title: Pattern formation of frictional fingers in a gravitational potential

abstract:
  Aligned finger structures, with a characteristic width, emerges during the
slow drainage of a liquid/granular mixture in a tilted Hele-Shaw cell. A
transition from vertical to horizontal alignment of the finger structures is
observed as the tilting angle and the granular density are varied. An
analytical model is presented, demonstrating that the alignment properties is
the result of the competition between fluctuating granular stresses and the
hydrostatic pressure. The dynamics is reproduced in simulations. We also show
how the system explains patterns made during dyke formations.


title: Singular Fr\'egier Conics in Non-Euclidean Geometry

abstract:
  The hypotenuses of all right triangles inscribed into a fixed conic $C$ with
fixed right-angle vertex $p$ are incident with the Fr\'egier point $f$ to $p$
and $C$. As $p$ varies on the conic, the locus of the Fr\'egier point is, in
general, a conic as well. We study conics $C$ whose Fr\'egier locus is singular
in Euclidean, elliptic and hyperbolic geometry. The richest variety of conics
with this property is obtained in hyperbolic plane while in elliptic geometry
only three families of conics have a singular Fr\'egier locus.


title: Black holes in a cubic Galileon universe

abstract:
  We find and study the properties of black hole solutions for a subclass of
Horndeski theory including the cubic Galileon term. The theory under study has
shift symmetry but not reflection symmetry for the scalar field. The Galileon
is assumed to have linear time dependence characterized by a velocity
parameter. We give analytic 3-dimensional solutions that are akin to the BTZ
solutions but with a non-trivial scalar field that modifies the effective
cosmological constant. We then study the 4-dimensional asymptotically flat and
de Sitter solutions. The latter present three different branches according to
their effective cosmological constant. For two of these branches, we find
families of black hole solutions, parametrized by the velocity of the scalar
field. These spherically symmetric solutions, obtained numerically, are
different from GR solutions close to the black hole event horizon, while they
have the same de-Sitter asymptotic behavior. The velocity parameter represents
black hole primary hair.


title:
Bayesian Principal Component Regression model with spatial effects for
  forest inventory under small field sample size

abstract:
  Remote sensing observations are extensively used for analysis of
environmental variables. These variables often exhibit spatial correlation,
which has to be accounted for in the calibration models used in predictions,
either by direct modelling of the dependencies or by allowing for spatially
correlated stochastic effects. Another feature in many remote sensing
instruments is that the derived predictor variables are highly correlated,
which can lead to unnecessary model over-training and at worst, singularities
in the estimates. Both of these affect the prediction accuracy, especially when
the training set for model calibration is small. To overcome these modelling
challenges, we present a general model calibration procedure for remotely
sensed data and apply it to airborne laser scanning data for forest inventory.
We use a linear regression model that accounts for multicollinearity in the
predictors by principal components and Bayesian regularization. It has a
spatial random effect component for the spatial correlations that are not
explained by a simple linear model. An efficient Markov chain Monte Carlo
sampling scheme is used to account for the uncertainty in all the model
parameters. We tested the proposed model against several alternatives and it
outperformed the other linear calibration models, especially when there were
spatial effects, multicollinearity and the training set size was small.


title: The subdivision of large simplicial cones in Normaliz

abstract:
  Normaliz is an open-source software for the computation of lattice points in
rational polyhedra, or, in a different language, the solutions of linear
diophantine systems. The two main computational goals are (i) finding a system
of generators of the set of lattice points and (ii) counting elements
degree-wise in a generating function, the Hilbert Series. In the homogeneous
case, in which the polyhedron is a cone, the set of generators is the Hilbert
basis of the intersection of the cone and the lattice, an affine monoid.
  We will present some improvements to the Normaliz algorithm by subdividing
simplicial cones with huge volumes. In the first approach the subdivision
points are found by integer programming techniques. For this purpose we
interface to the integer programming solver SCIP to our software. In the second
approach we try to find good subdivision points in an approximating overcone
that is faster to compute.


title: Spin Hall Magnetoresistance in a Canted Ferrimagnet

abstract:
  We study the spin Hall magnetoresistance effect in ferrimagnet/normal metal
bilayers, comparing the response in collinear and canted magnetic phases. In
the collinear magnetic phase, in which the sublattice magnetic moments are all
aligned along the same axis, we observe the conventional spin Hall
magnetoresistance. In contrast, in the canted phase, the magnetoresistance
changes sign. Using atomistic spin model calculations of the magnetic
configuration, we show that the electric transport for the different magnetic
phases can be rationalized considering the individual sublattice moment
orientations. This enables a magneto-transport based investigation of
non-collinear magnetic textures.


title: 24-Hour Relativistic Bit Commitment

abstract:
  Bit commitment is a fundamental cryptographic primitive in which a party
wishes to commit a secret bit to another party. Perfect security between
mistrustful parties is unfortunately impossible to achieve through the
asynchronous exchange of classical and quantum messages. Perfect security can
nonetheless be achieved if each party splits into two agents exchanging
classical information at times and locations satisfying strict relativistic
constraints. A relativistic multi-round protocol to achieve this was previously
proposed and used to implement a 2~millisecond commitment time. Much longer
durations were initially thought to be insecure, but recent theoretical
progress showed that this is not so. In this letter, we report on the
implementation of a 24-hour bit commitment based on timed high-speed optical
communication and fast data processing only, with all agents located within the
city of Geneva. This duration is more than six orders of magnitude longer than
before, and we argue that it could be extended to one year and allow much more
flexibility on the locations of the agents. Our implementation offers a
practical and viable solution for use in applications such as digital
signatures, secure voting and honesty-preserving auctions.


title:
Spectral/hp Hull: A Degree of Freedom Reducing Discontinuous Spectral
  Element Method for Conservation Laws with Application to Compressible Fluid
  Flow

abstract:
  In conventional spectral/finite element methods, the
triangulation/quadrilateralization of the domain produces many interior edges
which require additional DOF. What if we could directly use the original hull
without going to triangulation/quadrilateralization? There are three major
difficulties with this type of approach that are addressed: 1- How can a convex
hull tessellation be obtained for complex geometries encountered in practical
engineering applications? 2- How can basis functions and quadrature points be
defined on these hulls? 3- How can this type of grid and corresponding basis
functions be used in practice to yield accurate discretization of nonlinear
conservation laws? Geometrical approaches to tackle the first challenge are
discussed . To solve the second challenge, for the first time in the
literature, a closed form relation is proposed to approximate Fekete points (a
Nondeterministic Polynomial (NP) problem) on a general convex/concave
polyhedral. The approximate points are used to generate basis functions using
the SVD of the Vandermonde matrix. The type of basis functions derived include
Lagrange basis, orthogonal and orthonormal hull basis and radial basis. It is
shown that the hull basis is the best choice to enforce minimum DOF while
maintaining a small Lebesgue constant when very high p-refinement is done. The
proposed hull basis is rigorously proven to achieve arbitrary order of accuracy
by satisfying Weierstrass approximation theorem in $\mathbb{R}^d$. The third
challenge is met using a standard Discontinuous Galerkin (DG) and Discontinuous
Least-Squares (DLS) spectral hull formulations. The accuracy and stability of
the formulation is demonstrated for the linearized acoustics and
two-dimensional compressible Euler equations on some benchmark problems
including a cylinder, airfoil, vortex convection and compressible vortex
shedding from a triangle.


title: Quantum algorithm for association rules mining

abstract:
  Association rules mining (ARM) is one of the most important problems in
knowledge discovery and data mining. Given a transaction database that has a
large number of transactions and items, the task of ARM is to acquire
consumption habits of customers by discovering the relationships between
itemsets (sets of items). In this paper, we address ARM in the quantum settings
and propose a quantum algorithm for the key part of ARM, finding out frequent
itemsets from the candidate itemsets and acquiring their supports.
Specifically, for the case in which there are $M_f^{(k)}$ frequent $k$-itemsets
in the $M_c^{(k)}$ candidate $k$-itemsets ($M_f^{(k)} \leq M_c^{(k)}$), our
algorithm can efficiently mine these frequent $k$-itemsets and estimate their
supports by using parallel amplitude estimation and amplitude amplification
with complexity $\mathcal{O}(\frac{k\sqrt{M_c^{(k)}M_f^{(k)}}}{\epsilon})$,
where $\epsilon$ is the error for estimating the supports. Compared with the
classical counterpart, classical sampling-based algorithm, whose complexity is
$\mathcal{O}(\frac{kM_c^{(k)}}{\epsilon^2})$, our quantum algorithm
quadratically improves the dependence on both $\epsilon$ and $M_c^{(k)}$ in the
best case when $M_f^{(k)}\ll M_c^{(k)}$ and on $\epsilon$ alone in the worst
case when $M_f^{(k)}\approx M_c^{(k)}$.


title:
Global existence of weak solutions of a model for electrolyte solutions
  - Part 2: Multicomponent case

abstract:
  This paper analytically investigates the Darcy-Poisson-Nernst-Planck system.
This system is a mathematical model for electrolyte solutions. In this paper,
we consider electrolyte solutions, which consist of a neutral fluid and
multiple suspended charged chemical species with arbitrary valencies. We prove
global existence and uniqueness of weak solutions in two space dimensions.


title:
Infrared properties of heavy-fermions: evolution from weak to strong
  hybridizations

abstract:
  In this article, we review the charge excitations of heavy fermion compounds
probed by infrared spectroscopy. The article is not meant to be a comprehensive
survey of experimental investigations. Rather it focuses on the dependence of
charge excitations on the hybridization strength. In this context, the infrared
properties of the Ce$_m$M$_n$In$_{3m+2n}$ family are discussed in detail since
the hybridization strengths differ dramatically in different members despite
their similar lattice structures. Investigations on some mixed valent compounds
are also presented aiming to elucidate the generic trend on the evolution. In
particular, we address the scaling between hybridization energy gap
$\Delta_{dir}$ and the hybridization strength $\tilde{V}$($\propto\sqrt{WT_K}$)
in a wide range of heavy fermions compounds which demonstrates that the
periodic Anderson model can generally and quantitatively describe the
low-energy charge excitations.


title: Completion and torsion over commutative DG rings

abstract:
  Let $\operatorname{CDG}_{cont}$ be the category whose objects are pairs
$(A,\bar{\mathfrak{a}})$, where $A$ is a commutative DG-algebra and
$\bar{\mathfrak{a}}\subseteq \mathrm{H}^0(A)$ is a finitely generated ideal,
and whose morphisms $f:(A,\bar{\mathfrak{a}}) \to (B,\bar{\mathfrak{b}})$ are
morphisms of DG-algebras $A \to B$, such that
$(\mathrm{H}^0(f)(\bar{\mathfrak{a}})) \subseteq \bar{\mathfrak{b}}$. Letting
$\mathrm{Ho}(\operatorname{CDG}_{cont})$ be its homotopy category, obtained by
inverting adic quasi-isomorphisms, we construct a functor
$\mathrm{L}\Lambda:\mathrm{Ho}(\operatorname{CDG}_{cont}) \to
\mathrm{Ho}(\operatorname{CDG}_{cont})$ which takes a pair
$(A,\bar{\mathfrak{a}})$ into its non-abelian derived $\bar{\mathfrak{a}}$-adic
completion. We show that this operation has, in a derived sense, the usual
properties of adic completion of commutative rings, and that if $A =
\mathrm{H}^0(A)$ is an ordinary noetherian ring, this operation coincides with
ordinary adic completion. As an application, following a question of Buchweitz
and Flenner, we show that if $\Bbbk$ is a commutative ring, and $A$ is a
commutative $\Bbbk$-algebra which is $\mathfrak{a}$-adically complete with
respect to a finitely generated ideal $\mathfrak{a}\subseteq A$, then the
derived Hochschild cohomology modules
$\operatorname{Ext}^n_{A\otimes^{\mathrm{L}}_{\Bbbk} A} (A,A)$ and the derived
complete Hochschild cohomology modules
$\operatorname{Ext}^n_{A\widehat{\otimes}^{\mathrm{L}}_{\Bbbk} A} (A,A)$
coincide, without assuming any finiteness or noetherian conditions on $\Bbbk,
A$ or on the map $\Bbbk \to A$.


title:
Roles of heating and helicity in ultrafast all-optical magnetization
  switching in TbFeCo

abstract:
  Using time-resolved magneto-optical Kerr effect (TR-MOKE) method,
helicity-dependent all-optical magnetization switching (HD-AOS) is observed in
ferrimagnetic TbFeCo films. The thermal effect and opto-magneto effects are
separately justified after single circularly polarized laser pulse. The
integral evolution of this ultrafast switching is characterized on different
time scales and the defined magnetization reversal time of 460 fs is the
fastest ever observed. Combining the heat effect and inverse Faraday effect
(IFE), micromagnetic simulations based on a single macro-spin model are
performed that reproduce HD-AOS following a linear reversal mechanism.


title:
Commutators of multilinear Calder\'on-Zygmund operators with kernels of
  Dini's type and applications

abstract:
  Let $T$ be a multilinear Calder\'on-Zygmund operator of type $\omega$ with
$\omega(t)$ being nondecreasing and satisfying a kind of Dini's type condition.
Let $T_{\Pi\vec{b}}$ be the iterated commutators of $T$ with $BMO$ functions.
The weighted strong and weak $L(\log{L})$-type endpoint estimates for
$T_{\Pi\vec{b}}$ with multiple weights are established. Some boundedness
properties on weighted variable exponent Lebesgue spaces are also obtained.
  As applications, multiple weighted estimates for iterated commutators of
paraproducts and bilinear pseudo-differential operators with mild regularity
are given.


title:
The effective method to calculate eigenvalues of Chandrasekhar-Page
  angular equations

abstract:
  An effective, reliable and time saving numerical method with using of the
Pruefer transformation is proposed to calculate eigenvalues of
Chandrasekhar-Page angular equations.


title: Thermally Activated Fracture of Porous Media

abstract:
  The lifetime of a porous media, submitted to a constant subcritical stress,
is studied by means of a numerical model. This model is based on a spring
network where the porosity is represented by missing springs. The dynamics is
produced adding thermal fluctuations in spring forces. The lifetime predicted
by the models are compared to experimental data of delayed fracture of porous
media submitted to three-point flexion fracture experiments.


title: Superballistic wavepacket spreading in double kicked rotors

abstract:
  We investigate possible ways in which a quantum wavepacket spreads. We show
that in a general class of double kicked rotor systems, a wavepacket may
undergo superballistic spreading; i.e., its variance increases as the cubic of
time. The conditions for the observed superballistic spreading and two related
characteristic time scales are studied. Our results suggest that the symmetry
of the studied model and whether it is a Kolmogorov-Arnold-Moser system are
crucial to its wavepacket spreading behavior. Our study also sheds new light on
the exponential wavepacket spreading phenomenon previously observed in the
double kicked rotor systems.


title: Searching for hidden-charm baryonium signals in QCD sum rules

abstract:
  We give an explicit QCD sum rule investigation to hidden-charm baryonium
states with the quark content $u\bar u d\bar d c\bar c$, spin $J=0/1/2/3$, and
of both positive and negative parities. We systematically construct the
relevant local hidden-charm baryonium interpolating currents, which can
actually couple to various structures, including hidden-charm baryonium states,
charmonium states plus two pions, and hidden-charm tetraquark states plus one
pion, etc. We do not know which structure these currents couple to at the
beginning, but after sum rule analyses we can obtain some information. We find
some of them can couple to hidden-charm baryonium states, using which we
evaluate the masses of the lowest-lying hidden-charm baryonium states with
quantum numbers $J^P=2^-/3^-/0^+/1^+/2^+$ to be around 5.0 GeV. We suggest to
search for hidden-charm baryonium states, especially the one of $J=3^-$, in the
$D$-wave $J/\psi \pi \pi$ and $P$-wave $J/\psi \rho$ and $J/\psi \omega$
channels in this energy region.


title:
Subcritical convection of liquid metals in a rotating sphere using a
  quasi-geostrophic model

abstract:
  We study nonlinear convection in a rapidly rotating sphere with internal
heating for values of the Prandtl number relevant for liquid metals
($Pr\in[10^{-2},10^{-1}]$). We use a numerical model based on the
quasi-geostrophic approximation, in which variations of the axial vorticity
along the rotation axis are neglected, whereas the temperature field is fully
three-dimensional. We identify two separate branches of convection close to
onset: (i) a well-known weak branch for Ekman numbers greater than $10^{-6}$,
which is continuous at the onset (supercritical bifurcation) and consists of
thermal Rossby waves, and (ii) a novel strong branch at lower Ekman numbers,
which is discontinuous at the onset. The strong branch becomes subcritical for
Ekman numbers of the order of $10^{-8}$. On the strong branch, the Reynolds
number of the flow is greater than $10^3$, and a strong zonal flow with
multiple jets develops, even close to the nonlinear onset of convection. We
find that the subcriticality is amplified by decreasing the Prandtl number. The
two branches can co-exist for intermediate Ekman numbers, leading to hysteresis
($Ek=10^{-6}$, $Pr=10^{-2}$). Nonlinear oscillations are observed near the
onset of convection for $Ek=10^{-7}$ and $Pr=10^{-1}$.


title:
A thermodynamically consistent model for multicomponent electrolyte
  solutions

abstract:
  This paper presents a thermodynamically consistent model for multicomponent
electrolyte solutions. The first part of this paper derives the general
governing equations for nonequilibrium systems within the theory of
nonequilibrium thermodynamics. Here, we consider electrolyte solutions as
general mixtures of charged constituents. Furthermore, in this part of the
paper we combine the general theory of nonequilibrium thermodynamics with the
well-known splittings of the entropy and the energy into a pure substance part
and a part due to mixing. Thereby, we successfully establish evolution
equations for both parts. Furthermore, we derive for both parts explicit
expressions of the respective entropy production rates. Hence, we provide an
approach that allows to study the entropy of mixing independently of the pure
substance entropy and vice versa. This is of great value, in particular for a
better understanding of the complex phenomena due to mixing in multicomponent
systems. In the second part of this paper, we close the system of general
balance equations by applying constitutive laws. This is the crucial step in
the modeling procedure. ...


title: High Resolution Laboratory Spectroscopy

abstract:
  In this short review we will highlight some of the recent advancements in the
field of high-resolution laboratory spectroscopy that meet the needs dictated
by the advent of highly sensitive and broadband telescopes like ALMA and SOFIA.
Among these is the development of broadband techniques for the study of complex
organic molecules, like fast scanning conventional absorption spectroscopy
based on multiplier chains, chirped pulse instrumentation, or the use of
synchrotron facilities. Of similar importance is the extension of the
accessible frequency range to THz frequencies, where many light hydrides have
their ground state rotational transitions. Another key experimental challenge
is the production of sufficiently high number densities of refractory and
transient species in the laboratory, where discharges have proven to be
efficient sources that can also be coupled to molecular jets. For ionic
molecular species sensitive action spectroscopic schemes have recently been
developed to overcome some of the limitations of conventional absorption
spectroscopy. Throughout this review examples demonstrating the strong
interplay between laboratory and observational studies will be given.


title:
Intra- and intercycle interference of electron emission in laser
  assisted XUV atomic ionization

abstract:
  We study the ionization of atomic hydrogen in the direction of polarization
due to a linearly polarized XUV pulse in the presence a strong field IR. We
describe the photoelectron spectra as an interference problem in the time
domain. Electron trajectories steming from different optical laser cycles give
rise to intercycle interference energy peaks known as sidebands. These
sidebands are modulated by a grosser structure coming from the intracycle
interference of the two electron trajectories born during the same optical
cycle. We make use of a simple semiclassical model which offers the possibility
to establish a connection between emission times and the photoelectron kinetic
energy. We compare the semiclassical predictions with the continuum-distorted
wave strong field approximation and the ab initio solution of the time
dependent Schr\"odinger equation. We analyze such interference pattern as a
function of the time delay between the IR and XUV pulse and also as a function
of the laser intensity.


title:
Scale Invariance at low accelerations (aka MOND) and the dynamical
  anomalies in the Universe

abstract:
  Galactic systems, and the Universe at large, exhibit large dynamical
anomalies: The observed matter in them falls very short of providing enough
gravity to account for their dynamics. The mainstream response to this
conundrum is to invoke large quantities of `dark matter' -- which purportedly
supplies the needed extra gravity -- and also of `dark energy', to account for
further anomalies in cosmology, such as the observed, accelerated expansion.
The MOND paradigm offers a different solution: a breakdown of standard dynamics
(gravity and/or inertia) in the limit of low accelerations -- below some
acceleration $a_0$. In this limit, dynamics become space-time scale invariant,
and is controlled by a gravitational constant $\mathcal{A}_0\equiv Ga_0$, which
replaces Newton's $G$. With the new dynamics, the various detailed
manifestations of the anomalies in galaxies are predicted with no need for dark
matter. The cosmological anomalies could, but need not have to do with small
accelerations. For example, the need for dark matter in accounting for the
expansion history of the Universe is eliminated if the relevant gravitational
constant is $\approx 2\pi G$. Such a `renormalization' of $G$ could be a
dimensionless parameter of a MOND theory. The constant $a_0$ turns out to carry
cosmological connotations, in that $2\pi a_0\approx cH_0\approx
c^2(\Lambda/3)^{1/2}$, where $H_0$ is the present expansion rate of the
Universe, and $\Lambda$ the measured `cosmological constant'. There are MOND
theories in which this `coincidence' is natural. I draw on enlightening
historical and conceptual analogies from quantum theory to limelight aspects of
MOND. I also explain how MOND may have strong connections with effects of the
quantum vacuum on local dynamics.


title: Conformal symmetry wormholes and the null energy condition

abstract:
  In this paper we seek a relationship between the assumption of conformal
symmetry and the exotic matter needed to hold a wormhole open. By starting with
a Morris-Thorne wormhole having a constant energy density, it is shown that the
conformal factor provides the extra degree of freedom sufficient to account for
the exotic matter. The same holds for Morris-Thorne wormholes in a
noncommutative-geometry setting. Applied to thin shells, there would exist a
radius that results in a wormhole with positive surface density and negative
surface pressure and which violates the null energy condition on the thin
shell.


title: Inside the perpendicular spin-torque memristor

abstract:
  Memristors are non-volatile nano-resistors. Their resistance can be tuned by
applied currents or voltages and set to a large number of levels between two
limit values. Thanks to these properties, memristors are ideal building blocks
for a number of applications such as multilevel non-volatile memories and
artificial nano-synapses, which are the focus of this work. A key point towards
the development of large scale memristive neuromorphic hardware is to build
these neural networks with a memristor technology compatible with the best
candidates for the future mainstream non-volatile memories. Here we show the
first experimental achievement of a memristor compatible with Spin-Torque
Magnetic Random Access Memory. The resistive switching in our spin-torque
memristor is linked to the displacement of a magnetic domain wall by
spin-torques in a perpendicularly magnetized magnetic tunnel junction. We
demonstrate that our magnetic synapse has a large number of intermediate
resistance states, sufficient for neural computation. Moreover, we show that
engineering the device geometry allows leveraging the most efficient spin
torque to displace the magnetic domain wall at low current densities and thus
to minimize the energy cost of our memristor. Our results pave the way for
spin-torque based analog magnetic neural computation.


title:
Magnetically-Assisted Slip Casting of Bioinspired Heterogeneous
  Composites

abstract:
  Composites are often made heterogeneous in nature to fulfill the functional
demands imposed by the environment, but remain difficult to fabricate
synthetically due to the lack of adequate and easily accessible processing
tools. We report on an additive manufacturing platform to fabricate
complex-shaped parts exhibiting bio-inspired heterogeneous microstructures with
locally tunable texture, composition and properties and unprecedentedly high
volume fractions of inorganic phase (up to 100%). The technology combines an
aqueous-based slip casting process with magnetically-directed particle assembly
to create programmed microstructural designs using anisotropic stiff platelets
in a ceramic, metal or polymer functional matrix. Using quantitative tools to
control the casting kinetics and the temporal pattern of the applied magnetic
fields, we demonstrate that this robust approach can be exploited to design and
fabricate heterogeneous composites with thus far inaccessible microstructures.
Proof-of-concept examples include bulk composites with periodic patterns of
micro-reinforcement orientation and tooth-like bilayer parts with intricate
shapes displaying site-specific composition and texture.


title:
Horizontal flow fields in and around a small active region-- The
  transition period between flux emergence and decay

abstract:
  Aims. Combining high-resolution and synoptic observations aims to provide a
comprehensive description of flux emergence at photospheric level and of the
growth process that eventually leads to a mature active region. Methods. Small
active region NOAA 12118 was observed on 2014 July 18 with the 1.5-meter GREGOR
solar telescope on 2014 July 18. High-resolution time-series of blue continuum
and G-band images acquired in the blue imaging channel (BIC) of the GREGOR
Fabry-P\'erot Interferometer (GFPI) were complemented by LOS magnetograms and
continuum images obtained with the HMI onboard the SDO. Horizontal proper
motions and horizontal plasma velocities were computed with local correlation
tracking (LCT) and the differential affine velocity estimator, respectively.
Morphological image processing was employed to measure the photometric/magnetic
area, magnetic flux, and the separation profile of the EFR during its
evolution. Results. The computed growth rates for photometric area, magnetic
area, and magnetic flux are about twice as high as the respective decay rates.
The space-time diagram using HMI magnetograms of five days traces a leaf-like
structure, which is determined by the initial separation of the two polarities,
a rapid expansion phase, a time when the spread stalls, and a period when the
region slowly shrinks again. The separation rate of 0.26 km\s is highest in the
initial stage, and it decreases when the separation comes to a halt. Horizontal
plasma velocities computed at four evolutionary stages indicate a changing
pattern of inflows. In LCT maps we find persistent flow patterns such as
outward motions in the outer part of the two major pores, a diverging feature
near the trailing pore marking the site of upwelling plasma and flux emergence,
and low velocities in the interior of pores. We detected many elongated rapidly
expanding granules between the two major polarities.


title:
Generation of Gamma-ray Beam with Orbital Angular Momentum in the QED
  Regime

abstract:
  We propose a scheme to generate gamma-ray photons with an orbital angular
momentum (OAM) and high energy simultaneously from laser-plasma interactions by
irradiating a circularly polarized Laguerre-Gaussian laser on a thin plasma
target. The spin angular momentum and OAM are first transferred to electrons
from the driving laser photons, and then the OAM is transferred to the
gamma-ray photons from the electrons through quantum radiation. This scheme has
been demonstrated using three-dimensional quantum electrodynamics
particle-in-cell simulation. The topological charge, chirality and
carrier-envelope phase of the short ultra-intense vortex laser can be revealed
according to the pattern feature of the energy density of radiated photons.


title: Exponential decay of scattering coefficients

abstract:
  We study an aspect of the following general question: which properties of a
signal can be characterized by its scattering transform? We show that the
energy contained in high order scattering coefficients is upper bounded by the
energy contained in the high frequencies of the signal. This result links the
decay of the scattering coefficients of a signal with the decay of its Fourier
transform. Additionally, it allows to generalize some results of Mallat (2012),
by relaxing the admissibility condition on the wavelet family.


title:
Impact of lexical and sentiment factors on the popularity of scientific
  papers

abstract:
  We investigate how textual properties of scientific papers relate to the
number of citations they receive. Our main finding is that correlations are
non-linear and affect differently most-cited and typical papers. For instance,
we find that in most journals short titles correlate positively with citations
only for the most cited papers, for typical papers the correlation is in most
cases negative. Our analysis of 6 different factors, calculated both at the
title and abstract level of 4.3 million papers in over 1500 journals, reveals
the number of authors, and the length and complexity of the abstract, as having
the strongest (positive) influence on the number of citations.


title:
Complex NMF under phase constraints based on signal modeling:
  application to audio source separation

abstract:
  Nonnegative Matrix Factorization (NMF) is a powerful tool for decomposing
mixtures of audio signals in the Time-Frequency (TF) domain. In the source
separation framework, the phase recovery for each extracted component is
necessary for synthesizing time-domain signals. The Complex NMF (CNMF) model
aims to jointly estimate the spectrogram and the phase of the sources, but
requires to constrain the phase in order to produce satisfactory sounding
results. We propose to incorporate phase constraints based on signal models
within the CNMF framework: a \textit{phase unwrapping} constraint that enforces
a form of temporal coherence, and a constraint based on the \textit{repetition}
of audio events, which models the phases of the sources within onset frames. We
also provide an algorithm for estimating the model parameters. The experimental
results highlight the interest of including such constraints in the CNMF
framework for separating overlapping components in complex audio mixtures.


title:
Phase reconstruction of spectrograms with linear unwrapping: application
  to audio signal restoration

abstract:
  This paper introduces a novel technique for reconstructing the phase of
modified spectrograms of audio signals. From the analysis of mixtures of
sinusoids we obtain relationships between phases of successive time frames in
the Time-Frequency (TF) domain. To obtain similar relationships over
frequencies, in particular within onset frames, we study an impulse model.
Instantaneous frequencies and attack times are estimated locally to encompass
the class of non-stationary signals such as vibratos. These techniques ensure
both the vertical coherence of partials (over frequencies) and the horizontal
coherence (over time). The method is tested on a variety of data and
demonstrates better performance than traditional consistency-based approaches.
We also introduce an audio restoration framework and observe that our technique
outperforms traditional methods.


title:
Phase reconstruction of spectrograms based on a model of repeated audio
  events

abstract:
  Phase recovery of modified spectrograms is a major issue in audio signal
processing applications, such as source separation. This paper introduces a
novel technique for estimating the phases of components in complex mixtures
within onset frames in the Time-Frequency (TF) domain. We propose to exploit
the phase repetitions from one onset frame to another. We introduce a reference
phase which characterizes a component independently of its activation times.
The onset phases of a component are then modeled as the sum of this reference
and an offset which is linearly dependent on the frequency. We derive a complex
mixture model within onset frames and we provide two algorithms for the
estimation of the model phase parameters. The model is estimated on
experimental data and this technique is integrated into an audio source
separation framework. The results demonstrate that this model is a promising
tool for exploiting phase repetitions, and point out its potential for
separating overlapping components in complex mixtures.


title:
Phase recovery in NMF for audio source separation: an insightful
  benchmark

abstract:
  Nonnegative Matrix Factorization (NMF) is a powerful tool for decomposing
mixtures of audio signals in the Time-Frequency (TF) domain. In applications
such as source separation, the phase recovery for each extracted component is a
major issue since it often leads to audible artifacts. In this paper, we
present a methodology for evaluating various NMF-based source separation
techniques involving phase reconstruction. For each model considered, a
comparison between two approaches (blind separation without prior information
and oracle separation with supervised model learning) is performed, in order to
inquire about the room for improvement for the estimation methods. Experimental
results show that the High Resolution NMF (HRNMF) model is particularly
promising, because it is able to take phases and correlations over time into
account with a great expressive power.


title:
Twisted superspace: Non-renormalization and fermionic symmetries in
  certain (heterotic string inspired) non-supersymmetric field theories

abstract:
  Inspired by the tachyon-free non-supersymmetric heterotic SO(16)xSO(16)
string we consider a special class of non-supersymmetric field theories: Those
that can be obtained from supersymmetric field theories by supersymmetry
breaking twists. We argue that such theories, like their supersymmetric counter
parts, may still possess some fermionic symmetries as left-overs of the super
gauge transformations and have special one-loop non-renormalization properties
due to holomorphicity. In addition, we extend the supergraph techniques to
these theories to calculate some explicit supersymmetry-breaking corrections.


title:
Attenuation and amplification of the transient current in nanojunctions
  with time-varying gate potentials

abstract:
  We study charge transport in a source-channel-drain system with a
time-varying applied gate potential acting on the channel. We calculate both
the current flowing from the source into the channel and out of the channel
into the drain. The current is expressed in terms of nonequilibrium Green's
functions. These nonequilibrium Green's functions can be determined from the
steady-state Green's functions and the equilibrium Green's functions of the
free leads. We find that the application of the gate potential can induce
current to flow even when there is no source-drain bias potential. However, the
direction of the current from the source and the current to the drain are
opposite, thereby resulting in no net current flowing within the channel. When
a source-drain bias potential is present, the net current flowing to the source
and drain can either be attenuated or amplified depending on the sign of the
applied gate potential. We also find that the response of the system to a
dynamically changing gate potential is not instantaneous, i.e., a relaxation
time has to pass before the current settles into a steady value. In particular,
when the gate potential is in the form of a step function, the current first
overshoots to a maximum value, oscillates, and then settles down to a
steady-state value.


abstract:
  Particle dynamics in the electron current layer in collisionless magnetic
reconnection is investigated by using a particle-in-cell simulation. Electron
motion and velocity distribution functions are studied by tracking
self-consistent trajectories. New classes of electron orbits are discovered:
figure-eight-shaped regular orbits inside the electron jet, noncrossing regular
orbits on the jet flanks, noncrossing Speiser orbits, and nongyrotropic
electrons in the downstream of the jet termination region. Properties of a
super-Alfv\'{e}nic outflow jet are attributed to an ensemble of electrons
traveling through Speiser orbits. Noncrossing orbits are mediated by the
polarization electric field near the electron current layer. The noncrossing
electrons are found to be non-negligible in number density. The impact of these
new orbits to electron mixing, spatial distribution of energetic electrons, and
observational signatures, is presented.


title:
On Asymptotics and Resurgent Structures of Enumerative Gromov-Witten
  Invariants

abstract:
  Making use of large-order techniques in asymptotics and resurgent analysis,
this work addresses the growth of enumerative Gromov-Witten invariants---in
their dependence upon genus and degree of the embedded curve---for several
different threefold Calabi-Yau varieties. In particular, while the leading
asymptotics of these invariants at large genus or at large degree is
exponential, at combined large genus and degree it turns out to be factorial.
This factorial growth has a resurgent nature, originating via mirror symmetry
from the resurgent-transseries description of the B-model free energy. This
implies the existence of nonperturbative sectors controlling the asymptotics of
the Gromov-Witten invariants, which could themselves have an
enumerative-geometry interpretation. The examples addressed include: the
resolved conifold; the local surfaces local P^2 and local P^1 x P^1; the local
curves and Hurwitz theory; and the compact quintic. All examples suggest very
rich interplays between resurgent asymptotics and enumerative problems in
algebraic geometry.


title: Instanton-dyon Ensembles III: Exotic Quark Flavors

abstract:
  "Exotic quarks" in the title refers to a modification of quark periodicity
condition on the thermal circle by introduction of some phases -- known also as
"flavor holonomies" -- different quark flavors. These phases provide a valuable
tool, to be used for better understanding of deconfinement and chiral
restoration phase transitions: by changing them one can dramatically modify
both phase transitions. In the language of instanton constituents --
instanton-dyons or monopoles -- it has a very direct explanation: the interplay
of flavor and color holonomies can switch topological zero modes between
various dyon types. The model we will study in detail, the so called
$Z_{N_c}$-symmetric QCD model with equal number of colors and flavors
$N_c=N_f=2$ and special arrangement of flavor and color holonomies, ensure
"most democratic" setting, in which each quark flavor and each dyon type are in
one-to-one correspondence. The usual QCD has the opposite "most exclusive"
arrangement: all quarks are antiperiodic and thus all zero modes fall on only
one -- twisted or $L$ -- dyon type. As we show by ensemble simulation,
deconfinement and chiral restoration phase transitions in these two models are
dramatically different. In the usual QCD both are smooth crossovers: but in the
case of $Z_2$-symmetric model deconfinement becomes strong first order
transition, while chiral symmetry remains broken for all dyon densities
studied. These results are in good correspondence with those from recent
lattice simulations.


title: The Feynman rules for neutrinos and new neutralinos in BLMSSM

abstract:
  In a supersymmetric extension of the standard model where baryon and lepton
numbers are local gauge symmetries(BLMSSM), we deduce the Feynman rules for
neutrinos and new neutralinos. We briey introduce the mass matrices for the
particles and the related couplings in this work, which are very useful to
research the neutrinos and new neutralinos.


title: Optimal control of many-body non-equilibrium quantum thermodynamics

abstract:
  We demonstrate the effectiveness of quantum optimal control techniques in
harnessing irreversibility generated by non-equilibrium processes, implemented
in unitarily evolving quantum many-body systems. We address the dynamics of a
finite-size quantum Ising model subjected to finite-time transformations, which
unavoidably generate irreversibility. We show that work can be generated
through such transformation by means of optimal controlled quenches, while
quenching the degree of irreversibility to very low values, thus boosting the
efficiency of the process and paving the way to a fully controllable
non-equilibrium thermodynamics of quantum processes.


title:
Syzygies of projective varieties of large degree: recent progress and
  open problems

abstract:
  This paper is a survey of recent work on the asymptotic behavior of the
syzygies of a smooth complex projective variety as the positivity of the
embedding line bundle grows.
  After a quick overview of results from the 1980s and 1990s concerning the
linearity of the first few terms of a resolution, we discuss a non-vanishing
theorem to the effect that from an asymptotic viewpoint, essentially all of the
syzygy modules that could be non-zero are in fact non-zero. We explain the
quick new proof of this result in the case of Veronese varieties due to Erman
and authors, and we explore some results and conjectures about the asymptotics
of Betti numbers. Finally we discuss the case of syzygies of weight one, and
the gonality conjecture on the syzygies of curves of large degree.
  The exposition also discusses numerous open questions and conjectures.


title: Storage enhanced nonlinearities in a cold atomic Rydberg ensemble

abstract:
  The combination of electromagnetically induced transparency (EIT) with the
nonlinear interaction between Rydberg atoms provides an effective interaction
between photons. In this paper, we investigate the storage of optical pulses as
collective Rydberg atomic excitations in a cold atomic ensemble. By measuring
the dynamics of the stored Rydberg polaritons, we experimentally demonstrate
that storing a probe pulse as Rydberg polaritons strongly enhances the Rydberg
mediated interaction compared to the slow propagation case. We show that the
process is characterized by two time scales. At short storage times, we observe
a strong enhancement of the interaction due to the reduction of the Rydberg
polariton group velocity down to zero. For longer storage times, we observe a
further, weaker enhancement dominated by Rydberg induced dephasing of the
multiparticle components of the state. In this regime, we observe a non-linear
dependence of the Rydberg polariton coherence time with the input photon
number. Our results have direct consequences in Rydberg quantum optics and
enable the test of new theories of strongly interacting Rydberg systems.


title: Communities as cliques

abstract:
  High-diversity assemblages are very common in nature, and yet the factors
allowing for the maintenance of biodiversity remain obscure. The competitive
exclusion principle and May's complexity-diversity puzzle both suggest that a
community can support only a small number of species, turning the spotlight at
the dynamics of local patches or islands, where stable and uninvadable (SU)
subsets of species play a crucial role. Here we map the community SUs question
to the geometric problem of finding maximal cliques of the corresponding graph.
We solve for the number of SUs as a function of the species richness in the
regional pool, $N$, showing that this growth is subexponential, contrary to
long-standing wisdom. We show that symmetric systems relax rapidly to an SU,
where the system stays until a regime shift takes place. In asymmetric systems
the relaxation time grows much faster with $N$, suggesting an excitable
dynamics under noise.


title:
Max-Min SINR in Large-Scale Single-Cell MU-MIMO: Asymptotic Analysis and
  Low Complexity Transceivers

abstract:
  This work focuses on the downlink and uplink of large-scale single-cell
MU-MIMO systems in which the base station (BS) endowed with $M$ antennas
communicates with $K$ single-antenna user equipments (UEs). Particularly, we
aim at reducing the complexity of the linear precoder and receiver that
maximize the minimum signal-to-interference-plus-noise ratio subject to a given
power constraint. To this end, we consider the asymptotic regime in which $M$
and $K$ grow large with a given ratio. Tools from random matrix theory (RMT)
are then used to compute, in closed form, accurate approximations for the
parameters of the optimal precoder and receiver, when imperfect channel state
information (modeled by the generic Gauss-Markov formulation form) is available
at the BS. The asymptotic analysis allows us to derive the asymptotically
optimal linear precoder and receiver that are characterized by a lower
complexity (due to the dependence on the large scale components of the channel)
and, possibly, by a better resilience to imperfect channel state information.
However, the implementation of both is still challenging as it requires fast
inversions of large matrices in every coherence period. To overcome this issue,
we apply the truncated polynomial expansion (TPE) technique to the precoding
and receiving vector of each UE and make use of RMT to determine the optimal
weighting coefficients on a per-UE basis that asymptotically solve the max-min
SINR problem. Numerical results are used to validate the asymptotic analysis in
the finite system regime and to show that the proposed TPE transceivers
efficiently mimic the optimal ones, while requiring much lower computational
complexity.


title:
An altitude and distance correction to the source fluence distribution
  of TGFs

abstract:
  The source fluence distribution of terrestrial gamma ray flashes (TGFs) has
been extensively discussed in recent years, but few have considered how the TGF
fluence distribution at the source, as estimated from satellite measurements,
depends on the distance from satellite foot point and assumed production
altitude. As the absorption of the TGF photons increases significantly with
lower source altitude and larger distance between the source and the observing
satellite, these might be important factors. We have addressed the issue by
using the tropopause pressure distribution as an approximation of the TGF
production altitude distribution and World Wide Lightning Location Network
spheric measurements to determine the distance. The study is made possible by
the increased number of Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
TGFs found in the second catalog of the RHESSI data. One find is that the
TGF/lightning ratio for the tropics probably has an annual variability due to
an annual variability in the Dobson-Brewer circulation. The main result is an
indication that the altitude distribution and distance should be considered
when investigating the source fluence distribution of TGFs, as this leads to a
softening of the inferred distribution of source brightness.


title:
Crystal Growth of new charge-transfer salts based on $\pi$-conjugated
  molecules

abstract:
  New charge transfer crystals of $\pi$-conjugated, aromatic molecules
(phenanthrene and picene) as donors were obtained by physical vapor transport.
The melting behavior, optimization of crystal growth and the crystal structure
is reported for charge transfer salts with (fluorinated)
tetracyanoquinodimethane (TCNQ-F$_x$, x=0, 2, 4), which was used as acceptor
material. The crystal structures were determined by single-crystal X-ray
diffraction. Growth conditions for different vapor pressures in closed ampules
were applied and the effect of these starting conditions for crystal size and
quality is reported. The process of charge transfer was investigated by
geometrical analysis of the crystal structure and by infrared spectroscopy on
single crystals. With these three different acceptor strengths and the two sets
of donor materials, it is possible to investigate the distribution of the
charge transfer systematically. This helps to understand the charge transfer
process in this class of materials with $\pi$-conjugated donor molecules.


title: When should an expert make a prediction?

abstract:
  We consider a setting where in a known future time, a certain continuous
random variable will be realized. There is a public prediction that gradually
converges to its realized value, and an expert that has access to a more
accurate prediction. Our goal is to study {\em when} should the expert reveal
his information, assuming that his reward is based on a logarithmic market
scoring rule (i.e., his reward is proportional to the gain in log-likelihood of
the realized value).
  Our contributions are: (1) we characterize the expert's optimal policy and
show that it is threshold based. (2) we analyze the expert's asymptotic
expected optimal reward and show a tight connection to the Law of the Iterated
Logarithm, and (3) we give an efficient dynamic programming algorithm to
compute the optimal policy.


title:
A natural constraint approach to normalized solutions of nonlinear
  Schr\"odinger equations and systems

abstract:
  We prove existence of normalized solutions to \[ \begin{cases} -\Delta u -
\lambda_1 u = \mu_1 u^3+ \beta u v^2 & \text{in $\mathbb{R}^3$} -\Delta v-
\lambda_2 v = \mu_2 v^3 +\beta u^2 v & \text{in
$\mathbb{R}^3$}\int_{\mathbb{R}^3} u^2 = a_1^2 \quad \text{and} \quad
\int_{\mathbb{R}^3} v^2 = a_2^2 \end{cases} \] for any $\mu_1,\mu_2,a_1,a_2>0$
and $\beta<0$ prescribed. The approach is based upon the introduction of a
natural constraint associated to the problem.
  Our method can be adapted to the scalar NLS equation with normalization
constraint, and leads to alternative and simplified proofs to some results
already available in the literature.


title:
Measurement of the relative width difference of the $B^0$-$\bar B^0$
  system with the ATLAS detector

abstract:
  This paper presents the measurement of the relative width difference $\Delta
\Gamma_d / \Gamma_d$ of the $B^0$-$\bar B^0$ system using the data collected by
the ATLAS experiment at the LHC in $p p$ collisions at $\sqrt{s} = 7$ TeV and
$\sqrt{s} = 8$ TeV and corresponding to an integrated luminosity of 25.2
fb$^{-1}$. The value of $\Delta \Gamma_d / \Gamma_d$ is obtained by comparing
the decay-time distributions of $B^0 \to J/\psi K_S$ and $B^0 \to J/\psi
K^{*0}(892)$ decays. The result is $\Delta \Gamma_d / \Gamma_d = (-0.1 \pm
1.1~\mbox{(stat.)} \pm 0.9~\mbox{(syst.)}) \times 10^{-2}$. Currently, this is
the most precise single measurement of $\Delta \Gamma_d / \Gamma_d$. It agrees
with the Standard Model prediction and the measurements by other experiments.


title:
Explicit projective embeddings of standard opens of the Hilbert scheme
  of points

abstract:
  We describe explicitly how certain standard opens of the Hilbert scheme of
points are embedded into Grassmannians. The standard opens of the Hilbert
scheme that we consider are given as the intersection of a corresponding basic
open affine of the Grassmannian and a closed stratum determined by a Fitting
ideal.


title: Dielectric Resonator Metasurface for Dispersion Engineering

abstract:
  We introduce a practical dielectric metasurface design for microwave
frequencies. The metasurface is made of an array of dielectric resonators held
together by dielectric connections thus avoiding the need of a mechanical
support in the form of a dielectric slab and the spurious multiple reflections
that such a slab would generate. The proposed design can be used either for
broadband metasurface applications or monochromatic wave transformations. The
capabilities of the concept to manipulate the transmission phase and amplitude
of the metasurface are supported by numerical and experimental results.
Finally, a half-wave plate and a quarter-wave plate have been realized with the
proposed concept.


title:
Transcriptional Similarity in Couples Reveals the Impact of Shared
  Environment and Lifestyle on Gene Regulation through Modified Cytosines

abstract:
  Gene expression is a complex and quantitative trait that is influenced by
both genetic and non-genetic regulators including environmental factors.
Evaluating the contribution of environment to gene expression regulation and
identifying which genes are more likely to be influenced by environmental
factors are important for understanding human complex traits. We hypothesize
that by living together as couples, there can be commonly co-regulated genes
that may reflect the shared living environment (e.g., diet, indoor air
pollutants, behavioral lifestyle). The lymphoblastoid cell lines (LCLs) derived
from unrelated couples of African ancestry (YRI, Yoruba people from Ibadan,
Nigeria) from the International HapMap Project provided a unique model for us
to characterize gene expression pattern in couples by comparing gene expression
levels between husbands and wives. Strikingly, 778 genes were found to show
much smaller variances in couples than random pairs of individuals at a false
discovery rate (FDR) of 5%. Since genetic variation between unrelated family
members in a general population is expected to be the same assuming a
random-mating society, non-genetic factors (e.g., epigenetic systems) are more
likely to be the mediators for the observed transcriptional similarity in
couples. We thus evaluated the contribution of modified cytosines to those
genes showing transcriptional similarity in couples as well as the
relationships these CpG sites with other gene regulatory elements, such as
transcription factor binding sites (TFBS). Our findings suggested that
transcriptional similarity in couples likely reflected shared common
environment partially mediated through cytosine modifications.


title:
Interplay of screening and superconductivity in low-dimensional
  materials

abstract:
  A quantitative description of Coulomb interactions is developed for
two-dimensional superconducting materials, enabling us to compare intrinsic
with external screening effects, such as those due to substrates. Using the
example of a doped monolayer of MoS2 embedded in a tunable dielectric
environment, we demonstrate that the influence of external screening is limited
to a length scale, bounded from below by the effective thickness of the
quasi-two-dimensional material and from above by its intrinsic screening
length. As a consequence, it is found that unconventional Coulomb-driven
superconductivity cannot be induced in MoS2 by tuning the substrate properties
alone. Our calculations of the retarded Morel-Anderson Coulomb potential {\mu
*} reveal that the Coulomb interactions, renormalized by the reduced layer
thickness and the substrate properties, can shift the onset of the
electron-phonon driven superconducting phase in monolayer MoS2 but do not
significantly affect the critical temperature at optimal doping.


title: Artificial piezoelectricity in centrosymmetric SrTiO3

abstract:
  Defect engineering is an effective and powerful tool to control existing
material properties and create completely new ones, which are
symmetry-forbidden in a defect-free crystal. This letter reports on the
creation of piezoelectrically active near-surface layer of centrosymmetric
SrTiO3, modified by the electric field-induced migration of oxygen vacancies.
We provide the unequivocal proof of piezoelectricity through the stroboscopic
time-resolved X-ray diffraction under alternating electric field. The magnitude
of the discovered piezoelectric effect is comparable with the bulk
piezoelectric effect in commercial ferroelectric materials. Such artificially
formed defect-mediated piezoelectricity can be important as an alternative road
for smart materials design.


title:
An action of the Hecke monoid on rational modules for the Borel subgroup
  of a quantised general linear group

abstract:
  We construct an action of the Hecke monoid on the category of rational
modules for the quantum negative Borel subgroup of the quantum general linear
group. We also show that this action restricts to the category of polynomial
modules for this quantum subgroup and induces an action on the category of
modules for quantised Borel-Schur algebras.


title: Ramsey Numbers of Connected Clique Matchings

abstract:
  We determine the Ramsey number of a connected clique matching. That is, we
show that if $G$ is a $2$-edge-coloured complete graph on $(r^2 - r - 1)n - r +
1$ vertices, then there is a monochromatic connected subgraph containing $n$
disjoint copies of $K_r$, and that this number of vertices cannot be reduced.


title:
Safely Optimizing Highway Traffic with Robust Model Predictive
  Control-based Cooperative Adaptive Cruise Control

abstract:
  Road traffic crashes have been the leading cause of death among young people.
Most of these accidents occur when the driver becomes distracted due to fatigue
or external factors. Vehicle platooning systems such as Cooperative Adaptive
Cruise Control (CACC) are one of the results of the effort devoted to the
development of technologies for decreasing the number of road crashes and
fatalities. Previous studies have suggested such systems improve up to 273\%
highway traffic throughput and fuel consumption in more than 15\% if the
clearance between vehicles in this class of roads can be reduced to 2 meters.
This paper proposes an approach that guarantees a minimum safety distance
between vehicles taking into account the overall system delays and braking
capacity of each vehicle. A $l\infty$-norm Robust Model Predictive Controller
(RMPC) is developed to guarantee the minimum safety distance is not violated
due to uncertainties on the lead vehicle behavior. A formulation for a lower
bound clearance of vehicles inside a platoon is also proposed. Simulation
results show the performance of the proposed approach compared to a nominal
controller when the system is subject to both modeled and unmodeled
disturbances.


title: On positive loops of loose Legendrian embeddings

abstract:
  In this paper, via h-principle we prove that there exist contractible
positive loops of Legendrian embeddings based at any loose Legendrian
submanifold. As an application, we define a new partial order on
$\widetilde{Cont}_0(M,\xi)$ and prove that overtwisted contact manifolds are
weakly non-orderable.


title:
Optimal Deployment of Multistatic Radar System Using Multi-Objective
  Particle Swarm Optimization

abstract:
  We consider an optimization deployment problem of multistatic radar system
(MSRS). Through the antenna placing and the transmitted power allocating, we
optimally deploy the MSRS for two goals: 1) the first one is to improve the
coverage ratio of surveillance region; 2) the second goal is to get a even
distribution of signal energy in surveillance region. In two typical working
modes of MSRS, we formulate the optimization problem by introducing two
objective functions according to the two mentioned goals, respectively.
Addressing on two main challenges of applying multi-objective particle swarm
optimization (MOPSO) in solving the proposed optimization problem, we propose a
deployment algorithm based on multiobjective particle swarm optimization with
non-dominated relative crowding distance (MOPSO-NRCD). For the challenge of
value difference, we propose a novel selection method with a non-dominated
relative crowding distance. For the challenge of particle allocation, a
multi-swarm structure of MOPSO is also introduced. Finally, simulation results
are given out to prove the advantages and validity of the proposed deployment
algorithm. It is shown that with same number of employed particles, the
proposed MOPSO-NRCD algorithm can achieve better optimization performance than
that of traditional multiobjective particle swarm optimization with crowding
distance (MOPSO-CD).


title: Alternating Optimisation and Quadrature for Robust Control

abstract:
  Bayesian optimisation has been successfully applied to a variety of
reinforcement learning problems. However, the traditional approach for learning
optimal policies in simulators does not utilise the opportunity to improve
learning by adjusting certain environment variables: state features that are
unobservable and randomly determined by the environment in a physical setting
but are controllable in a simulator. This paper considers the problem of
finding a robust policy while taking into account the impact of environment
variables. We present Alternating Optimisation and Quadrature (ALOQ), which
uses Bayesian optimisation and Bayesian quadrature to address such settings.
ALOQ is robust to the presence of significant rare events, which may not be
observable under random sampling, but play a substantial role in determining
the optimal policy. Experimental results across different domains show that
ALOQ can learn more efficiently and robustly than existing methods.


title: A weak-coupling master equation for arbitrary initial conditions

abstract:
  The structure of the initial system-environment state is fundamental to
determining the nature and characteristics of the evolution of such an open
quantum system. The usual assumption is to consider that the initial
system-environment state is separable. Here, we go beyond this simple case and
derive the evolution equations, up to second order in a weak-coupling
expansion, that describe the evolution of the reduced density matrix of the
system for any arbitrary system-environment initial state. The structure of
these equations allows us to determine the initial conditions for which a
Lindblad form can be recovered once applying the Markov and secular
approximations.


title: Leveraging Over Priors for Boosting Control of Prosthetic Hands

abstract:
  The Electromyography (EMG) signal is the electrical activity produced by
cells of skeletal muscles in order to provide a movement. The non-invasive
prosthetic hand works with several electrodes, placed on the stump of an
amputee, that record this signal. In order to favour the control of prosthesis,
the EMG signal is analyzed with algorithms based on machine learning theory to
decide the movement that the subject is going to do. In order to obtain a
significant control of the prosthesis and avoid mismatch between desired and
performed movements, a long training period is needed when we use the
traditional algorithm of machine learning (i.e. Support Vector Machines). An
actual challenge in this field concerns the reduction of the time necessary for
an amputee to learn how to use the prosthesis. Recently, several algorithms
that exploit a form of prior knowledge have been proposed. In general, we refer
to prior knowledge as a past experience available in the form of models. In our
case an amputee, that attempts to perform some movements with the prosthesis,
could use experience from different subjects that are already able to perform
those movements. The aim of this work is to verify, with a computational
investigation, if for an amputee this kind of previous experience is useful in
order to reduce the training time and boost the prosthetic control.
Furthermore, we want to understand if and how the final results change when the
previous knowledge of intact or amputated subjects is used for a new amputee.
Our experiments indicate that: (1) the use of experience, from other subjects
already trained to perform a task, makes us able to reduce the training time of
about an order of magnitude; (2) it seems that an amputee that tries to learn
to use the prosthesis doesn't reach different results when he/she exploits
previous experience of amputees or intact.


title:
Comment on "Structure effects in the $^{15}$N(n,$\gamma$)$^{16}$N
  radiative capture reaction from the Coulomb dissociation of $^{16}$N"

abstract:
  In their recent study Neelam, Shubhchintak, and Chatterjee have claimed that
"it would certainly be useful to perform a Coulomb dissociation experiment to
find the low energy capture cross section for the reaction"
$^{15}$N(n,$\gamma$)$^{16}$N. However, it is obvious that a Coulomb
dissociation experiment cannot constrain this capture cross section because the
dominating branchings of the capture reaction lead to excited states in
$^{16}$N which do not contribute in a Coulomb dissociation experiment. An
estimate of the total $^{15}$N(n,$\gamma$)$^{16}$N cross section from Coulomb
dissociation of $^{16}$N requires a precise knowledge of the $\gamma$-ray
branchings in the capture reaction. Surprisingly, the calculation of Neelam,
Shubhchintak, and Chatterjee predicts a strongly energy-dependent ground state
branching of the order of 0.05\% to 0.6\% at energies between 100 and 500 keV
which is almost 2 orders of magnitude below calculations in the direct capture
model. Additionally, this calculation of Neelam, Shubhchintak, and Chatterjee
deviates significantly from the expected energy dependence for $p$-wave
capture.


title: Pathwise Iteration for Backward SDEs

abstract:
  We introduce a novel numerical approach for a class of stochastic dynamic
programs which arise as discretizations of backward stochastic differential
equations or semi-linear partial differential equations. Solving such dynamic
programs numerically requires the approximation of nested conditional
expectations, i.e., iterated integrals of previous approximations. Our approach
allows us to compute and iteratively improve upper and lower bounds on the true
solution starting from an arbitrary and possibly crude input approximation. We
demonstrate the benefits of our approach in a high dimensional financial
application.


title: IVOA Identifiers Version 2.0

abstract:
  An IVOA Identifier is a globally unique name for a resource within the
Virtual Observatory. This name can be used to retrieve a unique description of
the resource from an IVOA-compliant registry or to identify an entity like a
dataset or a protocol without dereferencing the identifier. This document
describes the syntax for IVOA Identifiers as well as how they are created. The
syntax has been defined to encourage global-uniqueness naturally and to
maximize the freedom of resource providers to control the character content of
an identifier.


title:
Nucleosynthesis of $^{92}$Nb and the relevance of the low-lying isomer
  at 135.5 keV

abstract:
  Background: Because of its half-life of about 35 million years, 92Nb is
considered as a chronometer for nucleosynthesis events prior to the birth of
our sun. The abundance of 92Nb in the early solar system can be derived from
meteoritic data. It has to be compared to theoretical estimates for the
production of 92Nb to determine the time between the last nucleosynthesis event
before the formation of the early solar system.
  Purpose: The influence of a low-lying short-lived isomer on the
nucleosynthesis of 92Nb is analyzed. The thermal coupling between the ground
state and the isomer via so-called intermediate states affects the production
and survival of 92Nb.
  Method: The properties of the lowest intermediate state in 92Nb are known
from experiment. From the lifetime of the intermediate state and from its decay
branchings, the transition rate from the ground state to the isomer and the
effective half-life of 92Nb are calculated as a function of the temperature.
  Results: The coupling between the ground state and the isomer is strong. This
leads to thermalization of ground state and isomer in the nucleosynthesis of
92Nb in any explosive production scenario and almost 100% survival of 92Nb in
its ground state. However, the strong coupling leads to a temperature-dependent
effective half-life of 92Nb which makes the 92Nb survival very sensitive to
temperatures as low as about 8 keV, thus turning 92Nb at least partly into a
thermometer.
  Conclusions: The low-lying isomer in 92Nb does not affect the production of
92Nb in explosive scenarios. In retrospect this validates all previous studies
where the isomer was not taken into account. However, the dramatic reduction of
the effective half-life at temperatures below 10 keV may affect the survival of
92Nb after its synthesis in supernovae which are the most likely astrophysical
site for the nucleosynthesis of 92Nb.


title:
A novel algorithm for solving the Decision Boolean Satisfiability
  Problem without algebra

abstract:
  This paper depicts an algorithm for solving the Decision Boolean
Satisfiability Problem using the binary numerical properties of a Special
Decision Satisfiability Problem, parallel execution, object oriented, and short
termination. The two operations: expansion and simplification are used to
explains why using algebra grows the resolution steps. It is proved that its
complexity has an upper bound of $2^{n-1}$ where $n$ is the number of logical
variables of the given problem.


title:
Nanometre scale monitoring of the quantum confined stark effect and
  emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

abstract:
  We report on a detailed study of the intensity dependent optical properties
of individual GaN/AlN Quantum Disks (QDisks) embedded into GaN nanowires (NW).
The structural and optical properties of the QDisks were probed by high spatial
resolution cathodoluminescence (CL) in a scanning transmission electron
microscope (STEM). By exciting the QDisks with a nanometric electron beam at
currents spanning over 3 orders of magnitude, strong non-linearities (energy
shifts) in the light emission are observed. In particular, we find that the
amount of energy shift depends on the emission rate and on the QDisk morphology
(size, position along the NW and shell thickness). For thick QDisks (>4nm), the
QDisk emission energy is observed to blue-shift with the increase of the
emission intensity. This is interpreted as a consequence of the increase of
carriers density excited by the incident electron beam inside the QDisks, which
screens the internal electric field and thus reduces the quantum confined Stark
effect (QCSE) present in these QDisks. For thinner QDisks (<3 nm), the
blue-shift is almost absent in agreement with the negligible QCSE at such
sizes. For QDisks of intermediate sizes there exists a current threshold above
which the energy shifts, marking the transition from unscreened to partially
screened QCSE. From the threshold value we estimate the lifetime in the
unscreened regime. These observations suggest that, counterintuitively,
electrons of high energy can behave ultimately as single electron-hole pair
generators. In addition, when we increase the current from 1 pA to 10 pA the
light emission efficiency drops by more than one order of magnitude. This
reduction of the emission efficiency is a manifestation of the efficiency droop
as observed in nitride-based 2D light emitting diodes, a phenomenon tentatively
attributed to the Auger effect.


title:
An Efficient Likelihood-Based Modulation Classification Algorithm for
  MIMO Systems

abstract:
  Blind algorithms for multiple-input multiple-output (MIMO) signals
interception have recently received considerable attention because of their
important applications in modern civil and military communication fields. One
key step in the interception process is to blindly recognize the modulation
type of the MIMO signals. This can be performed by employing a Modulation
Classification (MC) algorithm, which can be feature-based or likelihood-based.
To overcome the problems associated with the existing likelihood-based MC
algorithms, a new algorithm is developed in this paper. We formulated the MC
problem as maximizing a global likelihood function formed by combining the
likelihood functions for the estimated transmitted signals, where Minimum Mean
Square Error (MMSE) filtering is employed to separate the MIMO channel into
several sub-channels. Simulation results showed that the proposed algorithm
works well under various operating conditions, and performs close to the
performance upper bound with reasonable complexity.


title:
Properties of the zero energy Andreev bound state in a two sublattice
  SNS junction

abstract:
  We study properties of the zero energy Andreev bound state in a
superconductor-normal metal-superconductor(SNS) junction consisting of two
intrinsic degrees of freedom. The superconductors on either sides of the normal
metal are assumed to have two sublattices with an $intra$-sublattice pairing
with a phase of zero or $\pi$ between the two sublattices. In addition, we add
a uniform $inter$-sublattice pairing and study its effect on the local density
of states (LDOS). In particular, we find that as the inter-sublattice pairing
is turned on, the zero bias peak (ZBP) is unstable (robust) when the phase
difference across the sublattices is $\pi$ (zero). We discuss the relevance of
our results to the recently proposed odd parity $-\eta$ pairing ground states
in Iron based superconductors (FeSCs).


title:
The asymptotics of the analytic torsion on CR manifolds with $S^1$
  action

abstract:
  Let $X$ be a compact connected strongly pseudoconvex CR manifold of dimension
$2n+1, n \ge 1$ with a transversal CR $S^1$-action on $X$. We introduce the
Fourier components of the Ray-Singer analytic torsion on $X$ with respect to
the $S^1$-action. We establish an asymptotic formula for the Fourier components
of the analytic torsion with respect to the $S^1$-action. This generalizes the
asymptotic formula of Bismut and Vasserot on the holomorphic Ray-Singer torsion
associated with high powers of a positive line bundle to strongly pseudoconvex
CR manifolds with a transversal CR $S^1$-action.


title: Autocatalytic mechanism of pearlite transformation in steel

abstract:
  A model of pearlite colony formation in carbon steels with ab-initio
parameterization is proposed. The model describes the process of decomposition
of austenite and cementite formation through a metastable intermediate
structure by taking into account the increase of the magnetic order under the
cooling. Autocatalytic mechanism of pearlite colony formation and the
conditions for its implementation have been analyzed. We demonstrate that
pearlite with lamellar structure is formed by autocatalytic mechanism when
thermodynamic equilibrium between the initial phase (austenite) and the
products of its decomposition (cementite and ferrite) does not take place. By
using model expression for free energy with first-principles parameterization
we find conditions of formation of both lamellar and globular structures, in
agreement with experiment. The transformation diagram is suggested and
different scenarios in the kinetics of decomposition are investigated by phase
field simulations.


title: Results on heavy ion collisions at LHCb

abstract:
  Heavy flavor production is important in heavy ion collisions to study both
cold and hot nuclear matter effects. The LHCb experiment can make unique
contribution to heavy ion physics, owing to the full particle identification of
the detector in the forward region and the ability to collect fixed target data
with proton or lead beams. This report describes recent results with
proton-lead collision data collected in 2013 and the prospect of heavy-ion
studies at LHCb.


title: 6D Interpretation of 3D Gravity

abstract:
  We show that 3D gravity, in its pure connection formulation, admits a natural
6D interpretation. The 3D field equations for the connection are equivalent to
6D Hitchin equations for the Chern-Simons 3-form in the total space of the
principal bundle over the 3-dimensional base. Turning this construction around
one gets an explanation of why the pure connection formulation of 3D gravity
exists. More generally, we interpret 3D gravity as the dimensional reduction of
the 6D Hitchin theory. To this end, we show that any SU(2) invariant closed
3-form in the total space of the principal SU(2) bundle can be parametrised by
a connection together with a 2-form field on the base. The dimensional
reduction of the 6D Hitchin theory then gives rise to 3D gravity coupled to a
topological 2-form field.


title: A note on privacy preserving iteratively reweighted least squares

abstract:
  Iteratively reweighted least squares (IRLS) is a widely-used method in
machine learning to estimate the parameters in the generalised linear models.
In particular, IRLS for L1 minimisation under the linear model provides a
closed-form solution in each step, which is a simple multiplication between the
inverse of the weighted second moment matrix and the weighted first moment
vector. When dealing with privacy sensitive data, however, developing a privacy
preserving IRLS algorithm faces two challenges. First, due to the inversion of
the second moment matrix, the usual sensitivity analysis in differential
privacy incorporating a single datapoint perturbation gets complicated and
often requires unrealistic assumptions. Second, due to its iterative nature, a
significant cumulative privacy loss occurs. However, adding a high level of
noise to compensate for the privacy loss hinders from getting accurate
estimates. Here, we develop a practical algorithm that overcomes these
challenges and outputs privatised and accurate IRLS solutions. In our method,
we analyse the sensitivity of each moments separately and treat the matrix
inversion and multiplication as a post-processing step, which simplifies the
sensitivity analysis. Furthermore, we apply the {\it{concentrated differential
privacy}} formalism, a more relaxed version of differential privacy, which
requires adding a significantly less amount of noise for the same level of
privacy guarantee, compared to the conventional and advanced compositions of
differentially private mechanisms.


title: Green Cloudlet Network: A Distributed Green Mobile Cloud Network

abstract:
  This article introduces a Green Cloudlet Network (GCN) architecture in the
context of mobile cloud computing. The proposed architecture is aimed at
providing seamless and low End-to-End (E2E) delay between a User Equipment (UE)
and its Avatar (its software clone) in the cloudlets to facilitate the
application workloads offloading process. Furthermore, Software Define
Networking (SDN) based core network is introduced in the GCN architecture by
replacing the traditional Evolved Packet Core (EPC) in the LTE network in order
to provide efficient communications connections between different end points.
Cloudlet Network File System (CNFS) is designed based on the proposed
architecture in order to protect Avatars' dataset against hardware failure and
improve the Avatars' performance in terms of data access latency. Moreover,
green energy supplement is proposed in the architecture in order to reduce the
extra Operational Expenditure (OPEX) and CO2 footprint incurred by running the
distributed cloudlets. Owing to the temporal and spatial dynamics of both the
green energy generation and energy demands of Green Cloudlet Systems (GCSs),
designing an optimal green energy management strategy based on the
characteristics of the green energy generation and the energy demands of eNBs
and cloudlets to minimize the on-grid energy consumption is critical to the
cloudlet provider.


title:
Probing the sign of on-site Hubbard interaction by two-particle quantum
  walks

abstract:
  We consider two identical bosons propagating on a one-dimensional lattice and
address the prob- lem of discriminating whether their mutual on-site
interaction is attractive or repulsive. We suggest a probing scheme based on
the properties of the corresponding two-particle quantum walks, and show that
the sign of the interaction introduces specific and detectable features in the
dynamics of quantum correlations, thus permitting to discriminate between the
two cases. We also discuss how these features are connected to the
band-structure of the Hubbard Hamiltonian, and prove that discrimination may be
obtained only when the two walkers are initially prepared in a superposition of
localized states.


title: An empirical Bayes approach to network recovery using external knowledge

abstract:
  Reconstruction of a high-dimensional network may benefit substantially from
the inclusion of prior knowledge on the network topology. In the case of gene
interaction networks such knowledge may come for instance from pathway
repositories like KEGG, or be inferred from data of a pilot study. The Bayesian
framework provides a natural means of including such prior knowledge. Based on
a Bayesian Simultaneous Equation Model, we develop an appealing empirical Bayes
procedure which automatically assesses the relevance of the used prior
knowledge. We use variational Bayes method for posterior densities
approximation and compare its accuracy with that of Gibbs sampling strategy.
Our method is computationally fast, and can outperform known competitors. In a
simulation study we show that accurate prior data can greatly improve the
reconstruction of the network, but need not harm the reconstruction if wrong.
We demonstrate the benefits of the method in an analysis of gene expression
data from GEO. In particular, the edges of the recovered network have superior
reproducibility (compared to that of competitors) over resampled versions of
the data.


title: Neural Semantic Role Labeling with Dependency Path Embeddings

abstract:
  This paper introduces a novel model for semantic role labeling that makes use
of neural sequence modeling techniques. Our approach is motivated by the
observation that complex syntactic structures and related phenomena, such as
nested subordinations and nominal predicates, are not handled well by existing
models. Our model treats such instances as sub-sequences of lexicalized
dependency paths and learns suitable embedding representations. We
experimentally demonstrate that such embeddings can improve results over
previous state-of-the-art semantic role labelers, and showcase qualitative
improvements obtained by our method.


title:
Robust phase retrieval with the swept approximate message passing
  (prSAMP) algorithm

abstract:
  In phase retrieval, the goal is to recover a complex signal from the
magnitude of its linear measurements. While many well-known algorithms
guarantee deterministic recovery of the unknown signal using i.i.d. random
measurement matrices, they suffer serious convergence issues some
ill-conditioned matrices. As an example, this happens in optical imagers using
binary intensity-only spatial light modulators to shape the input wavefront.
The problem of ill-conditioned measurement matrices has also been a topic of
interest for compressed sensing researchers during the past decade. In this
paper, using recent advances in generic compressed sensing, we propose a new
phase retrieval algorithm that well-adopts for both Gaussian i.i.d. and binary
matrices using both sparse and dense input signals. This algorithm is also
robust to the strong noise levels found in some imaging applications.


title: Generalized Kadanoff-Baym relation in nonequilibrium quenched models

abstract:
  In the context of a broad class of quenched models, we derive a generalized
differential form of the Kadanoff-Baym (KB) ansatz which relates the out of
equilibrium correlated and spectral Green's functions. This relation holds at
any time both before the quench (when it coincides with the
fluctuation-dissipation theorem) as well as after it. We also examine, in the
context of exactly soluble quenched models, the validity of some of the earlier
alternative extensions of the KB ansatz.


title:
High-frequency excess in the radio continuum spectrum of the type-1
  Seyfert galaxy NGC 985

abstract:
  The Seyfert galaxy NGC 985 is known to show a high-frequency excess in its
radio continuum spectrum in a milli-Jansky level on the basis of previous
observations at 1.4--15 GHz; a steep spectrum at low frequencies (a spectral
index of $\alpha=-1.10 \pm 0.03$) changes at ~10 GHz into an inverted spectrum
at higher frequencies ($\alpha=+0.86 \pm 0.09$). We conduct new observations at
15--43 GHz using the Very Large Array and at 100 GHz using the Nobeyama
Millimeter Array. As a result, the high-frequency excess continuing at even
higher radio frequencies up to 43 GHz has been confirmed. The non-detection at
100 GHz was not so strong constraint, and therefore the spectral behavior above
43 GHz remains unclear. The astrometric position of the high-frequency excess
component coincides with the optical position of the Seyfert nucleus and the
low-frequency radio position to an accuracy of 0.1 arcsec, corresponding to ~80
pc; the radio source size is constrained to be <0.02 arcsec, corresponding to
<16 pc. We discuss the physical origin of the observed high-frequency excess
component. Dust emission at the Rayleigh-Jeans regime, free--free emission from
X-ray radiating high-temperature plasma, free--free emission from the ensemble
of broad-line region clouds, or thermal synchrotron from hot accretion flow
cannot be responsible for the observed radio flux. Compact jets under
synchrotron self-absorption may be unlikely in terms of observed time scales.
Alternatively, we cannot rule out the hypotheses of synchrotron jets free--free
absorbed by a circumnuclear photo-ionized region, and self-absorbed nonthermal
synchrotron from disk corona, as the origin of the high-frequency excess
component.


title: Delayed stability switches in singularly perturbed predator-prey models

abstract:
  In this paper we provide an elementary proof of the existence of canard
solutions for a class of singularly perturbed predator-prey planar systems in
which there occurs a transcritical bifurcation of quasi steady states. The
proof uses a one-dimensional theory of canard solutions developed by V. F.
Butuzov, N. N. Nefedov and K. R. Schneider, and an appropriate monotonicity
assumption on the vector field to extend it to the two-dimensional case. The
result is applied to identify all possible predator-prey models with quadratic
vector fields allowing for the existence of canard solutions.


title:
Nonparametric estimation of a regression function using the gamma kernel
  method in ergodic processes

abstract:
  In this paper we consider the nonparametric estimation of density and
regression functions with non-negative support using a gamma kernel procedure
introduced by Chen (2000). Strong uniform consistency and asymptotic normality
of the corresponding estimators are established under a general ergodic
assumption on the data generation process. Our results generalize those of Shi
and Song (2016), obtained in the classic i.i.d. framework, and the works of
Bouezmarni and Rombouts (2008, 2010b) and Gospodinov and Hirukawa (2007) for
mixing time series.


title: A Bivariate Copula Additive Model for Location, Scale and Shape

abstract:
  Rigby & Stasinopoulos (2005) introduced generalized additive models for
location, scale and shape (GAMLSS) where the response distribution is not
restricted to belong to the exponential family and its parameters can be
specified as functions of additive predictors that allows for several types of
covariate effects (e.g., linear, non-linear, random and spatial effects). In
many empirical situations, however, modeling simultaneously two or more
responses conditional on some covariates can be of considerable relevance. In
this article, we extend the scope of GAMLSS by introducing a bivariate copula
additive model with continuous margins for location, scale and shape. The
framework permits the copula dependence and marginal distribution parameters to
be estimated simultaneously and, like in GAMLSS, each parameter to be modeled
using an additive predictor. Parameter estimation is achieved within a
penalized likelihood framework using a trust region algorithm with integrated
automatic multiple smoothing parameter selection. The proposed approach allows
for straightforward inclusion of potentially any parametric continuous marginal
distribution and copula function. The models can be easily used via the
copulaReg() function in the R package SemiParBIVProbit. The usefulness of the
proposal is illustrated on two case studies (which use electricity price and
demand data, and birth records) and on simulated data.


title:
A Family of Inexact SQA Methods for Non-Smooth Convex Minimization with
  Provable Convergence Guarantees Based on the Luo-Tseng Error Bound Property

abstract:
  We propose a new family of inexact sequential quadratic approximation (SQA)
methods, which we call the inexact regularized proximal Newton
($\textsf{IRPN}$) method, for minimizing the sum of two closed proper convex
functions, one of which is smooth and the other is possibly non-smooth. Our
proposed method features strong convergence guarantees even when applied to
problems with degenerate solutions while allowing the inner minimization to be
solved inexactly. Specifically, we prove that when the problem possesses the
so-called Luo-Tseng error bound (EB) property, $\textsf{IRPN}$ converges
globally to an optimal solution, and the local convergence rate of the sequence
of iterates generated by $\textsf{IRPN}$ is linear, superlinear, or even
quadratic, depending on the choice of parameters of the algorithm. Prior to
this work, such EB property has been extensively used to establish the linear
convergence of various first-order methods. However, to the best of our
knowledge, this work is the first to use the Luo-Tseng EB property to establish
the superlinear convergence of SQA-type methods for non-smooth convex
minimization. As a consequence of our result, $\textsf{IRPN}$ is capable of
solving regularized regression or classification problems under the
high-dimensional setting with provable convergence guarantees. We compare our
proposed $\textsf{IRPN}$ with several empirically efficient algorithms by
applying them to the $\ell_1$-regularized logistic regression problem.
Experiment results show the competitiveness of our proposed method.


title: Eigenstate Tracking in Open Quantum Systems

abstract:
  Keeping a quantum system in a given instantaneous eigenstate is a control
problem with numerous applications, e.g., in quantum information processing.
The problem is even more challenging in the setting of open quantum systems,
where environment-mediated transitions introduce additional decoherence
channels. Adiabatic passage is a well established solution, but requires a
sufficiently slow evolution time that is dictated by the adiabatic theorem.
Here we develop a systematic projection theory formulation for the
transitionless evolution of general open quantum systems described by
time-local master equations. We derive a time-convolutionless dynamical
equation for the target instantaneous eigenstate of a given time-dependent
Hamiltonian. A transitionless dynamics then arises in terms of a competition
between the average Hamiltonian gap and the decoherence rate, which implies
optimal adiabaticity timescales. We show how eigenstate tracking can be
accomplished via control pulses, without explicitly incorporating
counter-diabatic driving, thus offering an alternative route to shortcuts to
adiabaticity. We examine rectangular pulses, chaotic signals, and white noise,
and find that, remarkably, the effectiveness of eigenstate tracking hardly
depends on the details of the control functions. In all cases the control
protocol keeps the system in the desired instantaneous eigenstate throughout
the entire evolution, along an accelerated adiabatic path.


title: Hijacking Bitcoin: Routing Attacks on Cryptocurrencies

abstract:
  As the most successful cryptocurrency to date, Bitcoin constitutes a target
of choice for attackers. While many attack vectors have already been uncovered,
one important vector has been left out though: attacking the currency via the
Internet routing infrastructure itself. Indeed, by manipulating routing
advertisements (BGP hijacks) or by naturally intercepting traffic, Autonomous
Systems (ASes) can intercept and manipulate a large fraction of Bitcoin
traffic.
  This paper presents the first taxonomy of routing attacks and their impact on
Bitcoin, considering both small-scale attacks, targeting individual nodes, and
large-scale attacks, targeting the network as a whole. While challenging, we
show that two key properties make routing attacks practical: (i) the efficiency
of routing manipulation; and (ii) the significant centralization of Bitcoin in
terms of mining and routing. Specifically, we find that any network attacker
can hijack few (<100) BGP prefixes to isolate ~50% of the mining power---even
when considering that mining pools are heavily multi-homed. We also show that
on-path network attackers can considerably slow down block propagation by
interfering with few key Bitcoin messages.
  We demonstrate the feasibility of each attack against the deployed Bitcoin
software. We also quantify their effectiveness on the current Bitcoin topology
using data collected from a Bitcoin supernode combined with BGP routing data.
  The potential damage to Bitcoin is worrying. By isolating parts of the
network or delaying block propagation, attackers can cause a significant amount
of mining power to be wasted, leading to revenue losses and enabling a wide
range of exploits such as double spending. To prevent such effects in practice,
we provide both short and long-term countermeasures, some of which can be
deployed immediately.


title:
Geodesically Complete Metrics Induce Boundary Non-locality in
  Holography: Consequences for the Entanglement Entropy

abstract:
  We show explicitly that the full structure of IIB string theory is needed to
remove the non-localities that arise in boundary conformal theories that border
hyperbolic spaces on AdS$_5$. Specifically, using the
Caffarelli/Silvestri\cite{caffarelli}, Graham/Zworski\cite{graham}, and
Chang/Gonzalez\cite{chang:2010} extension theorems, we prove that the boundary
operator conjugate to bulk p-forms with negative mass in geodesically complete
metrics is inherently a non-local operator, specifically the fractional
conformal Laplacian. The non-locality, which arises even in compact spaces,
applies to any degree p-form such as a gauge field. We show that the boundary
theory contains fractional derivatives of the longitudinal components of the
gauge field if the gauge field in the bulk along the holographic direction
acquires a mass via the Higgs mechanism. The non-locality is shown to vanish
once the metric becomes incomplete, for example, either 1) asymptotically by
adding N transversely stacked Dd-branes or 2) exactly by giving the boundary a
brane structure and including a single transverse Dd-brane in the bulk. The
original Maldacena conjecture within IIB string theory corresponds to the
former. In either of these proposals, the location of the Dd-branes places an
upper bound on the entanglement entropy because the minimal bulk surface in the
AdS reduction is ill-defined at a brane interface. Since the brane
singularities can be circumvented in the full 10-dimensional spacetime, we
conjecture that the true entanglement entropy must be computed from the minimal
surface in 10-dimensions, which is of course not minimal in the AdS$_5$
reduction.


title:
Multivariate semi-discrete sampling type operators: pointwise
  approximation properties

abstract:
  In this paper multivariate extension of the generalized Durrmeyer sampling
type series are considered. We establish a Voronovskaja type formula and a
quantitative version. Finally some particular examples are discussed.


title: Fermat-like equations that are not partition regular

abstract:
  By means of elementary conditions on coefficients, we isolate a large class
of Fermat-like Diophantine equations that are not partition regular, the
simplest examples being $x^n+y^m=z^k$ with $k\notin\{n,m\}$.


title: On ultradifferentiable functions

abstract:
  We give complete and exact descriptions of spaces of ultradifferentiable
functions that are closed under composition with either holomorphic or
ultradifferentiable functions -- which are two distinct cases. The proof works
by considering formal power series, and stability under differentiation is not
required. As an application of the power series approach we reprove regularity
results for solutions of ode's and pde's without employing tedious estimates
imploying the Fa\`a di Bruno formula for higher derivatives of composite maps.