title: Rescaled bipartite planar maps converge to the Brownian map

abstract:
  For every integer $n\geq 1$, we consider a random planar map $\mathcal{M}_n$
which is uniformly distributed over the class of all rooted bipartite planar
maps with $n$ edges. We prove that the vertex set of $\mathcal{M}_n$ equipped
with the graph distance rescaled by the factor $(2n)^{-1/4}$ converges in
distribution, in the Gromov-Hausdorff sense, to the Brownian map. This
complements several recent results giving the convergence of various classes of
random planar maps to the Brownian map.


title: Gevrey regularity for the supercritical quasi-geostrophic equation

abstract:
  In this paper, following the techniques of Foias and Temam, we establish
suitable Gevrey class regularity of solutions to the supercritical
quasi-geostrophic equations in the whole space, with initial data in "critical"
Sobolev spaces. Moreover, the Gevrey class that we obtain is "near optimal" and
as a corollary, we obtain temporal decay rates of higher order Sobolev norms of
the solutions. Unlike the Navier-Stokes or the subcritical quasi-geostrophic
equations, the low dissipation poses a difficulty in establishing Gevrey
regularity. A new commutator estimate in Gevrey classes, involving the dyadic
Littlewood-Paley operators, is established that allow us to exploit the
cancellation properties of the equation and circumvent this difficulty.


title:
Coupling between corotation and Lindblad resonances in the elliptic
  planar three-body problem

abstract:
  We investigate the dynamics of two satellites with masses $\mu_s$ and
$\mu'_s$ orbiting a massive central planet in a common plane, near a first
order mean motion resonance $m$+1:$m$ ($m$ integer). We consider only the
resonant terms of first order in eccentricity in the disturbing potential of
the satellites, plus the secular terms causing the orbital apsidal precessions.
We obtain a two-degree of freedom system, associated with the two critical
resonant angles $\phi= (m+1)\lambda' -m\lambda - \varpi$ and $\phi'=
(m+1)\lambda' -m\lambda - \varpi'$, where $\lambda$ and $\varpi$ are the mean
longitude and longitude of periapsis of $\mu_s$, respectively, and where the
primed quantities apply to $\mu'_s$. We consider the special case where $\mu_s
\rightarrow 0$ (restricted problem). The symmetry between the two angles $\phi$
and $\phi'$ is then broken, leading to two different kinds of resonances,
classically referred to as Corotation Eccentric resonance (CER) and Lindblad
Eccentric Resonance (LER), respectively. We write the four reduced equations of
motion near the CER and LER, that form what we call the CoraLin model. This
model depends upon only two dimensionless parameters that control the dynamics
of the system: the distance $D$ between the CER and LER, and a forcing
parameter $\epsilon_L$ that includes both the mass and the orbital eccentricity
of the disturbing satellite. Three regimes are found: for $D=0$ the system is
integrable, for $D$ of order unity, it exhibits prominent chaotic regions,
while for $D$ large compared to 2, the behavior of the system is regular and
can be qualitatively described using simple adiabatic invariant arguments. We
apply this model to three recently discovered small Saturnian satellites
dynamically linked to Mimas through first order mean motion resonances :
Aegaeon, Methone and Anthe.


title: Walk dimension for light in complex disordered media

abstract:
  Transport in complex systems is characterized by a fractal dimension -- the
walk dimension -- that indicates the diffusive or anomalous nature of the
underlying random walk process. Here we report on the experimental retrieval of
this key quantity, using light waves propagating in disordered media. The
approach is based on measurements of the time-resolved transmission, in
particular on how the lifetime scales with sample size. We show that this
allows one to retrieve the walk dimension and apply the concept to samples with
varying degree of fractal heterogeneity. In addition, the method provides the
first experimental demonstration of anomalous light dynamics in a random
medium.

categories: physics.optics cond-mat.dis-nn cond-mat.mes-hall cond-mat.stat-mech


title:
Differential atom interferometry with $^{87}$Rb and $^{85}$Rb for
  testing the UFF in STE-QUEST

abstract:
  In this paper we discuss in detail an experimental scheme to test the
universality of free fall (UFF) with a differential $^{87}$Rb / $^{85}$Rb atom
interferometer applicable for extended free fall of several seconds in the
frame of the STE-QUEST mission. This analysis focuses on suppression of noise
and error sources which would limit the accuracy of a violation measurement. We
show that the choice of atomic species and the correctly matched parameters of
the interferometer sequence are of utmost importance to suppress leading order
phase shifts. In conclusion we will show the expected performance of $2$ parts
in $10^{15}$ of such an interferometer for a test of the UFF.


title:
Comment on "Gradient Dynamics Description for Films of Mixtures and
  Suspensions: Dewetting Triggered by Coupled Film Height and Concentration
  Fluctuations"

abstract:
  We discuss a recent effort in the modelling of binary component thin films,
which yielded the same conclusions and stability limits as earlier work,
despite a different method of incorporating constraints into the gradient
dynamics description of the system.


title:
Standing Swells Surveyed Showing Surprisingly Stable Solutions for the
  Lorenz '96 Model

abstract:
  The Lorenz '96 model is an adjustable dimension system of ODEs exhibiting
chaotic behavior representative of dynamics observed in the Earth's atmosphere.
In the present study, we characterize statistical properties of the chaotic
dynamics while varying the degrees of freedom and the forcing. Tuning the
dimensionality of the system, we find regions of parameter space with
surprising stability in the form of standing waves traveling amongst the slow
oscillators. The boundaries of these stable regions fluctuate regularly with
the number of slow oscillators. These results demonstrate hidden order in the
Lorenz '96 system, strengthening the evidence for its role as a hallmark
representative of nonlinear dynamical behavior.


title:
The electron-phonon relaxation time in thin superconducting titanium
  nitride films

abstract:
  We report on the direct measurement of the electron-phonon relaxation time,
{\tau}eph, in disordered TiN films. Measured values of {\tau}eph are from 5.5
ns to 88 ns in the 4.2 to 1.7 K temperature range and consistent with a T-3
temperature dependence. The electronic density of states at the Fermi level N0
is estimated from measured material parameters. The presented results confirm
that thin TiN films are promising candidate-materials for ultrasensitive
superconducting detectors.


title:
Generalized beta convolution model of the true intensity for the
  Illumina BeadArrays

abstract:
  Microarray data come from many steps of production and have been known to
contain noise. The pre-processing is implemented to reduce the noise, where the
background is corrected. Prior to further analysis, many Illumina BeadArrays
users had applied the convolution model, a model which had been adapted from
when it was first developed on the Affymetrix platform, to adjust the intensity
value: corrected background intensity value.
  Several models based on different underlying distributions and or parameters
estimation methods have been proposed and applied. For instance : the
exponential-gamma, the normal-gamma and the exponential-normal convolutions
with a maximum likelihood estimation, non-parametric, Bayesian and moment
methods of the parameters estimation, including two recent
exponential-lognormal and gamma-lognormal convolutions.
  In this paper, we propose models and derive the corrected background
intensity based on the generalized betas and the generalized beta-normal
convolutions as a generalization of the existing models.


title:
From Theory to Observations and viceversa: theoretical uncertainties and
  observational constraints

abstract:
  During these last decades, our knowledge of evolutionary and structural
properties of stars of different mass and chemical composition is significantly
improved. This result has been achieved as a consequence of our improved
capability in understanding and describing the physical behavior of matter in
the different thermal regimes characteristic of the various stellar mass ranges
and evolutionary stages. This notwithstanding, current generation of stellar
models is still affected by significant and, usually, not negligible
uncertainties. These uncertainties are related to our poor knowledge of some
physical proceses occurring in the real stars such as, for instance, some
thermodynamical processes, nuclear reaction rates, as well as the efficiency of
mixing processes. These drawbacks of stellar models have to be properly taken
into account when comparing theory with observations in order to derive
relevant information about the properties of both resolved and unresolved
stellar populations. On the other hand, observations of both field and cluster
stars can provide fundamental benchmarks for constraining the reliability and
accuracy of the theoretical framework. In the following we review some
important evolutionary and structural properties of very-low and low-mass
stars, as well as the most important uncertainties affecting the stellar models
for such stars. We show what are the main sources of uncertainty along the main
evolutionary stages, and discuss the present level of agreement between theory
and observations.


title: Dissipative conformal measures on locally compact spaces

abstract:
  The paper introduces a general method to construct conformal measures for a
local homeomorphism on a locally compact non-compact Hausdorff space, subject
to mild irreducibility-like conditions. Among others the method is used to give
necessary and sufficient conditions for the existence of eigenmeasures for the
dual Ruelle operator associated to a locally compact non-compact irreducible
Markov shift equipped with a uniformly continuous potential function. As an
application to operator algebras the results are used to determine for which
$\beta$ there are gauge invariant $\beta$-KMS weights on a simple graph
$C^*$-algebra when the one-parameter automorphism group is given by a uniformly
continuous real-valued function on the path space of the graph.


title:
Optimal conditions for the numerical calculation of the largest Lyapunov
  exponent for systems of ordinary differential equations

abstract:
  A general indicator of the presence of chaos in a dynamical system is the
largest Lyapunov exponent. This quantity provides a measure of the mean
exponential rate of divergence of nearby orbits. In this paper, we show that
the so-called two-particle method introduced by Benettin et al. could lead to
spurious estimations of the largest Lyapunov exponent. As a comparator method,
the maximum Lyapunov exponent is computed from the solution of the variational
equations of the system. We show that the incorrect estimation of the largest
Lyapunov exponent is based on the setting of the renormalization time and the
initial distance between trajectories. Unlike previously published works, we
here present three criteria that could help to determine correctly these
parameters so that the maximum Lyapunov exponent is close to the expected
value. The results have been tested with four well known dynamical systems:
Ueda, Duffing, R\"ossler and Lorenz.


title:
Conductance fingerprint of Majorana fermions in the topological Kondo
  effect

abstract:
  We consider an interacting nanowire/superconductor heterostructure attached
to metallic leads. The device is described by an unusual low-energy model
involving spin-1 conduction electrons coupled to a nonlocal spin-1/2 Kondo
impurity built from Majorana fermions. The topological origin of the resulting
Kondo effect is manifest in distinctive non-Fermi-liquid (NFL) behavior, and
the existence of Majorana fermions in the device is demonstrated unambiguously
by distinctive conductance lineshapes. We study the physics of the model in
detail, using the numerical renormalization group, perturbative scaling and
abelian bosonization. In particular, we calculate the full scaling curves for
the differential conductance in AC and DC fields, onto which experimental data
should collapse. Scattering t-matrices and thermodynamic quantities are also
calculated, recovering asymptotes from conformal field theory. We show that the
NFL physics is robust to asymmetric Majorana-lead couplings, and here we
uncover a duality between strong and weak coupling. The NFL behavior is
understood physically in terms of competing Kondo effects. The resulting
frustration is relieved by inter-Majorana coupling which generates a second
crossover to a regular Fermi liquid.


title: A Comprehensive Analysis of Polyhedral Lift-and-Project Methods

abstract:
  We consider lift-and-project methods for combinatorial optimization problems
and focus mostly on those lift-and-project methods which generate polyhedral
relaxations of the convex hull of integer solutions. We introduce many new
variants of Sherali--Adams and Bienstock--Zuckerberg operators. These new
operators fill the spectrum of polyhedral lift-and-project operators in a way
which makes all of them more transparent, easier to relate to each other, and
easier to analyze. We provide new techniques to analyze the worst-case
performances as well as relative strengths of these operators in a unified way.
In particular, using the new techniques and a result of Mathieu and Sinclair
from 2009, we prove that the polyhedral Bienstock--Zuckerberg operator requires
at least $\sqrt{2n}- \frac{3}{2}$ iterations to compute the matching polytope
of the $(2n+1)$-clique. We further prove that the operator requires
approximately $\frac{n}{2}$ iterations to reach the stable set polytope of the
$n$-clique, if we start with the fractional stable set polytope. Lastly, we
show that some of the worst-case instances for the positive semidefinite
Lov\'asz--Schrijver lift-and-project operator are also bad instances for the
strongest variants of the Sherali--Adams operator with positive semidefinite
strengthenings, and discuss some consequences for integrality gaps of convex
relaxations.


title: Examples of toric manifolds which are not quasitoric manifolds

abstract:
  We construct toric manifolds of complex dimension $\geq 4$, whose orbit
spaces by the action of the compact torus are not homeomorphic to simple
polytopes (as manifolds with corners). These provide the first known examples
of toric manifolds which are not quasitoric manifolds.


title: Aspects of duality in gravitational theories

abstract:
  This thesis is divided in two parts. The first part contains the study of
some properties of the electromagnetic duality in 4 dimensions. An extended
double potential formalism for linearized gravity is introduced which allows to
write an action manifestly invariant under duality rotations in presence of
both electric and magnetic external sources. It is also shown how, in the
reduced phase-space, all higher spin gauge fields can be written as
bi-hamiltonian systems. The role of the second hamiltonian is played by the
electromagnetic duality generator. The second part is devoted to the study of
asymptotic symmetries and their applications to holography. After a review of
symmetries and classical solutions involved in the AdS3/CFT2 correspondence, we
apply a similar analysis to asymptotically flat spacetimes at null infinity in
3 and 4 dimensions. In particular, it is argued that the symmetry algebra of
asymptotically flat spacetimes at null infinity in 4 dimensions should be taken
as the semi-direct sum of supertranslations with infinitesimal local conformal
transformations and not, as usually done, with the Lorentz algebra. The first
applications are studied: an exact representation by bulk vector fields of the
asymptotic symmetry algebra through the introduction of a modified Lie bracket,
the derivation of how this symmetry algebra is realized on solution space and
the construction of the associated centrally extended surface charge algebra.


title:
Tables of E2 Transition Probabilities from the first $2^{+}$ States in
  Even-Even Nuclei

abstract:
  Experimental results of E2 transition probabilities or B(E2) values for the
known first 2$^{+}$ states in 447 even-even nuclei have been compiled and
evaluated. The evaluation policies for the analysis of experimental data have
been described and new results are discussed. The recommended B(E2) values have
been compared with comprehensive shell model calculations for a selected set of
nuclei, where such theoretical procedures are amenable. The present work was
motivated by a rapid increase in the number of new B(E2) measurements for the
first 2$^{+}$ states since the previous evaluation of such data by S. Raman
{\it et al.} published in 2001. Future plans to investigate the systematics of
B(E2)$\uparrow$ values, and intercomparison of different experimental
techniques to obtain these data are outlined.


title: Resolution of type IV singularities in quantum cosmology

abstract:
  We discuss the fate of classical type IV singularities in quantum cosmology.
The framework is Wheeler-DeWitt quantization applied to homogeneous and
isotropic universes with a perfect fluid described by a generalized Chaplygin
gas. Such a fluid can be dynamically realized by a scalar field. We treat the
cases of a standard scalar field with positive kinetic energy and of a scalar
field with negative energy (phantom field). We first present the classical
solutions. We then discuss in detail the Wheeler-DeWitt equation for these
models. We are able to give analytic solutions for a special case and to draw
conclusions for the general case. Adopting the criterion that singularities are
avoided if the wave function vanishes in the region of the classical
singularity, we find that type IV singularities are avoided only for particular
solutions of the Wheeler-DeWitt equation. We compare this result with earlier
results found for other types of singularities.


title:
Asymmetric random walks in a discrete spacetime as a model for quantum
  mechanics

abstract:
  This paper presents a simple model that mimics quantum mechanics (QM) results
in terms of probability fields of free particles subject to self-interference,
without using Schr\"{o}dinger equation or wavefunctions. Unlike the standard QM
picture, the proposed model only uses integer-valued quantities and arithmetic
operations. In particular, it assumes a discrete spacetime under the form of an
euclidean lattice. The proposed approach describes individual particle
trajectories as random walks. Transition probabilities are simple functions of
a few quantities that are either randomly associated to the particles during
their preparation, or stored in the lattice sites they visit during the walk.
Non-relativistic QM predictions, particularly self-interference, are retrieved
as probability distributions of similarly-prepared ensembles of particles.
Extension to interacting particles is discussed but not detailed in this paper.


title:
Superpolynomial lower bounds for general homogeneous depth 4 arithmetic
  circuits

abstract:
  In this paper, we prove superpolynomial lower bounds for the class of
homogeneous depth 4 arithmetic circuits. We give an explicit polynomial in VNP
of degree $n$ in $n^2$ variables such that any homogeneous depth 4 arithmetic
circuit computing it must have size $n^{\Omega(\log \log n)}$.
  Our results extend the works of Nisan-Wigderson [NW95] (which showed
superpolynomial lower bounds for homogeneous depth 3 circuits),
Gupta-Kamath-Kayal-Saptharishi and Kayal-Saha-Saptharishi [GKKS13, KSS13]
(which showed superpolynomial lower bounds for homogeneous depth 4 circuits
with bounded bottom fan-in), Kumar-Saraf [KS13a] (which showed superpolynomial
lower bounds for homogeneous depth 4 circuits with bounded top fan-in) and
Raz-Yehudayoff and Fournier-Limaye-Malod-Srinivasan [RY08, FLMS13] (which
showed superpolynomial lower bounds for multilinear depth 4 circuits). Several
of these results in fact showed exponential lower bounds.
  The main ingredient in our proof is a new complexity measure of {\it bounded
support} shifted partial derivatives. This measure allows us to prove
exponential lower bounds for homogeneous depth 4 circuits where all the
monomials computed at the bottom layer have {\it bounded support} (but possibly
unbounded degree/fan-in), strengthening the results of Gupta et al and Kayal et
al [GKKS13, KSS13]. This new lower bound combined with a careful "random
restriction" procedure (that transforms general depth 4 homogeneous circuits to
depth 4 circuits with bounded support) gives us our final result.


title: Some recent research directions in the computably enumerable sets

abstract:
  As suggested by the title, this paper is a survey of recent results and
questions on the collection of computably enumerable sets under inclusion. This
is not a broad survey but one focused on the author's and a few others' current
research.


title:
STE-QUEST - Test of the Universality of Free Fall Using Cold Atom
  Interferometry

abstract:
  The theory of general relativity describes macroscopic phenomena driven by
the influence of gravity while quantum mechanics brilliantly accounts for
microscopic effects. Despite their tremendous individual success, a complete
unification of fundamental interactions is missing and remains one of the most
challenging and important quests in modern theoretical physics. The STE-QUEST
satellite mission, proposed as a medium-size mission within the Cosmic Vision
program of the European Space Agency (ESA), aims for testing general relativity
with high precision in two experiments by performing a measurement of the
gravitational redshift of the Sun and the Moon by comparing terrestrial clocks,
and by performing a test of the Universality of Free Fall of matter waves in
the gravitational field of Earth comparing the trajectory of two Bose-Einstein
condensates of Rb85 and Rb87. The two ultracold atom clouds are monitored very
precisely thanks to techniques of atom interferometry. This allows to reach
down to an uncertainty in the E\"otv\"os parameter of at least 2x10E-15. In
this paper, we report about the results of the phase A mission study of the
atom interferometer instrument covering the description of the main payload
elements, the atomic source concept, and the systematic error sources.

categories: quant-ph gr-qc physics.atom-ph physics.space-ph


title: Weak gravitational lensing

abstract:
  Luminous tracers have been used extensively to map the large-scale matter
distribution in the Universe. Similarly the dynamics of stars or galaxies can
be used to estimate masses of galaxies and clusters of galaxies. However,
assumptions need to be made about the dynamical state or how well galaxies
trace the underlying dark matter distribution. The gravitational tidal field
affects the paths of photons, leading to observable effects. This phenomenon,
gravitational lensing, has become an important tool in cosmology because it
probes the mass distribution directly. In these lecture notes we introduce the
main relevant quantities and terminology, but the subsequent discussion is
mostly limited to weak gravitational lensing, the small coherent distortion of
the shapes of distant galaxies by intervening structures. We focus on some of
the issues in measuring accurate shapes and review the various applications of
weak gravitational lensing, as well as some recent results.


title: A Rare Encounter with Very Massive Stars in NGC 3125-A1

abstract:
  Super star cluster A1 in the nearby starburst galaxy NGC 3125 is
characterized by broad He\ii \lam1640 emission (full width at half maximum,
$FWHM\sim1200$ km s$^{-1}$) of unprecedented strength (equivalent width,
$EW=7.1\pm0.4$ \AA). Previous attempts to characterize the massive star content
in NGC 3125-A1 were hampered by the low resolution of the UV spectrum and the
lack of co-spatial panchromatic data. We obtained far-UV to near-IR
spectroscopy of the two principal emitting regions in the galaxy with the Space
Telescope Imaging Spectrograph (STIS) and the Cosmic Origins Spectrograph (COS)
onboard the Hubble Space Telescope (\hst). We use these data to study three
clusters in the galaxy, A1, B1, and B2. We derive cluster ages of 3-4 Myr,
intrinsic reddenings of $E(B-V)=0.13$, 0.15, and 0.13, and cluster masses of
$1.7\times10^5$, $1.4\times10^5$, and $1.1\times10^5$ M$_\odot$, respectively.
A1 and B2 show O\vb \lam1371 absorption from massive stars, which is rarely
seen in star-forming galaxies, and have Wolf-Rayet (WR) to O star ratios of
$N(WN5-6)/N(O)=0.23$ and 0.10, respectively. The high $N(WN5-6)/N(O)$ ratio of
A1 cannot be reproduced by models that use a normal IMF and generic WR star
line luminosities. We rule out that the extraordinary He\ii \lam1640 emission
and O\vb \lam1371 absorption of A1 are due to an extremely flat upper IMF
exponent, and suggest that they originate in the winds of very massive
($>120\,M_\odot$) stars. In order to reproduce the properties of peculiar
clusters such as A1, the present grid of stellar evolution tracks implemented
in Starburst99 needs to be extended to masses $>120\,M_\odot$.


title: Dynamics in atomic signaling games

abstract:
  We study an atomic signaling game under stochastic evolutionary dynamics.
There is a finite number of players who repeatedly update from a finite number
of available languages/signaling strategies. Players imitate the most fit
agents with high probability or mutate with low probability. We analyze the
long-run distribution of states and show that, for sufficiently small mutation
probability, its support is limited to efficient communication systems. We find
that this behavior is insensitive to the particular choice of evolutionary
dynamic, a property that is due to the game having a potential structure with a
potential function corresponding to average fitness. Consequently, the model
supports conclusions similar to those found in the literature on language
competition. That is, we show that efficient languages eventually predominate
the society while reproducing the empirical phenomenon of linguistic drift. The
emergence of efficiency in the atomic case can be contrasted with results for
non-atomic signaling games that establish the non-negligible possibility of
convergence, under replicator dynamics, to states of unbounded efficiency loss.


title: Non-Standard Finite-Size Scaling at First-Order Phase Transitions

abstract:
  We note that the standard inverse system volume scaling for finite-size
corrections at a first-order phase transition (i.e., 1/L^3 for an L x L x L
lattice in 3D) is transmuted to 1/L^2 scaling if there is an exponential
low-temperature phase degeneracy. The gonihedric Ising model which has a
four-spin interaction, plaquette Hamiltonian provides an exemplar of just such
a system. We use multicanonical simulations of this model to generate
high-precision data which provides strong confirmation of the non-standard
finite-size scaling law. The dual to the gonihedric model, which is an
anisotropically coupled Ashkin-Teller model, has a similar degeneracy and also
displays the non-standard scaling.

categories: cond-mat.stat-mech hep-lat math-ph math.MP


title: Learning Type-Driven Tensor-Based Meaning Representations

abstract:
  This paper investigates the learning of 3rd-order tensors representing the
semantics of transitive verbs. The meaning representations are part of a
type-driven tensor-based semantic framework, from the newly emerging field of
compositional distributional semantics. Standard techniques from the neural
networks literature are used to learn the tensors, which are tested on a
selectional preference-style task with a simple 2-dimensional sentence space.
Promising results are obtained against a competitive corpus-based baseline. We
argue that extending this work beyond transitive verbs, and to
higher-dimensional sentence spaces, is an interesting and challenging problem
for the machine learning community to consider.


title: Approximation in Sobolev spaces by piecewise affine interpolation

abstract:
  Functions in a Sobolev space are approximated directly by piecewise affine
interpolation in the norm of the space. The proof is based on estimates for
interpolations and does not rely on the density of smooth functions.


title:
Double transitivity of Galois Groups in Schubert Calculus of
  Grassmannians

abstract:
  We investigate double transitivity of Galois groups in the classical Schubert
calculus on Grassmannians. We show that all Schubert problems on Grassmannians
of 2- and 3-planes have doubly transitive Galois groups, as do all Schubert
problems involving only special Schubert conditions. We use these results to
give a new proof that Schubert problems on Grassmannians of 2-planes have
Galois groups that contain the alternating group. We also investigate the
Galois group of every Schubert problem on Gr(4,8), finding that each Galois
group either contains the alternating group or is an imprimitive permutation
group and therefore fails to be doubly transitive. These imprimitive examples
show that our results are the best possible general results on double
transitivity of Schubert problems.


title:
Strong solutions for the Beris-Edwards model for nematic liquid crystals
  with homogeneous Dirichlet boundary conditions

abstract:
  Existence and uniqueness of local strong solution for the Beris--Edwards
model for nematic liquid crystals, which couples the Navier-Stokes equations
with an evolution equation for the Q-tensor, is established on a bounded domain
in the case of homogeneous Dirichlet boundary conditions. The classical
Beris--Edwards model is enriched by including a dependence of the fluid
viscosity on the Q-tensor. The proof is based on a linearization of the system
and Banach's fixed-point theorem.


title:
Electronics with correlated oxides: SrVO$_3$/SrTiO$_3$ as a Mott
  transistor

abstract:
  We employ density functional theory plus dynamical mean field theory and
identify the physical origin of why two layers of SrVO$_3$ on a SrTiO$_3$
substrate are insulating: the thin film geometry lifts the orbital degeneracy
which in turn triggers a Mott-Hubbard transition. Two layers of SrVO$_3$ are
just at the verge of a Mott-Hubbard transition and hence ideally suited for
technological applications of the Mott-Hubbard transition: the heterostructure
is highly sensitive to strain, electric field, and temperature. A gate voltage
can also turn the insulator into a metal, so that a transistor with ideal
on-off (metal-insulator) switching properties is realized.


title:
Universal Polar Codes for More Capable and Less Noisy Channels and
  Sources

abstract:
  We prove two results on the universality of polar codes for source coding and
channel communication. First, we show that for any polar code built for a
source $P_{X,Z}$ there exists a slightly modified polar code - having the same
rate, the same encoding and decoding complexity and the same error rate - that
is universal for every source $P_{X,Y}$ when using successive cancellation
decoding, at least when the channel $P_{Y|X}$ is more capable than $P_{Z|X}$
and $P_X$ is such that it maximizes $I(X;Y) - I(X;Z)$ for the given channels
$P_{Y|X}$ and $P_{Z|X}$. This result extends to channel coding for discrete
memoryless channels. Second, we prove that polar codes using successive
cancellation decoding are universal for less noisy discrete memoryless
channels.


title: Metabelian associative algebras

abstract:
  Metabelian algebras are introduced and it is shown that an algebra $A$ is
metabelian if and only if $A$ is a nilpotent algebra having the index of
nilpotency at most $3$, i.e. $x y z t = 0$, for all $x$, $y$, $z$, $t \in A$.
We prove that the It\^{o}'s theorem for groups remains valid for associative
algebras. A structure theorem for metabelian algebras is given in terms of pure
linear algebra tools and their classification from the view point of the
extension problem is proven. Two border-line cases are worked out in detail:
all metabelian algebras having the derived algebra of dimension $1$ (resp.
codimension $1$) are explicitly described and classified. The algebras of the
first family are parameterized by bilinear forms and classified by their
homothetic relation. The algebras of the second family are parameterized by the
set of all matrices $(X, Y, u) \in {\rm M}_{n}(k)^2 \times k^n$ satisfying $X^2
= Y^2 = 0$, $XY = YX$ and $Xu = Yu$.


title: Feedback-Induced Steady-State Light Bunching Above the Lasing Threshold

abstract:
  We develop a full quantum-optical approach for optical self-feedback of a
microcavity laser. These miniaturized devices work in a regime between the
quantum and classical limit and are test-beds for the differences between a
quantized theory of optical self-feedback and the corresponding semiclassical
theory. The light intensity and photon statistics are investigated with and
without an external feedback: We show that in the low-gain limit, where
relaxation oscillations do not appear, the recently observed photon bunching in
a quantum dot microcavity laser with optical feedback can be accounted for only
by the fully quantized model. By providing a description of laser devices with
feedback in the quantum limit we reveal novel insights into the origin of
bunching in quantized and semiclassical models.


title: Superfluid two-stream instability in a microscopic model

abstract:
  The superflow in a superfluid is bounded from above by Landau's critical
velocity. Within a microscopic bosonic model, I show that below this critical
velocity there is a dynamical instability that manifests itself in an imaginary
sound velocity and that is reminiscent of the two-stream instability in
electromagnetic plasmas. I compute the onset of this instability and its full
angular structure in a relativistic, uniform superfluid for all temperatures.
At weak coupling, the instability only operates in a very small region in the
phase diagram of temperature and superflow. Varying the coupling of the model
suggests that the effect is more prominent at strong coupling and thus could be
important for superfluids in compact stars and in the laboratory.


title: FeLoBAL Outflow Variability Constraints from Multi-Year Observations

abstract:
  The physical properties and dynamical behavior of Broad Absorption Line (BAL)
outflows are crucial themes in understanding the connections between galactic
centers and their hosts. FeLoBALs (identified with the presence of
low-ionization Fe II BALs) are a peculiar class of quasar outflows that
constitute approximately 1% of the BAL population. With their large column
densities and apparent outflow kinetic luminosities, FeLoBALs appear to be
exceptionally powerful and are strong candidates for feedback in galaxy
evolution. We conducted variability studies of 12 FeLoBAL quasars with emission
redshifts between 0.69 and 1.93, spanning both weekly and multi-year timescales
in the quasar's rest frame. We detected absorption-line variability from
low-ionization species (Fe II, Mg II) in four of our objects, with which we
established a representative upper limit for the distance of the absorber from
the supermassive black hole (SMBH) to be approximately 20 parsecs. Our goals
are to understand the mechanisms producing the variability (e.g. ionization
changes or gas traversing our line of sight) and place new constraints on the
locations, structure, and kinetic energies of the outflows.


title:
Experimental protocol for high-fidelity heralded photon-to-atom quantum
  state transfer

abstract:
  A quantum network combines the benefits of quantum systems regarding secure
information transmission and calculational speed-up by employing quantum
coherence and entanglement to store, transmit, and process information. A
promising platform for implementing such a network are atom-based quantum
memories and processors, interconnected by photonic quantum channels. A crucial
building block in this scenario is the conversion of quantum states between
single photons and single atoms through controlled emission and absorption.
Here we present an experimental protocol for photon-to-atom quantum state
conversion, whereby the polarization state of an absorbed photon is mapped onto
the spin state of a single absorbing atom with >95% fidelity, while successful
conversion is heralded by a single emitted photon. Heralded high-fidelity
conversion without affecting the converted state is a main experimental
challenge, in order to make the transferred information reliably available for
further operations. We record >80/s successful state transfer events out of
18,000/s repetitions.


title: Distribution of Powers Modulo 1 and Related Topics

abstract:
  This is a review of several results related to distribution of powers and
combination of powers modulo 1. We include a proof that given a sequence of
real numbers $\theta_n$, it is possible to get an $\alpha$ (given $\lambda \ne
0$), or a $\lambda$ (given $\alpha > 1$) such that $\lambda \alpha^n$ is close
to $\theta_n$ modulo 1. We also prove that in a number field, if a combination
of powers $\lambda_1 \alpha_1^n + \cdots + \lambda_m \alpha_m^n$ has bounded
$v$-adic absolute value (where $v$ is any non-Archimedian place) for $n \geq
n_0$, then the $\alpha_i$'s are algebraic integers. Finally we present several
open problem and topics for further research.


title:
Attractive forces in microporous carbon electrodes for capacitive
  deionization

abstract:
  The recently developed modified Donnan (mD) model provides a simple and
useful description of the electrical double layer in microporous carbon
electrodes, suitable for incorporation in porous electrode theory. By
postulating an attractive excess chemical potential for each ion in the
micropores that is inversely proportional to the total ion concentration, we
show that experimental data for capacitive deionization (CDI) can be accurately
predicted over a wide range of applied voltages and salt concentrations. Since
the ion spacing and Bjerrum length are each comparable to the micropore size
(few nm), we postulate that the attraction results from fluctuating bare
Coulomb interactions between individual ions and the metallic pore surfaces
(image forces) that are not captured by meanfield theories, such as the
Poisson-Boltzmann-Stern model or its mathematical limit for overlapping double
layers, the Donnan model. Using reasonable estimates of the micropore
permittivity and mean size (and no other fitting parameters), we propose a
simple theory that predicts the attractive chemical potential inferred from
experiments. As additional evidence for attractive forces, we present data for
salt adsorption in uncharged microporous carbons, also predicted by the theory.


title:
Invariant Differential Operators for Non-Compact Lie Groups: the Reduced
  SU(3,3) Multiplets

abstract:
  In the present paper we continue the project of systematic construction of
invariant differential operators on the example of the non-compact algebras
$su(n,n)$. Earlier were given the main multiplets of indecomposable elementary
representations for $n\leq 4$, and the reduced ones for $n=2$. Here we give all
reduced multiplets containing physically relevant representations including the
minimal ones for the algebra $su(3,3)$. Due to the recently established
parabolic relations the results are valid also for the algebra
$sl(6,\mathbb{R})$ with suitably chosen maximal parabolic subalgebra.


title: Heavy Probes in Strongly Coupled Plasmas With Chemical Potential

abstract:
  We study the properties of heavy probes moving in strongly coupled plasmas at
finite chemical potential. Using the gauge/gravity duality we consider large
classes of gravity models consisting in deformed AdS5 spacetimes endowed with
Reissner-Nordstr\"om-type black holes. We report on our analysis of the
screening distance of a quark-antiquark pair, its free energy, and the running
coupling. These observables show a certain insensitivity as to which model and
deformation is used, pointing to strong-coupling universal behavior. Thus, the
results may be relevant for modeling heavy quarkonia traversing a quark-gluon
plasma at finite net baryon density, and their suppression by melting.


title:
Lessons from a Large-Scale Assessment: Results from Conceptual
  Inventories

abstract:
  We report the conceptual inventory results of a large-scale assessment
project at a large university. We studied an attempt at introducing materials
and instructional methods informed by physics education research (PER-informed
materials) into a department where most instruction has been traditional and a
significant number of faculty are hesitant, ambivalent or even resistant about
the introduction of such reforms. The changes were made in the laboratories and
recitation sections of the introductory classes, both calculus-based and
algebra-based, introducing PER-informed materials and training the teaching
assistants in student-centered instructional methods. In addition to the
results found in the large lecture classes, we present the results of a small
PER-informed, inquiry-based, laboratory-based class that has been taught as a
special section of the algebra-based course for about 10 years. The assessment
reported in this paper was done using available PER-developed assessment
instruments. The results of other assessment instruments used in the project,
such as free-response pre- and post-tests, are reported in subsequent papers.
The results in this paper inform researchers in PER of the use of PER-informed
materials and instructional methods in a department not unified in the
introduction and implementation of these materials and the results of the
implementation as assessed by PER-based conceptual inventories. We found that
our conceptual inventory scores were lower than many results reported elsewhere
in the literature. However, we did see a statistically significant increase in
the conceptual inventory scores with the implementation of PER-informed
laboratories and the use of student-centered pedagogy in the labs and
recitations. The increase was much greater, if the lecture instructor also used
PER-informed materials.


title:
On the Descartes-Frenicle-Sorli and Dris Conjectures Regarding Odd
  Perfect Numbers

abstract:
  Dris conjectured in his masters thesis that the inequality $q^k < n$ always
holds, if $N = {q^k}{n^2}$ is an odd perfect number with special prime $q$. In
this note, we initially show that either of the two conditions $n < q^k$ or
$\sigma(q)/n < \sigma(n)/q$ holds. This is achieved by first proving that
$\sigma(q)/n \neq \sigma(n)/q^k$, where $\sigma(x)$ is the sum of the divisors
of $x$. Using this analysis, we further show that the condition $q < n < q^k$
holds in four out of a total of six cases. Finally, we prove that $n < q^k$,
and that this holds unconditionally. This finding disproves both the Dris
Conjecture and the Descartes-Frenicle-Sorli Conjecture that $k = 1$.


title:
Stochastic Gradient Estimate Variance in Contrastive Divergence and
  Persistent Contrastive Divergence

abstract:
  Contrastive Divergence (CD) and Persistent Contrastive Divergence (PCD) are
popular methods for training the weights of Restricted Boltzmann Machines.
However, both methods use an approximate method for sampling from the model
distribution. As a side effect, these approximations yield significantly
different biases and variances for stochastic gradient estimates of individual
data points. It is well known that CD yields a biased gradient estimate. In
this paper we however show empirically that CD has a lower stochastic gradient
estimate variance than exact sampling, while the mean of subsequent PCD
estimates has a higher variance than exact sampling. The results give one
explanation to the finding that CD can be used with smaller minibatches or
higher learning rates than PCD.


title: Herbert Stahl's proof of the BMV conjecture

abstract:
  The paper contains a simplified version of Stahl's proof of a conjecture of
Bessis, Moussa and Villani on the trace of matrices A+tB with Hermitean A and
B.


title: The Effect of Problem Format on Students Responses

abstract:
  As part of large-scale assessment project at Texas Tech University, we
studied the effect of problem format on students responses to quiz questions.
The same problem was written in multiple formats and administered as a quiz in
the large introductory physics sections in both the algebra-based and
calculus-based classes. The formats included multiple-choice (MC) only, MC and
free response (FR) and FR only. Variations in the FR wording were also
explored. We examined the ability of students to both choose the correct answer
and correctly explain their reasoning and show their calculations. We also
analyzed the type of written responses the students used to support their
answers. We found that a large percentage of the students who chose the correct
answer could not support their answer with correct reasoning or calculations.


title: Volume inequalities for the $i$-th-Convolution bodies

abstract:
  We obtain a new extension of Rogers-Shephard inequality providing an upper
bound for the volume of the sum of two convex bodies $K$ and $L$. We also give
lower bounds for the volume of the $k$-th limiting convolution body of two
convex bodies $K$ and $L$. Special attention is paid to the $(n-1)$-th limiting
convolution body, for which a sharp inequality, which is equality only when
$K=-L$ is a simplex, is given. Since the $n$-th limiting convolution body of
$K$ and $-K$ is the polar projection body of $K$, these inequalities can be
viewed as an extension of Zhang's inequality.


title:
Time-dependent Landauer-B\"uttiker formula: application to transient
  dynamics in graphene nanoribbons

abstract:
  In this work we develop a time-dependent extension of the Landauer-B\"uttiker
approach to study transient dynamics in time-dependent quantum transport
through molecular junctions. A key feature of the approach is that it provides
a closed integral expression for the time-dependence of the density matrix of
the molecular junction after switch-on of a bias or gate potential which can be
evaluated without the necessity of propagating individual single-particle
orbitals. This allows for the study of time-dependent transport in large
molecular systems coupled to wide band leads. As an application of the
formalism we study the transient dynamics of zigzag and armchair graphene
nanoribbons of different symmetries. We find that the transient times can
exceed several hundreds of femtoseconds while displaying a long time
oscillatory motion related to multiple reflections of the density wave in the
nanoribbons at the ribbon--lead interface. This temporal profile has a shape
that scales with the length of the ribbons and is modulated by fast
oscillations described by intra-ribbon and ribbon--lead transitions. Especially
in the armchair nanoribbons there exists a sequence of quasi-stationary states
related to reflections at the edge state located at the ribbon--lead interface.
In the case of zigzag nanoribbons there is a predominant oscillation frequency
associated with virtual transitions between the edge states and the Fermi
levels of the electrode. We further study the local bond currents in the
nanoribbons and find that the parity of the edges strongly affects the path of
the electrons in the nanoribbons. We finally study the behavior of the
transients for various added gate potentials.


title: A quantum information approach to statistical mechanics

abstract:
  We review some connections between quantum information and statistical
mechanics. We focus on three sets of results for classical spin models. First,
we show that the partition function of all classical spin models (including
models in different dimensions, different types of many-body interactions,
different symmetries, etc) can be mapped to the partition function of a single
model. Second, we give efficient quantum algorithms to estimate the partition
function of various classical spin models, such as the Ising or the Potts
model. The proofs of these two results are based on a mapping from partition
functions to quantum states and to quantum circuits, respectively. Finally, we
show how classical spin models can be used to describe certain fluctuating
lattices appearing in models of discrete quantum gravity.


title:
Rational points of varieties with ample cotangent bundle over function
  fields of positive characteristic

abstract:
  Let $K$ be the function field of a smooth curve over an algebraically closed
field $k$. Let $X$ be a scheme, which is smooth and projective over $K$.
Suppose that the cotangent bundle $\Omega_{X/K}$ is ample. Let $R:={\rm
Zar}(X)(K)\cap X)$ be the Zariski closure of the set of all $K$-rational points
of $X$, endowed with its reduced induced structure. We prove that there is a
projective variety $X_0$ over $k$ and a finite and surjective $K^{\rm
sep}$-morphism $X_{0,K^{\rm sep}}\to R_{K^{\rm sep}}$, which is birational when
${\rm char}(K)=0$.


title: Q-weak: First Direct Measurement of the Weak Charge of the Proton

abstract:
  The Q-weak experiment at Hall C of Thomas Jefferson National Accelerator
Facility has made the first direct measurement of the weak charge of the
proton, Qweak(p), through a precision measurement of the parity-violating
asymmetry in elastic e-p scattering at low momentum transfer Q^2= 0.025
(GeV/c)^2 with incident electron beam energy of 1.155 GeV. The Q-weak
experiment, along with earlier results of parity violating elastic scattering
experiments, is expected to determine the most precise value of Qweak(p) which
is suppressed in the Standard Model. If this result is further combined with
the 133Cs atomic parity violation (APV) measurement, significant constraints on
the weak charge of the up quark, down quark, and neutron can be extracted. This
data will also be used to determine the weak-mixing angle, sin^2 theta_?W, with
a relative uncertainty of < 0.5% that will provide a competitive measurement of
the running of sin^2 theta_?W to low Q^2. An overview of the experiment and its
results using the commissioning dataset, constituting approximately 4% of the
data collected in the experiment, are reported here.


title:
Photonic band-gap engineering for volume plasmon polaritons in
  multiscale multilayer hyperbolic metamaterials

abstract:
  We theoretically study the propagation of large-wavevector waves (volume
plasmon polaritons) in multilayer hyperbolic metamaterials with two levels of
structuring. We show that when the parameters of a subwavelength
metal-dielectric multilayer ("substructure") are modulated ("superstructured")
on a larger, wavelength scale, the propagation of volume plasmon polaritons in
the resulting multiscale hyperbolic metamaterials is subject to photonic band
gap phenomena. A great degree of control over such plasmons can be exerted by
varying the superstructure geometry. When this geometry is periodic, stop bands
due to Bragg reflection form within the volume plasmonic band. When a cavity
layer is introduced in an otherwise periodic superstructure, resonance peaks of
the Fabry-Perot nature are present within the stop bands. More complicated
superstructure geometries are also considered. For example, fractal Cantor-like
multiscale metamaterials are found to exhibit characteristic self-similar
spectral signatures in the volume plasmonic band. Multiscale hyperbolic
metamaterials are shown to be a promising platform for large-wavevector bulk
plasmonic waves, whether they are considered for use as a new kind of
information carrier or for far-field subwavelength imaging.


title: Atomic resolution STM in a cryogen free dilution refrigerator at 15 mK

abstract:
  Pulse tube refrigerators are becoming more common, because they are cost
efficient and demand less handling than conventional (wet) refrigerators.
However, a downside of a pulse tube system is the vibration level at the
cold-head, which is in most designs several micrometers. We implemented
vibration isolation techniques which significantly reduced vibration levels at
the experiment. These optimizations were necessary for the vibration sensitive
Magnetic Resonance Force Microscopy experiments (MRFM) at milli-kelvin
temperatures for which the cryostat is intended. With these modifications we
show atomic resolution STM on graphite. This is promising for scanning probe
microscopy applications at very low temperatures.


title:
Rates of mixing for the Weil-Petersson geodesic flow I: no rapid mixing
  in non-exceptional moduli spaces

abstract:
  We show that the rate of mixing of the Weil-Petersson flow on non-exceptional
(higher dimensional) moduli spaces of Riemann surfaces is at most polynomial.


title:
Reconstructing the sky location of gravitational-wave detected compact
  binary systems: methodology for testing and comparison

abstract:
  The problem of reconstructing the sky position of compact binary coalescences
detected via gravitational waves is a central one for future observations with
the ground-based network of gravitational-wave laser interferometers, such as
Advanced LIGO and Advanced Virgo. Different techniques for sky localisation
have been independently developed. They can be divided in two broad categories:
fully coherent Bayesian techniques, which are high-latency and aimed at
in-depth studies of all the parameters of a source, including sky position, and
"triangulation-based" techniques, which exploit the data products from the
search stage of the analysis to provide an almost real-time approximation of
the posterior probability density function of the sky location of a detection
candidate. These techniques have previously been applied to data collected
during the last science runs of gravitational-wave detectors operating in the
so-called initial configuration.
  Here, we develop and analyse methods for assessing the self-consistency of
parameter estimation methods and carrying out fair comparisons between
different algorithms, addressing issues of efficiency and optimality. These
methods are general, and can be applied to parameter estimation problems other
than sky localisation. We apply these methods to two existing sky localisation
techniques representing the two above-mentioned categories, using a set of
simulated inspiral-only signals from compact binary systems with total mass
$\le 20\,M_\odot$ and non-spinning components. We compare the relative
advantages and costs of the two techniques and show that sky location
uncertainties are on average a factor $\approx 20$ smaller for fully coherent
techniques than for the specific variant of the "triangulation-based" technique
used during the last science runs, at the expense of a factor $\approx 1000$
longer processing time.


title: Multiple phases in sputtered Cr2CoGa films

abstract:
  By magnetron co-sputtering, thin films of a nominal Cr2CoGa compound were
deposited on MgO and MgAl2O4. To achieve crystallisation in the inverse Heusler
structure, different heat treatments were tested. Instead of the inverse
Heusler structure, we observed phase separation and precipitate formation in
dependence on the heat treatment. The main precipitate is Cr3Ga in A15
structure. The remainder forms Co-rich CoGa in the B2 structure and possibly
Cr-rich CoCr in the sigma-phase.


title:
Qualitative Analysis of the Time-Frequency Signature Induced by a
  Reflected L-Band Signal from Time Evolving Sea Surfaces

abstract:
  Passive remote sensing techniques have become more and more popular for
detection and characterization purposes. The advantage of using the Global
Navigation Satellite Systems (GNSS) are the well known signals emitted and the
availability in most areas on Earth. In the present paper, L-Band signals
(including GNSS signals) are considered for oceanographic purposes. The main
interest in this contribution is the analysis of the signal reflected by an
evolving sea surface using time-frequency transforms. The features which occur
in this domain are examined in relation to the physical phenomena: interaction
of the electromagnetic waves with the moving sea surface.


title:
Cosmological simulations of screened modified gravity out of the static
  approximation: effects on matter distribution

abstract:
  In the context of scalar tensor theories for gravity, there is a universally
adopted hypothesis when running N-body simulations that time derivatives in the
equation of motion for the scalar field are negligible. In this work we propose
to test this assumption for one specific scalar-tensor model with a gravity
screening mechanism: the symmetron. To this end, we implemented the necessary
modifications to include the non-static terms in the N-body code Ramses. We
present test cases and results from cosmological simulations. Our main finding
when comparing static vs. non-static simulations is that the global power
spectrum is only slightly modified when taking into account the inclusion of
non-static terms. On the contrary, we find that the calculation of the local
power spectrum gives different measurements. Such results imply one must be
careful when assuming the quasi-static approximation when investigating the
environmental effects of modified gravity and screening mechanisms in structure
formation of halos and voids distributions.


title:
Spin-memory effect and negative magnetoresistance in hopping
  conductivity

abstract:
  We propose a mechanism for negative isotropic magnetoresistance in the
hopping regime. It results from a memory effect encrypted into spin
correlations that are not taken into account by the conventional theory of
hopping conductivity. The spin correlations are generated by the nonequilibrium
electric currents and lead to the decrease of the conductivity. The application
of the magnetic field destroys the correlations thus enhancing the conductance.
This effect can occur even at magnetic fields as small as a few gauss.


title: Quantum Reflection of Antihydrogen in the GBAR Experiment

abstract:
  In the GBAR experiment, cold antihydrogen atoms will be left to fall on an
annihilation plate with the aim of measuring the gravitational acceleration of
antimatter. Here, we study the quantum reflection of these antiatoms due to the
Casimir-Polder potential above the plate. We give realistic estimates of the
potential and quantum reflection amplitudes, taking into account the
specificities of antihydrogen and the optical properties of the plate. We find
that quantum reflection is enhanced for weaker potentials, for example above
thin slabs, graphene and nanoporous media.


title:
Fractional Klein-Gordon equation for linear dispersive phenomena:
  analytical methods and applications

abstract:
  In this paper we discuss some exact results related to the fractional
Klein--Gordon equation involving fractional powers of the D'Alembert operator.
By means of a space-time transformation, we reduce the fractional Klein--Gordon
equation to a fractional hyper-Bessel-type equation. We find an exact analytic
solution by using the McBride theory of fractional powers of hyper-Bessel
operators. A discussion of these results within the framework of linear
dispersive wave equations is provided. We also present exact solutions of the
fractional Klein-Gordon equation in the higher dimensional cases. Finally, we
suggest a method of finding travelling wave solutions of the nonlinear
fractional Klein-Gordon equation with power law nonlinearities.


title:
Non-resonant excitation of a two-level atom driven by a superoscillating
  field

abstract:
  We study counterintuitive dynamics of a two-level system (TLS) interacting
with electric field superoscillating in time. We show that a TLS may be excited
by an external light pulse whose spectral components are below the absorption
line of the TLS. We attribute this unique dynamics to the Rabi oscillations of
the TLS in a superoscillating driving field.


title: CDF Run II Silicon Vertex Detector Annealing Study

abstract:
  Between Run II commissioning in early 2001 and the end of operations in
September 2011, the Tevatron collider delivered 12~fb$^{-1}$ of $p\bar{p}$
collisions at $\sqrt{s}=1.96$ TeV to the Collider Detector at Fermilab (CDF).
During that time, the CDF silicon vertex detector was subject to radiation
doses of up to 12 Mrad. After the end of operations, the silicon detector was
annealed for 24 days at $18^{\circ}$C. In this paper, we present a measurement
of the change in the bias currents for a subset of sensors during the annealing
period. We also introduce a novel method for monitoring the depletion voltage
throughout the annealing period. The observed bias current evolution can be
characterized by a falling exponential term with time constant
$\tau_I=17.88\pm0.36$(stat.)$\pm0.25$(syst.) days. We observe an average
decrease of $(27\pm3)\%$ in the depletion voltage, whose evolution can
similarly be described by an exponential time constant of $\tau_V=6.21\pm0.21$
days. These results are consistent with the Hamburg model within the
measurement uncertainties.


title:
Quantum Jarzynski equalities for the energy costs of the information
  processes

abstract:
  We present quantum versions of the Jarzynski equality for the energy costs of
information processes, namely the measurement and the information erasure. We
also obtain inequalities for the energy costs of the information processes,
using the Jensen inequality. The inequalities include Sagawa and Ueda's
inequalities [Phys. Rev. Lett. 102, 250602 (2009)] as a special case.


title: More elementary operators that are spectrally bounded

abstract:
  We discuss some necessary and some sufficient conditions for an elementary
operator $x\mapsto\sum_{i=1}^n a_ixb_i$ on a Banach algebra $A$ to be
spectrally bounded. In the case of length three, we obtain a complete
characterisation when $A$ acts irreducibly on a Banach space of dimension
greater than three.


title: Occupancy Detection in Vehicles Using Fisher Vector Image Representation

abstract:
  Due to the high volume of traffic on modern roadways, transportation agencies
have proposed High Occupancy Vehicle (HOV) lanes and High Occupancy Tolling
(HOT) lanes to promote car pooling. However, enforcement of the rules of these
lanes is currently performed by roadside enforcement officers using visual
observation. Manual roadside enforcement is known to be inefficient, costly,
potentially dangerous, and ultimately ineffective. Violation rates up to
50%-80% have been reported, while manual enforcement rates of less than 10% are
typical. Therefore, there is a need for automated vehicle occupancy detection
to support HOV/HOT lane enforcement. A key component of determining vehicle
occupancy is to determine whether or not the vehicle's front passenger seat is
occupied. In this paper, we examine two methods of determining vehicle front
seat occupancy using a near infrared (NIR) camera system pointed at the
vehicle's front windshield. The first method examines a state-of-the-art
deformable part model (DPM) based face detection system that is robust to
facial pose. The second method examines state-of- the-art local aggregation
based image classification using bag-of-visual-words (BOW) and Fisher vectors
(FV). A dataset of 3000 images was collected on a public roadway and is used to
perform the comparison. From these experiments it is clear that the image
classification approach is superior for this problem.


title:
Ultrafast modulation of the chemical potential in BaFe$_2$As$_2$ by
  coherent phonons

abstract:
  Time- and angle-resolved extreme ultraviolet photoemission spectroscopy is
used to study the electronic structure dynamics in BaFe$_2$As$_2$ around the
high-symmetry points $\Gamma$ and $M$. A global oscillation of the Fermi level
at the frequency of the $A_{1g}$(As) phonon mode is observed. It is argued that
this behavior reflects a modulation of the effective chemical potential in the
photoexcited surface region that arises from the high sensitivity of the band
structure near the Fermi level to the $A_{1g}$ phonon mode combined with a low
electron diffusivity perpendicular to the layers. The results establish a novel
way to tune the electronic properties of iron pnictides: coherent control of
the effective chemical potential. The results further suggest that the
equilibration time for the effective chemical potential needs to be considered
in the ultrafast electronic structure dynamics of materials with weak
interlayer coupling.


title: How to Construct Deep Recurrent Neural Networks

abstract:
  In this paper, we explore different ways to extend a recurrent neural network
(RNN) to a \textit{deep} RNN. We start by arguing that the concept of depth in
an RNN is not as clear as it is in feedforward neural networks. By carefully
analyzing and understanding the architecture of an RNN, however, we find three
points of an RNN which may be made deeper; (1) input-to-hidden function, (2)
hidden-to-hidden transition and (3) hidden-to-output function. Based on this
observation, we propose two novel architectures of a deep RNN which are
orthogonal to an earlier attempt of stacking multiple recurrent layers to build
a deep RNN (Schmidhuber, 1992; El Hihi and Bengio, 1996). We provide an
alternative interpretation of these deep RNNs using a novel framework based on
neural operators. The proposed deep RNNs are empirically evaluated on the tasks
of polyphonic music prediction and language modeling. The experimental result
supports our claim that the proposed deep RNNs benefit from the depth and
outperform the conventional, shallow RNNs.


title: Universal properties of group actions on locally compact spaces

abstract:
  We study universal properties of locally compact G-spaces for countable
infinite groups G. In particular we consider open invariant subsets of the
\beta-compactification of G (which is a G-space in a natural way), and their
minimal closed invariant subspaces. These are locally compact free G-spaces,
and the latter are also minimal. We examine the properies of these G-spaces
with emphasis on their universal properties.
  As an example of our resuts, we use combinatorial methods to show that each
countable infinite group admits a free minimal action on the locally compact
non-compact Cantor set.


title:
The Kardar-Parisi-Zhang equation with spatially correlated noise: a
  unified picture from nonperturbative renormalization group

abstract:
  We investigate the scaling regimes of the Kardar-Parisi-Zhang equation in the
presence of spatially correlated noise with power law decay $D(p) \sim
p^{-2\rho}$ in Fourier space, using a nonperturbative renormalization group
approach. We determine the full phase diagram of the system as a function of
$\rho$ and the dimension $d$. In addition to the weak-coupling part of the
diagram, which agrees with the results from Refs. [Europhys. Lett. 47, 14
(1999), Eur. Phys. J. B 9, 491 (1999)], we find the two fixed points describing
the short-range (SR) and long-range (LR) dominated strong-coupling phases. In
contrast with a suggestion in the references cited above, we show that, for all
values of $\rho$, there exists a unique strong-coupling SR fixed point that can
be continuously followed as a function of $d$. We show in particular that the
existence and the behavior of the LR fixed point do not provide any hint for 4
being the upper critical dimension of the KPZ equation with SR noise.


title: Ageing of the 2+1 dimensional Kardar-Parisi-Zhang model

abstract:
  Extended dynamical simulations have been performed on a 2+1 dimensional
driven dimer lattice gas model to estimate ageing properties. The
auto-correlation and the auto-response functions are determined and the
corresponding scaling exponents are tabulated. Since this model can be mapped
onto the 2+1 dimensional Kardar-Parisi-Zhang surface growth model, our results
contribute to the understanding of the universality class of that basic system.

categories: cond-mat.stat-mech cond-mat.mtrl-sci cs.DC nlin.CG physics.comp-ph


title:
Refined approximations for the distortion visibility function and
  mu-type spectral distortions

abstract:
  The physical processes affecting the thermalization of cosmic microwave
background spectral distortions are very simple and well understood. This
allows us to make precise predictions for the distortions signals caused by
various energy release scenarios, where the theoretical uncertainty is largely
dominated by the physical ingredients that are used for the calculation. Here,
we revisit various approximations for the distortion visibility function --
defined using the fraction of the released energy that does not thermalize --
and early $\mu$-type distortions. Our approach is based on a perturbative
expansion, which allows us to identify and clarify the origin of different
improvements over earlier approximations. It provides a better than ~0.1%-1%
description of our numerical results over a wide range of parameters. In
particular, we are able to capture the high-frequency part of the
mu-distortion, which directly depends on the time derivative of the electron
temperature. We also include lowest order double Compton and Compton scattering
relativistic corrections, finding that because of cancelation they increase the
thermalization efficiency in the tail of the distortion visibility function by
only ~10% (at $z\lesssim 6\times10^6$), although individually their effect can
reach ~20%-40%.


title:
Gevrey Smoothing Effect for Solutions of the Non-Cutoff Boltzmann
  Equation in Maxwellian Molecules Case

abstract:
  In this paper we study the Gevrey regularity for the weak solutions to the
Cauchy problem of the non-cutoff spatially homogeneous Botlzmann equation for
the Maxwellian molecules model with the singularity exponent $s\in (0,1)$. We
establish that any weak solution belongs to the Gevrey spaces for any positive
time.


title: Information and optimal investment in defaultable assets

abstract:
  We study optimal investment in an asset subject to risk of default for
investors that rely on different levels of information. The price dynamics can
include noises both from a Wiener process and a Poisson random measure with
infinite activity. The default events are modelled via a counting process in
line with large part of the literature in credit risk. In order to deal with
both cases of inside and partial information we consider the framework of the
anticipating calculus of forward integration. This does not require a priori
assumptions typical of the framework of enlargement of filtrations. We find
necessary and sufficient conditions for the existence of a locally maximizing
portfolio of the expected utility at terminal time. We consider a large class
of utility functions. In addition we show that the existence of the solution
implies the semi-martingale property of the noises driving the stock. Some
discussion on unicity of the maxima is included.


title: Coupling methods for random topological Markov chains

abstract:
  We apply coupling techniques in order to prove that the transfer operators
associated with random topological Markov chains and non-stationary shift
spaces with the big images and preimages-property have a spectral gap.


title:
Deep Inside Convolutional Networks: Visualising Image Classification
  Models and Saliency Maps

abstract:
  This paper addresses the visualisation of image classification models, learnt
using deep Convolutional Networks (ConvNets). We consider two visualisation
techniques, based on computing the gradient of the class score with respect to
the input image. The first one generates an image, which maximises the class
score [Erhan et al., 2009], thus visualising the notion of the class, captured
by a ConvNet. The second technique computes a class saliency map, specific to a
given image and class. We show that such maps can be employed for weakly
supervised object segmentation using classification ConvNets. Finally, we
establish the connection between the gradient-based ConvNet visualisation
methods and deconvolutional networks [Zeiler et al., 2013].


title:
Local and Global Well-posedness of Strong Solutions to the 3D Primitive
  Equations with Vertical Eddy Diffusivity

abstract:
  In this paper, we consider the initial-boundary value problem of the viscous
3D primitive equations for oceanic and atmospheric dynamics with only vertical
diffusion in the temperature equation. Local and global well-posedness of
strong solutions are established for this system with $H^2$ initial data.

categories: math.AP physics.ao-ph physics.flu-dyn physics.geo-ph


title:
Crowdsourced bi-directional disaster reporting and alerting on
  smartphones in Lao PDR

abstract:
  Natural disasters are a large threat for people especially in developing
countries such as Laos. ICT-based disaster management systems aim at supporting
disaster warning and response efforts. However, the ability to directly
communicate in both directions between local and administrative level is often
not supported, and a tight integration into administrative workflows is
missing. In this paper, we present the smartphone-based disaster and reporting
system Mobile4D. It allows for bi-directional communication while being fully
involved in administrative processes. We present the system setup and discuss
integration into administrative structures in Lao PDR.


title:
Static and dynamical properties of a hard-disk fluid confined to a
  narrow channel

abstract:
  The thermodynamic properties of disks moving in a channel sufficiently narrow
that they can collide only with their nearest neighbors can be solved exactly
by determining the eigenvalues and eigenfunctions of an integral equation.
Using it we have determined the correlation length $\xi$ of this system. We
have developed an approximate solution which becomes exact in the high density
limit. It describes the system in terms of defects in the regular zigzag
arrangement of disks found in the high-density limit. The correlation length is
then effectively the spacing between the defects. The time scales for defect
creation and annihilation are determined with the help of transition-state
theory, as is the diffusion coefficient of the defects, and these results are
found to be in good agreement with molecular dynamics simulations. On
compressing the system with the Lubachevsky--Stillinger procedure, jammed
states are obtained whose packing fractions $\phi_J$ are a function of the
compression rate $\gamma$. We find a quantitative explanation of this
dependence by making use of the Kibble--Zurek hypothesis. We have also
determined the point-to-set length scale $\xi_{PS}$ for this system. At a
packing fraction $\phi$ close to its largest value $\phi_{\text{max}}$,
$\xi_{PS}$ has a simple power law divergence, $\xi_{PS} \sim
1/(1-\phi/\phi_{\text{max}})$, while $\xi$ diverges much faster, $\ln(\xi) \sim
1/(1-\phi/\phi_{\text{max}})$.


title: Hall Viscosity of Hierarchical Quantum Hall States

abstract:
  Using methods based on conformal field theory, we construct model wave
functions on a torus with arbitrary flat metric for all chiral states in the
abelian quantum Hall hierarchy. These functions have no variational parameters,
and they transform under the modular group in the same way as the
multicomponent generalizations of the Laughlin wave functions. Assuming the
absence of Berry phases upon adiabatic variations of the modular parameter
$\tau$, we calculate the quantum Hall viscosity and find it to be in agreement
with the formula, given by Read, which relates the viscosity to the average
orbital spin of the electrons. For the filling factor $\nu=2/5$ Jain state,
which is at the second level in the hierarchy, we compare our model wave
function with the numerically obtained ground state of the Coulomb interaction
Hamiltonian in the lowest Landau level, and find very good agreement in a large
region of the complex $\tau$-plane. For the same example, we also numerically
compute the Hall viscosity and find good agreement with the analytical result
for both the model wave function and the numerically obtained Coulomb wave
function. We argue that this supports the notion of a generalized plasma
analogy that would ensure that wave functions obtained using the conformal
field theory methods do not acquire Berry phases upon adiabatic evolution.


title: Succinct representation of labeled trees

abstract:
  We give a representation for labeled ordered trees that supports labeled
queries such as finding the i-th ancestor of a node with a given label. Our
representation is succinct, namely the redundancy is small-o of the optimal
space for storing the tree. This improves the representation of He et al. which
is succinct unless the entropy of the labels is small.


title: Newtonian Atlas for Dust-Filled FRW Universe

abstract:
  The metric of an FRW universe filled with pressureless dust is shown to
agree, close to any spacetime point, with a curved Newtonian-type metric where
Einstein's equations simplify to those of Newtonian gravity. The agreement is
shown to quadratic order in the local coordinates, so the curvatures agree.
This result is established by expressing both metrics in Riemann normal form.
This approach gives a local Newtonian understanding of cosmology that avoids
the paradoxes of global Newtonian cosmology.


title:
Computation of the Mean First-Encounter Time Between the Ends of a
  Polymer Chain

abstract:
  Using a novel theoretical approach, we study the mean first encounter time
(MFET) between the two ends of a polymer. Previous approaches used various
simplifications that reduced the complexity of the problem, leading, however to
incompatible results. We construct here for the first time a general theory
that allows us to compute the MFET. The method is based on estimating the mean
time for a Brownian particle to reach a narrow domain in the polymer
configuration space. In dimension two and three, we find that the MFET depends
mainly on the first eigenvalue of the associated Fokker-Planck operator and
provide precise estimates that are confirmed by Brownian simulations.
Interestingly, although many time scales are involved in the encounter process,
its distribution can be well approximated by a single exponential, which has
several consequences for modeling chromosome dynamics in the nucleus. Another
application of our result is computing the mean time for a DNA molecule to form
a closed loop (when its two ends meet for the first time).


title: Learning States Representations in POMDP

abstract:
  We propose to deal with sequential processes where only partial observations
are available by learning a latent representation space on which policies may
be accurately learned.


title: Thought Experiments on Gravitational Forces

abstract:
  Large contributions to the near closure of the Universe and to the
acceleration of its expansion are due to the gravitation of components of the
stress-energy tensor other than its mass density. To familiarise astronomers
with the gravitation of these components we conduct thought experiments on
gravity, analogous to the real experiments that our forebears conducted on
electricity. By analogy to the forces due to electric currents we investigate
the gravitational forces due to the flows of momentum, angular momentum, and
energy along a cylinder. Under tension the gravity of the cylinder decreases
but the 'closure' of the 3-space around it increases. When the cylinder carries
a torque the flow of angular momentum along it leads to a novel helical
interpretation of Levi-Civita's external metric and a novel relativistic
effect. Energy currents give gravomagnetic effects in which parallel currents
repel and antiparallel currents attract, though such effects must be added to
those of static gravity. The gravity of beams of light give striking
illustrations of these effects and a re-derivation of light bending via the
gravity of the light itself. Faraday's experiments lead us to discuss lines of
force of both gravomagnetic and gravity fields. A serious conundrum arrises if
Landau and Lifshitz's definition of Gravitational force is adopted.


title:
Matrix product state formulation of frequency-space dynamics at finite
  temperatures

abstract:
  We present a flexible density-matrix renormalization group approach to
calculate finite-temperature spectral functions of one-dimensional strongly
correlated quantum systems. The method combines the purification of the
finite-temperature density operator with a moment expansion of the Green's
function. Using this approach, we study finite-temperature properties of
dynamical spectral functions of spin-1/2 XXZ chains with Dzyaloshinskii-Moriya
interactions in magnetic fields and analyze the effect of these symmetry
breaking interactions on the nature of the finite-temperature dynamic spin
structure factor.


title: Asymptotic behavior for a class of non autonomous non local problems

abstract:
  In this paper we consider the non local non autonomous evolution problem \[
\begin{cases} \partial_t u =- u + g \left(\beta(t)(Ku) \right)\ \ \mbox{in}\ \
\Omega,\\ u = 0\ \ \mbox{in}\ \ \mathbb{R}^N\backslash\Omega, \end{cases} \]
where $\Omega$ is a smooth bounded domain in $\mathbb{R}^N$, $\beta$ denotes
the functional parameter given by a continuous bounded function on
$\mathbb{R}$, and $K$ is an integral operator with symmetric kernel. We prove
existence and some regularity properties of the pullback attractor.


title:
Top-level Design and Pilot Analysis of Low-end CT Scanners Based on
  Linear Scanning for Developing Countries

abstract:
  Purpose: The goal is to develop a new architecture for computed tomography
(CT) which is at an ultra-low-dose for developing countries, especially in
rural areas. Methods: The proposed scheme is inspired by the recently developed
compressive sensing and interior tomography techniques, where the data
acquisition system targets a region of interest (ROI) to acquire limited and
truncated data. The source and detector are translated in opposite directions
for either ROI reconstruction with one or more localized linear scans or global
reconstruction by combining multiple ROI reconstructions. In other words, the
popular slip ring is replaced by a translation based setup, and the
instrumentation cost is reduced by a relaxation of the imaging speed
requirement. Results: The various translational scanning modes are
theoretically analyzed, and the scanning parameters are optimized. The
numerical simulation results from different numbers of linear scans confirm the
feasibility of the proposed scheme, and suggest two preferred low-end systems
for horizontal and vertical patient positions respectively. Conclusion:
Ultra-low-cost x-ray CT is feasible with our proposed combination of linear
scanning, compressive sensing, and interior tomography. The proposed
architecture can be tailored into permanent, movable, or reconfigurable systems
as desirable. Advanced image registration and spectral imaging features can be
included as well.


title:
Mixed Finite Element Analysis of Lognormal Diffusion and Multilevel
  Monte Carlo Methods

abstract:
  This work is motivated by the need to develop efficient tools for uncertainty
quantification in subsurface flows associated with radioactive waste disposal
studies. We consider single phase flow problems in random porous media
described by correlated lognormal distributions. We are interested in the error
introduced by a finite element discretisation of these problems. In contrast to
several recent works on the analysis of standard nodal finite element
discretisations, we consider here mass-conservative lowest order Raviart-Thomas
mixed finite elements. This is very important since local mass conservation is
highly desirable in realistic groundwater flow problems. Due to the limited
spatial regularity and the lack of uniform ellipticity and boundedness of the
operator the analysis is non-trivial in the presence of lognormal random
fields. We establish finite element error bounds for Darcy velocity and
pressure, as well as for a more accurate recovered pressure approximation. We
then apply the error bounds to prove convergence of the multilevel Monte Carlo
algorithm for estimating statistics of these quantities. Moreover, we prove
convergence for a class of bounded, linear functionals of the Darcy velocity.
An important special case is the approximation of the effective permeability in
a 2D flow cell. We perform numerical experiments to confirm the convergence
results.


title: Minimum ranks of sign patterns via sign vectors and duality

abstract:
  A {\it sign pattern matrix} is a matrix whose entries are from the set
$\{+,-, 0\}$. The minimum rank of a sign pattern matrix $A$ is the minimum of
the ranks of the real matrices whose entries have signs equal to the
corresponding entries of $A$. It is shown in this paper that for any $m \times
n$ sign pattern $A$ with minimum rank $n-2$, rational realization of the
minimum rank is possible. This is done using a new approach involving sign
vectors and duality. It is shown that for each integer $n\geq 9$, there exists
a nonnegative integer $m$ such that there exists an $n\times m$ sign pattern
matrix with minimum rank $n-3$ for which rational realization is not possible.
A characterization of $m\times n$ sign patterns $A$ with minimum rank $n-1$ is
given (which solves an open problem in Brualdi et al. \cite{Bru10}), along with
a more general description of sign patterns with minimum rank $r$, in terms of
sign vectors of certain subspaces. A number of results on the maximum and
minimum numbers of sign vectors of $k$-dimensional subspaces of $\mathbb R^n$
are obtained. In particular, it is shown that the maximum number of sign
vectors of $2$-dimensional subspaces of $\mathbb R^n$ is $4n+1$. Several
related open problems are stated along the way.


title: A geometric introduction to the 2-loop renormalization group flow

abstract:
  The Ricci flow has been of fundamental importance in mathematics, most
famously though its use as a tool for proving the Poincar\'e Conjecture and
Thurston's Geometrization Conjecture. It has a parallel life in physics,
arising as the first order approximation of the Renormalization Group flow for
the nonlinear sigma model of quantum field theory. There recently has been
interest in the second order approximation of this flow, called the RG-2 flow,
which mathematically appears as a natural nonlinear deformation of the Ricci
flow. A curvature flow arising from quantum field theory seems to us to capture
the spirit of Yvonne Choquet Bruhat's extensive work in mathematical physics,
and so in this commemorative article we give a geometric introduction to the
RG-2 flow.
  A number of new results are presented as part of this narrative: short-time
existence and uniqueness results in all dimensions if the sectional curvatures
$K_{ij}$ satisfy certain inequalities; the calculation of fixed points for $n =
3$ dimensions; a reformulation of constant curvature solutions in terms of the
Lambert W function; a classification of the solutions that evolve only by
homothety; an analog for RG-flow of the 2-dimensional Ricci flow solution known
to mathematicians as the cigar soliton, and discussed in the physics literature
as Witten's black hole. We conclude with a list of Open Problems whose
resolutions would substantially increase our understanding of the RG-2 flow
both physically and mathematically.


title: Norming Sets and Related Remez-type Inequalities

abstract:
  The classical Remez inequality bounds the maximum of the absolute value of a
real polynomial $P$ of degree $d$ on $[-1,1]$ through the maximum of its
absolute value on any subset $Z\subset [-1,1]$ of positive Lebesgue measure.
Extensions to several variables and to certain sets of Lebesgue measure zero,
massive in a much weaker sense, are available.
  Still, given a subset $Z\subset [-1,1]^n\subset {\mathbb R}^n$ it is not easy
to determine whether it is ${\mathcal P}_d({\mathbb R}^n)$-norming (here
${\mathcal P}_d({\mathbb R}^n)$ is the space of real polynomials of degree at
most $d$ on ${\mathbb R}^n$), i.e. satisfies a Remez-type inequality:
$\sup_{[-1,1]^n}|P|\le C\sup_{Z}|P|$ for all $P\in {\mathcal P}_d({\mathbb
R}^n)$ with $C$ independent of $P$. (Although ${\mathcal P}_d({\mathbb
R}^n)$-norming sets are exactly those not contained in any algebraic
hypersurface of degree $d$ in ${\mathbb R}^n$, there are many apparently
unrelated reasons for $Z \subset [-1,1]^n$ to have this property.)
  In the present paper we study norming sets and related Remez-type
inequalities in a general setting of finite-dimensional linear spaces $V$ of
continuous functions on $[-1,1]^n$, remaining in most of the examples in the
classical framework. First, we discuss some sufficient conditions for $Z$ to be
$V$-norming, partly known, partly new, restricting ourselves to the simplest
non-trivial examples. Next, we extend the Turan-Nazarov inequality for
exponential polynomials to several variables, and on this base prove a new
fewnomial Remez-type inequality. Finally, we study the family of optimal
constants $N_{V}(Z)$ in the Remez-type inequalities for $V$, as the function of
the set $Z$, showing that it is Lipschitz in the Hausdorff metric.


title:
Isovector dipole-resonance structure within the effective surface
  approximation

abstract:
  The nuclear isovector-dipole strength structure is analyzed in terms of the
main and satellite (pygmy) peaks within the Fermi-liquid droplet model. Such a
structure is sensitive to the value of the surface symmetry-energy constant
obtained analytically for different Skyrme forces in the leptodermous effective
surface approximation. Energies, sum rules and transition densities of the main
and satellite peaks for specific Skyrme forces are qualitatively in agreement
with the experimental data and other theoretical calculations.


title: Subliminal Probing for Private Information via EEG-Based BCI Devices

abstract:
  Martinovic et al. proposed a Brain-Computer-Interface (BCI) -based attack in
which an adversary is able to infer private information about a user, such as
their bank or area-of-living, by analyzing the user's brain activities.
However, a key limitation of the above attack is that it is intrusive,
requiring user cooperation, and is thus easily detectable and can be reported
to other users. In this paper, we identify and analyze a more serious threat
for users of BCI devices. We propose a it subliminal attack in which the victim
is attacked at the levels below his cognitive perception. Our attack involves
exposing the victim to visual stimuli for a duration of 13.3 milliseconds -- a
duration usually not sufficient for conscious perception. The attacker analyzes
subliminal brain activity in response to these short visual stimuli to infer
private information about the user. If carried out carefully, for example by
hiding the visual stimuli within screen content that the user expects to see,
the attack may remain undetected. As a consequence, the attacker can scale it
to many victims and expose them to the attack for a long time. We
experimentally demonstrate the feasibility of our subliminal attack via a
proof-of-concept study carried out with 27 subjects. We conducted experiments
on users wearing Electroencephalography-based BCI devices, and used portrait
pictures of people as visual stimuli which were embedded within the background
of an innocuous video for a time duration not exceeding 13.3 milliseconds. Our
experimental results show that it is feasible for an attacker to learn relevant
private information about the user, such as whether the user knows the identity
of the person for which the attacker is probing.


title: Semi-Bloch functions in several complex variables

abstract:
  Let $M$ be an $n$-dimensional complex manifold. A holomorphic function
$f:M\to \mathbb C$ is said to be semi-Bloch if for every $\lambda\in \mathbb C$
the function $g_\lambda=\exp(\lambda f(z))$ is normal on $M$. We characterise
Semi-Bloch functions on infinitesimally Kobayashi non-degenerate $M$ in
geometric as well as analytic terms. Moreover, we show that on such manifolds,
semi-Bloch functions are normal.


title: Stability and magnetism in complex multivacancy graphene systems

abstract:
  This work is focused in the stability and magnetic properties of complex
graphene multivacancy systems, studied by Density Functional Theory
calculations. The removal of a sequence of carbon atoms -i.e. the complementary
figure- leads to these multivacancy systems. We show evidence that
dendritic-like complementary figures yield to very stable defected graphene
structures. If this dendritic complementary figure is aliphatic, the stress of
the defected graphene system is enough to decrease the symmetry of such a
system. In the cases that the complementary figure is based in phenyl- or
pyrenyl-like cores, the remaining system with the vacancy will preserve the
symmetry of the removed segment yielding to flower-like structures after
optimization. This has consequences in the magnetic arrangement based on the
dangling bonds located at the loose vertices of the pentagonal rings. The cases
with orthogonal anisotropy, the magnetic order is driven by the symmetry of the
vacancy system -i.e. the symmetry of the complementary figure-.


title: Unit Tests for Stochastic Optimization

abstract:
  Optimization by stochastic gradient descent is an important component of many
large-scale machine learning algorithms. A wide variety of such optimization
algorithms have been devised; however, it is unclear whether these algorithms
are robust and widely applicable across many different optimization landscapes.
In this paper we develop a collection of unit tests for stochastic
optimization. Each unit test rapidly evaluates an optimization algorithm on a
small-scale, isolated, and well-understood difficulty, rather than in
real-world scenarios where many such issues are entangled. Passing these unit
tests is not sufficient, but absolutely necessary for any algorithms with
claims to generality or robustness. We give initial quantitative and
qualitative results on numerous established algorithms. The testing framework
is open-source, extensible, and easy to apply to new algorithms.


title:
Formation and post-formation dynamics of bacterial biofilm streamers as
  highly viscous liquid jets

abstract:
  It has been recently reported that in presence of low Reynolds number (Re<<1)
transport, preformed bacterial biofilms, several hours after their formation,
may degenerate in form of filamentous structures, known as streamers. In this
letter, we explain that such streamers form as the highly viscous liquid states
of the intrinsically viscoelastic biofilms. Such "viscous liquid" state can be
hypothesized by noting that the time of appearance of the streamers is
substantially larger than the viscoelastic relaxation time scale of the
biofilms, and this appearance is explained by the inability of a viscous liquid
to withstand an external shear. Further, by identifying the post formation
dynamics of the streamers as that of a viscous liquid jet in a surrounding flow
field, we can interpret several unexplained issues associated with the
post-formation dynamics of streamers, such as the clogging of the flow passage
or the exponential time growth of streamer dimensions.


title:
On the Joint Impact of Beamwidth and Orientation Error on Throughput in
  Directional Wireless Poisson Networks

abstract:
  We introduce a model for capturing the effects of beam misdirection on
coverage and throughput in a directional wireless network using stochastic
geometry. In networks employing ideal sector antennas without sidelobes, we
find that concavity of the orientation error distribution is sufficient to
prove monotonicity and quasi-concavity (both with respect to antenna beamwidth)
of spatial throughput and transmission capacity, respectively. Additionally, we
identify network conditions that produce opposite extremal choices in beamwidth
(absolutely directed versus omni-directional) that maximize the two related
throughput metrics. We conclude our paper with a numerical exploration of the
relationship between mean orientation error, throughput-maximizing beamwidths,
and maximum throughput, across radiation patterns of varied complexity.


title:
Comparison of particle trajectories and collision operators for
  collisional transport in nonaxisymmetric plasmas

abstract:
  In this work, we examine the validity of several common simplifying
assumptions used in numerical neoclassical calculations for nonaxisymmetric
plasmas, both by using a new continuum drift-kinetic code and by considering
analytic properties of the kinetic equation. First, neoclassical phenomena are
computed for the LHD and W7-X stellarators using several versions of the
drift-kinetic equation, including the commonly used incompressible-ExB-drift
approximation and two other variants, corresponding to different effective
particle trajectories. It is found that for electric fields below roughly one
third of the resonant value, the different formulations give nearly identical
results, demonstrating the incompressible ExB-drift approximation is quite
accurate in this regime. However, near the electric field resonance, the models
yield substantially different results. We also compare results for various
collision operators, including the full linearized Fokker-Planck operator. At
low collisionality, the radial transport driven by radial gradients is nearly
identical for the different operators, while in other cases it is found to be
important that collisions conserve momentum.


title:
Implementation of a local principal curves algorithm for neutrino
  interaction reconstruction in a liquid argon volume

abstract:
  A local principal curve algorithm has been implemented in three dimensions
for automated track and shower reconstruction of neutrino interactions in a
liquid argon time projection chamber. We present details of the algorithm and
characterise its performance on simulated data sets.