title:
Infinitary Intersection Types as Sequences: a New Answer to Klop's
  Question

abstract:
  We provide a type-theoretical characterization of weakly-normalizing terms in
an infinitary lambda-calculus. We adapt for this purpose the standard
quantitative (with non-idempotent intersections) type assignment system of the
lambda-calculus to our infinite calculus. Our work provides a new answer to
Klop's HHN-problem, namely, finding out if there is a type system
characterizing the hereditary head-normalizing (HHN) lambda-terms. Tatsuta
showed that HHN could not be characterized by a finite type system. We prove
that an infinitary type system endowed with a validity condition called
approximability can achieve it.


title: The convergence problem in mean field games with a local coupling

abstract:
  The paper studies the convergence, as $N$ tends to infinity, of a system of
$N$ coupled Hamilton-Jacobi equations (the Nash system) when the coupling
between the players becomes increasingly singular. The limit equation is a mean
field game system with local coupling.


title: Recomposing rational functions

abstract:
  Let $A$ be a rational function. For any decomposition of $A$ into a
composition of rational functions $A=U\circ V$ the rational function
$\widetilde A=V\circ U$ is called an elementary transformation of $A$, and
rational functions $A$ and $B$ are called equivalent if there exists a chain of
elementary transformations between $A$ and $B$. This equivalence relation
naturally appears in the complex dynamics as a part of the problem of
describing of semiconjugate rational functions. In this paper we show that for
a rational function $A$ its equivalence class $[A]$ contains infinitely many
conjugacy classes if and only if $A$ is a flexible Latt\`es map. For flexible
Latt\`es maps $L=L_j$ induced by the multiplication by 2 on elliptic curves
with given $j$-invariant we provide a very precise description of $[ L]$.
Namely, we show that any rational function equivalent to $ L_j$ necessarily has
the form $ L_{j'}$ for some $j'\in \mathbb C$, and that the set of $j'\in
\mathbb C$ such that $ L_{j'}\sim L_{j}$ coincides with the orbit of $j$ under
the correspondence associated with the classical modular equation
$\Phi_2(x,y)=0$.


title:
NuSTAR observations of the Dwarf Nova GK Persei in 2015: comparison
  between outburst and quiescent phases

abstract:
  We report on NuSTAR observations of the Intermediate Polar GK Persei which
also behaves as a Dwarf Nova. It exhibited a Dwarf Nova outburst in 2015
March-April. The object was observed in 3-79 keV X-rays with NuSTAR, once at
the outburst peak, and again in 2015 September during quiescence. The 5-50 keV
flux during the outburst was 26 times higher than that during the quiescence.
With a multi-temperature emission model and a reflection model, we derived the
post-shock temperature as 19.2 +/- 0.7 keV in the outburst, and 38.5 +4.1/-3.6
keV in the quiescence. This temperature difference is considered to reflect
changes in the radius at which the accreting matter, forming an accretion disk,
is captured by the magnetosphere of the white dwarf (WD). Assuming that this
radius scales as the power of -2/7 of the mass accretion rate, and utilizing
the two temperature measurements, as well as the standard mass-radius relation
of WDs, we determined the WD mass in GK Persei as 0.90 +/- 0.06 solar masses.
The magnetic field is estimated as 4*10^5 G.


title:
Monitoring near-surface depth profile of residual stress in weakly
  anisotropic media by Rayleigh-wave dispersion

abstract:
  Herein we study the inverse problem on inferring depth profile of
near-surface residual stress in a weakly anisotropic medium by boundary
measurement of Rayleigh-wave dispersion if all other relevant material
parameters of the elastic medium are known. Our solution of this inverse
problem is based on a recently developed algorithm by which each term of a
high-frequency asymptotic formula for dispersion relations can be computed for
Rayleigh waves that propagate in various directions along the free surface of a
vertically-inhomogeneous, prestressed, and weakly anisotropic half-space. As a
prime example of possible applications we focus on a thick-plate sample of AA
7075-T651 aluminum alloy, which has one face treated by low plasticity
burnishing (LPB) that induced a depth-dependent prestress at and immediately
beneath the treated surface. We model the sample as a prestressed,
weakly-textured orthorhombic aggregate of cubic crystallites and assume that by
nondestructive and/or destructive measurements we have ascertained everything
about the sample, including the LPB-induced prestress, before it is put into
service. Under the supposition that the prestress be partially relaxed but
other material parameters remain unchanged after the sample undergoes a period
of service, we examine the possibility of inferring the depth profile of the
partially relaxed stress by boundary measurement of Rayleigh-wave dispersion.


title:
Towards a new generalized space expansion dynamics applied to the
  rotation of galaxies and Tully Fisher law

abstract:
  Up to now, the rotational velocities of galaxies are not clearly understood
and the experimental Tully Fisher rule, linking the total galactic mass to the
fourth power of the velocity, through an acceleration coefficient of about
10-10 m/s2 has not found a deep theoretical explanation. Tentative proposals
(MOND theory of a modified Newton s law and extraneous dark matter) do not
bring a definite clarification. We propose here a new approach to this problem,
without exotic matter and using the classical Newton force. But we introduce a
new additional universal acceleration, which could represent a universal
expansion law valid at the scale level of a galaxy. We show that this
hypothesis leads to a good description of the observed variations of the
galactic transverse velocity. It can be considered as a consequence of the
Scale Expansion Cosmos theory (SEC) introduced by J. Masreliez, but we
postulate that the space expansion acceleration universally applies at any
scale. We obtain a formal derivation of the Tully Fisher law, linking the
constant galactic transverse velocity to its total mass, via the universal
minimum acceleration. We derive a good estimate of the TF acceleration
coefficient and show that expansion should be proportional to the square root
of the local volumic mass density. Our conjecture is in fact a new dynamics
principle which could be applied to many other physical problems at different
scales. Applying it to the range of the solar planet system confirms the well
known Kepler laws, at least as a valid approximation for the order of magnitude
of the solar system.


title: High Energy Effects of Noncommutative Spacetime Geometry

abstract:
  In this paper, we endeavour to obtain a modified form of the Foldy-Wouthuysen
and Cini-Toushek transformations by resorting to the noncommutative nature of
space-time geometry, starting from the Klein-Gordon equation. Also, we obtain a
shift in the energy levels due to noncommutativity and from these results a
limit for the Lorentz factor in the ultra-relativistic case has been derived in
conformity with observations


title: Primordial Universe with radiation and Bose-Einstein condensate

abstract:
  In this work we derive a scenario {in which} the early universe consists of
{radiation fluid} and Bose-Einstein condensate. The possibility of
gravitational self-interaction due to an attractive Bose-Einstein condensate is
analyzed. The classical behavior of the scale factor of the universe is
determined by a parameter associated with the Bose-Einstein fluid with bouncing
or Big Crunch solutions. After we proceed to compute the finite-norm wave
packet solutions to the Wheeler-DeWitt equation. The behavior of the scale
factor is studied by applying the many-worlds interpretation of quantum
mechanics. The quantum cosmological model is free from the singularities.


title:
The Effect of Intra-Layer Bonding on Electron-Optical Phase Images of
  Few-Layer WSe2

abstract:
  The quantitative analysis of electron-optical phase images recorded using
off-axis electron holography often relies on the use of computer simulations of
electron propagation through a sample. However, simulations that make use of
the independent atom approximation are known to overestimate experimental phase
shifts by approximately 10%, as they neglect bonding effects. Here, we compare
experimental and simulated phase images for few-layer WSe2 . We show that a
combination of pseudopotentials and all-electron density functional theory
calculations can be used to obtain accurate mean electron phases, as well as
improved atomic-resolution spatial distribution of the electron phase. The
comparison demonstrates a perfect contrast match between experimental and
simulated atomic-resolution phase images for a sample of precisely know
thickness. The low computational cost of this approach makes it suitable for
the analysis of large electronic systems, including defects, substitutional
atoms and material interfaces.


title: Dirac and Maxwell equations in Split Octonions

abstract:
  The split octonionic form of Dirac and Maxwell equations are found. In
contrast with the previous attempts these equations are derived from the
octonionic analyticity condition and also we use different basis of the
8-dimensional space of split octonions.


title:
Nordhaus-Gaddum type inequalities for multiple domination and packing
  parameters in graphs

abstract:
  We study the Nordhaus-Gaddum type results for $(k-1,k,j)$ and $k$-domination
numbers of a graph $G$ and investigate these bounds for the $k$-limited packing
and $k$-total limited packing numbers in graphs. As the special case
$(k-1,k,j)=(1,2,0)$ we give an upper bound on $dd(G)+dd(\overline{G})$ stronger
than that presented by Harary and Haynes (1996). Moreover, we establish upper
bounds on the sum and product of packing and open packing numbers and
characterize all graphs attaining these bounds.


title:
Imaging the potential distribution of individual charged impurities on
  graphene by low-energy electron holography

abstract:
  While imaging individual atoms can routinely be achieved in high resolution
transmission electron microscopy, visualizing the potential distribution of
individually charged adsorbates leading to a phase shift of the probing
electron wave is still a challenging task. Low-energy electrons (30 - 250 eV)
are sensitive to localized potential gradients. We employed low-energy electron
holography to acquire in-line holograms of individual charged impurities on
free-standing graphene. By applying an iterative phase retrieval reconstruction
routine we recover the potential distribution of the localized charged
impurities present on free-standing graphene.


title: Mixed Neural Network Approach for Temporal Sleep Stage Classification

abstract:
  This paper proposes a practical approach to addressing limitations posed by
use of single active electrodes in applications for sleep stage classification.
Electroencephalography (EEG)-based characterizations of sleep stage progression
contribute the diagnosis and monitoring of the many pathologies of sleep.
Several prior reports have explored ways of automating the analysis of sleep
EEG and of reducing the complexity of the data needed for reliable
discrimination of sleep stages in order to make it possible to perform sleep
studies at lower cost in the home (rather than only in specialized clinical
facilities). However, these reports have involved recordings from electrodes
placed on the cranial vertex or occiput, which can be uncomfortable or
difficult for subjects to position. Those that have utilized single EEG
channels which contain less sleep information, have showed poor classification
performance. We have taken advantage of Rectifier Neural Network for feature
detection and Long Short-Term Memory (LSTM) network for sequential data
learning to optimize classification performance with single electrode
recordings. After exploring alternative electrode placements, we found a
comfortable configuration of a single-channel EEG on the forehead and have
shown that it can be integrated with additional electrodes for simultaneous
recording of the electroocuolgram (EOG). Evaluation of data from 62 people
(with 494 hours sleep) demonstrated better performance of our analytical
algorithm for automated sleep classification than existing approaches using
vertex or occipital electrode placements. Use of this recording configuration
with neural network deconvolution promises to make clinically indicated home
sleep studies practical.


title:
Back to the Origins. Using Matrix Functions of H\"uckel Hamiltonian for
  Quantum Interference

abstract:
  A book chapter where a new matrix function of the HMO Hamiltonian is proposed
to deal with the Quantum Interference phenomenon in conjugated organic
molecules.


title: Exhaustion of an interval by iterated Renyi parking

abstract:
  We study a variant of the R\'enyi parking problem in which car length is
repeatedly halved and determine the rate at which the remaining space decays.


title: The contrivance of Neptune

abstract:
  Celebrating 170th anniversary of the discovery of Neptune, I review the story
of the discovery that startled the world. The story is an interplay of
scientific triumph and human weakness and an example of how science works in a
socio-political context.


title: A classification of polyhedral graph by combinatorially rigid vertices

abstract:
  When the number of non-triangular faces adjacent to a vertex $v$ is less than
or equal to three, the vertex $v$ will be called (\emph{combinatorially})
\emph{rigid}.
  We study the number of rigid vertices and suggest a conjecture on a
classification of polyhedra.


title:
A Quantum Cellular Automata architecture with nearest neighbor
  interactions using one quantum gate type

abstract:
  We propose an architecture based on Quantum cellular Automata which allows
the use of only one type of quantum gates per computational step in order to
perform nearest neighbor interactions. The model is built in partial steps,
each one of them analyzed using nearest neighbor interactions, starting with
single qubit operations and continuing with two qubit ones. The effectiveness
of the model is tested and valuated by developing a quantum circuit
implementing the Quantum Fourier Transform. The important outcome of this
validation was that the operations are performed in a local and controlled
manner thus reducing the error rate of each computational step.


title: On weighted optimality of experimental designs

abstract:
  When the experimental objective is expressed by a set of estimable functions,
and any eigenvalue-based optimality criterion is selected, we prove the
equivalence of the recently introduced weighted optimality and the 'standard'
optimality criteria for estimating this set of functions of interest. Also,
given a weighted eigenvalue-based criterion, we construct a system of estimable
functions, so that the optimality for estimating this system of functions is
equivalent to the weighted optimality. This allows one to use the large body of
existing theoretical and computational results for the standard optimality
criteria for estimating a system of interest to derive theorems and numerical
algorithms for the weighted optimality of experimental designs. Moreover, we
extend the theory of weighted optimality so that it captures the experimental
objective consisting of any system of estimable functions, which was not the
case in the literature on weighted optimality so far. For any set of estimable
functions, we propose a corresponding weight matrix of a simple form, and with
a straightforward interpretation. Given a set of estimable functions with their
corresponding weights, we show that it is useful to distinguish between the
primary weights selected by the experimenters and the secondary weights implied
by the weight matrix.


title: The rotation of brown dwarfs

abstract:
  One of the characteristic features of low-mass stars is their propensity to
shed large amounts of angular momentum throughout their evolution. This
distinguishs them from brown dwarfs which remain fast rotators over timescales
of gigayears. Brown dwarfs with rotation periods longer than a couple of days
have only been found in star forming regions and young clusters. This is a
useful constraint on the mass dependency of mechanisms for angular momentum
regular in stars. Rotational braking by disks and winds become highly
inefficient in the substellar regime. In this short review I discuss the
observational evidence for the fast rotation in brown dwarfs, the implications,
and the link to the spin-mass relation in planets.


title:
Asymptotic Schur orthogonality in hyperbolic groups with application to
  monotony

abstract:
  We prove a generalization of Schur orthogonality relations for certain
classes of representations of Gromov hyperbolic groups. We apply the obtained
results to show that representations of non-abelian free groups associated to
the Patterson-Sullivan measures corresponding to a wide class of invariant
metrics on the group are monotonous in the sense introduced by Kuhn and Steger.
This in particular includes representations associated to harmonic measures of
a wide class of random walks.


title:
Coupling in the Heisenberg group and its applications to gradient
  estimates

abstract:
  We construct a non-Markovian coupling for hypoelliptic diffusions which are
Brownian motions in the three-dimensional Heisenberg group. We then derive
properties of this coupling such as estimates on the coupling rate, and upper
and lower bounds on the total variation distance between the laws of the
Brownian motions. Finally we use these properties to prove gradient estimates
for harmonic functions for the hypoelliptic Laplacian which is the generator of
Brownian motion in the Heisenberg group.


title:
Detecting and Summarizing Emergent Events in Microblogs and Social Media
  Streams by Dynamic Centralities

abstract:
  Methods for detecting and summarizing emergent keywords have been extensively
studied since social media and microblogging activities have started to play an
important role in data analysis and decision making. We present a system for
monitoring emergent keywords and summarizing a document stream based on the
dynamic semantic graphs of streaming documents. We introduce the notion of
dynamic eigenvector centrality for ranking emergent keywords, and present an
algorithm for summarizing emergent events that is based on the minimum weight
set cover. We demonstrate our system with an analysis of streaming Twitter data
related to public security events.


title:
Some Nonexistence Results for Strong External Difference Families Using
  Character Theory

abstract:
  In this paper, we study the existence of $(v,m,k,\lambda)$-strong external
difference families (SEDFs). We use character-theoretic techniques to show that
no SEDF exists when $v$ is prime, $k > 1$ and $m > 2$. In the case where $v$ is
the product of two distinct odd primes, some necessary conditions are derived,
which can be used to rule out certain parameter sets. Further, we show that,
when $m=3$ or $4$ and $v > m$, a $(v,m,k,\lambda)$-SEDF does not exist.


title:
Influence of the vector interaction and an external magnetic field on
  the isentropes near the chiral critical end point

abstract:
  The location of the critical end point (CEP) and the isentropic trajectories
in the QCD phase diagram are investigated. We use the (2+1)
Nambu$-$Jona-Lasinio model with the Polyakov loop coupling for different
scenarios, namely by imposing zero strange quark density, which is the case in
the ultra relativistic heavy-ion collisions, and $\beta$-equilibrium. The
influence of strong magnetic fields and of the vector interaction on the
isentropic trajectories around the CEP is discussed. It is shown that the
vector interaction and the magnetic field, having opposite effects on the
first-order transition, affect the isentropic trajectories differently: as the
vector interaction increases, the first-order transition becomes weaker and the
isentropes become smoother; when a strong magnetic field is considered, the
first-order transition is strengthened and the isentropes are pushed to higher
temperatures. No focusing of isentropes in region towards the CEP is seen.


title: Kernel Alignment for Unsupervised Transfer Learning

abstract:
  The ability of a human being to extrapolate previously gained knowledge to
other domains inspired a new family of methods in machine learning called
transfer learning. Transfer learning is often based on the assumption that
objects in both target and source domains share some common feature and/or data
space. In this paper, we propose a simple and intuitive approach that minimizes
iteratively the distance between source and target task distributions by
optimizing the kernel target alignment (KTA). We show that this procedure is
suitable for transfer learning by relating it to Hilbert-Schmidt Independence
Criterion (HSIC) and Quadratic Mutual Information (QMI) maximization. We run
our method on benchmark computer vision data sets and show that it can
outperform some state-of-art methods.


title:
Two-solar-mass hybrid stars: a two model description with the
  Nambu-Jona-Lasinio quark model

abstract:
  Hybrid stars with a quark phase described by the Nambu$-$Jona-Lasinio model
are studied. The hadron-quark model used to determine the stellar matter
equation of state favors the appearance of quark matter: the coincidence of the
deconfinement and chiral transitions and a low vacuum constituent quark mass.
These two properties are essential to build equations of state that predict
pure quark matter in the center of neutron stars. The effect of
vector-isoscalar and vector-isovector terms is discussed, and it is shown that
the vector-isoscalar terms are necessary to describe 2$M_\odot$ hybrid stars,
and the vector-isovector terms result in larger quark cores and a smaller
deconfinement density.


title:
Landau-Khalatnikov-Fradkin transformation for the fermion propagator in
  QED in arbitrary dimensions

abstract:
  We explore the dependence of fermion propagators on the covariant gauge
fixing parameter in quantum electrodynamics (QED) with the number of spacetime
dimensions kept explicit. Gauge covariance is controlled by the the
Landau-Khalatnikov-Fradkin transformation (LKFT). Utilizing its group nature,
the LKFT for a fermion propagator in Minkowski space is solved exactly. The
special scenario of 3D is used to test claims made for general cases. When
renormalized correctly, a simplification of the LKFT in 4D has been achieved
with the help of fractional calculus.


title:
Conical-Shaped Titania Nanotubes for Optimized Light Management in DSSCs
  Reach Back-side Illumination Efficiencies > 8%

abstract:
  In the present work, we introduce the anodic growth of conical shaped TiO2
nanotube arrays. These titania nanocones provide a scaffold for dye-sensitized
solar cell (DSSC) structures with significantly improved photon management,
providing an optimized absorption profile compared with conventional
cylindrical nanotube arrays. Finite difference time domain (FDTD) modelling
demonstrates a drastically changed power-absorption characteristic over the
tube length. When used in a back-side illumination DSSC configuration, nanocone
structures can reach over 60 % higher solar cell conversion efficiency than
conventional tubes. The resulting {\eta} of ca. 8 % represents one of the
highest reported values for Graetzel type DSSCs used under back-side
illumination.


title: A quarksonic matter at high isospin density

abstract:
  Analogous to the quarkyonic matter at high baryon density in which the quark
Fermi seas and the baryonic excitations coexist, it is argued that a
"quarksonic matter" phase appears at high isospin density where the quark
(antiquark) Fermi seas and the mesonic excitations coexist. We explore this
phase in detail in both large $N_c$ and asymptotically free limits: In large
$N_c$ limit, we sketch a phase diagram for the quarksonic matter. In the
asymptotically free limit, we study the pion superfluidity and thermodynamics
of the quarksonic matter by using both perturbative calculations and effective
model.


title: Operators with analytic orbit for the torus action

abstract:
  Let $T^n$ denote the n-dimensional torus. The class of the bounded operators
on $L^2(T^n)$ with analytic orbit under the action of $T^n$ by conjugation with
the translation operators is shown to coincide with the class of the zero-order
pseudodifferential operators on $T^n$ whose discrete symbol $(a_j)_{j\in Z^n}$
is uniformly analytic, in the sense that there exists $C>1$ such that the
derivatives of $a_j$ satisfy $|\partial^\alpha a_j(x)|\leq
C^{1+|\alpha|}\alpha!$ for all $x\in T^n$, all $j\in Z^n$ and all $\alpha\in
N^n$. This implies that this class of pseudodifferential operators is a
spectrally invariant *-subalgebra of the algebra of all bounded operators on
$L^2(T^n)$.


title: The Catalan Equation in Finitely Generated Domains

abstract:
  We consider the Catalan equation $x^p - y^q = 1$ in unknowns $x, y, p, q$,
where $x, y$ are taken from an integral domain $A$ of characteristic $0$ that
is finitely generated as a $\mathbb{Z}$-algebra and $p, q > 1$ are integers. We
give explicit upper bounds for $p$ and $q$ in terms of the defining parameters
of $A$. Our main theorem is a more precise version of a result of Brindza.
Brindza also gave inexplicit bounds for $p$ and $q$ in the special case that
$A$ is the ring of $S$-integers for some number field $K$. As part of the proof
of our main theorem, we will give a less technical proof for this special case
with explicit upper bounds for $p$ and $q$.


title: Self-dual representations of Sp(4,F)

abstract:
  Let $F$ be a non-Archimedean local field of characteristic $0$ and
$G=Sp(4,F)$. Let $(\pi,W)$ be an irreducible smooth self-dual representation
$G$. The space $W$ of $\pi$ admits a non-degenerate $G$-invariant bilinear form
$(\,,\,)$ which is unique up to scaling. The form $(\,,\,)$ is easily seen to
be symmetric or skew-symmetric and we set $\varepsilon({\pi})=\pm 1$
accordingly. In this paper, we show that $\varepsilon{(\pi)}=1$ when $\pi$ is
an Iwahori spherical representation of $G$.


title:
Properties of Surface Plasmon Polaritons on lossy materials: Lifetimes,
  periods and excitation conditions

abstract:
  The possibility to excite Surface Plasmon Polaritons (SPPs) at the interface
between two media depends on the optical properties of both media and
geometrical aspects. Specific conditions allowing the coupling of light with a
plasmon-active interface must be satisfied. Plasmonic effects are well
described in noble metals where the imaginary part of the dielectric
permittivity is often neglected ("perfect medium approximation"). However, some
systems exist for which such approximation cannot be applied, hence requiring a
refinement of the common SPP theory. In this context, several properties of
SPPs such as excitation conditions, period of the electromagnetic field
modulation and SPP lifetime then may strongly deviate from that of the perfect
medium approximation. In this paper, calculations taking into account the
imaginary part of the dielectric permittivities are presented. The model
identifies analytical terms which should not be neglected in the mathematical
description of SPPs on lossy materials. These calculations are applied to
numerous material combinations resulting in a prediction of the corresponding
SPP features. A list of plasmon-active interfaces is provided along with a
quantification of the above mentioned SPP properties in the regime where the
perfect medium approximation is not applicable.


title: Kinetic theory of discontinuous shear thickening

abstract:
  A simple kinetic theory to exhibit a discontinuous shear thickening (DST) is
proposed. The model includes the collision integral and the friction from
environment as well as a thermostat term characterized by $T_{\rm ex}$. The
viscosity of this model is proportional to $\dot\gamma^2$ for large shear rate
$\dot\gamma$, while it is Newtonian for low $\dot\gamma$. The emergence of the
DST is enhanced for lower density and lower nonzero $T_{\rm ex}$.


title: Theoretical approaches to low energy $\bar{K}N$ interactions

abstract:
  We provide a direct comparison of modern theoretical approaches based on the
SU(3) chiral dynamics and describing the low energy $\bar{K}N$ data. The model
predictions for the $\bar{K}N$ amplitudes and pole content of the models are
discussed.


title: On quaternionic complexes over unimodular quaternionic manifolds

abstract:
  Penrose's two-spinor notation for $4$-dimensional Lorentzian manifolds can be
extended to two-component notation for quaternionic manifolds, which is a very
useful tool for calculation. We construct a family of quaternionic complexes
over unimodular quaternionic manifolds by elementary calculation. On complex
quaternionic manifolds, which are essentially the complexification of real
analytic quaternionic K\"ahler manifolds, the existence of these complexes was
established by Baston by using twistor transformations and spectral sequences.
Unimodular quaternionic manifolds constitute a nice and large class of
quaternionic manifolds: the conformal change of a unimodular quaternionic
structure is still unimodular quaternionic and the complexes over such
manifolds are conformally invariant. This class of manifolds, including
quaternionic K\"ahler manifolds, are the real version of torsion-free QCFs
introduced by Bailey and Eastwood. We show the ellipticity of these complexes
and its Hodge-type decomposition. We also obtain a Weitzenb\"ock formula to
establish vanishing of the cohomology groups of these complexes for
quaternionic K\"ahler manifolds with negative scalar curvatures.


title:
Local and long-range realizations of a spin-reorientation surface phase
  transition

abstract:
  The spin reorientation transition of an ultrathin film from perpendicular to
in-plane magnetization is driven by a competition between dipole and anisotropy
energies. \textit{In situ} measurements of the magnetic susceptibility of Fe/2
ML Ni/W(110) films as a function of Fe coverage, made as the films are
deposited at constant temperature, show two clear peaks; one at the long-range
and one at the local realization of the transition. In the long-range
realization, the susceptibility probes the striped domain pattern that is
formed in response to the balance of energetics on a mesoscopic scale. Here the
reorientation transition occurs at a non-integer layer thickness. In the local
realization, the susceptibility probes the response of small islands with
in-plane anisotropy in the 3rd atomic Fe layer that are grown on the 2nd atomic
Fe layer, which has perpendicular anisotropy. It is a response to the local
finite-size, metastable energetics due to discrete steps in thickness. An
excellent quantitative description of the susceptibility data is obtained when
both local and long-range aspects of the spin reorientation transition are
included.


title: Regularized Optimal Transport and the Rot Mover's Distance

abstract:
  This paper presents a unified framework for smooth convex regularization of
discrete optimal transport problems. In this context, the regularized optimal
transport turns out to be equivalent to a matrix nearness problem with respect
to Bregman divergences. Our framework thus naturally generalizes a previously
proposed regularization based on the Boltzmann-Shannon entropy related to the
Kullback-Leibler divergence, and solved with the Sinkhorn-Knopp algorithm. We
call the regularized optimal transport distance the rot mover's distance in
reference to the classical earth mover's distance. We develop two generic
schemes that we respectively call the alternate scaling algorithm and the
non-negative alternate scaling algorithm, to compute efficiently the
regularized optimal plans depending on whether the domain of the regularizer
lies within the non-negative orthant or not. These schemes are based on
Dykstra's algorithm with alternate Bregman projections, and further exploit the
Newton-Raphson method when applied to separable divergences. We enhance the
separable case with a sparse extension to deal with high data dimensions. We
also instantiate our proposed framework and discuss the inherent specificities
for well-known regularizers and statistical divergences in the machine learning
and information geometry communities. Finally, we demonstrate the merits of our
methods with experiments using synthetic data to illustrate the effect of
different regularizers and penalties on the solutions, as well as real-world
data for a pattern recognition application to audio scene classification.


title: The generalized Catalan equation in positive characteristic

abstract:
  Let $K = \mathbb{F}_p(z_1, \ldots, z_r)$ be a finitely generated field over
$\mathbb{F}_p$. In this article we study the generalized Catalan equation $ax^m
+ by^n = 1$ in $x, y \in K$ and integers $m, n > 1$ coprime with $p$. Our main
result shows that there are only finitely many solutions up to the action of
Frobenius.


title:
Exploiting inter-image similarity and ensemble of extreme learners for
  fixation prediction using deep features

abstract:
  This paper presents a novel fixation prediction and saliency modeling
framework based on inter-image similarities and ensemble of Extreme Learning
Machines (ELM). The proposed framework is inspired by two observations, 1) the
contextual information of a scene along with low-level visual cues modulates
attention, 2) the influence of scene memorability on eye movement patterns
caused by the resemblance of a scene to a former visual experience. Motivated
by such observations, we develop a framework that estimates the saliency of a
given image using an ensemble of extreme learners, each trained on an image
similar to the input image. That is, after retrieving a set of similar images
for a given image, a saliency predictor is learnt from each of the images in
the retrieved image set using an ELM, resulting in an ensemble. The saliency of
the given image is then measured in terms of the mean of predicted saliency
value by the ensemble's members.


title:
Dynamic accessibility using Big Data: The role of the changing
  conditions of network congestion and destination attractiveness

abstract: This paper analyses urban accessibility using a fully dynamic approach.


title:
Hybrid-Density Functional Theory Study on Band Structures of
  Tetradymite-Bi2Te3, Sb2Te3, Bi2Se3, and Sb2Se3 Thermoelectric Materials

abstract:
  The low energy band structure near the band gap determines the electrical
performance of thermoelectric materials. Here, by using the hybrid-density
functional theory (hybrid-DFT) calculations, we calculate the low energy band
structure of Bi2Te3, Sb2Te3, Bi2Se3 and Sb2Se3 in tetradymite phase. We find
that the band structure characteristics are very sensitive the selection of the
exchange energy functional. The predictability of the band gaps and band
degeneracies is not enhanced in hybrid-DFT calculations, as compared to DFT
calculations. The poor prediction of low energy band structures is originated
from the poor prediction of interlayer distances and the high structure
sensitivity on the band gap. We conclude that the hybrid DFT calculations are
not superior to DFT calculations when predicting band structures of tetradymite
Bi2Te3, Sb2Te3, Bi2Se3 and Sb2Se3 thermoelectric materials.


title: Spatio-temporal extreme events in a laser with a saturable absorber

abstract:
  We study extreme events occurring in the transverse $(x,y)$ section of the
field emitted by a broad-area semiconductor laser with a saturable absorber.
The spatio-temporal events on which we perform the statistical analysis are
identified as maxima of the field intensity in the 3D space $(x,y,t)$. We
identify regions in the parameter space where extreme events are more likely to
occur and we study the connection of those extreme events with the cavity
solitons that are known to exist in the same system, both stationary and
self-pulsing.


title: Change-point Detection Methods for Body-Worn Video

abstract:
  Body-worn video (BWV) cameras are increasingly utilized by police departments
to provide a record of police-public interactions. However, large-scale BWV
deployment produces terabytes of data per week, necessitating the development
of effective computational methods to identify salient changes in video. In
work carried out at the 2016 RIPS program at IPAM, UCLA, we present a novel
two-stage framework for video change-point detection. First, we employ
state-of-the-art machine learning methods including convolutional neural
networks and support vector machines for scene classification. We then develop
and compare change-point detection algorithms utilizing mean squared-error
minimization, forecasting methods, hidden Markov models, and maximum likelihood
estimation to identify noteworthy changes. We test our framework on detection
of vehicle exits and entrances in a BWV data set provided by the Los Angeles
Police Department and achieve over 90% recall and nearly 70% precision --
demonstrating robustness to rapid scene changes, extreme luminance differences,
and frequent camera occlusions.


title:
Reasoning with Memory Augmented Neural Networks for Language
  Comprehension

abstract:
  Hypothesis testing is an important cognitive process that supports human
reasoning. In this paper, we introduce a computational hypothesis testing
approach based on memory augmented neural networks. Our approach involves a
hypothesis testing loop that reconsiders and progressively refines a previously
formed hypothesis in order to generate new hypotheses to test. We apply the
proposed approach to language comprehension task by using Neural Semantic
Encoders (NSE). Our NSE models achieve the state-of-the-art results showing an
absolute improvement of 1.2% to 2.6% accuracy over previous results obtained by
single and ensemble systems on standard machine comprehension benchmarks such
as the Children's Book Test (CBT) and Who-Did-What (WDW) news article datasets.


title: Optimal design of mixtures of ferromagnetic interactions

abstract:
  We provide a general framework for the optimal design of surface energies on
networks. We prove sharp bounds for the homogenization of discrete systems
describing mixtures of ferromagnetic interactions by constructing optimal
microgeometries, and we prove a localization principle which allows to reduce
to the periodic setting in the general nonperiodic case.


title: Dyson--Schwinger Approach to Hamiltonian QCD

abstract:
  Dyson--Schwinger equations are an established, powerful non-perturbative tool
for QCD. In the Hamiltonian formulation of a quantum field theory they can be
used to perform variational calculations with non-Gaussian wave functionals. By
means of the DSEs the various $n$-point functions, needed in expectation values
of observables like the Hamilton operator, can be thus expressed in terms of
the variational kernels of our trial ansatz. Equations of motion for these
variational kernels are derived by minimizing the energy density and solved
numerically.


title: Matchings in Geometric Graphs

abstract:
  A geometric graph is a graph whose vertex set is a set of points in the plane
and whose edge set contains straight-line segments. A matching in a graph is a
subset of edges of the graph with no shared vertices. A matching is called
perfect if it matches all the vertices of the underling graph. A geometric
matching is a matching in a geometric graph. In this thesis, we study matching
problems in various geometric graphs. Among the family of geometric graphs we
look at complete graphs, complete bipartite graphs, complete multipartite
graphs, Delaunay graphs, Gabriel graphs, and $\Theta$-graphs. The classical
matching problem is to find a matching of maximum size in a given graph. We
study this problem as well as some of its variants on geometric graphs. The
bottleneck matching problem is to find a maximum matching that minimizes the
length of the longest edge. The plane matching problem is to find a maximum
matching so that the edges in the matching are pairwise non-crossing. A
geometric matching is strong with respect to a given shape $S$ if we can assign
to each edge in the matching a scaled version of $S$ such that the shapes
representing the edges are pairwise disjoint. The strong matching problem is to
find a maximum strong matching with respect to a given shape. The matching
packing problem is to pack as many edge-disjoint perfect matchings as possible
into a geometric graph. We study these problems and establish lower and upper
bounds on the size of different kinds of matchings in various geometric graphs.
We also present algorithms for computing such matchings. Some of the presented
bounds are tight, while the others need to be sharpened.


title: The Asymptotic Capacity of the Optical Fiber

abstract:
  It is shown that signal energy is the only available degree-of-freedom (DOF)
for fiber-optic transmission as the input power tends to infinity. With $n$
signal DOFs at the input, $n-1$ DOFs are asymptotically lost to signal-noise
interactions. The main observation is that, nonlinearity introduces a
multiplicative noise in the channel, similar to fading in wireless channels.
The channel is viewed in the spherical coordinate system, where signal vector
$\underline{X}\in\mathbb{C}^n$ is represented in terms of its norm
$|\underline{X}|$ and direction $\underline{\hat{X}}$. The multiplicative noise
causes signal direction $\underline{\hat{X}}$ to vary randomly on the surface
of the unit $(2n-1)$-sphere in $\mathbb{C}^{n}$, in such a way that the
effective area of the support of $\underline{\hat{X}}$ does not vanish as
$|\underline{X}|\rightarrow\infty$. On the other hand, the surface area of the
sphere is finite, so that $\underline{\hat{X}}$ carries finite information.
This observation is used to show several results. Firstly, let $\mathcal
C(\mathcal P)$ be the capacity of a discrete-time periodic model of the optical
fiber with distributed noise and frequency-dependent loss, as a function of the
average input power $\mathcal P$. It is shown that asymptotically as $\mathcal
P\rightarrow\infty$, $\mathcal C=\frac{1}{n}\log\bigl(\log\mathcal P\bigr)+c$,
where $n$ is the dimension of the input signal space and $c$ is a bounded
number. In particular, $\lim_{\mathcal P\rightarrow\infty}\mathcal C(\mathcal
P)=\infty$ in finite-dimensional periodic models. Secondly, it is shown that
capacity saturates to a constant in infinite-dimensional models where
$n=\infty$.


title: Magnetic Order-Disorder Transitions on a 1/3 - Depleted Square Lattice

abstract:
  Quantum Monte Carlo simulations are used to study the magnetic and transport
properties of the Hubbard Model, and its strong coupling Heisenberg limit, on a
one-third depleted square lattice. This is the geometry occupied, after charge
ordering, by the spin-$\frac{1}{2}$ Ni$^{1+}$ atoms in a single layer of the
nickelate materials La$_4$Ni$_3$O$_8$ and (predicted) La$_3$Ni$_2$O$_6$. Our
model is also a description of strained graphene, where a honeycomb lattice has
bond strengths which are inequivalent. For the Heisenberg case, we determine
the location of the quantum critical point (QCP) where there is an onset of
long range antiferromagnetic order (LRAFO), and the magnitude of the order
parameter, and then compare with results of spin wave theory. An ordered phase
also exists when electrons are itinerant. In this case, the growth in the
antiferromagnetic structure factor coincides with the transition from band
insulator to metal in the absence of interactions.


title:
On the detectability of solar-like oscillations with the NASA TESS
  mission

abstract:
  The upcoming NASA TESS mission will perform an all-sky survey for planets
transiting bright nearby stars. In addition, its excellent photometric
precision will enable asteroseismology of solar-type and red-giant stars. We
apply a newly developed detection test along a sequence of stellar evolutionary
tracks in order to predict the detectability of solar-like oscillations with
TESS.


title:
Efficient Estimation of Compressible State-Space Models with Application
  to Calcium Signal Deconvolution

abstract:
  In this paper, we consider linear state-space models with compressible
innovations and convergent transition matrices in order to model
spatiotemporally sparse transient events. We perform parameter and state
estimation using a dynamic compressed sensing framework and develop an
efficient solution consisting of two nested Expectation-Maximization (EM)
algorithms. Under suitable sparsity assumptions on the innovations, we prove
recovery guarantees and derive confidence bounds for the state estimates. We
provide simulation studies as well as application to spike deconvolution from
calcium imaging data which verify our theoretical results and show significant
improvement over existing algorithms.

categories: stat.ML cs.CV cs.IT math.DS math.IT math.ST stat.TH


title:
Gaussian process modeling in approximate Bayesian computation to
  estimate horizontal gene transfer in bacteria

abstract:
  Approximate Bayesian computation (ABC) can be used for model fitting when the
likelihood function is intractable but simulating from the model is feasible.
However, even a single evaluation of a complex model may take several hours,
limiting the number of model evaluations available. Modelling the discrepancy
between the simulated and observed data using a Gaussian process (GP) can be
used to reduce the number of model evaluations required by ABC, but the
sensitivity of this approach to a specific GP formulation has not yet been
thoroughly investigated. We begin with a comprehensive empirical evaluation of
using GPs in ABC, including various transformations of the discrepancies and
two novel GP formulations. Our results indicate the choice of GP may
significantly affect the accuracy of the estimated posterior distribution.
Selection of an appropriate GP model is thus important. We formulate expected
utility to measure the accuracy of classifying discrepancies below or above the
ABC threshold, and show that it can be used to automate the GP model selection
step. Finally, based on the understanding gained with toy examples, we fit a
population genetic model for bacteria, providing insight into horizontal gene
transfer events within the population and from external origins.


title: Tracing water vapor and ice during dust growth

abstract:
  The processes that govern the evolution of dust and water (in the form of
vapor or ice) in protoplanetary disks are intimately connected. We have
developed a model that simulates dust coagulation, dust dynamics (settling,
turbulent mixing), vapor diffusion, and condensation/sublimation of volatiles
onto grains in a vertical column of a protoplanetary disk. We employ the model
to study how dust growth and dynamics influence the vertical distribution of
water vapor and water ice in the region just outside the radial snowline. Our
main finding is that coagulation (boosted by the enhanced stickiness of icy
grains) and the ensuing vertical settling of solids results in water vapor
being depleted, but not totally removed, from the region above the snowline on
a timescale commensurate with the vertical turbulent mixing timescale.
Depending on the strength of the turbulence and the temperature, the depletion
can reach factors of up to ${\sim}50$ in the disk atmosphere. In our isothermal
column, this vapor depletion results in the vertical snowline moving closer to
the midplane (by up to 2 gas scale heights) and the gas-phase C/O ratio above
the vertical snowline increasing. Our findings illustrate the importance of
dynamical effects and the need for understanding coevolutionary dynamics of gas
and solids in planet-forming environments.


title: Quantum gravitational effects on boundary

abstract:
  Quantum gravitational effects may hold the key to some of the outstanding
problems in theoretical physics. In this work we analyze the perturbative
quantum effects on the boundary of a gravitational system and Dirichlet
boundary condtion imposed at the classical level. Our analysis reveals that for
a black hole solution there exists a clash between the quantum effects and
Dirichlet boundary condition: the solution of the one-particle-irreducible
(1PI) action no longer obeys the Dirichlet boundary condition. The analysis
also suggests that the violation of the Dirichlet boundary condition should be
tied with a certain mechanism of information storage on the boundary.


title:
Towards Partial Compositeness on the Lattice: Baryons with Fermions in
  Multiple Representations

abstract:
  We describe our recent lattice study of SU(4) gauge theory with fermions in
the fundamental and sextet representations. In this theory, a new type of
baryon consists of quarks in both representations. The spectrum of these
"chimera baryons" has a straightforward interpretation in terms of a
non-relativistic quark model based on SU(4). Our results are particularly
relevant to composite Higgs models in which the top quark is partially
composite.


title: Clustering and melting in a wet granular monolayer

abstract:
  We investigate experimentally the collective behavior of a wet granular
monolayer under vertical vibrations. The spherical particles are partially wet
such that there are short-ranged attractive interactions between adjacent
particles. As the vibration strength increases, clustering, reorganizing and
melting regimes are identified subsequently through a characterization with the
bond-orientational order parameters and the mean kinetic energy of the
particles. The melting transition is found to be a continuous process starting
from the defects inside the crystal.


title: Emergence of Digital Twins

abstract:
  Multiple forms of digital transformation are imminent. Digital Twins
represent one concept. It is gaining momentum because it may offer real-time
transparency. Rapid diffusion of digital duplicates faces hurdles due to lack
of semantic interoperability between architectures, standards and ontologies.
The technologies necessary for automated discovery are in short supply.
Progression of the field depends on convergence of information technology,
operational technology and protocol-agnostic telecommunications. Making sense
of the data, ability to curate data and perform data analytics at the edge (or
mist rather than in the fog or cloud) is key to value. Delivering engines to
the edge are crucial for analytics at the edge when latency is critical. The
confluence of these and other factors may chart the future path for Digital
Twins. The number of unknown unknowns and the known unknowns in this process
makes it imperative to create global infrastructures and organize groups to
pursue the development of fundamental building blocks and new ideas through
research.


title: Ten Blue Links on Mars

abstract:
  This paper explores a simple question: How would we provide a high-quality
search experience on Mars, where the fundamental physical limit is
speed-of-light propagation delays on the order of tens of minutes? On Earth,
users are accustomed to nearly instantaneous response times from search
engines. Is it possible to overcome orders-of-magnitude longer latency to
provide a tolerable user experience on Mars? In this paper, we formulate the
searching from Mars problem as a tradeoff between "effort" (waiting for
responses from Earth) and "data transfer" (pre-fetching or caching data on
Mars). The contribution of our work is articulating this design space and
presenting two case studies that explore the effectiveness of baseline
techniques, using publicly available data from the TREC Total Recall and
Sessions Tracks. We intend for this research problem to be aspirational and
inspirational - even if one is not convinced by the premise of Mars
colonization, there are Earth-based scenarios such as searching from a rural
village in India that share similar constraints, thus making the problem worthy
of exploration and attention from researchers.


title:
Fast and guaranteed blind multichannel deconvolution under a bilinear
  system model

abstract:
  We consider the multichannel blind deconvolution problem where we observe the
output of multiple channels that are all excited with the same unknown input.
From these observations, we wish to estimate the impulse responses of each of
the channels. We show that this problem is well-posed if the channels follow a
bilinear model where the ensemble of channel responses is modeled as lying in a
low-dimensional subspace but with each channel modulated by an independent
gain. Under this model, we show how the channel estimates can be found by
minimizing a quadratic functional over a non-convex set.
  We analyze two methods for solving this non-convex program, and provide
performance guarantees for each. The first is a method of alternating
eigenvectors that breaks the program down into a series of eigenvalue problems.
The second is a truncated power iteration, which can roughly be interpreted as
a method for finding the largest eigenvector of a symmetric matrix with the
additional constraint that it adheres to our bilinear model. As with most
non-convex optimization algorithms, the performance of both of these algorithms
is highly dependent on having a good starting point. We show how such a
starting point can be constructed from the channel measurements.
  Our performance guarantees are non-asymptotic, and provide a sufficient
condition on the number of samples observed per channel in order to guarantee
channel estimates of a certain accuracy. Our analysis uses a model with a
"generic" subspace that is drawn at random, and we show the performance bounds
hold with high probability. Mathematically, the key estimates are derived by
quantifying how well the eigenvectors of certain random matrices approximate
the eigenvectors of their mean.
  We also present a series of numerical results demonstrating that the
empirical performance is consistent with the presented theory.


title: On lexicographic approximations of integer programs

abstract:
  We use the lexicographic order to define a hierarchy of primal and dual
bounds on the optimum of a bounded integer program. These bounds are
constructed using lex maximal and minimal feasible points taken under different
permutations. Their strength is analyzed and it is shown that a family of
primal bounds is tight for any $0\backslash 1$ program with nonnegative linear
objective, and a different family of dual bounds is tight for any packing- or
covering-type $0\backslash 1$ program with an arbitrary linear objective. The
former result yields a structural characterization for the optimum of
$0\backslash 1$ programs, with connections to matroid optimization, and a
heuristic for general integer programs. The latter result implies a stronger
polyhedral representation for the integer feasible points and a new approach
for deriving strong valid inequalities to the integer hull. Since the
construction of our bounds depends on the computation of lex optima, we derive
explicit formulae for lex optima of some special polytopes, such as polytopes
that are monotone with respect to each variable, and integral polymatroids and
their base polytopes. We also classify $\mathrm{P}$ and
$\mathrm{NP}$-$\mathrm{hard}$ cases of computing lex bounds and lex optima.


title: Matrix Model of Chern-Simons Matter Theories Beyond The Spherical Limit

abstract:
  A class of matrix models which arises as partition function in U(N)
Chern-Simons matter theories on three sphere is investigated. Employing the
standard technique of the 1/N expansion we solve the system beyond the planar
limit. In particular we study a case where the matrix model potential has 1/N
correction and give a general solution thereof up to the order of 1/N^2. We
confirm that the general solution correctly reproduces the past exact result of
the free energy up to the order in the case of pure Chern-Simons theory. We
also apply to the matrix model of N=2 Chern-Simons theory with arbitrary
numbers of fundamental chiral multiplets and anti-fundamental ones, which does
not admit the Fermi gas analysis in general.


title: The Berry-Keating operator on a lattice

abstract:
  We construct and study a version of the Berry-Keating operator with a
built-in truncation of the phase space, which we choose to be a two-dimensional
torus. The operator is a Weyl quantisation of the classical Hamiltonian for an
inverted harmonic oscillator, producing a difference operator on a finite,
periodic lattice. We investigate the continuum and the infinite-volume limit of
our model in conjunction with the semiclassical limit. Using semiclassical
methods, we show that a specific combination of the limits leads to a
logarithmic mean spectral density as it was anticipated by Berry and Keating.


title:
Generalized Interval-valued OWA Operators with Interval Weights Derived
  from Interval-valued Overlap Functions

abstract:
  In this work we extend to the interval-valued setting the notion of an
overlap functions and we discuss a method which makes use of interval-valued
overlap functions for constructing OWA operators with interval-valued weights.
. Some properties of interval-valued overlap functions and the derived
interval-valued OWA operators are analysed. We specially focus on the
homogeneity and migrativity properties.


title:
Packing dimension of images and graphs of Gaussian random fields with
  drift

abstract:
  Let $X=\{(X_1(t),\dots,X_d(t)): t\in \mathbb{R}^n\}$ be a Gaussian random
field in $\mathbb{R}^d$ such that $X_1,\dots,X_d$ are independent, centered
Gaussian random fields with continuous sample paths. Let $f\colon
\mathbb{R}^n\to \mathbb{R}^d$ be a Borel map and let $A\subset \mathbb{R}^n$ be
an analytic set. The main goal of the paper is to determine the almost sure
value of the packing dimension of the image and graph of $X+f$ restricted to
$A$ under a very mild assumption. This generalizes a result of Du, Miao, Wu and
Xiao, who calculated the packing dimension of $X(A)$ if $X_1,\dots,X_d$ are
independent copies of the same Gaussian random field $X_0$. Provided that $X$
is a fractional Brownian motion, our result is new even if $n=d=1$ and $f$ is
continuous, and even if $f\equiv 0$ in the case of graphs.
  For a fractional Brownian motion $X$ we also obtain the sharp lower bound for
the packing dimension of the graph of $X$ over $A$ in terms of the Hurst index
of $X$ and the packing dimension of $A$. The analogous result for images was
obtained by Talagrand and Xiao.


title:
ORB-SLAM2: an Open-Source SLAM System for Monocular, Stereo and RGB-D
  Cameras

abstract:
  We present ORB-SLAM2 a complete SLAM system for monocular, stereo and RGB-D
cameras, including map reuse, loop closing and relocalization capabilities. The
system works in real-time on standard CPUs in a wide variety of environments
from small hand-held indoors sequences, to drones flying in industrial
environments and cars driving around a city. Our back-end based on bundle
adjustment with monocular and stereo observations allows for accurate
trajectory estimation with metric scale. Our system includes a lightweight
localization mode that leverages visual odometry tracks for unmapped regions
and matches to map points that allow for zero-drift localization. The
evaluation on 29 popular public sequences shows that our method achieves
state-of-the-art accuracy, being in most cases the most accurate SLAM solution.
We publish the source code, not only for the benefit of the SLAM community, but
with the aim of being an out-of-the-box SLAM solution for researchers in other
fields.


title:
Nonperturbative functional renormalization-group approach to transport
  in the vicinity of a $(2+1)$-dimensional O($N$)-symmetric quantum critical
  point

abstract:
  Using a nonperturbative functional renormalization-group approach to the
two-dimensional quantum O($N$) model, we compute the low-frequency limit
$\omega\to 0$ of the zero-temperature conductivity in the vicinity of the
quantum critical point. Our results are obtained from a derivative expansion to
second order of a scale-dependent effective action in the presence of an
external (i.e., non-dynamical) non-Abelian gauge field. While in the disordered
phase the conductivity tensor $\sigma(\omega)$ is diagonal, in the ordered
phase it is defined, when $N\geq 3$, by two independent elements, $\sigma_{\rm
A}(\omega)$ and $\sigma_{\rm B}(\omega)$, respectively associated to SO($N$)
rotations which do and do not change the direction of the order parameter. For
$N=2$, the conductivity in the ordered phase reduces to a single component
$\sigma_{\rm A}(\omega)$. We show that $\lim_{\omega\to
0}\sigma(\omega,\delta)\sigma_{\rm A}(\omega,-\delta)/\sigma_q^2$ is a
universal number which we compute as a function of $N$ ($\delta$ measures the
distance to the quantum critical point, $q$ is the charge and $\sigma_q=q^2/h$
the quantum of conductance). On the other hand we argue that the ratio
$\sigma_{\rm B}(\omega\to 0)/\sigma_q$ is universal in the whole ordered phase,
independent of $N$ and, when $N\to\infty$, equal to the universal conductivity
$\sigma^*/\sigma_q$ at the quantum critical point.

categories: cond-mat.str-el cond-mat.quant-gas cond-mat.stat-mech hep-th


title: Interacting Brownian dynamics in a nonequilibrium particle bath

abstract:
  We set up a mesoscopic theory for interacting Brownian particles embedded in
a nonequilibrium environment, starting from the microscopic interacting
many-body theory. Using nonequilibrium linear response theory, we characterize
the effective dynamical interactions on the mesoscopic scale and the statistics
of the nonequilibrium environmental noise, arising upon integrating out the
fast degrees of freedom. As hallmarks of nonequilibrium, the breakdown of the
fluctuation-dissipation and action-reaction relations for Brownian degrees of
freedom are exemplified with two prototypical models for the environment,
namely, active Brownian particles and stirred colloids.


title: Inflation and reheating in scale-invariant scalar-tensor gravity

abstract:
  We consider the scale-invariant inflationary model studied in [1]. The
Lagrangian includes all the scale-invariant operators that can be built with
combinations of $R$, $R^2$ and one scalar field. The equations of motion show
that the symmetry is spontaneously broken after an arbitrarily long
inflationary period and a fundamental mass scale is generated. Upon symmetry
breaking, and in the Jordan frame, both Hubble function and the scalar field
undergo damped oscillations that can eventually amplify Standard Model fields
and reheat the Universe. In the present work, we study in detail inflation and
the reheating mechanism of this model in the Einstein frame and we compare some
of the results with the latest observational data.


title: Competition in growth and urns

abstract:
  We study survival among two competing types in two settings: a planar growth
model related to two-neighbour bootstrap percolation, and a system of urns with
graph-based interactions. In the planar growth model, uncoloured sites are
given a colour at rate $0$, $1$ or $\infty$, depending on whether they have
zero, one, or at least two neighbours of that colour. In the urn scheme, each
vertex of a graph $G$ has an associated urn containing some number of either
blue or red balls (but not both). At each time step, a ball is chosen uniformly
at random from all those currently present in the system, a ball of the same
colour is added to each neighbouring urn, and balls in the same urn but of
different colours annihilate on a one-for-one basis. We show that, for every
connected graph $G$ and every initial configuration, only one colour survives
almost surely. As a corollary, we deduce that in the two-type growth model on
$\mathbb{Z}^2$, one of the colours only infects a finite number of sites with
probability one. We also discuss generalisations to higher dimensions and
multi-type processes, and list a number of open problems and conjectures.


title: The Gaia-ESO Survey: calibration strategy

abstract:
  The Gaia-ESO survey (GES) is now in its fifth and last year of observations,
and has already produced tens of thousands of high-quality spectra of stars in
all Milky Way components. This paper presents the strategy behind the selection
of astrophysical calibration targets, ensuring that all GES results on radial
velocities, atmospheric parameters, and chemical abundance ratios will be both
internally consistent and easily comparable with other literature results,
especially from other large spectroscopic surveys and from Gaia. The
calibration of GES is particularly delicate because of: (i) the large space of
parameters covered by its targets, ranging from dwarfs to giants, from O to M
stars, and with a large range of metallicities, as well as including fast
rotators, emission line objects, stars affected by veiling and so on; (ii) the
variety of observing setups, with different wavelength ranges and resolution;
and (iii) the choice of analyzing the data with many different state-of-the art
methods, each stronger in a different region of the parameter space, which
ensures a better understanding of systematic uncertainties. An overview of the
GES calibration and homogenization strategy is also given, along with some
examples of the usage and results of calibrators in GES iDR4 - the fourth
internal GES data release, that will form the basis of the next GES public data
release. The agreement between GES iDR4 recommended values and reference values
for the calibrating objects are very satisfactory. The average offsets and
spreads are generally compatible with the GES measurement errors, which in iDR4
data already meet the requirements set by the main GES scientific goals.


title:
Science with the space-based interferometer LISA. IV: Probing inflation
  with gravitational waves

abstract:
  We investigate the potential for the LISA space-based interferometer to
detect the stochastic gravitational wave background produced from different
mechanisms during inflation. Focusing on well-motivated scenarios, we study the
resulting contributions from particle production during inflation, inflationary
spectator fields with varying speed of sound, effective field theories of
inflation with specific patterns of symmetry breaking and models leading to the
formation of primordial black holes. The projected sensitivities of LISA are
used in a model-independent way for various detector designs and
configurations. We demonstrate that LISA is able to probe these well-motivated
inflationary scenarios beyond the irreducible vacuum tensor modes expected from
any inflationary background.


title:
Generation of Schr\"odinger's cat states in a planar semiconductor
  heterostructure

abstract:
  We propose a nanodevice based on a typical planar semiconductor
heterostructure with lateral confinement potential created by voltages applied
to local electrodes. We show how to obtain near parabolical confinement along
the nanodevice, and how to use coherent states of the harmonic oscillator for
spatial separation of electron densities corresponding to opposite spin
directions. In such a way, an entangled state of Schr\"odinger's cat type is
created. We performed simulations of a realistic nanodevice model by numerical
solving the time-dependent Schr\"odinger's equation together with simultaneous
tracking of the controllable confinement potential via solution of the
Poisson's equation at every time step.


title: An Extended Neo-Fuzzy Neuron and its Adaptive Learning Algorithm

abstract:
  A modification of the neo-fuzzy neuron is proposed (an extended neo-fuzzy
neuron (ENFN)) that is characterized by improved approximating properties. An
adaptive learning algorithm is proposed that has both tracking and smoothing
properties. An ENFN distinctive feature is its computational simplicity
compared to other artificial neural networks and neuro-fuzzy systems.


title: An Evolving Cascade System Based on A Set Of Neo Fuzzy Nodes

abstract:
  Neo-fuzzy elements are used as nodes for an evolving cascade system. The
proposed system can tune both its parameters and architecture in an online
mode. It can be used for solving a wide range of Data Mining tasks (namely time
series forecasting). The evolving cascade system with neo-fuzzy nodes can
process rather large data sets with high speed and effectiveness.


title:
A Multidimensional Cascade Neuro-Fuzzy System with Neuron Pool
  Optimization in Each Cascade

abstract:
  A new architecture and learning algorithms for the multidimensional hybrid
cascade neural network with neuron pool optimization in each cascade are
proposed in this paper. The proposed system differs from the well-known cascade
systems in its capability to process multidimensional time series in an online
mode, which makes it possible to process non-stationary stochastic and chaotic
signals with the required accuracy. Compared to conventional analogs, the
proposed system provides computational simplicity and possesses both tracking
and filtering capabilities.


title:
Adaptive Forecasting of Non-Stationary Nonlinear Time Series Based on
  the Evolving Weighted Neuro-Neo-Fuzzy-ANARX-Model

abstract:
  An evolving weighted neuro-neo-fuzzy-ANARX model and its learning procedures
are introduced in the article. This system is basically used for time series
forecasting. This system may be considered as a pool of elements that process
data in a parallel manner. The proposed evolving system may provide online
processing data streams.


title: Renormalization Scheme Dependence and Renormalization Group Summation

abstract:
  We consider logarithmic contributions to the free energy, instanton effective
action and Laplace sum rules in QCD that are a consequence of radiative
corrections. Upon summing these contributions by using the renormalization
group, all dependence on the renormalization scale parameter $\mu$ cancels. The
renormalization scheme dependence in these processes is examined, and a
renormalization scheme is found in which the effect of higher order radiative
corrections is absorbed by the behaviour of the running coupling.


title: An Evolving Neuro-Fuzzy System with Online Learning/Self-learning

abstract:
  An architecture of a new neuro-fuzzy system is proposed. The basic idea of
this approach is to tune both synaptic weights and membership functions with
the help of the supervised learning and self-learning paradigms. The approach
to solving the problem has to do with evolving online neuro-fuzzy systems that
can process data under uncertainty conditions. The results prove the
effectiveness of the developed architecture and the learning procedure.


title: Generalization of Frobenius' theorem for group determinants

abstract:
  Frobenius built a representation theory of finite groups in the process of
obtaining the irreducible factorization of the group determinant. Here, we give
a generalization of Frobenius' theorem. The generalization leads to a corollary
on irreducible representations of finite groups.


title:
An Ensemble of Adaptive Neuro-Fuzzy Kohonen Networks for Online Data
  Stream Fuzzy Clustering

abstract:
  A new approach to data stream clustering with the help of an ensemble of
adaptive neuro-fuzzy systems is proposed. The proposed ensemble is formed with
adaptive neuro-fuzzy self-organizing Kohonen maps in a parallel processing
mode. A final result is chosen by the best neuro-fuzzy self-organizing Kohonen
map.


title:
Spheroidal and ellipsoidal harmonic expansions of the gravitational
  potential of small Solar System bodies. Case study: Comet
  67P/Churyumov-Gerasimenko

abstract:
  Gravitational features are a fundamental source of information to learn more
about the interior structure and composition of planets, moons, asteroids and
comets. Gravitational field modeling typically approximates the target body
with a sphere, leading to a representation in spherical harmonics. However,
small celestial bodies are often irregular in shape, and hence poorly
approximated by a sphere. A much better suited geometrical fit is achieved by a
tri-axial ellipsoid. This is also mirrored in the fact that the associated
harmonic expansion (ellipsoidal harmonics) shows a significantly better
convergence behavior as opposed to spherical harmonics. Unfortunately, complex
mathematics and numerical problems (arithmetic overflow) so far severely
limited the applicability of ellipsoidal harmonics. In this paper, we present a
method that allows expanding ellipsoidal harmonics to a considerably higher
degree compared to existing techniques. We apply this novel approach to model
the gravitational field of comet 67P, the final target of the Rosetta mission.
The comparison of results based on the ellipsoidal parameterization with those
based on the spheroidal and spherical approximations reveals that the latter is
clearly inferior; the spheroidal solution, on the other hand, is virtually just
as accurate as the ellipsoidal one. Finally, in order to generalize our
findings, we assess the gravitational field modeling performance for some 400
small bodies in the solar system. From this investigation we generally conclude
that the spheroidal representation is an attractive alternative to the complex
ellipsoidal parameterization on the one hand, and the inadequate spherical
representation on the other hand.


title:
Utilization of Deep Reinforcement Learning for saccadic-based object
  visual search

abstract:
  The paper focuses on the problem of learning saccades enabling visual object
search. The developed system combines reinforcement learning with a neural
network for learning to predict the possible outcomes of its actions. We
validated the solution in three types of environment consisting of
(pseudo)-randomly generated matrices of digits. The experimental verification
is followed by the discussion regarding elements required by systems mimicking
the fovea movement and possible further research directions.


title: Chromatic Effect for THz Generation in a Novel Wave-front Tilt Scheme

abstract:
  Deriving single or few cycle terahertz pulse (THz) by intense femtosecond
laser through cascaded optical rectification in electro-optic crystals is a
crucial technique in cutting-edge time-resolved spectroscopy to characterize
micro-scale structures and ultrafast dynamics. In the past decade, lithium
niobate (LN) crystal implementation of wave-front tilt scheme has been
prevalently used, while painstaking efforts have been invested in order to
achieve higher THz conversion efficiency. In this research we developed a brand
new type of LN crystal possessing dual-face-cut and Brewster coupling, and
conducted experimental and simulative investigation systematically to optimize
the multi-dimensionally entangled parameters in THz generation, predicting the
extreme conversion efficiency of 10% is potentially promising at the THz
absorption coefficient of 0.5cm-1. More remarkably, we first discovered that
the chirp of the driving laser pulse plays a decisive role in the wave-front
tilt scheme, and the THz generation efficiency could be enhanced tremendously
by applying an appropriate chirp.


title: An Image Dataset of Text Patches in Everyday Scenes

abstract:
  This paper describes a dataset containing small images of text from everyday
scenes. The purpose of the dataset is to support the development of new
automated systems that can detect and analyze text. Although much research has
been devoted to text detection and recognition in scanned documents, relatively
little attention has been given to text detection in other types of images,
such as photographs that are posted on social-media sites. This new dataset,
known as COCO-Text-Patch, contains approximately 354,000 small images that are
each labeled as "text" or "non-text". This dataset particularly addresses the
problem of text verification, which is an essential stage in the end-to-end
text detection and recognition pipeline. In order to evaluate the utility of
this dataset, it has been used to train two deep convolution neural networks to
distinguish text from non-text. One network is inspired by the GoogLeNet
architecture, and the second one is based on CaffeNet. Accuracy levels of 90.2%
and 90.9% were obtained using the two networks, respectively. All of the
images, source code, and deep-learning trained models described in this paper
will be publicly available


title: Cryptography with right-angled Artin groups

abstract:
  In this paper we propose right-angled Artin groups as a platform for secret
sharing schemes based on the efficiency (linear time) of the word problem.
Inspired by previous work of Grigoriev-Shpilrain in the context of graphs, we
define two new problems: Subgroup Isomorphism Problem and Group Homomorphism
Problem. Based on them, we also propose two new authentication schemes. For
right-angled Artin groups, the Group Homomorphism and Graph Homomorphism
problems are equivalent, and the later is known to be NP-complete. In the case
of the Subgroup Isomorphism problem, we bring some results due to Bridson who
shows there are right-angled Artin groups in which this problem is unsolvable.


title:
Representation of dynamic spatial phenomena: The daily car accessibility
  in London

abstract:
  This paper uses traditional maps in animations to show traffic congestion
effects in London


title:
Information Overload in Group Communication: From Conversation to
  Cacophony in the Twitch Chat

abstract:
  Online communication channels, especially social web platforms, are rapidly
replacing traditional ones. Online platforms allow users to overcome physical
barriers, enabling worldwide participation. However, the power of online
communication bears an important negative consequence --- we are exposed to too
much information to process. Too many participants, for example, can turn
online public spaces into noisy, overcrowded fora where no meaningful
conversation can be held. Here we analyze a large dataset of public chat logs
from Twitch, a popular video streaming platform, in order to examine how
information overload affects online group communication. We measure structural
and textual features of conversations such as user output, interaction, and
information content per message across a wide range of information loads. Our
analysis reveals the existence of a transition from a conversational state to a
cacophony --- a state of overload with lower user participation, more
copy-pasted messages, and less information per message. These results hold both
on average and at the individual level for the majority of users. This study
provides a quantitative basis for further studies of the social effects of
information overload, and may guide the design of more resilient online
communication systems.


title: Authorship Attribution Based on Life-Like Network Automata

abstract:
  The authorship attribution is a problem of considerable practical and
technical interest. Several methods have been designed to infer the authorship
of disputed documents in multiple contexts. While traditional statistical
methods based solely on word counts and related measurements have provided a
simple, yet effective solution in particular cases; they are prone to
manipulation. Recently, texts have been successfully modeled as networks, where
words are represented by nodes linked according to textual similarity
measurements. Such models are useful to identify informative topological
patterns for the authorship recognition task. However, there is no consensus on
which measurements should be used. Thus, we proposed a novel method to
characterize text networks, by considering both topological and dynamical
aspects of networks. Using concepts and methods from cellular automata theory,
we devised a strategy to grasp informative spatio-temporal patterns from this
model. Our experiments revealed an outperformance over traditional analysis
relying only on topological measurements. Remarkably, we have found a
dependence of pre-processing steps (such as the lemmatization) on the obtained
results, a feature that has mostly been disregarded in related works. The
optimized results obtained here pave the way for a better characterization of
textual networks.


title: Security of quantum key distribution with iterative sifting

abstract:
  Several quantum key distribution (QKD) protocols employ iterative sifting.
After each quantum transmission round, Alice and Bob disclose part of their
setting information (including their basis choices) for the detected signals.
The quantum phase of the protocol then ends when the numbers of detected
signals per basis exceed certain pre-agreed threshold values. Recently,
however, Pfister et al. [New J. Phys. 18 053001 (2016)] showed that iterative
sifting makes QKD insecure, especially in the finite key regime, if the
parameter estimation for privacy amplification uses the random sampling theory.
This implies that a number of existing finite key security proofs could be
flawed and cannot guarantee security. Here, we solve this serious problem by
showing that the use of Azuma's inequality for parameter estimation makes QKD
with iterative sifting secure again. This means that the existing protocols
whose security proof employs this inequality remain secure even if they employ
iterative sifting. Also, our results highlight a fundamental difference between
the random sampling theorem and Azuma's inequality in proving security.


title: Continuous Top-k Queries over Real-Time Web Streams

abstract:
  The Web has become a large-scale real-time information system forcing us to
revise both how to effectively assess relevance of information for a user and
how to efficiently implement information retrieval and dissemination
functionality. To increase information relevance, Real-time Web applications
such as Twitter and Facebook, extend content and social-graph relevance scores
with "real-time" user generated events (e.g. re-tweets, replies, likes). To
accommodate high arrival rates of information items and user events we explore
a publish/subscribe paradigm in which we index queries and update on the fly
their results each time a new item and relevant events arrive. In this setting,
we need to process continuous top-k text queries combining both static and
dynamic scores. To the best of our knowledge, this is the first work addressing
how non-predictable, dynamic scores can be handled in a continuous top-k query
setting.


title:
Importance sampling for a simple Markovian intensity model using
  subsolutions

abstract:
  This paper considers importance sampling for estimation of rare-event
probabilities in a specific collection of Markovian jump processes used for
e.g. modelling of credit risk. Previous attempts at designing importance
sampling algorithms have resulted in poor performance and the main contribution
of the paper is the design of efficient importance sampling algorithms using
subsolutions. The dynamics of the jump processes causes the corresponding
Hamilton-Jacobi equations to have an intricate state-dependence, which makes
the design of efficient algorithms difficult. We provide theoretical results
that quantify the performance of importance sampling algorithms in general and
construct asymptotically optimal algorithms for some examples. The
computational gain compared to standard Monte Carlo is illustrated by numerical
examples.


title:
On concentration inequalities and their applications for Gibbs measures
  in lattice systems

abstract:
  We consider Gibbs measures on the configuration space $S^{\mathbb{Z}^d}$,
where mostly $d\geq 2$ and $S$ is a finite set. We start by a short review on
concentration inequalities for Gibbs measures. In the Dobrushin uniqueness
regime, we have a Gaussian concentration bound, whereas in the Ising model (and
related models) at sufficiently low temperature, we control all moments and
have a stretched-exponential concentration bound. We then give several
applications of these inequalities whereby we obtain various new results.
Amongst these applications, we get bounds on the speed of convergence of the
empirical measure in the sense of Kantorovich distance, fluctuation bounds in
the Shannon-McMillan-Breiman theorem, fluctuation bounds for the first
occurrence of a pattern, as well as almost-sure central limit theorems.


title: On the Conjugacy Problem in Certain Metabelian Groups

abstract:
  Weanalyzethecomputationalcomplexityofanalgorithmtosolve the conjugacy search
problem in a certain family of metabelian groups. We prove that in general the
time complexity of the conjugacy search problem for these groups is at most
exponential. For a subfamily of groups we prove that the conjugacy search
problem is polynomial. We also show that for a different subfamily the
conjugacy search problem reduces to the discrete logarithm problem.


title: Asymptotic Density and the Theory of Computability: A partial survey

abstract:
  In this article we survey the development of generic and coarse computability
and the main results on how classical asymptotic density interacts with the
theory of computability.


title:
Electric polarization induced by phase separation in magnetically
  ordered and paramagnetic states of RMn2O5 (R=Gd, Bi)

abstract:
  The electric polarization hysteresis loops and remanent polarization were
revealed in multiferroics RMn$_2$O$_5$ with $R = Gd$ and $Bi$ at wide
temperature interval from 5 K up to 330 K. Until recently, the long-range
ferroelectric order having an exchange-striction magnetic nature had been
observed in RMn$_2$O$_5$ only at low temperatures ($T\leq T_C = 30$ -- 35 K).
We believe that the polarization we observed was caused by the frozen
superparaelectric state which was formed by the restricted polar domains
resulting from phase separation and charge carriers self-organization. At some
sufficiently high temperatures $T\gg T_C$ the frozen superparaelectric state
was destroyed, and the conventional superparaelectric state occurred. This
happened when the potential barriers of the restricted polar domain
reorientations become equal to the kinetic energy of the itinerant electrons
(leakage). The hysteresis loops were measured by the so-called PUND method
which allowed us to correctly subtract the contribution of conductivity from
the measured polarization. The correlations between properties of the phase
separation domains and polarization were revealed and studied. The
high-temperature polarization also had a magnetic nature and was controlled by
the magnetic field because the double exchange between pairs of Mn ions with
different valences (Mn$^{3+}$ and Mn$^{4+}$) in RMn$_2$O$_5$ was the basic
interaction resulting in phase separation.


title:
ASTRO-DF: A Class of Adaptive Sampling Trust-Region Algorithms for
  Derivative-Free Stochastic Optimization

abstract:
  We consider unconstrained optimization problems where only "stochastic"
estimates of the objective function are observable as replicates from a Monte
Carlo oracle. The Monte Carlo oracle is assumed to provide no direct
observations of the function gradient. We present ASTRO-DF --- a class of
derivative-free trust-region algorithms, where a stochastic local interpolation
model is constructed, optimized, and updated iteratively. Function estimation
and model construction within ASTRO-DF is adaptive in the sense that the extent
of Monte Carlo sampling is determined by continuously monitoring and balancing
metrics of sampling error (or variance) and structural error (or model bias)
within ASTRO-DF. Such balancing of errors is designed to ensure that Monte
Carlo effort within ASTRO-DF is sensitive to algorithm trajectory, sampling
more whenever an iterate is inferred to be close to a critical point and less
when far away. We demonstrate the almost-sure convergence of ASTRO-DF's
iterates to a first-order critical point when using linear or quadratic
stochastic interpolation models. The question of using more complicated models,
e.g., regression or stochastic kriging, in combination with adaptive sampling
is worth further investigation and will benefit from the methods of proof
presented here. We speculate that ASTRO-DF's iterates achieve the canonical
Monte Carlo convergence rate, although a proof remains elusive.


title: Synchronization of fluctuating delay-coupled chaotic networks

abstract:
  We study the synchronization of chaotic units connected through time-delayed
fluctuating interactions. We focus on small-world networks of Bernoulli and
Logistic units with a fixed chiral backbone. Comparing the synchronization
properties of static and fluctuating networks, we find that random network
alternations can enhance the synchronizability. Synchronized states appear to
be maximally stable when fluctuations are much faster than the time-delay, even
when the instantaneous state of the network does not allow synchronization.
This enhancing effect disappears for very slow fluctuations. For fluctuation
time scales of the order of the time-delay, a desynchronizing resonance is
reported. Moreover, we observe characteristic oscillations, with a periodicity
related to the coupling delay, as the system approaches or drifts away from the
synchronized state.


title:
Transverse Momentum Dependent Fragmenting Jet Functions with
  Applications to Quarkonium Production

abstract:
  We introduce the transverse momentum dependent fragmenting jet function
(TMDFJF), which appears in factorization theorems for cross sections for jets
with an identified hadron. These are functions of $z$, the hadron's
longitudinal momentum fraction, and transverse momentum,
$\boldsymbol{\mathrm{p}}_{\perp}$, relative to the jet axis. In the framework
of Soft-Collinear Effective Theory (SCET) we derive the TMDFJF from both a
factorized SCET cross section and the TMD fragmentation function defined in the
literature. The TMDFJFs are factorized into distinct collinear and
soft-collinear modes by matching onto SCET$_+$. As TMD calculations contain
rapidity divergences, both the renormalization group (RG) and rapidity
renormalization group (RRG) must be used to provide resummed calculations with
next-to-leading-logarithm prime (NLL') accuracy. We apply our formalism to the
production of $J/\psi$ within jets initiated by gluons. In this case the TMDFJF
can be calculated in terms of NRQCD (Non-relativistic quantum chromodynamics)
fragmentation functions. We find that when the $J/\psi$ carries a significant
fraction of the jet energy, the $p_T$ and $z$ distributions differ for
different NRQCD production mechanisms. Another observable with discriminating
power is the average angle that the $J/\psi$ makes with the jet axis.


title: tCG Torsion Pairs

abstract:
  We investigate conditions for when the $t$-structure of
Happel-Reiten-Smal{\o} associated to a torsion pair is a compactly generated
$t$-structure. The concept of a $t$CG torsion pair is introduced and for any
ring $R$, we prove that $\mathbf{t}=(\mathcal{T},\mathcal{F})$ is a $t$CG
torsion pair in $R\text{-Mod}$ if, and only if, there exists, $\{T_{\lambda}\}$
a set of finitely presented $R$-modules in $\mathcal{T}$, such that
$\mathcal{F}=\bigcap \text{Ker}({\text{Hom}}_{R}(T_{\lambda},?))$. We also show
that every $t$CG torsion pair is of finite type, and show that the reciprocal
is not true. Finally, we give a precise description of the $t$CG torsion pairs
over Noetherian rings and von Neumman regular rings.


title:
Learning variable length units for SMT between related languages via
  Byte Pair Encoding

abstract:
  We explore the use of segments learnt using Byte Pair Encoding (referred to
as BPE units) as basic units for statistical machine translation between
related languages and compare it with orthographic syllables, which are
currently the best performing basic units for this translation task. BPE
identifies the most frequent character sequences as basic units, while
orthographic syllables are linguistically motivated pseudo-syllables. We show
that BPE units modestly outperform orthographic syllables as units of
translation, showing up to 11% increase in BLEU score. While orthographic
syllables can be used only for languages whose writing systems use vowel
representations, BPE is writing system independent and we show that BPE
outperforms other units for non-vowel writing systems too. Our results are
supported by extensive experimentation spanning multiple language families and
writing systems.


title:
Community extraction in multilayer networks with heterogeneous community
  structure

abstract:
  Multilayer networks are a useful way to capture and model multiple, binary or
weighted relationships among a fixed group of objects. While community
detection has proven to be a useful exploratory technique for the analysis of
single-layer networks, the development of community detection methods for
multilayer networks is still in its infancy. We propose and investigate a
procedure, called Multilayer Extraction, that identifies densely connected
vertex-layer sets in multilayer networks. Multilayer Extraction makes use of a
significance based score that quantifies the connectivity of an observed
vertex-layer set through comparison with a fixed degree random graph model.
Multilayer Extraction directly handles networks with heterogeneous layers where
community structure may be different from layer to layer. The procedure can
capture overlapping communities, as well as background vertex-layer pairs that
do not belong to any community. We establish consistency of the vertex-layer
set optimizer of our proposed multilayer score under the multilayer stochastic
block model. We investigate the performance of Multilayer Extraction on three
applications and a test bed of simulations. Our theoretical and numerical
evaluations suggest that Multilayer Extraction is an effective exploratory tool
for analyzing complex multilayer networks. Publicly available R software for
Multilayer Extraction is available at
https://github.com/jdwilson4/MultilayerExtraction.


title: Massless QFT and the Newton-Wigner Operator

abstract:
  In this work, the second-quantized version of the spatial-coordinate
operator, known as the Newton-Wigner-Pryce operator, is explicitly given w.r.t.
the massless scalar field. Moreover, transformations of the conformal group are
calculated on eigenfunctions of this operator in order to investigate the
covariance group w.r.t. probability amplitudes of localizing particles.


title:
Gyroscope precession along unbound equatorial plane orbits around a Kerr
  black hole

abstract:
  The precession of a test gyroscope along unbound equatorial plane geodesic
orbits around a Kerr black hole is analyzed with respect to a static reference
frame whose axes point towards the "fixed stars." The accumulated precession
angle after a complete scattering process is evaluated and compared with the
corresponding change in the orbital angle. Limiting results for the
non-rotating Schwarzschild black hole case are also discussed.


title: Packing curves on surfaces with few intersections

abstract:
  Przytycki has shown that the size $\mathcal{N}_{k}(S)$ of a maximal
collection of simple closed curves that pairwise intersect at most $k$ times on
a topological surface $S$ grows at most as a polynomial in $|\chi(S)|$ of
degree $k^{2}+k+1$. In this paper, we narrow Przytycki's bounds by showing that
$$ \mathcal{N}_{k}(S) =O \left( \frac{ |\chi|^{3k}}{ ( \log |\chi| )^2 }
\right) , $$ In particular, the size of a maximal 1-system grows sub-cubically
in $|\chi(S)|$. The proof uses a circle packing argument of Aougab-Souto and a
bound for the number of curves of length at most $L$ on a hyperbolic surface.
When the genus $g$ is fixed and the number of punctures $n$ grows, we can
improve our estimates using a different argument to give $$ \mathcal{N}_{k}(S)
\leq O(n^{2k+2}) . $$ Using similar techniques, we also obtain the sharp
estimate $\mathcal{N}_{2}(S)=\Theta(n^3)$ when $k=2$ and $g$ is fixed.


title: On the Price of Stability of Undirected Multicast Games

abstract:
  In multicast network design games, a set of agents choose paths from their
source locations to a common sink with the goal of minimizing their individual
costs, where the cost of an edge is divided equally among the agents using it.
Since the work of Anshelevich et al. (FOCS 2004) that introduced network design
games, the main open problem in this field has been the price of stability
(PoS) of multicast games. For the special case of broadcast games (every vertex
is a terminal, i.e., has an agent), a series of works has culminated in a
constant upper bound on the PoS (Bilo` et al., FOCS 2013). However, no
significantly sub-logarithmic bound is known for multicast games. In this
paper, we make progress toward resolving this question by showing a constant
upper bound on the PoS of multicast games for quasi-bipartite graphs. These are
graphs where all edges are between two terminals (as in broadcast games) or
between a terminal and a nonterminal, but there is no edge between
nonterminals. This represents a natural class of intermediate generality
between broadcast and multicast games. In addition to the result itself, our
techniques overcome some of the fundamental difficulties of analyzing the PoS
of general multicast games, and are a promising step toward resolving this
major open problem.


title: Perfect and semiperfect restricted enveloping algebras

abstract:
  For a restricted Lie algebra $L$, the conditions under which its restricted
enveloping algebra $u(L)$ is semiperfect are investigated. Moreover, it is
proved that $u(L)$ is left (or right) perfect if and only if $L$ is
finite-dimensional.


title:
Universality at weak and strong non-Hermiticity beyond the elliptic
  Ginibre ensemble

abstract:
  We consider non-Gaussian extensions of the elliptic Ginibre ensemble of
complex non-Hermitian random matrices by fixing the trace
$\operatorname{Tr}(XX^*)$ of the matrix $X$ with a hard or soft constraint.
These ensembles have correlated matrix entries and non-determinantal joint
densities of the complex eigenvalues. We study global and local bulk statistics
in these ensembles, in particular in the limit of weak non-Hermiticity
introduced by Fyodorov, Khoruzhenko and Sommers. Here, the support of the
limiting measure collapses to the real line. This limit was motivated by
physics applications and interpolates between the celebrated sine and Ginibre
kernel. Our results constitute a first proof of universality of the
interpolating kernel. Furthermore, in the limit of strong non-Hermiticity,
where the support of the limiting measure remains an ellipse, we obtain local
Ginibre statistics in the bulk of the spectrum.


title: New Zealand's size and isolation can stimulate new science

abstract:
  It is conventionally thought that New Zealand's distance from the large,
northern hemisphere centres of learning, and our relatively small population
and wealth, are detrimental to the contribution we can make to the advancement
of scientific knowledge. Here the reverse point of view is argued.