title:
Second variation for L-minimal Legendrian submanifolds in
  pseudo-Sasakian manifolds

abstract:
  In this paper we provide a second variation formula for L-minimal Lagrangian
submanifolds in a pseudo-Sasakian manifold. We apply it to the case of
Lorentzian-Sasakian manifolds and relate the L-stability of L-minimal
Legendrians in a Sasakian M to their L-stability in an associated
Lorentzian-Sasakian structure on M.


title: Planar Legendrian graphs

abstract:
  We prove two results on the classification of trivial Legendrian embeddings
$g: G \rightarrow (S^3,\xi_{std})$ of planar graphs. First, the oriented
Legendrian ribbon $R_g$ and rotation invariant $\text{rot}_g$ are a complete
set of invariants. Second, if $G$ is 3-connected or contains $K_4$ as a minor,
then the unique trivial embedding of $G$ is Legendrian simple.


title:
The Influence of Frequency, Recency and Semantic Context on the Reuse of
  Tags in Social Tagging Systems

abstract:
  In this paper, we study factors that influence tag reuse behavior in social
tagging systems. Our work is guided by the activation equation of the cognitive
model ACT-R, which states that the usefulness of information in human memory
depends on the three factors usage frequency, recency and semantic context. It
is our aim to shed light on the influence of these factors on tag reuse. In our
experiments, we utilize six datasets from the social tagging systems Flickr,
CiteULike, BibSonomy, Delicious, LastFM and MovieLens, covering a range of
various tagging settings. Our results confirm that frequency, recency and
semantic context positively influence the reuse probability of tags. However,
the extent to which each factor individually influences tag reuse strongly
depends on the type of folksonomy present in a social tagging system. Our work
can serve as guideline for researchers and developers of tag-based recommender
systems when designing algorithms for social tagging environments.


title:
The Potential of the Dwarf Galaxy Triangulum II for Dark Matter Indirect
  Detection

abstract:
  The recently discovered object Triangulum II appears to be an ultra faint
dwarf spheroidal galaxy which may be one of the most dark matter dominated
objects yet known. In this work we try to estimate the potential of this object
for studies of the indirect detection of self-annihilating dark matter by
obtaining its astrophysical J-factor. We perform a basic estimate of the
velocity gradient to look for signs of the halo being tidally disrupted but
show that the observed value is statistically compatible with zero velocity
gradient. We solve the spherical Jeans equation using Markov Chain Monte Carlo
(MCMC) engine GreAT and the Jeans analysis part of the CLUMPY package. We find
the results point towards a very large J-factor, appearing to make Triangulum
II one of the best targets in the search for dark matter. However we stress
that the very small number of line of sight velocities currently available for
this object make follow up studies essential.


title:
Non-BPS exact solutions and their relation to bions in ${\mathbb
  C}P^{N-1}$ models

abstract:
  We investigate non-BPS exact solutions in ${\mathbb C}P^{N-1}$ sigma models
on ${\mathbb R}^1 \times S^{1}$ with twisted boundary conditions, by using the
Din-Zakrzewski projection method. We focus on the relation of the non-BPS
solutions to the ansatz of multi-instanton (bion) configurations and discuss
their significance in the context of the resurgence theory. We find that the
transition between seemingly distinct configurations of multi-instantons occur
as moduli changes in the non-BPS solutions, and the simplest non-BPS exact
solution corresponds to multi-bion configurations with fully-compressed double
fractional instantons in the middle. It indicates that the non-BPS solutions
make small but nonzero contribution to the resurgent trans-series as special
cases of the multi-bion configurations. We observe a generic pattern of
transitions between distinct multi-bion configurations (flipping partners),
leading to the three essential properties of the non-BPS exact solution: (i)
opposite sign for terms corresponding to the left and right infinities, (ii)
symmetric location of fractional instantons, and (iii) the transition between
distinct bion configurations. By studying the balance of forces, we show that
the relative phases between the instanton constituents play decisive roles in
stability and instability of the muli-instanton configurations. We discuss
local and global instabilities of the solutions such as negative modes and the
flow to the other saddle points, by considering the deformations of the non-BPS
exact solutions within our multi-instanton ansatz. We also briefly discuss some
classes of the non-BPS exact solutions in Grassmann sigma models.


title: Transition to turbulence in wall-bounded flows: Where do we stand?

abstract:
  In this essay, we recall the specificities of the transition to turbulence in
wall-bounded flows and present recent achievements in the understanding of this
problem. The transition is abrupt with laminar-turbulent coexistence over a
finite range of Reynolds numbers, the transitional range. The archetypical
cases of Poiseuille pipe flow and plane Couette flow are first reviewed at the
phenomenological level, together with a few other flow configurations.
Theoretical approaches are then examined with particular emphasis on the
existence of special nontrivial solutions to the Navier-Stokes equations at
finite distance from laminar flow. Dynamical systems theory is most appropriate
to analyze their role, in particular with respect to the transient character of
turbulence in the lower transitional range. The extensions needed to deal with
the prominent spatiotemporal features of the transition are then discussed.
Turbulence growth/decay in terms of statistical physics of many-body systems
and the relevance of directed percolation as a stochastic process able to
account for it are next scrutinized. To conclude, we advocate the recourse to
well-designed modeling able to provide us with a conceptually coherent picture
of the full transitional range and put forward some open issues.


title: A matlab toolbox for continuous state transition algorithm

abstract:
  State transition algorithm (STA) has been emerging as a novel stochastic
method for global optimization in recent few years. To make better
understanding of continuous STA, a matlab toolbox for continuous STA has been
developed. Firstly, the basic principles of continuous STA are briefly
described. Then, a matlab implementation of the standard continuous STA is
explained, with several instances given to show how to use to the matlab
toolbox to minimize an optimization problem with bound constraints. In the same
while, a link is provided to download the matlab toolbox via available
resources.


title: Homological connectivity of random hypergraphs

abstract:
  We consider simplicial complexes that are generated from the binomial random
3-uniform hypergraph by taking the downward-closure. We determine when this
simplicial complex is homologically connected, meaning that its zero-th and
first homology groups with coefficients in $\mathbb{F}_2$ vanish. Although this
is not intrinsically a monotone property, we show that it nevertheless has a
single sharp threshold, and indeed prove a hitting time result relating the
connectedness to the disappearance of the last minimal obstruction.


title:
Topological semimetals protected by off-centered symmetries in
  nonsymmorphic crystals

abstract:
  Topological semimetals have energy bands near the Fermi energy sticking
together at isolated points/lines/planes in the momentum space, which are often
accompanied by stable surface states and intriguing bulk topological responses.
Although it has been known that certain crystalline symmetries play an
important role in protecting band degeneracy, a general recipe for stabilizing
the degeneracy, especially in the presence of spin-orbit coupling, is still
lacking. Here we show that a class of novel topological semimetals with
point/line nodes can emerge in the presence of an off-centered rotation/mirror
symmetry whose symmetry line/plane is displaced from the center of other
symmorphic symmetries in nonsymmorphic crystals. Due to the partial translation
perpendicular to the rotation axis/mirror plane, an off-centered
rotation/mirror symmetry always forces two energy bands to stick together and
form a doublet pair in the relevant invariant line/plane in momentum space.
Such a doublet pair provides a basic building block for emerging topological
semimetals with point/line nodes in systems with strong spin-orbit coupling.


title: All-optical modulation in wavelength-sized epsilon-near-zero media

abstract:
  We investigate the interaction of two pulses (pump and probe) scattered by a
nonlinear epsilon-near-zero (ENZ) slab whose thickness is comparable with the
ENZ wavelength. We show that when the probe has a narrow spectrum localized
around the ENZ wavelength its transmission is dramatically affected by the
intensity of the pump. Conversely, if the probe is not in the ENZ regime, its
propagation is not noticeably affected by the pump. Such all-optical modulation
is due to the oversensitive character of the ENZ regime and it is so efficient
to even occur in a wavelength thick slab.


title:
Sparse Fourier Transform in Any Constant Dimension with Nearly-Optimal
  Sample Complexity in Sublinear Time

abstract:
  We consider the problem of computing a $k$-sparse approximation to the
Fourier transform of a length $N$ signal. Our main result is a randomized
algorithm for computing such an approximation (i.e. achieving the
$\ell_2/\ell_2$ sparse recovery guarantees using Fourier measurements) using
$O_d(k\log N\log\log N)$ samples of the signal in time domain that runs in time
$O_d(k\log^{d+3} N)$, where $d\geq 1$ is the dimensionality of the Fourier
transform. The sample complexity matches the lower bound of $\Omega(k\log
(N/k))$ for non-adaptive algorithms due to \cite{DIPW} for any $k\leq
N^{1-\delta}$ for a constant $\delta>0$ up to an $O(\log\log N)$ factor. Prior
to our work a result with comparable sample complexity $k\log N \log^{O(1)}\log
N$ and sublinear runtime was known for the Fourier transform on the line
\cite{IKP}, but for any dimension $d\geq 2$ previously known techniques either
suffered from a polylogarithmic factor loss in sample complexity or required
$\Omega(N)$ runtime.


title: Coupling single emitters to quantum plasmonic circuits

abstract:
  In recent years the controlled coupling of single photon emitters to
propagating surface plasmons has been intensely studied, which is fueled by the
prospect of a giant photonic non-linearity on a nano-scaled platform. In this
article we will review the recent progress on coupling single emitters to
nano-wires towards the construction of a new platform for strong light-matter
interaction. The control over such a platform might open new doors for quantum
information processing and quantum sensing at the nanoscale, and for the study
of fundamental physics in the ultra-strong coupling regime.


title: A new algebraic structure in the standard model of particle physics

abstract:
  We introduce a new formulation of the real-spectral-triple formalism in
non-commutative geometry (NCG): we explain its mathematical advantages and its
success in capturing the structure of the standard model of particle physics.
The idea, in brief, is to represent $A$ (the algebra of differential forms on
some possibly-noncommutative space) on $H$ (the Hilbert space of spinors on
that space), and to reinterpret this representation as a simple super-algebra
$B=A\oplus H$ with even part $A$ and odd part $H$. $B$ is the fundamental
object in our approach: we show that (nearly) all of the basic axioms and
assumptions of the traditional real-spectral-triple formalism of NCG are
elegantly recovered from the simple requirement that $B$ should be a
differential graded $\ast$-algebra (or "$\ast$-DGA"). Moreover, this
requirement also yields other, new, geometrical constraints. When we apply our
formalism to the NCG traditionally used to describe the standard model of
particle physics, we find that these new constraints are physically meaningful
and phenomenologically correct. In particular, these new constraints provide a
novel interpretation of electroweak symmetry breaking that is geometric rather
than dynamical. This formalism is more restrictive than effective field theory,
and so explains more about the observed structure of the standard model, and
offers more guidance about physics beyond the standard model.


title: Chain development of metric compacts

abstract:
  Chain distance between points in a metric space is defined as the infimum of
epsilon such that there is an epsilon-chain connecting these points. We call a
mapping of a metric compact into the real line a chain development if it
preserves chain distances. We give a criterium of existence of the chain
development for metric compacts. We prove the diameter of any chain development
of a given compact to be the same iff the compact is countable.


title:
Lifshitz transitions, type-II Dirac and Weyl fermions, event horizon and
  all that

abstract:
  The type-II Weyl and type-II Dirac points emerge in semimetals and also in
relativistic systems. In particular, the type-II Weyl fermions may emerge
behind the event horizon of black holes. In this case the horizon with
Painleve-Gullstrand metric serves as the surface of the Lifshitz transition.
This relativistic analogy allows us to simulate the black hole horizon and
Hawking radiation using the fermionic superfluid with supercritical velocity,
and the Dirac and Weyl semimetals with the interface separating the type-I and
type-II states. The difference between such type of the artificial event
horizon and that which arises in acoustic metric is discussed. At the Lifshitz
transition between type-I and type-II fermions the Dirac lines may also emerge,
which are supported by the combined action of topology and symmetry. The
type-II Weyl and Dirac points also emerge as the intermediate states of the
topological Lifshitz transitions. Different configurations of the Fermi
surfaces, involved in such Lifshitz transition, are discussed. In one case the
type-II Weyl point connects the Fermi pockets, and the Lifshitz transition
corresponds to the transfer of the Berry flux between the Fermi pockets. In the
other case the type-II Weyl point connects the outer and inner Fermi surfaces.
At the Lifshitz transition the Weyl point is released from both Fermi surfaces.
These examples reveal the complexity and universality of topological Lifshitz
transitions, which originate from the ubiquitous interplay of a variety of
topological characters of the momentum-space manifolds. For the interacting
electrons, the Lifshitz transitions may lead to the formation of the
dispersionless (flat) band with zero energy and singular density of states,
which opens the route to room-temperature superconductivity.


title: Interband heating processes in a periodically driven optical lattice

abstract:
  We investigate multi-"photon" interband excitation processes in an optical
lattice that is driven periodically in time by a modulation of the lattice
depth. Assuming the system to be prepared in the lowest band, we compute the
excitation spectrum numerically. Moreover, we estimate the effective coupling
parameters for resonant interband excitation processes analytically, employing
degenerate perturbation theory in Floquet space. We find that below a threshold
driving strength, interband excitations are suppressed exponentially with
respect to the inverse driving frequency. For sufficiently low frequencies,
this leads to a rather sudden onset of interband heating, once the driving
strength reaches the threshold. We argue that this behavior is rather generic
and should also be found in lattice systems that are driven by other forms of
periodic forcing. Our results are relevant for Floquet engineering, where a
lattice system is driven periodically in time in order to endow it with novel
properties like the emergence of a strong artificial magnetic field or a
topological band structure. In this context, interband excitation processes
correspond to detrimental heating.


title: Individual ergodic theorems in noncommutative symmetric spaces

abstract:
  It is known that, for a positive Dunford-Schwartz operator in a
noncommutative $L^p-$space, $1\leq p<\infty$ or, more generally, in a
noncommutative Orlicz space with order continuous norm, the corresponding
ergodic averages converge bilaterally almost uniformly. We show that these
averages converge bilaterally almost uniformly in each noncommutative symmetric
space $E$ such that $\mu_t(x) \to 0$ as $t \to 0$ for every $x \in E$, where
$\mu_t(x)$ is a non-increasing rearrangement of $x$. In particular, these
averages converge bilaterally almost uniformly in all noncommutative symmetric
spaces with order continuous norm.


title: Dense coding with mixed state and steerability

abstract:
  Mixed state can be used in dense coding. We have analyzed here that maximally
entangled mixed states like Werner state is dense codeable for a certain range
of state parameter whereas for some wider range of the state parameter the
state is $`$steerable' but cannot be used in dense coding. For qutrit system we
consider isotropic states and have found similar characteristics, like the
states are $`$steerable' for a range of state parameter but for a sub range of
that steerability range only, the states are dense-codeable.


title:
Leading QCD-induced four-loop contributions to the $\beta$-function of
  the Higgs self-coupling in the SM and vacuum stability

abstract:
  We present analytical results for the leading top-Yukawa and QCD contribution
to the $\beta$-function for the Higgs self-coupling $\lambda$ of the Standard
Model at four-loop level, namely the part $\propto y_t^4 g_s^6$ independently
confirming a result given in [1]. We also give the contribution $\propto y_t^2
g_s^6$ of the anomalous dimension of the Higgs field as well as the terms
$\propto y_t g_s^8$ to the top-Yukawa $\beta$-function which can also be
derived from the anomalous dimension of the top quark mass. We compare the
results with the RG functions of the correlators of two and four scalar
currents in pure QCD and find a new relation between the anomalous dimension
$\gamma_0$ of the QCD vacuum energy and the anomalous dimension $\gamma_m^{SS}$
appearing in the RG equation of the correlator of two scalar currents. Together
with the recently computed top-Yukawa and QCD contributions to $\beta_{g_s}$
[2,3] the $\beta$-functions presented here constitute the leading four-loop
contributions to the evolution of the Higgs self-coupling. A numerical estimate
of these terms at the scale of the top-quark mass is presented as well as an
analysis of the impact on the evolution of $\lambda$ up to the Planck scale and
the vacuum stability problem.


title:
An Improved DOA Estimation Algorithm for Circular and Non-Circular
  Signals with High Resolution

abstract:
  In this paper, an improved direction-of-arrival (DOA) estimation algorithm
for circular and non-circular signals is proposed. Most state-of-the-art
algorithms only deal with the DOA estimation problem for the maximal
non-circularity rated and circular signals. However, common non-circularity
rated signals are not taken into consideration. The proposed algorithm can
estimates not only the maximal non-circularity rated and circular signals, but
also the common non-circularity rated signals. Based on the property of the
non-circularity phase and rate, the incident signals can be divided into three
types as mentioned above, which can be estimated separately. The
interrelationship among these signals can be reduced significantly, which means
the resolution performance among different types of signals is improved.
Simulation results illustrate the effectiveness of the proposed method.


title: Nonlinear phenomena in quantum thermoelectrics and heat

abstract:
  We review recent developments in nonlinear quantum transport through
nanostructures and mesoscopic systems driven by thermal gradients or in
combination with voltage biases. Low-dimensional conductors are excellent
platforms to analyze both the thermoelectric and heat dynamics beyond linear
response because due to their small size a small temperature difference applied
across regions gives rise to large thermal biases. We offer a theoretical
discussion based on the scattering approach to highlight the differences
between the linear and the nonlinear regimes of transport. We discuss recent
experiments on quantum dots and molecular junctions subjected to strong
temperature differences. Theoretical predictions concerning the Kondo effect
and heat rectification proposals are briefly examined. An important issue is
the calculation of thermoelectric efficiencies including nonlinearities. Cross
Seebeck effects and nonlinear spin filtering arise in superconductors and
topological insulators while mixed noises between charge and heat currents are
also considered. Finally, we provide an outlook on the possible future
directions of the field.

categories: cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.stat-mech cond-mat.str-el cond-mat.supr-con


title: On quasi n-absorbing elements of multiplicative lattices

abstract:
  In this study, we introduce the concept of quasi n-absorbing elements of
multiplicative lattices. A proper element q is said to be a quasi n-absorbing
element of L if whenever $a^nb\le q$ implies that either $a^n\le q$ or
$a^{n-1}b\le q$. We investigate properties of this new type of elements and
obtain some relations among prime, 2-absorbing, n-absorbing elements in
multiplicative lattices.


title:
Measurement of the neutral $D$ meson mixing parameters in a
  time-dependent amplitude analysis of the $D^0\to\pi^+\pi^-\pi^0$ decay

abstract:
  We measure the $D^0 - {\bar{D}}^0$ mixing parameters using a time-dependent
amplitude analysis of the decay $D^0\to\pi^+\pi^-\pi^0$. The data were recorded
with the BABAR detector at center-of-mass energies at and near the
$\Upsilon(4S)$ resonance, and correspond to an integrated luminosity of
approximately 468.1 ${\rm fb}^{-1}$. The neutral $D$ meson candidates are
selected from $D^{*}(2010)^+\to D^0 \pi_s^+$ decays where the flavor at the
production is identified by the charge of the low momentum pion, $\pi_s^+$. The
measured mixing parameters are $x = (1.5\pm1.2\pm0.6) \%$ and $y =
(0.2\pm0.9\pm0.5) \%$, where the quoted uncertainties are statistical and
systematic, respectively.


title: Unique expansions and intersections of Cantor sets

abstract:
  To each $\alpha\in(1/3,1/2)$ we associate the Cantor set
$$\Gamma_{\alpha}:=\Big\{\sum_{i=1}^{\infty}\epsilon_{i}\alpha^i:
\epsilon_i\in\{0,1\},\,i\geq 1\Big\}.$$
  In this paper we consider the intersection $\Gamma_\alpha \cap (\Gamma_\alpha
+ t)$ for any translation $t\in\mathbb{R}$. We pay special attention to those
$t$ with a unique
  $\{-1,0,1\}$ $\alpha$-expansion, and study the set
  $$D_\alpha:=\{\dim_H(\Gamma_\alpha \cap (\Gamma_\alpha + t)):t \textrm{ has a
unique }\{-1,0,1\}\,\alpha\textrm{-expansion}\}.$$ We prove that there exists a
transcendental number $\alpha_{KL}\approx 0.39433\ldots$ such that: $D_\alpha$
is finite for $\alpha\in(\alpha_{KL},1/2),$ $D_{\alpha_{KL}}$ is infinitely
countable, and $D_{\alpha}$ contains an interval for
$\alpha\in(1/3,\alpha_{KL}).$ We also prove that $D_\alpha$ equals
$[0,\frac{\log 2}{-\log \alpha}]$ if and only if $\alpha\in (1/3,\frac
{3-\sqrt{5}}{2}].$
  As a consequence of our investigation we prove some results on the possible
values of $\dim_{H}(\Gamma_\alpha \cap (\Gamma_\alpha + t))$ when
$\Gamma_\alpha \cap (\Gamma_\alpha + t)$ is a self-similar set. We also give
examples of $t$ with a continuum of $\{-1,0,1\}$ $\alpha$-expansions for which
we can explicitly calculate $\dim_{H}(\Gamma_\alpha\cap(\Gamma_\alpha+t)),$ and
for which $\Gamma_\alpha\cap (\Gamma_\alpha+t)$ is a self-similar set. We also
construct $\alpha$ and $t$ for which $\Gamma_\alpha \cap (\Gamma_\alpha + t)$
contains only transcendental numbers.
  Our approach makes use of digit frequency arguments and a lexicographic
characterisation of those $t$ with a unique $\{-1,0,1\}$ $\alpha$-expansion.


title:
High Contrast Imaging with Spitzer : Constraining the Frequency of Giant
  Planets out to 1000 AU separations

abstract:
  We report results of a re-analysis of archival Spitzer IRAC direct imaging
surveys encompassing a variety of nearby stars. Our sample is generated from
the combined observations of 73 young stars (median age, distance, spectral
type = 85 Myr, 23.3 pc, G5) and 48 known exoplanet host stars with
unconstrained ages (median distance, spectral type = 22.6 pc, G5). While the
small size of Spitzer provides a lower resolution than 8m-class AO-assisted
ground based telescopes, which have been used for constraining the frequency of
0.5 - 13 $M_J$ planets at separations of $10 - 10^2$ AU, its exquisite infrared
sensitivity provides the ability to place unmatched constraints on the
planetary populations at wider separations. Here we apply sophisticated
high-contrast techniques to our sample in order to remove the stellar PSF and
open up sensitivity to planetary mass companions down to 5\arcsec\ separations.
This enables sensitivity to 0.5 - 13 $M_J$ planets at physical separations on
the order of $10^2 - 10^3$ AU , allowing us to probe a parameter space which
has not previously been systematically explored to any similar degree of
sensitivity. Based on a colour and proper motion analysis we do not record any
planetary detections. Exploiting this enhanced survey sensitivity, employing
Monte Carlo simulations with a Bayesian approach, and assuming a mass
distribution of $dn/dm \propto m^{-1.31}$, we constrain (at 95% confidence) a
population of 0.5 - 13 $M_J$ planets at separations of 100 - 1000 AU with an
upper frequency limit of 9%.


title: Bayesian Computing with INLA: A Review

abstract:
  The key operation in Bayesian inference, is to compute high-dimensional
integrals. An old approximate technique is the Laplace method or approximation,
which dates back to Pierre- Simon Laplace (1774). This simple idea approximates
the integrand with a second order Taylor expansion around the mode and computes
the integral analytically. By developing a nested version of this classical
idea, combined with modern numerical techniques for sparse matrices, we obtain
the approach of Integrated Nested Laplace Approximations (INLA) to do
approximate Bayesian inference for latent Gaussian models (LGMs). LGMs
represent an important model-abstraction for Bayesian inference and include a
large proportion of the statistical models used today. In this review, we will
discuss the reasons for the success of the INLA-approach, the R-INLA package,
why it is so accurate, why the approximations are very quick to compute and why
LGMs make such a useful concept for Bayesian computing.


title:
Recurrent Neural Networks for Polyphonic Sound Event Detection in Real
  Life Recordings

abstract:
  In this paper we present an approach to polyphonic sound event detection in
real life recordings based on bi-directional long short term memory (BLSTM)
recurrent neural networks (RNNs). A single multilabel BLSTM RNN is trained to
map acoustic features of a mixture signal consisting of sounds from multiple
classes, to binary activity indicators of each event class. Our method is
tested on a large database of real-life recordings, with 61 classes (e.g.
music, car, speech) from 10 different everyday contexts. The proposed method
outperforms previous approaches by a large margin, and the results are further
improved using data augmentation techniques. Overall, our system reports an
average F1-score of 65.5% on 1 second blocks and 64.7% on single frames, a
relative improvement over previous state-of-the-art approach of 6.8% and 15.1%
respectively.


title: Observation of quantum friction in solid 4He

abstract:
  Classical sliding friction is dominated by the slip-stick mechanism, where
contacts between two bodies are alternately formed and sheared as the bodies
move past each other. When the interface between two bodies is perfectly
smooth, classical friction goes to zero, a state called superlubricity. In this
limit, much weaker mechanisms, called quantum friction are predicted. These
mechanisms are based on an exchange of elementary excitations between two
bodies moving relatively to each other. For the friction to be called quantum,
the excitations must arise from the quantum mechanical description of the
bodies. Photons and phonons are such excitations. Friction results from an
irreversible momentum transfer from these excitations to the bodies, affecting
their motion. We measured the friction force between crystallites of solid 4He
moving relative to each other at low temperatures. Our data are in excellent
agreement with the concept of quantum phonon friction.


title:
Stability analysis of Model Predictive Controllers using Mixed Integer
  Linear Programming

abstract:
  It is a well known fact that finite time optimal controllers, such as MPC
does not necessarily result in closed loop stable systems. Within the MPC
community it is common practice to add a final state constraint and/or a final
state penalty in order to obtain guaranteed stability. However, for more
advanced controller structures it can be difficult to show stability using
these techniques. Additionally in some cases the final state constraint set
consists of so many inequalities that the complexity of the MPC problem is too
big for use in certain fast and time critical applications. In this paper we
instead focus on deriving a tool for a-postiori analysis of the closed loop
stability for linear systems controlled with MPC controllers. We formulate an
optimisation problem that gives a sufficient condition for stability of the
closed loop system and we show that the problem can be written as a Mixed
Integer Linear Programming Problem (MILP)


title:
Recurrence and transience of near-critical multivariate growth models:
  criteria and examples

abstract:
  We discuss complementary recurrence and transience criteria for stochastic
processes $(X_n)_{n \ge 0}$ with values in the $d$-dimensional orthant $\mathbb
R^d_+$ fulfilling a non-linear stochastic equation of the form
$X_{n+1}=MX_n+g(X_n)+ \xi_n$ with a primitive matrix $M$ and random noise
$\xi_n$ and obeying a weak Markov property. As examples we discuss bisexual
Galton-Watson processes and multivariate Galton-Watson processes, which both
may be population size dependent.


title:
Phase Transitions in a Bose-Hubbard Model with Cavity-Mediated
  Global-Range Interactions

abstract:
  We study a system with competing short- and global-range interactions in the
framework of the Bose-Hubbard model. Using a mean-field approximation we obtain
the phase diagram of the system and observe four different phases: a
superfluid, a supersolid, a Mott insulator and a charge density wave, where the
transitions between the various phases can be either of first or second order.
We qualitatively support these results using Monte-Carlo simulations. An
analysis of the low-energy excitations shows that the second-order phase
transition from the charge density wave to the supersolid is associated with
the softening of particle- and hole-like excitations which give rise to a
gapless mode and an amplitude Higgs mode in the supersolid phase. This
amplitude Higgs mode is further transformed into a roton mode which softens at
the supersolid to superfluid phase transition.


title: ACM sheaves on the double plane

abstract:
  The goal of this paper is to start a study of aCM and Ulrich sheaves on
non-integral projective varieties. We show that any aCM vector bundle of rank
two on the double plane is a direct sum of line bundles. As a by-product, any
aCM vector bundle of rank two on a sufficiently high dimensional quadric
hypersurface also splits. We consider aCM and Ulrich vector bundles on a
multiple hyperplanes and prove the existence of such bundles that do not split,
if the multiple hyperplane is linearly embedded into a sufficiently high
dimensional projective space. Then we restrict our attention to the double
plane and give a classification of aCM sheaves of rank at most $3/2$ on the
double plane and describe the family of isomorphism classes of them.


title:
Statistics of the stochastically-forced Lorenz attractor by the
  Fokker-Planck equation and cumulant expansions

abstract:
  We investigate the Fokker-Planck description of the equal-time statistics of
the three-dimensional Lorenz-63 attractor with additive white noise. The
invariant measure is found by computing the zero (or null) mode of the linear
Fokker-Planck operator as a problem of sparse linear algebra. Two variants are
studied: A self-adjoint construction of the linear operator, and the
replacement of diffusion with hyperdiffusion. We also access the low-order
statistics of the system by a perturbative expansion in equal-time cumulants.
Comparison is made to statistics obtained by the standard approach of
accumulation via direct numerical simulation. Theoretical and computational
aspects of the Fokker-Planck and cumulant expansion methods are discussed.


title:
Disturbance scaling in bidirectional vehicle platoons with different
  asymmetry in position and velocity coupling

abstract:
  This paper considers a string of vehicles where the local control law uses
the states of the vehicle's immediate predecessor and follower. The coupling
towards the preceding vehicle can be chosen different to the coupling towards
the following vehicle, which is often referred to as an asymmetric
bidirectional string. Further, the asymmetry for the velocity coupling can be
chosen differently to the asymmetry in the position coupling. It is
investigated how the effect of disturbance on the control errors in the string
depends on the string length. It is shown, that in case of symmetric position
coupling and asymmetric velocity coupling, linear scaling can be achieved. For
symmetric interaction in both states, i.e., in symmetric bidirectional strings,
the errors scale quadratically in the number of vehicles. When the coupling in
position is asymmetric, exponential scaling may occur or the system might even
become unstable. The paper thus gives a comprehensive overview of the
achievable performance in linear, asymmetric, bidirectional platoons. The
results reveal that symmetry in the position coupling and asymmetry in velocity
coupling qualitatively improves the performance of the string. Extensive
numerical results illustrate the theoretical findings.


title: Automatic Knowledge Base Evolution by Learning Instances

abstract:
  Knowledge base is the way to store structured and unstructured data
throughout the web. Since the size of the web is increasing rapidly, there are
huge needs to structure the knowledge in a fully automated way. However
fully-automated knowledge-base evolution on the Semantic Web is a major
challenges, although there are many ontology evolution techniques available.
Therefore learning ontology automatically can contribute to the semantic web
society significantly. In this paper, we propose full-automated ontology
learning algorithm to generate refined knowledge base from incomplete knowledge
base and rdf-triples. Our algorithm is data-driven approach which is based on
the property of each instance. Ontology class is being elaborated by
generalizing frequent property of its instances. By using that developed class
information, each instance can find its most relatively matching class. By
repeating these two steps, we achieve fully-automated ontology evolution from
incomplete basic knowledge base.


title: Mixing Time for Some Adjacent Transposition Markov Chains

abstract:
  We prove rapid mixing for certain Markov chains on the set $S_n$ of
permutations on $1,2,\dots,n$ in which adjacent transpositions are made with
probabilities that depend on the items being transposed. Typically, when in
state $\sigma$, a position $i<n$ is chosen uniformly at random, and $\sigma(i)$
and $\sigma(i{+}1)$ are swapped with probability depending on $\sigma(i)$ and
$\sigma(i{+}1)$. The stationary distributions of such chains appear in various
fields of theoretical computer science, and rapid mixing established in the
uniform case.
  Recently, there has been progress in cases with biased stationary
distributions, but there are wide classes of such chains whose mixing time is
unknown. One case of particular interest is what we call the "gladiator chain,"
in which each number $g$ is assigned a "strength" $s_g$ and when $g$ and $g'$
are adjacent and chosen for possible swapping, $g$ comes out on top with
probability $s_g/(s_g + s_{g'})$. We obtain a polynomial-time upper bound on
mixing time when the gladiators fall into only three strength classes.
  A preliminary version of this paper appeared as "Mixing of Permutations by
Biased Transposition" in STACS 2017.


title:
Effects of Tsallis distribution on parametric resonance in chiral phase
  transitions

abstract:
  The parametric resonance was studied in chiral phase transitions when the
momentum distribution is described by a Tsallis distribution. A Tsallis
distribution has two parameters, the temperature $T$ and the entropic index
$q$. The amplification was estimated in two cases: 1) expansionless case and 2)
one dimensional expansion case. In an expansionless case, the temperature $T$
is constant, and the amplified modes as a function of $T$ were calculated for
various $q$. In one dimensional expansion case, the temperature $T$ decreases
as a function of the proper time, and the amplification as a function of the
transverse momentum was calculated for various $q$. In the expansionless case,
the following facts were found: 1) the larger the value $q$ is, the softer the
amplified modes are for the first and second resonance bands, 2) the amplified
mode of the first resonance band decreases and vanishes, as the temperature $T$
increases, and 3) the amplified mode of the second resonance band decreases and
approaches to zero, as the temperature $T$ increases. In one dimensional
expansion case, the following facts were found: 1) the soft mode is amplified,
2) the amplification is extremely strong around the amplified mode of the first
resonance band at $T=0$, and 3) the magnitude of the amplification as a
function of transverse momentum oscillates around the amplified mode of the
first resonance band at $T=0$.


title: Geometrically Tempered Hamiltonian Monte Carlo

abstract:
  Hamiltonian Monte Carlo (HMC) has become routinely used for sampling from
posterior distributions. Its extension Riemann manifold HMC (RMHMC) modifies
the proposal kernel through distortion of local distances by a Riemannian
metric. The performance depends critically on the choice of metric, with the
Fisher information providing the standard choice. In this article, we propose a
new class of metrics aimed at improving HMC's performance on multi-modal target
distributions. We refer to the proposed approach as geometrically tempered HMC
(GTHMC) due to its connection to other tempering methods. We establish a
geometric theory behind RMHMC to motivate GTHMC and characterize its
theoretical properties. Moreover, we develop a novel variable step size
integrator for simulating Hamiltonian dynamics to improve on the usual
St\"{o}rmer-Verlet integrator which suffers from numerical instability in GTHMC
settings. We illustrate GTHMC through simulations, demonstrating generality and
substantial gains over standard HMC implementations in terms of effective
sample sizes.


title: A spin glass approach to the directed feedback vertex set problem

abstract:
  A directed graph (digraph) is formed by vertices and arcs (directed edges)
from one vertex to another. A feedback vertex set (FVS) is a set of vertices
that contains at least one vertex of every directed cycle in this digraph. The
directed feedback vertex set problem aims at constructing a FVS of minimum
cardinality. This is a fundamental cycle-constrained hard combinatorial
optimization problem with wide practical applications. In this paper we
construct a spin glass model for the directed FVS problem by converting the
global cycle constraints into local arc constraints, and study this model
through the replica-symmetric (RS) mean field theory of statistical physics. We
then implement a belief propagation-guided decimation (BPD) algorithm for
single digraph instances. The BPD algorithm slightly outperforms the simulated
annealing algorithm on large random graph instances. The predictions of the RS
mean field theory are noticeably lower than the BPD results, possibly due to
its neglect of cycle-caused long range correlations.


title: H\'enon-Heiles Interaction for Hydrogen Atom in Phase Space

abstract:
  Using elements of symmetry, as gauge invariance, several aspects of a
Schr\"odinger equation represented in phase-space are introduced and analyzed
under physical basis. The Hydrogen atom is explored in the same context. Then
we add a H\'enon-Heiles potential to the Hydrogen atom in order to explore
chaotic features.

categories: quant-ph math-ph math.MP physics.atom-ph


title:
A Modified CSMA/CA Protocol for OFDM Underwater Networks: Cross Layer
  Design

abstract:
  The underwater acoustic channel continues to present significant challenges
to efficient throughput performance of underwater acoustic sensor networks
(UASNs) in varying scenarios. As a result, cross-layer approaches that explore
joint PHY/MAC strategies are worthy of further exploration. We consider a
recent high-speed OFDM modem and propose a new cross-layer solution based on
modified CSMA/CA, for a canonical star network topology with few nodes (the
most common scenario in UASNs). Some innovations to an adaptive OFDM PHY link
are developed to jointly select the modulation, convolutional coding and
frequency diversity order (different transmission modes) for matching varying
channel conditions. Additionally, receiver logic that disambiguates the cause
of packet loss between a) that caused by channel vs. b) that due to collisions
is used to modify the ARQ/backoff logic for retransmissions with CSMA/CA random
access. Simulation results reveal that the cross-layer design can effectively
increase network throughput.


title: Prevailing dust-transport directions on comet 67P/Churyumov-Gerasimenko

abstract:
  Dust transport and deposition behind larger boulders on the comet
67P/Churyumov-Gerasimenko (67P/C-G) have been observed by the Rosetta mission.
We present a mechanism for dust transport vectors based on a homogenous surface
activity model incorporating in detail the topography of 67P/C-G. The
combination of gravitation, gas drag, and Coriolis force leads to specific dust
transfer pathways, which for higher dust velocities fuel the near nucleus coma.
By distributing dust sources homogeneously across the whole cometary surface,
we derive a global dust-transport map of 67P/C-G. The transport vectors are in
agreement with the reported wind-tail directions in the Philae descent area.


title: Origin and Suppression of $1/f$ Magnetic Flux Noise

abstract:
  Magnetic flux noise is a dominant source of dephasing and energy relaxation
in superconducting qubits. The noise power spectral density varies with
frequency as $1/f^\alpha$ with $\alpha \sim 1$ and spans 13 orders of
magnitude. Recent work indicates that the noise is from unpaired magnetic
defects on the surfaces of the superconducting devices. Here, we demonstrate
that adsorbed molecular O$_2$ is the dominant contributor to magnetism in
superconducting thin films. We show that this magnetism can be suppressed by
appropriate surface treatment or improvement in the sample vacuum environment.
We observe a suppression of static spin susceptibility by more than an order of
magnitude and a suppression of $1/f$ magnetic flux noise power spectral density
by more than a factor of 5. These advances open the door to realization of
superconducting qubits with improved quantum coherence.


title:
Size distribution of particles in Saturn's rings, missed moonlets and
  misinterpretation of Chariklo rings

abstract:
  Brilliantov et al. (PNAS, 2015) propose a model for the size distribution
~R^-3 for small particles with radius R and ~exp(-(R/Rc)^3) for large
particles, where Rc=5.5 m. In 1989 Longaretti found analytically ~R^-3 for
small particles and R^-6 for large ones (2). The law R^-6 also describes
moonlets with size ~ 0.1-1 km. Cut-off law from Brilliantov et al. model does
not describe moonlets and requires new mechanism for the origin of ~ 1 km size
bodies. This model does not take into account the key effects of
self-gravitation of large particles and differential rotation of the rings.
Longaretti used a more accurate model of destruction of particles: "A relative
increase of the erosion/destruction rate of the large particles must take
place, because these particles have relative velocities of collision larger
than the dispersion velocity, due to the differential Keplerian motion". The
new model does not explain the difference between the rings and the satellites
and the authors suggest that their calculations are applicable to the rings of
the Chariklo and Chiron. In fact, the Chariklo rings are not examples of
planetary rings, but proto-satellite disks. Simplified physical model that does
not describe moonlets and the outer boundary of the rings makes the new model
not a step forward but a step backwards in comparison with the papers of 20-30
years old.


title:
Supersimplicity and countable reducts of a unidimensional hypersimple
  theory

abstract:
  We show that a hypersimple unidimensional theory that has a club of reducts,
in the partial order of all countable reducts, that are coordinatized in finite
rank, is supersimple.


title: Enrichment and representability for triangulated categories

abstract:
  Given a fixed tensor triangulated category S we consider triangulated
categories T together with an S-enrichment which is compatible with the
triangulated structure of T. It is shown that, in this setting, an enriched
analogue of Brown representability holds when both S and T are compactly
generated. A natural class of examples of such enriched triangulated categories
categories are module categories over separable monoids in S. In this context
we prove a version of the Eilenberg-Watts theorem for exact coproduct and
copower preserving S-functors, i.e., we show that any such functor between the
module categories of separable monoids in S is given by tensoring with a
bimodule.


title:
An improvement of the product integration method for a weakly singular
  Hammerstein equation

abstract:
  We present a new method to solve nonlinear Hammerstein equations with weakly
singular kernels. The process to approximate the solution, followed usually,
consists in adapting the discretization scheme from the linear case in order to
obtain a nonlinear system in a finite dimensional space and solve it by any
linearization method. In this paper, we propose to first linearize, via Newton
method, the nonlinear operator equation and only then to discretize the
obtained linear equations by the product integration method. We prove that the
iterates, issued from our method, tends to the exact solution of the nonlinear
Hammerstein equation when the number of Newton iterations tends to infinity,
whatever the discretization parameter can be. This is not the case when the
discretization is done first: in this case, the accuracy of the approximation
is limited by the mesh size discretization. A Numerical example is given to
confirm the theorical result.


title: Relative motion and rest frames on de Sitter spacetimes

abstract:
  The Nachtmann boosting method is completed with gauge transformations in
order to be applied to the study of the relative geodesic motion on the de
Sitter spacetimes, finding how the conserved quantities transform under
isometries and defining the rest frames of massive mobiles.


title:
A reconstruction algorithm based on topological gradient for an inverse
  problem related to a semilinear elliptic boundary value problem

abstract:
  In this paper we develop a reconstruction algorithm for the solution of an
inverse boundary value problem dealing with a semilinear elliptic partial
differential equation of interest in cardiac electrophysiology. The goal is the
detection of small inhomogeneities located inside a domain $\Omega$, where the
coefficients of the equation are altered, starting from observations of the
solution of the equation on the boundary $\partial \Omega$. Exploiting
theoretical results recently achieved in [11], we implement a reconstruction
procedure based on the computation of the topological gradient of a suitable
cost functional. Numerical results obtained for several test cases finally
assess the feasibility and the accuracy of the proposed technique.


title: AKARI/IRC Near-Infrared Spectral Atlas of Galactic Planetary Nebulae

abstract:
  Near-infrared (2.5-5.0$\,\mu$m) low-resolution
($\lambda/\Delta\lambda{\sim}100$) spectra of 72 Galactic planetary nebulae
(PNe) were obtained with the Infrared Camera (IRC) in the post-helium phase.
The IRC, equipped with a $1'{\times}1'$ window for spectroscopy of a point
source, was capable of obtaining near-infrared spectra in a slit-less mode
without any flux loss due to a slit. The spectra show emission features
including hydrogen recombination lines and the 3.3-3.5$\,\mu$m hydrocarbon
features. The intensity and equivalent width of the emission features were
measured by spectral fitting. We made a catalog providing unique information on
the investigation of the near-infrared emission of PNe. In this paper, details
of the observations and characteristics of the catalog are described.


title:
Diphoton signal via Chern-Simons interaction in a warped geometry
  scenario

abstract:
  The Kalb-Ramond field, identifiable with bulk torsion in a five-dimensional
Randall Sundrum (RS) scenario, has Chern-Simons interactions with gauge bosons,
from the requirement of gauge anomaly cancellation. Its lowest Kaluza Klein
(KK) mode on the visible 3-brane can be identified with a spin-0 CP-odd field,
namely, the axion. By virtue of the warped geometry and Chern-Simons couplings,
this axion has unsuppressed interactions with gauge bosons in contrast to
ultra-suppressed interactions with fermions. The ensuing dynamics can lead to a
peak in the diphoton spectrum, which could be observed at the LHC, subject to
the prominence of the signal. Moreover, the results can be numerically
justified when the warp factor is precisely in the range required for
stabilization of the electroweak scale.


title: Sound Speed and Viscosity of Semi-Relativistic Relic Neutrinos

abstract:
  Generalized fluid equations, using sound speed $c_{\rm eff}^2$ and viscosity
$c_{\rm vis}^2$ as effective parameters, provide a convenient phenomenological
formalism for testing the relic neutrino "null hypothesis," i.e. that that
neutrinos are relativistic and free-streaming prior to recombination. In this
work, we relax the relativistic assumption and ask "to what extent can the
generalized fluid equations accommodate finite neutrino mass?" We consider both
the mass of active neutrinos, which are largely still relativistic at
recombination $m^2 / T^2 \sim 0.2$, and the effect of a semi-relativistic
sterile component. While there is no one-to-one mapping between mass/mixing
parameters and $c_{\rm eff}^2$ and $c_{\rm vis}^2$, we demonstrate that the
existence of a neutrino mass could induce a bias to measurements of $c_{\rm
eff}^2$ and $c_{\rm vis}^2$ at the level of $0.01 m^2 / T^2 \sim 10^{-3}$.


title: The duration distribution of Swift Gamma-Ray Bursts

abstract:
  Decades ago two classes of gamma-ray bursts were identified and delineated as
having durations shorter and longer than about 2 s. Subsequently indications
also supported the existence of a third class. Using maximum likelihood
estimation we analyze the duration distribution of 888 Swift BAT bursts
observed before October 2015. Fitting three log-normal functions to the
duration distribution of the bursts provides a better fit than two log-normal
distributions, with 99.9999% significance. Similarly to earlier results, we
found that a fourth component is not needed. The relative frequencies of the
distribution of the groups are 8% for short, 35% for intermediate and 57% for
long bursts which correspond to our previous results. We analyse the redshift
distribution for the 269 GRBs of the 888 GRBs with known redshift. We find no
evidence for the previously suggested difference between the long and
intermediate GRBs' redshift distribution. The observed redshift distribution of
the 20 short GRBs differs with high significance from the distributions of the
other groups.


title: Hamilton cycles, minimum degree and bipartite holes

abstract:
  We present a tight extremal threshold for the existence of Hamilton cycles in
graphs with large minimum degree and without a large ``bipartite hole`` (two
disjoint sets of vertices with no edges between them). This result extends
Dirac's classical theorem, and is related to a theorem of Chv\'atal and
Erd\H{o}s.
  In detail, an $(s, t)$-bipartite-hole in a graph $G$ consists of two disjoint
sets of vertices $S$ and $T$ with $|S|= s$ and $|T|=t$ such that there are no
edges between $S$ and $T$; and $\widetilde{\alpha}(G)$ is the maximum integer
$r$ such that $G$ contains an $(s, t)$-bipartite-hole for every pair of
non-negative integers $s$ and $t$ with $s + t = r$. Our central theorem is that
a graph $G$ with at least $3$ vertices is Hamiltonian if its minimum degree is
at least $\widetilde{\alpha}(G)$.
  From the proof we obtain a polynomial time algorithm that either finds a
Hamilton cycle or a large bipartite hole. The theorem also yields a condition
for the existence of $k$ edge-disjoint Hamilton cycles. We see that for dense
random graphs $G(n,p)$, the probability of failing to contain many
edge-disjoint Hamilton cycles is $(1 - p)^{(1 + o(1))n}$. Finally, we discuss
the complexity of calculating and approximating $\widetilde{\alpha}(G)$.


title: Variable length trajectory compressible hybrid Monte Carlo

abstract:
  Hybrid Monte Carlo (HMC) generates samples from a prescribed probability
distribution in a configuration space by simulating Hamiltonian dynamics,
followed by the Metropolis (-Hastings) acceptance/rejection step. Compressible
HMC (CHMC) generalizes HMC to a situation in which the dynamics is reversible
but not necessarily Hamiltonian. This article presents a framework to further
extend the algorithm. Within the existing framework, each trajectory of the
dynamics must be integrated for the same amount of (random) time to generate a
valid Metropolis proposal. Our generalized acceptance/rejection mechanism
allows a more deliberate choice of the integration time for each trajectory.
The proposed algorithm in particular enables an effective application of
variable step size integrators to HMC-type sampling algorithms based on
reversible dynamics. The potential of our framework is further demonstrated by
another extension of HMC which reduces the wasted computations due to unstable
numerical approximations and corresponding rejected proposals.


title: Random Perfect Graphs

abstract:
  We investigate the asymptotic structure of a random perfect graph $P_n$
sampled uniformly from the perfect graphs on vertex set $\{1,\ldots,n\}$. Our
approach is based on the result of Pr\"omel and Steger that almost all perfect
graphs are generalised split graphs, together with a method to generate such
graphs almost uniformly.
  We show that the distribution of the maximum of the stability number
$\alpha(P_n)$ and clique number $\omega(P_n)$ is close to a concentrated
distribution $L(n)$ which plays an important role in our generation method. We
also prove that the probability that $P_n$ contains any given graph $H$ as an
induced subgraph is asymptotically $0$ or $\frac12$ or $1$. Further we show
that almost all perfect graphs are $2$-clique-colourable, improving a result of
Bacs\'o et al from 2004; they are almost all Hamiltonian; they almost all have
connectivity $\kappa(P_n)$ equal to their minimum degree; they are almost all
in class one (edge-colourable using $\Delta$ colours, where $\Delta$ is the
maximum degree); and a sequence of independently and uniformly sampled perfect
graphs of increasing size converges almost surely to the graphon $W_P(x, y) =
\frac12(\mathbb{1}[x \le 1/2] + \mathbb{1}[y \le 1/2])$.


title:
Particle Content of Quadratic and $f(R_{\mu\nu\sigma \rho})$ Theories in
  $(A)dS$

abstract:
  We perform a complete decoupling of the degrees of freedom of quadratic
gravity and the generic $f (R_{\mu\nu\sigma \rho})$ theory about any one of
their possible vacua, i.e. maximally symmetric solution, find the masses of the
spin-2 and spin-0 modes in explicit forms.


title: Behaviour of entropy under bounded and integrable orbit equivalence

abstract:
  Let $G$ and $H$ be infinite finitely generated amenable groups. This paper
studies two notions of equivalence between actions of such groups on standard
Borel probability spaces. They are defined as stable orbit equivalences in
which the associated cocycles satisfy certain tail bounds. In `integrable
stable orbit equivalence', the length in $H$ of the cocycle-image of an element
of $G$ must have finite integral over its domain (a subset of the $G$-system),
and similarly for the reverse cocycle. In `bounded stable orbit equivalence',
these functions must be essentially bounded in terms of the length in $G$.
`Integrable' stable orbit equivalence arises naturally in the study of
integrable measure equivalence of groups themselves, as introduced recently by
Bader, Furman and Sauer.
  The main result is a formula relating the Kolmogorov--Sinai entropies of two
actions which are equivalent in one of these ways. Under either of these tail
assumptions, the entropies stand in a proportion given by the compression
constant of the stable orbit equivalence. In particular, in the case of full
orbit equivalence subject to such a tail bound, entropy is an invariant. This
contrasts with the case of unrestricted orbit equivalence, under which all free
ergodic actions of countable amenable groups are equivalent. The proof uses an
entropy-bound based on graphings for orbit equivalence relations, and in
particular on a new notion of cost which is weighted by the word lengths of
group elements.


title:
Conformal embeddings of affine vertex algebras in minimal $W$-algebras
  II: decompositions

abstract:
  We present methods for computing the explicit decomposition of the minimal
simple affine $W$-algebra $W_k(\mathfrak g, \theta)$ at a conformal level $k$
as a module for its maximal affine subalgebra $\mathcal V_k(\mathfrak
g^{\natural})$. A particular emphasis is given on the application of affine
fusion rules to the determination of branching rules. In almost all cases when
$\mathfrak g^{\natural}$ is a semisimple Lie algebra, we show that, for a
suitable conformal level $k$, $W_k(\mathfrak g, \theta)$ is isomorphic to an
extension of $\mathcal V_k(\mathfrak g^{\natural})$ by its simple module. We
are able to prove that in certain cases $W_k(\mathfrak g, \theta)$ is a simple
current extension of $\mathcal V_k(\mathfrak g^{\natural})$. In order to
analyze more complicated non simple current extensions at conformal levels, we
present an explicit realization of the simple $W$-algebra $W_{k}(sl(4),
\theta)$ at $k=-8/3$. We prove, as conjectured in arXiv:1407.1527, that
$W_{k}(sl(4), \theta)$ is isomorphic to the vertex algebra $\mathcal R^{(3)}$,
and construct infinitely many singular vectors using screening operators. We
also construct a new family of simple current modules for the vertex algebra
$V_k (sl(n))$ at certain admissible levels and for $V_k (sl(m | n)), m\ne n,
m,n\geq 1$ at arbitrary levels.


title: Allocation Schemes of Ressources with Downgrading

abstract:
  We consider a server with large capacity delivering video files encoded in
various resolutions. We assume that the system is under saturation in the sense
that the total demand exceeds the server capacity $C$. In such a case, requests
may be rejected. For the policies considered in this paper, instead of
rejecting a video request, it is downgraded. When the occupancy of the server
is above some value $C_0{<}C$, the server delivers the video at a minimal bit
rate. The quantity $C_0$ is the bit rate adaptation threshold. For these
policies, request blocking is thus replaced by bit rate adaptation. Under the
assumptions of Poisson request arrivals and exponential service times, we show
that, by rescaling the system, a process associated to the occupancy of the
server converges to some limiting process whose invariant distribution is
computed by a Wiener-Hopf technique. This allows us to derive an asymptotic
expression of the key performance measure of such a policy, the equilibrium
probability that a request is transmitted without downgrading. Numerical
applications of these results are presented.


title: HDRFusion: HDR SLAM using a low-cost auto-exposure RGB-D sensor

abstract:
  We describe a new method for comparing frame appearance in a frame-to-model
3-D mapping and tracking system using an low dynamic range (LDR) RGB-D camera
which is robust to brightness changes caused by auto exposure. It is based on a
normalised radiance measure which is invariant to exposure changes and not only
robustifies the tracking under changing lighting conditions, but also enables
the following exposure compensation perform accurately to allow online building
of high dynamic range (HDR) maps. The latter facilitates the frame-to-model
tracking to minimise drift as well as better capturing light variation within
the scene. Results from experiments with synthetic and real data demonstrate
that the method provides both improved tracking and maps with far greater
dynamic range of luminosity.


title:
An open reproducible framework for the study of the iterated prisoner's
  dilemma

abstract:
  The Axelrod library is an open source Python package that allows for
reproducible game theoretic research into the Iterated Prisoner's Dilemma. This
area of research began in the 1980s but suffers from a lack of documentation
and test code. The goal of the library is to provide such a resource, with
facilities for the design of new strategies and interactions between them, as
well as conducting tournaments and ecological simulations for populations of
strategies.
  With a growing collection of 139 strategies, the library is a also a platform
for an original tournament that, in itself, is of interest to the game
theoretic community. This paper describes the Iterated Prisoner's Dilemma, the
Axelrod library and its development, and insights gained from some novel
research.


title:
On the cusp anomalous dimension in the ladder limit of $\mathcal N=4$
  SYM

abstract:
  We analyze the cusp anomalous dimension in the (leading) ladder limit of
$\mathcal N=4$ SYM and present new results for its higher-order perturbative
expansion. We study two different limits with respect to the cusp angle $\phi$.
The first is the light-like regime where $x = e^{i\,\phi}\to 0$. This limit is
characterised by a non-trivial expansion of the cusp anomaly as a sum of powers
of $\log x$, where the maximum exponent increases with the loop order. The
coefficients of this expansion have remarkable transcendentality features and
can be expressed by products of single zeta values. We show that the whole
logarithmic expansion is fully captured by a solvable Woods-Saxon like
one-dimensional potential. From the exact solution, we extract generating
functions for the cusp anomaly as well as for the various specific
transcendental structures appearing therein. The second limit that we discuss
is the regime of small cusp angle. In this somewhat simpler case, we show how
to organise the quantum mechanical perturbation theory in a novel efficient way
by means of a suitable all-order Ansatz for the ground state of the associated
Schr\"odinger problem. Our perturbative setup allows to systematically derive
higher-order perturbative corrections in powers of the cusp angle as explicit
non-perturbative functions of the effective coupling. This series approximation
is compared with the numerical solution of the Schr\"odinger equation to show
that we can achieve very good accuracy over the whole range of coupling and
cusp angle. Our results have been obtained by relatively simple techniques.
Nevertheless, they provide several non-trivial tests useful to check the
application of Quantum Spectral Curve methods to the ladder approximation at
non zero $\phi$, in the two limits we studied.


title:
Scattering of surface plasmon-polaritons in a graphene multilayer
  photonic crystal with inhomogeneous doping

abstract:
  The propagation of a surface plasmon-polariton along a stack of doped
graphene sheets is considered. This auxiliary problem is used to discuss: (i)
the scattering of such a mode at an interface between the stack and the vacuum;
(ii) the scattering at an interface where there is a sudden change of the
electronic doping. The formalism is then extended to the {\it barrier problem}.
In this system rich physics is found for the plasmonic mode, showing: total
reflection, total transmission, Fabry-P\'erot oscillations, and coupling to
photonic modes.


title:
Thermodynamic implications of the gravitationally induced particle
  creation scenario

abstract:
  A rigorous thermodynamic analysis has been done at the apparent horizon of a
spatially flat Friedmann-Lemaitre-Robertson-Walker universe for the
gravitationally induced particle creation scenario with constant specific
entropy and an arbitrary particle creation rate $\Gamma$. Assuming a perfect
fluid equation of state $p=(\gamma -1)\rho$ with $\frac{2}{3} \leq \gamma \leq
2$, the first law, the generalized second law (GSL), and thermodynamic
equilibrium have been studied and an expression for the total entropy (i.e.,
horizon entropy plus fluid entropy) has been obtained which does not contain
$\Gamma$ explicitly. Moreover, a lower bound for the fluid temperature $T_f$
has also been found which is given by $T_f \geq
8\left(\frac{\frac{3\gamma}{2}-1}{\frac{2}{\gamma}-1}\right)H^2$. It has been
shown that the GSL is satisfied for $\frac{\Gamma}{3H} \leq 1$. Further, when
$\Gamma$ is constant, thermodynamic equilibrium is always possible for
$\frac{1}{2}<\frac{\Gamma}{3H} < 1$, while for $\frac{\Gamma}{3H} \leq
\text{min}\left\lbrace \frac{1}{2},\frac{2\gamma -2}{3\gamma -2} \right\rbrace$
and $\frac{\Gamma}{3H} \geq 1$, equilibrium can never be attained.
Thermodynamic arguments also lead us to believe that during the radiation
phase, $\Gamma \leq H$. When $\Gamma$ is not a constant, thermodynamic
equilibrium holds if $\ddot{H} \geq \frac{27}{4}\gamma ^2 H^3
\left(1-\frac{\Gamma}{3H}\right)^2$, however, such a condition is by no means
necessary for the attainment of equilibrium.


title: Shallow-band superconductors: pushing superconductivity types apart

abstract:
  Magnetic response is a fundamental property of superconducting materials,
which helps to distinguish two superconductivity types: the ideally diamagnetic
type I and type II, which can develop the mixed state with Abrikosov vortices.
We demonstrate that multi-band superconductors with one shallow band, that have
recently attracted much attention for their high critical temperatures and
unusual properties, often stay apart of this simple classification. In a wide
range of microscopic parameters such systems fall into the inter-type or
transitional interval in between the standard types and display unconventional
mixed state configurations.


title:
Variability of GeV gamma-ray emission in QSO B0218+357 due to
  microlensing on intermediate size structures

abstract:
  Strong gravitational lensing leads to an occurrence of multiple images, with
different magnifications, of a lensed source. Those magnifications can in turn
be modified by microlensing on smaller mass scales within the lens. Recently,
measurements of the changes in the magnification ratio of the individual images
have been proposed as a powerful tool for estimation of the size and velocity
of the emission region in the lensed source. The changes of the magnification
ratios in blazars PKS1830-211 and QSO B0218+357, if interpreted as caused by a
microlensing on individual stars, put strong constraints on those two
variables. These constraints are difficult to accommodate with the current
models of gamma-ray emission in blazars. In this paper we study if similar
changes in the magnification ratio can be caused by microlensing on
intermediate size structures in the lensing galaxy. We investigate in details
three classes of possible lenses: globular clusters (GC), open clusters (OC)
and giant molecular clouds (GMC). We apply this scenario to the case of QSO
B0218+357. Our numerical simulations show that changes in magnifi- cations with
similar time scales can be obtained for relativistically moving emission
regions with sizes up to 0.01 pc in the case of microlensing on the cores of
GCs or clumps in GMCs. From the density of such structures in spiral galaxies
we estimate however that lensing in giant molecular clouds would be more
common.


title: Some operators on interval-valued Hesitant fuzzy soft sets

abstract:
  The main aim of this paper is to introduced the operations "Union" and
"Intersection," and four operators $O_1, O_2, O_3, O_4 $ on interval-valued
hesitant fuzzy soft sets and discuss some of their properties.


title: Staged Models for Interdisciplinary Research

abstract:
  Modellers of complex biological or social systems are often faced with an
invidious choice: to use simple models with few mechanisms that can be fully
analysed, or to construct complicated models that include all the features
which are thought relevant. The former ensures rigour, the latter relevance. We
discuss a method that combines these two approaches, beginning with a complex
model and then modelling the complicated model with simpler models. The
resulting "chain" of models ensures some rigour and relevance. We illustrate
this process on a complex model of voting intentions, constructing a reduced
model which agrees well with the predictions of the full model. Experiments
with variations of the simpler model yield additional insights which are hidden
by the complexity of the full model. This approach facilitated collaboration
between social scientists and physicists -- the complex model was specified
based on the social science literature, and the simpler model constrained to
agree (in core aspects) with the complicated model.


title: Recent developments in string model-building and cosmology

abstract:
  In this talk I discuss recent developments in moduli stabilisation, SUSY
breaking and chiral D-brane models together with several interesting features
of cosmological models built in the framework of type IIB string
compactifications. I show that a non-trivial pre-inflationary dynamics can give
rise to a power loss at large angular scales for which there have been mounting
observational hints from both WMAP and Planck. I then describe different
stringy embeddings of inflationary models which yield large or small tensor
modes. I finally argue that reheating is generically driven by the decay of the
lightest modulus which can produce, together with Standard Model particles,
also non-thermal dark matter and light hidden sector degrees of freedom that
behave as dark radiation.


title: Polarity and Monopolarity of $3$-colourable comparability graphs

abstract:
  We sharpen the result that polarity and monopolarity are NP-complete problems
by showing that they remain NP-complete if the input graph is restricted to be
a $3$-colourable comparability graph. We start by presenting a construction
reducing $1$-$3$-SAT to monopolarity of $3$-colourable comparability graphs.
Then we show that polarity is at least as hard as monopolarity for input graphs
restricted to a fixed disjoint-union-closed class. We conclude the paper by
stating that both polarity and monopolarity of $3$-colourable comparability
graphs are NP-complete problems.


title: Detecting Engagement in Egocentric Video

abstract:
  In a wearable camera video, we see what the camera wearer sees. While this
makes it easy to know roughly what he chose to look at, it does not immediately
reveal when he was engaged with the environment. Specifically, at what moments
did his focus linger, as he paused to gather more information about something
he saw? Knowing this answer would benefit various applications in video
summarization and augmented reality, yet prior work focuses solely on the
"what" question (estimating saliency, gaze) without considering the "when"
(engagement). We propose a learning-based approach that uses long-term
egomotion cues to detect engagement, specifically in browsing scenarios where
one frequently takes in new visual information (e.g., shopping, touring). We
introduce a large, richly annotated dataset for ego-engagement that is the
first of its kind. Our approach outperforms a wide array of existing methods.
We show engagement can be detected well independent of both scene appearance
and the camera wearer's identity.


title: A new approach to bounds on mixing

abstract:
  We consider mixing by incompressible flows. In 2003, Bressan stated a
conjecture concerning a bound on the mixing achieved by the flow in terms of an
$L^1$ norm of the velocity field. Existing results in the literature use an
$L^p$ norm with $p>1$. In this paper we introduce a new approach to prove such
results. It recovers most of the existing results and offers new perpective on
the problem. Our approach makes use of a recent harmonic analysis estimate from
Seeger, Smart and Street.


title:
Volumes in the Uniform Infinite Planar Triangulation: from skeletons to
  generating functions

abstract:
  We develop a method to compute the generating function of the number of
vertices inside certain regions of the Uniform Infinite Planar Triangulation
(UIPT). The computations are mostly combinatorial in flavor and the main tool
is the decomposition of the UIPT into layers, called the skeleton
decomposition, introduced by Krikun. In particular, we get explicit formulas
for the generating functions of the number of vertices inside hulls (or
completed metric balls) centered around the root, and the number of vertices
inside geodesic slices of these hulls. We also recover known results about the
scaling limit of the volume of hulls previously obtained by Curien and Le Gall
by studying the peeling process of the UIPT.


title:
Scaling analysis of transverse Anderson localization in a disordered
  optical waveguide

abstract:
  The intention of this manuscript is twofold. First, the mode-width
probability density function (PDF) is introduced as a powerful statistical tool
to study and compare the transverse Anderson localization properties of a
disordered one dimensional optical waveguide. Second, by analyzing the scaling
properties of the mode-width PDF with the transverse size of the waveguide, it
is shown that the mode-width PDF gradually converges to a terminal
configuration. Therefore, it may not be necessary to study a real-sized
disordered structure in order to obtain its statistical localization properties
and the same PDF can be obtained for a substantially smaller structure. This
observation is important because it can reduce the often demanding
computational effort that is required to study the statistical properties of
Anderson localization in disordered waveguides. Using the mode-width PDF,
substantial information about the impact of the waveguide parameters on its
localization properties is extracted. This information is generally obscured
when disordered waveguides are analyzed using other techniques such as the beam
propagation method. As an example of the utility of the mode-width PDF, it is
shown that the cladding refractive index can be used to quench the number of
extended modes, hence improving the contrast in image transport properties of
disordered waveguides.


title:
Long range phase coherencein double barrier magnetic tunnel junctions
  with large thick metallic quantum well

abstract:
  Double barrier heterostructures are model systems for the study of electron
tunneling and discrete energy levels in a quantum well (QW). Until now resonant
tunneling phenomena in metallicQW have been observed for limited thicknesses
(1-2 nm) under which electron phase coherence is conserved. In the present
study we show evidence of QW resonance states in Fe QW up to12 nmthick and at
room temperature in fully epitaxial doubleMgAlOxbarrier magnetic tunnel
junctions. The electron phase coherence displayed in this QWis of unprecedented
quality because ofa homogenous interface phase shift due to the small lattice
mismatch at the Fe/MgAlOx interface. The physical understanding of the critical
role of interface strain on QW phase coherence will greatly promote the
development of the spin-dependent quantum resonant tunneling applications.


title:
Optically confined polarized resonance Raman studies in identifying
  crystalline orientation of sub-diffraction limited AlGaN nanostructure

abstract:
  An optical characterization tool of Raman spectroscopy with extremely weak
scattering cross section tool is not popular to analyze scattered signal from a
single nanostructure in the sub-diffraction regime. In this regard, plasmonic
assisted characterization tools are only relevant in spectroscopic studies of
nanoscale object in the sub-diffraction limit. We have reported polarized
resonance Raman spectroscopic (RRS) studies with strong electron-phonon
coupling to understand the crystalline orientation of a single AlGaN nanowire
of diameter about 100 nm. AlGaN nanowire is grown by chemical vapor deposition
technique using the catalyst assisted vapor-liquid-solid process. The results
are compared with the high resolution transmission electron microscopic
analysis. As a matter of fact, optical confinement effect due to the dielectric
contrast of nanowire with respect to that of surrounding media assisted with
electron-phonon coupling of RRS are useful for the spectroscopic analysis in
the sub-diffraction limit of 325 nm (lamda(2N.A.)^(-1)) using an excitation
wavelength (lamda) of 325 nm and near ultraviolet 40X far field objective with
a numerical aperture (N.A.) value of 0.50.


title:
A multivariate nonlinear mixed effects model for longitudinal image
  analysis: Application to amyloid imaging

abstract:
  It is important to characterize the temporal trajectories of disease-related
biomarkers in order to monitor progression and identify potential points of
intervention. This is especially important for neurodegenerative diseases, as
therapeutic intervention is most likely to be effective in the preclinical
disease stages prior to significant neuronal damage. Longitudinal neuroimaging
allows for the measurement of structural, functional, and metabolic integrity
of the brain over time at the level of voxels. However, commonly used
longitudinal analysis approaches, such as linear mixed effects models, do not
account for the fact that individuals enter a study at various disease stages
and progress at different rates, and generally consider each voxelwise measure
independently. We propose a multivariate nonlinear mixed effects model for
estimating the trajectories of voxelwise neuroimaging biomarkers from
longitudinal data that accounts for such differences across individuals. The
method involves the prediction of a progression score for each visit based on a
collective analysis of voxelwise biomarker data within an
expectation-maximization framework that efficiently handles large amounts of
measurements and variable number of visits per individual, and accounts for
spatial correlations among voxels. This score allows individuals with similar
progressions to be aligned and analyzed together, which enables the
construction of a trajectory of brain changes as a function of an underlying
progression or disease stage. Application of our method to studying images of
beta-amyloid deposition, a hallmark of preclinical Alzheimer's disease,
suggests that precuneus is the earliest cortical region to accumulate amyloid.
The proposed method can be applied to other types of longitudinal imaging data,
including metabolism, blood flow, tau, and structural imaging-derived measures.


title:
BLISP: Enhancing Backscatter Radio with Active Radio for Computational
  RFIDs

abstract:
  We demonstrate the world's first hybrid radio platform which combines the
strengths of active radio (long range and robustness to interference) and
Computational RFIDs (low power consumption). We evaluate the Wireless
Identification and Sensing Platform (WISP), an EPC C1G2 standard-based,
Computational RFID backscatter radio, against Bluetooth Low Energy (BLE) and
show (theoretically and experimentally) that WISP in high channel attenuation
conditions is less energy efficient per received byte than BLE. Exploiting this
observation we design a simple switching mechanisms that backs off to BLE when
radio conditions for WISP are unfavorable. By a set of laboratory experiments,
we show that our proposed hybrid active/backscatter radio obtains higher
goodput than WISP and lower energy consumption than BLE as stand-alone
platforms, especially when WISP is in range of an RFID interrogator for the
majority of the time. Simultaneously, our proposed platform is as energy
efficient as BLE when user is mostly out of RFID interrogator range.


title:
Impact of inclination on quasi-periodic oscillations from spiral
  structures

abstract:
  Context. Quasi-periodic oscillations (QPOs) are a common feature of the power
spectrums of X-ray binaries. Currently it is not possible to unambiguously
differentiate the large number of proposed models to explain these phenomena
through existing observations.
  Aims. We investigate the observable predictions of a simple model that
generates flux modulation: a spiral instability rotating in a thin accretion
disk. This model is motivated by the accretion ejection instability (AEI) model
for low- frequency QPOs (LFQPOs). We are particularly interested in the
inclination dependence of the observables that are associated with this model.
  Methods. We develop a simple analytical model of an accretion disk, which
features a spiral instability. The disk is assumed to emit blackbody radiation,
which is ray-traced to a distant observer. We compute pulse profiles and power
spectra as observed from infinity.
  Results. We show that the amplitude of the modulation associated with the
spiral rotation is a strong function of inclination and frequency. The pulse
profile is quasi-sinusoidal only at low inclination (face-on source). As a
consequence, a higher-inclination geometry leads to a stronger and more diverse
harmonic signature in the power spectrum.
  Conclusions. We present how the amplitude depends on the inclination when the
flux modulation comes from a spiral in the disk. We also include new
observables that could potentially differentiate between models, such as the
pulse profile and the harmonic content of the power spectra of high-inclination
sources that exhibit LFQPOs. These might be important observables to explore
with existing and new instruments.


title: Rugged constant-temperature thermal anemometer

abstract:
  Here we report a robust thermal anemometer which can be easily built. It was
conceived to measure outdoor wind speeds, and for airspeed monitoring in wind
tunnels and other indoor uses. It works at a constant, low temperature of
approximately 90$^\circ$C, so that an independent measurement of the air
temperature is required to give a correct speed reading. Despite the size and
high thermal inertia of the probe, the test results show that this anemometer
is capable of measuring turbulent fluctuations up to ~100 Hz in winds of ~14
m/s, which corresponds to a scale similar to the length of the probe.


title: Active resonator reset in the nonlinear dispersive regime of circuit QED

abstract:
  We present two pulse schemes for actively depleting measurement photons from
a readout resonator in the nonlinear dispersive regime of circuit QED. One
method uses digital feedback conditioned on the measurement outcome while the
other is unconditional. In the absence of analytic forms and symmetries to
exploit in this nonlinear regime, the depletion pulses are numerically
optimized using the Powell method. We shorten the photon depletion time by more
than six inverse resonator linewidths compared to passive depletion by waiting.
We quantify the benefit by emulating an ancilla qubit performing repeated
quantum parity checks in a repetition code. Fast depletion increases the mean
number of cycles to a spurious error detection event from order 1 to 75 at a 1
microsecond cycle time.


title: Exoplanets versus brown dwarfs: the CoRoT view and the future

abstract:
  CoRoT has detected by transit several tens of objects whose radii run from
1.67 Earth radius. Their mass run from less than 5.7 Earth mass (CoRoT-24 b,
Alonso et al. 2014) to 63 Jupiter mass (CoRoT-15 b, Bouchy et al. 2011). One
could be tempted to think that more massive the object is, the larger it is in
size and that there is some limit in mass and/or radius beyond which objects
are not planets but very low mass stars below the 80 Jupiter mass limit to
trigger nuclear fusion (namely "brown dwarfs" ). CoRoT findings contribute to
the planet versus brown dwarf debate since there is no clear mass-radius
relation.


title:
Chiral p-wave superconductivity in Sb(111) thin films close to Van Hove
  singularities

abstract:
  We theoretically investigate the development of unconventional
superconductivity in the Sb(111) thin film when its Fermi level is tuned to
near type-II Van Hove singularities (VHS), which locate at non-time-reversal
invariant momenta. Via patch renormalization group analysis, we show that the
leading instability is a chiral p + ip-wave superconducting order. The origin
of such pairing relies on the hexagonal structure of the VHS and strong
spin-orbit coupling, resulting in the anisotropy of the electron-electron
scattering to provide an attractive channel. Our study hence suggests that
superconducting Sb thin films originated from VHS physics may host Majorana
zero modes in the magnetic vortices and provides another application
perspective to such material.


title:
Biomimetic race model of the loop between the superior colliculus and
  the basal ganglia: Subcortical selection of saccade targets

abstract:
  The Superior Colliculus, a laminar structure involved in the retinotopic
mapping of the visual field, plays a cardinal role in the several cortical and
subcortical loops of the saccadic system. Although the selection of saccade
targets has long been thought to be the sole product of cortical processes, a
growing body of evidence hints at the implication of the Superior Colliculus,
firstly by the lateral connections between the neurons of its maps, and
secondly by its interactions with the midbrain Basal Ganglia, already renowned
for their role in decision making. We propose a biomimetic population-coded
race model of selection based on a dynamic tecto-basal loop that reproduces the
observed ability of the Superior Colliculus to stochastically select between
similar stimuli, the accuracy of this selection depending on the
discriminability of the target and the distractors. Our model also offers an
explanation for the phenomenon of Remote Distractor Effect based on the lateral
connectivity within the Basal Ganglia circuitry rather than on lateral
inhibitions within the collicular maps. Finally, we propose a role for the
intermediate layers of the Superior Colliculus, as stochastic integrators
dynamically gated by the selective disinhibition of the Basal Ganglia channels
that is consistent with the recorded activity profiles of these neurons.


title: Integral points and orbits of endomorphisms on the projective plane

abstract:
  We analyze when integral points on the complement of a finite union of curves
in $\mathbb{P}^2$ are potentially dense. We divide the analysis of these affine
surfaces based on their logarithmic Kodaira dimension $\bar{\kappa}$. When
$\bar{\kappa} = -\infty$, we completely characterize the potential density of
integral points in terms of the number of irreducible components on the surface
at infinity and the number of multiple members in a pencil naturally associated
to the surface. When integral points are not potentially dense, we show that
they lie on finitely many effectively computable curves. When $\bar{\kappa} =
0$, we prove that integral points are always potentially dense. The bulk of our
analysis concerns the subtle case of $\bar{\kappa}=1$. We determine the
potential density of integral points in a number of cases and develop tools for
studying integral points on surfaces fibered over a curve. Finally, nondensity
of integral points in the case $\bar{\kappa}=2$ is predicted by the Lang-Vojta
conjecture, to which we have nothing new to add.
  In a related direction, we study integral points in orbits under
endomorphisms of $\mathbb{P}^2$. Assuming the Lang--Vojta conjecture, we prove
that an orbit under an endomorphism $\phi$ of $\mathbb{P}^2$ can contain a
Zariski-dense set of integral points (with respect to some nontrivial effective
divisor) only if there is a nontrivial completely invariant proper
Zariski-closed set with respect to $\phi$. This may be viewed as a
generalization of a result of Silverman on integral points in orbits of
rational functions. We provide many specific examples, and end with some open
problems.


title:
A Review of Theoretical and Practical Challenges of Trusted Autonomy in
  Big Data

abstract:
  Despite the advances made in artificial intelligence, software agents, and
robotics, there is little we see today that we can truly call a fully
autonomous system. We conjecture that the main inhibitor for advancing autonomy
is lack of trust. Trusted autonomy is the scientific and engineering field to
establish the foundations and ground work for developing trusted autonomous
systems (robotics and software agents) that can be used in our daily life, and
can be integrated with humans seamlessly, naturally and efficiently.
  In this paper, we review this literature to reveal opportunities for
researchers and practitioners to work on topics that can create a leap forward
in advancing the field of trusted autonomy. We focus the paper on the `trust'
component as the uniting technology between humans and machines. Our inquiry
into this topic revolves around three sub-topics: (1) reviewing and positioning
the trust modelling literature for the purpose of trusted autonomy; (2)
reviewing a critical subset of sensor technologies that allow a machine to
sense human states; and (3) distilling some critical questions for advancing
the field of trusted autonomy. The inquiry is augmented with conceptual models
that we propose along the way by recompiling and reshaping the literature into
forms that enables trusted autonomous systems to become a reality. The paper
offers a vision for a Trusted Cyborg Swarm, an extension of our previous
Cognitive Cyber Symbiosis concept, whereby humans and machines meld together in
a harmonious, seamless, and coordinated manner.


title: Recognition of unipolar and generalised split graphs

abstract:
  A graph is unipolar if it can be partitioned into a clique and a disjoint
union of cliques, and a graph is a generalised split graph if it or its
complement is unipolar. A unipolar partition of a graph can be used to find
efficiently the clique number, the stability number, the chromatic number, and
to solve other problems that are hard for general graphs. We present the first
$O(n^2)$ time algorithm for recognition of $n$-vertex unipolar and generalised
split graphs, improving on previous $O(n^3)$ time algorithms.


title: Data-Efficient Off-Policy Policy Evaluation for Reinforcement Learning

abstract:
  In this paper we present a new way of predicting the performance of a
reinforcement learning policy given historical data that may have been
generated by a different policy. The ability to evaluate a policy from
historical data is important for applications where the deployment of a bad
policy can be dangerous or costly. We show empirically that our algorithm
produces estimates that often have orders of magnitude lower mean squared error
than existing methods---it makes more efficient use of the available data. Our
new estimator is based on two advances: an extension of the doubly robust
estimator (Jiang and Li, 2015), and a new way to mix between model based
estimates and importance sampling based estimates.


title: Orbit Closures and Invariants

abstract:
  Let G be a reductive linear algebraic group, H a reductive subgroup of G and
X an affine G-variety. Let Y denote the set of fixed points of H in X, and N(H)
the normalizer of H in G. In this paper we study the natural map from the
quotient of Y by N(H) to the quotient of X by G induced by the inclusion of Y
in X. We show that, given G and H, this map is a finite morphism for all
G-varieties X if and only if H is G-completely reducible (in the sense defined
by J-P. Serre); this was proved in characteristic zero by Luna in the 1970s. We
discuss some applications and give a criterion for the map of quotients to be
an isomorphism. We show how to extend some other results in Luna's paper to
positive characteristic and also prove the following theorem. Let H and K be
reductive subgroups of G; then the double coset HgK is closed for generic g in
G if and only if the intersection of generic conjugates of H and K is
reductive.


title: The role of flavon cross couplings in leptonic flavour mixing

abstract:
  In models with discrete flavour symmetries, flavons are critical to realise
specific flavour structures. Leptonic flavour mixing originates from the
misalignment of flavon vacuum expectation values which respect different
residual symmetries in the charged lepton and neutrino sectors. Flavon cross
couplings are usually forbidden, in order to protect these symmetries. Contrary
to this approach, we show that cross couplings can play a key role and give
raise to necessary corrections to flavour-mixing patterns, including a non-zero
value for the reactor angle and CP violation. For definiteness, we present two
models based on $A_4$. In the first model, all flavons are assumed to be real
or pseudo-real, with 7 real degrees of freedom in the flavon sector in total. A
sizable reactor angle associated with nearly maximal CP violation is achieved,
and, as both originate from the same cross coupling, a sum rule results with a
precise prediction for the value of the Dirac CP-violating phase. In the second
model, the flavons are taken to be complex scalars, which can be connected with
supersymmetric models and multi-Higgs models. The complexity properties of
flavons provide new sources for generating the reactor angle. Models in this
new approach introduce very few degrees of freedom beyond the Standard Model
and can be more economical than those in the framework of extra dimension or
supersymmetry.


title:
Dual Link Algorithm for the Weighted Sum Rate Maximization in MIMO
  Interference Channels

abstract:
  MIMO interference network optimization is important for increasingly crowded
wireless communication networks. We provide a new algorithm, named Dual Link
algorithm, for the classic problem of weighted sum-rate maximization for MIMO
multiaccess channels (MAC), broadcast channels (BC), and general MIMO
interference channels with Gaussian input and a total power constraint. For
MIMO MAC/BC, the algorithm finds optimal signals to achieve the capacity region
boundary. For interference channels with Gaussian input assumption, two of the
previous state-of-the-art algorithms are the WMMSE algorithm and the polite
water-filling (PWF) algorithm. The WMMSE algorithm is provably convergent,
while the PWF algorithm takes the advantage of the optimal transmit signal
structure and converges the fastest in most situations but is not guaranteed to
converge in all situations. It is highly desirable to design an algorithm that
has the advantages of both algorithms. The dual link algorithm is such an
algorithm. Its fast and guaranteed convergence is important to distributed
implementation and time varying channels. In addition, the technique and a
scaling invariance property used in the convergence proof may find applications
in other non-convex problems in communication networks.


title:
Total mean curvature, scalar curvature, and a variational analog of
  Brown-York mass

abstract:
  We study the supremum of the total mean curvature on the boundary of compact,
mean-convex 3-manifolds with nonnegative scalar curvature, and a prescribed
boundary metric. We establish an additivity property for this supremum and
exhibit rigidity for maximizers assuming the supremum is attained. When the
boundary consists of 2-spheres, we demonstrate that the finiteness of the
supremum follows from the previous work of Shi-Tam and Wang-Yau on the
quasi-local mass problem in general relativity. In turn, we define a
variational analog of Brown-York quasi-local mass without assuming that the
boundary 2-sphere has positive Gauss curvature.


title:
Entire solution in cylinder-like domains for a bistable
  reaction-diffusion equation

abstract:
  We construct nontrivial entire solutions for a bistable reaction-diffusion
equation in a class of domains that are unbounded in one direction. The
motivation comes from recent results of Berestycki, Bouhours, and Chapuisat
concerning propagation and blocking phenomena in infinite domains. A key
assumption in their study was the "cylinder-like" assumption: their domains are
supposed to be straight cylinders in a half space. The purpose of this paper is
to consider domains that tend to a straight cylinder in one direction.
  We also prove the existence of an entire solution for a one-dimensional
problem with a non-homogeneous linear term.