameter Network Decomposition

abstract:
  For a pair of positive parameters $D,\chi$, a partition ${\cal P}$ of the
vertex set $V$ of an $n$-vertex graph $G = (V,E)$ into disjoint clusters of
diameter at most $D$ each is called a $(D,\chi)$ network decomposition, if the
supergraph ${\cal G}({\cal P})$, obtained by contracting each of the clusters
of ${\cal P}$, can be properly $\chi$-colored. The decomposition ${\cal P}$ is
said to be strong (resp., weak) if each of the clusters has strong (resp.,
weak) diameter at most $D$, i.e., if for every cluster $C \in {\cal P}$ and
every two vertices $u,v \in C$, the distance between them in the induced graph
$G(C)$ of $C$ (resp., in $G$) is at most $D$.
  Network decomposition is a powerful construct, very useful in distributed
computing and beyond. It was shown by Awerbuch \etal \cite{AGLP89} and
Panconesi and Srinivasan \cite{PS92}, that strong $(2^{O(\sqrt{\log
n})},2^{O(\sqrt{\log n})})$ network decompositions can be computed in
$2^{O(\sqrt{\log n})}$ distributed time. Linial and Saks \cite{LS93} devised an
ingenious randomized algorithm that constructs {\em weak} $(O(\log n),O(\log
n))$ network decompositions in $O(\log^2 n)$ time. It was however open till now
if {\em strong} network decompositions with both parameters $2^{o(\sqrt{\log
n})}$ can be constructed in distributed $2^{o(\sqrt{\log n})}$ time.
  In this paper we answer this long-standing open question in the affirmative,
and show that strong $(O(\log n),O(\log n))$ network decompositions can be
computed in $O(\log^2 n)$ time. We also present a tradeoff between parameters
of our network decomposition. Our work is inspired by and relies on the
"shifted shortest path approach", due to Blelloch \etal \cite{BGKMPT11}, and
Miller \etal \cite{MPX13}. These authors developed this approach for PRAM
algorithms for padded partitions. We adapt their approach to network
decompositions in the distributed model of computation.


title:
Drell-Yan production of multi Z'-bosons at the LHC within Non-Universal
  ED and 4D Composite Higgs Models

abstract:
  The Drell-Yan di-lepton production at hadron colliders is by far the
preferred channel to search for new heavy spin-1 particles. Traditionally, such
searches have exploited the Narrow Width Approximation (NWA) for the signal,
thereby neglecting the effect of the interference between the additional
Z'-bosons and the Standard Model Z and {\gamma}. Recently, it has been
established that both finite width and interference effects can be dealt with
in experimental searches while still retaining the model independent approach
ensured by the NWA. This assessment has been made for the case of popular
single Z'-boson models currently probed at the CERN Large Hadron Collider
(LHC). In this paper, we test the scope of the CERN machine in relation to the
above issues for some benchmark multi Z'-boson models. In particular, we
consider Non-Universal Extra Dimensional (NUED) scenarios and the 4-Dimensional
Composite Higgs Model (4DCHM), both predicting a multi-Z' peaking structure. We
conclude that in a variety of cases, specifically those in which the leptonic
decays modes of one or more of the heavy neutral gauge bosons are suppressed
and/or significant interference effects exist between these or with the
background, especially present when their decay widths are significant,
traditional search approaches based on the assumption of rather narrow and
isolated objects might require suitable modifications to extract the underlying
dynamics.


title: Cell segmentation with random ferns and graph-cuts

abstract:
  The progress in imaging techniques have allowed the study of various aspect
of cellular mechanisms. To isolate individual cells in live imaging data, we
introduce an elegant image segmentation framework that effectively extracts
cell boundaries, even in the presence of poor edge details. Our approach works
in two stages. First, we estimate pixel interior/border/exterior class
probabilities using random ferns. Then, we use an energy minimization framework
to compute boundaries whose localization is compliant with the pixel class
probabilities. We validate our approach on a manually annotated dataset.


title:
Surveying students' understanding of quantum mechanics in one spatial
  dimension

abstract:
  We explore the difficulties that advanced undergraduate and graduate students
have with non-relativistic quantum mechanics of a single particle in one
spatial dimension. To investigate these difficulties we developed a conceptual
survey and administered it to more than 200 students at 10 institutions. The
issues targeted in the survey include the set of possible wavefunctions, bound
and scattering states, quantum measurement, expectation values, the role of the
Hamiltonian, and the time-dependence of the wavefunction and expectation
values. We find that undergraduate and graduate students have many common
difficulties with these concepts and that research-based tutorials and
peer-instruction tools can significantly reduce these difficulties. The
findings also suggest that graduate quantum mechanics courses may not be
effective at helping students to develop a better conceptual understanding of
these topics, partly because such courses mainly focus on quantitative
assessments.


title: Monoidal Categories, 2-Traces, and Cyclic Cohomology

abstract:
  In this paper we show that to a unital associative algebra object (resp.
co-unital co-associative co-algebra object) of any abelian monoidal category
$\mathcal{C}$ endowed with a symmetric $2$-trace, one can attach a cyclic
(resp. cocyclic) module, and therefore speak of the cyclic (co)homology of the
(co)algebra "with coefficients in $F$". We observe that if $\mathcal{M}$ is a
$\mathcal{C}$-bimodule category equipped with a stable central pair then
$\mathcal{C}$ acquires a symmetric 2-trace. The dual notions of symmetric
$2$-contratraces and stable central contrapairs are derived as well. As an
application we can recover all Hopf cyclic type (co)homology theories, obtain a
conceptual understanding of anti-Yetter-Drinfeld modules, and give a
formula-free definition of cyclic cohomology. The machinery can also be applied
in settings more general than Hopf algebra modules and comodules.


title:
The effect of roll number on the statistics of turbulent Taylor-Couette
  flow

abstract:
  A series of direct numerical simulations in large computational domains has
been performed in order to probe the spatial feature robustness of the Taylor
rolls in turbulent Taylor-Couette (TC) flow. The latter is the flow between two
coaxial independently rotating cylinders of radius $r_i$ and $r_o$,
respectively. Large axial aspect ratios $\Gamma = 7$-$8$ (with $\Gamma =
L/(r_o-r_i)$, and $L$ the axial length of the domain) and a simulation with
$\Gamma=14$ were used in order to allow the system to select the most unstable
wavenumber and to possibly develop multiple states. The radius ratio was taken
as $\eta=r_i/r_o=0.909$, the inner cylinder Reynolds number was fixed to
$Re_i=3.4\cdot10^4$, and the outer cylinder was kept stationary, resulting in a
frictional Reynolds number of $Re_\tau\approx500$, except for the $\Gamma=14$
simulation where $Re_i=1.5\cdot10^4$ and $Re_\tau\approx240$. The large-scale
rolls were found to remain axially pinned for all simulations. Depending on the
initial conditions, stable solutions with different number of rolls $n_r$ and
roll wavelength $\lambda_z$ were found for $\Gamma=7$. The effect of
$\lambda_z$ and $n_r$ on the statistics was quantified. The torque and mean
flow statistics were found to be independent of both $\lambda_z$ and $n_r$,
while the velocity fluctuations and energy spectra showed some box-size
dependence. Finally, the axial velocity spectra was found to have a very sharp
drop off for wavelengths larger than $\lambda_z$, while for the small
wavelengths they collapse.


title:
Signature of Wave Chaos in Spectral Characteristics of Microcavity
  Lasers

abstract:
  We report the spectral characteristics of fully chaotic and non-chaotic
microcavity lasers under continuous-wave operating conditions. It is found that
fully chaotic microcavity lasers operate in single mode, whereas non-chaotic
microcavity lasers operate in multimode. The suppression of multimode lasing
for fully chaotic microcavity lasers is explained by large spatial overlaps of
the resonance wave functions that spread throughout the two-dimensional cavity
due to the ergodicity of chaotic ray orbits.


title: A sparse Fast Fourier Algorithm for Real Nonnegative Vectors

abstract:
  In this paper we propose a new fast Fourier transform to recover a real
nonnegative signal ${\bf x}$ from its discrete Fourier transform. If the signal
${\mathbf x}$ appears to have a short support, i.e., vanishes outside a support
interval of length $m < N$, then the algorithm has an arithmetical complexity
of only ${\cal O}(m \log m \log (N/m)) $ and requires ${\cal O}(m \log (N/m))$
Fourier samples for this computation. In contrast to other approaches there is
no a priori knowledge needed about sparsity or support bounds for the vector
${\bf x}$. The algorithm automatically recognizes and exploits a possible short
support of the vector and falls back to a usual radix-2 FFT algorithm if ${\bf
x}$ has (almost) full support. The numerical stability of the proposed
algorithm ist shown by numerical examples.


title:
Performance Analysis of Project-and-Forward Relaying in Mixed
  MIMO-Pinhole and Rayleigh Dual-Hop Channel

abstract:
  In this letter, we present an end-to-end performance analysis of dual-hop
project-and-forward relaying in a realistic scenario, where the source-relay
and the relay-destination links are experiencing MIMO-pinhole and Rayleigh
channel conditions, respectively. We derive the probability density function of
both the relay post-processing and the end-to-end signal-to-noise ratios, and
the obtained expressions are used to derive the outage probability of the
analyzed system as well as its end-to-end ergodic capacity in terms of
generalized functions. Applying then the residue theory to Mellin-Barnes
integrals, we infer the system asymptotic behavior for different channel
parameters. As the bivariate Meijer-G function is involved in the analysis, we
propose a new and fast MATLAB implementation enabling an automated definition
of the complex integration contour. Extensive Monte-Carlo simulations are
invoked to corroborate the analytical results.


title:
Classification of quasi-symmetric 2-(64,24,46) designs of
  Blokhuis-Haemers type

abstract:
  This paper completes the classification of quasi-symmetric 2-$(64,24,46)$
designs of Blokhuis-Haemers type supported by the dual code $C^{\perp}$ of the
binary linear code $C$ spanned by the lines of $AG(3,2^2)$ initiated in
\cite{bgr-vdt}. It is shown that $C^{\perp}$ contains exactly 30,264
nonisomorphic quasi-symmetric 2-$(64,24,46)$ designs obtainable from maximal
arcs in $AG(2,2^2)$ via the Blokhuis-Haemers construction. The related strongly
regular graphs are also discussed.


title:
Continuity equation for probability as a requirement of inference over
  paths

abstract:
  In this work we present the fundamental ideas of inference over paths, and
show how this formalism implies the continuity equation, which is central for
the derivation of the main partial differential equations that constitute
non-equilibrium statistical mechanics. Equations such as the Liouville
equation, Fokker-Planck equation, among others can be recovered as particular
cases of the continuity equation, under different probability fluxes. We derive
the continuity equation in its most general form through what we call the \bf
time-slicing equation, which lays down the procedure to go from the
representation in terms of a path probability functional $\rho[X()]$ to a
time-dependent probability density $\rho(x; t)$. The original probability
functional $\rho[X()]$ can in principle be constructed from different methods
of inference; in this work we sketch an application using the maximum path
entropy or maximum caliber principle.


title: Optimal measurements for nonlocal correlations

abstract:
  A problem in quantum information theory is to find the experimental setup
that maximizes the nonlocality of correlations with respect to some suitable
measure such as the violation of Bell inequalities. The latter has however some
drawbacks. First and foremost it is unfeasible to determine the whole set of
Bell inequalities already for a few measurements and thus unfeasible to find
the experimental setup maximizing their violation. Second, the Bell violation
suffers from an ambiguity stemming from the choice of the normalization of the
Bell coefficients. An alternative measure of nonlocality with a direct
information-theoretic interpretation is the minimal amount of classical
communication required for simulating nonlocal correlations. In the case of
many instances simulated in parallel, the minimal communication cost per
instance is called nonlocal capacity, and its computation can be reduced to a
convex-optimization problem. This quantity can be computed for a higher number
of measurements and turns out to be useful for finding the optimal experimental
setup. Focusing on the bipartite case, in this paper, we present a simple
method for maximizing the nonlocal capacity over a given configuration space
and, in particular, over a set of possible measurements, yielding the
corresponding optimal setup. Furthermore, we show that there is a functional
relationship between Bell violation and nonlocal capacity. The method is
illustrated with numerical tests and compared with the maximization of the
violation of CGLMP-type Bell inequalities on the basis of entangled two-qubit
as well as two-qutrit states. Remarkably, the anomaly of nonlocality displayed
by qutrits turns out to be even stronger if the nonlocal capacity is employed
as a measure of nonlocality.


title:
On the analysis of stage I in the resistivity recovery of electron
  irradiated iron

abstract:
  The experimental results of Takaki et al. [1] on the stage I resistivity
recovery of electron irradiated iron are analyzed using the analytical theory
of diffusion annealing formulated by Simpson & Sossin [2] and Schroeder [3]
taking into account the recent first-principles calculations of Fu et al. [4]
regarding the mobility of interstitials. Excellent agreement between theory and
experiment is obtained by a minimal set of adjustable parameters. The results
show that the diffusion annealing equations can be successfully employed for
the analysis of recovery experiments in iron.


title: Inverse Reinforcement Learning in Swarm Systems

abstract:
  Inverse reinforcement learning (IRL) has become a useful tool for learning
behavioral models from demonstration data. However, IRL remains mostly
unexplored for multi-agent systems. In this paper, we show how the principle of
IRL can be extended to homogeneous large-scale problems, inspired by the
collective swarming behavior of natural systems. In particular, we make the
following contributions to the field: 1) We introduce the swarMDP framework, a
sub-class of decentralized partially observable Markov decision processes
endowed with a swarm characterization. 2) Exploiting the inherent homogeneity
of this framework, we reduce the resulting multi-agent IRL problem to a
single-agent one by proving that the agent-specific value functions in this
model coincide. 3) To solve the corresponding control problem, we propose a
novel heterogeneous learning scheme that is particularly tailored to the swarm
setting. Results on two example systems demonstrate that our framework is able
to produce meaningful local reward models from which we can replicate the
observed global system dynamics.


title: Geometric Global Quantum Discord of Two-qubit States

abstract:
  We consider the geometric global quantum discord (GGQD) of two-qubit systems.
By analyzing the symmetry of geometric global quantum discord we give an
approach for deriving analytical formulae of the extremum problem which lies at
the core of computing the GGQD for arbitrary two-qubit states. Furthermore,
formulae of GGQD of arbitrary two-qubit states and some concrete examples are
presented.


title: Uniform quantized electron gas

abstract:
  In this work we study the correlation energy of the quantized electron gas of
uniform density at temperature $T=0$. To do so we utilize methods from
classical statistical mechanics. The basis for this is the Feynman path
integral for the partition function of quantized systems. With this
representation the quantum mechanical problem can be interpreted as, and is
equivalent to, a classical polymer problem in four dimensions where the fourth
dimension is imaginary time. Thus methods, results, and properties obtained in
the statistical mechanics of classical fluids can be utilized. From this
viewpoint we recover the well known RPA (random phase approximation). Then to
improve it we in this work modify the RPA by requiring the corresponding
correlation function to be such that electrons with equal spins can not be on
the same position. Numerical evaluations are compared with well known results
of a standard parameterization of Monte Carlo correlation energies.


title: On Stochastic Comparisons for Load-Sharing Series and Parallel Systems

abstract:
  We study the allocation strategies for redundant components in the
load-sharing series/parallel systems. We show that under the specified
assumptions, the allocation of a redundant component to the stochastically
weakest (strongest) component of a series (parallel) system is the best
strategy to achieve its maximal reliability. The results have been studied
under cumulative exposure model and for a general scenario as well. They have a
clear intuitive meaning, however, the corresponding additional assumptions are
not obvious, which can be seem from the proofs of our theorems


title:
Some Reliability Properties of Transformed-Transformer Family of
  Distributions

abstract:
  The Transformed-Transformer family of distributions are the resulting family
of distributions as transformed from a random variable $T$ through another
transformer random variable $X$ using a weight function $\omega$ of the
cumulative distribution function of $X$. In this paper, we study different
stochastic ageing properties, as well as different stochastic orderings of this
family of distributions. We discuss the results with several well known
distributions.


title: Heterogeneity Adjustment with Applications to Graphical Model Inference

abstract:
  Heterogeneity is an unwanted variation when analyzing aggregated datasets
from multiple sources. Though different methods have been proposed for
heterogeneity adjustment, no systematic theory exists to justify these methods.
In this work, we propose a generic framework named ALPHA (short for Adaptive
Low-rank Principal Heterogeneity Adjustment) to model, estimate, and adjust
heterogeneity from the original data. Once the heterogeneity is adjusted, we
are able to remove the biases of batch effects and to enhance the inferential
power by aggregating the homogeneous residuals from multiple sources. Under a
pervasive assumption that the latent heterogeneity factors simultaneously
affect a large fraction of observed variables, we provide a rigorous theory to
justify the proposed framework. Our framework also allows the incorporation of
informative covariates and appeals to the "Bless of Dimensionality". As an
illustrative application of this generic framework, we consider a problem of
estimating high-dimensional precision matrix for graphical model inference
based on multiple datasets. We also provide thorough numerical studies on both
synthetic datasets and a brain imaging dataset to demonstrate the efficacy of
the developed theory and methods.


title:
5th International Symposium on New Frontiers in Human-Robot Interaction
  2016 (NF-HRI 2016)

abstract:
  This volume is the proceedings of the 5th International Symposium on New
Frontiers in Human-Robot Interaction, held at the AISB Convention 2016, which
took place on the 5th and 6th of April 2016, in Sheffield, U.K.
  Organised by Maha Salem (Google U.K.), Astrid Weiss (Vienna University of
Technology, Austria), Paul Baxter (Lincoln University, U.K.), and Kerstin
Dautenhahn (University of Hertfordshire, U.K.).


title:
Modularity bounds for clusters located by leading eigenvectors of the
  normalized modularity matrix

abstract:
  Nodal theorems for generalized modularity matrices ensure that the cluster
located by the positive entries of the leading eigenvector of various
modularity matrices induces a connected subgraph. In this paper we obtain lower
bounds for the modularity of that set of nodes showing that, under certain
conditions, the nodal domains induced by eigenvectors corresponding to highly
positive eigenvalues of the normalized modularity matrix have indeed positive
modularity, that is they can be recognized as modules inside the network.
Moreover we establish Cheeger-type inequalities for the cut-modularity of the
graph, providing a theoretical support to the common understanding that highly
positive eigenvalues of modularity matrices are related with the possibility of
subdividing a network into communities.


title:
A high-redshift quasar absorber without CIV - a galactic outflow caught
  in the act?

abstract:
  We present a detailed analysis of a very unusual sub-damped Lyman alpha
(sub-DLA) system at redshift z=2.304 towards the quasar Q0453-423, based on
high signal-to-noise (S/N), high-resolution spectral data obtained with
VLT/UVES. With a neutral hydrogen column density of log N(HI)=19.23 and a
metallicity of -1.61 as indicated by [OI/HI] the sub-DLA mimics the properties
of many other optically thick absorbers at this redshift. A very unusual
feature of this system is, however, the lack of any CIV absorption at the
redshift of the neutral hydrogen absorption, although the relevant spectral
region is free of line blends and has very high S/N. Instead, we find high-ion
absorption from CIV and OVI in another metal absorber at a velocity more than
220km/s redwards of the neutral gas component. We explore the physical
conditions in the two different absorption systems using Cloudy photoionisation
models. We find that the weakly ionised absorber is dense and metal-poor while
the highly ionised system is thin and more metal-rich. The absorber pair
towards Q0453-423 mimics the expected features of a galactic outflow with
highly ionised material that moves away with high radial velocities from a
(proto)galactic gas disk in which star-formation takes place. We discuss our
findings in the context of CIV absorption line statistics at high redshift and
compare our results to recent galactic-wind and outflow models.


title:
Localization of dominant eigenpairs and planted communities by means of
  Frobenius inner products

abstract:
  We propose a new localization result for the leading eigenvalue and
eigenvector of a symmetric matrix $A$. The result exploits the Frobenius inner
product between $A$ and a given rank-one landmark matrix $X$. Different choices
for $X$ may be used, depending upon the problem under investigation. In
particular, we show that the choice where $X$ is the all-ones matrix allows to
estimate the signature of the leading eigenvector of $A$, generalizing previous
results on Perron-Frobenius properties of matrices with some negative entries.
As another application we consider the problem of community detection in graphs
and networks. The problem is solved by means of modularity-based spectral
techniques, following the ideas pioneered by Miroslav Fiedler in mid 70s. We
show that a suitable choice of $X$ can be used to provide new quality
guarantees of those techniques, when the network follows a stochastic block
model.


title:
New perspective on sampling-based motion planning via random geometric
  graphs

abstract:
  Roadmaps constructed by many sampling-based motion planners coincide, in the
absence of obstacles, with standard models of random geometric graphs (RGGs).
Those models have been studied for several decades and by now a rich body of
literature exists analyzing various properties and types of RGGs. In their
seminal work on optimal motion planning Karaman and Frazzoli (2011) conjectured
that a sampling-based planner has a certain property if the underlying RGG has
this property as well. In this paper we settle this conjecture and leverage it
for the development of a general framework for the analysis of sampling-based
planners. Our framework, which we call localization-tessellation, allows for
easy transfer of arguments on RGGs from the free unit-hypercube to spaces
punctured by obstacles, which are geometrically and topologically much more
complex. We demonstrate its power by providing alternative and (arguably)
simple proofs for probabilistic completeness and asymptotic (near-)optimality
of probabilistic roadmaps (PRMs). Furthermore, we introduce several variants of
PRMs, analyze them using our framework, and discuss the implications of the
analysis.


title:
Improving Students' Understanding of Quantum Mechanics by Using Peer
  Instruction Tools

abstract:
  Quantum mechanics is a challenging subject, even for advanced undergraduate
and graduate students. Here, we discuss the development and evaluation of
research-based concept tests for peer instruction as a formative assessment
tool in quantum mechanics (QM) courses. The preliminary evaluations show that
these tools are effective in helping students develop a good grasp of quantum
mechanics.


title:
DOA Parameter Estimation with 1-bit Quantization - Bounds, Methods and
  the Exponential Replacement

abstract:
  While 1-bit analog-to-digital conversion (ADC) allows to significantly reduce
the analog complexity of wireless receive systems, using the exact likelihood
function of the hard-limiting system model in order to obtain efficient
algorithms in the digital domain can make 1-bit signal processing challenging.
If the signal model before the quantizer consists of correlated Gaussian random
variables, the tail probability for a multivariate Gaussian distribution with N
dimensions (general orthant probability) is required in order to formulate the
likelihood function of the quantizer output. As a closed-form expression for
the general orthant probability is an open mathematical problem, formulation of
efficient processing methods for correlated and quantized data and an
analytical performance assessment have, despite their high practical relevance,
only found limited attention in the literature on quantized estimation theory.
Here we review the approach of replacing the original system model by an
equivalent distribution within the exponential family. For 1-bit signal
processing, this allows to circumvent calculation of the general orthant
probability and gives access to a conservative approximation of the receive
likelihood. For the application of blind direction-of-arrival (DOA) parameter
estimation with an array of K sensors, each performing 1-bit quantization, we
demonstrate how the exponential replacement enables to formulate a pessimistic
version of the Cram\'er-Rao lower bound (CRLB) and to derive an asymptotically
achieving conservative maximum-likelihood estimator (CMLE). The 1-bit DOA
performance analysis based on the pessimistic CRLB points out that a
low-complexity radio front-end design with 1-bit ADC is in particular suitable
for blind wireless DOA estimation with a large number of array elements
operating in the medium SNR regime.


title:
Effective irrationality measures for real and $p$-adic roots of rational
  numbers close to $1$, with an application to parametric families of
  Thue-Mahler equations

abstract:
  We show how the theory of linear forms in two logarithms allows one to get
effective irrationality measures for $n$-th roots of rational numbers ${a \over
b}$, when $a$ is very close to $b$. We give a $p$-adic analogue of this result
under the assumption that $a$ is $p$-adically very close to $b$, that is, that
a large power of $p$ divides $a-b$. As an application, we solve completely
certain families of Thue-Mahler equations. Our results illustrate, admittedly
in a very special situation, the strength of the known estimates for linear
forms in logarithms.


title: Equilibria of three constrained point charges

abstract:
  We study the critical points of Coulomb energy considered as a function on
configuration spaces associated with certain geometric constraints. Two
settings of such kind are discussed in some detail. The first setting arises by
considering polygons of fixed perimeter with freely sliding positively charged
vertices. The second one is concerned with triples of positive charges
constrained to three concentric circles. In each of these cases the Coulomb
energy is generically a Morse function. We describe the minima and other
stationary points of Coulomb energy and show that, for three charges, a
pitchfork bifurcation takes place accompanied by an effect of the Euler's
Buckling Beam type.


title: Complex solitons with real energies

abstract:
  Using Hirota's direct method and Baecklund transformations we construct
explicit complex one and two-solutions to the complex Korteweg-de Vries
equation, the complex modified Korteweg-de Vries equation and the complex
sine-Gordon equation. The one-soliton solutions of trigonometric and elliptic
type turn out to be PT-symmetric when a constant of integration is chosen to be
purely imaginary with one special choice corresponding to solutions recently
found by Khare and Saxena. We show that alternatively complex PT-symmetric
solutions to the Korteweg-de Vries equation may also be constructed
alternatively from real solutions to the modified Korteweg-de Vries by means of
Miura transformations. The multi-soliton solutions obtained from Hirota's
method break the PT-symmetric, whereas those obtained from Baecklund
transformations are PT-invariant under certain conditions. Despite the fact
that some of the Hamiltonian densities are non-Hermitian, the total energy is
found to be positive in all cases, that is irrespective of whether they are
PT-symmetric or not. The reason is that the symmetry can be restored by
suitable shifts in space-time and the fact that any of our N-soliton solutions
may be decomposed into N separate PT-symmetrizable one-soliton solutions.


title:
Strong suppression of shot noise in a feedback-controlled
  single-electron transistor

abstract:
  Feedback control of quantum mechanical systems is rapidly attracting
attention not only due to fundamental questions about quantum measurements but
also because of its novel applications in many fields in physics. Quantum
control has been studied intensively in quantum optics but recently progress
has been made in the control of solid-state qubits as well. In quantum
transport only a few active and passive feedback experiments have been realized
on the level of single-electrons, though theoretical proposals exist. Here we
demonstrate the suppression of shot noise in a single-electron transistor,
using an exclusively electronic closed-loop feedback to monitor and adjust the
counting statistics. With increasing feedback response we observe a stronger
suppression and faster freezing of charge current fluctuations. Our technique
is analog to the generation of squeezed light with in-loop photodetection as
used in quantum optics. Sub-Poisson single-electron sources will pave the way
for high precision measurements in quantum transport similar to its optical or
opto-mechanical equivalent.


title:
$C^1$ Quintic Splines on Domains Enclosed by Piecewise Conics and
  Numerical Solution of Fully Nonlinear Elliptic Equations

abstract:
  We introduce bivariate $C^1$ piecewise quintic finite element spaces for
curved domains enclosed by piecewise conics satisfying homogeneous boundary
conditions, construct local bases for them using Bernstein-B\'ezier techniques,
and demonstrate the effectiveness of these finite elements for the numerical
solution of the Monge-Amp\`ere equation over curved domains by B\"ohmer's
method.


title:
Clausius-Mossotti Lorentz-Lorenz relations and retardation effects for
  two-dimensional crystals

abstract:
  The macroscopic surface electric susceptibility determines the linear optical
properties of an insulating single-layer two-dimensional atomic crystal, and
can be expressed in terms of the microscopic polarizability of the atoms. We
compute the local electric field acting on a single atom, both for the static
and the dynamic case, as the superposition of the external applied electric
field and the fields generated by the induced dipoles in the crystal. We find
that, in the dynamic case, retardation effects dephase the local electric field
with respect to the incident one. This explains why the Fresnel coefficients of
a single-layer two-dimensional atomic crystal are intrinsically complex
quantities, even when a null macroscopic surface conductivity is assumed.


title: Directional Wavelet Bases Constructions with Dyadic Quincunx Subsampling

abstract:
  We construct directional wavelet systems that will enable building efficient
signal representation schemes with good direction selectivity. In particular,
we focus on wavelet bases with dyadic quincunx subsampling. In our previous
work, We show that the supports of orthonormal wavelets in our framework are
discontinuous in the frequency domain, yet this irregularity constraint can be
avoided in frames, even with redundancy factor less than 2. In this paper, we
focus on the extension of orthonormal wavelets to biorthogonal wavelets and
show that the same obstruction of regularity as in orthonormal schemes exists
in biorthogonal schemes. In addition, we provide a numerical algorithm for
biorthogonal wavelets construction where the dual wavelets can be optimized,
though at the cost of deteriorating the primal wavelets due to the intrinsic
irregularity of biorthogonal schemes.


title:
Pulsating hot O subdwarfs in Omega Cen: mapping a unique instability
  strip on the Extreme Horizontal Branch

abstract:
  We present an extensive survey for rapid pulsators among Extreme Horizontal
Branch (EHB) stars in omega Cen. The observations performed consist of nearly
100 hours of time-series photometry, as well as low-resolution spectroscopy. We
obtained photometry for some 300 EHB stars. Based on the spectroscopy, we
derive reliable values of log g, Teff and log(N(He)/N(H)) for 38 targets, as
well as estimates of the effective temperature for another nine targets. The
survey uncovered a total of five rapid variables with multi-periodic
oscillations between 85 and 125 s. Spectroscopically, they form a homogeneous
group of hydrogen-rich subdwarf O stars clustered between 48,000 and 54,000 K.
For each of the variables we are able to measure between two and three
significant pulsations believed to constitute independent harmonic
oscillations. In addition to the rapid variables, we found an EHB star with an
apparently periodic luminosity variation of ~2700 s, which we tentatively
suggest may be caused by ellipsoidal variations in a close binary. Using the
overlapping photometry and spectroscopy sample we are able to map an empirical
omega Cen instability strip. This can be directly compared to the pulsation
driving predicted from the Montreal "second-generation" models. We find that
the region where p-mode excitation occurs is bifurcated, and the well-known
instability strip between 29,000-36,000 K where the rapid subdwarf B pulsators
are found is complemented by a second one above 50,000 K. While significant
challenges remain at the quantitative level, we believe that the same
kappa-mechanism that drives the pulsations in hot B subdwarfs is also
responsible for the excitation of the rapid oscillations observed in the omega
Cen variables.


title: Robust Financial Bubbles

abstract:
  We study the concept of financial bubble in a market model endowed with a set
of probability measures, typically mutually singular to each other. In this
setting we introduce the notions of robust bubble and robust fundamental value
in a consistent way with the existing literature in the case a unique prior
exists. The notion of no dominance is also investigated under the uncertainty
framework. Finally, we provide concrete examples illustrating our results.


title: Siladi\'c's theorem: weighted words, refinement and companion

abstract:
  In a previous paper, the author gave a combinatorial proof and refinement of
Siladi\'c's theorem, a Rogers-Ramanujan type partition identity arising from
the study of Lie algebras. Here we use the basic idea of the method of weighted
words introduced by Alladi and Gordon to give a non-dilated version, further
refinement and companion of Siladi\'c's theorem. However, while in the work of
Alladi and Gordon, identities were proved by doing transformations on
generating functions, we use recurrences and $q$-difference equations as the
original method seems difficult to apply in our case. As the non-dilated
version features the same infinite product as Schur's theorem, another dilation
allows us to find a new interesting companion of Schur's theorem, with
difference conditions very different from the original ones.


title: Auxiliary Deep Generative Models

abstract:
  Deep generative models parameterized by neural networks have recently
achieved state-of-the-art performance in unsupervised and semi-supervised
learning. We extend deep generative models with auxiliary variables which
improves the variational approximation. The auxiliary variables leave the
generative model unchanged but make the variational distribution more
expressive. Inspired by the structure of the auxiliary variable we also propose
a model with two stochastic layers and skip connections. Our findings suggest
that more expressive and properly specified deep generative models converge
faster with better results. We show state-of-the-art performance within
semi-supervised learning on MNIST, SVHN and NORB datasets.


title: Special Operations Forces: A Global Immune System?

abstract:
  The use of special operations forces (SOF) in war fighting and peace keeping
efforts has increased dramatically in recent decades. A scientific
understanding of the reason for this increase would provide guidance as to the
contexts in which SOF can be used to their best effect. Ashby's law of
requisite variety provides a scientific framework for understanding and
analyzing a system's ability to survive and prosper in the face of
environmental challenges. We have developed a generalization of this law to
extend the analysis to systems that must respond to disturbances at multiple
scales. This analysis identifies a necessary tradeoff between scale and
complexity in a multiscale control system. As with Ashby's law, the framework
applies to the characterization of successful biological and social systems in
the context of complex environmental challenges. Here we apply this multiscale
framework to provide a control theoretic understanding of the historical and
increasing need for SOF, as well as conventional military forces. We propose
that the essential role distinction is in the separation between high
complexity fine scale challenges as opposed to large scale challenges. This
leads to a correspondence between the role SOF can best serve and that of the
immune system in complex organisms--namely, the ability to respond to
fine-grained, high-complexity disruptors and preserve tissue health. Much like
a multicellular organism, human civilization is composed of a set of distinct
and heterogeneous social tissues. Responding to disruption and restoring health
in a system with highly diverse local social conditions is an essentially
complex task. SOF have the potential to mitigate against harm without
disrupting normal social tissue behavior. This analysis suggests how SOF might
be leveraged to support global stability and mitigate against cascading crises.


title:
Quantum Reduced Loop Gravity and the foundation of Loop Quantum
  Cosmology

abstract:
  Quantum Reduced Loop Gravity is a promising framework for linking Loop
Quantum Gravity and the effective semiclassical dynamics of Loop Quantum
Cosmology. We review its basic achievements and its main perspectives,
outlining how it provides a quantum description of the Universe in terms of a
cuboidal graph which constitutes the proper framework for applying loop
techniques in a cosmological setting.


title: On concordances in 3-manifolds

abstract:
  We describe an action of the concordance group of knots in the three-sphere
on concordances of knots in arbitrary 3-manifolds. As an application we define
the notion of almost-concordance between knots. After some basic results, we
prove the existence of non-trivial almost-concordance classes in all
non-abelian 3-manifolds. Afterwards, we focus the attention on the case of lens
spaces, and use a modified version of the Ozsvath-Szabo-Rasmussen's
tau-invariant to obstruct almost-concordances and prove that each L(p,1) admits
infinitely many nullhomologous non almost-concordant knots. Finally we prove an
inequality involving the cobordism PL-genus of a knot and its tau-invariants.


title:
Which eligible assets are compatible with comonotonic capital
  requirements?

abstract:
  Within the context of capital adequacy, we study comonotonicity of risk
measures in terms of the primitives of the theory: acceptance sets and
eligible, or reference, assets. We show that comonotonicity cannot be
characterized by the properties of the acceptance set alone and heavily depends
on the choice of the eligible asset. In fact, in many important cases,
comonotonicity is only compatible with risk-free eligible assets. The
incompatibility with risky eligible assets is systematic whenever the
acceptability criterion is based on Value at Risk or any convex distortion risk
measure such as Expected Shortfall. These findings qualify and arguably call
for a critical appraisal of the meaning and the role of comonotonicity within a
capital adequacy context.


title: Convergence of Imprecise Continuous-Time Markov Chains

abstract:
  We study the limit behaviour of a generally non-linear ordinary differential
equation whose solution is a superadditive generalisation of a stochastic
matrix, and provide necessary and sufficient conditions for this solution to be
ergodic, in the sense that it converges to an operator that, essentially, maps
functions to constants. In the linear case, the solution of our differential
equation is equal to the matrix exponential of an intensity matrix and can then
be interpreted as the transition operator of a homogeneous continuous-time
Markov chain. Similarly, in the generalised non-linear case that we consider,
the solution can be interpreted as the lower transition operator of a specific
set of non-homogeneous continuous-time Markov chains, called an imprecise
continuous-time Markov chain. In this context, our main result provides a
necessary and sufficient condition for such an imprecise continuous-time Markov
chain to converge to a unique limiting distribution.


title: Using Spontaneous Emission of a Qubit as a Resource for Feedback Control

abstract:
  Persistent control of a transmon qubit is performed by a feedback protocol
based on continuous heterodyne measurement of its fluorescence. By driving the
qubit and cavity with microwave signals whose amplitudes depend linearly on the
instantaneous values of the quadratures of the measured fluorescence field, we
show that it is possible to stabilize permanently the qubit in any targeted
state. Using a Josephson mixer as a phase-preserving amplifier, it was possible
to reach a total measurement efficiency $\eta$=35%, leading to a maximum of 59%
of excitation and 44% of coherence for the stabilized states. The experiment
demonstrates multiple-input multiple-output analog Markovian feedback in the
quantum regime.


title:
Pilot Length Optimization for Spatially Correlated Multi-User MIMO
  Channel Estimation

abstract:
  We address the design of pilot sequences for channel estimation in the
context of multiple-user Massive MIMO; considering the presence of channel
correlation, and assuming that the statistics are known, we seek to exploit the
spatial correlation of the channels to minimize the length of the pilot
sequences, and specifically the fact that the users can be separated either
through their spatial signature (low-rank channel covariance matrices), or
through the use of different training sequences. We introduce an algorithm to
design short training sequences for a given set of user covariance matrices.
The obtained pilot sequences are in general non-orthogonal, however they ensure
that the channel estimation error variance is uniformly upper-bounded by a
chosen constant over all channel dimensions. We show through simulations using
a realistic scenario based on the one-ring channel model that the proposed
technique can yield pilot sequences of length significantly smaller than the
number of users in the system.


title: Improved Bounds on the Stretch Factor of $Y_4$

abstract:
  We establish an upper bound of 4.94 on the stretch factor of the Yao graph
$Y_4^\infty$ defined in the $L_\infty$-metric, improving upon the best
previously known upper bound of 6.31. We also establish an upper bound of 54.62
on the stretch factor of the Yao graph $Y_4$ defined in the Euclidean metric,
improving upon the best previously known upper bound of 662.16.


title: Investigating the QCD phase diagram with hadron multiplicities at NICA

abstract:
  We discuss the potential of the experimental programme at NICA to investigate
the QCD phase diagram and particularly the position of the critical line at
large baryon-chemical potential with accurate measurements of particle
multiplicities. We briefly review the present status and we outline the tasks
to be accomplished both theoretically and the experimentally to make hadronic
abundances a sensitive probe.