title: Observations of Binary Systems with the H.E.S.S. Telescopes

abstract:
  Observations of binary systems obtained recently with the High Energy
Stereoscopic System (H.E.S.S) of Cherenkov telescopes are reported. The
outcomes of a detailed observation campaign on PSR B1259-63 during its
periastron passage in 2014 will be presented. This system was observed for the
first time with H.E.S.S. II, providing spectra and light curves down to 200
GeV, which will be compared with observations conducted during previous
periastron passages and with results from an analysis of contemporaneously
taken Fermi-LAT data. Also long-term observations of LS 5039 with H.E.S.S in
phase I and phase II are reported. This source was monitored at very high
energies (VHEs) in a period of time spanning more than ten years. Its spectral
energy distribution measured with H.E.S.S. II extends down to 120 GeV. Spectral
results from the Fermi-LAT observations are shown as well, and the
compatibility with H.E.S.S. results in the overlapping energy range is
discussed. The identification of the new gamma-ray binary candidate HESS
J1832-093 will also be presented. Furthermore, the search for VHE emission from
the microquasars GRS 1915+105, Circinus X-1 and V4641 Sgr based on data from
H.E.S.S. observations conducted contemporaneously with the RXTE satellite
experiment will be reported. These data provide constraints on the integral
gamma-ray flux at different X-ray states of the three sources.


title:
Lower bounds on the size of general Schr\"odinger-cat states from
  experimental data

abstract:
  Experimental progress with meso- and macroscopic quantum states (i.e.,
general Schrodinger-cat states) was recently accompanied by theoretical
proposals on how to measure the merit of these efforts. So far, experiment and
theory were disconnected as theoretical analysis of actual experimental data
was missing. Here, we consider a proposal for macroscopic quantum states that
measures the extend of quantum coherence present in the system. For this, the
quantum Fisher information is used. We calculate lower bounds from real
experimental data. The results are expressed as an "effective size", that is,
relative to "classical" reference states. We find remarkable numbers of up to
70 in photonic and atomic systems.


title: On the Optimality of Tape Merge of Two Lists with Similar Size

abstract:
  The problem of merging sorted lists in the least number of pairwise
comparisons has been solved completely only for a few special cases. Graham and
Karp \cite{taocp} independently discovered that the tape merge algorithm is
optimal in the worst case when the two lists have the same size. In the seminal
papers, Stockmeyer and Yao\cite{yao}, Murphy and Paull\cite{3k3}, and
Christen\cite{christen1978optimality} independently showed when the lists to be
merged are of size $m$ and $n$ satisfying $m\leq
n\leq\lfloor\frac{3}{2}m\rfloor+1$, the tape merge algorithm is optimal in the
worst case. This paper extends this result by showing that the tape merge
algorithm is optimal in the worst case whenever the size of one list is no
larger than 1.52 times the size of the other. The main tool we used to prove
lower bounds is Knuth's adversary methods \cite{taocp}. In addition, we show
that the lower bound cannot be improved to 1.8 via Knuth's adversary methods.
We also develop a new inequality about Knuth's adversary methods, which might
be interesting in its own right. Moreover, we design a simple procedure to
achieve constant improvement of the upper bounds for $2m-2\leq n\leq 3m $.


title: Mixed Hodge structures and formality

abstract:
  We prove a formality theorem for algebraic objects internal to smooth complex
varieties that are not compact but whose mixed Hodge structure has a certain
purity property.


title: Ratchet Baryogenesis with an Analogy to the Forced Pendulum

abstract:
  A new scenario of baryogenesis via the ratchet mechanism is proposed based on
an analogy to the forced pendulum. The oscillation of the inflaton field during
the reheating epoch after inflation plays the role of the driving force, while
the phase $\theta$ of a scalar baryon field (a complex scalar field with baryon
number) plays the role of the angle of the pendulum. When the inflaton is
coupled to the scalar baryon, the behavior of the phase $\theta$ can be
analogous to that of the angle of the forced pendulum. If the oscillation of
the driving force is adjusted to the pendulum's motion, a directed rotation of
the pendulum is obtained with a non-vanishing value of $\dot{\theta}$, which
models successful baryogenesis since $\dot{\theta}$ is proportional to the
baryon number density. Similar ratchet models which lead to directed motion
have been used in the study of molecular motors in biology. There, the driving
force is supplied by chemical reactions, while in our scenario this role is
played by the inflaton during the reheating epoch. Keywords: Baryogenesis;
Reheating; Inflaton; Ratchet Model; Forced Rotating Pendulum


title:
Separate chemical freeze-outs of strange and non-strange hadrons and
  problem of residual chemical non-equilibrium of strangeness in relativistic
  heavy ion collisions

abstract:
  We present an elaborate version of the hadron resonance gas model with the
combined treatment of separate chemical freeze-outs for strange and non-strange
hadrons and with an additional $\gamma_{s}$ factor which accounts for the
remaining strange particle non-equilibration. Within suggested approach the
parameters of two chemical freeze-outs are connected by the conservation laws
of entropy, baryonic charge, third isospin projection and strangeness. The
developed model enables us to perform a high-quality fit of the hadron
multiplicity ratios measured at AGS, SPS and RHIC with $\chi^2/dof \simeq
0.93$. A special attention is paid to a successful description of the
Strangeness Horn. The well-known problem of selective suppression of $\bar
\Lambda $ and $\bar \Xi$ hyperons is also discussed. The main result is that
for all collision energies the $\gamma_{s}$ factor is about 1 within the error
bars, except for the center of mass collision energy 7.6 GeV at which we find
about 20\% enhancement of strangeness. Also we confirm an existence of strong
jumps in pressure, temperature and effective number of degrees of freedom at
the stage of strange particle chemical freeze-out, when the center of mass
collision energy changes from 4.3 to 4.9 GeV. We argue that these
irregularities may signal about the quark-hadron phase transition.


title: Schauder estimates at the boundary for sub-laplacians in Carnot groups

abstract:
  In this paper we prove Schauder estimates at the boundary for sub-Laplacian
type operators in Carnot groups. While internal Schauder estimates have been
deeply studied, up to now subriemannian estimates at the boundary are known
only in the Heisenberg groups. The proof of these estimates in the Heisenberg
setting, due to Jerison, is based on the Fourier transform technique and can
not be repeated in general Lie groups. After the result of Jerison no new
contribution to the boundary problem has been provided. In this paper we
introduce a new approach, which allows to built a Poisson kernel starting from
the fundamental solution, from which we deduce the Schauder estimates at non
characteristic boundary points.


title: A highly accurate {\it ab initio} potential energy surface for methane

abstract:
  A new nine-dimensional potential energy surface (PES) for methane has been
generated using state-of-the-art \textit{ab initio} theory. The PES is based on
explicitly correlated coupled cluster calculations with extrapolation to the
complete basis set limit and incorporates a range of higher-level additive
energy corrections. These include: core-valence electron correlation,
higher-order coupled cluster terms beyond perturbative triples, scalar
relativistic effects and the diagonal Born-Oppenheimer correction.
Sub-wavenumber accuracy is achieved for the majority of experimentally known
vibrational energy levels with the four fundamentals of $^{12}$CH$_4$
reproduced with a root-mean-square error of $0.70{\,}$cm$^{-1}$. The computed
\textit{ab initio} equilibrium C{--}H bond length is in excellent agreement
with previous values despite pure rotational energies displaying minor
systematic errors as $J$ (rotational excitation) increases. It is shown that
these errors can be significantly reduced by adjusting the equilibrium
geometry. The PES represents the most accurate \textit{ab initio} surface to
date and will serve as a good starting point for empirical refinement.


title: Quantum coherence in the Dynamical Casimir Effect

abstract:
  We propose to use quantum coherence as ultimate proof of quantum nature in
the radiation that appears by means of the Dynamical Casimir Effect in
experiments with superconducting microwave waveguides. We show that, unlike
previously considered measurements of quantum correlations such as entanglement
and discord, quantum coherence does not require a threshold value of the
external pump amplitude and is highly robust to thermal noise.


title:
Fabrication of sharp atomic force microscope probes using in-situ local
  electric field induced deposition under ambient conditions

abstract:
  We demonstrate a simple method to significantly improve the sharpness of
standard silicon probes for an atomic force microscope, or to repair a damaged
probe. The method is based on creating and maintaining a strong, spatially
localized electric field in the air gap between the probe tip and the surface
of conductive sample. Under these conditions, nanostructure growth takes place
on both the sample and the tip. The most likely mechanism is the decomposition
of atmospheric adsorbate with subsequent deposition of carbon structures. This
makes it possible to grow a spike of a few hundred nanometers in length on the
tip. We further demonstrate that probes obtained by this method can be used for
high-resolution scanning. It is important to note that all process operations
are carried out in-situ, in air and do not require the use of closed chambers
or any additional equipment beyond the atomic force microscope itself.


title:
Classic balayage of measures and subharmonic functions to a system of
  rays

abstract:
  We construct and apply the classic balayage (sweeping out) of measures and
subharmonic functions on closed system of rays in the complex plane with vertex
at the origin, including measures and subharmonic functions and infinite order.
The need for such a procedure occurs in the study of the behavior of entire and
subharmonic functions on systems of rays. The results apply to the complete
regularity of the growth of subharmonic and entire functions on a system of
rays, the study of the distribution of zeros of entire functions of exponential
type of class A, touches upon the incompleteness of exponential systems. The
paper contains a survey character sections and new results.


title: 5D Maximally Supersymmetric Yang-Mills on the Lattice

abstract:
  We provide details of the lattice construction of five-dimensional maximally
supersymmetric Yang-Mills theory. The lattice theory is supersymmetric, gauge
invariant and free from spectrum doublers. Such a supersymmetric lattice
formulation is interesting as it can be used for non-perturbative explorations
of the five-dimensional theory, which has a known gravitational dual.


title: Assisted Dictionary Learning for fMRI Data Analysis

abstract:
  Extracting information from functional magnetic resonance (fMRI) images has
been a major area of research for more than two decades. The goal of this work
is to present a new method for the analysis of fMRI data sets, that is capable
to incorporate a priori available information, via an efficient optimization
framework. Tests on synthetic data sets demonstrate significant performance
gains over existing methods of this kind.


title: Converse theorems and the local Langlands correspondence in families

abstract:
  We prove a descent criterion for certain families of smooth representations
of GL_n(F) (F a p-adic field) in terms of the gamma factors of pairs
constructed in previous work of the second author. We then use this descent
criterion, together with a theory of gamma factors for families of
representations of the Weil group W_F (developed previously by both authors),
to prove a series of conjectures, due to the first author, that give a complete
description of the integral Bernstein center in terms of Galois theory and the
local Langlands correspondence. An immediate consequence is the conjectural
"local Langlands correspondence in families" of Emerton and Helm.


title: On strict convergence of stochastic gradients

abstract:
  We discuss conditions ensuring the (strict) convergence of stochastic
gradient algorithms.


title:
$\mathcal H_2$-Quasi-Optimal Model Order Reduction for
  Quadratic-Bilinear Control Systems

abstract:
  We investigate the optimal model reduction problem for large-scale
quadratic-bilinear (QB) control systems. Our contributions are threefold.
First, we discuss the variational analysis and the Volterra series formulation
for QB systems. We then define the $\mathcal H_2$-norm for a QB system based on
the kernels of the underlying Volterra series and also propose a truncated
$\mathcal H_2$-norm. Next, we derive first-order necessary conditions for an
optimal approximation, where optimality is measured in term of the truncated
$\mathcal H_2$-norm of the error system. We then propose an iterative model
reduction algorithm, which upon convergence yields a reduced-order system that
approximately satisfies the newly derived optimality conditions. We also
discuss an efficient computation of the reduced Hessian, using the special
Kronecker structure of the Hessian of the system. We illustrate the efficiency
of the proposed method by means of several numerical examples resulting from
semi-discretized nonlinear partial differential equations and show its
competitiveness with the existing model reduction schemes for QB systems such
as moment-matching methods and balanced truncation.


title: Guidelines for designing 2D and 3D plasmonic stub resonators

abstract:
  In this work, we compare the performance of plasmonic waveguide integrated
stub resonators based on 2D metal-dielectric-metal and 3D slot waveguide (SWG)
geometries. We show that scattering matrix theory can be extended to 3D
devices, and by employing scattering matrix theory, we provide the guidelines
for designing plasmonic 2D and 3D single-stub and double-stub resonators with a
desired spectral response at the design wavelength. We provide transmission
maps of 2D and 3D double-stub resonators versus stub lengths, and we specify
the different regions on these maps that result in a minimum, a maximum, or a
plasmonically induced transparency shape in the transmission spectrum.
Radiation loss from waveguide terminations leads to a degradation of the 3D
SWG-based resonators. We illustrate improved waveguide terminations that boost
resonator properties. We verify our results with 3D finite-difference
time-domain (FDTD) simulations.


title:
Noether's theorems and conserved currents in gauge theories in the
  presence of fixed fields

abstract:
  We extend the standard construction of conserved currents for matter fields
in general relativity to general gauge theories. In the original construction
the conserved current associated with a spacetime symmetry generated by a
Killing field $h^\mu$ is given by $\sqrt{-g}\,T^{\mu\nu}h_\nu$, where
$T^{\mu\nu}$ is the energy-momentum tensor of the matter. We show that if in a
Lagrangian field theory that has gauge symmetry in the general Noetherian sense
some of the elementary fields are fixed and are invariant under a particular
infinitesimal gauge transformation, then there is a current $\mathcal{B}^\mu$
that is analogous to $\sqrt{-g}\,T^{\mu\nu}h_\nu$ and is conserved if the
non-fixed fields satisfy their Euler-Lagrange equations. The conservation of
$\mathcal{B}^\mu$ can be seen as a consequence of an identity that is a
generalization of $\nabla_\mu T^{\mu\nu}=0$ and is a consequence of the gauge
symmetry of the Lagrangian. This identity holds in any configuration of the
fixed fields if the non-fixed fields satisfy their Euler-Lagrange equations. We
also show that $\mathcal{B}^\mu$ differs from the relevant canonical Noether
current by the sum of an identically conserved current and a term that vanishes
if the non-fixed fields are on-shell. As example we discuss the case of
general, possibly fermionic, matter fields propagating in fixed gravitational
and Yang-Mills background. We find that in this case the generalization of
$\nabla_\mu T^{\mu\nu}=0$ is the Lorentz law $\nabla_\mu T^{\mu\nu} -
F^{a\nu\lambda}\mathcal{J}_{a\lambda} = 0$, which holds as a consequence of the
diffeomorphism, local Lorentz and Yang-Mills gauge symmetry of the matter
Lagrangian. As a second simple example we consider the case of general fields
propagating in a background that consists of a gravitational and a real scalar
field.


title: Skew derivations on generalized Weyl algebras

abstract:
  A wide class of skew derivations on degree-one generalized Weyl algebras
$R(a,\varphi)$ over a ring $R$ is constructed. All these derivations are
twisted by a degree-counting extensions of automorphisms of $R$. It is
determined which of the constructed derivations are $Q$-skew derivations. The
compatibility of these skew derivations with the natural ${\mathbb Z}$-grading
of $R(a,\varphi)$ is studied. Additional classes of skew derivations are
constructed for generalized Weyl algebras given by an automorphism $\varphi$ of
a finite order. Conditions that the central element $a$ that forms part of the
structure of $R(a,\varphi)$ need to satisfy for the orthogonality of pairs of
aforementioned skew derivations are derived. General constructions are
illustrated by classification of skew derivations of generalized Weyl algebras
over the polynomial ring in one variable and with a linear polynomial as the
central element.


title: Non-integer characterizing slopes for torus knots

abstract:
  A slope $p/q$ is a characterizing slope for a knot $K$ in $S^3$ if the
oriented homeomorphism type of $p/q$-surgery on $K$ determines $K$ uniquely. We
show that for each torus knot its set of characterizing slopes contains all but
finitely many non-integer slopes. This generalizes work of Ni and Zhang who
established such a result for $T_{5,2}$. Along the way we show that if two
knots $K$ and $K'$ in $S^3$ have homeomorphic $p/q$-surgeries, then for $q\geq
3$ and $p$ sufficiently large we can conclude that $K$ and $K'$ have the same
genera and Alexander polynomials. This is achieved by consideration of the
absolute grading on Heegaard Floer homology.


title: Small quenches and thermalization

abstract:
  We study the expectation values of observables and correlation functions at
long times after a global quantum quench. Our focus is on metallic (`gapless')
fermionic many-body models and small quenches. The system is prepared in an
eigenstate of an initial Hamiltonian, and the time evolution is performed with
a final Hamiltonian which differs from the initial one in the value of one
global parameter. We first derive general relations between time-averaged
expectation values of observables as well as correlation functions and those
obtained in an eigenstate of the final Hamiltonian. Our results are valid to
linear and quadratic order in the quench parameter g and generalize prior
insights in several essential ways. This allows us to develop a phenomenology
for the thermalization of local quantities up to a given order in g. Our
phenomenology is put to a test in several case studies of one-dimensional
models representative of four distinct classes of Hamiltonians: quadratic ones,
effectively quadratic ones, those characterized by an extensive set of (quasi-)
local integrals of motion, and those for which no such set is known (and
believed to be nonexistent). We show that for each of these models, all
observables and correlation functions thermalize to linear order in g. The more
local a given quantity, the longer the linear behavior prevails when increasing
g. Typical local correlation functions and observables for which the term O(g)
vanishes thermalize even to order g^2. Our results show that lowest order
thermalization of local observables is an ubiquitous phenomenon even in models
with extensive sets of integrals of motion.


title: The Bramson logarithmic delay in the cane toads equations

abstract:
  We study a nonlocal reaction-diffusion-mutation equation modeling the
spreading of a cane toads population structured by a phenotypical trait
responsible for the spatial diffusion rate. When the trait space is bounded,
the cane toads equation admits traveling wave solutions [7]. Here, we prove a
Bramson type spreading result: the lag between the position of solutions with
localized initial data and that of the traveling waves grows as (3/(2$\lambda$
*)) log t. This result relies on a present-time Harnack inequality which allows
to compare solutions of the cane toads equation to those of a Fisher-KPP type
equation that is local in the trait variable.


title: Nitrogen depletion in field red giants: mixing during the He flash?

abstract:
  We combine simultaneous constraints on stellar evolutionary status from
asteroseismology, and on nitrogen abundances derived from large spectroscopic
surveys, to follow nitrogen surface abundances all along the evolution of a
low-mass star, comparing model expectations with data. After testing and
calibrating the observed yields from the APOGEE survey, we first show that
nitrogen surface abundances follow the expected trend after the first dredge-up
occurred, i.e. that the more massive is the star the more nitrogen is enhanced.
Moreover, the behaviour of nitrogen data along the evolution confirms the
existence of non-canonical extra-mixing on the RGB for all low-mass stars in
the field. But more surprisingly, the data indicate that nitrogen has been
depleted between the RGB tip and the red clump. This may suggest that some
nitrogen has been burnt near or at the He flash episode.


title: Inference for Empirical Wasserstein Distances on Finite Spaces

abstract:
  The Wasserstein distance is an attractive tool for data analysis but
statistical inference is hindered by the lack of distributional limits. To
overcome this obstacle, for probability measures supported on finitely many
points, we derive the asymptotic distribution of empirical Wasserstein
distances as the optimal value of a linear program with random objective
function. This facilitates statistical inference (e.g. confidence intervals for
sample based Wasserstein distances) in large generality. Our proof is based on
directional Hadamard differentiability. Failure of the classical bootstrap and
alternatives are discussed. The utility of the distributional results is
illustrated on two data sets.


title:
Embeddings and the (virtual) cohomological dimension of the braid and
  mapping class groups of surfaces

abstract:
  In this paper, we make use of the relations between the braid and mapping
class groups of a compact, connected, non-orientable surface N without boundary
and those of its orientable double covering S to study embeddings of these
groups and their (virtual) cohomological dimensions. We first generalise
results of Birman and Chillingworth and of Gon\c{c}alves and Guaschi to show
that the mapping class group MCG(N ; k) of N relative to a k-point subset
embeds in the mapping class group MCG(S; 2k) of S relative to a 2k-point
subset. We then compute the cohomological dimension of the braid groups of all
compact, connected aspherical surfaces without boundary. Finally, if the genus
of N is greater than or equal to 2, we give upper bounds for the virtual
cohomological dimension of MCG(N ; k).


title: Crunch-in regime - Non-linearly driven hollow-channel plasma

abstract:
  Plasma wakefields driven inside a hollow-channel plasma are significantly
different from those driven in a homogeneous plasma. This work investigates the
scaling laws of the accelerating and focusing fields in the "crunch-in" regime.
This regime is excited due to the collapse of the electron-rings from the
channel walls onto the propagation axis of the energy-source, in its wake. This
regime is thus the non-linearly driven hollow channel, since the electron-ring
displacement is of the order of the channel radius. We present the properties
of the coherent structures in the "crunch-in" regime where the channel radius
is matched to the beam properties such that channel-edge to on-axis collapse
time has a direct correspondence to the energy source intensity. We also
investigate the physical mechanisms that underlie the "crunch-in" wakefields by
tuning the channel radius. Using a theoretical framework and results from PIC
simulations the possible applications of the "crunch-in" regime for
acceleration of positron beams with collider-scale parameters is presented.


title:
From Kinetic Theory of Multicellular Systems to Hyperbolic Tissue
  Equations: Asymptotic Limits and Computing

abstract:
  This paper deals with the analysis of the asymptotic limit toward the
derivation of macroscopic equations for a class of equations modeling complex
multicellular systems by methods of the kinetic theory. After having chosen an
appropriate scaling of time and space, a Chapman-Enskog expansion is combined
with a closed, by minimization, technique to derive hyperbolic models at the
macroscopic level. The resulting macroscopic equations show how the macroscopic
tissue behavior can be described by hyperbolic systems which seem the most
natural in this context. We propose also an asymptotic-preserving well-balanced
scheme for the one-dimensional hyperbolic model, in the two dimensional case,
we consider a time splitting method between the conservative part and the
source term where the conservative equation is approximated by the
Lax-Friedrichs scheme.


title: Learning an unknown transformation via a genetic approach

abstract:
  Recent developments in integrated photonics technology are opening the way to
the fabrication of complex linear optical interferometers. The application of
this platform is ubiquitous in quantum information science, from quantum
simulation to quantum metrology, including the quest for quantum supremacy via
the boson sampling problem. Within these contexts, the capability to learn
efficiently the unitary operation of the implemented interferometers becomes a
crucial requirement. In this letter we develop a reconstruction algorithm based
on a genetic approach, which can be adopted as a tool to characterize an
unknown linear optical network. We report an experimental test of the described
method by performing the reconstruction of a 7-mode interferometer implemented
via the femtosecond laser writing technique. Further applications of genetic
approaches can be found in other contexts, such as quantum metrology or
learning unknown general Hamiltonian evolutions.


title: Oscillating heat kernels on ultrametric spaces

abstract:
  Let $(X,d)$ be a proper ultrametric space. Given a measure $m$ on $X$ and a
function $B \mapsto C(B)$ defined on the collection of all non-singleton balls
$B$ of $X$, we consider the associated hierarchical Laplacian $L=L_{C}\,$. The
operator $L$ acts in $\mathcal{L}^{2}(X,m),$ is essentially self-adjoint and
has a pure point spectrum. It admits a continuous heat kernel
$\mathfrak{p}(t,x,y)$ with respect to $m$. We consider the case when $X$ has a
transitive group of isometries under which the operator $L$ is invariant and
study the asymptotic behaviour of the function $t\mapsto
\mathfrak{p}(t,x,x)=\mathfrak{p}(t)$. It is completely monotone, but does not
vary regularly. When $X=\mathbb{Q}_{p}\,$, the ring of $p$-adic numbers, and
$L=\mathcal{D}^{\alpha} $, the operator of \ fractional derivative of order
$\alpha,$ we show that $\mathfrak{p}(t)=t^{-1/\alpha}\mathcal{A}% (\log_{p}t)$,
where $\mathcal{A}(\tau)$ is a continuous non-constant $\alpha$-periodic
function. We also study asymptotic behaviour of $\min\mathcal{A}$ and
$\max\mathcal{A}$ as the space parameter $p$ tends to $\infty$. When
$X=S_{\infty}\,$, the infinite symmetric group, and $L$ is a hierarchical
Laplacian with metric structure analogous to $\mathcal{D}^{\alpha},$ we show
that, contrary to the previous case, the completely monotone function
$\mathfrak{p}(t)$ oscillates between two functions $\psi(t)$ and $\Psi(t)$ such
that $\psi(t)/\Psi(t)\to 0$ as $t \to \infty\,$.


title: Few-particle systems: An analysis of some strongly correlated states

abstract:
  The analysis of the quantum Hall response of a small system of ultracold
bosonic atoms through the variation of its Hall resistivity against the applied
gauge magnetic field, provides a powerful method to unmask its strongly
correlated states in a quite eshaustive way. Within a fixed range of values of
the magnetic field in the lowest Landau-level regime, where the resistivity
displays two successive plateaux, we identify the implied states as the
Pfaffian and the state with filling factor \nu=2/3 in the thermodynamic limit.
We fix the conditions to have good observability.


title: Observer's observables. Residual diffeomorphisms

abstract:
  We investigate the fate of diffeomorphisms when the radial gauge is imposed
in canonical general relativity. As shown elsewhere, the radial gauge is
closely related to the observer's observables. These observables are invariant
under a large subgroup of diffeomorphisms which results in their usefulness for
canonical general relativity. There are, however, some diffeomorphisms, called
residual diffeomorphisms, which might be "observed" by the observer as they do
not preserve her observables. The present paper is devoted to the analysis of
these diffeomorphisms in the case of the spatial and spacetime radial gauges.
Although the residual diffeomorphisms do not form a subgroup of all
diffeomorphisms, we show that their induced action in the phase space does form
a group. We find the generators of the induced transformations and compute the
structure functions of the algebras they form. The obtained algebras are
deformations of the algebra of the Euclidean group and the algebra of the
Poincar\'e group in the spatial and spacetime case, respectively. In both cases
the deformation depends only on the Riemann curvature tensor and in particular
vanishes when the space or spacetime is flat.


title: Safe, Multi-Agent, Reinforcement Learning for Autonomous Driving

abstract:
  Autonomous driving is a multi-agent setting where the host vehicle must apply
sophisticated negotiation skills with other road users when overtaking, giving
way, merging, taking left and right turns and while pushing ahead in
unstructured urban roadways. Since there are many possible scenarios, manually
tackling all possible cases will likely yield a too simplistic policy.
Moreover, one must balance between unexpected behavior of other
drivers/pedestrians and at the same time not to be too defensive so that normal
traffic flow is maintained.
  In this paper we apply deep reinforcement learning to the problem of forming
long term driving strategies. We note that there are two major challenges that
make autonomous driving different from other robotic tasks. First, is the
necessity for ensuring functional safety - something that machine learning has
difficulty with given that performance is optimized at the level of an
expectation over many instances. Second, the Markov Decision Process model
often used in robotics is problematic in our case because of unpredictable
behavior of other agents in this multi-agent scenario. We make three
contributions in our work. First, we show how policy gradient iterations can be
used without Markovian assumptions. Second, we decompose the problem into a
composition of a Policy for Desires (which is to be learned) and trajectory
planning with hard constraints (which is not learned). The goal of Desires is
to enable comfort of driving, while hard constraints guarantees the safety of
driving. Third, we introduce a hierarchical temporal abstraction we call an
"Option Graph" with a gating mechanism that significantly reduces the effective
horizon and thereby reducing the variance of the gradient estimation even
further.


title:
A panorama of dispersion curves for the weighted isotropic relaxed
  micromorphic model

abstract:
  We consider the weighted isotropic relaxed micromorphic model and provide an
in depth investigation of the characteristic dispersion curves when the
constitutive parameters of the model are varied. The weighted relaxed
micromorphic model generalizes the classical relaxed micromorphic model
previously introduced by the authors, since it features the Cartan-Lie
decomposition of the tensors $P_{,t}$ and Curl $P$ in their dev, dev sym, skew
and spheric part. It is shown that the split of the tensor $P_{,t}$ in the
micro-inertia provide an independent control of the cut-offs of the optic
benches. This is crucial for the future calibration of the relaxed micromorphic
model on real band-gap metamaterials.
  Even if the physical interest of the introduction of the split of the tensor
Curl $P$ is less evident than in the previous case, we discuss in detail which
is its effect on the dispersion curves. Finally, we also provide a complete
parametric study involving all the constitutive parameters of the introduced
model, so giving rise to an exhaustive panorama of dispersion curves for the
relaxed micromorphic model.


title:
Real submanifolds of maximum complex tangent space at a CR singular
  point, II

abstract:
  We study a germ of real analytic n-dimensional submanifold of $C^n$ that has
a complex tangent space of maximal dimension at a CR singularity. Under the
condition that its complexification admits the maximum number of deck
transformations, we first classify holomorphically its quadratic CR
singularity. We then study its transformation to a normal form under the action
of local (possibly formal) biholomorphisms at the singularity. We first
conjugate formally its associated reversible map $\sigma$ to suitable normal
forms and show that all these normal forms can be divergent. We then construct
a unique formal normal form under a non degeneracy condition.


title: Combining Treewidth and Backdoors for CSP

abstract:
  We show that CSP is fixed-parameter tractable when parameterized by the
treewidth of a backdoor into any tractable CSP problem over a finite constraint
language. This result combines the two prominent approaches for achieving
tractability for CSP: (i) by structural restrictions on the interaction between
the variables and the constraints and (ii) by language restrictions on the
relations that can be used inside the constraints. Apart from defining the
notion of backdoor-treewidth and showing how backdoors of small treewidth can
be used to efficiently solve CSP, our main technical contribution is a
fixed-parameter algorithm that finds a backdoor of small treewidth.


title: Small slot waveguide rings for on-chip quantum optical circuits

abstract:
  Nanophotonic interfaces between single emitters and light promise to enable
new quantum optical technologies. Here, we use a combination of finite element
simulations and analytic quantum theory to investigate the interaction of
various quantum emitters with slot-waveguide rings. We predict that for rings
with radii as small as 1.44 $\mu$m (Q = 27,900), near-unity emitter-waveguide
coupling efficiencies and emission enhancements on the order of 1300 can be
achieved. By tuning the ring geometry or introducing losses, we show that
realistic emitter-ring systems can be made to be either weakly or strongly
coupled, so that we can observe Rabi oscillations in the decay dynamics even
for micron-sized rings. Moreover, we demonstrate that slot waveguide rings can
be used to directionally couple emission, again with near-unity efficiency. Our
results pave the way for integrated solid-state quantum circuits involving
various emitters.


title:
Stability, convergence to equilibrium and simulation of non-linear
  Hawkes Processes with memory kernels given by the sum of Erlang kernels

abstract:
  Non-linear Hawkes processes with memory kernels given by the sum of Erlang
kernels are considered. It is shown that their stability properties can be
studied in terms of an associated class of piecewise deterministic Markov
processes, called Markovian cascades of successive memory terms. Explicit
conditions implying the positive Harris recurrence of these processes are
presented. The proof is based on integration by parts with respect to the jump
times. A crucial property is the non-degeneracy of the transition semigroup
which is obtained thanks to the invertibility of an associated Vandermonde
matrix. For Lipschitz continuous rate functions we also show that these
Markovian cascades converge to equilibrium exponentially fast with respect to
the Wasserstein distance. Finally, an extension of the classical thinning
algorithm is proposed to simulate such Markovian cascades.


title: An analogue to Dixon's theorem for automaton groups

abstract:
  Dixon's famous theorem states that the group generated by two random
permutations of a finite set is generically either the whole symmetric group or
the alternating group. In the context of random generation of finite groups
this means that it is hopeless to wish for a uniform distribution -- or even a
non-trivial one -- by drawing random permutations and looking at the generated
group. Mealy automata are a powerful tool to generate groups, including all
finite groups and many interesting infinite ones, whence the idea of generating
random finite groups by drawing random Mealy automata. In this paper we show
that, for a special class of Mealy automata that generate only finite groups,
the distribution is far from being uniform since the obtained groups are
generically a semi-direct product between a direct product of alternating
groups and a group generated by a tuple of transpositions.


title:
The universal C*-algebra of the electromagnetic field II. Topological
  charges and spacelike linear fields

abstract:
  Conditions for the appearance of topological charges are studied in the
framework of the universal C*-algebra of the electromagnetic field, which is
represented in any theory describing electromagnetism. It is shown that
non-trivial topological charges, described by pairs of fields localised in
certain topologically non-trivial spacelike separated regions, can appear in
regular representations of the algebra only if the fields depend non-linearly
on the mollifying test functions. On the other hand, examples of regular vacuum
representations with non-trivial topological charges are constructed, where the
underlying field still satisfies a weakened form of "spacelike linearity". Such
representations also appear in the presence of electric currents. The status of
topological charges in theories with several types of electromagnetic fields,
which appear in the short distance (scaling) limit of asymptotically free
non-abelian gauge theories, is also briefly discussed.


title: The Phase Transition in 5 Point Energy Minimization

abstract:
  Let R_s(r)=sign(s)/r^s be the Riesz s-energy potential. (This is the usual
power-law potential.) This monograph proves the existence of a computable
number S=15.048... such that the triangular bi-pyramid is the unique minimizer
with respect to R_s, amongst all 5-point configurations on the sphere, if and
only if s lies in (-2,0) or (0,S). This establishes the existence of the
long-conjectured phase transition constant in 5-point energy minimization.


title:
Inflation via logarithmic entropy-corrected holographic dark energy
  model

abstract:
  We study the inflation via logarithmic entropy-corrected holographic dark
energy LECHDE model with future event horizon, particle horizon and Hubble
horizon cut-offs, and compare the results with those of obtained in the study
of inflation by holographic dark energy HDE model. In comparison, the spectrum
of primordial scalar power spectrum in the LECHDE model becomes redder than the
spectrum in HDE model. Moreover, the consistency with the observational data in
LECHDE model of inflation, constrains the reheating temperature and Hubble
parameter by one parameter of holographic dark energy and two new parameters of
logarithmic corrections.


title: Model Based In Situ Calibration of Six Axis Force Torque Sensors

abstract:
  This paper proposes and validates an in situ calibration method to calibrate
six axis force torque (F/T) sensors once they are mounted on the system. This
procedure takes advantage of the knowledge of the model of the robot to
generate the expected wrenches of the sensors during some arbitrary motions. It
then uses this information to train and validate new calibration matrices,
taking into account the calibration matrix obtained with a classical Workbench
calibration. The proposed calibration algorithm is validated on the F/T sensors
mounted on the iCub humanoid robot legs.


title: Projective dimension and regularity of path ideals of cycles

abstract:
  In this paper, we give a formula to compute all the top degree graded Betti
numbers of the path ideals of a cycle. As a consequence we can give a formula
to compute its projective dimension and regularity.


title: Ball Intersection Properties in Metric Spaces

abstract:
  We show that in complete metric spaces, $4$-hyperconvexity is equivalent to
finite hyperconvexity. Moreover, every complete, almost $n$-hyperconvex metric
space is $n$-hyperconvex. This generalizes among others results of
Lindenstrauss and answers questions of Aronszajn-Panitchpakdi.
  Furthermore, we prove local-to-global results for externally and weakly
externally hyperconvex subsets of hyperconvex metric spaces and find sufficient
conditions in order for those classes of subsets to be convex with respect to a
geodesic bicombing.


title:
Exact ensemble density functional theory for excited states in a model
  system: investigating the weight dependence of the correlation energy

abstract:
  Ensemble density functional theory (eDFT) is an exact time-independent
alternative to time-dependent DFT (TD-DFT) for the calculation of excitation
energies. Despite its formal simplicity and advantages in contrast to TD-DFT
(multiple excitations, for example, can be easily taken into account in an
ensemble), eDFT is not standard which is essentially due to the lack of
reliable approximate exchange-correlation (xc) functionals for ensembles.
Following Smith et al. [Phys. Rev. B 93, 245131 (2016)], we propose in this
work to construct an exact eDFT for the nontrivial asymmetric Hubbard dimer,
thus providing more insight into the weight dependence of the ensemble xc
energy in various correlation regimes. For that purpose, an exact analytical
expression for the weight-dependent ensemble exchange energy has been derived.
The complementary exact ensemble correlation energy has been computed by means
of Legendre--Fenchel transforms. Interesting features like discontinuities in
the ensemble xc potential in the strongly correlated limit have been
rationalized by means of a generalized adiabatic connection formalism. Finally,
functional-driven errors induced by ground-state density-functional
approximations have been studied. In the strictly symmetric case or in the
weakly correlated regime, combining ensemble exact exchange with ground-state
correlation functionals gives relatively accurate ensemble energies. However,
when approaching the equiensemble in the strongly correlated regime, this
approximation leads to highly curved ensemble energies with negative slope
which is unphysical. Using both ground-state exchange and correlation
functionals gives much better results in that case. In fact, exact ensemble
energies are almost recovered in some density domains. The analysis of
density-driven errors is left for future work.


title:
A Low-Overhead Hybrid Approach for Universal Fault-Tolerant Quantum
  Computation

abstract:
  As there is no quantum error correction code with universal set of
transversal gates, several approaches have been proposed which, in combination
of transversal gates, make universal fault-tolerant quantum computation
possible. Magic state distillation, code switching, code concatenation and
pieceable fault-tolerance are well-known examples of such approaches. However,
the overhead of these approaches is one of the main bottlenecks for large-scale
quantum computation. In this paper, a hybrid approach is proposed which
combines the code concatenation technique with the other mentioned approaches.
The proposed approach outperforms code concatenation in terms of both number of
qubits and error threshold and also significantly reduces the resource overhead
of code switching, magic state distillation and pieceable fault-tolerance at
the cost of reducing the effective distance of the concatenated code for
implementing non-transversal gates.


title:
The Relativistic Hamilton-Jacobi Equation for a Massive, Charged and
  Spinning Particle, its Equivalent Dirac Equation and the de Broglie-Bohm
  Theory

abstract:
  Using the Clifford and the Spin-Clifford formalisms we prove that the
classical relativistic Hamilton Jacobi equation for a charged massive (and
spinning) particle interacting with an external electromagnetic field is
equivalent to a Dirac-Hestenes equation satisfied by a class of spinor fields
that we call classical spinor fields, characterized for having the Takabayashi
angle function constant (equal to 0 or {\pi}). We also investigate a nonlinear
Dirac-Hestenes like equation that comes from some class of generalized
classical spinor fields. Finally we show that the general Dirac-Hestenes
equation (which is a representative in the Clifford bundle of the usual Dirac
equation) gives a generalized Hamilton-Jacobi equation where the quantum
potential satisfy a severe constraint and the "mass of the particle" becomes a
variable. Our results can then explain the experimental discrepancies found
between prediction of the de Broglie-Bohm theory and recent experiments. We
briefly discuss also the de Broglie's double solution theory in view of our
results showing that it can be realized, at least in the case of spinning free
particles..The paper contains several Appendices where notation and proofs of
some results of the text are presented.


title:
Characterizing the gamma-ray long-term variability of PKS 2155-304 with
  H.E.S.S. and Fermi-LAT

abstract:
  Studying the temporal variability of BL Lac objects at the highest energies
provides unique insights into the extreme physical processes occurring in
relativistic jets and in the vicinity of super-massive black holes. To this
end, the long-term variability of the BL Lac object PKS 2155-304 is analyzed in
the high (HE, 100 MeV < E < 300 GeV) and very high energy (VHE, E > 200 GeV)
gamma-ray domain. Over the course of ~9 yr of H.E.S.S observations the VHE
light curve in the quiescent state is consistent with a log-normal behavior.
The VHE variability in this state is well described by flicker noise
(power-spectral-density index {\ss}_VHE = 1.10 +0.10 -0.13) on time scales
larger than one day. An analysis of 5.5 yr of HE Fermi LAT data gives
consistent results ({\ss}_HE = 1.20 +0.21 -0.23, on time scales larger than 10
days) compatible with the VHE findings. The HE and VHE power spectral densities
show a scale invariance across the probed time ranges. A direct linear
correlation between the VHE and HE fluxes could neither be excluded nor firmly
established. These long-term-variability properties are discussed and compared
to the red noise behavior ({\ss} ~ 2) seen on shorter time scales during
VHE-flaring states. The difference in power spectral noise behavior at VHE
energies during quiescent and flaring states provides evidence that these
states are influenced by different physical processes, while the compatibility
of the HE and VHE long-term results is suggestive of a common physical link as
it might be introduced by an underlying jet-disk connection.


title:
Nuclear magnetic resonance study of the magnetic-field-induced ordered
  phase in the NiCl2-4SC(NH2)2 compound

abstract:
  Nuclear magnetic resonance (NMR) study of the high magnetic field (H) part of
the Bose-Einstein condensed (BEC) phase of the quasi-onedimensional (quasi-1D)
antiferromagnetic quantum spin-chain compound NiCl2-4SC(NH2)2 (DTN) was
performed. We precisely determined the phase boundary, Tc(H), down to 40 mK;
the critical boson density, n_c(Tc); and the absolute value of the BEC order
parameter S_perp at very low temperature (T = 0.12 K). All results are
accurately reproduced by numerical quantum Monte Carlo simulations of a
realistic three-dimensional (3D) model Hamiltonian. Approximate analytical
predictions based on the 1D Tomonaga-Luttinger liquid description are found to
be precise for Tc(H), but less so for S_perp(H), which is more sensitive to the
strength of 3D couplings, in particular close to the critical field. A
mean-field treatment, based on the Hartree-Fock-Popov description, is found to
be valid only up to n_c = 4% (T < 0.3 K), while for higher n_c boson
interactions appear to modify the density of states.


title:
Stability Limits and Surface Chemistry of Ag Nanoparticles in
  Non-Adsorbing Electrolytes Probed by Bragg Coherent Diffractive Imaging

abstract:
  Surface chemistry is important across diverse fields such as corrosion and
nanostructure synthesis. Unfortunately, many as-synthesized nanomaterials,
including partially dealloyed nanoparticle catalysts for fuel cells, with
highly active surfaces are not stable in their reactive environments,
preventing widespread application. Thus, understanding instability by focusing
on the structure-stability and defect-stability relationship at the nanoscale
is crucial and will likely play an important role in meeting grand challenges.
To this end, recent advances in imaging nanostructure stability have come via
both electron, x-ray, and other techniques such as atomic force microscopy, but
tend to be limited to specific sample environments and/or two-dimensional
images. Here, we report investigations into the defect-stability relationship
of silver nanoparticles to voltage-induced electrochemical dissolution imaged
in-situ in three-dimensional (3D) detail by Bragg Coherent Diffractive Imaging
(BCDI). We first determine the average dissolution kinetics by Stationary Probe
Rotating Disk Electrode (SPRDE) in combination with inductively coupled plasma
mass spectrometry (ICP-MS), which allows real-time in-situ measurement of Ag+
ions formation and the corresponding electrochemical current. We then observe
the dissolution and redeposition processes in 3D with BCDI in single
nanocrystals, providing unique insight about the role of surface strain,
defects, and their coupling to the dissolution chemistry. The methods developed
and the knowledge gained go well beyond a "simple" silver electrochemistry and
are applicable to all electrocatalytic reactions where functional links between
activity and stability are controlled by structure and defect dynamics.


title:
Spontaneous particle-hole symmetry breaking of correlated fermions on
  the Lieb lattice

abstract:
  We study spinless fermions with nearest-neighbor repulsive interactions
($t$-$V$ model) on the two-dimensional three-band Lieb lattice. At
half-filling, the free electronic band structure consists of a flat band at
zero energy and a single cone with linear dispersion. The flat band is expected
to be unstable upon inclusion of electronic correlations, and a natural channel
is charge order. However, due to the three-orbital unit cell, commensurate
charge order implies an imbalance of electron and hole densities and therefore
doping away from half-filling. Our numerical results show that below a
finite-temperature Ising transition a charge density wave with one electron and
two holes per unit cell and its partner under particle-hole transformation are
spontaneously generated. Our calculations are based on recent advances in
auxiliary-field and continuous-time quantum Monte Carlo simulations that allow
sign-free simulations of spinless fermions at half-filling. It is argued that
particle-hole symmetry breaking provides a route to access levels of finite
doping, without introducing a sign problem.


title:
Lorentz-violating neutral-pion decays in isotropic modified Maxwell
  theory

abstract:
  We consider an extension of the Standard Model with isotropic nonbirefringent
Lorentz violation in the photon sector and restrict the discussion to the case
of a "fast" photon with a phase velocity larger than the maximum attainable
velocity of the quarks and leptons. With our conventions, this case corresponds
to a negative Lorentz-violating parameter $\kappa$ in the action. The decay
rate of a neutral pion into two nonstandard photons is calculated as a function
of the 3-momentum of the initial pion and the negative Lorentz-violating
parameter $\kappa$ of the final photons.


title:
Learning from Survey Training Samples: Rate Bounds for Horvitz-Thompson
  Risk Minimizers

abstract:
  The generalization ability of minimizers of the empirical risk in the context
of binary classification has been investigated under a wide variety of
complexity assumptions for the collection of classifiers over which
optimization is performed. In contrast, the vast majority of the works
dedicated to this issue stipulate that the training dataset used to compute the
empirical risk functional is composed of i.i.d. observations. Beyond the cases
where training data are drawn uniformly without replacement among a large
i.i.d. sample or modelled as a realization of a weakly dependent sequence of
r.v.'s, statistical guarantees when the data used to train a classifier are
drawn by means of a more general sampling/survey scheme and exhibit a complex
dependence structure have not been documented yet. It is the main purpose of
this paper to show that the theory of empirical risk minimization can be
extended to situations where statistical learning is based on survey samples
and knowledge of the related inclusion probabilities. Precisely, we prove that
minimizing a weighted version of the empirical risk, refered to as the
Horvitz-Thompson risk (HT risk), over a class of controlled complexity lead to
a rate for the excess risk of the order $O_{\mathbb{P}}((\kappa_N (\log
N)/n)^{1/2})$ with $\kappa_N=(n/N)/\min_{i\leq N}\pi_i$, when data are sampled
by means of a rejective scheme of (deterministic) size $n$ within a statistical
population of cardinality $N\geq n$, a generalization of basic {\it sampling
without replacement} with unequal probability weights $\pi_i>0$. Extension to
other sampling schemes are then established by a coupling argument. Beyond
theoretical results, numerical experiments are displayed in order to show the
relevance of HT risk minimization and that ignoring the sampling scheme used to
generate the training dataset may completely jeopardize the learning procedure.


title: A Greedy Approach for Budgeted Maximum Inner Product Search

abstract:
  Maximum Inner Product Search (MIPS) is an important task in many machine
learning applications such as the prediction phase of a low-rank matrix
factorization model for a recommender system. There have been some works on how
to perform MIPS in sub-linear time recently. However, most of them do not have
the flexibility to control the trade-off between search efficient and search
quality. In this paper, we study the MIPS problem with a computational budget.
By carefully studying the problem structure of MIPS, we develop a novel
Greedy-MIPS algorithm, which can handle budgeted MIPS by design. While simple
and intuitive, Greedy-MIPS yields surprisingly superior performance compared to
state-of-the-art approaches. As a specific example, on a candidate set
containing half a million vectors of dimension 200, Greedy-MIPS runs 200x
faster than the naive approach while yielding search results with the top-5
precision greater than 75\%.


title:
Determination of hole g-factor in InAs/InGaAs/InAlAs quantum wells by
  magneto-photoluminescence studies

abstract:
  Circularly-polarized magneto-photoluminescence (magneto-PL) technique has
been applied to investigate Zeeman effect in InAs/InGaAs/InAlAs quantum wells
(QWs) in Faraday geometry. Structures with different thickness of the QW
barriers have been studied in magnetic field parallel and tilted with respect
to the sample normal. Effective electron-hole g-factor has been found by
measurement of splitting of polarized magneto-PL lines. Lande factors of
electrons have been calculated using the 14-band kp method and g-factor of
holes was determined by subtracting the calculated contribution of the
electrons from the effective electron-hole g-factor. Anisotropy of the hole
g-factor has been studied applying tilted magnetic field.


title:
A locally p-adaptive approach for Large Eddy Simulation of compressible
  flows in a DG framework

abstract:
  We investigate the possibility of reducing the computational burden of LES
models by employing local polynomial degree adaptivity in the framework of a
high order DG method. A novel degree adaptation technique especially featured
to be effective for LES applications is proposed and its effectiveness is
compared to that of other criteria already employed in the literature. The
resulting locally adaptive approach allows to achieve significant reductions in
computational cost of representative LES computations.


title:
The Galactic O-Star Catalog (GOSC) and the Galactic O-Star Spectroscopic
  Survey (GOSSS): current status

abstract:
  We present the updates of the Galactic O-Star Catalog (GOSC) that we have
undertaken in the last two years: new spectral types, more objects, additional
information, and coordination with CDS. We also present updates for the
Galactic O-Star Spectroscopic Survey (GOSSS). A new paper (GOSSS-III) has been
published and ~1000 targets have been observed since 2014. Four new setups have
been added to our lineup and for two of them we have already obtained over 100
spectra: with OSIRIS at the 10.4 m GTC we are observing northern dim stars and
with FRODOspec at the 2.0 m Liverpool Telescope we are observing northern
bright stars. Finally, we also make available new versions of MGB, the spectral
classification tool associated with the project, and of the GOSSS grid of
spectroscopic standards.


title: Keystroke dynamics as signal for shallow syntactic parsing

abstract:
  Keystroke dynamics have been extensively used in psycholinguistic and writing
research to gain insights into cognitive processing. But do keystroke logs
contain actual signal that can be used to learn better natural language
processing models?
  We postulate that keystroke dynamics contain information about syntactic
structure that can inform shallow syntactic parsing. To test this hypothesis,
we explore labels derived from keystroke logs as auxiliary task in a multi-task
bidirectional Long Short-Term Memory (bi-LSTM). Our results show promising
results on two shallow syntactic parsing tasks, chunking and CCG supertagging.
Our model is simple, has the advantage that data can come from distinct
sources, and produces models that are significantly better than models trained
on the text annotations alone.


title: Optimal parameters uncoupling vibration modes of oscillators

abstract:
  A novel optimization concept for an oscillator with two degrees of freedom is
proposed. By using specially defined motion ratios, we control the action of
springs and dampers to each degree of freedom of the oscillator. If the
potential action of the springs in one period of vibration, used as the payoff
function for the conservative oscillator, is maximized, then the optimal motion
ratios uncouple vibration modes. The same result holds true for the dissipative
oscillator. The application to optimal design of vehicle suspension is
discussed.


title:
How the nonlinear coupled oscillators modelization explains the Blazhko
  effect, the synchronisation of layers, the mode selection, the limit cycle,
  and the red limit of the instability strip

abstract:
  Context. The Blazhko effect, in RR Lyrae type stars, is a century old
mystery. Dozens of theory exists, but none have been able to entirely reproduce
the observational facts associated to this modulation phenomenon. Existing
theory all rely on the usual continuous modelization of the star. Aims. We
present a new paradigm which will not only explain the Blazhko effect, but at
the same time, will give us alternative explanations to the red limit of the
instability strip, the synchronization of layers, the mode selection and the
existence of a limit cycle for radially pulsating stars. Methods. We describe
the RR Lyrae type pulsating stars as a system of coupled nonlinear oscillators.
Considering a spatial discretisation of the star, supposing a spherical
symmetry, we develop the equation of motion and energy up to the third order in
the radial and adiabatic case. Then, we include the influence of the ionization
region as a relaxation oscillator by including elements from synchronisation
theory. Results. This discrete approach allows us to exploit existing results
in the coupled nonlinear oscillator field. For instance, the study of
synchronicity leads to an explanation of the mode selection, the layers
synchronisation, the limit cycle and the red limit of the instability strip.
But, most of all, the analogy with the Fermi-Pasta-Ulam (FPU) experiment
enables us to understand the Blazhko effect. The transfer of energy between
different modes, as induced by solitons, not only gives a plausible theory for
lightcurve modulation, but also explains the asymmetry of sidelobes.


title: A grid of 1D low-mass star formation collapse models

abstract:
  The current study was developed to provide a database of relatively simple
numerical simulations of protostellar collapse, as a template library for
observations of cores and very young protostars, and for researchers who wish
to test their chemical modeling under dynamic astrophysical conditions. It was
also designed to identify statistical trends that may appear when running many
models of the formation of low-mass stars by varying the initial conditions. A
large set of 143 calculations of the gravitational collapse of an isolated
sphere of gas with uniform temperature and a Bonnor-Ebert like density profile
was undertaken using a 1D fully implicit Lagrangian radiation hydrodynamics
code. The parameter space covered initial masses from 0.2 to 8 Msun,
temperatures of 5-30 K and radii between 3000 and 30,000 AU. A spread in the
thermal evolutionary tracks of the runs was found, due to differing initial
conditions and optical depths. Within less than an order of magnitude, all
first and second Larson cores had masses and radii independent of the initial
conditions. The time elapsed between the formation of the first and second
cores was found to strongly depend on the first core mass accretion rate, and
no first core in our grid of models lived for longer than 2000 years, before
the onset of the second collapse. The end product of a protostellar cloud
collapse, the second Larson core, is, at birth, a canonical object with a mass
and radius of about 3 Mjup and 8 Rjup, independent of its initial conditions.
The evolution sequence which brings the gas to stellar densities can however
proceed in a variety of scenarios, on different timescales, along different
isentropes, but each story line can largely be predicted by the initial
conditions. All the data from the simulations are publicly available at this
address: http://starformation.hpc.ku.dk/grid-of-protostars.


title: High temperature condensate clouds in super-hot Jupiter atmospheres

abstract:
  Deciphering the role of clouds is central to our understanding of exoplanet
atmospheres, as they have a direct impact on the temperature and pressure
structure, and observational properties of the planet. Super-hot Jupiters
occupy a temperature regime similar to low mass M-dwarfs, where minimal cloud
condensation is expected. However, observations of exoplanets such as WASP-12b
(Teq ~ 2500 K) result in a transmission spectrum indicative of a cloudy
atmosphere. We re-examine the temperature and pressure space occupied by these
super-hot Jupiter atmospheres, to explore the role of the initial Al- and
Ti-bearing condensates as the main source of cloud material. Due to the high
temperatures a majority of the more common refractory material is not depleted
into deeper layers and would remain in the vapor phase. The lack of depletion
into deeper layers means that these materials with relatively low cloud masses
can become significant absorbers in the upper atmosphere. We provide
condensation curves for the initial Al- and Ti-bearing condensates that may be
used to provide quantitative estimates of the effect of metallicity on cloud
masses, as planets with metal-rich hosts potentially form more opaque clouds
because more mass is available for condensation. Increased metallicity also
pushes the point of condensation to hotter, deeper layers in the planetary
atmosphere further increasing the density of the cloud. We suggest that planets
around metal-rich hosts are more likely to have thick refractory clouds, and
discuss the implication on the observed spectra of WASP-12b.


title: Stochastic continuity equation with non-smooth velocity

abstract:
  In this article we study the existence and uniqueness of solutions of
stochastic continuity equation with irregular coefficients.


title: Experimental non-locality in a quantum network

abstract:
  Non-locality stands nowadays not only as one of the cornerstones of quantum
theory, but also plays a crucial role in quantum information processing.
Several experimental investigations of nonlocality have been carried out over
the years. In spite of their fundamental relevance, however, all previous
experiments do not consider a crucial ingredient that is ubiquitous in quantum
networks: the fact that correlations between distant parties are mediated by
several, typically independent, sources of quantum states. Here, using a
photonic setup we investigate a quantum network consisting of three spatially
separated nodes whose correlations are mediated by two independent sources.
This scenario allows for the emergence of a new kind of non-local correlations
that we experimentally witness by violating a novel Bell inequality. Our
results provide the first experimental proof-of-principle of generalizations of
Bell's theorem for networks, a topic that has attracted growing attention and
promises a novel route for quantum communication protocols.


title: Moderate deviations for Ewens-Pitman exchangeable random partitions

abstract:
  Consider a population of individuals belonging to an infinity number of
types, and assume that type proportions follow the two-parameter
Poisson-Dirichlet distribution. A sample of size n is selected from the
population. The total number of different types and the number of types
appearing in the sample with a fixed frequency are important statistics. In
this paper we establish the moderate deviation principles for these quantities.
The corresponding rate functions are explicitly identified, which help
revealing a critical scale and understanding the exact role of the parameters.
Conditional, or posterior, counterparts of moderate deviation principles are
also established.


title: Magnetic resonance with squeezed microwaves

abstract:
  Vacuum fluctuations of the electromagnetic field set a fundamental limit to
the sensitivity of a variety of measurements, including magnetic resonance
spectroscopy. We report the use of squeezed microwave fields, which are
engineered quantum states of light for which fluctuations in one field
quadrature are reduced below the vacuum level, to enhance the detection
sensitivity of an ensemble of electronic spins at millikelvin temperatures.} By
shining a squeezed vacuum state on the input port of a microwave resonator
containing the spins, we obtain a $1.2$\,dB noise reduction at the spectrometer
output compared to the case of a vacuum input. This result constitutes a proof
of principle of the application of quantum metrology to magnetic resonance
spectroscopy.


title:
Detecting Multiple Replicating Signals using Adaptive Filtering
  Procedures

abstract:
  Replicability is a fundamental quality of scientific discoveries: we are
interested in those signals that are detectable in different laboratories,
study populations, across time etc. Unlike meta-analysis which accounts for
experimental variability but does not guarantee replicability, testing a
partial conjunction (PC) null aims specifically to identify the signals that
are discovered in multiple studies. In many contemporary applications, e.g.,
comparing multiple high-throughput genetic experiments, a large number $M$ of
PC nulls need to be tested simultaneously, calling for a multiple comparisons
correction. However, standard multiple testing adjustments on the $M$ PC
$p$-values can be severely conservative, especially when $M$ is large and the
signals are sparse. We introduce AdaFilter, a new multiple testing procedure
that increases power by adaptively filtering out unlikely candidates of PC
nulls. We prove that AdaFilter can control FWER and FDR as long as data across
studies are independent, and has much higher power than other existing methods.
We illustrate the application of AdaFilter with three examples: microarray
studies of Duchenne muscular dystrophy, single-cell RNA sequencing of T cells
in lung cancer tumors and GWAS for metabolomics.


title: Definable discrete sets with large continuum

abstract:
  Let $\mathcal R$ be a $\Sigma^1_1$ binary relation and call a set $\mathcal
R$-discrete iff no two distinct of its elements are $\mathcal R$-related. We
show that in the extension of $\mathbf{L}$ by iterated Sacks forcing, there is
a $\Delta^1_2$ maximal $\mathcal R$-discrete set, and thus the existence of
such sets is compatible with the negation of the continuum hypothesis. As an
application we find a $\Pi^1_1$ maximal orthogonal family of Borel probability
measures in said extension. The basis of this is a new Ramsey theoretic result.


title: Engineering a Distributed Full-Text Index

abstract:
  We present a distributed full-text index for big data applications in a
distributed environment. Our index can answer different types of pattern
matching queries (existential, counting and enumeration). We perform
experiments on inputs up to 100 GiB using up to 512 processors, and compare our
index with the distributed suffix array by Arroyuelo et al. [Parall. Comput.
40(9): 471--495, 2014]. The result is that our index answers counting queries
up to 5.5 times faster than the distributed suffix array, while using about the
same space. We also provide a succinct variant of our index that uses only one
third of the memory compared with our non-succinct variant, at the expense of
only 20% slower query times.


title: Strange quark asymmetry in the proton in chiral effective theory

abstract:
  We perform a comprehensive analysis of the strange-antistrange parton
distribution function (PDF) asymmetry in the proton in the framework of chiral
effective theory, including the full set of lowest order kaon loop diagrams
with off-shell and contact interactions, in addition to the usual on-shell
contributions previously discussed in the literature. We identify the presence
of $\delta$-function contributions to the $\bar s$ PDF at $x=0$, with a
corresponding valence-like component of the $s$-quark PDF at larger $x$, which
allows greater flexibility for the shape of $s-\bar s$. Expanding the moments
of the PDFs in terms of the pseudoscalar kaon mass, we compute the leading
nonanalytic behavior of the number and momentum integrals of the $s$ and $\bar
s$ distributions, consistent with the chiral symmetry of QCD. We discuss the
implications of our results for the understanding of the NuTeV anomaly and for
the phenomenology of strange quark PDFs in global QCD analysis.


title:
Magnetodielectric detection of magnetic quadrupole order in
  Ba(TiO)Cu$_4$(PO$_4$)$_4$ with Cu$_4$O$_{12}$ square cupolas

abstract:
  In vortex-like spin arrangements, multiple spins can combine into emergent
multipole moments. Such multipole moments have broken space-inversion and
time-reversal symmetries, and can therefore exhibit linear magnetoelectric (ME)
activity. Three types of such multipole moments are known: toroidal, monopole,
and quadrupole moments. So far, however, the ME-activity of these multipole
moments has only been established experimentally for the toroidal moment. Here,
we propose a magnetic square cupola cluster, in which four corner-sharing
square-coordinated metal-ligand fragments form a noncoplanar buckled structure,
as a promising structural unit that carries an ME-active multipole moment. We
substantiate this idea by observing clear magnetodielectric signals associated
with an antiferroic ME-active magnetic quadrupole order in the real material
Ba(TiO)Cu$_4$(PO$_4$)$_4$. The present result serves as a useful guide for
exploring and designing new ME-active materials based on vortex-like spin
arrangements.


title: Model Driven Web Application Development With Agile Practices

abstract:
  Model driven development is an effective method due to its benefits such as
code transformation, increasing productivity and reducing human based error
possibilities. Meanwhile, agile software development increases the software
flexibility and customer satisfaction by using iterative method. Can these two
development approaches be combined to develop web applications efficiently?
What are the challenges and what are the benefits of this approach? In this
paper, we answer these two crucial problems; combining model driven development
and agile software development results in not only fast development and
easiness of the user interface design but also efficient job tracking. We also
defined an agile model based approach for web applications whose implementation
study has been carried out to support the answers we gave these two crucial
problems.


title: Recovering the fundamental plane of galaxies by $f(R)$ gravity

abstract:
  The fundamental plane (FP) of galaxies can be recovered in the framework of
$f(R)$ gravity avoiding the issues related to dark matter to fit the
observations. In particular, the power-law version $f(R)\propto R^n$, resulting
from the existence of Noether symmetries for $f(R)$, is sufficient to implement
the approach. In fact, relations between the FP parameters and the corrected
Newtonian potential, coming from $R^n$, can be found and justified from a
physical point of view. Specifically, we analyze the velocity distribution of
elliptical galaxies and obtain that $r_c$, the scale-length depending on the
gravitational system properties, is proportional to $r_e$, the galaxy effective
radius. This fact points out that the gravitational corrections induced by
$f(R)$ can lead photometry and dynamics of the system. Furthermore, the main
byproduct of such an approach is that gravity could work in different ways
depending on the scales of self-gravitating systems.


title: String Cadences

abstract:
  We say a string has a cadence if a certain character is repeated at regular
intervals, possibly with intervening occurrences of that character. We call the
cadence anchored if the first interval must be the same length as the others.
We give a sub-quadratic algorithm for determining whether a string has any
cadence consisting of at least three occurrences of a character, and a nearly
linear algorithm for finding all anchored cadences.


title: Across the deconfinement

abstract:
  The deconfinement transition at vanishing chemical potential can be reliably
studied by lattice simulations and its general features are by now well known.
On the contrary, what happens at finite density is still largely unknown and we
will review the results obtained in the last year regarding the dependence, for
small density, of the (pseudo)critical temperature on the baryonic chemical
potential.


title:
Sectional and intermediate Ricci curvature lower bounds via Optimal
  Transport

abstract:
  The goal of the paper is to give an optimal transport characterization of
sectional curvature lower (and upper) bounds for smooth $n$-dimensional
Riemannian manifolds. More generally we characterize, via optimal transport,
lower bounds on the so called $p$-Ricci curvature which corresponds to taking
the trace of the Riemann curvature tensor on $p$-dimensional planes, $1\leq
p\leq n$. Such characterization roughly consists on a convexity condition of
the $p$-Renyi entropy along $L^{2}$-Wasserstein geodesics, where the role of
reference measure is played by the $p$-dimensional Hausdorff measure. As
application we establish a new Brunn-Minkowski type inequality involving
$p$-dimensional submanifolds and the $p$-dimensional Hausdorff measure.


title: On the distribution of maximal gaps between primes in residue classes

abstract:
  Let $q>r\ge1$ be coprime positive integers. We empirically study the maximal
gaps $G_{q,r}(x)$ between primes $p=qn+r\le x$, $n\in{\mathbb N}$. Extensive
computations suggest that almost always $G_{q,r}(x)<\varphi(q)\log^2x$. More
precisely, the vast majority of maximal gaps are near a trend curve $T$
predicted using a generalization of Wolf's conjecture: $$G_{q,r}(x) ~\sim~
T(q,x)={\varphi(q)x\over{\rm li}(x)} \Big(2\log{{\rm li}(x)\over\varphi(q)} -
\log x + b\Big),$$ where $b = b(q,x) = O_q(1)$. The distribution of properly
rescaled maximal gaps $G_{q,r}(x)$ is close to the Gumbel extreme value
distribution. However, the question whether there exists a limiting
distribution of $G_{q,r}(x)$ is open. We discuss possible generalizations of
Cramer's, Shanks, and Firoozbakht's conjectures to primes in residue classes.


title:
Proposal for Automatic License and Number Plate Recognition System for
  Vehicle Identification

abstract:
  In this paper, we propose an automatic and mechanized license and number
plate recognition (LNPR) system which can extract the license plate number of
the vehicles passing through a given location using image processing
algorithms. No additional devices such as GPS or radio frequency identification
(RFID) need to be installed for implementing the proposed system. Using special
cameras, the system takes pictures from each passing vehicle and forwards the
image to the computer for being processed by the LPR software. Plate
recognition software uses different algorithms such as localization,
orientation, normalization, segmentation and finally optical character
recognition (OCR). The resulting data is applied to compare with the records on
a database. Experimental results reveal that the presented system successfully
detects and recognizes the vehicle number plate on real images. This system can
also be used for security and traffic control.


title:
From phonemes to images: levels of representation in a recurrent neural
  model of visually-grounded language learning

abstract:
  We present a model of visually-grounded language learning based on stacked
gated recurrent neural networks which learns to predict visual features given
an image description in the form of a sequence of phonemes. The learning task
resembles that faced by human language learners who need to discover both
structure and meaning from noisy and ambiguous data across modalities. We show
that our model indeed learns to predict features of the visual context given
phonetically transcribed image descriptions, and show that it represents
linguistic information in a hierarchy of levels: lower layers in the stack are
comparatively more sensitive to form, whereas higher layers are more sensitive
to meaning.


title:
Efficient molecular dynamics simulations with many-body potentials on
  graphics processing units

abstract:
  Graphics processing units have been extensively used to accelerate classical
molecular dynamics simulations. However, there is much less progress on the
acceleration of force evaluations for many-body potentials compared to pairwise
ones. In the conventional force evaluation algorithm for many-body potentials,
the force, virial stress, and heat current for a given atom are accumulated
within different loops, which could result in write conflict between different
threads in a CUDA kernel. In this work, we provide a new force evaluation
algorithm, which is based on an explicit pairwise force expression for
many-body potentials derived recently [Phys. Rev. B 92 (2015) 094301]. In our
algorithm, the force, virial stress, and heat current for a given atom can be
accumulated within a single thread and is free of write conflicts. We discuss
the formulations and algorithms and evaluate their performance. A new
open-source code, GPUMD, is developed based on the proposed formulations. For
the Tersoff many-body potential, the double precision performance of GPUMD
using a Tesla K40 card is equivalent to that of the LAMMPS (Large-scale
Atomic/Molecular Massively Parallel Simulator) molecular dynamics code running
with about 100 CPU cores (Intel Xeon CPU X5670 @ 2.93 GHz).


title: Attention and Anticipation in Fast Visual-Inertial Navigation

abstract:
  We study a Visual-Inertial Navigation (VIN) problem in which a robot needs to
estimate its state using an on-board camera and an inertial sensor, without any
prior knowledge of the external environment. We consider the case in which the
robot can allocate limited resources to VIN, due to tight computational
constraints. Therefore, we answer the following question: under limited
resources, what are the most relevant visual cues to maximize the performance
of visual-inertial navigation? Our approach has four key ingredients. First, it
is task-driven, in that the selection of the visual cues is guided by a metric
quantifying the VIN performance. Second, it exploits the notion of
anticipation, since it uses a simplified model for forward-simulation of robot
dynamics, predicting the utility of a set of visual cues over a future time
horizon. Third, it is efficient and easy to implement, since it leads to a
greedy algorithm for the selection of the most relevant visual cues. Fourth, it
provides formal performance guarantees: we leverage submodularity to prove that
the greedy selection cannot be far from the optimal (combinatorial) selection.
Simulations and real experiments on agile drones show that our approach ensures
state-of-the-art VIN performance while maintaining a lean processing time. In
the easy scenarios, our approach outperforms appearance-based feature selection
in terms of localization errors. In the most challenging scenarios, it enables
accurate visual-inertial navigation while appearance-based feature selection
fails to track robot's motion during aggressive maneuvers.


title: Pure E and B polarization maps via Wiener filtering

abstract:
  In order to draw scientific conclusions from observations of cosmic microwave
background (CMB) polarization, it is necessary to separate the contributions of
the E and B components of the data. For data with incomplete sky coverage,
there are ambiguous modes, which can be sourced by either E or B signals.
Techniques exist for producing "pure" E and B maps, which are guaranteed to be
free of cross-contamination, although the standard method, which involves
constructing an eigenbasis, has a high computational cost. We show that such
pure maps can be thought of as resulting from the application of a Wiener
filter to the data. This perspective leads to far more efficient methods of
producing pure maps. Moreover, by expressing the idea of purification in the
general framework of Wiener filtering (i.e., maximization of a posterior
probability), it leads to a variety of generalizations of the notion of pure E
and B maps, e.g., accounting for noise or other contaminants in the data as
well as correlations with temperature anisotropy.


title: Notions of Anonymous Existence in Martin-L\"of Type Theory

abstract:
  As the groupoid model of Hofmann and Streicher proves, identity proofs in
intensional Martin-L\"of type theory cannot generally be shown to be unique.
Inspired by a theorem by Hedberg, we give some simple characterizations of
types that do have unique identity proofs. A key ingredient in these
constructions are weakly constant endofunctions on identity types. We study
such endofunctions on arbitrary types and show that they always factor through
a propositional type, the truncated or squashed domain. Such a factorization is
impossible for weakly constant functions in general (a result by Shulman), but
we present several non-trivial cases in which it can be done. Based on these
results, we define a new notion of anonymous existence in type theory and
compare different forms of existence carefully. In addition, we show possibly
surprising consequences of the judgmental computation rule of the truncation,
in particular in the context of homotopy type theory. All the results have been
formalized and verified in the dependently typed programming language Agda.


title:
Techniques And Results For The Calibration Of The MST Prototype For The
  Cherenkov Telescope Array

abstract:
  The next generation instrument for ground-based gamma-ray astronomy will be
the Cherenkov Telescope Array (CTA), consisting of approximately 100 telescopes
in three sizes, built on two sites with one each in the Northern and Southern
Hemi- spheres. Up to 40 of these will be Medium Size Telescopes (MSTs) which
will dominate sensitivity in the core energy range. Since 2012, a full size
mechanical prototype for the modified 12 m Davies-Cotton design MST has been in
operation in Berlin. This doc- ument describes the techniques which have been
implemented to calibrate and optimise the mechanical and optical performance of
the prototype, and gives the results of over three years of observations and
measurements. Pointing calibration techniques will be discussed, along with the
development of a bending model, and calibration of the CCD cameras used for
pointing measurements. Additionally alignment of mirror segments using the
Bokeh method is shown.


title:
Near Optimal Adaptive Shortest Path Routing with Stochastic Links States
  under Adversarial Attack

abstract:
  We consider the shortest path routing (SPR) of a network with stochastically
time varying link metrics under potential adversarial attacks. Due to potential
denial of service attacks, the distributions of link states could be stochastic
(benign) or adversarial at different temporal and spatial locations. Without
any \emph{a priori}, designing an adaptive SPR protocol to cope with all
possible situations in practice optimally is a very challenging issue. In this
paper, we present the first solution by formulating it as a multi-armed bandit
(MAB) problem. By introducing a novel control parameter into the exploration
phase for each link, a martingale inequality is applied in the our
combinatorial adversarial MAB framework. As such, our proposed algorithms could
automatically detect features of the environment within a unified framework and
find the optimal SPR strategies with almost optimal learning performance in all
possible cases over time. Moreover, we study important issues related to the
practical implementation, such as decoupling route selection with multi-path
route probing, cooperative learning among multiple sources, the "cold-start"
issue and delayed feedback of our algorithm. Nonetheless, the proposed SPR
algorithms can be implemented with low complexity and they are proved to scale
very well with the network size. Comparing to existing approaches in a typical
network scenario under jamming attacks, our algorithm has a 65.3\% improvement
of network delay given a learning period and a 81.5\% improvement of learning
duration under a specified network delay.


title:
Survey on the Use of Typological Information in Natural Language
  Processing

abstract:
  In recent years linguistic typology, which classifies the world's languages
according to their functional and structural properties, has been widely used
to support multilingual NLP. While the growing importance of typological
information in supporting multilingual tasks has been recognised, no systematic
survey of existing typological resources and their use in NLP has been
published. This paper provides such a survey as well as discussion which we
hope will both inform and inspire future work in the area.


title:
Small $x$ gluon shadowing from LHC data on coherent $\mathrm{J/}\psi$
  photoproduction

abstract:
  The cross section for coherent $\mathrm{J/}\psi$ photoproduction in Pb-Pb
collisions is the sum of two contributions, one from low-, the other from
high-energy photon-nucleus interactions. A novel method to disentangle both
contributions allowing one to extract the coherent photo-nuclear cross section
for coherent $\mathrm{J/}\psi$ production, $\sigma_{\gamma \rm Pb}$, is
presented. The utility of the method is demonstrated using measurements from
peripheral and ultra-peripheral Pb-Pb collisions at the LHC. Applying the
proposed method to the available data it is possible to obtain $\sigma_{\gamma
\rm Pb}$ up to a photon-lead centre-of-mass energy of 470 GeV, which
corresponds to $x$ of 4.4x10$^{-5}$. To illustrate a possible use of the
extracted photo-nuclear cross sections, the corresponding nuclear suppression
factors are computed and they are compared to predictions of gluon shadowing
calculated in the leading-twist approximation approach.


title:
A general relativistic signature in the galaxy bispectrum: the local
  effects of observing on the lightcone

abstract:
  Next-generation galaxy surveys will increasingly rely on the galaxy
bispectrum to improve cosmological constraints, especially on primordial
non-Gaussianity. A key theoretical requirement that remains to be developed is
the analysis of general relativistic effects on the bispectrum, which arise
from observing galaxies on the past lightcone, {as well as from relativistic
corrections to the dynamics}. {As an initial step towards a fully relativistic
analysis of the galaxy bispectrum, we compute for the first time the local
relativistic lightcone effects on the bispectrum,} which come from Doppler and
gravitational potential contributions. For the galaxy bispectrum, the problem
is much more complex than for the power spectrum, since we need the lightcone
corrections at second order. Mode-coupling contributions at second order mean
that relativistic corrections can be non-negligible at smaller scales than in
the case of the power spectrum. In a primordial Gaussian universe, we show that
the local lightcone corrections for squeezed shapes at $z\sim1$ mean that the
bispectrum can differ from the Newtonian prediction by $\gtrsim 10\%$ when the
short modes are $k\lesssim (50\,{\rm Mpc})^{-1}$. These relativistic projection
effects, if ignored in the analysis of observations, could be mistaken for
primordial non-Gaussianity. For upcoming surveys which probe equality scales
and beyond, {all relativistic lightcone effects and relativistic dynamical
corrections should be included} for an accurate measurement of primordial
non-Gaussianity.


title:
Topological superfluidity of lattice fermions inside a Bose-Einstein
  condensate

abstract:
  We calculate the phase diagram of identical fermions in a 2-dimensional (2D)
lattice immersed in a 3D Bose-Einstein condensate (BEC). The fermions exchange
density fluctuations in the BEC, which gives rise to an attractive induced
interaction. The resulting zero temperature phase diagram exhibits topological
$p_x+ip_y$ superfluid phases as well as a phase separation region. We show how
to use the flexibility of the Bose-Fermi mixture to tune the induced
interaction, so that it maximises the pairing between nearest neighbour sites,
whereas phase separation originating from long range interactions is
suppressed. Finally, we calculate the Berezinskii-Kosterlitz-Thouless (BKT)
critical temperature of the topological superfluid in the lattice and discuss
experimental realisations.


title: Heegaard Floer invariants in codimension one

abstract:
  Using Heegaard Floer homology, we construct a numerical invariant for any
smooth, oriented $4$-manifold $X$ with the homology of $S^1 \times S^3$.
Specifically, we show that for any smoothly embedded $3$-manifold $Y$
representing a generator of $H_3(X)$, a suitable version of the Heegaard Floer
$d$ invariant of $Y$, defined using twisted coefficients, is a diffeomorphism
invariant of $X$. We show how this invariant can be used to obstruct embeddings
of certain types of $3$-manifolds, including those obtained as a connected sum
of a rational homology $3$-sphere and any number of copies of $S^1 \times S^2$.
We also give similar obstructions to embeddings in certain open $4$-manifolds,
including exotic $\mathbb{R}^4$s.


title: Filtration Relative, l'Id\'eal de Bernstein et ses pentes

abstract:
  Let $ f_i: X \rightarrow {\bf C}$, for $i$ integer between $ 1$ and $ p $, be
analytic functions defined on a complex analytic variety $X$. Let us consider $
{\cal D}_X $ the ring of linear differential operators and $ {\cal D}_X [s_1,
\ldots, s_p] = {\bf C}_X [s_1, \ldots, s_p] \otimes_ {\bf C} {\cal D}_X$. Let $
m $ be a section of a holonomic $ {\cal D}_X $-Module. We denote $ {\cal B}(m,
x_0, f_1, \ldots, f_p) $ the ideal of $ { \bf C} [s_1, \ldots, s_p] $
constituted by the polynomials $ b $ satisfying in the neighborhood of $ x_0
\in X$ : $$ B (s_1, \ldots, s_p) m f_1^{ s_1} \ldots f_p ^{s_p} \in {\cal D}_X
[s_1, \ldots, s_p] \, m f_1^{s_1 + 1} \ldots f_p^{s_p + 1} \; . $$ This ideal
is called Bernstein's ideal. C. Sabbah shows the existence for every $ x_0 \in
X $ of a finite set $ {\cal H} $ of linear forms with coefficients in $ {\bf N}
$, such that: $$ \prod_{H \in {\cal H}} \prod_{i \in I_{\cal H}} (H (s_1,
\ldots, s_p) + \alpha_{H , i}) \in {\cal B} (m, x_0, f_1, \ldots, f_p) \; , $$
where $\alpha_{H,i} $ are complex numbers. The purpose of this article is to
show in particular the existence of a minimal set $ {\cal H} $. In addition,
when $ m $ is a section of a holonomic regular ${\cal D}_X$-Module, we will
precise geometrically this set from the characteristic variety of ${\cal
D}_X$-Module generated by $m$. We introduce and study especially the relative
characteristic variety of the $ {\cal D}_X [s_1, \ldots, s_p] $ - Modules
related to our problem. This allows to specify the structure of the Bernstein's
ideals.


title: Nonlinear Quantum Optics in Optomechanical Nanoscale Waveguides

abstract:
  We explore the possibility of achieving a significant nonlinear phase shift
among photons propagating in nanoscale waveguides exploiting interactions among
photons that are mediated by vibrational modes and induced through Stimulated
Brillouin Scattering (SBS). We introduce a configuration that allows slowing
down the photons by several orders of magnitude via SBS involving sound waves
and two pump fields. We extract the conditions for maintaining vanishing
amplitude gain or loss for slowly propagating photons while keeping the
influence of thermal phonons to the minimum. The nonlinear phase among two
counter-propagating photons can be used to realize a deterministic phase gate.


title: L'id\'eal de Bernstein d'un arrangement libre d'hyperplans lin\'eaires

abstract:
  Let $ V $ a vector space of dimension $n$. A family $ \{H_1, \ldots, H_p \} $
of vectorial hyperplans $V$ defines an arrangement $ {\cal A} $ of $ V $. For $
i \in \{ 1, \ldots, p \} $, let $ l_i $ be a linear form on $V$ with $H_i$ as
kernel. We denote by $A_V ({\bf C}) $, the Weyl algebra of algebraic
differential operators on $V$. Following J. Bernstein, the ideal constituted by
polynomials $ b \in {\bf C} [s_1, \ldots, s_p] $ such that : $$ \; \; b (s_1,
\ldots, s_p) \, l_1^{s_1} \ldots l_p^{s_p} \in A_n ({\bf C}) [s_1, \ldots, s_p]
\, l_1^ {s_1 + 1} \ldots l_p^{s_p + 1} \; , $$ is not reduced to zero. This
ideal does not depend on the choice of linear forms $ l_i $. The goal of this
article is to determine this ideal when $ {\cal A} $ is a free arrangement
constituted by linear hyperplans within the meaning of K. Saito.


title: Id\'eal de Bernstein d'un arrangement central g\'en\'erique d'hyperplans

abstract:
  Let $ V $ a vector space of dimension $n$. A $V$ family $ \{H_1, \ldots, H_p
\} $ of vectorial hyperplanes being distinct two by two defines an arrangement
$ {\cal A}_p = {\cal A} ( H_1, \ldots ,H_p ) $ of $ V $. For $ i \in \{ 1,
\ldots, p \} $, let $ l_i $ be a linear form on $V$ with $H_i$ as kernel. This
arrangement is generic if the intersection of every sub-family of $n$
hyperplanes of the arranfement is reduced to zero. Let $A_V ({\bf C}) $, be the
Weyl algebra of algebraic differential operators with coefficients in the
symetric algebra denoted $S$ of the dual of $V$. Following J. Bernstein, the
ideal constituted by polynomials $ b \in {\bf C} [s_1, \ldots, s_p] $ such that
: $$ \; \; b (s_1, \ldots, s_p) \, l_1^{s_1} \ldots l_p^{s_p} \in A_V ({\bf C})
[s_1, \ldots, s_p] \, l_1^ {s_1 + 1} \ldots l_p^{s_p + 1} $$ is not reduced to
zero. This ideal does not depend on the choice of linear forms $l_i $ which
define the hypersurfaces $H_i$. The goal of this article is to precise this
ideal.


title:
Chaotic Behavior of Stiff ODEs and Their Derivatives: An Illustrative
  Example

abstract:
  In the following, an illustrative example concerning difficulties in
differentiating stiff ODEs is presented. In the given example, the solution of
a completely deterministic system becomes chaotic due to computational noise
introduced by the numerical algorithm.


title:
On time dependent Schr{\"o}dinger equations: global well-posedness and
  growth of Sobolev norms

abstract:
  In this paper we consider time dependent Schr{\"o}dinger linear PDEs of the
form i$\partial$t$\psi$ = L(t)$\psi$, where L(t) is a continuous family of
self-adjoint operators. We give conditions for well-posedness and polynomial
growth for the evolution in abstract Sobolev spaces. If L(t) = H + V (t) where
V (t) is a perturbation smooth in time and H is a self-adjoint positive
operator whose spectrum can be enclosed in spectral clusters whose distance is
increasing, we prove that the Sobolev norms of the solution grow at most as t
$\epsilon$ when t $\rightarrow$ $\infty$, for any $\epsilon$ \textgreater{} 0.
If V (t) is analytic in time we improve the bound to (log t) $\gamma$ , for
some $\gamma$ \textgreater{} 0. The proof follows the strategy, due to Howland,
Joye and Nenciu, of the adiabatic approximation of the flow. We recover most of
known results and obtain new estimates for several models including 1-degree of
freedom Schr{\"o}dinger operators on R and Schr{\"o}dinger operators on Zoll
manifolds.