title:
Coupled harmonic oscillator in a multimode harmonic oscillator bath:
  Derivation of quantum propagator and master equation using white noise
  analysis

abstract:
  This paper presents an application of white noise functional approach to
derive the quantum propagator and the evolution of the reduced density matrix
for an open quantum system consisting of coupled harmonic oscillators which are
coupled to a bath consisting of a multimode harmonic oscillator. It is shown
that the full quantum propagator is a product of three individual propagators.
These propagators were obtained after two successive transformations of the
coordinates for the system, and the coordinates for the coupling between the
bath and one of the two harmonic oscillators in the system. The obtained
propagator is then used to derive the time evolution equation for the density
matrix describing the system. The method used to derive the propagator of the
open quantum system considered in this paper shows promise for analyzing open
quantum systems, due to its ease of use and mathematical rigor.


title: Top quark pair property measurements using the ATLAS detector at the LHC

abstract:
  Precise measurements of the properties of the top quark test the Standard
Model (SM) and can be used to constrain new physics models. The top quark pair
charge asymmetry is an asymmetry predicted to occur beyond leading-order QCD in
the SM, and may be significantly enhanced by the presence of new physics. The
$t\bar{t}$ production charge asymmetry is measured inclusively and
differentially using the 8 TeV ATLAS dataset in the lepton+jets final state,
including a dedicated measurement for highly boosted top quarks. The results
are in agreement with the SM and compared to new physics models. The top quark
is predicted in the SM to decay almost exclusively to a \textit{W} boson and
\textit{b} quark. Searches for non-SM top quark decays using the 8 TeV ATLAS
dataset, including $t \rightarrow qH$ and $t \rightarrow qZ$ are presented. In
addition, the measurement of the spin correlations in top quark pair production
using the polar angles distribution is discussed.


title:
Downlink Power Control for Massive MIMO Cellular Systems with Optimal
  User Association

abstract:
  This paper aims to minimize the total transmit power consumption for Massive
MIMO (multiple-input multiple-output) downlink cellular systems when each user
is served by the optimized subset of the base stations (BSs). We derive a lower
bound on the ergodic spectral efficiency (SE) for Rayleigh fading channels and
maximum ratio transmission (MRT) when the BSs cooperate using non-coherent
joint transmission. We solve the joint user association and downlink transmit
power minimization problem optimally under fixed SE constraints. Furthermore,
we solve a max-min fairness problem with user specific weights that maximizes
the worst SE among the users. The optimal BS-user association rule is derived,
which is different from maximum signal-to-noise-ratio (max-SNR) association.
Simulation results manifest that the proposed methods can provide good SE for
the users using less transmit power than in small-scale systems and that the
optimal user association can effectively balance the load between BSs when
needed.


title: On total domination in the Cartesian product of graphs

abstract:
  Ho proved in [A note on the total domination number, Util.Math. 77 (2008)
97--100] that the total domination number of the Cartesian product of any two
graphs with no isolated vertices is at least one half of the product of their
total domination numbers. We extend a result of Lu and Hou from [Total
domination in the Cartesian product of a graph and $K_2$ or $C_n$, Util. Math.
83 (2010) 313--322] by characterizing the pairs of graphs $G$ and $H$ for which
$\gamma_t(G\Box H)=\frac{1}{2}\gamma_t(G) \gamma_t(H)\,$, whenever
$\gamma_t(H)=2$. In addition, we present an infinite family of graphs $G_n$
with $\gamma_t(G_n)=2n$, which asymptotically approximate the equality in
$\gamma_t(G_n\Box G_n)\ge \frac{1}{2}\gamma_t(G_n)^2$.


title:
Neutrino Mass Generation and 750 GeV Diphoton excess via photon-photon
  fusion at the Large Hadron Collider

abstract:
  We propose a new model for explaining the diphoton excess observed at the
LHC. The uniqueness of our model is that this excess is being produced by
photon-photon induced sub-process. The model includes an isospin $3/2$ scalar
multiplet (having triply, doubly and singly charged scalars) at the electroweak
(EW) scale to explain the observed neutrino masses via the effective dimension
$7$ operator. The model also include a singlet scalar which is the di-photon
resonance. The loop induced coupling of the singlet scalar with a pair of
photons is enhanced due to contributions from multi-charged EW-scale scalars
(component of isospin $3/2$ multiplet) in the loop. We examine the production
of the singlet scalar at the LHC via photon-photon fusion sub-process and its
subsequent decay to di-photon. We found that a large part of parameter space of
the present model can explain the observed excess of di-photon events at the
LHC. We also study the other decay modes of the singlet scalar and the ensuing
predictions can be tested in the upcoming runs at the LHC.


title: Two-well atomic Bose-Hubbard analogues of optical cavities

abstract:
  We propose and analyse analogs of optical cavities for atoms using two-well
Bose-Hubbard models with pumping and losses. With one well pumped, we find that
both the mean-field dynamics and the quantum statistics show a quantitative
dependence on the choice of damped well. Both the systems we analyse remain far
from equilibrium, preserving good coherence between the wells in the
steady-state. We find a small degree of quadrature squeezing and mode
entanglement for some parameter regimes. Due to recent experimental advances,
it should be possible to demonstrate the effects we investigate and predict.


title:
Nonlinear Self-Interference Cancellation for Full-Duplex Radios: From
  Link- and System-Level Performance Perspectives

abstract:
  One of the promising technologies for LTE Evolution is full-duplex radio, an
innovation is expected to double the spectral efficiency. To realize
full-duplex in practice, the main challenge is overcoming self-interference,
and to do so, researchers have developed self-interference cancellation
techniques. Since most wireless transceivers use power amplifiers, especially
in cellular systems, researchers have revealed the importance of nonlinear
self-interference cancellation. In this article, we first explore several
nonlinear digital self-interference cancellation techniques. We then propose a
low complexity pre-calibration-based nonlinear digital self-interference
cancellation technique. Next we discuss issues about reference signal
allocation and the overhead of each technique. For performance evaluations, we
carry out extensive measurements through a real-time prototype and
link-/system-level simulations. For link-level analysis, we measure the amount
of cancelled self-interference for each technique. We also evaluate
system-level performances through 3D ray-tracing-based simulations. Numerical
results confirm the significant performance improvement over a half-duplex
system even in interference-limited indoor environments.


title:
The extended states in disordered 1D systems in the presence of the
  generalized $N$-mer correlations

abstract:
  We have been investigating the problem of the Anderson localization in a
disordered one dimensional tight-binding model. The disorder is created by the
interaction of mobile particles with other species, immobilized at random
positions. We introduce a novel method of creating correlations in the optical
lattices with such a kind of disorder by using two different lattices with
commensurate lattice lengths to hold two species of the particles. Such a
model, called the generalized random $N$-mer model leads to the appearance of
multiple extended states in contrary to a localization of all states usually
expected in one dimension. We develop a method, based on properties of transfer
matrices which can be used to determine the presence of extended states and
their energies for that class of correlations. Analytical results are compared
with the numerical calculations for several cases which can be realized in
cold-atom experiments.


title:
Computation of Higher-Order Moments of Generalized Polynomial Chaos
  Expansions

abstract:
  Because of the complexity of fluid flow solvers, non-intrusive uncertainty
quantification techniques have been developed in aerodynamic simulations in
order to compute the quantities of interest required in an optimization
process, for example. The objective function is commonly expressed in terms of
moments of these quantities, such as the mean, standard deviation, or even
higher-order moments. Polynomial surrogate models based on polynomial chaos
expansions have often been implemented in this respect. The original approach
of uncertainty quantification using polynomial chaos is however intrusive. It
is based on a Galerkin-type formulation of the model equations to derive the
governing equations for the polynomial expansion coefficients. Third-order,
indeed fourth-order moments of the polynomials are needed in this analysis.
Besides, both intrusive and non-intrusive approaches call for their computation
provided that higher-order moments of the quantities of interest need be
post-processed. In most applications they are evaluated by Gauss quadratures,
and eventually stored for use throughout the computations. In this paper
analytical formulas are rather considered for the moments of the continuous
polynomials of the Askey scheme, so that they can be evaluated by
quadrature-free procedures instead. Matlab codes have been developed for this
purpose and tested by comparisons with Gauss quadratures.


title:
Additional aspects of the generalized linear-fractional branching
  process

abstract:
  We derive some additional results on the Bienyam\'e-Galton-Watson branching
process with $\theta -$linear fractional branching mechanism, as studied in
\cite{Sag}. This includes: the explicit expression of the limit laws in both
the sub-critical cases and the super-critical cases with finite mean, the
long-run behavior of the population size in the critical case, limit laws in
the super-critical cases with infinite mean when the $\theta $-process is
either regular or explosive, results regarding the time to absorption, an
expression of the probability law of the $\theta $-branching mechanism
involving Bell polynomials, the explicit computation of the stochastic
transition matrix of the $\theta -$process, together with its powers.


title:
Hidden quantum phase transition in Mn$_{1-x}$Fe$_{x}$Ge: evidence
  brought by small-angle neutron scattering

abstract:
  The magnetic system of the Mn$_{1-x}$Fe$_{x}$Ge solid solution is ordered in
a spiral spin structure in the whole concentration range of $x \in [0 \div 1]$.
The close inspection of the small-angle neutron scattering data reveals the
quantum phase transition from the long-range ordered (LRO) to short range
ordered (SRO) helical structure upon increase of Fe-concentration at $x \in
[0.25 \div 0.4]$. The SRO of the helical structure is identified as a
Lorentzian contribution, while LRO is associated with the Gaussian contribution
into the scattering profile function. The scenario of the quantum phase
transition with $x$ as a driving parameter is similar to the thermal phase
transition in pure MnGe. The quantum nature of the SRO is proved by the
temperature independent correlation length of the helical structure at low and
intermediate temperature ranges with remarkable decrease above certain
temperature $T_Q$. We suggest the $x$-dependent modification of the effective
Ruderman-Kittel-Kasuya-Yosida exchange interaction within the Heisenberg model
of magnetism to explain the quantum critical regime in Mn$_{1-x}$Fe$_{x}$Ge.


title: Warped extra dimension and inclined events at Pierre Auger Observatory

abstract:
  The generalized solution for the warp factor of the Randall-Sundrum metric is
presented which is symmetric with respect to both branes and explicitly
periodic in extra variable. Given that the curvature of the 5-dimensional
space-time is small, the expected rate of neutrino-induced inclined events at
the Surface Detector of the Pierre Auger Observatory is calculated. Both the
"downward-going" (DG) and "Earth-skimming" (ES) neutrinos are considered. By
comparing the expected event rate with the recent Auger data on searching for
neutrino candidates, the lower bound on the fundamental gravity scale M_5 is
obtained. The ratio of the number of the ES air showers to the number of the DG
showers is estimated as a function of M_5.


title:
Melting of Wigner crystal in high-mobility $n$-GaAs/AlGaAs
  heterostructures at filling factors $0.18 > \nu > 0.125$: Acoustic studies

abstract:
  Using acoustic methods the complex high-frequency conductance of
high-mobility $n$-GaAs/AlGaAs heterostructures was determined in magnetic
fields 12$\div$18~T. Based on the observed frequency and temperature
dependences we conclude that in the investigated magnetic field range and at
sufficiently low temperatures, $T \lesssim 200$~mK, the electron system forms a
Wigner crystal deformed due to pinning by disorder. At some temperature, which
depends on the electron filling factor, the temperature dependences of both
components of the complex conductance get substantially changed. We have
ascribed this rapid change of the conduction mechanism to melting of the Wigner
crystal and study the dependence of the so-defined melting temperature on the
electron filling factor.


title:
Giant perpendicular magnetic anisotropy energies in CoPt thin films:
  Impact of reduced dimensionality and imperfections

abstract:
  The impact of reduced dimensionality on the magnetic properties of the
tetragonal L1$_{0}$ CoPt alloy is investigated from ab-initio considering
several kinds of surface defects. By exploring the dependence of the
magnetocrystalline anisotropy energy (MAE) on the thickness of CoPt thin films,
we demonstrate the crucial role of the chemical nature of the surface. For
instance, Pt-terminated thin films exhibit huge MAEs which can be 1000% larger
than those of Co-terminated films. Besides the perfect thin films, we
scrutinize the effect of defective surfaces such as stacking faults or
anti-sites on the surface layers. Both types of defects reduce considerably the
MAE with respect to the one obtained for Pt-terminated thin films. A detailed
analysis of the electronic structure of the thin films is provided with a
careful comparison to the CoPt bulk case. The behavior of the MAEs is then
related to the location of the different virtual bound states utilising second
order perturbation theory.


title:
Complete classification of the torsion structures of rational elliptic
  curves over quintic number fields

abstract:
  We classify the possible torsion structures of rational elliptic curves over
quintic number fields. In addition, let E be an elliptic curve defined over Q
and let G = E(Q)_tors be the associated torsion subgroup. We study, for a given
G, which possible groups G \subseteq H could appear such that H=E(K)_tors, for
[K:Q]=5. In particular, we prove that at most there is a quintic number field K
such that E(Q)_tors\neq E(K)_tors.


title:
Multi-step atomic reaction enhanced by an atomic force microscope probe
  on Si(111) and Ge(111) surfaces

abstract:
  We present first-principles total-energy electronic-structure calculations
that provide the microscopic mechanism of the adatom interchange reaction on
the Sn- and Pb-covered Ge(111)-(2x8) and the Sb-covered Si(111)-(7x7) surfaces
with and without the tip of the atomic force microscope (AFM). We find that,
without the presence of the AFM tip on the Ge surface, the adatom interchange
occurs through the migration of the adatom, the spontaneous formation of the
dimer structures of the two adatoms, the dimer-dimer structural transitions
that induce the exchange of the positions of the two adatoms, and then the
backward migration of the adatom. We also find that the dimer structure is
unfeasible at room temperature on the Si surface and the adatom interchange are
hereby unlikely. With the presence of the tip, we find that the reaction
pathways are essentially the same for the Ge surface but that the energy
barriers of the migration and the exchange processes are substantially reduced
by the AFM tip. We further find that the AFM tip induces the spontaneous
formation of the dimer structure even on the Si surface, hereby opening a
channel of the interchange of the adatoms. Our calculations show that the bond
formation between the AFM tip atom and the surface adatom is essential for the
atom manipulation using the AFM tip.


title:
Logarithmic enhancements in conformal perturbation theory and their real
  time interpretation

abstract:
  We study various corrections of correlation functions to leading order in
conformal perturbation theory, both on the cylinder and on the plane. Many
problems on the cylinder are mathematically equivalent to those in the plane if
we give the perturbations a position dependent scaling profile. The integrals
to be done are then similar to the study of correlation functions with one
additional insertion at the center of the profile. We will be primarily
interested in the divergence structure of these corrections when computed in
dimensional regularization. In particular, we show that the logarithmic
divergences (enhancements) that show up in the plane under these circumstances
can be understood in terms of resonant behavior in time dependent perturbation
theory, for a transition between states that is induced by an oscillatory
perturbation on the cylinder.


title:
Multiple positive solutions for a class of Kirchhoff type problems
  involving general critical growth

abstract:
  In this paper, we study the following nonlinear Kirchhoff problem involving
critical growth: $$ \left\{% \begin{array}{ll} -(a+b\int_{\Omega}|\nabla
u|^2dx)\Delta u=|u|^4u+\lambda|u|^{q-2}u, u=0\ \ \text{on}\ \ \partial\Omega,
\end{array}% \right. $$ where $1<q<2$, $\lambda,\ a,\ b>0$ are parameters and
$\Omega$ is a bounded domain in $\R^3$. We prove that there exists
$\lambda_1=\lambda_1(q,\Omega)>0$ such that for any $\lambda\in(0,\lambda_1)$
and $a,\ b>0$, the above Kirchhoff problem possesses at least two positive
solutions and one of them is a positive ground state solution. We also
establish the convergence property of the ground state solution as the
parameter $b\searrow 0$. More generally, we obtain the same results about the
following Kirchhoff problem: $$ \left\{% \begin{array}{ll}
-(a+b\int_{\mathbb{R}^3}|\nabla u|^2dx)\Delta
u+u=Q(x)|u|^4u+{\lambda}f(x)|u|^{q-2}u, u\in H^1(\mathbb{R}^3), \end{array}%
\right. $$ for any $a,\ b>0$ and $\lambda\in \big(0,\lambda_0(q,Q,f)\big)$
under certain conditions of $f(x)$ and $Q(x)$. Finally, we investigate the
depending relationship between $\lambda_0$ and $b$ to show that for any (large)
$\lambda>0$, there exists a $b_0(\lambda)>0$ such that the above results hold
when $b>b_0(\lambda)$ and $a>0$.


title:
Intra-cluster Characteristics of 28 GHz Wireless Channel in Urban Micro
  Street Canyon

abstract:
  This paper investigates intra-cluster channel characteristics of non
line-of-sight (NLOS) 28 GHz channels in street canyon scenarios. These channel
characteristics include cluster numbers, number of subpaths within each
cluster, intra-cluster delay spreads, and intra-cluster angular spreads. Both
measurement and ray tracing results are presented and compared. Furthermore,
distribution fittings are performed and models and parameters for different
intra-cluster channel characteristics are proposed.


title: Metastability of non-reversible mean-field Potts model with three spins

abstract:
  We examine a non-reversible, mean-field Potts model with three spins on a set
with $N\uparrow\infty$ points. Without an external field, there are three
critical temperatures and five different metastable regimes. The analysis can
be extended by a perturbative argument to the case of small external fields. We
illustrate the case of large external fields with some phenomena which are not
present in the absence of external field.


title: Torsional Newton-Cartan Geometry from the Noether Procedure

abstract:
  We apply the Noether procedure for gauging space-time symmetries to theories
with Galilean symmetries, analyzing both massless and massive (Bargmann)
realizations. It is shown that at the linearized level the Noether procedure
gives rise to (linearized) torsional Newton-Cartan geometry. In the case of
Bargmann theories the Newton-Cartan form $M_\mu$ couples to the conserved mass
current. We show that even in the case of theories with massless Galilean
symmetries it is necessary to introduce the form $M_\mu$ and that it couples to
a topological current. Further, we show that the Noether procedure naturally
gives rise to a distinguished affine (Christoffel type) connection that is
linear in $M_\mu$ and torsionful. As an application of these techniques we
study the coupling of Galilean electrodynamics to TNC geometry at the
linearized level.


title:
Lateral pressure profile in lipid membranes with finite curvature and
  mechanosensitive channel gating

abstract:
  This review describes the analytical calculation of lateral pressure profile
in lipid membrane with finite curvature. The derivation is based on the
previously developed microscopic model of flexible strings [1,2]. According to
this theory the energy per unit chain is considered as energy of flexible
string (Euler's elastic beam of finite thickness) and interaction between
chains is considered as an entropic repulsion. This microscopic theory allows
to obtain expression for lateral pressure distribution in bent lipid membrane
if treating a bending as a small deviation from the flat membrane conformation
and using perturbation theory with small parameter L0J, where L0 is the
monolayer thickness, J is mean curvature of membrane. Because lateral pressure
distribution is related to the elastic properties of lipid bilayer [3] then
first spontaneous moment of lateral pressure and the expression for bending
modulus may be derived from this theoretical model. Finally, based on
analytical expression for the lateral pressure distribution in bent lipid
membrane one can obtain analytically the energy difference between two states
of mechanosensitive channel, particularly MscL [4, 5, 6]. Calculated expression
depends on inter-facial surface tension, the channel area change in region
between hydrophobic interior and the aqueous surroundings and the bending
modulus and spontaneous bending moment values.


title:
Erratum for "Axion Dark Matter Coupling to Resonant Photons via Magnetic
  Field" [arXiv:1512.05547]

abstract:
  A recent comment highlights a discussion at the PATRAS Workshop on Axions,
WIMPs and WISPs relating to a recent publication. We respond to this comment,
and detail a calculation error in the original letter.


title:
One-loop omega-potential of charged massive particles in a constant
  homogeneous magnetic field at high temperatures

abstract:
  The explicit expressions for the high-temperature expansions of the one-loop
corrections to the omega-potential coming from charged scalar and Dirac
particles and, separately, from antiparticles in a constant homogeneous
magnetic field are derived. The explicit expressions for the non-perturbative
corrections to the effective action at finite temperature and density are
obtained. Thermodynamic properties of a gas of charged scalars in a constant
homogeneous magnetic field are analyzed in the one-loop approximation. It turns
out that, in this approximation, the system suffers a first-order phase
transition from the diamagnetic to the superconducting state at sufficiently
high densities. The improvement of the one-loop result by summing the ring
diagrams is investigated. This improvement leads to a drastic change in
thermodynamic properties of the system. The gas of charged scalars passes to
the ferromagnetic state in place of the superconducting one at high densities
and sufficiently low temperatures, in the high temperature regime.


title:
Spin squeezing and Quantum Fisher Information in the Jaynes-Cummings
  Dicke Model

abstract:
  We investigate spin squeezing (SS) and the quantum Fisher information (QFI)
for the Jaynes-Cummings Dicke (JC-Dicke) model in a two component atomic
Bose-Einstein condensate (BEC) inside an optical cavity. Analytical expressions
for spin squeezing and the reciprocal of the quantum Fisher information per
particle (RMQFI) are derived using the frozen spin approximation. It is shown
that in the superradiant phase near the critical point, maximum squeezing and
maximum quantum entanglement occurs. The present study is relevant to quantum
information processing and precision spectroscopy.


title:
Template matching method for the analysis of interstellar cloud
  structure

abstract:
  The structure of interstellar medium can be characterised at large scales in
terms of its global statistics (e.g. power spectra) and at small scales by the
properties of individual cores. Interest has been increasing in structures at
intermediate scales, resulting in a number of methods being developed for the
analysis of filamentary structures. We describe the application of the generic
template-matching (TM) method to the analysis of maps. Our aim is to show that
it provides a fast and still relatively robust way to identify elongated
structures or other image features. We present the implementation of a TM
algorithm for map analysis. The results are compared against rolling Hough
transform (RHT), one of the methods previously used to identify filamentary
structures. We illustrate the method by applying it to Herschel surface
brightness data. The performance of the TM method is found to be comparable to
that of RHT but TM appears to be more robust regarding the input parameters,
for example, those related to the selected spatial scales. Small modifications
of TM enable one to target structures at different size and intensity levels.
In addition to elongated features, we demonstrate the possibility of using TM
to also identify other types of structures. The TM method is a viable tool for
data quality control, exploratory data analysis, and even quantitative analysis
of structures in image data.


title:
Probing Transverse Momentum Broadening via Dihadron and Hadron-jet
  Angular Correlations in Relativistic Heavy-ion Collisions

abstract:
  Dijet, dihadron, hadron-jet angular correlations have been reckoned as
important probes of the transverse momentum broadening effects in relativistic
nuclear collisions. When a pair of high-energy jets created in hard collisions
traverse the quark-gluon plasma produced in heavy-ion collisions, they become
de-correlated due to the vacuum soft gluon radiation associated with the
Sudakov logarithms and the medium-induced transverse momentum broadening. For
the first time, we employ the systematical resummation formalism and establish
a baseline calculation to describe the dihadron and hadron-jet angular
correlation data in $pp$ and peripheral $AA$ collisions where the medium effect
is negligible. We demonstrate that the medium-induced broadening $\langle
p_\perp^2\rangle$ and the so-called jet quenching parameter $\hat q$ can be
extracted from the angular de-correlations observed in $AA$ collisions. A
global $\chi^2$ analysis of dihadron and hadron-jet angular correlation data
renders the best fit $\langle p_\perp^2 \rangle \sim 13~\textrm{GeV}^2$ for a
quark jet at RHIC top energy. Further experimental and theoretical efforts
along the direction of this work shall significantly advance the quantitative
understanding of transverse momentum broadening and help us acquire
unprecedented knowledge of jet quenching parameter in relativistic heavy-ion
collisions.


title:
Bounds on the Conformal Scale of a Minimally Coupled Dilaton and
  Multi-Leptonic Signatures at the LHC

abstract:
  We explore the potential for the discovery of a dilaton
$\mathcal{O}(200-500)$ GeV in a classical scale/conformal invariant extension
of the Standard Model by investigating the size of the corresponding breaking
scale $\Lambda$ at the LHC, extending a previous analysis. In particular, we
address the recent bounds on $\Lambda$ derived from Higgs boson searches. We
investigate if such a dilaton can be produced via gluon-gluon fusion,
presenting rates for its decay either into a pair of Higgs bosons or into two
heavy gauge bosons, which can give rise to multi-leptonic final states. A
detailed analysis via PYTHIA-FastJet has been carried out of the dominant
Standard Model backgrounds, at a centre of mass energy of 14 TeV. We show that
early data of $\sim 20$ fb$^{-1}$ can certainly probe the region of parameter
space where such a dilaton is allowed. A conformal scale of 5 TeV is allowed by
the current data, for almost all values of the dilaton mass investigated.


title: Completeness of general pp-wave spacetimes and their impulsive limit

abstract:
  We investigate geodesic completeness in the full family of pp-wave or
Brinkmann spacetimes in their extended as well as in their impulsive form. This
class of geometries contains the recently studied gyratonic pp-waves, modelling
the exterior field of a spinning beam of null particles, as well as NPWs, which
generalise classical pp-waves by allowing for a general wave surface. The
problem of geodesic completeness reduces to the question of completeness of
trajectories on a Riemannian manifold under an external force field. Building
upon respective recent results we derive completeness criteria in terms of the
spatial asymptotics of the profile function in the extended case. In the
impulsive case we use a fixed point argument to show that irrespective of the
behaviour of the profile function all geometries in the class are complete.


title:
Universal Random Access Error Exponents for Codebooks of Different
  Word-Lengths

abstract:
  Csisz\'ar's channel coding theorem for multiple codebooks is generalized
allowing the codeword lenghts differ across codebooks. Also in this case, for
each codebook an error exponent can be achieved that equals the random coding
exponent for this codebook alone, in addition, erasure detection failure
probability tends to 0. This is proved even for sender and receiver not knowing
the channel. As a corollary, a substantial improvement is obtained when the
sender knows the channel.


title: Cracking Down on Fake Photons - A Case of 750 GeV Diphoton Resonance -

abstract:
  Among various models to explain the $750$ GeV diphoton resonance hinted at
the LHC Run 2, a class of models where the resonance decays not into a pair of
photons but into a pair of photon-jets is gathering definite attention. In this
paper, we study how well we can distinguish the di-photon-jet resonance from
the diphoton resonance by examining detector responses to the photon-jets. We
find that the sum of $p_T$ of the first $e^+e^-$ pair from the photon
conversion provides strong discrimination power. We also discuss determination
of the lifetime of the light intermediate particle by measuring the photon
conversion points.


title: On the curious series related to the elliptic integrals

abstract:
  By using the theory of the elliptic integrals a new method of summation is
proposed for a certain class of series and their derivatives involving
hyperbolic functions. It is based on the termwise differentiation of the series
with respect to the elliptic modulus and integral representations of several of
the series in terms of the inverse Mellin transforms related to the Riemann
zeta function. The relation with the corresponding case of the Voronoi
summation formula is exhibited. The involved series are expressed in closed
form in terms of complete elliptic integrals of the first and second kind, and
some special cases are calculated in terms of particular values of the Euler
gamma function.


title:
Calculation of x-ray scattering patterns from nanocrystals at high x-ray
  intensity

abstract:
  We present a generalized method to describe the x-ray scattering intensity of
the Bragg spots in a diffraction pattern from nanocrystals exposed to intense
x-ray pulses. Our method involves the subdivision of a crystal into smaller
units. In order to calculate the dynamics within every unit we employ a
Monte-Carlo (MC)-molecular dynamics (MD)-ab-initio hybrid framework using real
space periodic boundary conditions. By combining all the units we simulate the
diffraction pattern of a crystal larger than the transverse x-ray beam profile,
a situation commonly encountered in femtosecond nanocrystallography experiments
with focused x-ray free-electron laser radiation. Radiation damage is not
spatially uniform and depends on the fluence associated with each specific
region inside the crystal. To investigate the effects of uniform and
non-uniform fluence distribution we have used two different spatial beam
profiles, gaussian and flattop.


title: Cyclic vs mixed homology

abstract:
  The spectral theory of the Karoubi operator due to Cuntz and Quillen is
extended to general mixed (duchain) complexes, that is, chain complexes which
are simultaneously cochain complexes. Connes' coboundary map B can be viewed as
a perturbation of the noncommutative De Rham differential d by a polynomial in
the Karoubi operator. The homological impact of such perturbations is expressed
in terms of two short exact sequences.


title: Time symmetry in wave function collapse

abstract:
  The notion of a physical collapse of the wave function is embodied in
dynamical collapse models. These involve a modification of the unitary
evolution of the wave function such as to give a dynamical account of collapse.
The resulting dynamics is at first sight time asymmetric for the simple reason
that the wave function depends on those collapse events in the past but not
those in the future. Here we show that dynamical wave function collapse models
admit a general description that has no inbuilt direction of time. Given some
simple constraints, we show that there exist empirically equivalent pictures of
collapsing wave functions in both time directions, each satisfying the same
dynamical rules. A preferred direction is singled out only by the asymmetric
initial and final time constraints on the state of the Universe.


title: A "LHC Premium" for Early Career Researchers? Perceptions from within

abstract:
  More than 36,000 students and post-docs will be involved in experiments at
the Large Hadron Collider (LHC) until 2025. Do they expect that their learning
experience will have an impact on their professional future? By drawing from
earlier salary expectations literature, this paper proposes a framework aiming
at explaining the professional expectations of early career researchers (ECR)
at the LHC. Results from different ordered logistic models suggest that
experiential learning at LHC positively correlates with both current and former
students' salary expectations. At least two not mutually exclusive explanations
underlie such a relationship. First, the training at LHC gives early career
researchers valuable expertise, which in turn affects salary expectations;
secondly, respondents recognise that the LHC research experience per se may act
as a signal in the labour market. Respondents put a price tag on their
experience at LHC, a "salary premium" ranging from 5% to 12% in terms of future
salaries compared with what they would have expected without such experience.


title:
Decentralised Resource Allocation and Coordination for 5G Cellular
  Communication Networks

abstract:
  In order to cope with the ever increasing traffic load that networks will
need to support, a new approach for planning cellular networks deployments
should be followed. Traditionally, cell association and resource allocation has
been based on the received signal power but this approach seems to be
inadequate regarding the brewing of heterogeneous networks. In this work, we
first implement a network simulator in order to test new cell associacion and
resource allocation techniques. Then, we pose the network utility maximisation
problem, reformulating the Downlink and Uplink Decoupling (DUDe) scheme under
the framework and tools of mathematical optimisation. We derive the explicit
solution of the problem under fixed and non-fixed association policy so as to
propose and develope both centralised and decentralised algorithms capable of
solving cell association and resource allocation problems. We observe that the
decentralised approach requires low computational effort and represents a
significant gain in the overall performance of the network.


title: The warm absorber in the radio-loud quasar 4C +74.26

abstract:
  Outflows of photoionized gas are commonly detected in the X-ray spectra of
Seyfert 1 galaxies. However, the evidence for this phenomenon in broad line
radio galaxies, which are analogous to Seyfert 1 galaxies in the radio-loud
regime, has so far been scarce. Here, we present the analysis of the X-ray
absorption in the radio-loud quasar 4C +74.26. With the aim of characterizing
the kinetic and the ionization conditions of the absorbing material, we fitted
jointly the XMM-Newton Reflection Grating Spectrometer (RGS) and the Chandra
High Energy Transmission Grating Spectrometer (HETGS) spectra, which were taken
4 months apart. The intrinsic continuum flux did not vary significantly during
this time lapse. The spectrum shows the absorption signatures (e.g., Fe-UTA,
\ion{O}{vii}, and \ion{Ne}{vii}--\ion{Ne}{x}) of a photoionized gas outflow
($N_{\rm H} \sim 3.5 \times 10^{21} \rm cm^{-2}$, $\log \xi \sim 2.6$, $v_{\rm
out}\sim 3600 \, \rm km \, s^{-1}$) located at the redshift of source. We
estimate that the gas is located outside the broad line region but within the
boundaries of the putative torus. This ionized absorber is consistent with the
X-ray counterpart of a polar scattering outflow reported in the optical band
for this source. The kinetic luminosity carried by the outflow is insufficient
to produce a significant feedback is this quasar. Finally, we show that the
heavy soft X-ray absorption that was noticed in the past for this source arises
mostly in the Galactic ISM.


title: Phase transition of social learning collectives and "Echo chamber"

abstract:
  An "Echo chamber" is the state of social learning agents whose performances
are deteriorated by excessive observation of others. We understand this to be
the collective behavior of agents in a restless multi-armed bandit. The bandit
has $M$ good levers and bad levers. A good lever changes to a bad one randomly
with probability $q_{C}$ and a new good lever appears. $N$ agents exploit ones'
lever if they know that it is a good one. Otherwise, they search for a good one
by (i) random search (success probability $q_{I}$) and (ii) observe a good
lever that is known by other agents (success probability $q_{O}$) with
probability $1-p$ and $p$, respectively. The distribution of agents in good
levers obeys the Yule distribution with power law exponent $1+\gamma$ in the
limit $N,M\to \infty$ and $\gamma=1+\frac{(1-p)q_{I}}{pq_{O}}$. The expected
value of the number of the agents with a good lever $N_{1}$ increases with $p$.
The system shows a phase transition at $p_{c}=\frac{q_{I}}{q_{I}+q_{o}}$. For
$p<p_{c}\,(>p_{c})$, the variance of $N_{1}$ per agent $\mbox{Var}(N_{1})/N$ is
finite (diverges as $\propto N^{2-\gamma}$ with $N$). There is a threshold
value $N_{s}$ for the system size that scales as $\ln N_{s} \propto
1/(\gamma-1)$. For $p>p_{c}$ and $N<N_{s}$, all agents tend to share only one
good lever. $\mbox{E}(N_{1})$ decreases to zero as $p\to 1$, which is referred
to as the "Echo chamber".


title:
Analyzing the equilibrium states of quasi-neutral spatially
  inhomogeneous system of charges above liquid dielectric film basing on first
  principles of quantum statistics

abstract:
  The theory of quasi-neutral equilibrium states of charges above liquid
dielectric surface is built. This theory is based on first principles of
quantum statistics for systems, comprising many identical particles. The
proposed approach is concerned with applying the variation principle, modified
for the considered systems, and the Thomas-Fermi model. In terms of the
developed theory a self-consistency equations are obtained. These equations
provide the relation between the main parameters, describing the system: the
potential of static electric field, the distribution function of charges and
the surface profile of liquid dielectric. The equations are used to study the
phase transition in the system to a spatially periodic state. The proposed
method can be applied to analyzing the properties of the phase transition in
the system to a spatially periodic states of wave type. Using the analytical
and numerical methods, we make a detailed research of the dependence of
critical parameters of such phase transition on the thickness of liquid
dielectric film. Some stability criteria of the new asymmetric phase of the
studied system are discussed.


title: Geometry and space-time extent of pion emission region at FCC energies

abstract:
  The energy dependence is investigated for a wide set of space-time
characteristics derived from Bose - Einstein correlations of secondary pion
pairs produced in proton-proton and nucleus-nucleus interactions. Analytic
functions suggested for smooth approximations of the energy dependence of
emission region parameters demonstrate reasonable agreement with all available
experimental results for proton-proton collisions while the approximations
correspond to most of experimental data for nucleus-nucleus collisions at
energies above 5 GeV. Estimations for a wide set of space-time quantities are
obtained for energies for the Future Circular Collider (FCC) project based on
the smooth approximations. The space particle densities at freeze-out are
derived also from estimations for the volume of the emission region and for
total multiplicity at FCC energies. Estimations for charged particle density
and its critical value allow the possibility of lasing behavior for secondary
pions in nucleus-nucleus collisions at FCC energy. The mathematical formalism
is presented for study of the peak shape of correlation function for general
case of central-symmetrical Levy - Feldheim distribution.


title: Global parameter test ideals

abstract:
  This paper shows the existence of ideals whose localizations and completions
at prime ideals are parameter test ideals of the localized and completed rings.
We do this for Cohen-Macaulay localizations (resp., completions) of non-local
rings, for generalized Cohen-Macaulay rings, and for non-local rings with
isolated non Cohen-Macaulay points, each being an isolated non $F$-rational
point. The tools used to prove this results are constructive in nature and as a
consequence our results yield algorithms for the computation of these global
parameter test ideals.
  Finally, we illustrate the power of our methods by analyzing the HSL numbers
of local cohomology modules with support at any prime ideal.


title:
Novel Performance Analysis of Network Coded Communications in
  Single-Relay Networks

abstract:
  In this paper, we analyze the performance of a single-relay network in which
the reliability is provided by means of Random Linear Network Coding (RLNC). We
consider a scenario when both source and relay nodes can encode packets. Unlike
the traditional approach to relay networks, we introduce a passive relay mode,
in which the relay node simply retransmits collected packets in case it cannot
decode them. In contrast with the previous studies, we derive a novel
theoretical framework for the performance characterization of the considered
relay network. We extend our analysis to a more general scenario, in which
coding coefficients are generated from non-binary fields. The theoretical
results are verified using simulation, for both binary and non-binary fields.
It is also shown that the passive relay mode significantly improves the
performance compared with the active-only case, offering an up to two-fold gain
in terms of the decoding probability. The proposed framework can be used as a
building block for the analysis of more complex network topologies.


title: Higgs boson mass from gauge invariant operators

abstract:
  We make the assumption that the vacuum correlators of the gauge invariant
kinetic term of the Higgs doublet are the same before and after the spontaneous
symmetry breaking of the theory. Based on this we determine the mass of the
standard model Higgs boson at $m_h \approx 125.07$ GeV by considering one loop
and the most relevant two loop corrections. This result might suggest that
there is a single Higgs boson doublet that contributes to the electroweak
symmetry breaking.


title: On Locally Symmetric $3$-Dimensional Riemannian Lie Groups

abstract:
  In this paper, we use the powerful tool Milnor bases to classify all the
$3-$dimensional connected and locally symmetric Riemannian Lie Groups by
solving system of polynomial equations of structure constants of each Lie
algebra . Moreover, we showed that $E_0(2)$, is the only Lie group with locally
symmetric left invariant Riemannian metrics which are not symmetric.


title: Efficient Finite Groups Arising in the Study of Relative Asphericity

abstract:
  We study a class of two-generator two-relator groups, denoted $J_n(m,k)$,
that arise in the study of relative asphericity as groups satisfying a
transitional curvature condition. Particular instances of these groups occur in
the literature as finite groups of intriguing orders. Here we find infinite
families of non-elementary virtually free groups and of finite metabelian
non-nilpotent groups, for which we determine the orders. All Mersenne primes
arise as factors of the orders of the non-metacyclic groups in the class, as do
all primes from other conjecturally infinite families of primes. We classify
the finite groups up to isomorphism and show that our class overlaps and
extends a class of groups $F^{a,b,c}$ with trivalent Cayley graphs that was
introduced by C.M.Campbell, H.S.M.Coxeter, and E.F.Robertson. The theory of
cyclically presented groups informs our methods and we extend part of this
theory (namely, on connections with polynomial resultants) to "bicyclically
presented groups" that arise naturally in our analysis. As a corollary to our
main results we obtain new infinite families of finite metacyclic generalized
Fibonacci groups.


title: A First Look at User Activity on Tinder

abstract:
  Mobile dating apps have become a popular means to meet potential partners.
Although several exist, one recent addition stands out amongst all others.
Tinder presents its users with pictures of people geographically nearby, whom
they can either like or dislike based on first impressions. If two users like
each other, they are allowed to initiate a conversation via the chat feature.
In this paper we use a set of curated profiles to explore the behaviour of men
and women in Tinder. We reveal differences between the way men and women
interact with the app, highlighting the strategies employed. Women attain large
numbers of matches rapidly, whilst men only slowly accumulate matches. To
expand on our findings, we collect survey data to understand user intentions on
Tinder. Most notably, our results indicate that a little effort in grooming
profiles, especially for male users, goes a long way in attracting attention.


title: Long-Lived Spiral Structure for Galaxies with Intermediate Size Bulges

abstract:
  Spiral structure in disk galaxies is modeled with nine collisionless N-body
simulations including live disks, halos, and bulges with a range of masses. Two
of these simulations make long-lasting and strong two-arm spiral wave modes
that last for $\sim5$ Gyr with constant pattern speed. These two had a light
stellar disk and the largest values of the Toomre $Q$ parameter in the inner
region at the time the spirals formed, suggesting the presence of a Q-barrier
to wave propagation resulting from the bulge. The relative bulge mass in these
cases is about 10\%. Models with weak two-arm spirals had pattern speeds that
followed the radial dependence of the Inner Lindblad Resonance.


title: MICADO: first light imager for the E-ELT

abstract:
  MICADO will equip the E-ELT with a first light capability for diffraction
limited imaging at near-infrared wavelengths. The instrument's observing modes
focus on various flavours of imaging, including astrometric, high contrast, and
time resolved. There is also a single object spectroscopic mode optimised for
wavelength coverage at moderately high resolution. This contribution provides
an overview of the key functionality of the instrument, outlining the
scientific rationale for its observing modes. The interface between MICADO and
the adaptive optics system MAORY that feeds it is summarised. The design of the
instrument is discussed, focussing on the optics and mechanisms inside the
cryostat, together with a brief overview of the other key sub-systems.


title: Too much regularity may force too much uniqueness

abstract:
  Time-dependent fractional-derivative problems $D_t^\delta u + Au = f$ are
considered, where $D_t^\delta$ is a Caputo fractional derivative of order
$\delta\in (0,1)\cup (1,2)$ and~$A$ is a classical elliptic operator, and
appropriate boundary and initial conditions are applied. The regularity of
solutions to this class of problems is discussed, and it is shown that assuming
more regularity than is generally true---as many researchers do---places a
surprisingly severe restriction on the problem.


title:
Systematic Comparison of Tsallis Statistics for Charged Pions Produced
  In $pp$ Collisions

abstract:
  The energy dependence of Tsallis statistics parameters is presented for
charged pions produced at beam energies ranging between 6.3 GeV and 7 TeV. It
is found that deviations from Boltzmann statistics are monotonically growing
with beam energy. This may be attributed to the dominance of low $x$ at higher
energies leading to the power-like NLO QCD spectra for which Tsallis statistics
may serve as effective theory. At the same time, for larger $x$ at lower beam
energies the Gaussian falloff of transverse-momentum-dependent distributions is
crucial and correspondent effective description is provided by the Boltzmann
distribution.


title: Balanced factorisations in some algebras

abstract:
  We prove that, in any field of characteristic not two and not three except
the five-element field, each element decomposes into a product of four factors
whose sum vanishes. We also find all $k,n,q$ such that every $n\times n$ matrix
over the $q$-element field decomposes into a product of $k$ commuting matrices
whose sum vanishes.


title: Stock trend prediction using news sentiment analysis

abstract:
  Efficient Market Hypothesis is the popular theory about stock prediction.
With its failure much research has been carried in the area of prediction of
stocks. This project is about taking non quantifiable data such as financial
news articles about a company and predicting its future stock trend with news
sentiment classification. Assuming that news articles have impact on stock
market, this is an attempt to study relationship between news and stock trend.
To show this, we created three different classification models which depict
polarity of news articles being positive or negative. Observations show that RF
and SVM perform well in all types of testing. Na\"ive Bayes gives good result
but not compared to the other two. Experiments are conducted to evaluate
various aspects of the proposed model and encouraging results are obtained in
all of the experiments. The accuracy of the prediction model is more than 80%
and in comparison with news random labeling with 50% of accuracy; the model has
increased the accuracy by 30%.


title:
The Energy Landscape of Neurophysiological Activity Implicit in Brain
  Network Structure

abstract:
  A critical mystery in neuroscience lies in determining how anatomical
structure impacts the complex functional dynamics of human thought. How does
large-scale brain circuitry constrain states of neuronal activity and
transitions between those states? We address these questions using a maximum
entropy model of brain dynamics informed by white matter tractography. We
demonstrate that the most probable brain states -- characterized by minimal
energy -- display common activation profiles across brain areas: local
spatially-contiguous sets of brain regions reminiscent of cognitive systems are
co-activated frequently. The predicted activation rate of these systems is
highly correlated with the observed activation rate measured in a separate
resting state fMRI data set, validating the utility of the maximum entropy
model in describing neurophysiologial dynamics. This approach also offers a
formal notion of the energy of activity within a system, and the energy of
activity shared between systems. We observe that within- and between-system
energies cleanly separate cognitive systems into distinct categories, optimized
for differential contributions to integrated v.s. segregated function. These
results support the notion that energetic and structural constraints
circumscribe brain dynamics, offering novel insights into the roles that
cognitive systems play in driving whole-brain activation patterns.


title:
Temperature dependence of the electrical resistivity and the anisotropic
  magnetoresistance (AMR) of electrodeposited Ni Co alloys

abstract:
  The electrical resistivity and the anisotropic magnetoresistance (AMR) was
investigated for Ni Co alloys at and below room temperature. The Ni Co alloy
layers having a thickness of about 2 um were prepared by electrodeposition on
Si wafers with evaporated Cr and Cu underlayers. The alloy composition was
varied in the whole concentration range by varying the ratio of Ni sulfate and
Co sulfate in the electrolyte. The Ni Co alloy deposits were investigated first
in the as deposited state on the substrates and then, by mechanically stripping
them from the substrates, as self supporting layers both without and after
annealing. According to an X ray diffraction study, a strongly textured face
centered cubic (fcc) structure was formed in the as deposited state with an
average grain size of about 10 nm. Upon annealing, the crystal structure was
retained whereas the grain size increased by a factor of 3 to 5, depending on
alloy composition. The zero field resistivity decreased strongly by annealing
due to the increased grain size. The annealing hardly changed the AMR below 50
at.% Co but strongly decreased it above this concentration. The composition
dependence of the resistivity and the AMR of the annealed Ni Co alloy deposits
was in good quantitative agreement with the available literature data both at
13 K and at room temperature. Both transport parameters were found to exhibit a
pronounced maximum in the composition range between 20 and 30 at.% Co and the
data of the Ni Co alloys fit well to the limiting values of the pure component
metals (fcc Ni and fcc Co). The only theoretical calculation reported formerly
on fcc Ni Co alloys yielded at T=0K a resistivity value smaller by a factor of
5 and an AMR value larger by a factor of about 2 than the corresponding low
temperature experimental data, although the theoretical results properly
reproduced the composition dependence of both quantities.


title: Mass decomposition of SLACS lens galaxies in Weyl conformal gravity

abstract:
  We study here, using the Mannheim-Kazanas solution of Weyl conformal theory,
the mass decomposition in the representative subsample of $57$ early-type
elliptical lens galaxies of the SLACS on board the HST. We begin by showing
that the solution need not be an exclusive solution of conformal gravity but
can also be viewed as a solution of a class of $f(R)$ gravity theories coupled
to non-linear electrodynamics thereby rendering the ensuing results more
universal. Since lensing involves light bending, we shall first show that the
solution adds to Schwarzschild light bending caused by the luminous mass
($M_{\ast }$) a positive contribution $+\gamma R$ contrary to the previous
results in the literature, thereby resolving a long standing problem. The cause
of the error is critically examined. Applying the expressions for light bending
together with an input equating Einstein and Weyl angles, we develop a novel
algorithm for separating the luminous component from the total lens mass
(luminous+dark) within the Einstein radius. Our results indicate that the
luminous mass estimates differ from the observed total lens masses by a linear
proportionality factor. In quantitative detail, we observe that the ratios of
luminous over total lens mass ($f^{\ast }$) within the Einstein radius of
individual galaxies take on values near unity, many of which remarkably fall
inside or just marginally outside the specified error bars obtained from a
simulation based on the Bruzual-Charlot stellar population synthesis model
together with the Salpeter IMF favored on the ground of metallicity
[Grillo,2009]. We shall also calculate the average dark matter density of
individual galaxies within their respective Einstein spheres. The present
approach, being truly analytic, seems to be the first of its kind attempting to
provide a new decomposition scheme distinct from the simulational ones.


title: The CMV bispectral problem

abstract:
  A classical result due to Bochner classifies the orthogonal polynomials on
the real line which are common eigenfunctions of a second order linear
differential operator. We settle a natural version of the Bochner problem on
the unit circle which answers a similar question concerning orthogonal Laurent
polynomials and can be formulated as a bispectral problem involving CMV
matrices. We solve this CMV bispectral problem in great generality proving
that, except the Lebesgue measure, no other one on the unit circle yields a
sequence of orthogonal Laurent polynomials which are eigenfunctions of a linear
differential operator of arbitrary order. Actually, we prove that this is the
case even if such an eigenfunction condition is imposed up to finitely many
orthogonal Laurent polynomials.


title: Sequence Training and Adaptation of Highway Deep Neural Networks

abstract:
  Highway deep neural network (HDNN) is a type of depth-gated feedforward
neural network, which has shown to be easier to train with more hidden layers
and also generalise better compared to conventional plain deep neural networks
(DNNs). Previously, we investigated a structured HDNN architecture for speech
recognition, in which the two gate functions were tied across all the hidden
layers, and we were able to train a much smaller model without sacrificing the
recognition accuracy. In this paper, we carry on the study of this architecture
with sequence-discriminative training criterion and speaker adaptation
techniques on the AMI meeting speech recognition corpus. We show that these two
techniques improve speech recognition accuracy on top of the model trained with
the cross entropy criterion. Furthermore, we demonstrate that the two gate
functions that are tied across all the hidden layers are able to control the
information flow over the whole network, and we can achieve considerable
improvements by only updating these gate functions in both sequence training
and adaptation experiments.


title: Evolution of an Accretion Disk in Binary Black Hole Systems

abstract:
  We investigate evolution of an accretion disc in binary black hole (BBH)
systems and possible electromagnetic counterparts of the gravitational waves
from mergers of BBHs. Perna et al. (2016) proposed a novel evolutionary
scenario of an accretion disc in BBHs in which a disc eventually becomes
"dead", i.e., the magnetorotational instability (MRI) becomes inactive. In
their scenario, the dead disc survives until {\it a few seconds before} the
merger event. We improve the dead disc model and propose another scenario,
taking account of effects of the tidal torque from the companion and the
critical ionization degree for MRI activation more carefully. We find that the
mass of the dead disc is much lower than that in the Perna's scenario. When the
binary separation sufficiently becomes small, the mass inflow induced by the
tidal torque reactivates MRI, restarting mass accretion onto the black hole. We
also find that this disc "revival" happens {\it more than thousands of years
before} the merger. The mass accretion induced by the tidal torque increases as
the separation decreases, and a relativistic jet could be launched before the
merger. The emissions from these jets are too faint compared to GRBs, but
detectable if the merger events happen within $\lesssim 10$ Mpc or if the
masses of the black holes are as massive as $\sim 10^5 M_{\odot}$.


title: Local Generalized Symmetries and Locally Symmetric Parabolic Geometries

abstract:
  We investigate (local) automorphisms of parabolic geometries that generalize
geodesic symmetries. We show that many types of parabolic geometries admit at
most one generalized geodesic symmetry at a point with non-zero harmonic
curvature. Moreover, we show that if there is exactly one symmetry at each
point, then the parabolic geometry is a generalization of an affine (locally)
symmetric space.


title: Dispersionless integrable hierarchies and GL(2,R) geometry

abstract:
  Paraconformal or $GL(2)$ geometry on an $n$-dimensional manifold $M$ is
defined by a field of rational normal curves of degree $n-1$ in the
projectivised cotangent bundle $\mathbb{P} T^*M$. Such geometry is known to
arise on solution spaces of ODEs with vanishing W\"unschmann
(Doubrov-Wilczynski) invariants. In this paper we discuss yet another natural
source of $GL(2)$ structures, namely dispersionless integrable hierarchies of
PDEs (for instance the dKP hierarchy). In the latter context, $GL(2)$
structures coincide with the characteristic variety (principal symbol) of the
hierarchy.
  Dispersionless hierarchies provide explicit examples of various particularly
interesting classes of $GL(2)$ structures studied in the literature. Thus, we
obtain torsion-free $GL(2)$ structures of Bryant that appeared in the context
of exotic holonomy in dimension four, as well as totally geodesic $GL(2)$
structures of Krynski. The latter, also known as involutive $GL(2)$ structures,
possess a compatible affine connection (with torsion) and a two-parameter
family of totally geodesic $\alpha$-manifolds (coming from the dispersionless
Lax equations), which makes them a natural generalisation of the Einstein-Weyl
geometry.
  Our main result states that involutive $GL(2)$ structures are governed by a
dispersionless integrable system. This establishes integrability of the system
of W\"unschmann conditions.


title: Rigorous Multiple-Precision Evaluation of D-Finite Functions in SageMath

abstract:
  We present a new open source implementation in the SageMath computer algebra
system of algorithms for the numerical solution of linear ODEs with polynomial
coefficients. Our code supports regular singular connection problems and
provides rigorous error bounds.


title:
Convergence of the MAC scheme for the compressible stationary
  Navier-Stokes equations

abstract:
  We prove in this paper the convergence of the Marker and Cell (MAC) scheme
for the discretization of the steady state compressible and isentropic
Navier-Stokes equations on two or three-dimensional Cartesian grids. Existence
of a solution to the scheme is proven, followed by estimates on approximate
solutions, which yield the convergence of the approximate solutions, up to a
subsequence, and in an appropriate sense. We then prove that the limit of the
approximate solutions satisfies the mass and momentum balance equations, as
well as the equation of state, which is the main difficulty of this study.


title:
A single-mode external cavity diode laser using an intra-cavity atomic
  Faraday filter with short-term linewidth $<400$ kHz and long-term stability
  of $<1$ MHz

abstract:
  We report on the development of a diode laser system - the `Faraday laser' -
using an atomic Faraday filter as the frequency-selective element. In contrast
to typical external-cavity diode laser systems which offer tunable output
frequency but require additional control systems in order to achieve a stable
output frequency, our system only lases at a single frequency, set by the peak
transmission frequency of the internal atomic Farady filter. Our system has
both short-term and long-term stability of less than 1~MHz, which is less than
the natural linewidth of alkali-atomic D-lines, making similar systems suitable
for use as a `turn-key' solution for laser cooling experiments.


title:
Compression and phase diagram of lithium hydrides at elevated pressures
  and temperatures by first-principles calculations

abstract:
  High pressure and high temperature properties of AB (A = $^6$Li, $^7$Li; B =
H, D, T) are investigated with first-principles method comprehensively. It is
found that the H$^{-}$ sublattice features in the low-pressure electronic
structure near the Fermi level of LiH are shifted to that dominated by the
Li$^{+}$ sublattice in compression. The lattice dynamics is studied in
quasi-harmonic approximation, from which the phonon contribution to the free
energy and the isotopic effects are accurately modelled with the aid of a
parameterized double-Debye model. The obtained equation of state (EOS) matches
perfectly with available static experimental data. The calculated principal
Hugoniot is also in accordance with that derived from shock wave experiments.
Using the calculated principal Hugoniot and the previous theoretical melting
curve, we predict a shock melting point at 56 GPa and 1923 K. In order to
establish the phase diagram for LiH, the phase boundaries between the B1 and B2
solid phases are explored. The B1-B2-liquid triple point is determined at about
241 GPa and 2413 K. The remarkable shift in the phase boundaries by isotopic
effect and temperature reveal the significant role played by lattice
vibrations. Furthermore, the Hugoniot of the static-dynamic coupling
compression is assessed. Our EOS suggests that a precompression of the sample
to 50 GPa will allow the shock Hugoniot passing through the triple point and
entering the B2 solid phase. This transition leads to a discontinuity with 4.6%
volume collapse, about four times greater than the same B1-B2 transition at
zero temperature.


title:
Superimposition of eye fundus images for longitudinal analysis from
  large public health databases

abstract:
  In this paper, a method is presented for superimposition (i.e. registration)
of eye fundus images from persons with diabetes screened over many years for
diabetic retinopathy. The method is fully automatic and robust to camera
changes and colour variations across the images both in space and time. All the
stages of the process are designed for longitudinal analysis of cohort public
health databases where retinal examinations are made at approximately yearly
intervals. The method relies on a model correcting two radial distortions and
an affine transformation between pairs of images which is robustly fitted on
salient points. Each stage involves linear estimators followed by non-linear
optimisation. The model of image warping is also invertible for fast
computation. The method has been validated (1) on a simulated montage and (2)
on public health databases with 69 patients with high quality images (271 pairs
acquired mostly with different types of camera and 268 pairs acquired mostly
with the same type of camera) with success rates of 92% and 98%, and five
patients (20 pairs) with low quality images with a success rate of 100%.
Compared to two state-of-the-art methods, ours gives better results.


title: Age velocity dispersion relations and heating histories in disc galaxies

abstract:
  We analyse the heating of stellar discs by non axisymmetric structures and
giant molecular clouds (GMCs) in N-body simulations of growing disc galaxies.
The analysis resolves long-standing discrepancies between models and data by
demonstrating the importance of distinguishing between measured age-velocity
dispersion relations (AVRs) and the heating histories of the stars that make up
the AVR. We fit both AVRs and heating histories with formulae proportional to
t^beta and determine the exponents beta_R and beta_z derived from in-plane and
vertical AVRs and ~beta_R and ~beta_z from heating histories. Values of beta_z
are in almost all simulations larger than values of ~beta_z, whereas values of
beta_R are similar to or mildly larger than values of ~beta_R. Moreover, values
of beta_z (~beta_z) are generally larger than values of beta_R (~beta_R). The
dominant cause of these relations is the decline over the life of the disc in
importance of GMCs as heating agents relative to spiral structure and the bar.
We examine how age errors and biases in solar neighbourhood surveys influence
the measured AVR: they tend to decrease beta values by smearing out ages and
thus measured dispersions. We compare AVRs and velocity ellipsoid shapes
sigma_z/sigma_R from simulations to Solar neighbourhood data. We conclude that
for the expected disc mass and dark halo structure, combined GMC and spiral/bar
heating can explain the AVR of the Galactic thin disc. Strong departures of the
disc mass or the dark halo structure from expectation spoil fits to the data.


title: On the relation between hyperrings and fuzzy rings

abstract:
  We construct a full embedding of the category of hyperfields into Dress's
category of fuzzy rings and explicitly characterize the essential image --- it
fails to be essentially surjective in a very minor way. This embedding provides
an identification of Baker's theory of matroids over hyperfields with Dress's
theory of matroids over fuzzy rings (provided one restricts to those fuzzy
rings in the essential image). The embedding functor extends from hyperfields
to hyperrings, and we study this extension in detail. We also analyze the
relation between hyperfields and Baker's partial demifields.


title: Does Eulerian percolation on $Z^2$ percolate ?

abstract:
  Eulerian percolation on Z 2 with parameter p is the classical Bernoulli bond
percolation with parameter p conditioned on the fact that every site has an
even degree. We first explain why Eulerian percolation with parameter p
coincides with the contours of the Ising model for a well-chosen parameter
$\beta$(p). Then we study the percolation properties of Eulerian percolation.


title: Kinetic theory of particle interactions mediated by dynamical networks

abstract:
  We provide a detailed multiscale analysis of a system of particles
interacting through a dynamical network of links. Starting from a microscopic
model, via the mean field limit, we formally derive coupled kinetic equations
for the particle and link densities, following the approach of [Degond et al.,
M3AS, 2016]. Assuming that the process of remodelling the network is very fast,
we simplify the description to a macroscopic model taking the form of single
aggregation-diffusion equation for the density of particles. We analyze
qualitatively this equation, addressing the stability of a homogeneous
distribution of particles for a general potential. For the Hookean potential we
obtain a precise condition for the phase transition, and, using the central
manifold reduction, we characterize the type of bifurcation at the instability
onset.


title:
Neutron monitors and muon detectors for solar modulation studies: 2.
  $\phi$ time series

abstract:
  The level of solar modulation at different times (related to the solar
activity) is a central question of solar and galactic cosmic-ray physics. In
the first paper of this series, we have established a correspondence between
the uncertainties on ground-based detectors count rates and the parameter
$\phi$ (modulation level in the force-field approximation) reconstructed from
these count rates. In this second paper, we detail a procedure to obtain a
reference $\phi$ time series from neutron monitor data. We show that we can
have an unbiased and accurate $\phi$ reconstruction ($\Delta\phi/\phi\simeq
10\%$). We also discuss the potential of Bonner spheres spectrometers and muon
detectors to provide $\phi$ time series. Two by-products of this calculation
are updated $\phi$ values for the cosmic-ray database and a web interface to
retrieve and plot $\phi$ from the 50's to today
(\url{http://lpsc.in2p3.fr/crdb}).


title:
Deep Depth Super-Resolution : Learning Depth Super-Resolution using Deep
  Convolutional Neural Network

abstract:
  Depth image super-resolution is an extremely challenging task due to the
information loss in sub-sampling. Deep convolutional neural network have been
widely applied to color image super-resolution. Quite surprisingly, this
success has not been matched to depth super-resolution. This is mainly due to
the inherent difference between color and depth images. In this paper, we
bridge up the gap and extend the success of deep convolutional neural network
to depth super-resolution. The proposed deep depth super-resolution method
learns the mapping from a low-resolution depth image to a high resolution one
in an end-to-end style. Furthermore, to better regularize the learned depth
map, we propose to exploit the depth field statistics and the local correlation
between depth image and color image. These priors are integrated in an energy
minimization formulation, where the deep neural network learns the unary term,
the depth field statistics works as global model constraint and the color-depth
correlation is utilized to enforce the local structure in depth images.
Extensive experiments on various depth super-resolution benchmark datasets show
that our method outperforms the state-of-the-art depth image super-resolution
methods with a margin.


title:
Multiple zeta functions of Kaneko-Tsumura type and their values at
  positive integers

abstract:
  Kaneko and Tsumura introduced a new kind of multiple zeta functions
$\eta(k_1,\ldots,k_r;s_1,\ldots,s_r)$. This is an analytic function of complex
variables $s_1,\ldots,s_r$, while $k_1,\ldots,k_r$ are non-positive integer
parameters. In this paper, we first extend this function to an analytic
function $\eta(s'_1,\ldots,s'_r;s_1,\ldots,s_r)$ of $2r$ complex variables.
Then we investigate its special values at positive integers. In particular, we
prove some linear relations among these $\eta$-values and the multiple zeta
values $\zeta(k_1,\ldots,k_r)$ of Euler-Zagier type.


title:
Untrimmed Video Classification for Activity Detection: submission to
  ActivityNet Challenge

abstract:
  Current state-of-the-art human activity recognition is focused on the
classification of temporally trimmed videos in which only one action occurs per
frame. We propose a simple, yet effective, method for the temporal detection of
activities in temporally untrimmed videos with the help of untrimmed
classification. Firstly, our model predicts the top k labels for each untrimmed
video by analysing global video-level features. Secondly, frame-level binary
classification is combined with dynamic programming to generate the temporally
trimmed activity proposals. Finally, each proposal is assigned a label based on
the global label, and scored with the score of the temporal activity proposal
and the global score. Ultimately, we show that untrimmed video classification
models can be used as stepping stone for temporal detection.


title:
Joint reconstruction strategy for structured illumination microscopy
  with unknown illuminations

abstract:
  The blind structured illumination microscopy (SIM) strategy proposed in
(Mudry et al., 1992) is fully re-founded in this paper, unveiling the central
role of the sparsity of the illumination patterns in the mechanism that drives
super-resolution in the method. A numerical analysis shows that the resolving
power of the method can be further enhanced with optimized one-photon or
two-photon speckle illuminations. A much improved numerical implementation is
provided for the reconstruction problem under the image positivity constraint.
This algorithm rests on a new preconditioned proximal iteration faster than
existing solutions, paving the way to 3D and real-time 2D reconstruction


title:
Nesterov's Accelerated Gradient and Momentum as approximations to
  Regularised Update Descent

abstract:
  We present a unifying framework for adapting the update direction in
gradient-based iterative optimization methods. As natural special cases we
re-derive classical momentum and Nesterov's accelerated gradient method,
lending a new intuitive interpretation to the latter algorithm. We show that a
new algorithm, which we term Regularised Gradient Descent, can converge more
quickly than either Nesterov's algorithm or the classical momentum algorithm.


title: Gamma factors root numbers and distinction

abstract:
  We study a relation between distinction and special values of local
invariants for representations of the general linear group over a quadratic
extension of $p$-adic fields. We show that the local Rankin-Selberg root number
of any pair of distinguished representation is trivial and as a corollary we
obtain an analogue for the global root number of any pair of distinguished
cuspidal representations. We further study the extent to which the gamma factor
at $1/2$ is trivial for distinguished representations as well as the converse
problem.


title:
Synchronization Detection in Networks of Coupled Oscillators for Pattern
  Recognition

abstract:
  Coupled oscillator-based networks are an attractive approach for implementing
hardware neural networks based on emerging nanotechnologies. However, the
readout of the state of a coupled oscillator network is a difficult challenge
in hardware implementations, as it necessitates complex signal processing to
evaluate the degree of synchronization between oscillators, possibly more
complicated than the coupled oscillator network itself. In this work, we focus
on a coupled oscillator network particularly adapted to emerging technologies,
and evaluate two schemes for reading synchronization patterns that can be
readily implemented with basic CMOS circuits. Through simulation of a simple
generic coupled oscillator network, we compare the operation of these readout
techniques with a previously proposed full statistics evaluation scheme. Our
approaches provide results nearly identical to the mathematical method, but
also show better resilience to moderate noise, which is a major concern for
hardware implementations. These results open the door to widespread realization
of hardware coupled oscillator-based neural systems.


title:
Many-body decoherence dynamics and optimised operation of a
  single-photon switch

abstract:
  We develop a theoretical framework to characterize the decoherence dynamics
due to multi-photon scattering in an all-optical switch based on Rydberg atom
induced nonlinearities. By incorporating the knowledge of this decoherence
process into optimal photon storage and retrieval strategies, we establish
optimised switching protocols for experimentally relevant conditions, and
evaluate the corresponding limits in the achievable fidelities. Based on these
results we work out a simplified description that reproduces recent experiments
[arXiv:1511.09445] and provides a new interpretation in terms of many-body
decoherence involving multiple incident photons and multiple gate excitations
forming the switch. Aside from offering insights into the operational capacity
of realistic photon switching capabilities, our work provides a complete
description of spin wave decoherence in a Rydberg quantum optics setting, and
has immediate relevance to a number of further applications employing photon
storage in Rydberg media.


title:
A Common Derivation for Markov Chain Monte Carlo Algorithms with
  Tractable and Intractable Targets

abstract:
  Markov chain Monte Carlo is a class of algorithms for drawing Markovian
samples from high-dimensional target densities to approximate the numerical
integration associated with computing statistical expectation, especially in
Bayesian statistics. However, many Markov chain Monte Carlo algorithms do not
seem to share the same theoretical support and each algorithm is proven in a
different way. This incurs many terminologies and ancillary concepts, which
makes Markov chain Monte Carlo literature seems to be scattered and
intimidating to researchers from many other fields, including new researchers
of Bayesian statistics.
  A generalised version of the Metropolis-Hastings algorithm is constructed
with a random number generator and a self-reverse mapping. This formulation
admits many other Markov chain Monte Carlo algorithms as special cases. A
common derivation for many Markov chain Monte Carlo algorithms is useful in
drawing connections and comparisons between these algorithms. As a result, we
now can construct many novel combinations of multiple Markov chain Monte Carlo
algorithms that amplify the efficiency of each individual algorithm.
Specifically, we propose two novel sampling schemes that combine slice sampling
with directional or Hamiltonian sampling. Our Hamiltonian slice sampling scheme
is also applicable in the pseudo-marginal context where the target density is
intractable but can be unbiasedly estimated, e.g. using particle filtering.


title:
On multiscale Gevrey and q-Gevrey asymptotics for some linear
  q-difference differential initial value Cauchy problems

abstract:
  We study the asymptotic behavior of the solutions related to a singularly
perturbed q-difference-differential problem in the complex domain. The analytic
solution can be splitted according to the nature of the equation and its
geometry so that both, Gevrey and q-Gevrey asymptotic phenomena are observed
and can be distinguished, relating the analytic and the formal solution.
  The proof leans on a two level novel version of Ramis-Sibuya theorem under
Gevrey and q-Gevrey orders.


title:
Numerical study of blow-up and stability of line solitons for the
  Novikov-Veselov equation

abstract:
  We study numerically the evolution of perturbed Korteweg-de Vries solitons
and of well localized initial data by the Novikov-Veselov (NV) equation at
different levels of the "energy" parameter $ E $. We show that as $ |E| \to
\infty $, NV behaves, as expected, similarly to its formal limit, the
Kadomtsev-Petviashvili equation. However at intermediate regimes, i.e. when $ |
E | $ is not very large, more varied scenarios are possible, in particular,
blow-ups are observed. The mechanism of the blow-up is studied.


title:
Note on the Coulomb blockade of a weak tunnel junction with Nyquist
  noise: Conductance formula for a broad temperature range

abstract:
  We revisit the Coulomb blockade of the tunnel junction with conductance much
smaller than $e^2/\hbar$. We study the junction with capacitance $C$, embedded
in an Ohmic electromagnetic environment modelled by a series resistance $R$
which produces the Nyquist noise. In the semiclassical limit the Nyquist noise
charges the junction by a random charge with a Gaussian distribution. Assuming
the Gaussian distribution, we derive analytically the temperature-dependent
junction conductance $G(T)$ valid for temperatures $k_BT \gtrsim (R_K/2\pi
R)E_c$ and resistances $R \gtrsim R_K$, where $R_K = h/e^2$ and $E_c=e^2/2C \
\text{is}$ the single-electron charging energy. Our analytical result shows the
leading dependence $G(T) \propto e^{-E_c/4k_BT}$, so far believed to exist only
if $(R_K/\pi R)E_c \ll k_BT \ll E_c$ and $R \gg R_K$. The validity of our
result for $k_BT \gtrsim (R_K/2\pi R)E_c$ and $R \gtrsim R_K$ is confirmed by a
good agreement with the numerical studies which do not assume the semiclassical
limit, and by a reasonable agreement with experimental data for $R$ as low as
$R_K$. Our result also reproduces various asymptotic formulae derived in the
past. The factor of $1/4$ in the activation energy $E_c/4$ is due to the
semiclassical Nyquist noise.


title: Demand-Flow of Agents with Gross-Substitute Valuations

abstract:
  We consider the class of valuations on indivisible items called
gross-substitute (GS). This class was introduced by Kelso and Crawford (1982)
and is widely used in studies of markets with indivisibilities. GS is a
condition on the demand-flow in a specific scenario: some items become more
expensive while other items retain their price. We prove that GS implies a much
stronger condition, describing the demand-flow in the general scenario in which
all prices may change. We prove that the demand of GS agents always flows
(weakly) downwards, i.e, from items with higher price-increase to items with
lower price-increase. We show that this property is equivalent to GS and is not
true when there are complementarities.


title:
A Maturity Model for Public Administration as Open Translation Data
  Providers

abstract:
  Any public administration that produces translation data can be a provider of
useful reusable data to meet its own translation needs and the ones of other
public organizations and private companies that work with texts of the same
domain. These data can also be crucial to produce domain-tuned Machine
Translation systems. The organization's management of the translation process,
the characteristics of the archives of the generated resources and of the
infrastructure available to support them determine the efficiency and the
effectiveness with which the materials produced can be converted into reusable
data. However, it is of utmost importance that the organizations themselves
first become aware of the goods they are producing and, second, adapt their
internal processes to become optimal providers. In this article, we propose a
Maturity Model to help these organizations to achieve it by identifying the
different stages of the management of translation data that determine the path
to the aforementioned goal.


title:
Distributed optimal control of a nonstandard nonlocal phase field system
  with double obstacle potential

abstract:
  This paper is concerned with a distributed optimal control problem for a
nonlocal phase field model of Cahn-Hilliard type, which is a nonlocal version
of a model for two-species phase segregation on an atomic lattice under the
presence of diffusion. The local model has been investigated in a series of
papers by P. Podio-Guidugli and the present authors; the nonlocal model studied
here consists of a highly nonlinear parabolic equation coupled to an ordinary
differential inclusion of subdifferential type. The inclusion originates from a
free energy containing the indicator function of the interval in which the
order parameter of the phase segregation attains its values. It also contains a
nonlocal term modeling long-range interactions. Due to the strong nonlinear
couplings between the state variables (which even involve products with time
derivatives), the analysis of the state system is difficult. In addition, the
presence of the differential inclusion is the reason that standard arguments of
optimal control theory cannot be applied to guarantee the existence of Lagrange
multipliers. In this paper, we employ recent results proved for smooth
logarithmic potentials and perform a so-called `deep quench' approximation to
establish existence and first-order necessary optimality conditions for the
nonsmooth case of the double obstacle potential.


title:
The 0.7 anomaly in quantum point contact; many-body or single-electron
  effect?

abstract:
  Apart from usual quantization steps on the ballistic conductance of a
quasi-one-dimensional conductor, an additional plateau-like feature appears at
a fraction of about 0.7 below the first conductance step in GaAs-based quantum
point contacts (QPCs). Despite a tremendous amount of research on this
anomalous feature, its origin remains still unclear. Here, a unique model of
this anomaly is proposed relied on fundamental principles of quantum mechanics.
It is noticed that just after opening a quasi-1D conducting channel in the QPC
a single electron travels the channel at a time, and such electron can be - in
principle - observed. The act of observation destroys superposition of spin
states, in which the electron otherwise exists, and this suppresses their
quantum interference. It is shown that the QPC-conductance is then reduded by a
factor of 0.74. "Visibility" of electron is enhanced if the electron spends
some time in the channel due to resonant transmission. Electron's resonance can
also explain an unusual temperature behaviour of the anomaly, as well as its
recently discovered feature: oscillatory modulation as a function of the
channel length and electrostatic potential. A recipe for experimental
verification of the model is given.


title: Biabduction (and Related Problems) in Array Separation Logic

abstract:
  We investigate array separation logic (ASL), a variant of symbolic-heap
separation logic in which the data structures are either pointers or arrays,
i.e., contiguous blocks of allocated memory. This logic provides a language for
compositional memory safety proofs of imperative array programs.
  We focus on the biabduction problem for this logic, which has been
established as the key to automatic specification inference at the industrial
scale. We present an NP decision procedure for biabduction in ASL that produces
solutions of reasonable quality, and we also show that the problem of finding a
consistent solution is NP-hard.
  Along the way, we study satisfiability and entailment in our logic, giving
decision procedures and complexity bounds for both problems. We show
satisfiability to be NP-complete, and entailment to be decidable with high
complexity. The somewhat surprising fact that biabduction is much simpler than
entailment is explained by the fact that, as we show, the element of choice
over biabduction solutions enables us to dramatically reduce the search space.


title:
Sobolev spaces on non-Lipschitz subsets of $\mathbb{R}^n$ with
  application to boundary integral equations on fractal screens

abstract:
  We study properties of the classical fractional Sobolev spaces (or Bessel
potential spaces) on non-Lipschitz subsets of $\mathbb{R}^n$. We investigate
the extent to which the properties of these spaces, and the relations between
them, that hold in the well-studied case of a Lipschitz open set, generalise to
non-Lipschitz cases. Our motivation is to develop the functional analytic
framework in which to formulate and analyse integral equations on non-Lipschitz
sets. In particular we consider an application to boundary integral equations
for wave scattering by planar screens that are non-Lipschitz, including cases
where the screen is fractal or has fractal boundary.


title:
Improper signaling and symbol extensions: How far can we go with
  Gaussian P2P codebooks in the interfering MAC with TIN?

abstract:
  Meeting the challenges of 5G demands better exploitation of the available
spectrum by allowing multiple parties to share resources. For instance, a
secondary unlicensed system can share resources with the cellular uplink of a
primary licensed system for an improved spectral efficiency. This induces
interference which has to be taken into account when designing such a system. A
simple yet robust strategy is treating interference as noise (TIN), which is
widely adapted in practice. It is thus important to study the capabilities and
limitations of TIN in such scenarios. In this paper, we study this scenario
modelled as Multiple Access Channel (MAC) interfered by a Point-to-Point (P2P)
channel. Here, we focus on rate maximization and power minimization problems
separately. We use improper Gaussian signaling (instead of proper) at the
transmitters to increase the design flexibility, which offers the freedom of
optimizing the transmit signal pseudo-variance in addition to its variance.
Furthermore, we allow correlation among the transmitted signals over orthogonal
resource basis (i.e., time or frequency) for the purpose of optimal signaling
design over the extended channel. We formulate the rate maximization problem as
a semidefinite program, and use semidefinite relaxation (SDR) to obtain a
near-optimal solution. Numerical optimizations show that, by improper Gaussian
signaling the achievable rates can be improved upto three times depending on
the strength of the interfering links. Furthermore, we observe significant
benefits in power consumption by improper Gaussian signaling with symbol
extensions compared to the traditional proper Gaussian signaling.
Interestingly, by minimizing sum power given the solution of the rate
maximization problem improves the energy efficiency significantly.


title:
Optimizing Access Mechanisms for QoS Provisioning in Hardware
  Constrained Dynamic Spectrum Access

abstract:
  One of the major challenges in Dynamic Spectrum Access (DSA) systems is to
guarantee a required level of Quality of Service (QoS) to secondary users of
the spectrum. In this paper, we propose efficient algorithms for deriving
optimal policies for the sensing / transmitting trade-off in
hardware-constrained DSA systems. Unlike previous approaches which seek to
maximize mean data rate for the secondary users, the proposed algorithms derive
policies which minimize the probability of excessive queuing delays. Large
Deviations (LD) asymptotics are used to approximate the probability of interest
and policies maximizing the associated LD exponent are proposed. Although
dynamic programming is not able to identify the optimal policy in this case,
much more efficient algorithms than exhaustive search are proposed. These
algorithms are based on specific properties of the optimal policy which are
described and proven in this paper.


title:
On the semi-convergence of regularized HSS iteration methods for
  singular saddle point problems from the Stokes equations

abstract:
  Recently, Bai and Benzi proposed a class of regularized Hermitian and
skew-Hermitian splitting methods (RHSS) iteration methods for solving the
nonsingular saddle point problem. In this paper, we apply this method to solve
the singular saddle point problem from the Stokes equations. In the process of
the semi-convergence analysis, we get that the RHSS method and the HSS method
are unconditionally semi-convergent, which weaken the previous results. Then
some spectral properties of the corresponding preconditioned matrix and a class
of improved preconditioned matrix are analyzed. Finally, some numerical
experiments on linear systems arising from the discretization of the Stokes
equations are presented to illustrate the feasibility and effectiveness of this
method and preconditioners.


title: On the Ages of Resonant, Eroded and Fossil Asteroid Families

abstract:
  In this work we have estimated 10 collisional ages of 9 families for which
for different reasons our previous attempts failed. In general, these are
difficult cases that required dedicated effort, such as a new family
classifications for asteroids in mean motion resonances, as well as a revision
of the classification inside the $3/2$ resonance. Of the families locked in
mean motion resonances, we succeeded in determining ages of the families of
(1911) Schubart and of the "super-Hilda" family, assuming this is actually a
severely eroded original family of (153) Hilda. In the Trojan region we found
families with almost no Yarkovsky evolution, for which we could compute only
physically implausible ages. Hence, we interpreted their modest dispersions of
proper eccentricities and inclinations as implying that the Trojan asteroid
families are fossil families, frozen at their proper elements determined by the
original ejection velocity field. We have found a new family, among the Griquas
locked in the 2/1 resonance with Jupiter: (11097) 1994 UD1. We have estimated
the ages of 6 families affected by secular resonances: families of (5) Astraea,
(25) Phocaea, (283) Emma, (363) Padua, (686) Gersuind, and (945) Barcelona. By
using a numerical calibration method, we have shown that the secular resonances
do not affect significanly the secular change of proper a. For the family of
(145) Adeona we could estimate the age only after removal of a number of
assumed interlopers. With the present paper we have concluded the series
dedicated to the determination of asteroid ages with a uniform method. We
computed the ages for a total of 57 families with $>100$ members. There remain
families too small at present to provide reliable estimates, as well as some
complex families (221, 135, 298) which may have more ages than we could
currently estimate.


title:
Inferring the contiguity matrix for spatial autoregressive analysis with
  applications to house price prediction

abstract:
  Inference methods in traditional statistics, machine learning and data mining
assume that data is generated from an independent and identically distributed
(iid) process. Spatial data exhibits behavior for which the iid assumption must
be relaxed. For example, the standard approach in spatial regression is to
assume the existence of a contiguity matrix which captures the spatial
autoregressive properties of the data. However all spatial methods, till now,
have assumed that the contiguity matrix is given apriori or can be estimated by
using a spatial similarity function. In this paper we propose a convex
optimization formulation to solve the spatial autoregressive regression (SAR)
model in which both the contiguity matrix and the non-spatial regression
parameters are unknown and inferred from the data. We solve the problem using
the alternating direction method of multipliers (ADMM) which provides a
solution which is both robust and efficient. While our approach is general we
use data from housing markets of Boston and Sydney to both guide the analysis
and validate our results. A novel side effect of our approach is the automatic
discovery of spatial clusters which translate to submarkets in the housing data
sets.


title: On Centres of 3-blocks of the Ree groups $^2G_2(q)$

abstract:
  Let $G:={^2G_2}(q)$ be the simple Ree group with $q=3^{2k+1}$ and $k$ a
positive integer. We show that the centre of the principal block $Z(kGe_0)$,
where $k$ is an algebraically closed field of characteristic $3$, is not
isomorphic to the centre of the Brauer corresponding block $Z(kN_G(P))$, where
$N_G(P)$ is the normaliser in $G$ of a Sylow $3$-subgroup. As part of the
proof, we compute the conjugacy classes of elements and the character tables of
the maximal parabolic subgroups of $G$.