title:
Hochschild cohomology versus the Jacobian ring, and the Torelli theorem
  for cubic fourfolds

abstract:
  The Jacobian ring J(X) of a smooth hypersurface determines its isomorphism
type. This has been used by Donagi and others to prove the generic global
Torelli theorem for hypersurfaces in many cases. In Voisin's original proof of
the global Torelli theorem for smooth cubic fourfolds the Jacobian ring does
not intervene. In this paper we present a proof of the global Torelli theorem
for cubic fourfolds that relies on the Jacobian ring and the (derived) global
Torelli theorem for K3 surfaces. It emphasizes, once again, the relation
between K3 surfaces and smooth cubic fourfolds. More generally, for a variant
of Hochschild cohomology of Kuznetsov's category (together with the degree
shift functor) associated with an arbitrary smooth hypersurface we construct a
graded ring homomorphism from the Jacobian ring to it, which is shown to be
bijective whenever Kuznetsov's category is a Calabi-Yau category.


title:
Emission from quantum-dot high- microcavities: transition from
  spontaneous emission to lasing and the effects of superradiant emitter
  coupling

abstract:
  Measured and calculated results are presented on the emission properties of a
new class of emitters operating in the cavity quantum electrodynamics regime.
The structures are based on high-finesse GaAs/AlAs micropillar cavities, each
with an active medium consisting of a layer of InGaAs quantum dots and
distinguishing feature of having substantial fraction of spontaneous emission
channeled into one cavity mode (high-beta factor). This paper shows that the
usual criterion for lasing with a conventional (low-beta factor) cavity, a
sharp nonlinearity in an input-output curve accompanied by noticeable linewidth
narrowing, has to be reinforced by the equal-time second-order photon
autocorrelation function for confirming lasing. It will also show that the
equal-time second-order photon autocorrelation function is useful for
recognizing superradiance, a manifestation of the correlations possible in
high- microcavities operating with quantum dots. In terms of consolidating the
collected data and identifying the physics underlying laser action, both theory
and experiment suggest a sole dependence on intracavity photon number. Evidence
for this comes from all our measured and calculated data on emission coherence
and fluctuation, for devices ranging from LEDs and cavity-enhanced LEDs to
lasers, lying on the same two curves: one for linewidth narrowing versus
intracavity photon number and the other for g(2)(0) versus intracavity photon
number.


title: Exclusive production of two and four pions in proton-proton scattering

abstract:
  We consider exclusive $pp \to pp \pi^{+} \pi^{-}$ and $pp \to pp \pi^{+}
\pi^{-}\pi^{+} \pi^{-}$ reactions at high energies. The calculation is based on
a tensor pomeron model and the amplitudes for the processes are formulated in
an effective field-theoretic approach. In the case of $pp \to pp \pi^{+}
\pi^{-}$ process we consider both diffractive and photoproduction mechanisms
and we include the non-resonant $\pi^{+}\pi^{-}$ continuum and the resonance
$f_{0}(500)$, $f_{0}(980)$, $f_{2}(1270)$, $\rho(770)$ contributions. We
discuss how two pomerons couple to tensor meson $f_{2}(1270)$ and the
interference effects of resonance and dipion continuum. We find that the
relative contribution of resonances $\rho(770)$, $f_2(1270)$ and dipion
continuum strongly depends on the cut on proton transverse momenta. In the case
of exclusive central $4 \pi$ production we include the contribution via the
intermediate $\sigma\sigma$ and $\rho\rho$ states. For both processes the
theoretical results have been compared with the experimental data and
predictions for planned or being carried out experiments (e.g. STAR,
ATLAS-ALFA) are presented.


title: Effective Field Theory and Unitarity in Vector Boson Scattering

abstract:
  Weak vector boson scattering at high energies will be one of the key
measurements in current and upcoming LHC runs. It is most sensitive to any new
physics associated with electroweak symmetry breaking. However, a conventional
EFT analysis will fail at high energies. To address this problem, we present a
parameter-free prescription valid for arbitrary perturbative and
non-perturbative models: the T-matrix unitarization. We describe its
implementation as an asymptotically consistent reference model matched to the
low-energy effective theory. We show examples of typical observables of
vector-boson scattering at the LHC in our unitarized framework. For many
strongly-coupled models like composite Higgs models, dimension-8 operators
might be actually the leading operators. In addition to those longitudinal and
transversal dimension eight EFT operators, the effects of generic tensor and
scalar resonances within simplified models are considered.


title: Counter-diabatic vortex pump in spinor Bose-Einstein condensates

abstract:
  Topological phase imprinting is a well-established technique for
deterministic vortex creation in spinor Bose-Einstein condensates of alkali
metal atoms. It was recently shown that counter-diabatic quantum control may
accelerate vortex creation in comparison to the standard adiabatic protocol and
suppress the atom loss due to nonadiabatic transitions. Here we apply this
technique, assisted by an optical plug, for vortex pumping to theoretically
show that sequential phase imprinting up to 20 cycles generates a vortex with a
very large winding number. Our method significantly increases the fidelity of
the pump for rapid pumping compared to the case without the counter-diabatic
control, leading to the highest angular momentum per particle reported to date
for the vortex pump. Our studies are based on numerical integration of the
three-dimensional multi-component Gross-Pitaevskii equation which conveniently
yields the density profiles, phase profiles, angular momentum, and other
physically important quantities of the spin-1 system. Our results motivate the
experimental realization of the vortex pump and studies of the rich physics it
involves.


title:
Looking into Analytical Approximations for Three-flavor Neutrino
  Oscillation Probabilities in Matter

abstract:
  Motivated by tremendous progress in neutrino oscillation experiments, we
derive a new set of simple and compact formulas for three-flavor neutrino
oscillation probabilities in matter of a constant density. A useful definition
of the $\eta$-gauge neutrino mass-squared difference $\Delta^{}_* \equiv \eta
\Delta^{}_{31} + (1-\eta) \Delta^{}_{32}$ is introduced, where $\Delta^{}_{ji}
\equiv m^2_j - m^2_i$ for $ji = 21, 31, 32$ are the ordinary neutrino
mass-squared differences and $0 \leq \eta \leq 1$ is a real and positive
parameter. Expanding neutrino oscillation probabilities in terms of $\alpha
\equiv \Delta^{}_{21}/\Delta^{}_*$, we demonstrate that the analytical formulas
can be remarkably simplified for $\eta = \cos^2 \theta^{}_{12}$, with
$\theta_{12}^{}$ being the solar mixing angle. As a by-product, the mapping
from neutrino oscillation parameters in vacuum to their counterparts in matter
is obtained at the order of ${\cal O}(\alpha^2)$. Finally, we show that our
approximate formulas are not only valid for an arbitrary neutrino energy and
any baseline length, but also still maintaining a high level of accuracy.


title: Mind Control as a Guide for the Mind

abstract:
  The human brain is a complex network that supports mental function. The
nascent field of network neuroscience applies tools from mathematics to
neuroimaging data in the hopes of shedding light on cognitive function. A
critical question arising from these empirical studies is how to modulate a
human brain network to treat cognitive deficits or enhance mental abilities.
While historically a number of tools have been employed to modulate mental
states (such as cognitive behavioral therapy and brain stimulation),
theoretical frameworks to guide these interventions - and to optimize them for
clinical use - are fundamentally lacking. One promising and as-yet
underexplored approach lies in a sub-discipline of engineering known as network
control theory. Here, we posit that network control fundamentally relates to
mind control, and that this relationship highlights important areas for future
empirical research and opportunities to translate knowledge in practical
domains. We clarify the conceptual intersection between neuroanatomy,
cognition, and control engineering in the context of network neuroscience.
Finally, we discuss the challenges, ethics, and promises of mind control.


title:
Asymptotic Intermediate Efficiency of the Chi-square and Likelihood
  Ratio Goodness of Fit Tests

abstract:
  The problem of testing the goodness of fit of an absolutely continuous
distribution to a set of observations grouped into equal probability intervals,
against to a family of sequences of alternatives approaching the hypothesis is
considered. We focus our study to the asymptotic intermediate efficiency (AIE)
due to Inglot (1999) of the chi-squared and log-likelihood ratio tests. It is
assumed that the number of groups increases together with the number of
observations.


title:
Ar+-ion Bombardment of TiO2 Nanotubes Creates Co-catalytic Effect for
  Photocatalytic Open Circuit Hydrogen Evolution

abstract:
  In the present work, extended Argon ion bombardment was used to modify
anatase TiO2 nanotube (NTs) layers. In situ X-ray photoelectron spectroscopy
revealed a high content of sub-oxide formed (Ti3+, Ti2+ states) in the nanotube
layers. These samples were tested for their ability to show open-circuit
photocatalytic hydrogen evolution. We found for UV (cw laser 325nm)
illumination as well as for AM1.5 conditions, a strongly enhanced H2 evolution
activity in absence of the usual noble metal-nanoparticle decoration. We
conclude therefore that these sub-oxide states can play an important role in
the activation of TiO2 nanotubes - namely as a H2 evolution co-catalyst.


title:
Quiver representations over a quasi-Frobenius ring and
  Gorenstein-projective modules

abstract:
  We consider a finite acyclic quiver $\mathcal{Q}$ and a quasi-Frobenius ring
$R$. We endow the category of quiver representations over $R$ with a model
structure, whose homotopy category is equivalent to the stable category of
Gorenstein-projective modules over the path algebra $R\mathcal{Q}$.
  As an application, we then characterize Gorenstein-projective
$R\mathcal{Q}$-modules in terms of the corresponding quiver
$R$-representations; this generalizes a result obtained by Luo-Zhang to the
case of not necessarily finitely generated $R\mathcal{Q}$-modules, and
partially recover results due to Enochs-Estrada-Garc\'ia Rozas, and to
Eshraghi-Hafezi-Salarian. Our approach to the problem is completely different
since the proofs mainly rely on model category theory.


title:
Multiple-quantum transitions and charge-induced decoherence of donor
  nuclear spins in silicon

abstract:
  We study single- and multi-quantum transitions of the nuclear spins of
ionized arsenic donors in silicon and find quadrupolar effects on the coherence
times, which we link to fluctuating electrical field gradients present after
the application of light and bias voltage pulses. To determine the coherence
times of superpositions of all orders in the 4-dimensional Hilbert space, we
use a phase-cycling technique and find that, when electrical effects were
allowed to decay, these times scale as expected for a field-like decoherence
mechanism such as the interaction with surrounding $^{29}$Si nuclear spins.


title:
On the Coupling of Fields and Particles in Accelerator and Plasma
  Physics

abstract:
  In accelerator and plasma physics it is accepted that there is no need to
solve the dynamical equations for particles in covariant form, i.e. by using
the coordinate-independent proper time to parameterize particle world-lines in
space-time: to describe dynamics in the laboratory frame, there is no need to
use the laws of relativistic kinematics. It is sufficient to account for the
relativistic dependence of particles momenta on the velocity in the second
Newton's law. Then, the coupling of fields and particles is based on the use of
result from particle dynamics treated according to Newton's laws in terms of
the relativistic three-momentum and on the use of Maxwell's equations in
standard form. Previously, we argued that this is a misconception. Here we
describe in detail how to calculate the coupling between fields and particles
in a correct way and how to develop a new algorithm for a particle tracking
code in agreement with the use of Maxwell's equations in their standard form.
Advanced textbooks on classical electrodynamics correctly tell us that
Maxwell's equations in standard form in the laboratory frame and charged
particles are coupled by introducing particles trajectories as projections of
particles world-lines onto coordinates of the laboratory frame and then by
using the laboratory time to parameterize the trajectory curves. We show a
difference between conventional and covariant particle tracking results in the
laboratory frame. This essential point has never received attention in the
physical community. Only the solution of the dynamical equations in covariant
form gives the correct coupling between field equations in standard form and
particles trajectories in the laboratory frame. Previous theoretical and
simulation results in accelerator and plasma physics should be re-examined in
the light of the pointed difference between conventional and covariant particle
tracking.


title:
Analysis of antenna position measurements and weather station network
  data during the ALMA Long Baseline Campaign of 2015

abstract:
  In a radio interferometer, the determination of geometrical antenna positions
relies on accurate calibration of the dry and wet delay of the atmosphere above
each antenna. For the Atacama Large Millimeter/Submillimeter Array (ALMA),
which has baseline lengths up to 16 kilometers, the geography of the site
forces the height above mean sea level of the more distant antenna pads to be
significantly lower than the central array. Thus, both the ground level
meteorological values and the total water column can be quite different between
antennas in the extended configurations. During 2015, a network of six
additional weather stations was installed to monitor pressure, temperature,
relative humidity and wind velocity, in order to test whether inclusion of
these parameters could improve the repeatability of antenna position
determinations in these configurations. We present an analysis of the data
obtained during the ALMA Long Baseline Campaign of Oct. through Nov. 2015. The
repeatability of antenna position measurements typically degrades as a function
of antenna distance. Also, the scatter is more than three times worse in the
vertical direction than in the local tangent plane, suggesting that a
systematic effect is limiting the measurements. So far we have explored
correcting the delay model for deviations from hydrostatic equilibrium in the
measured air pressure and separating the partial pressure of water from the
total pressure using water vapor radiometer (WVR) data. Correcting for these
combined effects still does not provide a good match to the residual position
errors in the vertical direction. One hypothesis is that the current model of
water vapor may be too simple to fully remove the day-to-day variations in the
wet delay. We describe possible avenues of improvement, including measuring and
applying more accurate values of the sky coupling efficiency of the WVRs.


title:
Scale Stain: Multi-Resolution Feature Enhancement in Pathology
  Visualization

abstract:
  Digital whole-slide images of pathological tissue samples have recently
become feasible for use within routine diagnostic practice. These gigapixel
sized images enable pathologists to perform reviews using computer workstations
instead of microscopes. Existing workstations visualize scanned images by
providing a zoomable image space that reproduces the capabilities of the
microscope. This paper presents a novel visualization approach that enables
filtering of the scale-space according to color preference. The visualization
method reveals diagnostically important patterns that are otherwise not
visible. The paper demonstrates how this approach has been implemented into a
fully functional prototype that lets the user navigate the visualization
parameter space in real time. The prototype was evaluated for two common
clinical tasks with eight pathologists in a within-subjects study. The data
reveal that task efficiency increased by 15% using the prototype, with
maintained accuracy. By analyzing behavioral strategies, it was possible to
conclude that efficiency gain was caused by a reduction of the panning needed
to perform systematic search of the images. The prototype system was well
received by the pathologists who did not detect any risks that would hinder use
in clinical routine.


title:
Decision Support for Increasing the Efficiency of Crowdsourced Software
  Development

abstract:
  Crowdsourced software development (CSD) offers a series of specified tasks to
a large crowd of trustworthy software workers. Topcoder is a leading platform
to manage the whole process of CSD. While increasingly accepted as a realistic
option for software development, preliminary analysis on Topcoder's software
crowd worker behaviors reveals an alarming task-quitting rate of 82.9%. In
addition, a substantial number of tasks do not receive any successful
submission.
  In this paper, we report about a methodology to improve the efficiency of
CSD. We apply massive data analytics and machine leaning to (i) perform
comparative analysis on alternative technique analysis to predict likelihood of
winners and quitters for each task, (ii) significantly reduce the amount of
non-succeeding development effort in registered but inappropriate tasks, (iii)
identify and rank the most qualified registered workers for each task, and (iv)
provide reliable prediction of tasks risky to get any successful submission.
  Our results and analysis show that Random Forest (RF) based predictive
technique performs best among the alternative techniques studied. Applying RF,
the tasks recommended to workers can reduce the amount of non-succeeding
development effort to a great extent. On average, over a period of 30 days, the
savings are 3.5 and 4.6 person-days per registered tasks for experienced resp.
unexperienced workers. For the task-related recommendations of workers, we can
accurately recommend at least 1 actual winner in the top ranked workers,
particularly 94.07% of the time among the top-2 recommended workers for each
task. Finally, we can predict, with more than 80% F-measure, the tasks likely
not getting any submission, thus triggering timely corrective actions from CSD
platforms or task requesters.


title: Property $P_{naive}$ for acylindrically hyperbolic groups

abstract:
  We prove that every acylindrically hyperbolic group that has no non-trivial
finite normal subgroup satisfies a strong ping pong property, the $P_{naive}$
property: for any finite collection of elements $h_1, \dots, h_k$, there exists
another element $\gamma\neq 1$ such that for all $i$, $\langle h_i, \gamma
\rangle = \langle h_i \rangle* \langle \gamma \rangle$. We also obtain that if
a collection of subgroups $H_1, \dots, H_k$ is a hyperbolically embedded
collection, then there is $\gamma \neq 1$ such that for all $i$, $\langle H_i,
\gamma \rangle = H_i * \langle \gamma \rangle$.


title:
M-theory in the Omega-background and 5-dimensional non-commutative gauge
  theory

abstract:
  The $\Omega$-background is defined for supergravity, and a very general class
of such backgrounds is constructed for 11-dimensional supergravity.
11-dimensional supergravity in a certain $\Omega$-background is shown to be
equivalent to a 5-dimensional non-commutative gauge theory of Chern-Simons
type. M2 and M5 branes are expressed as 1 and 2-dimensional extended objects in
the 5-dimensional gauge theory. This 5-dimensional gauge theory is shown to
admit a consistent quantization with two coupling constants, despite being
formally non-renormalizable.
  A check of a twisted version of AdS/CFT is performed relating this
5-dimensional non-commutative gauge theory to the theory on N M5 branes,
wrapping an $A_{k-1}$ singularity and placed in an $\Omega$-background. The
operators on the M5 branes, in the $\Omega$-background, are described by a
certain chiral algebra which in the large N limit becomes a $W_{k+\infty}$
algebra. This chiral algebra is recovered from the 5-dimensional gauge theory.
  This argument also provides a holographic explanation of the result of
Maulik-Okounkov and Schiffmann-Vasserot that the $W_{k+\infty}$ algebra acts on
the equivariant cohomology of the moduli of instantons on an $A_{k-1}$
singularity.


title:
On uniform boundedness of dyadic averaging operators in spaces of
  Hardy-Sobolev type

abstract:
  We give an alternative proof of recent results by the authors on uniform
boundedness of dyadic averaging operators in (quasi-)Banach spaces of
Hardy-Sobolev and Triebel-Lizorkin type. This result served as the main tool to
establish Schauder basis properties of suitable enumerations of the univariate
Haar system in the mentioned spaces. The rather elementary proof here is based
on characterizations of the respective spaces in terms of orthogonal compactly
supported Daubechies wavelets.


title: Optical signatures of nonlocal plasmons in graphene

abstract:
  We theoretically investigate under which conditions nonlocal plasmon response
in monolayer graphene can be detected. To this purpose, we study optical
scattering off graphene plasmon resonances coupled using a subwavelength
dielectric grating. We compute the graphene conductivity using the Random Phase
Approximation (RPA) obtaining a nonlocal conductivity and we calculate the
optical scattering of the graphene-grating structure. We then compare this with
the scattering amplitudes obtained if graphene is modeled by the local RPA
conductivity commonly used in the literature. We find that the graphene plasmon
wavelength calculated from the local model may deviate up to $20\%$ from the
more accurate nonlocal model in the small-wavelength (large-$q$) regime. We
also find substantial differences in the scattering amplitudes obtained from
the two models. However, these differences in response are pronounced only for
small grating periods and low temperatures compared to the Fermi temperature.


title:
On the formation of shock for quasilinear wave equations by pulse with
  weak intensity

abstract:
  In this paper we continue to study the shock formation for the
$3$-dimensional quasilinear wave equation \begin{align}\label{main eq}
-(1+3G"(0)(\partial_{t}\phi)^{2})\partial^{2}_{t}\phi+\Delta\phi=0,\tag{\textbf{$\star$}}
\end{align} with $G"(0)$ being a non-zero constant. Since \eqref{main eq}
admits global-in-time solution with small initial data, to present shock
formation, we consider a class of large data. Moreover, no symmetric assumption
is imposed on the data. Compared to our previous work [18], here we pose data
on the hypersurface $\{(t,x)|t=-r_{0}\}$ instead of $\{(t,x)|t=-2\}$, with
$r_{0}$ being arbitrarily large. We prove an a priori energy estimate
independent of $r_{0}$. Therefore a complete description of the solution
behavior as $r_{0}\rightarrow\infty$ is obtained. This allows us to relax the
restriction on the profile of initial data which still guarantees shock
formation. Since \eqref{main eq} can be viewed as a model equation for
describing the propagation of electromagnetic waves in nonlinear dielectric,
the result in this paper reveals the possibility to use wave pulse with weak
intensity to form electromagnetic shocks in laboratory. A main new feature in
the proof is that all estimates in the present paper do \emph{not} depend on
the parameter $r_{0}$, which requires different methods to obtain energy
estimates. As a byproduct, we prove the existence of semi-global-in-time
solutions which lead to shock formation by showing that the limits of the
initial energies exist as $r_{0}\rightarrow\infty$. The proof combines the
ideas in [5] where the the formation of shocks for 3-dimensional relativistic
compressible Euler equations with small initial data is established, and the
short pulse method introduced in [6] and generalized in [15], where the
formation of black holes in general relativity is proved.


title:
Analytic 1D Approximation of the Divertor Broadening S in the Divertor
  Region for Conductive Heat Transport

abstract:
  Topic is the divertor broadening $S$, being a result of perpendicular
transport in the scrape-off layer and resulting in a better distribution of the
power load onto the divertor target. Recent studies show a scaling of the
divertor broadening with an inverse power law to the target temperature $T_t$,
promising its reduction to be a way of distributing the power entering the
divertor volume onto a large surface area.
  It is shown that for pure conductive transport in the divertor region the
suggested inverse power law scaling to $T_t$ is only valid for high target
electron temperatures. For decreasing target temperatures ($T_t < 20\,$eV) the
increase of $S$ stagnates and the conductive model results in a finite value of
$S$ even for zero target temperature. It is concluded that the target
temperature is no valid parameter for a power law scaling, as it is not
representative for the entire divertor volume. This is shown in simulations
solving the 2D heat diffusion equation, which is used as reference for an
analytic 1D model describing the divertor broadening along a field line solely
by the ratio of the perpendicular to the parallel diffusivity.
  By assuming the temperature dependence of these two quantities an integral
form of $S$ is derived, relying only on the temperature distribution along the
separatrix between X-point and target. Integration along the separatrix results
in an approximation for $S$, being in agreement with the 2D simulations. This
model is also applicable to scenarios including heat losses, e.g. due to
radiation.
  Convective transport can not be neglected for high recycling conditions,
hence the derived expression for $S$ is not expected to hold. However, based on
the non-vanishing parallel transport, respective the finite parallel transport
time, the divertor broadening is expected to reach a finite value.


title: Signs of self-dual depth-zero supercuspidal representations

abstract:
  Let $G$ be a quasi-split tamely ramified connected reductive group defined
over a $p$-adic field $F$. We show that if $-1$ is in the $F$-points of the
absolute Weyl group of $G$, then self-dual supercuspidal representations of
$G(F)$ exist. Now assume further that $G$ is unramified and that the center of
$G$ is connected. Let $\pi$ be a generic self-dual depth-zero regular
supercuspidal representation of $G(F)$. We show that the Frobenius-Schur
indicator of $\pi$ is given by the sign by which a certain distinguished
element of the center of $G(F)$ of order two acts on $\pi$.


title: Surface waves on arbitrary vertically-sheared currents

abstract:
  We study dispersion properties of linear surface gravity waves propagating in
an arbitrary direction atop a current profile of depth-varying magnitude using
a piecewise linear approximation, and develop a robust numerical framework for
practical calculation. The method has been much used in the past for the case
of waves propagating along the same axis as the background current, and we
herein extend and apply it to problems with an arbitrary angle between the wave
propagation and current directions. Being valid for all wavelengths without
loss of accuracy, the scheme is particularly well suited to solve problems
involving a broad range of wave vectors, such as ship waves and Cauchy-Poisson
initial value problems for example. We examine the group and phase velocities
over different wavelength regimes and current profiles, highlighting
characteristics due to the depth-variable vorticity. We show an example
application to ship waves on an arbitrary current profile, and demonstrate
qualitative differences in the wake patterns between concave down and concave
up profiles when compared to a constant shear profile with equal depth-averaged
vorticity. We also discuss the nature of additional solutions to the dispersion
relation when using the piecewise-linear model. These are vorticity waves,
drifting vortical structures which are artifacts of the piecewise model. They
are absent for a smooth profile and are spurious in the present context.


title:
Topographical study of TiO2 nanostructure surface for photocatalytic
  hydrogen production

abstract:
  In the present work we investigate the photocatalytic hydrogen production
(water splitting) activity of different Pt loaded TiO2 nanotube layers.
Therefore, we fabricate free standing membranes and fix them in four different
configurations: top up (with initiation layer grass or without) and bottom up
(bottom closed or open), then decorate the tubes with various amounts of Pt and
measure the open-circuit photocatalytic H2 production rate. We find a strong
influence of the configuration with the open top morphology showing the highest
photocatalytic hydrogen production efficiency, these nanotubes yield 3.5 times
more H2 than the least efficient structure (bottom closed). The work therefore
provides valuable guidelines for optimizing TiO2 nanotube layers for
photocatalytic applications.


title:
Metastable Memristive Lines for Signal Transmission and Information
  Processing Applications

abstract:
  Traditional studies of memristive devices have mainly focused on their
applications in non-volatile information storage and information processing.
Here, we demonstrate that the third fundamental component of information
technologies { the transfer of information { can also be employed with
memristive devices. For this purpose, we introduce a metastable memristive
circuit. Combining metastable memristive circuits into a line, one obtains an
architecture capable of transferring a signal edge from one space location to
another. We emphasize that the suggested transmission lines employ only
resistive components. Moreover, their networks (for example, Y-connected lines)
have an information processing capability.


title:
Aminated TiO2 nanotube as a Photoelectrochemical Water Splitting
  photoanode

abstract:
  The present work reports on the enhancement of TiO2 nanotubes
photoelectrochemical water splitting rate by decorating the nanostructure with
an amine layer in a hydrothermal process using diethylenetriamine (DETA). The
aminate coated TiO2 tubes show a stable improvement of the photoresponse in
both UV and visible light spectrum and under hydrothermal conditions, 4-fold
increase of the photoelectrochemical water splitting rate is observed. From
intensity modulated photocurrent spectroscopy (IMPS) measurements significantly
faster electron transport times are observed indicating a surface passivating
effect of the N-decoration.


title:
An Information Theoretic Feature Selection Framework for Big Data under
  Apache Spark

abstract:
  With the advent of extremely high dimensional datasets, dimensionality
reduction techniques are becoming mandatory. Among many techniques, feature
selection has been growing in interest as an important tool to identify
relevant features on huge datasets --both in number of instances and
features--. The purpose of this work is to demonstrate that standard feature
selection methods can be parallelized in Big Data platforms like Apache Spark,
boosting both performance and accuracy. We thus propose a distributed
implementation of a generic feature selection framework which includes a wide
group of well-known Information Theoretic methods. Experimental results on a
wide set of real-world datasets show that our distributed framework is capable
of dealing with ultra-high dimensional datasets as well as those with a huge
number of samples in a short period of time, outperforming the sequential
version in all the cases studied.


title:
The generating function of bivariate Chebyshev polynomials associated
  with the Lie algebra $G_2$

abstract:
  The generating function of the second kind bivariate Chebyshev polynomials
associated with the simple Lie algebra $G_2$ is constructed by the method
proposed in \cite{DKS} and \cite{DKS1}.


title:
Theory and computer simulation of the moir\'e patterns in single-layer
  cylindrical particles

abstract:
  Basing on the theory for arbitrary oriented surfaces, we developed the theory
of the moir\'e effect for cylindrical single-layer objects in the paraxial
approximation. With using the dual grids, the moir\'e effect in the plane
gratings is simulated, as well as the near-axis moir\'e effect in cylinders
including the chiral layouts. The results can be applied to the graphene
layers, to single-walled nanotubes, and to cylinders in general.


title:
Multiband one-dimensional electronic structure and spectroscopic
  signature of Tomonoga-Luttinger liquid behavior in K$_2$Cr$_3$As$_3$

abstract:
  We present Angle-Resolved Photoemission Spectroscopy measurements of the
quasi-one dimensional superconductor K$_2$Cr$_3$As$_3$. We find that the Fermi
surface contains two Fermi surface sheets, with linearly dispersing bands not
displaying any significant band renormalizations. The one-dimensional band
dispersions display a suppression of spectral intensity approaching the Fermi
level according to a linear power law, over an energy range of ~200 meV. This
is interpreted as a signature of Tomonoga-Luttinger liquid physics, which
provides a new perspective on the possibly unconventional superconductivity in
this family of compounds.


title:
Asymptotic analysis of a ferromagnetic lattice spin system with diffuse
  interfacial energy

abstract:
  We give an example of a one-dimensional scalar spin energy with long-range
interactions not satisfying standard decay conditions and which admits a
continuum approximation defined for functions u in BV((0,L),[-1,1]) taking into
account the total variation of u. Related minimum problems show boundary and
size effects in dependence of L.


title: Controlled spacing of self-organized anodic TiO2 nanotubes

abstract:
  We report on how to grow and control self-organized TiO2 nanotube arrays that
show defined and regular gaps between individual nanotubes. For this we use
electrochemical anodization of titanium in fluoride containing di-ethylene
glycol (DEG) electrolytes, with variations in voltage and water content in the
electrolyte. In these specific electrolytes, such nanotubes show a true
spacing, i.e. nanotubes are spaced both at top and at bottom in regular
intervals, this in contrast to classic nanotubes obtained in other organic
electrolytes showing a close-packed organization. We identify critical
parameters, that define the region of existence i.e. under which condition tube
spacing occurs as well as the intertube distance, to be the voltage and the
water content. Using these findings allows to grow tubes where diameter and
spacing can even be independently controlled.


title: Pan-genome Analysis of the Genus Serratia

abstract:
  Pan-genome analysis is a standard procedure to decipher genome heterogeneity
and diversification of bacterial species. Specie evolution is traced by
defining and comparing the core (conserved), accessory (dispensable) and unique
(strain-specific) gene pool with other strains of interest. Here, we present
pan-genome analysis of the genus Serratia, comprising of a dataset of 100
genomes. The isolates have clinical to environmental origin and consist of ten
different species from the genus, along with two subspecies of the
representative strain Serratia marcescens. Out of 19430 non-redundant coding
DNA sequences (CDS) from the dataset, 972 (5%) belonged to the core genome.
Majority of these genes were linked to metabolic function, followed by cellular
processes/signalling, information storage/processing while rest of them were
poorly characterized. 10,135 CDSs (52.16%) were associated with dispensible
genome while 8,321 CDSs (42.82%) were singletons or strain specific. The
Pan-genome orthologs indicated a positive correlation to the number of genomes
whereas negative correlation was obtained for core genome. Genomes were aligned
to obtain information about synteny, insertion/inversion, deletion and
duplications. This study provides insights into variation of Serratia species
and paves way for pan-genome analysis of other bacterial species at genus
level.


title: Why Deep Neural Networks for Function Approximation?

abstract:
  Recently there has been much interest in understanding why deep neural
networks are preferred to shallow networks. We show that, for a large class of
piecewise smooth functions, the number of neurons needed by a shallow network
to approximate a function is exponentially larger than the corresponding number
of neurons needed by a deep network for a given degree of function
approximation. First, we consider univariate functions on a bounded interval
and require a neural network to achieve an approximation error of $\varepsilon$
uniformly over the interval. We show that shallow networks (i.e., networks
whose depth does not depend on $\varepsilon$) require
$\Omega(\text{poly}(1/\varepsilon))$ neurons while deep networks (i.e.,
networks whose depth grows with $1/\varepsilon$) require
$\mathcal{O}(\text{polylog}(1/\varepsilon))$ neurons. We then extend these
results to certain classes of important multivariate functions. Our results are
derived for neural networks which use a combination of rectifier linear units
(ReLUs) and binary step units, two of the most popular type of activation
functions. Our analysis builds on a simple observation: the multiplication of
two bits can be represented by a ReLU.


title: An extension of the P\'olya--Szeg\"o operator inequality

abstract:
  We extend an operator P\'{o}lya--Szeg\"{o} type inequality involving the
operator geometric mean to any arbitrary operator mean under some mild
conditions. Utilizing the Mond--Pe\v{c}ari\'c method, we present some other
related operator inequalities as well.


title: Seven-Disk Manifold, alpha-attractors and B-modes

abstract:
  Cosmological alpha-attractor models in \cN=1 supergravity are based on
hyperbolic geometry of a Poincar\'e disk with the radius square {\cal
R}^2=3\alpha. The predictions for the B-modes, r\approx 3\alpha {4\over N^2},
depend on moduli space geometry and are robust for a rather general class of
potentials. Here we notice that starting with M-theory compactified on a
7-manifold with G_2 holonomy, with a special choice of Betti numbers, one can
obtain d=4 \cN=1 supergravity with rank 7 scalar coset \Big[{SL(2)\over
SO(2)}\Big]^7. In a model where these 7 unit size Poincar\'e disks have
identified moduli one finds that 3 alpha =7. Assuming that the moduli space
geometry of the phenomenological models is inherited from this version of
M-theory, one would predict r \approx 10^{-2} for 53 e-foldings. We also
describe the related maximal supergravity and M/string theory models leading to
preferred values 3 alpha =1,2,3,4,5,6,7.


title:
Analytical theory and possible detection of the $ac$ quantum spin Hall
  effect

abstract:
  We develop an analytical theory of the low-frequency $ac$ quantum spin Hall
(QSH) effect based upon the scattering matrix formalism. It is shown that the
$ac$ QSH effect can be interpreted as a bulk quantum pumping effect. When the
electron spin is conserved, the integer-quantized $ac$ spin Hall conductivity
can be linked to the winding numbers of the reflection matrices in the
electrodes, which also equal to the bulk spin Chern numbers of the QSH
material. Furthermore, a possible experimental scheme by using ferromagnetic
metals as electrodes is proposed to detect the topological $ac$ spin current by
electrical means.


title:
Estimates of operator convex and operator monotone functions on bounded
  intervals

abstract:
  Recently the behavior of operator monotone functions on unbounded intervals
with respect to the relation of strictly positivity has been investigated. In
this paper we deeply study such behavior not only for operator monotone
functions but also for operator convex functions on bounded intervals. More
precisely, we prove that if $f$ is a nonlinear operator convex function on a
bounded interval $(a,b)$ and $A, B$ are bounded linear operators acting on a
Hilbert space with spectra in $(a,b)$ and $A-B$ is invertible, then
$sf(A)+(1-s)f(B)>f(sA+(1-s)B)$. A short proof for a similar known result
concerning a nonconstant operator monotone function on $[0,\infty)$ is
presented. Another purpose is to find a lower bound for $f(A)-f(B)$, where $f$
is a nonconstant operator monotone function, by using a key lemma. We also give
an estimation of the Furuta inequality, which is an excellent extension of the
L\"owner--Heinz inequality.


title: Unusual boundary effect on coherency of two-band superconductivity

abstract:
  We demonstrate that the healing of two-band superconductivity near the
surface of the system is governed by length scales which are drastically
different from correlation lengths. Similar to the one-band case, one of the
characteristic lengths diverges at critical temperature $T_c$, while another
one shows unusual behaviour having singularity at $T_{c+}<T_c$. By moving away
from the boundary, these scales approach coherence lengths in the bulk state,
where the divergence at $T_{c+}$ is removed by arbitrary weak interband
coupling. Such a boundary-driven modification in coherency affects proximity
phenomenon. We show that critical temperature of binary NS system can exhibit
an inflection near $T_{c+}$ as two-band superconducting layer becomes thinner.


title: Tensorial Mixture Models

abstract:
  Casting neural networks in generative frameworks is a highly sought-after
endeavor these days. Contemporary methods, such as Generative Adversarial
Networks, capture some of the generative capabilities, but not all. In
particular, they lack the ability of tractable marginalization, and thus are
not suitable for many tasks. Other methods, based on arithmetic circuits and
sum-product networks, do allow tractable marginalization, but their performance
is challenged by the need to learn the structure of a circuit. Building on the
tractability of arithmetic circuits, we leverage concepts from tensor analysis,
and derive a family of generative models we call Tensorial Mixture Models
(TMMs). TMMs assume a simple convolutional network structure, and in addition,
lend themselves to theoretical analyses that allow comprehensive understanding
of the relation between their structure and their expressive properties. We
thus obtain a generative model that is tractable on one hand, and on the other
hand, allows effective representation of rich distributions in an easily
controlled manner. These two capabilities are brought together in the task of
classification under missing data, where TMMs deliver state of the art
accuracies with seamless implementation and design.


title:
Competing role of interactions in synchronization of exciton-polariton
  condensates

abstract:
  We present a theoretical study of synchronization dynamics in incoherently
pumped exciton-polariton condensates in coupled polariton traps. Our analysis
is based on a coupled-mode theory for the generalized Gross-Pitaevskii
equation, which employs an expansion in non-Hermitian, pump-dependent modes
appropriate for the pumped geometry. We find that polariton-polariton and
reservoir-polariton interactions play competing roles and lead to qualitatively
different synchronized phases of the coupled polariton modes as pumping power
is increased. Crucially, these interactions can also act against each other to
hinder synchronization. We map out a phase diagram and discuss the general
characteristics of these phases using a generalized Adler equation.


title:
Tantalum nitride nanotube photoanodes: establishing a beneficial
  back-contact by lift-off and transfer to titanium nitride layer

abstract:
  In this work we introduce the use of TiN/Ti2 N layers as a back contact for
lifted-off membranes of anodic Ta3N5 nanotube layers. In photoelectrochemical
H2 generation experiments under simulated AM 1.5G light, shift of the onset
potential for anodic photocurrents to lower potentials is observed, as well as
a higher magnitude of the photocurrents compared to conventional Ta3N5
nanotubes (~ 0.5 V RHE ). We ascribe this beneficial effect to the improved
conductive properties of the TiNx -based back contact layer that enables a
facilitated electron-transport for tantalum-nitride based materials to the
conductive substrate.


title: Network segregation in a model of misinformation and fact checking

abstract:
  Misinformation under the form of rumor, hoaxes, and conspiracy theories
spreads on social media at alarming rates. One hypothesis is that, since social
media are shaped by homophily, belief in misinformation may be more likely to
thrive on those social circles that are segregated from the rest of the
network. One possible antidote is fact checking which, in some cases, is known
to stop rumors from spreading further. However, fact checking may also backfire
and reinforce the belief in a hoax. Here we take into account the combination
of network segregation, finite memory and attention, and fact-checking efforts.
We consider a compartmental model of two interacting epidemic processes over a
network that is segregated between gullible and skeptic users. Extensive
simulation and mean-field analysis show that a more segregated network
facilitates the spread of a hoax only at low forgetting rates, but has no
effect when agents forget at faster rates. This finding may inform the
development of mitigation techniques and overall inform on the risks of
uncontrolled misinformation online.


title: Cuddling Ellipsoids: Densest local structures of uniaxial ellipsoids

abstract:
  Connecting the collective behavior of disordered systems with local structure
on the particle scale is an important challenge, for example in granular and
glassy systems. Compounding complexity, in many scientific and industrial
applications, particles are polydisperse, aspherical or even of varying shape.
Here, we investigate a generalization of the classical kissing problem in order
to understand the local building blocks of packings of aspherical grains. We
numerically determine the densest local structures of uniaxial ellipsoids by
minimizing the Set Voronoi cell volume around a given particle. Depending on
the particle aspect ratio, different local structures are observed and
classified by symmetry and Voronoi coordination number. In extended disordered
packings of frictionless particles, knowledge of the densest structures allows
to rescale the Voronoi volume distributions onto the single-parameter family of
$k$-Gamma distributions. Moreover, we find that approximate icosahedral
clusters are found in random packings, while the optimal local structures for
more aspherical particles are not formed.


title: Decay of the Weyl curvature in expanding black hole cosmologies

abstract:
  This paper is motivated by the non-linear stability problem for the expanding
region of Kerr de Sitter cosmologies in the context of Einstein's equations
with positive cosmological constant. We show that under dynamically realistic
assumptions the conformal Weyl curvature of the spacetime decays towards future
null infinity. More precisely we establish decay estimates for Weyl fields
which are (i) uniform (with respect to a global time function) (ii) optimal
(with respect to the rate) and (iii) consistent with a global existence proof
(in terms of regularity). The proof relies on a geometric positivity property
of compatible currents which is a manifestation of the global redshift effect
capturing the expansion of the spacetime.


title:
NectarCAM, a camera for the medium sized telescopes of the Cherenkov
  Telescope Array

abstract:
  NectarCAM is a camera proposed for the medium-sized telescopes of the
Cherenkov Telescope Array (CTA) which covers the core energy range of ~100 GeV
to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the
heart of which is a GHz sampling Switched Capacitor Array and 12-bit Analog to
Digital converter. The camera will be equipped with 265 7-photomultiplier
modules, covering a field of view of 8 degrees. Each module includes
photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and
Ethernet transceiver. The recorded events last between a few nanoseconds and
tens of nanoseconds. The expected performance of the camera are discussed.
Prototypes of NectarCAM components have been built to validate the design.
Preliminary results of a 19-module mini-camera are presented, as well as future
plans for building and testing a full size camera.


title:
Monotonicity of Entropy and Fisher Information: A Quick Proof via
  Maximal Correlation

abstract:
  A simple proof is given for the monotonicity of entropy and Fisher
information associated to sums of i.i.d. random variables. The proof relies on
a characterization of maximal correlation for partial sums due to Dembo, Kagan
and Shepp.


title: Strategic allocation of flight plans: an evolutionary point of view

abstract:
  We consider the simplified model of strategic allocation of trajectories in
the airspace presented in a previous publication. Two types of companies,
characterized by different cost functions, compete for allocation of
trajectories in the airspace. We study how the equilibrium state of the model
depends on the traffic demand and number of airports. We show that in a mixed
population environment the equilibrium solution is not the optimal at the
global level, but rather than it tends to have a larger fraction of companies
who prefer to delay the departure time rather taking a longer routes. Finally
we study the evolutionary dynamics investigating the fluctuations of airline
types around the equilibrium and the speed of convergence toward it in finite
populations. We find that the equilibrium point is shifted by the presence of
noise and is reached more slowly.


title:
Spin-wave spectra in periodically surface-modulated ferromagnetic thin
  films

abstract:
  This article presents theoretical results for the dynamic response of
periodically surface-modulated ferromagnetic thin films. For such system, the
role of the periodic dipolar field induced by the modulation is addressed by
using the plane-wave method. By controlling the geometry of the modulated
volumes within the film, the frequency modes and spatial profiles of spin waves
can be manipulated. The angular dependence of the frequency band-gaps unveils
the influence of both dynamic and static magnetic charges, which reside in the
edges of the etching periodic zones, and it is stablished that band-gap widths
created by static magnetic charges are broader than the one created by dynamic
magnetic charges. To corroborate the validity of the model, the theoretical
results are compared with ferromagnetic resonance simulations, where a very
good agreement is achieved between both methods. The theoretical model allows
for a detailed understanding of the physics underlying these kind of systems,
thereby providing an outlook to potential applications associated with magnonic
crystals-based devices.


title: Low-energy electronic recoil in xenon detectors by solar neutrinos

abstract:
  Low-energy electronic recoil caused by solar neutrinos in multi-ton xenon
detectors is an important subject not only because it is a source of the
irreducible background for direct searches of weakly-interacting massive
particles (WIMPs), but also because it provides a viable way to measure the
solar $pp$ and $^{7}\textrm{Be}$ neutrinos at the precision level of current
standard solar model predictions. In this work we perform $\textit{ab initio}$
many-body calculations for the structure, photoionization, and
neutrino-ionization of xenon. It is found that the atomic binding effect yields
a sizable suppression to the neutrino-electron scattering cross section at low
recoil energies. Compared with the previous calculation based on the free
electron picture, our calculated event rate of electronic recoil in the same
detector configuration is reduced by about $25\%$. We present in this paper the
electronic recoil rate spectrum in the energy window of 100 eV - 30 keV with
the standard per ton per year normalization for xenon detectors, and discuss
its implication for low energy solar neutrino detection (as the signal) and
WIMP search (as a source of background).

categories: hep-ex hep-ph nucl-ex nucl-th physics.ins-det


title:
Probabilistic record linkage in astronomy: Directional
  cross-identification and beyond

abstract:
  Modern astronomy increasingly relies upon systematic surveys, whose dedicated
telescopes continuously observe the sky across varied wavelength ranges of the
electromagnetic spectrum; some surveys also observe non-electromagnetic
"messengers," such as high-energy particles or gravitational waves. Stars and
galaxies look different through the eyes of different instruments, and their
independent measurements have to be carefully combined to provide a complete,
sound picture of the multicolor and eventful universe. The association of an
object's independent detections is, however, a difficult problem
scientifically, computationally, and statistically, raising varied challenges
across diverse astronomical applications. The fundamental problem is finding
records in survey databases with directions that match to within the direction
uncertainties. Such astronomical versions of the record linkage problem are
known by various terms in astronomy: cross-matching, cross-identification, and
directional, positional, or spatio-temporal coincidence assessment. Astronomers
have developed several statistical approaches for such problems, largely
independently of related developments in other disciplines. Here we review
emerging approaches that compute (Bayesian) probabilities for the hypotheses of
interest: possible associations, or demographic properties of a cosmic
population that depend on identifying associations. Many cross-identification
tasks can be formulated within a hierarchical Bayesian partition model
framework, with components that explicitly account for astrophysical effects
(e.g., source brightness vs. wavelength, source motion, or source extent),
selection effects, and measurement error. We survey recent developments, and
highlight important open areas for future research.


title: Time-Resolved Cavity Nano-Optomechanics in the 20-100 GHz range

abstract:
  Applications of cavity optomechanics span from gravitational wave detection
to the study of quantum motion states in mesoscopic mechanical systems. The
engineering of resonators supporting strongly interacting mechanical and
optical modes is central to these developments. However, current technological
and experimental approaches limit the accessible mechanical frequencies to a
few GHz, imposing hard constraints on quantum mechanical studies. Here we
demonstrate the optical control of 20-100~GHz mechanical modes confined in the
three dimensions within semiconductor nano-optomechanical pillar cavities. We
use a time-resolved transient optical reflectivity technique and access both
the energy spectrum and dynamics of the mechanical modes at the picosecond
timescale. A strong increase of the optomechanical coupling upon reducing the
pillar size is observed together with unprecedent room temperature Q-frequency
products above $10^{14}$. The measurements also reveal sideband generation in
the optomechanical response. Such resonators can naturally integrate quantum
wells and quantum dots, enabling novel applications in cavity quantum
electrodynamics and high frequency nanomechanics.


title: Noisy quantum walks of two indistinguishable interacting particles

abstract:
  We investigate the dynamics of continuous-time two-particle quantum walks on
a one-dimensional noisy lattice. Depending on the initial condition, we show
how the interplay between particle indistinguishability and interaction
determines distinct propagation regimes. A realistic model for the environment
is considered by introducing non-Gaussian noise as time-dependent fluctuations
of the tunneling amplitudes between adjacent sites. We observe that the
combined effect of particle interaction and fast noise (weak coupling with the
environment) provides a faster propagation compared to the noiseless case. This
effect can be understood in terms of the band structure of the Hubbard model,
and a detailed analysis as a function of both noise and system parameters is
presented.


title: Removal of Batch Effects using Distribution-Matching Residual Networks

abstract:
  Sources of variability in experimentally derived data include measurement
error in addition to the physical phenomena of interest. This measurement error
is a combination of systematic components, originating from the measuring
instrument, and random measurement errors. Several novel biological
technologies, such as mass cytometry and single-cell RNA-seq, are plagued with
systematic errors that may severely affect statistical analysis if the data is
not properly calibrated. We propose a novel deep learning approach for removing
systematic batch effects. Our method is based on a residual network, trained to
minimize the Maximum Mean Discrepancy (MMD) between the multivariate
distributions of two replicates, measured in different batches. We apply our
method to mass cytometry and single-cell RNA-seq datasets, and demonstrate that
it effectively attenuates batch effects.


title:
Periodic solutions of N-vortex type Hamiltonian systems near the domain
  boundary

abstract:
  The paper deals with the existence of nonstationary collision-free periodic
solutions of singular first order Hamiltonian systems of $N$-vortex type in a
domain $\Omega\subset\mathbb{C}$. These are solutions
$z(t)=(z_1(t),\dots,z_N(t))$ of \[ \dot{z}_j(t)=-i\nabla_{z_j}
H_\Omega\big(z(t)\big),\quad j=1,\dots,N, \tag{HS} \] where the Hamiltonian
$H_\Omega$ has the form \[ H_\Omega(z_1,\dots,z_N)
  = -\sum_{{j,k=1}\over{j\ne k}}^N \frac{1}{2\pi}\log|z_j-z_k| -\sum_{j,k=1}^N
g(z_j,z_k). \] The function $g:\Omega\times\Omega\to\mathbb{R}$ is required to
be of class $C^3$ and symmetric, the regular part of a hydrodynamic Green
function being our model. The Hamiltonian is unbounded from above and below,
and the associated action integral is not defined on an open subset of the
space of periodic $H^{1/2}$ functions.
  Given a closed connected component $\Gamma\subset\partial\Omega$ of class
$C^3$ we are interested in periodic solutions of (HS) near $\Gamma$. We present
quite general conditions on the behavior of $g$ near $\Gamma$ which imply that
there exists a family of periodic solutions $z^{(r)}(t)$, $0<r<\overline{r}$,
with arbitrarily small minimal period $T_r\to0$ as $r\to0$, and such that the
"point vortices" $z_j^{(r)}(t)$ approach $\Gamma$ as $r\to0$. The solutions are
choreographies, i.e.\ $z_j^{(r)}(t)$ moves on the same trajectory as
$z_1^{(r)}(t)$ with a phase shift. We can also relate the speed of each vortex
with the curvature of $\Gamma$.


title: Layer Formation in Sedimentary Fingering Convection

abstract:
  When particles settle through a stable temperature or salinity gradient they
can drive an instability known as sedimentary fingering convection. This
phenomenon is thought to occur beneath sediment-rich river plumes in lakes and
oceans, in the context of marine snow where decaying organic materials serve as
the suspended particles, or in the atmosphere in the presence of aerosols or
volcanic ash. Laboratory experiments of Houk and Green (1973) and Green (1987)
have shown sedimentary fingering convection to be similar to the more commonly
known thermohaline fingering convection in many ways. Here, we study the
phenomenon using 3D direct numerical simulations. We find evidence for layer
formation in sedimentary fingering convection in regions of parameter space
where it does not occur for non-sedimentary systems. This is due to two
complementary effects. Sedimentation affects the turbulent fluxes and broadens
the region of parameter space unstable to the $\gamma$-instability (Radko 2003)
to include systems at larger density ratios. It also gives rise to a new
layering instability that exists in $\gamma-$stable regimes. The former is
likely quite ubiquitous in geophysical systems for sufficiently large settling
velocities, while the latter probably grows too slowly to be relevant, at least
in the context of sediments in water.


title: Highly controlled coating of a biomimetic polymer in TiO2 nanotubes

abstract:
  Highly controlled coating of biomimetic polydopamine (PDA) was achieved on
titanium dioxide nanotubes (TiO2 NTs) by exposing TiO2 NT arrays to a slightly
alkaline dopamine solution. The thin films act as photonic sensitizers
(enhancing photocurrents and photodegradation) in the visible light range. The
PDA coatings can furthermore be used as a platform for decorating the TiO2 NTs
with different co-catalysts and metal nanoparticles (NPs).


title:
Le Potier's strange duality, quot schemes, and multiple point formulas
  for del Pezzo surfaces

abstract:
  We study Le Potier's strange duality on del Pezzo surfaces using quot schemes
to construct independent sections of theta line bundles on moduli spaces of
sheaves, one of which is the Hilbert scheme of n points. For n at most 7, we
use multiple point formulas to count the length of the quot scheme, which
agrees with the dimension of the space of sections on the Hilbert scheme. When
the surface is the projective plane and n is arbitrary, we use nice resolutions
of general stable sheaves to show that the quot schemes that arise are finite
and reduced. Combining our results, we obtain a lower bound on the rank of the
strange duality map, as well as evidence that the map is injective when n is at
most 7.


title:
Nanohelices as superlattices: Bloch oscillations and electric dipole
  transitions

abstract:
  Subjecting a nanohelix to a transverse electric field gives rise to
superlattice behavior with tunable electronic properties. We theoretically
investigate such a system and find Bloch oscillations and negative differential
conductance when a longitudinal electric field (along the nanohelix axis) is
also applied. Furthermore, we study dipole transitions across the
transverse-electric-field-induced energy gap, which can be tuned to the
eulogized terahertz frequency range by experimentally attainable external
fields. We also reveal a photogalvanic effect by shining circularly polarized
light onto our helical quantum wire.


title: Baxter posets

abstract:
  We define a family of combinatorial objects, which we call Baxter posets. We
prove that Baxter posets are counted by the Baxter numbers by showing that they
are the adjacency posets of diagonal rectangulations. Given a diagonal
rectangulation, we describe the cover relations in the associated Baxter poset.
Given a Baxter poset, we describe a method for obtaining the associated Baxter
permutation and the associated twisted Baxter permutation.


title: Testing gauge-invariant perturbation theory

abstract:
  Gauge-invariant perturbation theory for theories with a Brout-Englert-Higgs
effect, as developed by Fr\"ohlich, Morchio and Strocchi, starts out from
physical, exactly gauge-invariant quantities as initial and final states. These
are composite operators, and can thus be considered as bound states. In case of
the standard model, this reduces almost entirely to conventional perturbation
theory. This explains the success of conventional perturbation theory for the
standard model. However, this is due to the special structure of the standard
model, and it is not guaranteed to be the case for other theories. Here, we
review gauge-invariant perturbation theory. Especially, we show how it can be
applied and that it is little more complicated than conventional perturbation
theory, and that it is often possible to utilize existing results of
conventional perturbation theory. Finally, we present tests of the predictions
of gauge-invariant perturbation theory, using lattice gauge theory, in three
different settings. In one case, the results coincide with conventional
perturbation theory and with the lattice results. In a second case, it appears
that the results of gauge-invariant perturbation theory agree with the lattice,
but differ from conventional perturbation theory. In the third case both
approaches fail due to quantum fluctuations.


title:
HI and cosmological constraints from intensity mapping, optical, and CMB
  surveys

abstract:
  We forecast constraints on neutral hydrogen (HI) and cosmological parameters
using near-term intensity mapping surveys with instruments such as BINGO,
MeerKAT, and the SKA, and Stage III and IV optical galaxy surveys. If
foregrounds and systematic effects can be controlled - a problem which becomes
much easier in cross-correlation - these surveys will provide exquisite
measurements of the HI density and bias, as well as measurements of the growth
of structure, the angular diameter distance, and the Hubble rate, over a wide
range of redshift. We also investigate the possibility of detecting the late
time ISW effect using the Planck satellite and forthcoming intensity mapping
surveys, finding that a large sky survey with Phase 1 of the SKA can achieve a
near optimal detection.


title: Remarks on the Standard Model predictions for $R(D)$ and $R(D^*)$

abstract:
  Semileptonic $b \to c$ transitions, and in particular the ratios $R(D^{(*)})
= \frac{\Gamma(B \rightarrow D^{(*)} \tau \nu )}{\Gamma(B \rightarrow D^{(*)}
\ell \nu )}$, can be used to test the universality of the weak interactions. In
light of the recent discrepancies between the experimental measurements of
these observables by BaBar, Belle and LHCb and the Standard Model predicted
values, we study the robustness of the latter. Our analysis reveals that $R(D)$
might be enhanced by lepton mass effects associated to the mostly unknown
scalar form factor. In constrast, the Standard Model prediction for $R(D^*)$ is
found to be more robust, since possible pollutions from $B^*$ contributions
turn out to be negligibly small, which indicates that $R(D^*)$ is a promising
observable for searches of new physics.


title:
Measurement of differential cross sections for top quark pair production
  using the lepton+jets final state in proton-proton collisions at 13 TeV

abstract:
  Differential and double-differential cross sections for the production of top
quark pairs in proton-proton collisions at 13 TeV are measured as a function of
jet multiplicity and of kinematic variables of the top quarks and the top
quark-antiquark system. This analysis is based on data collected by the CMS
experiment at the LHC corresponding to an integrated luminosity of 2.3 inverse
femtobarns. The measurements are performed in the lepton+jets decay channels
with a single muon or electron in the final state. The differential cross
sections are presented at particle level, within a phase space close to the
experimental acceptance, and at parton level in the full phase space. The
results are compared to several standard model predictions.


title:
Multi-Layer Precoding: A Potential Solution for Full-Dimensional Massive
  MIMO Systems

abstract:
  Massive multiple-input multiple-output (MIMO) systems achieve high sum
spectral efficiency by offering an order of magnitude increase in multiplexing
gains. In time division duplexing systems, however, the reuse of uplink
training pilots among cells results in additional channel estimation error,
which causes downlink inter-cell interference, even when large numbers of
antennas are employed. Handling this interference with conventional network
MIMO techniques is challenging due to the large channel dimensionality.
Further, the implementation of large antenna precoding/combining matrices is
associated with high hardware complexity and power consumption. In this paper,
we propose multi-layer precoding to enable efficient and low complexity
operation in full-dimensional massive MIMO, where a large number of antennas is
used in two dimensions. In multi-layer precoding, the precoding matrix of each
base station is written as a product of a number of precoding matrices, each
one called a layer. Multi-layer precoding (i) leverages the directional
characteristics of large-scale MIMO channels to manage inter-cell interference
with low channel knowledge requirements, and (ii) allows for an efficient
implementation using low-complexity hybrid analog/digital architectures. We
present a specific multi-layer precoding design for full-dimensional massive
MIMO systems. The performance of this precoding design is analyzed and the
per-user achievable rate is characterized for general channel models. The
asymptotic optimality of the proposed multi-layer precoding design is then
proved for some special yet important channels. Numerical simulations verify
the analytical results and illustrate the potential gains of multi-layer
precoding compared to traditional pilot-contaminated massive MIMO solutions.


title:
Control of quantum localization and classical diffusion in laser-kicked
  molecular rotors

abstract:
  We experimentally study a system of quantum kicked rotors - an ensemble of
diatomic molecules exposed to a periodic sequence of ultrashort laser pulses.
In the regime, where the underlying classical dynamics is chaotic, we
investigate the quantum phenomenon of dynamical localization by means of
state-resolved coherent Raman spectroscopy. We examine the dependence of the
exponentially localized angular momentum distribution and of the total
rotational energy on the time period between the pulses and their amplitude.
The former parameter is shown to provide control over the localization center,
whereas the latter one controls the localization length. Similar control of the
center and width of a nonlocalized rotational distribution is demonstrated in
the limit of classical diffusion, established by adding noise to the periodic
pulse sequence.


title:
On the price of anarchy in a single server queue with heterogenous
  service valuations induced by travel costs

abstract:
  This work presents a variation of Naor's strategic observable model (1969),
by adding a component of customer heterogeneity induced by the location of
customers in relation to the server. Accordingly, customers incur a travel cost
which depends linearly on the distance of the customer from the server. The
arrival of customers with distances less than x is assumed to be a Poisson
process with rate lambda(x)=int_0^x h(y)dy<\infty, where h(y) is a nonnegative
intensity function of the distance y. In a loss system M/G/1/1 we define the
threshold Nash equilibrium strategy x_e and the optimal social threshold
strategy x^*. We show that if the rate of arriving customers is bounded then
PoA converges to 1 when x_e \to\infty, i.e., in the limit there is no
difference between the social and equilibrium optimal benefits. The rest of the
paper is dedicated for the case in which the rate of arriving customers is
unbounded. We develop an explicit formula to calculate lim_{x_e\to \infty}PoA
when it exists. We present sufficient conditions for the limit to exist and for
the existence of a simple formula for calculating it. We prove that if the
relation between two intensity functions converges to a positive constant, then
the corresponding limits of PoA coincide. If, on the other hand, one intensity
function is larger than the other from some point on, then under certain
conditions the limit of PoA (if exists) will be larger for the larger intensity
function. For all intensity functions h, we prove that if h converges to a
constant then PoA converges to 2, and that if from some point on h decreases
(increases) monotonically then the limit of PoA, if exists, is smaller (larger)
than 2. In a system with a queue we prove that the price of anarchy may be
unbounded already in the simple case of uniform arrival, namely h~c, where c>0.


title: Maximum of the Ginzburg-Landau fields

abstract:
  We study two dimensional massless field in a box with potential $V\left(
\nabla \phi \left( \cdot \right) \right) $ and zero boundary condition, where
$V$ is any symmetric and uniformly convex function. Naddaf-Spencer and Miller
proved the macroscopic averages of this field converge to a continuum Gaussian
free field. In this paper we prove the distribution of local marginal $\phi
\left( x\right) $, for any $x$ in the bulk, has a Gaussian tail. We further
characterize the leading order of the maximum and dimension of high points of
this field, thus generalize the results of Bolthausen-Deuschel-Giacomin and
Daviaud for the discrete Gaussian free field.


title:
Low-Cost Energy Meter Calibration Method for Measurement and
  Verification

abstract:
  Energy meters need to be calibrated for use in Measurement and Verification
(M&V) projects. However, calibration can be prohibitively expensive and affect
project feasibility negatively. This study presents a novel low-cost in-situ
meter data calibration technique using a relatively low accuracy commercial
energy meter as a calibrator. Calibration is achieved by combining two machine
learning tools: the SIMulation EXtrapolation (SIMEX) Measurement Error Model,
and Bayesian regression. The model is trained or calibrated on half-hourly
building energy data for 24 hours. Measurements are then compared to the true
values over the following months to verify the method. Results show that the
hybrid method significantly improves parameter estimates and goodness of fit
when compared to Ordinary Least Squares regression or standard SIMEX. This
study also addresses the effect of mismeasurement in energy monitoring, and
implements a powerful technique for mitigating the bias that arises because of
it. Meters calibrated by the technique presented have satisfactory accuracy for
most M&V applications, at a significantly lower cost.


title:
Second harmonic generation in nano-structured thin-film lithium niobate
  waveguides

abstract:
  Integrated thin-film lithium niobate platform has recently emerged as a
promising candidate for next-generation, high-efficiency wavelength conversion
systems that allow dense packaging and mass-production. Here we demonstrate
efficient, phase-matched second harmonic generation in lithographically-defined
thin-film lithium niobate waveguides with sub-micron dimensions. Both modal
phase matching in fixed-width waveguides and quasi-phase matching in
periodically grooved waveguides are theoretically proposed and experimentally
demonstrated. Our low-loss (~ 3.0 dB/cm) nanowaveguides possess normalized
conversion efficiencies as high as 41% W-1cm-2.


title: Intrinsic Electron Mobility Limits in beta-Ga2O3

abstract:
  By systematically comparing experimental and theoretical transport
properties, we identify the polar optical phonon scattering as the dominant
mechanism limiting electron mobility in beta-Ga2O3 to lower than 200 cm2/Vs at
300 K for donor doping densities lower than 1018 cm-3. In spite of similar
electron effective mass of beta-Ga2O3 to GaN, the electron mobility is 10x
lower because of a massive Frohlich interaction, due to the low phonon energies
stemming from the crystal structure and strong bond ionicity. Based on the
theoretical and experimental analysis, we provide an empirical expression for
electron mobility in beta-Ga2O3 that should help calibrate its potential in
high performance device design and applications.


title: Simultaneous Credible Regions for Multiple Changepoint Locations

abstract:
  Within a Bayesian retrospective framework, we present a way of examining the
distribution of \cps through a novel set estimator. For a given level,
$\alpha$, we aim at smallest sets that cover all \cps with a probability of at
least $1-\alpha$. These so-called smallest simultaneous credible regions,
computed for certain values of $\alpha$, provide parsimonious representations
of the possible \cp locations. In addition, combining them for a range of
different $\alpha$'s enables very informative yet condensed visualisations.
Therewith we allow for the evaluation of model choices and the analysis of \cp
data to an unprecedented degree. This approach exhibits superior sensitivity,
specificity and interpretability in comparison with highest density regions,
marginal inclusion probabilities and confidence intervals inferred by \stepR.
Whilst their direct construction is usually intractable, asymptotically correct
solutions can be derived from posterior samples. This leads to a novel
NP-complete problem. Through reformulations into an Integer Linear Program we
show empirically that a fast greedy heuristic computes virtually exact
solutions.


title: The obstacle problem for the fractional Laplacian with critical drift

abstract:
  We study the obstacle problem for the fractional Laplacian with drift,
$\min\left\{(-\Delta)^s u + b \cdot \nabla u,\,u -\varphi\right\} = 0$ in
$\mathbb{R}^n$, in the critical regime $s = \frac{1}{2}$.
  Our main result establishes the $C^{1,\alpha}$ regularity of the free
boundary around any regular point $x_0$, with an expansion of the form \[
u(x)-\varphi(x) = c_0\big((x-x_0)\cdot e\big)_+^{1+\tilde\gamma(x_0)} +
o\left(|x-x_0|^{1+\tilde\gamma(x_0)+\sigma}\right), \] \[ \tilde{\gamma}(x_0) =
\frac{1}{2}+\frac{1}{\pi} \arctan (b\cdot e), \] where $e \in \mathbb{S}^{n-1}$
is the normal vector to the free boundary, $\sigma >0$, and $c_0> 0$.
  We also establish an analogous result for more general nonlocal operators of
order 1. In this case, the exponent $\tilde\gamma(x_0)$ also depends on the
operator.


title:
Parallel ICA reveals linked patterns of structural damage and fMRI
  language task activation in chronic post-stroke aphasia

abstract:
  Structural and functional MRI studies of patients with post-stroke language
deficits have contributed substantially to our understanding of how
cognitive-behavioral impairments relate to the location of structural damage
and to the activation of surviving brain regions during language processing,
respectively. However, very little is known about how inter-patient variability
in language task activation relates to variability in the structures affected
by stroke. Here, we used parallel independent component analysis (pICA) to
characterize links between patterns of structural damage and patterns of
functional MRI activation during semantic decisions. The pICA analysis revealed
a significant association between a lesion component featuring damage to left
posterior temporo-parietal cortex and the underlying deep white matter and an
fMRI component featuring (1) heightened activation in a primarily right
hemispheric network of frontal, temporal, and parietal regions, and (2) reduced
activation in areas associated with the semantic network activated by healthy
controls. Stronger loading parameters on both the lesion and fMRI activation
components were associated with poorer language test performance. Fiber
tracking suggests that lesions affecting the left posterior temporo-parietal
cortex and deep white matter may lead to the simultaneous disruption of
multiple long-range structural pathways connecting distal language areas.
Damage to the left posterior temporo-parietal cortex and underlying white
matter may (1) impede the language task-driven recruitment of canonical left
hemispheric language and other areas (e.g. the right anterior temporal lobe and
default mode regions) that likely support residual language function after
stroke, and (2) lead to the compensatory recruitment of right hemispheric
fronto-temporo-parietal networks for tasks requiring semantic processing.


title: Gauged spinning models with deformed supersymmetry

abstract:
  New models of the SU(2|1) supersymmetric mechanics based on gauging the
systems with dynamical (1,4,3) and semi-dynamical (4,4,0) supermultiplets are
presented. We propose a new version of SU(2|1) harmonic superspace approach
which makes it possible to construct the Wess-Zumino term for interacting
(4,4,0) multiplets. A new N=4 extension of d=1 Calogero-Moser multiparticle
system is obtained by gauging the U(n) isometry of matrix SU(2|1) harmonic
superfield model.


title: Maximizing Broadcast Throughput Under Ultra-Low-Power Constraints

abstract:
  Wireless object tracking applications are gaining popularity and will soon
utilize emerging ultra-low-power device-to-device communication. However,
severe energy constraints require much more careful accounting of energy usage
than what prior art provides. In particular, the available energy, the
differing power consumption levels for listening, receiving, and transmitting,
as well as the limited control bandwidth must all be considered. Therefore, we
formulate the problem of maximizing the throughput among a set of heterogeneous
broadcasting nodes with differing power consumption levels, each subject to a
strict ultra-low-power budget. We obtain the oracle throughput (i.e., maximum
throughput achieved by an oracle) and use Lagrangian methods to design EconCast
- a simple asynchronous distributed protocol in which nodes transition between
sleep, listen, and transmit states, and dynamically change the transition
rates. EconCast can operate in groupput or anyput modes to respectively
maximize two alternative throughput measures. We show that EconCast approaches
the oracle throughput. The performance is also evaluated numerically and via
extensive simulations and it is shown that EconCast outperforms prior art by 6x
- 17x under realistic assumptions. Moreover, we evaluate EconCast's latency
performance and consider design tradeoffs when operating in groupput and anyput
modes. Finally, we implement EconCast using the TI eZ430-RF2500-SEH energy
harvesting nodes and experimentally show that in realistic environments it
obtains 57% - 77% of the achievable throughput.


title: The particle-hole map: formal derivation and numerical implementation

abstract:
  The particle-hole map (PHM) is a tool to visualize electronic excitations,
based on representations in a canonical orbital transition space. Introduced as
an alternative to the transition density matrix, the PHM has a simple
probabilistic interpretation, indicating the origins and destinations of
electrons and holes and, hence, the roles of different functional units of
molecules during an excitation. We present a formal derivation of the PHM,
starting from the particle-hole transition density matrix and projecting onto a
set of single-particle orbitals. We implement the PHM using atom-centered
localized basis sets and discuss the example of the molecular charge-transfer
complex $\rm C_2H_4 - C_2F_4$.


title:
Two holes in a two-dimensional quantum antiferromagnet: A variational
  study based on entangled-plaquette states

abstract:
  We show that the entangled-plaquette variational ansatz can be adapted to
study the two-dimensional $t-J$ model in the presence of two mobile holes.
Specifically, we focus on a square lattice comprising up to $N=256$ sites in
the parameter range $0.4\leq J/ t\leq2.0$. Ground state energies are obtained
via the optimization of a wave function in which the weight of a given
configuration is expressed in terms of variational coefficients associated with
square and linear entangled plaquettes. Our estimates are in excellent
agreement with exact results available for the $N=16$ lattice. By extending our
study to considerably larger systems we find, based on the analysis of the long
distance tail of the probability of finding two holes at spatial separation
$r$, and on our computed two-hole binding energies, the existence of a two-hole
bound state for all the values of $J/t$ explored here. It is estimated that
d-wave binding of the two holes does not occur for $J/t<J_c/t\simeq 0.19$.


title: Enumerating quasi-Yamanouchi tableaux of Durfee size two

abstract:
  Quasi-Yamanouchi tableaux connect the two most studied types of tableaux.
They are a subset of semistandard Young tableaux that are also a refinement on
standard Young tableaux, and they can be used to improve the fundamental
quasisymmetric expansion of Schur polynomials. We prove a product formula for
enumerating certain quasi-Yamanouchi tableaux and provide strong evidence that
no product formula exists in general for other shapes. Along the way, we also
prove some nice properties of their distribution and symmetry.


title: Stability of Geodesically Complete Cosmologies

abstract:
  We study the stability of spatially flat FRW solutions which are geodesically
complete, i.e. for which one can follow null (graviton) geodesics both in the
past and in the future without ever encountering singularities. This is the
case of NEC-violating cosmologies such as smooth bounces or solutions which
approach Minkowski in the past. We study the EFT of linear perturbations around
a solution of this kind, including the possibility of multiple fields and
fluids. One generally faces a gradient instability which can be avoided only if
the operator $~^{(3)}{R} \delta N~$ is present and its coefficient changes sign
along the evolution. This operator (typical of beyond-Horndeski theories) does
not lead to extra degrees of freedom, but cannot arise starting from any theory
with second-order equations of motion. The change of sign of this operator
prevents to set it to zero with a generalised disformal transformation.


title: Disk formation in oblate B[e] stars

abstract:
  We investigate the possible role of line-driven winds in the circumstellar
envelope in B[e] stars, mainly the role of the $\Omega$-slow wind solution,
which is characterized by a slower terminal velocity and higher mass-loss rate,
in comparison with the standard (m-CAK) wind solution. In this work, we assume
two scenarios: 1) a spherically symmetric star and 2) a scenario that considers
the oblate shape, considering only the oblate correction factor. For certain
values of the line force parameters (according to previous works), we obtain in
both scenarios a density contrast $\gtrsim10^{2}$ between equatorial and polar
densities, characterized for a fast polar wind and a slow and denser wind when
the $\Omega$-slow wind solution is obtained. All this properties are enhanced
when the oblate correction factor is included in our calculations.


title: Is Left-Right Symmetry the Key?

abstract:
  In collaboration with Jogesh Pati, Abdus Salam challenged the chiral gauge
nature of the Standard Model by paving the road towards the Left-Right
symmetric electro-weak theory. I describe here the logical and historical
construction of this theory, by emphasising the pioneering and key role it
played for neutrino mass. I show that it is a self-contained and predictive
model with the Higgs origin of Majorana neutrino mass, in complete analogy with
the SM situation regarding charged fermions.


title:
Phase Retrieval Meets Statistical Learning Theory: A Flexible Convex
  Relaxation

abstract:
  We propose a flexible convex relaxation for the phase retrieval problem that
operates in the natural domain of the signal. Therefore, we avoid the
prohibitive computational cost associated with "lifting" and semidefinite
programming (SDP) in methods such as PhaseLift and compete with recently
developed non-convex techniques for phase retrieval. We relax the quadratic
equations for phaseless measurements to inequality constraints each of which
representing a symmetric "slab". Through a simple convex program, our proposed
estimator finds an extreme point of the intersection of these slabs that is
best aligned with a given anchor vector. We characterize geometric conditions
that certify success of the proposed estimator. Furthermore, using classic
results in statistical learning theory, we show that for random measurements
the geometric certificates hold with high probability at an optimal sample
complexity. Phase transition of our estimator is evaluated through simulations.
Our numerical experiments also suggest that the proposed method can solve phase
retrieval problems with coded diffraction measurements as well.

categories: cs.IT cs.LG math.FA math.IT math.OC stat.ML


title: Gated End-to-End Memory Networks

abstract:
  Machine reading using differentiable reasoning models has recently shown
remarkable progress. In this context, End-to-End trainable Memory Networks,
MemN2N, have demonstrated promising performance on simple natural language
based reasoning tasks such as factual reasoning and basic deduction. However,
other tasks, namely multi-fact question-answering, positional reasoning or
dialog related tasks, remain challenging particularly due to the necessity of
more complex interactions between the memory and controller modules composing
this family of models. In this paper, we introduce a novel end-to-end memory
access regulation mechanism inspired by the current progress on the connection
short-cutting principle in the field of computer vision. Concretely, we develop
a Gated End-to-End trainable Memory Network architecture, GMemN2N. From the
machine learning perspective, this new capability is learned in an end-to-end
fashion without the use of any additional supervision signal which is, as far
as our knowledge goes, the first of its kind. Our experiments show significant
improvements on the most challenging tasks in the 20 bAbI dataset, without the
use of any domain knowledge. Then, we show improvements on the dialog bAbI
tasks including the real human-bot conversion-based Dialog State Tracking
Challenge (DSTC-2) dataset. On these two datasets, our model sets the new state
of the art.


title: Ewens sampling and invariable generation

abstract:
  We study the number of random permutations needed to invariably generate the
symmetric group, $S_n$, when the distribution of cycle counts has the strong
$\alpha$-logarithmic property. The canonical example is the Ewens sampling
formula, for which the number of $k$-cycles relates to a conditioned Poisson
random variable with mean $\alpha/k$. The special case $\alpha =1$ corresponds
to uniformly random permutations, for which it was recently shown that exactly
four are needed. For strong $\alpha$-logarithmic measures, and almost every
$\alpha$, we show that precisely $\left\lceil ( 1- \alpha \log 2 )^{-1}
\right\rceil$ permutations are needed to invariably generate $S_n$. A corollary
is that for many other probability measures on $S_n$ no bounded number of
permutations will invariably generate $S_n$ with positive probability. Along
the way we generalize classic theorems of Erd\H{o}s, Tehran, Pyber, Luczak and
Bovey to permutations obtained from the Ewens sampling formula.


title: Reset-free Trial-and-Error Learning for Robot Damage Recovery

abstract:
  The high probability of hardware failures prevents many advanced robots
(e.g., legged robots) from being confidently deployed in real-world situations
(e.g., post-disaster rescue). Instead of attempting to diagnose the failures,
robots could adapt by trial-and-error in order to be able to complete their
tasks. In this situation, damage recovery can be seen as a Reinforcement
Learning (RL) problem. However, the best RL algorithms for robotics require the
robot and the environment to be reset to an initial state after each episode,
that is, the robot is not learning autonomously. In addition, most of the RL
methods for robotics do not scale well with complex robots (e.g., walking
robots) and either cannot be used at all or take too long to converge to a
solution (e.g., hours of learning). In this paper, we introduce a novel
learning algorithm called "Reset-free Trial-and-Error" (RTE) that (1) breaks
the complexity by pre-generating hundreds of possible behaviors with a dynamics
simulator of the intact robot, and (2) allows complex robots to quickly recover
from damage while completing their tasks and taking the environment into
account. We evaluate our algorithm on a simulated wheeled robot, a simulated
six-legged robot, and a real six-legged walking robot that are damaged in
several ways (e.g., a missing leg, a shortened leg, faulty motor, etc.) and
whose objective is to reach a sequence of targets in an arena. Our experiments
show that the robots can recover most of their locomotion abilities in an
environment with obstacles, and without any human intervention.


title: Quantum non-malleability and authentication

abstract:
  In encryption, non-malleability is a highly desirable property: it ensures
that adversaries cannot manipulate the plaintext by acting on the ciphertext.
Ambainis, Bouda and Winter gave a definition of non-malleability for the
encryption of quantum data. In this work, we show that this definition is too
weak, as it allows adversaries to "inject" plaintexts of their choice into the
ciphertext. We give a new definition of quantum non-malleability which resolves
this problem. Our definition is expressed in terms of entropic quantities,
considers stronger adversaries, and does not assume secrecy. Rather, we prove
that quantum non-malleability implies secrecy; this is in stark contrast to the
classical setting, where the two properties are completely independent. For
unitary schemes, our notion of non-malleability is equivalent to encryption
with a two-design (and hence also to the definition of Ambainis et al.). Our
techniques also yield new results regarding the closely-related task of quantum
authentication. We show that "total authentication" (a notion recently proposed
by Garg, Yuen and Zhandry) can be satisfied with two-designs, a significant
improvement over the eight-design construction of Garg et al. We also show
that, under a mild adaptation of the rejection procedure, both total
authentication and our notion of non-malleability yield quantum authentication
as defined by Dupuis, Nielsen and Salvail.


title: Partial Strong Converse for the Non-Degraded Wiretap Channel

abstract:
  We prove the partial strong converse property for the discrete memoryless
\emph{non-degraded} wiretap channel, for which we require the leakage to the
eavesdropper to vanish but allow an asymptotic error probability $\epsilon \in
[0,1)$ to the legitimate receiver. We show that when the transmission rate is
above the secrecy capacity, the probability of correct decoding at the
legitimate receiver decays to zero exponentially. Therefore, the maximum
transmission rate is the same for $\epsilon \in [0,1)$, and the partial strong
converse property holds. Our work is inspired by a recently developed technique
based on information spectrum method and Chernoff-Cramer bound for evaluating
the exponent of the probability of correct decoding.


title:
Soliton solutions in two-dimensional Lorentz-violating higher derivative
  scalar theory

abstract:
  This paper shows a new approach to obtain analytical topological defects of a
2D Myers-Pospelov Lagrangian for two scalar fields. Such a Lagrangian presents
higher-order kinetic terms, which lead us to equations of motion which are
non-trivial to be integrated. Here we describe three possible scenarios for the
equations of motion, named by timelike, spacelike and lightlike respectively.
We started our investigation with a kink-like travelling wave Ansatz for the
free theory, which led us to constraints for the dispersion relations of each
scenario. We also introduced a procedure to obtain analytical solutions for the
general theory in the three mentioned scenarios. We exemplified the procedure
and discussed the behavior of the defect solutions carefully. It is remarkable
that the methodology presented in this study led to analytical models, despite
the complexity of the equations of motion derived from the 2D Myers-Pospelov
Lagrangian. The methodology here tailored can be applied to several Lagrangians
with higher-order derivative terms.


title: Greed is Good for Deterministic Scale-Free Networks

abstract:
  Large real-world networks typically follow a power-law degree distribution.
To study such networks, numerous random graph models have been proposed.
However, real-world networks are not drawn at random. Therefore, Brach, Cygan,
{\L}acki, and Sankowski [SODA 2016] introduced two natural deterministic
conditions: (1) a power-law upper bound on the degree distribution (PLB-U) and
(2) power-law neighborhoods, that is, the degree distribution of neighbors of
each vertex is also upper bounded by a power law (PLB-N). They showed that many
real-world networks satisfy both deterministic properties and exploit them to
design faster algorithms for a number of classical graph problems.
  We complement the work of Brach et al. by showing that some well-studied
random graph models exhibit both the mentioned PLB properties and additionally
also a power-law lower bound on the degree distribution (PLB-L). All three
properties hold with high probability for Chung-Lu Random Graphs and Geometric
Inhomogeneous Random Graphs and almost surely for Hyperbolic Random Graphs. As
a consequence, all results of Brach et al. also hold with high probability or
almost surely for those random graph classes.
  In the second part of this work we study three classical NP-hard
combinatorial optimization problems on PLB networks. It is known that on
general graphs with maximum degree {\Delta}, a greedy algorithm, which chooses
nodes in the order of their degree, only achieves an {\Omega}(ln
{\Delta})-approximation for Minimum Vertex Cover and Minimum Dominating Set,
and an {\Omega}({\Delta})-approximation for Maximum Independent Set. We prove
that the PLB-U property suffices for the greedy approach to achieve a
constant-factor approximation for all three problems. We also show that all
three combinatorial optimization problems are APX-complete, even if all
PLB-properties hold.


title: Super-Resolution Delay-Doppler Estimation for OFDM Passive Radar

abstract:
  In this paper, we consider the problem of joint delay-Doppler estimation of
moving targets in a passive radar that makes use of orthogonal
frequency-division multiplexing (OFDM) communication signals. A compressed
sensing algorithm is proposed to achieve supper-resolution and better accuracy,
using both the atomic norm and the $\ell_1$-norm. The atomic norm is used to
manifest the signal sparsity in the continuous domain. Unlike previous works
which assume the demodulation to be error free, we explicitly introduce the
demodulation error signal whose sparsity is imposed by the $\ell_1$-norm. On
this basis, the delays and Doppler frequencies are estimated by solving a
semidefinite program (SDP) which is convex. We also develop an iterative method
for solving this SDP via the alternating direction method of multipliers (ADMM)
where each iteration involves closed-form computation. Simulation results are
presented to illustrate the high performance of the proposed algorithm.