title: Correction terms and the non-orientable slice genus

abstract:
  By considering negative surgeries on a knot $K$ in $S^3$, we derive a lower
bound to the non-orientable slice genus $\gamma_4(K)$ in terms of the signature
$\sigma(K)$ and the concordance invariants $V_i(\overline{K})$, which
strengthens a previous bound given by Batson, and which coincides with
Ozsv\'ath-Stipsicz-Szab\'o's bound in terms of their $\upsilon$ invariant for
L-space knots and quasi-alternating knots. A curious feature of our bound is
superadditivity, implying, for instance, that the bound on the stable
non-orientable genus is sometimes better than the one on $\gamma_4(K)$.


title:
Dip-coating with prestructured substrates: transfer of simple liquids
  and Langmuir-Blodgett monolayers

abstract:
  When a plate is withdrawn from a liquid bath, either a static meniscus forms
in the transition region between the bath and the substrate or a liquid film of
finite thickness (a Landau-Levich film) is transferred onto the moving
substrate. If the substrate is inhomogeneous, e.g., has a prestructure
consisting of stripes of different wettabilities, the meniscus can be deformed
or show a complex dynamic behavior. Here we study the free surface shape and
dynamics of a dragged meniscus occurring for striped prestructures with two
orientations, parallel and perpendicular to the transfer direction. A thin film
model is employed that accounts for capillarity through a Laplace pressure and
for the spatially varying wettability through a Derjaguin (or disjoining)
pressure. Numerical continuation is used to obtain steady free surface profiles
and corresponding bifurcation diagrams in the case of substrates with different
homogeneous wettabilities. Direct numerical simulations are employed in the
case of the various striped prestructures. The final part illustrates the
importance of our findings for particular applications that involve complex
liquids by modeling a Langmuir-Blodgett transfer experiment. There, one
transfers a monolayer of an insoluble surfactant that covers the surface of the
bath onto the moving substrate. The resulting pattern formation phenomena can
be crucially influenced by the hydrodynamics of the liquid meniscus that itself
depends on the prestructure on the substrate. In particular, we show how
prestructure stripes parallel to the transfer direction lead to the formation
of bent stripes in the surfactant coverage after transfer and present similar
experimental results.


title: The Kinematic Image of RR, PR, and RP Dyads

abstract:
  We provide necessary and sufficient conditions for admissible transformations
in the projectivised dual quaternion model of rigid body displacements and we
characterise constraint varieties of dyads with revolute and prismatic joints
in this model. Projective transformations induced by coordinate changes in
moving and/or fixed frame fix the quadrics of a pencil and preserve the two
families of rulings of an exceptional three-dimensional quadric. The constraint
variety of a dyad with two revolute joints is a regular ruled quadric in a
three-space that contains a "null quadrilateral". If a revolute joint is
replaced by a prismatic joint, this quadrilateral collapses into a pair of
conjugate complex null lines and a real line but these properties are not
sufficient to characterise such dyads. We provide a complete characterisation
by introducing a new invariant, the "fiber projectivity", and we present
examples that demonstrate its potential to explain hitherto not sufficiently
well understood phenomena.


title: Compact Measurement Station for Low Energy Proton Beams

abstract:
  A compact, remote controlled, cost efficient diagnostic station has been
developed to measure the charge, the profile and the emittance for low energy
proton beams. It has been installed and tested in the proton beam line of the
Project Prometheus at SANAEM of the Turkish Atomic Energy Authority.


title: Digital lattice gauge theories

abstract:
  We propose a general scheme for a digital construction of lattice gauge
theories with dynamical fermions. In this method, the four-body interactions
arising in models with $2+1$ dimensions and higher, are obtained
stroboscopically, through a sequence of two-body interactions with ancillary
degrees of freedom. This yields stronger interactions than the ones obtained
through pertubative methods, as typically done in previous proposals, and
removes an important bottleneck in the road towards experimental realizations.
The scheme applies to generic gauge theories with Lie or finite symmetry
groups, both Abelian and non-Abelian. As a concrete example, we present the
construction of a digital quantum simulator for a $\mathbb{Z}_{3}$ lattice
gauge theory with dynamical fermionic matter in $2+1$ dimensions, using
ultracold atoms in optical lattices, involving three atomic species,
representing the matter, gauge and auxiliary degrees of freedom, that are
separated in three different layers. By moving the ancilla atoms with a proper
sequence of steps, we show how we can obtain the desired evolution in a clean,
controlled way.

categories: quant-ph cond-mat.quant-gas hep-lat hep-th


title: Half a state, half an operator: a general formulation of stators

abstract:
  Stators, which may be intuitively defined as "half states, half operators"
are mathematical objects which act on two Hilbert spaces and utilize
entanglement to create remote operations and exchange information between two
physical systems. In particular, they allow to induce effective dynamics on one
physical system by acting on the other one, given they have properly been
connected with the right stator. In this work, the concept of stators is
generalized and formalized in a way that allows the utilization of stators for
some physical problems based on symmetry groups, and in particular digital
quantum simulation.


title:
Design and Implementation of a Measurement-Based Policy-Driven Resource
  Management Framework For Converged Networks

abstract:
  This paper presents the design and implementation of a measurement-based QoS
and resource management framework, CNQF (Converged Networks QoS Management
Framework). CNQF is designed to provide unified, scalable QoS control and
resource management through the use of a policy-based network management
paradigm. It achieves this via distributed functional entities that are
deployed to co-ordinate the resources of the transport network through
centralized policy-driven decisions supported by measurement-based control
architecture. We present the CNQF architecture, implementation of the prototype
and validation of various inbuilt QoS control mechanisms using real traffic
flows on a Linux-based experimental test bed.


title: Free boundary problems in PDEs and particle systems

abstract:
  In this volume a theory for models of transport in the presence of a free
boundary is developed. Macroscopic laws of transport are described by PDEs.
When the system is open, there are several mechanisms to couple the system with
the external forces. Here a class of systems where the interaction with the
exterior takes place in correspondence of a free boundary is considered. Both
continuous and discrete models sharing the same structure are analyzed. In Part
I a free boundary problem related to the Stefan Problem is worked out in all
details. For this model a new notion of relaxed solution is proposed for which
global existence and uniqueness is proven. It is also shown that this is the
hydrodynamic limit of the empirical mass density of the associated particle
system. In Part II several other models are discussed. The expectation is that
the results proved for the basic model extend to these other cases. All the
models discussed in this volume have an interest in problems arising in several
research fields such as heat conduction, queuing theory, propagation of fire,
interface dynamics, population dynamics, evolution of biological systems with
selection mechanisms.In general researchers interested in the relations between
PDEs and stochastic processes can find in this volume an extension of this
correspondence to modern mathematical physics.

categories: math.PR cond-mat.stat-mech math-ph math.AP math.MP


title: Hunting for reduced polytopes

abstract:
  By correcting an example by Polyanskii, we show that there exist reduced
polytopes in three-dimensional Euclidean space. This partially answers the
question posed by Lassak on the existence of reduced polytopes in
$d$-dimensional Euclidean space for $d\geq 3$.


title: Connectivity, Dynamics, and Structure in a Tetrahedral Network Liquid

abstract:
  We report a detailed computational study by Brownian Dynamics simulations of
the structure and dynamics of a liquid of patchy particles which develops an
amorphous tetrahedral network upon decreasing temperature. The highly
directional particle interactions allows us to investigate the system
connectivity by discriminating the total set of particles into different
populations according to a penta-modal distribution of bonds per particle. With
this methodology we show how the particle bonding process is not randomly
independent but it manifests clear bond correlations at low temperatures. We
further explore the dynamics of the system in real space and establish a clear
relation between particle mobility and particle connectivity. In particular, we
provide evidence of anomalous diffusion at low temperatures and reveal how the
dynamics is affected by the short-time hopping motion of the weakly bounded
particles. Finally we widely investigate the dynamics and structure of the
system in Fourier space and identify two quantitatively similar length scales,
one dynamic and the other one static, which increase upon cooling the system
and reach distances of the order of few particle diameters. We summarize our
findings in a qualitative picture where the low temperature regime of the
viscoelastic liquid is understood in terms of an evolving network of long time
metastable cooperative domains of particles.


title:
Understanding and coping with extremism in an online collaborative
  environment

abstract:
  The Internet has provided us with great opportunities for large scale
collaborative public good projects. Wikipedia is a predominant example of such
projects where conflicts emerge and get resolved through bottom-up mechanisms
leading to the emergence of the largest encyclopedia in human history.
Disaccord arises whenever editors with different opinions try to produce an
article reflecting a consensual view. The debates are mainly heated by editors
with extremist views. Using a model of common value production, we show that
the consensus can only be reached if extremist groups can actively take part in
the discussion and if their views are also represented in the common outcome,
at least temporarily. We show that banning problematic editors mostly hinders
the consensus as it delays discussion and thus the whole consensus building
process. To validate the model, relevant quantities are measured both in
simulations and Wikipedia which show satisfactory agreement. We also consider
the role of direct communication between editors both in the model and in
Wikipedia data (by analysing the Wikipedia {\it talk} pages). While the model
suggests that in certain conditions there is an optimal rate of "talking" vs
"editing", it correctly predicts that in the current settings of Wikipedia,
more activity in talk pages is associated with more controversy.


title:
Keep it SMPL: Automatic Estimation of 3D Human Pose and Shape from a
  Single Image

abstract:
  We describe the first method to automatically estimate the 3D pose of the
human body as well as its 3D shape from a single unconstrained image. We
estimate a full 3D mesh and show that 2D joints alone carry a surprising amount
of information about body shape. The problem is challenging because of the
complexity of the human body, articulation, occlusion, clothing, lighting, and
the inherent ambiguity in inferring 3D from 2D. To solve this, we first use a
recently published CNN-based method, DeepCut, to predict (bottom-up) the 2D
body joint locations. We then fit (top-down) a recently published statistical
body shape model, called SMPL, to the 2D joints. We do so by minimizing an
objective function that penalizes the error between the projected 3D model
joints and detected 2D joints. Because SMPL captures correlations in human
shape across the population, we are able to robustly fit it to very little
data. We further leverage the 3D model to prevent solutions that cause
interpenetration. We evaluate our method, SMPLify, on the Leeds Sports,
HumanEva, and Human3.6M datasets, showing superior pose accuracy with respect
to the state of the art.


title:
Spatial probabilistic pulsatility model for enhancing
  photoplethysmographic imaging systems

abstract:
  Photolethysmographic imaging (PPGI) is a widefield non-contact biophotonic
technology able to remotely monitor cardiovascular function over anatomical
areas. Though spatial context can provide increased physiological insight,
existing PPGI systems rely on coarse spatial averaging with no anatomical
priors for assessing arterial pulsatility. Here, we developed a continuous
probabilistic pulsatility model for importance-weighted blood pulse waveform
extraction. Using a data-driven approach, the model was constructed using a 23
participant sample with large demographic variation (11/12 female/male, age
11-60 years, BMI 16.4-35.1 kg$\cdot$m$^{-2}$). Using time-synchronized
ground-truth waveforms, spatial correlation priors were computed and projected
into a co-aligned importance-weighted Cartesian space. A modified
Parzen-Rosenblatt kernel density estimation method was used to compute the
continuous resolution-agnostic probabilistic pulsatility model. The model
identified locations that consistently exhibited pulsatility across the sample.
Blood pulse waveform signals extracted with the model exhibited significantly
stronger temporal correlation ($W=35,p<0.01$) and spectral SNR ($W=31,p<0.01$)
compared to uniform spatial averaging. Heart rate estimation was in strong
agreement with true heart rate ($r^2=0.9619$, error $(\mu,\sigma)=(0.52,1.69)$
bpm).


title: A finite Hausdorff dimension for graphs

abstract:
  The classical Hausdorff dimension of finite or countable metric spaces is
zero. Recently, we defined a variant, called \emph{finite Hausdorff dimension},
which is not necessarily trivial on finite metric spaces. In this paper we
apply this to connected simple graphs, a class that provides many interesting
examples of finite metric spaces. There are two very different cases: one in
which the distance is coarse (and one is doing Graph Theory), and another case
in which the distance is much finer (and one is somewhere between graphs and
finite metric spaces).


title: Neuromorphic Robot Dream

abstract:
  In this paper we present the next step in our approach to neurobiologically
plausible implementation of emotional reactions and behaviors for real-time
autonomous robotic systems. The working metaphor we use is the "day" and the
"night" phases of mammalian life. During the "day phase" a robotic system
stores the inbound information and is controlled by a light-weight rule-based
system in real time. In contrast to that, during the "night phase" information
that has been stored is transferred to a supercomputing system to update the
realistic neural network: emotional and behavioral strategies.


title: Diffusion processes on branching Brownian motion

abstract:
  We construct a class of one-dimensional diffusion processes on the particles
of branching Brownian motion that are symmetric with respect to the limits of
random martingale measures. These measures are associated with the extended
extremal process of branching Brownian motion and are supported on a
Cantor-like set. The processes are obtained via a time-change of a standard
one-dimensional reflected Brownian motion on $\mathbb{R}_+$ in terms of the
associated positive continuous additive functionals. The processes introduced
in this paper may be regarded as an analogue of the Liouville Brownian motion
which has been recently constructed in the context of a Gaussian free field.


title:
Electroweak Vacuum Instability and Renormalized Higgs Field Vacuum
  Fluctuations in the Inflationary Universe

abstract:
  In this work, we investigated the electroweak vacuum instability during or
after inflation. In the inflationary Universe, i.e., de Sitter space, the
vacuum field fluctuations $\left< {\delta \phi }^{ 2 } \right>$ enlarge in
proportion to the Hubble scale $H^{2}$. Therefore, the large inflationary
vacuum fluctuations of the Higgs field $\left< {\delta \phi }^{ 2 } \right>$
are potentially catastrophic to trigger the vacuum transition to the
negative-energy Planck-scale vacuum state and cause an immediate collapse of
the Universe. However, the vacuum field fluctuations $\left< {\delta \phi }^{ 2
} \right>$, i.e., the vacuum expectation values have an ultraviolet divergence,
and therefore a renormalization is necessary to estimate the physical effects
of the vacuum transition. Thus, in this paper, we revisit the electroweak
vacuum instability from the perspective of quantum field theory (QFT) in curved
space-time, and discuss the dynamical behavior of the homogeneous Higgs field
$\phi$ determined by the effective potential ${ V }_{\rm eff}\left( \phi
\right)$ in curved space-time and the renormalized vacuum fluctuations $\left<
{\delta \phi }^{ 2 } \right>_{\rm ren}$ via adiabatic regularization and
point-splitting regularization. We simply suppose that the Higgs field only
couples the gravity via the non-minimal Higgs-gravity coupling $\xi(\mu)$. In
this scenario, the electroweak vacuum stability is inevitably threatened by the
dynamical behavior of the homogeneous Higgs field $\phi$, or the formations of
AdS domains or bubbles unless the Hubble scale is small enough $H< \Lambda_{I}
$.


title:
Three-Dimensional Geometry of Magnetic Reconnection Induced by
  Ballooning Instability in a Generalized Harris Sheet

abstract:
  We report for the first time the intrinsically three-dimensional (3D)
geometry of the magnetic reconnection process induced by ballooning instability
in a generalized Harris sheet. The spatial distribution and structure of the
quasi-separatrix layers, as well as their temporal emergence and evolution,
indicate that the associated magnetic reconnection can only occur in a 3D
geometry, which is irreducible to that of any two-dimensional reconnection
process. Such a finding provides a new perspective to the long-standing
controversy over the substorm onset problem, and elucidates the combined roles
of reconnection and ballooning instabilities. It also connects to the universal
presence of 3D reconnection processes previously discovered in various natural
and laboratory plasmas.


title: Regularity of solutions to anisotropic nonlocal equations

abstract:
  We study harmonic functions associated to systems of stochastic differential
equations of the form
$dX_t^i=A_{i1}(X_{t-})dZ_t^1+\cdots+A_{id}(X_{t-})dZ_t^d$, $i\in\{1,\dots,d\}$,
where $Z_t^j$ are independent one-dimensional symmetric stable processes with
indices $\alpha_j\in(0,2)$, $j\in\{1,\dots,d\}$. In this article we prove
H\"older regularity of bounded harmonic functions with respect to solutions to
such systems.


title: Hopf Algebraic Structure for Tagged Graphs and Topological Recursion

abstract:
  Using the shuffle structure of the graphs, we introduce a new kind of the
Hopf algebraic structure for tagged graphs with, or without loops. Like a
quantum group structure, its product is non-commutative. With the help of the
Hopf algebraic structure, after taking account symmetry of the tagged graphs,
we reconstruct the topological recursion on spectral curves proposed by B.
Eynard and N. Orantin, which includes the one-loop equations of various matrix
integrals as special cases.


title: $I$-functions of Calabi--Yau 3-folds in Grassmannians

abstract:
  We study $I$-functions of Calabi--Yau 3-folds with Picard number one which
are zero loci of general sections of direct sums of globally generated
irreducible homogeneous vector bundles on Grassmannians.


title: Collision-free Operation in High Density WLAN Deployments

abstract:
  WiFi's popularity has led to crowded scenarios composed of many Access Points
(AP) and clients, often operating on overlapping channels, producing
interference that gravely degrades performance. This misallocation of resources
is often the result of multiple WLANs ownership, that is, networks are
frequently setup automatically without considering neighbouring APs. In this
work we overview the effect of Overlapping BSS (OBSS) from the perspective of
the MAC layer, taking special interest on describing the advantages of
eliminating collisions with Carrier Sense Multiple Access with Enhanced
Collision Avoidance (CSMA/ECA). We propose a single Access Point (AP) and
several multi-AP scenarios, including the residential building example proposed
for testing the upcoming IEEE 802.11ax amendment. Results using the first NS-3
implementation of CSMA/ECA reveal the advantage of CSMA/ECA's deterministic
backoff contention technique, confirming its suitability for very crowded
scenarios.


title:
Inducing and Mitigating a Self-Reinforcing Degradation in
  Decision-making Teams

abstract:
  The models in this paper demonstrate how self-reinforcing error due to
positive feedback can lead to overload and saturation of decision-making
elements, and ultimately the cascading collapse of an organization due to the
propagation of overload and erroneous decisions throughout the organization. We
begin the paper with an analysis of the stability of the decision-making
aspects of command organizations from a system-theoretic perspective. A simple
dynamic model shows how an organization can enter into a self-reinforcing cycle
of increasing decision workload until the demand for decisions exceeds the
decision-making capacity of the organization. We then extend the model to more
complex networked organizations and show that they also experience a form of
self-reinforcing degradation. In particular, we find that the degradation in
decision quality has a tendency to propagate through the hierarchical
structure, i.e. overload at one location affects other locations by overloading
the higher-level components which then in turn overload their subordinates. Our
computational experiments suggest several strategies for mitigating this type
of malfunction: dumping excessive load, empowering lower echelons, minimizing
the need for coordination, using command-by-negation, insulating weak
performers, and applying on-line diagnostics. We describe a method to allocate
decision responsibility and arrange information flow dynamically within a team
of decision-makers for command and control.


title: Practical repeaters for ultra-long distance quantum communication

abstract:
  Quantum communication is at the forefront of quantum technology, enabling the
development of absolutely secure encryption, distributed quantum computing,
teleportation and more. Whilst quantum communication has been experimentally
demonstrated at distances on the order of hundreds of kilometers, the
establishment of high-fidelity pairs shared over larger distances remains a
formidable technical challenge due to attenuation. However, this may be
overcome with the use of quantum repeaters. Here we propose a method to
construct a robust quantum repeater network using only existing technology. Our
protocol is able to perform all parts of the procedure in a way that is highly
tolerant to photon loss and imperfections in detectors, and it achieves secure
bit rates on the order of kilohertz over intercontinental distances.


title:
Bayesian Nonparametric Modelling of Joint Gap Time Distributions for
  Recurrent Event Data

abstract:
  We propose autoregressive Bayesian semi-parametric models for waiting times
between recurrent events. The aim is two-fold: inference on the effect of
possibly time-varying covariates on the gap times and clustering of individuals
based on the time trajectory of the recurrent event. Time-dependency between
gap times is taken into account through the specification of an autoregressive
component for the random effects parameters influencing the response at
different times. The order of the autoregression may be assumed unknown and
object of inference and we consider two alternative approaches to perform model
selection under this scenario. Covariates may be easily included in the
regression framework and censoring and missing data are easily accounted for.
As the proposed methodologies lies within the class of Dirichlet process
mixtures, posterior inference can be performed through efficient MCMC
algorithms. We illustrate the approach through simulations and medical
applications involving recurrent hospitalizations of cancer patients and
successive urinary tract infections.


title:
Search for dark matter annihilations towards the inner Galactic halo
  from 10 years of observations with H.E.S.S

abstract:
  The inner region of the Milky Way halo harbors a large amount of dark matter
(DM). Given its proximity, it is one of the most promising targets to look for
DM. We report on a search for the annihilations of DM particles using
$\gamma$-ray observations towards the inner 300 parsecs of the Milky Way, with
the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based
on a 2D maximum likelihood method using Galactic center (GC) data accumulated
by H.E.S.S. over the last 10 years (2004-2014), and does not show any
significant $\gamma$-ray signal above background. Assuming Einasto and
Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on
the annihilation cross section $\langle \sigma v\rangle$. These constraints are
the strongest obtained so far in the TeV DM mass range and improve upon
previous limits by a factor 5. For the Einasto profile, the constraints reach
$\langle \sigma v\rangle$ values of $\rm 6\times10^{-26} cm^3s^{-1}$ in the
$W^+W^-$ channel for a DM particle mass of 1.5 TeV, and $\rm 2\times10^{-26}
cm^3s^{-1}$ in the $\tau^+\tau^-$ channel for 1 TeV mass. For the first time,
ground-based $\gamma$-ray observations have reached sufficient sensitivity to
probe $\langle \sigma v\rangle$ values expected from the thermal relic density
for TeV DM particles.


title:
Hamiltonian approach to QCD in Coulomb gauge: Gribov's confinement
  scenario at work

abstract:
  I will review essential features of the Hamiltonian approach to QCD in
Coulomb gauge showing that Gribov's confinement scenario is realized in this
gauge. For this purpose I will discuss in detail the emergence of the horizon
condition and the Coulomb string tension. I will show that both are induced by
center vortex gauge field configurations, which establish the connection
between Gribov's confinement scenario and the center vortex picture of
confinement. I will then extend the Hamiltonian approach to QCD in Coulomb
gauge to finite temperatures, first by the usual grand canonical ensemble and
second by the compactification of a spatial dimension. I will present results
for the pressure, energy density and interaction measure as well as for the
Polyakov loop.


title: Hermitian Azumaya modules and arithmetic Chern classes

abstract:
  We compute arithmetic Chern classes of sheaves on an arithmetic surface X
associated to a Hermitian Azumaya algebra.


title: Rapid and catalyst-free CVD growth of graphene on hBN

abstract:
  Recently, hexagonal boron nitride (h-BN) has been shown to act as an ideal
substrate to graphene by greatly improving the material transport properties
thanks to its atomically flat surface, low interlayer electronic coupling and
almost perfect reticular matching. Chemical vapour deposition (CVD) is
presently considered the most scalable approach to grow graphene directly on
h-BN. However, for the catalyst-free approach, poor control over the shape and
crystallinity of the graphene grains and low growth rates are typically
reported. In this work we investigate the crystallinity of differently shaped
grains and identify a path towards a real van der Waals epitaxy of graphene on
h-BN by adopting a catalyst-free CVD process. We demonstrate the
polycrystalline nature of circular-shaped pads and attribute the stemming of
different oriented grains to airborne contamination of the h-BN flakes. We show
that single-crystal grains with six-fold symmetry can be obtained by adopting
high hydrogen partial pressures during growth. Notably, growth rates as high as
100 nm/min are obtained by optimizing growth temperature and pressure. The
possibility of synthesizing single-crystal graphene on h-BN with appreciable
growth rates by adopting a simple CVD approach is a step towards an increased
accessibility of this promising van der Waals heterostructure.


title: Quantum paraelectricity probed by superconducting resonators

abstract:
  Superconducting coplanar waveguide (CPW), resonators are powerful and
versatile tools used in areas ranging from radiation detection to circuit
quantum electrodynamics. Their potential for low intrinsic losses makes them
attractive as sensitive probes of electronic properties of bulk materials and
thin films. Here we use superconducting MoRe CPW resonators, to investigate the
high-frequency (up to 0.3 GHz) and low temperature (down to 3.5 K) permittivity
of SrTiO3, a non-linear dielectric on the verge of a ferroelectric transition
(quantum paraelectricity). We perform a quantitative analysis of its dielectric
properties as a function of external dc bias (up to +-15V), rf power and mode
number and discuss our results within the framework of the most recent
theoretical models. We also discuss the origin of a fatigue effect that reduces
the tunability of the dielectric constant of SrTiO3, which we relate to the
presence of oxygen vacancies.


title:
Influence of Stellar Flares on the Chemical Composition of Exoplanets
  and Spectra

abstract:
  More than 3000 exoplanets have been detected so far, and more and more
spectroscopic observations of exoplanets are performed. Future instruments are
eagerly awaited as they will be able to provide spectroscopic data with a
greater accuracy and sensitivity than what is currently available. An important
aspect to consider is temporal stellar atmospheric disturbances that can
influence the planetary composition, and hence spectra, and potentially can
lead to incorrect assumptions about the steady-state atmospheric composition of
the planet. We focus on perturbations that come from the host star in the form
of flare events that significantly increase the photon flux impingement on the
exoplanet atmosphere. In some cases, and particularly for M stars, this sudden
increase may last for several hours. We aim at answering the question to what
extent a stellar flare is able to modify the chemical composition of the
planetary atmosphere and, therefore influence the resulting spectra. We use a
1D thermo-photochemical model to study the neutral atmospheric composition of
two hypothetic planets located around the star AD Leo. This active star has
already been observed during a flare. We use the spectroscopic data from this
flare event to simulate the evolution of the chemical composition of the
atmospheres of the two hypothetic planets. We compute synthetic spectra to
evaluate the implications for observations. The increase of the incoming photon
flux affects the chemical abundances of some important species down to
altitudes associated with an atmospheric pressure of 1 bar, that can lead to
variations in planetary spectra if performed during transit.


title:
Dualizing involutions for classical and similitude groups over local
  non-archimedean fields

abstract:
  Building on ideas of Tupan, we give an elementary proof of a result of
M{\oe}glin, Vign\'{e}ras and Waldspurger on the existence of automorphisms of
many $p$-adic classical groups that take each irreducible smooth
representations to its dual. Our proof also applies to the corresponding
similitude groups.


title: N-opcode Analysis for Android Malware Classification and Categorization

abstract:
  Malware detection is a growing problem particularly on the Android mobile
platform due to its increasing popularity and accessibility to numerous third
party app markets. This has also been made worse by the increasingly
sophisticated detection avoidance techniques employed by emerging malware
families. This calls for more effective techniques for detection and
classification of Android malware. Hence, in this paper we present an n-opcode
analysis based approach that utilizes machine learning to classify and
categorize Android malware. This approach enables automated feature discovery
that eliminates the need for applying expert or domain knowledge to define the
needed features. Our experiments on 2520 samples that were performed using up
to 10-gram opcode features showed that an f-measure of 98% is achievable using
this approach.


title: Hitchin Pairs for non-compact real Lie groups

abstract:
  Hitchin pairs on Riemann surfaces are generalizations of Higgs bundles,
allowing the Higgs field to be twisted by an arbitrary line bundle. We consider
this generalization in the context of $G$-Higgs bundles for a real reductive
Lie group $G$. We outline the basic theory and review some selected results,
including recent results by Nozad and the author arXiv:1602.02712 [math.AG] on
Hitchin pairs for the unitary group of indefinite signature $\mathrm{U}(p,q)$.


title:
Darboux transformations and exact soliton solutions of integrable
  coupled spin systems related with the Manakov system

abstract:
  We construct a Darboux transformation of a general $su(3)$-valued spin system
called the $\Gamma$-spin system. Using this Darboux transformation we derive a
recursive formula for the soliton solutions of this spin system. Then using
these results we present explicit expressions for the 1-soliton solution of the
coupled $su(2)$-valued spin systems, namely, of the coupled M-LIII equation.


title: Multicolour containers and the entropy of decorated graph limits

abstract:
  In recent breakthrough results, Saxton--Thomason and Balogh--Morris--Samotij
have developed powerful theories of hypergraph containers. These theories have
led to a large number of new results on transference, and on counting and
characterising typical graphs in hereditary properties. In a different
direction, Hatami--Janson--Szegedy proved results on the entropy of graph
limits which count and characterise graphs in dense hereditary properties.
  In this paper, we make a threefold contribution to this area of research:
  1) We generalise results of Saxton--Thomason to obtain container theorems for
general, dense hereditary properties of multicoloured graphs. Our main tool is
the adoption of an entropy-based framework. As corollaries, we obtain general
counting, characterization and transference results. We further extend our
results to cover a variety of combinatorial structures: directed graphs,
oriented graphs, tournaments, multipartite graphs, multi-graphs, hypercubes and
hypergraphs.
  2) We generalise the results of Hatami--Janson--Szegedy on the entropy of
graph limits to the setting of decorated graph limits. In particular we define
a cut norm for decorated graph limits and prove compactness of the space of
decorated graph limits under that norm.
  3) We explore a weak equivalence between the container and graph limit
approaches to counting and characterising graphs in hereditary properties. In
one direction, we show how our multicolour container results may be used to
recover decorated versions of the results of Hatami--Janson--Szegedy. In the
other direction, we show that our decorated extensions of
Hatami--Janson--Szegedy's results on graph limits imply counting and
characterization applications.
  Similar container results were recently obtained independently by Terry.


title: Spherical 2-Dupin submanifolds

abstract:
  We show that every spherical 2-Dupin submanifold that is not a hypersurface
is conformally congruent to the standard embedding of the real, complex,
quaternionic or octonionic projective plane. We also classify 2-CPC,
2-umbilical and weakly 2-umbilical submanifolds in space forms.


title:
Contact-line pinning controls how quickly colloidal particles
  equilibrate with liquid interfaces

abstract:
  Previous experiments have shown that spherical colloidal particles relax to
equilibrium slowly after they adsorb to a liquid-liquid interface, despite the
large interfacial energy gradient driving the adsorption. The slow relaxation
has been explained in terms of transient pinning and depinning of the contact
line on the surface of the particles. However, the nature of the pinning sites
has not been investigated in detail. We use digital holographic microscopy to
track a variety of colloidal spheres---inorganic and organic, charge-stabilized
and sterically stabilized, aqueous and non-aqueous---as they breach liquid
interfaces. We find that nearly all of these particles relax logarithmically in
time over timescales much larger than those expected from viscous dissipation
alone. By comparing our results to theoretical models of the pinning dynamics,
we infer the area per defect to be on the order of a few square nanometers for
each of the colloids we examine, whereas the energy per defect can vary from a
few $kT$ for non-aqueous and inorganic spheres to tens of $kT$ for aqueous
polymer particles. The results suggest that the likely pinning sites are
topographical features inherent to colloidal particles---surface roughness in
the case of silica particles and grafted polymer "hairs" in the case of polymer
particles. We conclude that the slow relaxation must be taken into account in
experiments and applications, such as Pickering emulsions, that involve
colloids attaching to interfaces. The effect is particularly important for
aqueous polymer particles, which pin the contact line strongly.


title: Entangled States and the Gravitational Quantum Well

abstract:
  We study the continuous variable entanglement of a system of two particles
under the influence of Earth's gravitational field. We determine a phase-space
description of this bipartite system by calculating its Wigner function and
verify its entanglement by applying a generalization of the PPT criterion for
non-Gaussian states. We also examine the influence of gravity on an idealized
entanglement protocol to be shared between stations at different potentials
based on the correlation of states of the gravitational quantum well.


title:
Remember the Curse of Dimensionality: The Case of Goodness-of-Fit
  Testing in Arbitrary Dimension

abstract:
  Despite a substantial literature on nonparametric two-sample goodness-of-fit
testing in arbitrary dimensions spanning decades, there is no mention there of
any curse of dimensionality. Only more recently Ramdas et al. (2015) have
discussed this issue in the context of kernel methods by showing that their
performance degrades with the dimension even when the underlying distributions
are isotropic Gaussians. We take a minimax perspective and follow in the
footsteps of Ingster (1987) to derive the minimax rate in arbitrary dimension
when the discrepancy is measured in the L2 metric. That rate is revealed to be
nonparametric and exhibit a prototypical curse of dimensionality. We further
extend Ingster's work to show that the chi-squared test achieves the minimax
rate. Moreover, we show that the test can be made to work when the
distributions have support of low intrinsic dimension. Finally, inspired by
Ingster (2000), we consider a multiscale version of the chi-square test which
can adapt to unknown smoothness and/or unknown intrinsic dimensionality without
much loss in power.


title:
Dark Matter directional detection: comparison of the track direction
  determination

abstract:
  Several directional techniques have been proposed for a directional detection
of Dark matter, among others anisotropic crystal detectors, nuclear emulsion
plates, and low-pressure gaseous TPCs. The key point is to get access to the
initial direction of the nucleus recoiling due to the elastic scattering by a
WIMP. In this article, we aim at estimating, for each method, how the
information of the recoil track initial direction is preserved in different
detector materials. We use the SRIM simulation code to emulate the motion of
the first recoiling nucleus in each material. We propose the use of a new
observable, D, to quantify the preservation of the initial direction of the
recoiling nucleus in the detector. We show that in an emulsion mix and an
anisotropic crystal, the initial direction is lost very early, while in a
typical TPC gas mix, the direction is well preserved.


title:
The gaseous debris disk of the white dwarf SDSS J1228+1040. HST/COS
  search for far-ultraviolet signatures

abstract:
  Gaseous and dust debris disks around white dwarfs (WDs) are formed from
tidally disrupted planetary bodies. This offers an opportunity to determine the
composition of exoplanetary material by measuring element abundances in the
accreting WD's atmosphere. A more direct way to do this is through spectral
analysis of the disks themselves. Currently, the number of chemical elements
detected through disk emission-lines is smaller than that of species detected
through lines in the WD atmospheres.
  We assess the far-ultraviolet (FUV) spectrum of one well-studied object (SDSS
J122859.93+104032.9) to search for disk signatures at wavelengths <1050
angstrom, where the broad absorption lines of the Lyman series effectively
block the WD photospheric flux. We performed FUV observations (950-1240
angstrom) with the Hubble Space Telescope/Cosmic Origins Spectrograph and used
archival optical spectra. We compared them with non-local thermodynamic
equilibrium model spectra. In addition, we investigate the Ca II infrared
triplet (IRT) line profiles to constrain disk geometry and composition.
  No disk emission-lines were detected in the FUV spectrum, indicating that the
disk effective temperature is about 5000K. The long-time variability of the Ca
II IRT was reproduced with a precessing disk model of bulk Earth-like
composition, having a surface mass density of 0.3g/cm2 and an extension from 55
to 90 WD radii. The disk has a spiral shape that precesses with a period of
approximately 37 years, confirming previous results.


title:
A Hybrid High-Order method for the steady incompressible Navier--Stokes
  problem

abstract:
  In this work we introduce and analyze a novel Hybrid High-Order method for
the steady incompressible Navier-Stokes equations. The proposed method is
inf-sup stable on general polyhedral meshes, supports arbitrary approximation
orders, and is (relatively) inexpensive thanks to the possibility of statically
condensing a subset of the unknowns at each nonlinear iteration. We show under
general assumptions the existence of a discrete solution, which is also unique
provided a data smallness condition is verified. Using a compactness argument,
we prove convergence of the sequence of discrete solutions to minimal
regularity exact solutions for general data. For more regular solutions, we
prove optimal convergence rates for the energy-norm of the velocity and the
$L^2$-norm of the pressure under a standard data smallness assumption. More
precisely, when polynomials of degree $k\ge 0$ at mesh elements and faces are
used, both quantities are proved to converge as $h^{k+1}$ (with $h$ denoting
the meshsize).


title:
Magnetic field effects on the static quark potential at zero and finite
  temperature

abstract:
  We investigate the static $Q\bar{Q}$ potential at zero and finite temperature
in the presence of a constant and uniform external magnetic field $\vec{B}$,
for several values of the lattice spacing and for different orientations with
respect to $\vec{B}$. As a byproduct, we provide continuum limit extrapolated
results for the string tension, the Coulomb coupling and the Sommer parameter
at $T = 0$ and $B = 0$. We confirm the presence in the continuum of a
$B$-induced anisotropy, regarding essentially the string tension, for which it
is of the order of 15\% at $|e| B \sim 1~{\rm GeV}^2$ and would suggest, if
extrapolated to larger fields, a vanishing string tension along the magnetic
field for $|e| B \gtrsim 4$ GeV$^2$. The angular dependence for $|e| B \lesssim
1$ GeV$^2$ can be nicely parametrized by the first allowed term in an angular
Fourier expansion, corresponding to a quadrupole deformation. Finally, for $T
\neq 0$, the main effect of the magnetic field is a general suppression of the
string tension, leading to a precocious loss of the confining properties: this
happens even before the appearance of inverse magnetic catalysis in the chiral
condensate, supporting the idea that the influence of the magnetic field on the
confining properties is the leading effect originating the decrease of $T_c$ as
a function of $B$.


title: Network-Guided Biomarker Discovery

abstract:
  Identifying measurable genetic indicators (or biomarkers) of a specific
condition of a biological system is a key element of precision medicine. Indeed
it allows to tailor diagnostic, prognostic and treatment choice to individual
characteristics of a patient. In machine learning terms, biomarker discovery
can be framed as a feature selection problem on whole-genome data sets.
However, classical feature selection methods are usually underpowered to
process these data sets, which contain orders of magnitude more features than
samples. This can be addressed by making the assumption that genetic features
that are linked on a biological network are more likely to work jointly towards
explaining the phenotype of interest. We review here three families of methods
for feature selection that integrate prior knowledge in the form of networks.


title: Realistic Detectability of Close Interstellar Comets

abstract:
  During the planet formation process, billions of comets are created and
ejected into interstellar space. The detection and characterization of such
interstellar comets (also known as extra-solar planetesimals or extra-solar
comets) would give us in situ information about the efficiency and properties
of planet formation throughout the galaxy. However, no interstellar comets have
ever been detected, despite the fact that their hyperbolic orbits would make
them readily identifiable as unrelated to the solar system. Moro-Mart\'in et
al. 2009 have made a detailed and reasonable estimate of the properties of the
interstellar comet population. We extend their estimates of detectability with
a numerical model that allows us to consider "close" interstellar comets, e.g.,
those that come within the orbit of Jupiter. We include several constraints on
a "detectable" object that allow for realistic estimates of the frequency of
detections expected from the Large Synoptic Survey Telescope (LSST) and other
surveys. The influence of several of the assumed model parameters on the
frequency of detections is explored in detail. Based on the expectation from
Moro-Mart\'in et al. 2009, we expect that LSST will detect 0.001-10
interstellar comets during its nominal 10-year lifetime, with most of the
uncertainty from the unknown number density of small (nuclei of $\sim$0.1-1 km)
interstellar comets. Using simulated LSST-like astrometric data, we study the
problem of orbit determination for these bodies, finding that LSST could
identify their orbits as hyperbolic and determine an ephemeris sufficiently
accurate for follow-up in about 4-7 days. We give the hyperbolic orbital
parameters of the most detectable interstellar comets. Taking the results into
consideration, we give recommendations to future searches for interstellar
comets.


title: Lectures on the triangulation conjecture

abstract:
  We outline the proof that non-triangulable manifolds exist in any dimension
greater than four. The arguments involve homology cobordism invariants coming
from the Pin(2) symmetry of the Seiberg-Witten equations. We also explore a
related construction, of an involutive version of Heegaard Floer homology.


title:
Anderson transition of cold atoms with synthetic spin-orbit coupling in
  two-dimensional speckle potentials

abstract:
  We investigate the metal-insulator transition occurring in two-dimensional
(2D) systems of noninteracting atoms in the presence of artificial spin-orbit
interactions and a spatially correlated disorder generated by laser speckles.
Based on a high order discretization scheme, we calculate the precise position
of the mobility edge and verify that the transition belongs to the symplectic
universality class. We show that the mobility edge depends strongly on the
mixing angle between Rashba and Dresselhaus spin-orbit couplings. For equal
couplings a non-power-law divergence is found, signaling the crossing to the
orthogonal class, where such a 2D transition is forbidden.


title:
Deep probing of the photospheric sunspot penumbra: no evidence for
  magnetic field-free gaps

abstract:
  Some models for the topology of the magnetic field in sunspot penumbrae
predict the existence of field-free or dynamically weak-field regions in the
deep Photosphere. To confirm or rule out the existence of weak-field regions in
the deepest photospheric layers of the penumbra. The magnetic field at
$\log\tau_5=0$ is investigated by means of inversions of spectropolarimetric
data of two different sunspots located very close to disk center with a spatial
resolution of approximately 0.4-0.45 arcsec. The data have been recorded using
the GRIS instrument attached to the 1.5-meters GREGOR solar telescope at El
Teide observatory. It includes three Fe I lines around 1565 nm, whose
sensitivity to the magnetic field peaks at half a pressure-scale-height deeper
than the sensitivity of the widely used Fe I spectral line pair at 630 nm.
Prior to the inversion, the data is corrected for the effects of scattered
light using a deconvolution method with several point spread functions. At
$\log\tau_5=0$ we find no evidence for the existence of regions with
dynamically weak ($B<500$ Gauss) magnetic fields in sunspot penumbrae. This
result is much more reliable than previous investigations done with Fe I lines
at 630 nm. Moreover, the result is independent of the number of nodes employed
in the inversion, and also independent of the point spread function used to
deconvolve the data, and does not depend on the amount of straylight (i.e.
wide-angle scattered light) considered.


title:
DynaLog: An automated dynamic analysis framework for characterizing
  Android applications

abstract:
  Android is becoming ubiquitous and currently has the largest share of the
mobile OS market with billions of application downloads from the official app
market. It has also become the platform most targeted by mobile malware that
are becoming more sophisticated to evade state-of-the-art detection approaches.
Many Android malware families employ obfuscation techniques in order to avoid
detection and this may defeat static analysis based approaches. Dynamic
analysis on the other hand may be used to overcome this limitation. Hence in
this paper we propose DynaLog, a dynamic analysis based framework for
characterizing Android applications. The framework provides the capability to
analyse the behaviour of applications based on an extensive number of dynamic
features. It provides an automated platform for mass analysis and
characterization of apps that is useful for quickly identifying and isolating
malicious applications. The DynaLog framework leverages existing open source
tools to extract and log high level behaviours, API calls, and critical events
that can be used to explore the characteristics of an application, thus
providing an extensible dynamic analysis platform for detecting Android
malware. DynaLog is evaluated using real malware samples and clean applications
demonstrating its capabilities for effective analysis and detection of
malicious applications.


title:
Effects of contact-line pinning on the adsorption of nonspherical
  colloids at liquid interfaces

abstract:
  The effects of contact-line pinning are well-known in macroscopic systems,
but are only just beginning to be explored at the microscale in colloidal
suspensions. We use digital holography to capture the fast three-dimensional
dynamics of micrometer-sized ellipsoids breaching an oil-water interface. We
find that the particle angle varies approximately linearly with the height, in
contrast to results from simulations based on minimization of the interfacial
energy. Using a simple model of the motion of the contact line, we show that
the observed coupling between translational and rotational degrees of freedom
is likely due to contact-line pinning. We conclude that the dynamics of
colloidal particles adsorbing to a liquid interface are not determined by
minimization of interfacial energy and viscous dissipation alone; contact-line
pinning dictates both the timescale and pathway to equilibrium.


title:
Adaptive Versus Non-Adaptive Strategies in the Quantum Setting with
  Applications

abstract:
  We prove a general relation between adaptive and non-adaptive strategies in
the quantum setting, i.e., between strategies where the adversary can or cannot
adaptively base its action on some auxiliary quantum side information. Our
relation holds in a very general setting, and is applicable as long as we can
control the bit-size of the side information, or, more generally, its
"information content". Since adaptivity is notoriously difficult to handle in
the analysis of (quantum) cryptographic protocols, this gives us a very
powerful tool: as long as we have enough control over the side information, it
is sufficient to restrict ourselves to non-adaptive attacks.
  We demonstrate the usefulness of this methodology with two examples. The
first is a quantum bit commitment scheme based on 1-bit cut-and-choose. Since
bit commitment implies oblivious transfer (in the quantum setting), and
oblivious transfer is universal for two-party computation, this implies the
universality of 1-bit cut-and-choose, and thus solves the main open problem of
[FKSZZ13]. The second example is a quantum bit commitment scheme proposed in
1993 by Brassard et al. It was originally suggested as an unconditionally
secure scheme, back when this was thought to be possible. We partly restore the
scheme by proving it secure in (a variant of) the bounded quantum storage
model.
  In both examples, the fact that the adversary holds quantum side information
obstructs a direct analysis of the scheme, and we circumvent it by analyzing a
non-adaptive version, which can be done by means of known techniques, and
applying our main result.


title:
Bayesian modelling for binary outcomes in the Regression Discontinuity
  Design

abstract:
  The Regression Discontinuity (RD) design is a quasi-experimental design which
emulates a randomised study by exploiting situations where treatment is
assigned according to a continuous variable as is common in many drug treatment
guidelines. The RD design literature focuses principally on continuous
outcomes. In this paper we exploit the link between the RD design and
instrumental variables to obtain a causal effect estimator, the risk ratio for
the treated (RRT), for the RD design when the outcome is binary. Occasionally
the RRT estimator can give negative lower confindence bounds. In the Bayesian
framework we impose prior constraints that prevent this from happening. This is
novel and cannot be easily reproduced in a frequentist framework. We compare
our estimators to those based on estimating equation and generalized methods of
moments methods. Based on extensive simulations our methods compare favourably
with both methods. We apply our method on a real example to estimate the effect
of statins on the probability of Low-density Lipoprotein (LDL) cholesterol
levels reaching recommended levels.


title:
The Stability of Tidal Equilibrium for Hierarchical Star-Planet-Moon
  Systems

abstract:
  Motivated by the current search for exomoons, this paper considers the
stability of tidal equilibrium for hierarchical three-body systems containing a
star, a planet, and a moon. In this treatment, the energy and angular momentum
budgets include contributions from the planetary orbit, lunar orbit, stellar
spin, planetary spin, and lunar spin. The goal is to determine the optimized
energy state of the system subject to the constraint of constant angular
momentum. Due to the lack of a closed form solution for the full three-body
problem, however, we must use use an approximate description of the orbits. We
first consider the Keplerian limit and find that the critical energy states are
saddle points, rather than minima, so that these hierarchical systems have no
stable tidal equilibrium states. We then generalize the calculation so that the
lunar orbit is described by a time-averaged version of the circular restricted
three-body problem. In this latter case, the critical energy state is a shallow
minimum, so that a tidal equilibrium state exists. In both cases, however, the
lunar orbit for the critical point lies outside the boundary (roughly half the
Hill radius) where (previous) numerical simulations indicate dynamical
instability. These results suggest that star-planet-moon systems have no viable
long-term stable states analogous to those found for two-body systems.


title: Holographic Model of Dual Superconductor for Quark Confinement

abstract:
  We show that a hairy black hole solution can provide a holographically dual
description of quark confinement. There exists a one-parameter sensible metric
which receives the backreaction of matter contents in the holographic action,
where the scalar and gauge field are responsible for the condensation of
chromomagnetic monopoles. This model features a preconfining phase triggered by
second-order monopole condensation and a first-order confinement/deconfinement
phase transition. To confirm the confinement, the quark-antiquark potential is
calculated by probing a QCD string in both phases. At last, contribution from
Kaluza-Klein monopoles in the confining phase is discussed.


title:
Formation of X-ray emitting stationary shocks in magnetized protostellar
  jets

abstract:
  X-ray observations of protostellar jets show evidence of strong shocks
heating the plasma up to temperatures of a few million degrees. In some cases,
the shocked features appear to be stationary. They are interpreted as shock
diamonds. We aim at investigating the physics that guides the formation of
X-ray emitting stationary shocks in protostellar jets, the role of the magnetic
field in determining the location, stability, and detectability in X-rays of
these shocks, and the physical properties of the shocked plasma. We performed a
set of 2.5-dimensional magnetohydrodynamic numerical simulations modelling
supersonic jets ramming into a magnetized medium and explored different
configurations of the magnetic field. The model takes into account the most
relevant physical effects, namely thermal conduction and radiative losses. We
compared the model results with observations, via the emission measure and the
X-ray luminosity synthesized from the simulations. Our model explains the
formation of X-ray emitting stationary shocks in a natural way. The magnetic
field collimates the plasma at the base of the jet and forms there a magnetic
nozzle. After an initial transient, the nozzle leads to the formation of a
shock diamond at its exit which is stationary over the time covered by the
simulations (~ 40 - 60 yr; comparable with time scales of the observations).
The shock generates a point-like X-ray source located close to the base of the
jet with luminosity comparable with that inferred from X-ray observations of
protostellar jets. For the range of parameters explored, the evolution of the
post-shock plasma is dominated by the radiative cooling, whereas the thermal
conduction slightly affects the structure of the shock.


title: Transition to subcritical turbulence in a tokamak plasma

abstract:
  Tokamak turbulence, driven by the ion-temperature gradient and occurring in
the presence of flow shear, is investigated by means of local, ion-scale,
electrostatic gyrokinetic simulations (with both kinetic ions and electrons) of
the conditions in the outer core of the Mega-Ampere Spherical Tokamak (MAST). A
parameter scan in the local values of the ion-temperature gradient and flow
shear is performed. It is demonstrated that the experimentally observed state
is near the stability threshold and that this stability threshold is nonlinear:
sheared turbulence is subcritical, i.e. the system is formally stable to small
perturbations, but, given a large enough initial perturbation, it transitions
to a turbulent state. A scenario for such a transition is proposed and
supported by numerical results: close to threshold, the nonlinear saturated
state and the associated anomalous heat transport are dominated by long-lived
coherent structures, which drift across the domain, have finite amplitudes, but
are not volume filling; as the system is taken away from the threshold into the
more unstable regime, the number of these structures increases until they
overlap and a more conventional chaotic state emerges. Whereas this appears to
represent a new scenario for transition to turbulence in tokamak plasmas, it is
reminiscent of the behaviour of other subcritically turbulent systems, e.g.
pipe flows and Keplerian magnetorotational accretion flows.


title:
Lattice calculation of the pion transition form factor $\pi^0 \to
  \gamma^* \gamma^*$

abstract:
  We calculate the $\pi^0\to \gamma^*\gamma^*$ transition form factor ${\cal
F}_{\pi^0\gamma^*\gamma^*}(q_1^2,q_2^2)$ in lattice QCD with two flavors of
quarks. Our main motivation is to provide the input to calculate the
$\pi^0$-pole contribution to hadronic light-by-light scattering in the muon
$(g-2)$, $a_\mu^{\rm HLbL;\pi^0}$. We therefore focus on the region where both
photons are spacelike up to virtualities of about $1.5~$GeV$^2$, which has so
far not been experimentally accessible. Results are obtained in the continuum
at the physical pion mass by a combined extrapolation. We reproduce the
prediction of the chiral anomaly for real photons with an accuracy of about
$8-9\%$. We also compare to various recently proposed models and find
reasonable agreement for the parameters of some of these models with their
phenomenological values. Finally, we use the parametrization of our lattice
data by these models to calculate $a_\mu^{\rm HLbL;\pi^0}$.


title: Computational Investigation of Microstrip Antennas in Plasma Environment

abstract:
  Microstrip antennas are extensively used in spacecraft systems and other
applications where they encounter a plasma environment. A detailed
computational investigation of change in antenna radiation properties in the
presence of plasma has been presented in this paper. The study shows antenna
properties such as the resonant frequency, return loss, radiation properties
and the different characteristics of the antenna changes when it is surrounded
by plasma. Particular focus of the work is to understand the causes behind
these changes by correlating the complex propagation constant in the plasma
medium, field distribution on the patch and effective dielectric of the antenna
substrate with antenna parameter variations. The study also provides important
insights to explore the possibilities of designing tunable microstrip antenna
where the substrate can be replaced with plasma and important antenna
characteristics can be controlled by varying the plasma density.


title: Suffix arrays with a twist

abstract:
  The suffix array is a classic full-text index, combining effectiveness with
simplicity. We discuss three approaches aiming to improve its efficiency even
more: changes to the navigation, data layout and adding extra data. In short,
we show that $(i)$ how we search for the right interval boundary impacts
significantly the overall search speed, $(ii)$ a B-tree data layout easily wins
over the standard one, $(iii)$ the well-known idea of a lookup table for the
prefixes of the suffixes can be refined with using compression, $(iv)$ caching
prefixes of the suffixes in a helper array can pose a(nother) practical
space-time tradeoff.


title: Magnetic relaxation phenomena in Cu$_2$OSeO$_3$ and phase diagram

abstract:
  We present an investigation of the magnetic field-temperature phase diagram
of Cu$_2$OSeO$_3$ based on DC magnetisation and AC susceptibility measurements
covering a broad frequency range of four orders of magnitude, from very low
frequencies reaching 0.1 Hz up to 1 kHz. The experiments were performed in the
vicinity of $T_C=58.2$ K and around the skyrmion lattice A-phase. At the
borders between the different phases the characteristic relaxation times reach
several milliseconds and the relaxation is non-exponential. Consequently the
borders between the different phases depend on the specific criteria and
frequency used and an unambiguous determination is not possible.


title:
Modelling the cross-spectral variability of the black hole binary MAXI
  J1659-152 with propagating accretion rate fluctuations

abstract:
  The power spectrum of the X-ray fluctuations of accreting black holes often
consists of two broad humps. We quantitatively investigate the hypothesis that
the lower frequency hump orig- inates from variability in a truncated thin
accretion disc, propagating into a large scale-height inner hot flow which, in
turn, itself is the origin of the higher frequency hump. We extend the
propagating mass accretion rate fluctuations model PROPFLUC to accommodate
double hump power spectra in this way. Furthermore, we extend the model to
predict the cross-spectrum between two energy bands in addition to their power
spectra, allowing us to constrain the model using the observed time lags, which
in the model result from both propagation of fluc- tuations from the disc to
the hot flow, and inside the hot flow. We jointly fit soft and hard power
spectrum, and the cross-spectrum between the two bands using this model for 5
Swift X-ray Telescope observations of MAXI J1659-152. The new double hump model
provides a better fit to the data than the old single hump model for most of
our observations. The data show only a small phase lag associated with the low
frequency hump. We demonstrate quan- titatively that this is consistent with
the model. We compare the truncation radius measured from our fits with that
measured purely by spectral fitting and find agreement within a factor of two.
This analysis encompasses the first joint fits of stellar-mass black hole
cross-spectra and power spectra with a single self-consistent physical model.


title: The reverse order law of the $(b, c)$-inverse in rings

abstract:
  We present equivalent conditions of reverse order law for the $(b,
c)$-inverse $(aw)^{(b,c)}=w^{(b,s)}a^{(t,c)}$ to hold in a ring. Also, we study
various mixed-type reverse order laws for the $(b,c)$-inverse. As a
consequence, we get results related to the reverse order law for the inverse
along an element. More general case of reverse order law $(a_1a_2)^{(b_3,
c_3)}=a_2^{(b_2, c_2)}a_1^{(b_1, c_1)}$ is considered too.


title:
Boron-Doped Graphene As Active Electrocatalyst For Oxygen Reduction
  Reaction At A Fuel-Cell Cathode

abstract:
  Boron-doped graphene was reported to be the best non-metal doped graphene
electrocatalyst for the oxygen reduction reaction (ORR) working at an onset
potential of 0.035 V [JACS 136 (2014) 4394]. In the present DFT study,
intermediates and transition structures along the possible reaction pathways
are determined. Both Langmuir-Hinschelwood and Eley-Rideal mechanisms are
discussed. Molecular oxygen binds the positively charged B atom and forms an
open shell end-on dioxygen intermediate. The associative path is favoured with
respect to the dissociative one. The free energy diagrams along the
four-reduction steps are investigated with the methodology by N{\o}rskov and
co. [JPC B 108 (2004) 17886] in both acidic and alkaline conditions. The pH
effect on the stability of the intermediates of reduction is analyzed in terms
of the Pourbaix diagram. At pH = 14 we compute an onset potential value for the
electrochemical ORR of U = 0.05 V, which compares very well with the
experimental value in alkaline conditions.


title: Psychologically inspired planning method for smart relocation task

abstract:
  Behavior planning is known to be one of the basic cognitive functions, which
is essential for any cognitive architecture of any control system used in
robotics. At the same time most of the widespread planning algorithms employed
in those systems are developed using only approaches and models of Artificial
Intelligence and don't take into account numerous results of cognitive
experiments. As a result, there is a strong need for novel methods of behavior
planning suitable for modern cognitive architectures aimed at robot control.
One such method is presented in this work and is studied within a special class
of navigation task called smart relocation task. The method is based on the
hierarchical two-level model of abstraction and knowledge representation, e.g.
symbolic and subsymbolic. On the symbolic level sign world model is used for
knowledge representation and hierarchical planning algorithm, PMA, is utilized
for planning. On the subsymbolic level the task of path planning is considered
and solved as a graph search problem. Interaction between both planners is
examined and inter-level interfaces and feedback loops are described.
Preliminary experimental results are presented.


title: Bell scenarios with communication

abstract:
  Classical and quantum physics provide fundamentally different predictions
about experiments with separate observers that do not communicate, a phenomenon
known as quantum nonlocality. This insight is a key element of our present
understanding of quantum physics, and also enables a number of information
processing protocols with security beyond what is classically attainable.
Relaxing the pivotal assumption of no communication leads to new insights into
the nature quantum correlations, and may enable new applications where security
can be established under less strict assumptions. Here, we study such
relaxations where different forms of communication are allowed. We consider
communication of inputs, outputs, and of a message between the parties. Using
several measures, we study how much communication is required for classical
models to reproduce quantum or general no-signalling correlations, as well as
how quantum models can be augmented with classical communication to reproduce
no-signalling correlations.


title: Structural Emergency Control Paradigm

abstract:
  Power grids normally operate at some stable operating condition where power
supply and demand are balanced. In response to emergency situations, load
shedding is a prevailing approach where local protective devices are activated
to cut a suitable amount of load to quickly rebalance the supply demand and
hopefully stabilize the system. This traditional emergency control results in
interrupted service with severe economic damage to customers. Also, such
control is usually less effective due to the lack of coordination among
protective devices. In this paper, we propose a novel structural emergency
control to render post-fault dynamics from the critical/emergency fault-cleared
state to the stable equilibrium point. This is a new control paradigm that does
not rely on any continuous measurement or load shedding, as in the classical
setup. Instead, the grid is made stable by discretely relocating the
equilibrium point and its stability region such that the system is
consecutively attracted from the fault-cleared state back to the original
equilibrium point. The proposed control is designed by solving linear and
convex optimization problems, making it possibly scalable to large-scale power
grids. Finally, this emergency control scheme can be implemented by exploiting
transmission facilities available on the existing grids.


title:
Learning to do diversity work: A model for continued education of
  program organizers

abstract:
  Physics and physics education in the United States suffer from severe (and,
in some cases, worsening) underrepresentation of Black, Latina/o, and Native
people of all genders and women of all races and ethnicities. This
underrepresentation is a symptom with multiple causes and myriad potential
solutions. In this paper, we describe an approach to addressing the causes of
underrepresentation through physics students' collective and continued
education about racism, sexism, other dimensions of marginalization, as well as
models of allyship and social change. Specifically, we focus on the efforts of
undergraduate students, graduate students, and postdocs who are members of a
student-run diversity-oriented organization in a physics department at a large,
selective, predominantly white university with high research activity. This
group's education was accomplished through quarterly Diversity Workshops. Here
we report on six Diversity Workshops that were co-designed and facilitated by
the authors. We describe the context, motivation, and goals of the workshops,
the theories underlying their design and implementation, and their content. In
addition, we discuss workshop attendance and suggest strategies for maintaining
high attendance in the future. Because the details of our workshops were
tailored to the specific needs and interests of a particular student
organization, our workshop agendas may not be widely applicable beyond our
local context. Therefore, we share our model, design principles, and
facilitation strategies in this paper.


title: Topological complexity of n points on a tree

abstract:
  The topological complexity of a path-connected space $X,$ denoted $TC(X),$
can be thought of as the minimum number of continuous rules needed to describe
how to move from one point in $X$ to another. The space $X$ is often
interpreted as a configuration space in some real-life context. Here, we
consider the case where $X$ is the space of configurations of $n$ points on a
tree $\Gamma.$ We will be interested in two such configuration spaces. In the,
first, denoted $C^n(\Gamma),$ the points are distinguishable, while in the
second, $UC^n(\Gamma),$ the points are indistinguishable. We determine
$TC(UC^n(\Gamma))$ for any tree $\Gamma$ and many values of $n,$ and
consequently determine $TC(C^n(\Gamma))$ for the same values of $n$ (provided
the configuration spaces are path-connected).


title: Android Malware Detection Using Parallel Machine Learning Classifiers

abstract:
  Mobile malware has continued to grow at an alarming rate despite on-going
efforts towards mitigating the problem. This has been particularly noticeable
on Android due to its being an open platform that has subsequently overtaken
other platforms in the share of the mobile smart devices market. Hence,
incentivizing a new wave of emerging Android malware sophisticated enough to
evade most common detection methods. This paper proposes and investigates a
parallel machine learning based classification approach for early detection of
Android malware. Using real malware samples and benign applications, a
composite classification model is developed from parallel combination of
heterogeneous classifiers. The empirical evaluation of the model under
different combination schemes demonstrates its efficacy and potential to
improve detection accuracy. More importantly, by utilizing several classifiers
with diverse characteristics, their strengths can be harnessed not only for
enhanced Android malware detection but also quicker white box analysis by means
of the more interpretable constituent classifiers.


title:
Operational criterion for controlled dense coding with non-trivial
  tripartite entangled states

abstract:
  In this paper, we provide an operational criterion for controlled dense
coding with a general class of three-qubit partially entangled states. A
general three-qubit pure entangled state can be classified into two
inequivalent classes according to their genuine tripartite entanglement. We
claim that if a three-qubit state shows entanglement characteristic similar to
$GHZ$-class then such non-trivial tripartite states are useful in {\it
controlled dense coding} whereas states belonging to $W$-class are not useful
for that. We start with a particular class of non-trivial partially entangled
states belonging to $GHZ$-class and show that they are effective in controlled
dense coding. Then we cite several other examples of different types of
tripartite entangled states to support our conjecture.


title:
Online Trajectory Segmentation and Summary With Applications to
  Visualization and Retrieval

abstract:
  Trajectory segmentation is the process of subdividing a trajectory into parts
either by grouping points similar with respect to some measure of interest, or
by minimizing a global objective function. Here we present a novel online
algorithm for segmentation and summary, based on point density along the
trajectory, and based on the nature of the naturally occurring structure of
intermittent bouts of locomotive and local activity. We show an application to
visualization of trajectory datasets, and discuss the use of the summary as an
index allowing efficient queries which are otherwise impossible or
computationally expensive, over very large datasets.


title:
A versatile and light-weight slow control system for small-scale
  applications

abstract:
  We present an open source slow control system for small and medium scale
projects. Thanks to its modular and flexible design, where the various
instruments are read and controlled by independent plugins, Doberman (Detector
OBsERving and Monitoring ApplicatioN) can be quickly adapted for many
applications, also making use of existing code or proprietary components. The
system uses a SQL database to store the data from the instruments and provides
an online application to display and browse through the data. It allows the
modification of device settings while the program is running and features a
protocol to handle exceptions, including the automated distribution of alarm
messages. We present two case studies from astroparticle physics, on which
Doberman is successfully deployed: a low-background screening facility
installed in a remote underground laboratory and a detector R&D platform using
cryogenic liquid xenon.


title:
Spiral magnetic order and topological superconductivity in a chain of
  magnetic adatoms on a two-dimensional superconductor

abstract:
  We study the magnetic and electronic phases of a 1D magnetic adatom chain on
a 2D superconductor. In particular, we confirm the existence of a
`self-organized' 1D topologically non-trivial superconducting phase within the
set of subgap Yu-Shiba-Rusinov (YSR) states formed along the magnetic chain.
This phase is stabilized by incommensurate spiral correlations within the
magnetic chain that arise from the competition between short-range
ferromagnetic and long-range antiferromagnetic electron-induced exchange
interactions, similar to a recent study for a 3D superconductor [M. Schecter et
al. Phys. Rev. B 93, 140503(R) 2016]. The exchange interaction along diagonal
directions are also considered and found to display behavior similar to a 1D
substrate when close to half filling. We show that the topological phase
diagram is robust against local superconducting order parameter suppression and
weak substrate spin-orbit coupling. Lastly, we study the effect of a direct
ferromagnetic exchange coupling between the adatoms, and find the region of
spiral order in the phase diagram to be significantly enlarged in a wide range
of the direct exchange coupling.


title: Quantum walk on a cylinder

abstract:
  We consider the 2D alternate quantum walk on a cylinder. We concentrate on
the study of the motion along the open dimension, in the spirit of looking at
the closed coordinate as a small or "hidden" extra dimension. If one starts
from localized initial conditions on the lattice, the dynamics of the quantum
walk that is obtained after tracing out the small dimension shows the
contribution of several components, which can be understood from the study of
the dispersion relations for this problem. In fact, these components originate
from the contribution of the possible values of the quasi-momentum in the
closed dimension. In the continuous space-time limit, the different components
manifest as a set of Dirac equations, with each quasi-momentum providing the
value of the corresponding mass. We briefly discuss the possible link of these
ideas to the simulation of high energy physical theories that include extra
dimensions. Finally, entanglement between the coin and spatial degrees of
freedom is studied, showing that the entanglement entropy clearly overcomes the
value reached with only one spatial dimension.


title: Counting matchings with k unmatched vertices in planar graphs

abstract:
  We consider the problem of counting matchings in planar graphs. While perfect
matchings in planar graphs can be counted by a classical polynomial-time
algorithm, the problem of counting all matchings (possibly containing unmatched
vertices, also known as defects) is known to be #P-complete on planar graphs.
To interpolate between the hard case of counting matchings and the easy case of
counting perfect matchings, we study the parameterized problem of counting
matchings with exactly k unmatched vertices in a planar graph G, on input G and
k. This setting has a natural interpretation in statistical physics, and it is
a special case of counting perfect matchings in k-apex graphs (graphs that can
be turned planar by removing at most k vertices).
  Starting from a recent #W[1]-hardness proof for counting perfect matchings on
k-apex graphs, we obtain that counting matchings with k unmatched vertices in
planar graphs is #W[1]-hard. In contrast, given a plane graph G with s
distinguished faces, there is an $O(2^s \cdot n^3)$ time algorithm for counting
those matchings with k unmatched vertices such that all unmatched vertices lie
on the distinguished faces. This implies an $f(k,s)\cdot n^{O(1)}$ time
algorithm for counting perfect matchings in k-apex graphs whose apex
neighborhood is covered by s faces.


title: Loss-tolerant quantum secure positioning with weak laser sources

abstract:
  Quantum position verification (QPV) is the art of verifying the geographical
location of an untrusted party. Recently, it has been shown that the widely
studied Bennett & Brassard 1984 (BB84) QPV protocol is insecure after the 3 dB
loss point assuming local operations and classical communication (LOCC)
adversaries. Here, we propose a time-reversed entanglement swapping QPV
protocol (based on measurement-device-independent quantum cryptography) that is
highly robust against quantum channel loss. First, assuming ideal qubit
sources, we show that the protocol is secure against LOCC adversaries for any
quantum channel loss, thereby overcoming the 3 dB loss limit. Then, we analyze
the security of the protocol in a more practical setting involving weak laser
sources and linear optics. In this setting, we find that the security only
degrades by an additive constant and the protocol is able to verify positions
up to 47 dB channel loss.


title: Convolutional Neural Networks Analyzed via Convolutional Sparse Coding

abstract:
  Convolutional neural networks (CNN) have led to many state-of-the-art results
spanning through various fields. However, a clear and profound theoretical
understanding of the forward pass, the core algorithm of CNN, is still lacking.
In parallel, within the wide field of sparse approximation, Convolutional
Sparse Coding (CSC) has gained increasing attention in recent years. A
theoretical study of this model was recently conducted, establishing it as a
reliable and stable alternative to the commonly practiced patch-based
processing. Herein, we propose a novel multi-layer model, ML-CSC, in which
signals are assumed to emerge from a cascade of CSC layers. This is shown to be
tightly connected to CNN, so much so that the forward pass of the CNN is in
fact the thresholding pursuit serving the ML-CSC model. This connection brings
a fresh view to CNN, as we are able to attribute to this architecture
theoretical claims such as uniqueness of the representations throughout the
network, and their stable estimation, all guaranteed under simple local
sparsity conditions. Lastly, identifying the weaknesses in the above pursuit
scheme, we propose an alternative to the forward pass, which is connected to
deconvolutional, recurrent and residual networks, and has better theoretical
guarantees.


title: Nearly neighbourly families of standard boxes

abstract:
  It is demonstrated that each nearly neighbourly family of standard boxes in
$\mathbb{R}^3$ has at most 12 elements. A combinatorial classification of all
such families that have exactly 12 elements is given. All families satisfying
an extra property called incompressibility are described. Compressible families
are discussed briefly.


title:
Calorie Counter: RGB-Depth Visual Estimation of Energy Expenditure at
  Home

abstract:
  We present a new framework for vision-based estimation of calorific
expenditure from RGB-D data - the first that is validated on physical gas
exchange measurements and applied to daily living scenarios. Deriving a
person's energy expenditure from sensors is an important tool in tracking
physical activity levels for health and lifestyle monitoring. Most existing
methods use metabolic lookup tables (METs) for a manual estimate or systems
with inertial sensors which ultimately require users to wear devices. In
contrast, the proposed pose-invariant and individual-independent vision
framework allows for a remote estimation of calorific expenditure. We
introduce, and evaluate our approach on, a new dataset called SPHERE-calorie,
for which visual estimates can be compared against simultaneously obtained,
indirect calorimetry measures based on gas exchange. % based on per breath gas
exchange. We conclude from our experiments that the proposed vision pipeline is
suitable for home monitoring in a controlled environment, with calorific
expenditure estimates above accuracy levels of commonly used manual estimations
via METs. With the dataset released, our work establishes a baseline for future
research for this little-explored area of computer vision.


title:
Interrogating the superconductor Ca10(Pt4As8)(Fe2-xPtxAs2)5
  Layer-by-layer

abstract:
  Ever since the discovery of high-Tc superconductivity in layered cuprates,
the roles that individual layers play have been debated, due to difficulty in
layer-by-layer characterization. While there is similar challenge in many
Fe-based layered superconductors, the newly-discovered Ca10(Pt4As8)(Fe2As2)5
provides opportunities to explore superconductivity layer by layer, because it
contains both superconducting building blocks (Fe2As2 layers) and intermediate
Pt4As8 layers. Cleaving a single crystal under ultra-high vacuum results in
multiple terminations: an ordered Pt4As8 layer, two reconstructed Ca layers on
the top of a Pt4As8 layer, and disordered Ca layer on the top of Fe2As2 layer.
The electronic properties of individual layers are studied using scanning
tunneling microscopy/spectroscopy (STM/S), which reveals different spectra for
each surface. Remarkably superconducting coherence peaks are seen only on the
ordered Ca/Pt4As8 layer. Our results indicate that an ordered structure with
proper charge balance is required in order to preserve superconductivity.


title: Rigid divisors on surfaces

abstract:
  We study effective divisors $D$ on surfaces with $H^0(\mathcal O_D)=k$ and
$H^1(\mathcal O_D)=H^0(\mathcal O_D(D))=0$. We give a numerical criterion for
such divisors, following a general investigation of negativity, rigidity and
connectivity properties. Examples include exceptional loci of rational
singularities, and spherelike divisors.


title: Bridgeland Stability Conditions on Fano Threefolds

abstract:
  We show the existence of Bridgeland stability conditions on all Fano
threefolds, by proving a modified version of a conjecture by Bayer, Toda, and
the second author. The key technical ingredient is a strong Bogomolov
inequality, proved recently by Chunyi Li. Additionally, we prove the original
conjecture for some toric threefolds by using the toric Frobenius morphism.


title: Analysis of a Frequency-Hopping Millimeter-Wave Cellular Uplink

abstract:
  Fifth-generation (5G) cellular networks are expected to exhibit at least
three primary physical-layer differences relative to fourth-generation ones:
millimeter-wave propagation, massive antenna arrays, and densification of base
stations. As in fourth-generation systems, such as LTE, 5G systems are likely
to continue to use single-carrier frequency division multiple-access (SC-FDMA)
on the uplink due to its advantageous peak-to-average power ratio. Moreover, 5G
systems are likely to use frequency hopping on the uplink to help randomize
interference and provide diversity against frequency-selective fading. In this
paper, the implications of these and other physical-layer features on uplink
performance are assessed using a novel millimeter-wave propagation model
featuring distance-dependent parameters that characterize the path-loss,
shadowing, and fading. The analysis proceeds by first fixing the location of
the mobile devices and finding the performance conditioned on the topology. The
spatially averaged performance is then found by averaging with respect to the
location of the mobile devices. The analysis allows for the use of actual
base-station topologies and the propagation model can leverage empirical
millimeter-wave measurements. The benefits of base-station densification,
highly directional sectorization, frequency hopping, a large available
bandwidth, and a high code rate are illustrated. The minor importance of
fractional power control is shown.


title: Edge currents in frustrated Josephson junction ladders

abstract:
  We present a numerical study of quasi-1D frustrated Josephson junction
ladders with diagonal couplings and open boundary conditions, in the large
capacitance limit. We derive a correspondence between the energy of this
Josephson junction ladder and the expectation value of the Hamiltonian of an
analogous tight-binding model, and show how the overall superconducting state
of the chain is equivalent to the minimum energy state of the tight-binding
model in the subspace of one-particle states with uniform density. To satisfy
the constraint of uniform density, the superconducting state of the ladder is
written as a linear combination of the allowed k-states of the tight-binding
model with open boundaries. Above a critical value of the parameter t (ratio
between the intra-rung and inter-rung Josephson couplings), the ladder
spontaneously develop currents at the edges which spread to the bulk as t is
increased until complete coverage is reached. Above a certain value of t, which
varies with ladder size (t = 1 for an infinite-sized ladder), the edge currents
are destroyed. The value t = 1 corresponds, in the tight-binding model, to the
opening of a gap between two bands. We argue that the disappearance of the edge
currents with this gap opening is not coincidental, and that this points to a
topological origin for these edge current states.


title:
A short note on a class of statistics for estimation of the Hurst index
  of fractional Brownian motion

abstract:
  We propose some class of statistics suitable for estimation of the Hurst
index of the fractional Brownian motion based on the second order increments of
an observed discrete trajectory.


title:
Collective benefits in traffic during mega events via the use of
  information technologies

abstract:
  Information technologies today can inform each of us about the best
alternatives for shortest paths from origins to destinations, but they do not
contain incentives or alternatives that manage the information efficiently to
get collective benefits. To obtain such benefits, we need to have not only good
estimates of how the traffic is formed but also to have target strategies to
reduce enough vehicles from the best possible roads in a feasible way. The
opportunity is that during large events the traffic inconveniences in large
cities are unusually high, yet temporary, and the entire population may be more
willing to adopt collective recommendations for social good. In this paper, we
integrate for the first time big data resources to quantify the impact of
events and propose target strategies for collective good at urban scale. In the
context of the Olympic Games in Rio de Janeiro, we first predict the expected
increase in traffic. To that end, we integrate data from: mobile phones,
Airbnb, Waze, and transit information, with game schedules and information of
venues. Next, we evaluate the impact of the Olympic Games to the travel of
commuters, and propose different route choice scenarios during the peak hours.
Moreover, we gather information on the trips that contribute the most to the
global congestion and that could be redirected from vehicles to transit.
Interestingly, we show that (i) following new route alternatives during the
event with individual shortest path can save more collective travel time than
keeping the routine routes, uncovering the positive value of information
technologies during events; (ii) with only a small proportion of people
selected from specific areas switching from driving to public transport, the
collective travel time can be reduced to a great extent. Results are presented
on-line for the evaluation of the public and policy makers.


title: Condensation of Thresholds in Multimode Microlasers

abstract:
  We show from ab initio laser theory that by choosing an appropriate spatial
pump profile, many different spatial modes of a typical microlaser can be
turned on at the same pump energy, substantially increasing the number, N, of
simultaneous lasing modes. The optimal pump profile can be obtained simply from
knowledge of the space-dependent saturated gain profile when the system is
uniformly pumped up to the Nth modal threshold. We test this general result by
applying it to a two-dimensional diffusive random laser and a microdisk laser.
Achieving highly multimode lasing at reasonable pump powers is useful for
reducing the spatial coherence of laser sources, making them suitable for use
in speckle-free imaging and other applications.


title:
Is Bonferroni correction more sensitive than Random Field Theory for
  most fMRI studies?

abstract:
  Random Field Theory has been used in the fMRI literature to address the
multiple comparisons problem. The method provides an analytical solution for
the computation of precise p-values when its assumptions are met. When its
assumptions are not met the thresholds generated by Random Field Theory can be
more conservative than Bonferroni corrections, which are arguably too stringent
for use in fMRI. As this has been well documented theoretically it is
surprising that a majority of current studies (~80%) would not meet the
assumptions of Random Field Theory and therefore would have reduced
sensitivity. Specifically most data is not smooth enough to meet the good
lattice assumption. Current studies smooth data on average by twice the voxel
size which is rarely sufficient to meet the good lattice assumption. The amount
of smoothing required for Random Field Theory to produce accurate p-values
increases with image resolution and decreases with degrees of freedom. There is
no rule of thumb that is valid for all study designs but for typical data (3mm
resolution, and greater than 20 subjects) residual smoothness with FWHM = 4
times voxel size should produce valid results. However, it should be stressed
that for higher spatial resolution and lower degrees of freedom the critical
smoothness required will increase sharply. This implies that researchers should
carefully choose appropriate smoothing kernels. This can be facilitated by the
simulations we provide that identify the critical smoothness at which the
application of RFT becomes appropriate. For some applications such as
presurgical mapping or, imaging of small structures, probing the
laminar/columnar structure of the cortex these smoothness requirements may be
too great to preserve spatial structure. As such, this study suggests
developments are needed in Random Field Theory to fully exploit the resolution
of modern neuroimaging.


title: Diagnostic Prediction Using Discomfort Drawings with IBTM

abstract:
  In this paper, we explore the possibility to apply machine learning to make
diagnostic predictions using discomfort drawings. A discomfort drawing is an
intuitive way for patients to express discomfort and pain related symptoms.
These drawings have proven to be an effective method to collect patient data
and make diagnostic decisions in real-life practice. A dataset from real-world
patient cases is collected for which medical experts provide diagnostic labels.
Next, we use a factorized multimodal topic model, Inter-Battery Topic Model
(IBTM), to train a system that can make diagnostic predictions given an unseen
discomfort drawing. The number of output diagnostic labels is determined by
using mean-shift clustering on the discomfort drawing. Experimental results
show reasonable predictions of diagnostic labels given an unseen discomfort
drawing. Additionally, we generate synthetic discomfort drawings with IBTM
given a diagnostic label, which results in typical cases of symptoms. The
positive result indicates a significant potential of machine learning to be
used for parts of the pain diagnostic process and to be a decision support
system for physicians and other health care personnel.


title:
The Role of Multilevel Landau-Zener Interference in Extreme Harmonic
  Generation

abstract:
  Motivated by the observation of multiphoton electric dipole spin resonance
processes in InAs nanowires, we theoretically study the transport dynamics of a
periodically driven five-level system, modeling the level structure of a
two-electron double quantum dot. We show that the observed multiphoton
resonances, which are dominant near interdot charge transitions, are due to
multilevel Landau-Zener-Stuckelberg-Majorana interference. Here a third energy
level serves as a shuttle that transfers population between the two resonant
spin states. By numerically integrating the master equation we replicate the
main features observed in the experiments: multiphoton resonances (as large as
8 photons), a robust odd-even dependence, and oscillations in the electric
dipole spin resonance signal as a function of energy level detuning.