title: A new progress on Weak Dirac conjecture

abstract:
  In 2014, Payne-Wood proved that every non-collinear set $P$ of $n$ points in
the Euclidean plane contains a point in at least $\dfrac{n}{37}$ lines
determined by $P.$ This is a remarkable answer for the conjecture, which was
proposed by Erd\H{o}s, that every non-collinear set $P$ of $n$ points contains
a point in at least $\dfrac{n}{c_1}$ lines determined by $P$, for some constant
$c_1.$ In this article, we refine the result of Payne-Wood to give that every
non-collinear set $P$ of $n$ points contains a point in at least
$\dfrac{n}{26}+2$ lines determined by $P$ . Moreover, we also discuss some
relations on theorem Beck that every set $P$ of $n$ points with at most $l$
collinear determines at least $\dfrac{1}{61}n(n-l)$ lines.


title: On solution-free sets of integers

abstract:
  Given a linear equation $\mathcal{L}$, a set $A \subseteq [n]$ is
$\mathcal{L}$-free if $A$ does not contain any `non-trivial' solutions to
$\mathcal{L}$. In this paper we consider the following three general questions:
  (i) What is the size of the largest $\mathcal{L}$-free subset of $[n]$?
  (ii) How many $\mathcal{L}$-free subsets of $[n]$ are there?
  (iii) How many maximal $\mathcal{L}$-free subsets of $[n]$ are there?
  We completely resolve (i) in the case when $\mathcal{L}$ is the equation
$px+qy=z$ for fixed $p,q\in \mathbb N$ where $p\geq 2$. Further, up to a
multiplicative constant, we answer (ii) for a wide class of such equations
$\mathcal{L}$, thereby refining a special case of a result of Green. We also
give various bounds on the number of maximal $\mathcal{L}$-free subsets of
$[n]$ for three-variable homogeneous linear equations $\mathcal{L}$. For this,
we make use of container and removal lemmas of Green.


title: Randomised Algorithm for Feature Selection and Classification

abstract:
  We here introduce a novel classification approach adopted from the nonlinear
model identification framework, which jointly addresses the feature selection
and classifier design tasks. The classifier is constructed as a polynomial
expansion of the original attributes and a model structure selection process is
applied to find the relevant terms of the model. The selection method
progressively refines a probability distribution defined on the model structure
space, by extracting sample models from the current distribution and using the
aggregate information obtained from the evaluation of the population of models
to reinforce the probability of extracting the most important terms. To reduce
the initial search space, distance correlation filtering can be applied as a
preprocessing technique. The proposed method is evaluated and compared to other
well-known feature selection and classification methods on standard benchmark
classification problems. The results show the effectiveness of the proposed
method with respect to competitor methods both in terms of classification
accuracy and model complexity. The obtained models have a simple structure,
easily amenable to interpretation and analysis.


title: On the security of the Blockchain Bix Protocol and Certificates

abstract:
  The BIX protocol is a blockchain-based protocol that allows distribution of
certificates linking a subject with his public key, hence providing a service
similar to that of a PKI but without the need of a CA. In this paper we analyze
the security of the BIX protocol in a formal way, in four steps. First, we
identify formal security assumptions which are well-suited to this protocol.
Second, we present some attack scenarios against the BIX protocol. Third, we
provide a formal security proof that some of these attacks are not feasible
under our previously established assumptions. Finally, we show how another
attack may be carried on.


title:
Type I singularities in the curve shortening flow associated to a
  density

abstract:
  We define Type I singularities for the mean curvature flow associated to a
density $\psi$ ($\psi$MCF) and describe the blow-up at singular time of these
singularities. Special attention is paid to the case where the singularity come
from the part of the $\psi$-curvature due to the density. We describe a family
of curves whose evolution under $\psi$MCF (in a Riemannian surface of
non-negative curvature with a density which is singular at a geodesic of the
surface) produces only type I singularities and study the limits of their
blow-ups.


title:
Local existence and uniqueness for the non-resistive MHD equations in
  homogeneous Besov spaces

abstract:
  In the paper, we consider the Cauchy problem of the non-resistive MHD
equations in homogeneous Besov spaces. We prove the local existence and
uniqueness of the solution to the non-resistive MHD equations by using the
iterative scheme and compactness arguments. Our obtained result improves
considerably the recent results in \cite{C,W}.


title:
Optimization approaches to quadrature: new characterizations of Gaussian
  quadrature on the line and quadrature with few nodes on plane algebraic
  curves, on the plane and in higher dimensions

abstract:
  Let $d$ and $k$ be positive integers. Let $\mu$ be a positive Borel measure
on $\mathbb{R}^2$ possessing finite moments up to degree $2d-1$. If the support
of $\mu$ is contained in an algebraic curve of degree $k$, then we show that
there exists a quadrature rule for $\mu$ with at most $dk$ many nodes all
placed on the curve (and positive weights) that is exact on all polynomials of
degree at most $2d-1$. This generalizes both Gauss and (the odd degree case of)
Szeg\H{o} quadrature where the curve is a line and a circle, respectively, to
arbitrary plane algebraic curves. We use this result to show that, without any
hypothesis on the support of $\mu$, there is always a cubature rule for $\mu$
with at most $\frac32d(d-1)+1$ many nodes. In both results, we show that the
quadrature or cubature rule can be chosen such that its value on a certain
positive definite form of degree $2d$ is minimized. We characterize the unique
Gaussian quadrature rule on the line as the one that minimizes this value or
several other values as for example the sum of the nodes' distances to the
origin. The tools we develop should prove useful for obtaining similar results
in higher-dimensional cases although at the present stage we can present only
partial results in that direction.


title:
Simulating the environment around planet-hosting stars - II. Stellar
  winds and inner astrospheres

abstract:
  We present the results of a comprehensive numerical simulation of the
environment around three exoplanet-host stars (HD 1237, HD 22049, and HD
147513). Our simulations consider one of the latest models currently used for
space weather studies in the Heliosphere. Large-scale magnetic field maps,
recovered with two implementations of the tomographic technique of
Zeeman-Doppler imaging, serve to drive steady-state solutions in each system.
This paper contains the description of the stellar wind and inner astrosphere,
while the coronal structure was previously discussed in Alvarado-G\'omez et al.
(2016). The analysis includes the magneto-hydrodynamical properties of the
stellar wind, the associated mass and angular momentum loss rates, as well as
the topology of the astrospheric current sheet in each system. A systematic
comparison among the considered cases is performed, including two reference
solar simulations covering activity minimum and maximum. For HD 1237, we
investigate the interactions between the structure of the developed stellar
wind, and a possible magnetosphere around the Jupiter-mass planet in this
system. We find that the process of particle injection into the planetary
atmosphere is dominated by the density distribution rather than velocity
profile of the stellar wind. In this context, we predict a maximum exoplanetary
radio emission of 12 mJy at 40 MHz in this system, assuming the crossing of a
high-density streamer during periastron passage. Furthermore, in combination
with the analysis performed in Alvarado-G\'omez et al. (2016), we obtain for
the first time a fully simulated mass loss-activity relation, which is compared
and discussed in the context of the relation based on astrospheric detections
proposed by Wood et al. (2005a). Finally, we provide a characterisation of the
3D properties of the stellar wind of these systems, at the inner edges of their
habitable zones.


title: An Investment Model with Switching Costs and the Option to Abandon

abstract:
  We develop a complete analysis of a general entry-exit-scrapping model. In
particular, we consider an investment project that operates within a random
environment and yields a payoff rate that is a function of a stochastic
economic indicator such as the price of or the demand for the project's output
commodity. We assume that the investment project can operate in two modes, an
"open" one and a "closed" one. The transitions from one operating mode to the
other one are costly and immediate, and form a sequence of decisions made by
the project's management. We also assume that the project can be permanently
abandoned at a discretionary time and at a constant sunk cost. The objective of
the project's management is to maximise the expected discounted payoff
resulting from the project's management over all switching and abandonment
strategies. We derive the explicit solution to this stochastic control problem
that involves impulse control as well as discretionary stopping. It turns out
that this has a rather rich structure and the optimal strategy can take eight
qualitatively different forms, depending on the problems data.


title:
Stabilization and frequency control of a DFB laser with a tunable
  optical reflector integrated in a Silicon Photonics PIC

abstract:
  We investigate the effect of tunable optical feedback on a commercial DFB
laser edge coupled to a Silicon Photonics planar integrated circuit in which a
tunable reflector has been implemented by means of a ring resonator based
add-drop multiplexer. Controlled optical feedback allows for fine-tuning of the
laser oscillation frequency. Under certain conditions it also allows
suppression of bifurcation modes triggered by reflections occurring elsewhere
on the chip. A semi-analytical model describing laser dynamics under combined
optical feedback from the input facet of the edge coupler and from the tunable
on-chip reflector fits the measurements. Compensation of detrimental effects
from reflections induced elsewhere on a transceiver chip may allow moving
isolators downstream in future communications systems, facilitating direct
hybrid laser integration in Silicon Photonics chips, provided a suitable
feedback signal for a control system can be identified. Moreover, the optical
frequency tuning at lower feedback levels can be used to form a rapidly tunable
optical oscillator as part of an optical phase locked loop, circumventing the
problem of the thermal to free carrier effect crossover in the FM response of
injection current controlled semiconductor laser diodes.


title:
Integrability study of a four-dimensional eighth-order nonlinear wave
  equation

abstract:
  We study the integrability of the four-dimensional eighth-order nonlinear
wave equation of Kac and Wakimoto, associated with the exceptional affine Lie
algebra ${\mathfrak e}_6^{(1)}$. Using the Painlev\'{e} analysis for partial
differential equations, we show that this equation must be non-integrable in
the Lax sense but very likely it possesses a lower-order integrable reduction.


title: Stochastic chaos in a turbulent swirling flow

abstract:
  We report the experimental evidence of the existence of a random attractor in
a fully developed turbulent swirling flow. By defining a global observable
which tracks the asymmetry in the flux of angular momentum imparted to the
flow, we can first reconstruct the associated turbulent attractor and then
follow its route towards chaos. We further show that the experimental attractor
can be modeled by stochastic Duffing equations, that match the quantitative
properties of the experimental flow, namely the number of quasi-stationary
states and transition rates among them, the effective dimensions, and the
continuity of the first Lyapunov exponents. Such properties can neither be
recovered using deterministic models nor using stochastic differential
equations based on effective potentials obtained by inverting the probability
distributions of the experimental global observables. Our findings open the way
to low dimensional modeling of systems featuring a large number of degrees of
freedom and multiple quasi-stationary states.


title:
Photoemission Spectra from Reduced Density Matrices: the Band Gap in
  Strongly Correlated Systems

abstract:
  We present a method for the calculation of photoemission spectra in terms of
reduced density matrices. We start from the spectral representation of the
one-body Green's function G, whose imaginary part is related to photoemission
spectra, and we introduce a frequency-dependent effective energy that accounts
for all the poles of G. Simple approximations to this effective energy give
accurate spectra in model systems in the weak as well as strong correlation
regime. In real systems reduced density matrices can be obtained from reduced
density-matrix functional theory. Here we use this approach to calculate the
photoemission spectrum of bulk NiO: our method yields a qualitatively correct
picture both in the antiferromagnetic and paramagnetic phases, contrary to
mean-field methods, in which the paramagnet is a metal.


title:
Different approaches to generate matching effects using arrays in
  contact with superconducting films

abstract:
  Superconducting films in contact with non-superconducting regular arrays can
exhibit commensurability effects between the vortex lattice and the unit cell
of the pinning array. These matching effects yield a slowdown of the vortex
flow and the corresponding dissipation decrease. The superconducting samples
are Nb films grown on Si substrates. We have studied these matching effects
with the array on top, embedded or threading the Nb superconducting films and
using different materials (Si, Cu, Ni, Py dots and dots fabricated with Co/Pd
multilayers). These hybrids allow studying the contribution of different
pinning potentials to the matching effects. The main findings are: i) Periodic
roughness induced in the superconducting film is enough to generate resistivity
minima; ii) A minor effect is achieved by magnetic pinning from periodic
magnetic field potentials obtained by dots with out of plane magnetization
grown on top of the superconducting film, iii) In the case of array of magnetic
dots embedded in the films vortex flow probes the magnetic state; i.e.
magnetoresistance measurements detect the magnetic state of very small
nanomagnets. In addition, we have studied the role played by the local order in
the commensurability effects. This was attained using an array that mimics a
smectic crystal. We have found that preserving the local order is crucial. If
the local order is not retained the magnetoresistance minima vanish.


title: KIC011764567: An evolved object showing substantial flare-activity

abstract:
  We intensively studied the flare activity on the stellar object KIC011764567.
The star was thought to be solar type, with a temperature of $T_{eff} = (5640
\pm 200)\,$K, $\log(g) = (4.3 \pm 0.3)\,$dex and a rotational period of Prot 22
d (Brown et al. 2011). High resolution spectra turn the target to an evolved
object with Teff = (5300 \pm 150) K, a metalicity of $[m/H] = (-0.5 \pm 0.2)$,
a surface gravity of $log(g) = (3.3 \pm 0.4)\,$dex, and a projected rotational
velocity of $v sin i = (22 \pm 1)\,kms^{-1}$. Within an observing time span of
4 years we detected 150 flares in Kepler data in an energy range of $10^{36} -
10^{37}$ erg. From a dynamical Lomb-Scargle periodogram we have evidence for
differential rotation as well as for stellar spot evolution and migration.
Analysing the occurrence times of the flares we found hints for a periodic
flare frequency cycle of $430 - 460 $d, the significance increases with an
increasing threshold of the flares equivalent duration. One explanation is a
very short activity cycle of the star with that period. Another possibility,
also proposed by others in similar cases, is that the larger flares may be
triggered by external phenomena, such as magnetically interaction with an
unseen companion. Our high resolution spectra show that KIC011764567 is not a
short period binary star.


abstract:
  In this paper we study the Heisenberg uniqueness pairs corresponding to
finite number of parallel lines $\Gamma$. We give a necessary condition and a
sufficient condition for a subset $\Lambda$ of $\R$ so that $(\Gamma,\Lambda)$
becomes a HUP.


title: SEMBED: Semantic Embedding of Egocentric Action Videos

abstract:
  We present SEMBED, an approach for embedding an egocentric object interaction
video in a semantic-visual graph to estimate the probability distribution over
its potential semantic labels. When object interactions are annotated using
unbounded choice of verbs, we embrace the wealth and ambiguity of these labels
by capturing the semantic relationships as well as the visual similarities over
motion and appearance features. We show how SEMBED can interpret a challenging
dataset of 1225 freely annotated egocentric videos, outperforming SVM
classification by more than 5%.


title: Koml\'os's tiling theorem via graphon covers

abstract:
  Komlos [Komlos: Tiling Turan Theorems, Combinatorica, 2000] determined the
asymptotically optimal minimum-degree condition for covering a given proportion
of vertices of a host graph by vertex-disjoint copies of a fixed graph H, thus
essentially extending the Hajnal-Szemeredi theorem which deals with the case
when H is a clique. We give a proof of a graphon version of Komlos's theorem.
To prove this graphon version, and also to deduce from it the original
statement about finite graphs, we use the machinery introduced in [Hladky, Hu,
Piguet: Tilings in graphons, arXiv:1606.03113]. We further prove a stability
version of Komlos's theorem.


title:
Effective penetration length and interstitial vortex pinning in
  superconducting films with regular arrays of defects

abstract:
  In order to compare magnetic and non-magnetic pinning we have nanostructured
two superconducting films with regular arrays of pinning centers: Cu
(non-magnetic) dots in one case, and Py (magnetic) dots in the other. For low
applied magnetic fields, when all the vortices are pinned in the artificial
inclusions, magnetic dots prove to be better pinning centers, as has been
generally accepted. Unexpectedly, when the magnetic field is increased and
interstitial vortices appear, the results are very different: we show how the
stray field generated by the magnetic dots can produce an effective reduction
of the penetration length. This results in strong consequences in the transport
properties, which, depending on the dot separation, can lead to an enhancement
or worsening of the transport characteristics. Therefore, the election of the
magnetic or non-magnetic character of the pinning sites for an effective
reduction of dissipation will depend on the range of the applied magnetic
field.


title:
Wavelet-based filter methods to detect small transiting planets in
  stellar light curves

abstract:
  Strong variations of any kind and causes within a stellar light curve may
prohibit the detection of transits, particularly of faint or shallow transits
caused by small planets passing in front of the stellar disk. The success of
future space telescopes with the goal for finding small planets will be based
on proper filtering, analysis and detection of transits in perturbed stellar
light curves. The wavelet-based filter methods VARLET and PHALET, developed by
RIU-PF, in combination with the transit detection software package EXOTRANS
allow the extraction of (i) strong stellar variations, (ii) instrument caused
spikes and singularities within a stellar light curve, (iii) already detected
planetary or stellar binary transits in order to be able to search for further
planets or planets about binary stars. Once the light curve is filtered,
EXOTRANS is able to search efficiently, effectively and precisely for transits,
in particular for faint transits.


title: On powers that are sums of consecutive like powers

abstract:
  Let $k \ge 2$ be even, and let $r$ be a non-zero integer. We show that for
almost all $d \ge 2$ (in the sense of natural density), the equation $$
x^k+(x+r)^k+\cdots+(x+(d-1)r)^k=y^n, \qquad x,~y,~n \in \mathbb{Z}, \qquad n
\ge 2, $$ has no solutions.


title: The Stabilizer of Elementary Symmetric Polynomials

abstract:
  We study the r-th elementary symmetric polynomial in $n$ variables with
2<r<n. There are two kinds of linear transformations on the parameter space
that leave this polynomial invariant: Namely, any permutation of the variables
and simultaneous scaling by any r-th root of unity. We prove that there are no
other linear transformations with this property.


title:
High-order implicit Galerkin-Legendre spectral method for the
  two-dimensional Schrodinger equation

abstract:
  In this paper, we propose Galerkin-Legendre spectral method with implicit
Runge-Kutta method for solving the unsteady two-dimensional Schrodinger
equation with nonhomogeneous Dirichlet boundary conditions and initial
condition. We apply a Galerkin-Legendre spectral method for discretizing
spatial derivatives, and then employ the implicit Runge-Kutta method for the
time integration of the resulting linear first-order system of ordinary
differential equations in complex domain. We derive the spectral rate of
convergence for the proposed method in the L^2-norm for the semidiscrete
formulation.
  Numerical experiments show our formulation have high-order accurate, and have
the exponential rates of convergence in space.


title: Stereo Video Deblurring

abstract:
  Videos acquired in low-light conditions often exhibit motion blur, which
depends on the motion of the objects relative to the camera. This is not only
visually unpleasing, but can hamper further processing. With this paper we are
the first to show how the availability of stereo video can aid the challenging
video deblurring task. We leverage 3D scene flow, which can be estimated
robustly even under adverse conditions. We go beyond simply determining the
object motion in two ways: First, we show how a piecewise rigid 3D scene flow
representation allows to induce accurate blur kernels via local homographies.
Second, we exploit the estimated motion boundaries of the 3D scene flow to
mitigate ringing artifacts using an iterative weighting scheme. Being aware of
3D object motion, our approach can deal robustly with an arbitrary number of
independently moving objects. We demonstrate its benefit over state-of-the-art
video deblurring using quantitative and qualitative experiments on rendered
scenes and real videos.


title: Topological orders and factorization homology

abstract:
  In the study of 2d (the space dimension) topological orders, it is well-known
that bulk excitations are classified by unitary modular tensor categories. But
these categories only describe the local observables on an open 2-disk in the
long wave length limit. For example, the notion of braiding only makes sense
locally. It is natural to ask how to obtain global observables on a closed
surface. The answer is provided by the theory of factorization homology. We
compute the factorization homology of a closed surface $\Sigma$ with the
coefficient given by a unitary modular tensor category, and show that the
result is given by a pair $(\mathbf{H}, u_\Sigma)$, where $\mathbf{H}$ is the
category of finite-dimensional Hilbert spaces and $u_\Sigma\in \mathbf{H}$ is a
distinguished object that coincides precisely with the Hilbert space assigned
to the surface $\Sigma$ in Reshetikhin-Turaev TQFT. We also generalize this
result to a closed stratified surface decorated by anomaly-free topological
defects of codimension 0,1,2. This amounts to compute the factorization
homology of a stratified surface with a coefficient system satisfying an
anomaly-free condition.


title:
The evolution to localized and front solutions in a non-Lipschitz
  reaction-diffusion Cauchy problem with trivial initial data

abstract:
  In this paper, we establish the existence of spatially inhomogeneous
classical self-similar solutions to a non-Lipschitz semi-linear parabolic
Cauchy problem with trivial initial data. Specifically we consider bounded
solutions to an associated two-dimensional non-Lipschitz non-autonomous
dynamical system, for which, we establish the existence of a two-parameter
family of homoclinic connections on the origin, and a heteroclinic connection
between two equilibrium points. Additionally, we obtain bounds and estimates on
the rate of convergence of the homoclinic connections to the origin.


title: Performance estimates for spectrographs using photonic reformatters

abstract:
  Using a photonic reformatter to eliminate the effects of conventional modal
noise could greatly improve the stability of a high resolution spectrograph.
However the regimes where this advantage becomes clear are not yet defined.
Here we will look at where modal noise becomes a problem in conventional high
resolution spectroscopy and what impact photonic spectrographs could have. We
will theoretically derive achievable radial velocity measurements to compare
photonic instruments and conventional ones. We will discuss the theoretical and
experimental investigations that will need to be undertaken to optimize and
prove the photonic reformatting concept.


title:
From a thin film model for passive suspensions towards the description
  of osmotic biofilm spreading

abstract:
  Biofilms are ubiquitous macro-colonies of bacteria that develop at various
interfaces (solid-liquid, solid-gas or liquid-gas). The formation of biofilms
starts with the attachment of individual bacteria to an interface, where they
proliferate and produce a slimy polymeric matrix - two processes that result in
colony growth and spreading. Recent experiments on the growth of biofilms on
agar substrates under air have shown that for certain bacterial strains, the
production of the extracellular matrix and the resulting osmotic influx of
nutrient-rich water from the agar into the biofilm are more crucial for the
spreading behaviour of a biofilm than the motility of individual bacteria. We
present a model which describes the biofilm evolution and the advancing biofilm
edge for this spreading mechanism. The model is based on a gradient dynamics
formulation for thin films of biologically passive liquid mixtures and
suspensions, supplemented by bioactive processes which play a decisive role in
the osmotic spreading of biofilms. It explicitly includes the wetting
properties of the biofilm on the agar substrate via a disjoining pressure and
can therefore give insight into the interplay between passive surface forces
and bioactive growth processes.


title:
A trilinear approach to square function and local smoothing estimates
  for the wave operator

abstract:
  The purpose of this paper is to improve the known estimates for Mockenhaupt's
square function in $\mathbb R^3$ and for Sogge's local smoothing in $\mathbb
R^{2+1}$ spacetime. For this we use the trilinear approach of S. Lee and A.
Vargas for the cone multiplier with some trilinear estimates obtained from the
$\ell^2$ decoupling theorem and multilinear restriction theorem.


title:
Gyroscope precession along bound equatorial plane orbits around a Kerr
  black hole

abstract:
  The precession of a test gyroscope along stable bound equatorial plane orbits
around a Kerr black hole is analyzed and the precession angular velocity of the
gyro's parallel transported spin vector and the increment in precession angle
after one orbital period is evaluated. The parallel transported Marck frame
which enters this discussion is shown to have an elegant geometrical
explanation in terms of the electric and magnetic parts of the Killing-Yano
2-form and a Wigner rotation effect.


title:
The number of catenoids connecting two coaxial circles in
  Lorentz-Minkowski space

abstract:
  In 3-dimensional Lorentz-Minkowski space we determine the number of catenoids
connecting two coaxial circles in parallel planes. This study is separated
according to the types of circles and the causal character (spacelike and
timelike) of the catenoid.


title: Dimension theory of the moduli space of twisted $k$-differentials

abstract:
  In this note we extend the dimension theory for the spaces
$\widetilde{\mathcal H}_g^k(\mu)$ of twisted $k$-differentials defined by
Farkas and Pandharipande in [FP15] to the case $k>1$. In particular, we show
that the intersection $\widetilde{\mathcal H}_g^k(\mu) \cap \mathcal{M}_{g,n}$
is a union of smooth components of the expected dimensions for all $k\geq 0$.
We also extend a conjectural formula from [FP15] for a weighted fundamental
class of $\widetilde{\mathcal H}_g^k(\mu)$ and provide evidence in low genus.


title:
Measurement of the $b\overline{b}$ dijet cross section in $pp$
  collisions at $\sqrt{s} = 7$ TeV with the ATLAS detector

abstract:
  The dijet production cross section for jets containing a $b$-hadron
($b$-jets) has been measured in proton-proton collisions with a centre-of-mass
energy of $\sqrt{s} = 7$ TeV, using the ATLAS detector at the LHC. The data
used correspond to an integrated luminosity of 4.2 fb$^{-1}$. The cross section
is measured for events with two identified $b$-jets with a transverse momentum
$p_T > 20$ GeV and a minimum separation in the $\eta$-$\phi$ plane of $\Delta R
= 0.4$. At least one of the jets in the event is required to have $p_T > 270$
GeV. The cross section is measured differentially as a function of dijet
invariant mass, dijet transverse momentum, boost of the dijet system, and the
rapidity difference, azimuthal angle and angular distance between the $b$-jets.
The results are compared to different predictions of leading order and
next-to-leading order perturbative quantum chromodynamics matrix elements
supplemented with models for parton-showers and hadronization.


title: Waves of DNA: Propagating Excitations in Extended Nanoconfined Polymers

abstract:
  We use a nanofluidic system to investigate the emergence of thermally driven
collective phenomena along a single polymer chain. In our approach, a single
DNA molecule is confined in a nanofluidic slit etched with arrays of embedded
nanocavities; the cavity lattice is designed so that a single chain occupies
multiple cavities. Fluorescent video-microscopy data shows that waves of excess
fluorescence propagate across the cavity-straddling molecule, corresponding to
propagating fluctuations of contour overdensity in the cavities. The waves are
quantified by examining the correlation in intensity fluctuations between
neighbouring cavities. Correlations grow from an anti-correlated minimum to a
correlated maximum before decaying, corresponding to a transfer of contour
between neighbouring cavities at a fixed transfer time-scale. The observed
dynamics can be modelled using Langevin dynamics simulations and a minimal
lattice model of coupled diffusion. This study shows how confinement-based
sculpting of the polymer equilibrium configuration, by renormalizing the
physical system into a series of discrete cavity states, can lead to new types
of dynamic collective phenomena.


title:
Interplay of Infrared Divergences and Gauge-Dependence of the Effective
  Potential

abstract:
  The perturbative effective potential suffers infrared (IR) divergences in
gauges with massless Goldstones in their minima (like Landau or Fermi gauges)
but the problem can be fixed by a suitable resummation of the Goldstone
propagators. When the potential minimum is generated radiatively,
gauge-independence of the potential at the minimum also requires resummation
and we demonstrate that the resummation that solves the IR problem also cures
the gauge-dependence issue, showing this explicitly in the Abelian Higgs model
in Fermi gauge. In the process we find an IR divergence (in the location of the
minimum) specific to Fermi gauge and not appreciated in recent literature. We
show that physical observables can still be computed in this gauge and we
further show how to get rid of this divergence by a field redefinition. All
these results generalize to the Standard Model case.


title: An Optimized Huffmans Coding by the method of Grouping

abstract:
  Data compression has become a necessity not only the in the field of
communication but also in various scientific experiments. The data that is
being received is more and the processing time required has also become more. A
significant change in the algorithms will help to optimize the processing
speed. With the invention of Technologies like IoT and in technologies like
Machine Learning there is a need to compress data. For example training an
Artificial Neural Network requires a lot of data that should be processed and
trained in small interval of time for which compression will be very helpful.
There is a need to process the data faster and quicker. In this paper we
present a method that reduces the data size. This method is known as Optimized
Huffmans Coding. In the Huffmans coding we encode the messages so as to reduce
the data and here in the optimized Huffmans coding we compress the data to a
great extent which helps in various signal processing algorithms and has
advantages in many applications. Here in this paper we have presented the
Optimized Huffmans Coding method for Text compression. This method but has
advantages over the normal Huffmans coding. This algorithm presented here says
that every letter can be grouped together and encoded which not only reduces
the size but also the Huffmans Tree data that is required for decoding, hence
reducing the data size. This method has huge scientific applications.


title:
Video Registration in Egocentric Vision under Day and Night Illumination
  Changes

abstract:
  With the spread of wearable devices and head mounted cameras, a wide range of
application requiring precise user localization is now possible. In this paper
we propose to treat the problem of obtaining the user position with respect to
a known environment as a video registration problem. Video registration, i.e.
the task of aligning an input video sequence to a pre-built 3D model, relies on
a matching process of local keypoints extracted on the query sequence to a 3D
point cloud. The overall registration performance is strictly tied to the
actual quality of this 2D-3D matching, and can degrade if environmental
conditions such as steep changes in lighting like the ones between day and
night occur. To effectively register an egocentric video sequence under these
conditions, we propose to tackle the source of the problem: the matching
process. To overcome the shortcomings of standard matching techniques, we
introduce a novel embedding space that allows us to obtain robust matches by
jointly taking into account local descriptors, their spatial arrangement and
their temporal robustness. The proposal is evaluated using unconstrained
egocentric video sequences both in terms of matching quality and resulting
registration performance using different 3D models of historical landmarks. The
results show that the proposed method can outperform state of the art
registration algorithms, in particular when dealing with the challenges of
night and day sequences.


title: On the generalized associativity equation

abstract:
  The so-called generalized associativity functional equation G(J(x,y),z) =
H(x,K(y,z)) has been investigated under various assumptions, for instance when
the unknown functions G, H, J, and K are real, continuous, and strictly
monotonic in each variable. In this note we investigate the following related
problem: given the functions J and K, find every function F that can be written
in the form F(x,y,z) = G(J(x,y),z) = H(x,K(y,z)) for some functions G and H. We
show how this problem can be solved when any of the inner functions J and K has
the same range as one of its sections.


title:
Single-particle and collective motion in unbound deformed $
  ^{39}\text{Mg} $

abstract:
  Background: Deformed neutron-rich magnesium isotopes constitute a fascinating
territory where the interplay between collective rotation and single-particle
motion is strongly affected by the neutron continuum. The unbound $fp$-shell
nucleus $ ^{39}\text{Mg} $ is an ideal candidate to study this interplay.
Purpose: In this work, we predict the properties of low-lying resonant states
of $ ^{39}\text{Mg} $, using a suite of realistic theoretical approaches rooted
in the open quantum system framework. Method: To describe the spectrum and
decay modes of $ ^{39}\text{Mg} $ we use the conventional Shell Model, Gamow
Shell Model, Resonating Group Method, Density Matrix Renormalization Group
method, and the non-adiabatic Particle-Plus-Rotor model formulated in the
Berggren basis. Results: The unbound ground state of $ ^{39}\text{Mg} $ is
predicted to be either a $ J^{\pi} = {7/2}^- $ state or a $ {3/2}^- $ state. A
narrow $ J^{\pi} = {7/2}^- $ ground-state candidate exhibits a resonant
structure reminiscent of that of its one-neutron halo neighbor $ ^{37}\text{Mg}
$, which is dominated by the $ f_{7/2} $ partial wave at short distances and a
$ p_{3/2} $ component at large distances. A $ J^{\pi}={3/2}^- $ ground-state
candidate is favored by the large deformation of the system. It can be
associated with the $ {1/2}^- [321] $ Nilsson orbital dominated by the $\ell=1$
wave; hence its predicted width is large. The excited $J^{\pi} = {1/2}^-$ and
$5/2^-$ states are expected to be broad resonances, while the $ J^{\pi} =
{9/2}^- $ and $ {11/2}^- $ members of the ground-state rotational band are
predicted to have very small neutron decay widths. Conclusion: We demonstrate
that the subtle interplay between deformation, shell structure, and continuum
coupling can result in a variety of excitations in an unbound nucleus just
outside the neutron drip line.


title: Towards Fulton's conjecture

abstract:
  We present an alternate proof, much quicker and more straightforward than the
original one, of a celebrated Fulton's conjecture on the ample cone of the
moduli space of stable rational curves with n marked points in the case n=7.


title: Faceless Person Recognition; Privacy Implications in Social Media

abstract:
  As we shift more of our lives into the virtual domain, the volume of data
shared on the web keeps increasing and presents a threat to our privacy. This
works contributes to the understanding of privacy implications of such data
sharing by analysing how well people are recognisable in social media data. To
facilitate a systematic study we define a number of scenarios considering
factors such as how many heads of a person are tagged and if those heads are
obfuscated or not. We propose a robust person recognition system that can
handle large variations in pose and clothing, and can be trained with few
training samples. Our results indicate that a handful of images is enough to
threaten users' privacy, even in the presence of obfuscation. We show detailed
experimental results, and discuss their implications.


title:
Nonlinear currents in a ring-shaped waveguide with balanced gain and
  dissipation

abstract:
  We describe linear and nonlinear modes in a ring-shaped waveguide with
localized gain and dissipation modeled by two Dirac $\delta$ functions located
symmetrically. The strengths of the gain and dissipation are equal, i.e., the
system obeys the parity-time symmetry. This configuration describes atomic
Bose-Einstein condensates with local loading and local elimination of atoms,
polaritonic condensates, or optical ring resonators with local pump and
absorption. We discuss the linear spectrum of such a system and show if the
location of the $\delta$ functions is slightly asymmetric, then the system can
be driven through a series of exceptional points by the change of the
gain-and-loss coefficient. In the nonlinear case, the system admits solutions
with spatially constant and periodic densities which are presented in the exact
analytical form. These solutions are supported by the current directed from the
gain potential towards the absorbing potential. The system also admits
currentless solutions. Stability and bifurcations of nonlinear solutions are
also described.


title:
A stability criterion for non-degenerate equilibrium states of
  completely integrable systems

abstract:
  We provide a criterion in order to decide the stability of non-degenerate
equilibrium states of completely integrable systems. More precisely, given a
Hamilton-Poisson realization of a completely integrable system generated by a
smooth $n-$ dimensional vector field, $X$, and a non-degenerate regular (in the
Poisson sense) equilibrium state, $\overline{x}_e$, we define a scalar
quantity, $\mathcal{I}_{X}(\overline{x}_e)$, whose sign determines the
stability of the equilibrium. Moreover, if $\mathcal{I}_{X}(\overline{x}_e)>0$,
then around $\overline{x}_e$ there exist one-parameter families of periodic
orbits shrinking to $\{\overline{x}_e \}$, whose periods approach
$2\pi/\sqrt{\mathcal{I}_{X}(\overline{x}_e)}$ as the parameter goes to zero.
The theoretical results are illustrated in the case of the Rikitake dynamical
system.


title:
Exponential Stability and Stabilization of Extended Linearizations via
  Continuous Updates of Riccati Based Feedback

abstract:
  Many recent works on stabilization of nonlinear systems target the case of
locally stabilizing an unstable steady state solutions against small
perturbation. In this work we explicitly address the goal of driving a system
into a nonattractive steady state starting from a well developed state for
which the linearization based local approaches will not work. Considering
extended linearizations or state-dependent coefficient representations of
nonlinear systems, we develop sufficient conditions for stability of solution
trajectories. We find that if the coefficient matrix is uniformly stable in a
sufficiently large neighborhood of the current state, then the state will
eventually decay. Based on these analytical results we propose an update scheme
that is designed to maintain the stabilization property of Riccati based
feedback constant during a certain period of the state evolution. We illustrate
the general applicability of the resulting algorithm for setpoint stabilization
of nonlinear autonomous systems and its numerical efficiency in two examples.


title: Three Dimensional Reductions of Four-Dimensional Quasilinear Systems

abstract:
  In this paper we show that integrable four dimensional linearly degenerate
equations of second order possess infinitely many three dimensional
hydrodynamic reductions. Furthermore, they are equipped infinitely many
conservation laws and higher commuting flows. We show that the dispersionless
limits of nonlocal KdV and nonlocal NLS equations (the so-called Breaking
Soliton equations introduced by O.I. Bogoyavlenski) are one and two component
reductions (respectively) of one of these four dimensional linearly degenerate
equations.


title:
Transient Analysis of a Resource-limited Recovery Policy for Epidemics:
  a Retrial Queueing Approach

abstract:
  Knowledge on the dynamics of standard epidemic models and their variants over
complex networks has been well-established primarily in the stationary regime,
with relatively little light shed on their transient behavior. In this paper,
we analyze the transient characteristics of the classical susceptible-infected
(SI) process with a recovery policy modeled as a state-dependent retrial
queueing system in which arriving infected nodes, upon finding all the limited
number of recovery units busy, join a virtual buffer and try persistently for
service in order to regain susceptibility. In particular, we formulate the
stochastic SI epidemic model with added retrial phenomenon as a finite
continuous-time Markov chain (CTMC) and derive the Laplace transforms of the
underlying transient state probability distributions and corresponding moments
for a closed population of size $N$ driven by homogeneous and heterogeneous
contacts. Our numerical results reveal the strong influence of infection
heterogeneity and retrial frequency on the transient behavior of the model for
various performance measures.


title:
Cytomegalovirus Antigenic Mimicry of Human Alloreactive Peptides: A
  Potential Trigger for Graft versus Host Disease

abstract:
  The association between human cytomegalovirus (hCMV) reactivation and the
development of graft-versus-host-disease (GVHD) has been observed in stem cell
transplantation (SCT). Seventy seven SCT donor-recipient pairs (DRP) (HLA
matched unrelated donor (MUD), n=50; matched related donor (MRD), n=27)
underwent whole exome sequencing to identify single nucleotide polymorphisms
(SNPs) generating alloreactive peptide libraries for each DRP (9-mer
peptide-HLA complexes); Human CMV CROSS (Cross-Reactive Open Source Sequence)
Database was compiled from NCBI; HLA class I binding affinity for each DRPs HLA
was calculated by NetMHCpan 2.8 and hCMV- derived 9-mers algorithmically
compared to the alloreactive peptide-HLA complex libraries. Short consecutive
(6 or greater) amino acid (AA) sequence homology matching hCMV to recipient
peptides was considered for HLA-bound-peptide (IC50<500 nM) cross reactivity.
Of the 70,686 hCMV 9-mers contained within the hCMV CROSS database, 29,658.8
+/- 9038.5 were found to match MRD DRP alloreactive peptides and 52,910.2 +/-
16121.8 matched MUD DRP peptides (Student's T-test, p<0.001). In silico
analysis revealed multiple high affinity, immunogenic CMV-Human peptide matches
(IC50<500 nM) expressed in GVHD-affected tissue-specific manner (proteins
expressed at 10 RPKM or greater). hCMV+GVHD was found in 18 patients, 13
developing hCMV viremia before GVHD onset with a subset analysis of 7 instances
of hCMV viremia prior to acute GVHD onset (n=3), chronic GVHD (n=2) and acute +
chronic GVHD (n=2) indicating cross reactive peptide expression within affected
organs. We propose that based on our analysis and preliminary clinical
correlations that hCMV immune cross-reactivity may cause antigenic mimicry of
human alloreactive peptides triggering GVHD.


title:
On the Perturbation-Iteration Algorithm for System of Fractional
  Differential Equations

abstract:
  In this study, perturbation-iteration algorithm, namely PIA, is applied to
solve some types of system of fractional differential equations (FDEs) for the
first time. To illustrate the efficiency of the method, numerical solutions are
compared with the results published in the literature by considering some FDEs.
The results confirm that the PIA is powerful, simple and reliable method for
solving system of nonlinear fractional differential equations.


title: Topological insulating phases from two-dimensional nodal loop semimetals

abstract:
  Starting from a minimal model for a 2D nodal loop semimetal, we study the
effect of chiral mass gap terms. The resulting Dirac loop anomalous Hall
insulator's Chern number is the phase winding number of the mass gap terms on
the loop. We provide simple lattice models, analyze the topological phases and
generalize a previous index characterizing topological transitions. The
responses of the Dirac loop anomalous Hall and quantum spin Hall insulators to
a magnetic field's vector potential are also studied both in weak and strong
field regimes, as well as the edge states in a ribbon geometry.


title:
Momentum distribution of liquid 4He across the normal-superfluid phase
  transition

abstract:
  We have carried out a study of the momentum distribution and of the spectrum
of elementary excitations of liquid $^4$He across the normal-superfluid
transition temperature, using the path integral Monte Carlo method. Our results
for the momentum distribution in the superfluid regime show that a kink is
present in the range of momenta corresponding to the roton excitation. This
effect disappears when crossing the transition temperature to the normal fluid,
in a behavior currently unexplained by theory.


title: Test of Lorentz Violation with Astrophysical Neutrino Flavor

abstract:
  The high-energy astrophysical neutrinos recently discovered by IceCube opened
a new way to test Lorentz and CPT violation through the astrophysical neutrino
mixing properties. The flavor ratio of astrophysical neutrinos is a very
powerful tool to investigate tiny effects caused by Lorentz and CPT violation.
There are 3 main findings; (1) current limits on Lorentz and CPT violation in
neutrino sector are not tight and they allow for any flavor ratios, (2)
however, the observable flavor ratio on the Earth is tied with the flavor ratio
at production, this means we can test both the presence of new physics and the
astrophysical neutrino production mechanism simultaneously, and (3) the
astrophysical neutrino flavor ratio is one of the most stringent tests of
Lorentz and CPT violation.


title: An Efficient Representation for Filtrations of Simplicial Complexes

abstract:
  A filtration over a simplicial complex $K$ is an ordering of the simplices of
$K$ such that all prefixes in the ordering are subcomplexes of $K$. Filtrations
are at the core of Persistent Homology, a major tool in Topological Data
Analysis. In order to represent the filtration of a simplicial complex, the
entire filtration can be appended to any data structure that explicitly stores
all the simplices of the complex such as the Hasse diagram or the recently
introduced Simplex Tree [Algorithmica '14]. However, with the popularity of
various computational methods that need to handle simplicial complexes, and
with the rapidly increasing size of the complexes, the task of finding a
compact data structure that can still support efficient queries is of great
interest.
  In this paper, we propose a new data structure called the Critical Simplex
Diagram (CSD) which is a variant of the Simplex Array List (SAL) [Algorithmica
'17]. Our data structure allows one to store in a compact way the filtration of
a simplicial complex, and allows for the efficient implementation of a large
range of basic operations. Moreover, we prove that our data structure is
essentially optimal with respect to the requisite storage space. Finally, we
show that the CSD representation admits fast construction algorithms for Flag
complexes and relaxed Delaunay complexes.


title:
Overlay Secondary Spectrum Sharing with Independent Re-attempts in
  Cognitive Radios

abstract:
  Opportunistic spectrum access (OSA) is a promising reform paradigm envisioned
to address the issue of spectrum scarcity in cognitive radio networks (CRNs).
While current models consider various aspects of the OSA scheme, the impact of
retrial phenomenon in multi-channel CRNs has not yet been analyzed. In this
work, we present a continuous-time Markov chain (CTMC) model in which the
blocked/preempted secondary users (SUs) enter a finite retrial group (or orbit)
and re-attempt independently for service in an exponentially distributed random
manner. Taking into account the inherent retrial tendency of SUs, we
numerically assess the performance of the proposed scheme in terms of dropping
probability and throughput of SUs.


title:
Emission of neutron-proton and proton-proton pairs in neutrino
  scattering

abstract:
  We use a recently developed model of relativistic meson-exchange currents to
compute the neutron-proton and proton-proton yields in $(\nu_\mu,\mu^-)$
scattering from $^{12}$C in the 2p-2h channel. We compute the response
functions and cross sections with the relativistic Fermi gas model for
different kinematics from intermediate to high momentum transfers. We find a
large contribution of neutron-proton configurations in the initial state, as
compared to proton-proton pairs. In the case of charge-changing neutrino
scattering the 2p-2h cross section of proton-proton emission ({\it i.e.,} np in
the initial state) is much larger than for neutron-proton emission ({\it i.e.,}
two neutrons in the initial state) by a $(\omega,q)$-dependent factor. The
different emission probabilities of distinct species of nucleon pairs are
produced in our model only by meson-exchange currents, mainly by the $\Delta$
isobar current. We also analyze other effects including exchange contributions
and the effect of the axial and vector currents.


title: Speed and Efficiency Limits of Multilevel Incoherent Heat Engines

abstract:
  We present a comprehensive theory of heat engines (HE) based on a
quantum-mechanical "working fluid" (WF) with periodically-modulated energy
levels. The theory is valid for any periodicity of driving Hamiltonians that
commute with themselves at all times and do not induce coherence in the WF.
Continuous and stroke cycles arise in opposite limits of this theory, which
encompasses hitherto unfamiliar cycle forms, dubbed here hybrid cycles. The
theory allows us to discover the speed, power and efficiency limits attainable
by incoherently-operating multilevel HE depending on the cycle form and the
dynamical regimes.


title: Fall-colorings and b-colorings of graph products

abstract:
  Given a proper coloring $f$ of a graph $G$, a b-vertex in $f$ is a vertex
that is adjacent to every color class but its own. It is a b-coloring if every
color class contains at least one b-vertex, and it is a fall-coloring if every
vertex is a b-vertex. The b-chromatic number of $G$ is the maximum integer
$b(G)$ for which $G$ has a b-coloring with $b(G)$ colors, while the
fall-chromatic number and the fall-acromatic number of $G$ are, respectively,
the minimum and maximum integers $f_1(G),f_2(G)$ for which $G$ has a
fall-coloring. In this article, we explore the concepts of b-homomorphisms and
Type II homomorphisms, which generalize the concepts of b-colorings and
fall-colorings, and present some meta-theorems concerning products of graphs.
As a result, we derive some previously known facts about these metrics on graph
products. We also give a negative answer to a question posed by Kaul and
Mitillos about fall-colorings of perfect graphs.


title:
GRB 110530A: Peculiar Broad Bump and Delayed Plateau in Early Optical
  Afterglows

abstract:
  We report our very early optical observations of GRB 110530A and investigate
its jet properties together with its X-ray afterglow data. A peculiar broad
onset bump followed by a plateau is observed in its early R band afterglow
lightcurve. The optical data in the other bands and the X-ray data are well
consistent with the temporal feature of the R band lightcurve. Our joint
spectral fits of the optical and X-ray data show that they are in the same
regime, with a photon index of $\sim 1.70$. The optical and X-ray afterglow
lightcurves are well fitted with the standard external shock model by
considering a delayed energy injection component. Based on our modeling
results, we find that the radiative efficiency of the GRB jet is $\sim 1\%$ and
the magnetization parameter of the afterglow jet is $<0.04$ with the derived
extremely low $\epsilon_B$ (the fraction of shock energy to magnetic field) of
$(1.64\pm 0.25)\times 10^{-6}$. These results indicate that the jet may be
matter dominated. Discussion on delayed energy injection from accretion of late
fall-back material of its pre-supernova star is also presented.


title:
Further Results of the Cryptographic Properties on the Butterfly
  Structures

abstract:
  Recently, a new structure called butterfly introduced by Perrin et at. is
attractive for that it has very good cryptographic properties: the differential
uniformity is at most equal to 4 and algebraic degree is also very high when
exponent $e=3$. It is conjecture that the nonlinearity is also optimal for
every odd $k$, which was proposed as a open problem. In this paper, we further
study the butterfly structures and show that these structure with exponent
$e=2^i+1$ have also very good cryptographic properties. More importantly, we
prove in theory the nonlinearity is optimal for every odd $k$, which completely
solve the open problem. Finally, we study the butter structures with trivial
coefficient and show these butterflies have also optimal nonlinearity.
Furthermore, we show that the closed butterflies with trivial coefficient are
bijective as well, which also can be used to serve as a cryptographic
primitive.


title: Kernel functions based on triplet comparisons

abstract:
  Given only information in the form of similarity triplets "Object A is more
similar to object B than to object C" about a data set, we propose two ways of
defining a kernel function on the data set. While previous approaches construct
a low-dimensional Euclidean embedding of the data set that reflects the given
similarity triplets, we aim at defining kernel functions that correspond to
high-dimensional embeddings. These kernel functions can subsequently be used to
apply any kernel method to the data set.


title:
Fractional magnetization plateaux of the spin-1/2 Heisenberg
  orthogonal-dimer chain revisited: strong-coupling approach developed from the
  exactly solved Ising-Heisenberg model

abstract:
  The spin-1/2 Heisenberg orthogonal-dimer chain is considered within the
perturbative strong-coupling approach, which is developed from the exactly
solved spin-1/2 Ising-Heisenberg orthogonal-dimer chain with the Heisenberg
intradimer and the Ising interdimer couplings. Although the spin-1/2
Ising-Heisenberg orthogonal-dimer chain exhibits just intermediate plateaux at
zero, one-quarter and one-half of the saturation magnetization, the
perturbative treatment up to second order stemming from this exactly solvable
model additionally corroborates the fractional one-third plateau as well as the
gapless Luttinger spin-liquid phase. It is evidenced that the approximate
results obtained from the strong-coupling approach are in an excellent
agreement with the state-of-the-art numerical data obtained for the spin-1/2
Heisenberg orthogonal-dimer chain within the exact diagonalization and
density-matrix renormalization group method. The nature of individual quantum
ground states is comprehensively studied within the developed perturbation
theory.


title:
The iterative reweighted Mixed-Norm Estimate for spatio-temporal MEG/EEG
  source reconstruction

abstract:
  Source imaging based on magnetoencephalography (MEG) and
electroencephalography (EEG) allows for the non-invasive analysis of brain
activity with high temporal and good spatial resolution. As the
bioelectromagnetic inverse problem is ill-posed, constraints are required. For
the analysis of evoked brain activity, spatial sparsity of the neuronal
activation is a common assumption. It is often taken into account using convex
constraints based on the l1-norm. The resulting source estimates are however
biased in amplitude and often suboptimal in terms of source selection due to
high correlations in the forward model. In this work, we demonstrate that an
inverse solver based on a block-separable penalty with a Frobenius norm per
block and a l0.5-quasinorm over blocks addresses both of these issues. For
solving the resulting non-convex optimization problem, we propose the iterative
reweighted Mixed Norm Estimate (irMxNE), an optimization scheme based on
iterative reweighted convex surrogate optimization problems, which are solved
efficiently using a block coordinate descent scheme and an active set strategy.
We compare the proposed sparse imaging method to the dSPM and the RAP-MUSIC
approach based on two MEG data sets. We provide empirical evidence based on
simulations and analysis of MEG data that the proposed method improves on the
standard Mixed Norm Estimate (MxNE) in terms of amplitude bias, support
recovery, and stability.


title:
Generalized squeezing rotating-wave approximation to the isotropic and
  anisotropic Rabi model in the ultrastrong-coupling regime

abstract:
  Generalized squeezing rotating-wave approximation (GSRWA) is proposed by
employing both the displacement and the squeezing transformations. A solvable
Hamiltonian is reformulated in the same form as the ordinary RWA ones. For a
qubit coupled to oscillators experiment, a well-defined
Schr\"{o}dinger-cat-like entangled state is given by the displaced-squeezed
oscillator state instead of the original displaced state. For the isotropic
Rabi case, the mean photon number and the ground-state energy are expressed
analytically with additional squeezing terms, exhibiting a substantial
improvement of the GSRWA. And the ground-state energy in the anisotropic Rabi
model confirms the effectiveness of the GSRWA. Due to the squeezing effect, the
GSRWA improves the previous methods only with the displacement transformation
in a wide range of coupling strengths even for large atom frequency.


title: Renormalization Group Equation for $f(R)$ gravity on hyperbolic spaces

abstract:
  We derive the flow equation for the gravitational effective average action in
an $f(R)$ truncation on hyperbolic spacetimes using the exponential
parametrization of the metric. In contrast to previous works on compact spaces,
we are able to evaluate traces exactly using the optimised cutoff. This reveals
in particular that all modes can be integrated out for a finite value of the
cutoff due to a gap in the spectrum of the Laplacian, leading to the effective
action. Studying polynomial solutions, we find poorer convergence than has been
found on compact spacetimes even though at small curvature the equations only
differ in the treatment of certain modes. In the vicinity of an asymptotically
free fixed point, we find the universal beta function for the $R^2$ coupling
and compute the corresponding effective action which involves an $R^2 \log R^2$
quantum correction.


title:
Multipartite Interacting Scalar Dark Matter in the light of updated LUX
  data

abstract:
  We explore constraints on multipartite dark matter (DM) framework composed of
singlet scalar DM interacting with the Standard Model (SM) through Higgs portal
coupling. We compute relic density and direct search constraints including the
updated LUX bound for two component scenario with non-zero interactions between
two DM components in $\mathcal{Z}_2\times \mathcal{Z}_2^{'}$ framework in
comparison with the one having $\mathcal{O}(2)$ symmetry. We point out
availability of a significantly large region of parameter space of such a
multipartite model with DM-DM interactions.


title:
Fusion-fission probabilities, cross sections and structure notes of
  super-heavy nuclei

abstract:
  Fusion - fission probabilities in the synthesis of heaviest elements are
discussed in the context of the latest experimental reports. Cross sections for
superheavy nuclei are evaluated using "Fusion by Diffusion" (FBD) model.
Predictive power of this approach is shown for experimentally known Lv, Og
isotopes and predictions given for Z=119,120. Ground state and saddle point
properties as: masses, shell corrections, pairing energies and deformations
necessary for cross section estimations are calculated systematically within
the multidimensional microscopic - macroscopic method based on the deformed
Woods-Saxon single particle potential. In the frame of FBD approach predictions
for production of elements heavier than Z = 118 are not too optimistic. For
this reason, and because of high instability of superheavy nuclei, we comment
on some structure effects, connected with the K-isomerism phenomenon which
could lead to a significant increase in the stability of these systems.


title: A Degenerate Isoperimetric Problem in the Plane

abstract:
  We establish sufficient conditions for existence of curves minimizing length
as measured with respect to a degenerate metric on the plane while enclosing a
specified amount of Euclidean area. Non-existence of minimizers can occur and
examples are provided. This continues the investigation begun in [ABCDS] where
the metric ds^2 near the singularities equals a quadratic polynomial times the
standard metric. Here we allow the conformal factor to be any smooth
non-negative potential vanishing at isolated points provided the Hessian at
these points is positive definite. These isoperimetric curves, appropriately
parametrized, arise as traveling wave solutions to a bi-stable Hamiltonian
system.


title: On effective equidistribution for quotients of SL(d)

abstract:
  We prove the first case of polynomially effective equidistribution of closed
orbits of semisimple groups with nontrivial centralizer. The proof relies on
uniform spectral gap, builds on, and extends work of Einsiedler, Margulis, and
Venkatesh.


title:
Cyclic cohomology for graded $C^{*,r}$-algebras and its pairings with
  van Daele $K$-theory

abstract:
  We consider cycles for graded $C^{*,r}$-algebras (Real $C^{*}$-algebras)
which are compatible with the $*$-structure and the real structure. Their
characters are cyclic cocycles. We define a Connes type pairing between such
characters and elements of the van Daele $K$-groups of the $C^{*,r}$-algebra
and its real subalgebra. This pairing vanishes on elements of finite order. We
define a second type of pairing between characters and $K$-group elements which
is derived from a unital inclusion of $C^{*}$-algebras. It is potentially
non-trivial on elements of order two and torsion valued. Such torsion valued
pairings yield topological invariants for insulators. The two-dimensional
Kane-Mele and the three-dimensional Fu-Kane-Mele strong invariant are special
cases of torsion valued pairings. We compute the pairings for a simple class of
periodic models and establish structural results for two dimensional aperiodic
models with odd time reversal invariance.


title:
On a New Formulation of Vacuum Axisymmetric Solutions of general
  Relativity

abstract:
  Axisymmetric Solutions of the vacuum Einstein equations are found in the
Papapetrou-Weyl gauge. The solutions depend on two pairs of functionals, each
pair of two functions depends on a different arbitrarily chosen function of one
variable. Some examples are given.


title: Polyakov's formulation of $2d$ bosonic string theory

abstract:
  Using probabilistic methods, we first define Liouville quantum field theory
on Riemann surfaces of genus $\mathbf{g}\geq 2$ and show that it is a conformal
field theory. We use the partition function of Liouville quantum field theory
to give a mathematical sense to Polyakov's partition function of noncritical
bosonic string theory \cite{Pol} (also called $2d$ bosonic string theory) and
to Liouville quantum gravity. Then we show the convergence of Polyakov's
partition function over the moduli space of Riemann surfaces in genus
$\mathbf{g}\geq 2$ in the case of $D\leq 1$ boson. This is done by performing a
careful analysis of the behaviour of the partition function at the boundary of
moduli space. An essential feature of our approach is that it is probabilistic
and non perturbative. The interest of our result is twofold. First, to the best
of our knowledge, this is the first mathematical result about convergence of
string theories. Second, our construction describes conjecturally the scaling
limit of higher genus random planar maps weighted by Conformal Field Theories:
we make precise conjectures about this statement at the end of the paper.


title:
Modeling many-body physics with Slave-Spin Mean-Field: Mott and Hund's
  physics in Fe-superconductors

abstract:
  Slave-spin mean-field theory, a light and accurate technique to model
electronic correlations in Fermi-liquid phases of multi-orbital materials, is
pedagogically exposed in this chapter, with a focus on its recent successful
application to the physics of Iron-based superconductors. Beside introducing
electronic correlations and recalling the Fermi-liquid phenomenology, the
manuscript accompanies the step-by-step explanation of the slave-spin technique
with a set of useful complements providing analytical insight into Mott and
Hund's physics, which are at the heart of the physics of strongly correlated
materials. Some original research material is also exposed, such as the
Hund-induced shrinking of the Hubbard bands flanking the gap of the half-filled
Mott insulator, and the low-energy description of the "orbital-decoupling"
mechanism.


title:
Reconstruction of Sub-Surface Velocities from Satellite Observations
  Using Iterative Self-Organizing Maps

abstract:
  In this letter a new method based on modified self-organizing maps is
presented for the reconstruction of deep ocean current velocities from surface
information provided by satellites. This method takes advantage of local
correlations in the data-space to improve the accuracy of the reconstructed
deep velocities. Unlike previous attempts to reconstruct deep velocities from
surface data, our method makes no assumptions regarding the structure of the
water column, nor the underlying dynamics of the flow field. Using satellite
observations of surface velocity, sea-surface height and sea-surface
temperature, as well as observations of the deep current velocity from
autonomous Argo floats to train the map, we are able to reconstruct realistic
high--resolution velocity fields at a depth of 1000m. Validation reveals
extremely promising results, with a speed root mean squared error of ~2.8cm/s,
a factor more than a factor of two smaller than competing methods, and
direction errors consistently smaller than 30 degrees. Finally, we discuss the
merits and shortcomings of this methodology and its possible future
applications.


title:
Nonexistence of stable solutions to quasilinear elliptic equations on
  Riemannian manifolds

abstract:
  We prove nonexistence of nontrivial, possibly sign changing, stable solutions
to a class of quasilinear elliptic equations with a potential on Riemannian
manifolds, under suitable weighted volume growth conditions on geodesic balls.


title: Linear Response of Zero-Resistance States

abstract:
  A two-dimensional electron system in the presence of a magnetic field and
microwave irradiation can undergo a phase transition towards a zero-resistance
state. A widely used model predicts the zero-resistance state to be a domain
state, which responds to applied dc voltages or dc currents by slightly
changing the domain structure. Here we propose an alternative response
scenario, according to which the domain pattern remains unchanged.
Surprisingly, a fixed domain pattern does not destroy zero resistance, provided
that the resistance is direction independent. Otherwise, if the symmetry of the
domain pattern allows a direction dependence of the resistance, the domain
state can be dissipative. We give examples for both situations and simulate the
response behavior numerically.


title: An algorithm for motif-based network design

abstract:
  A determinant property of the structure of a biological network is the
distribution of local connectivity patterns, i.e., network motifs. In this
work, a method for creating directed, unweighted networks while promoting a
certain combination of motifs is presented. This motif-based network algorithm
starts with an empty graph and randomly connects the nodes by advancing or
discouraging the formation of chosen motifs. The in- or out-degree distribution
of the generated networks can be explicitly chosen. The algorithm is shown to
perform well in producing networks with high occurrences of the targeted
motifs, both ones consisting of 3 nodes as well as ones consisting of 4 nodes.
Moreover, the algorithm can also be tuned to bring about global network
characteristics found in many natural networks, such as small-worldness and
modularity.


title: Quantum circuits and low-degree polynomials over F_2

abstract:
  In this work we explore a correspondence between quantum circuits and
low-degree polynomials over the finite field F_2. Any quantum circuit made up
of Hadamard, Z, controlled-Z and controlled-controlled-Z gates gives rise to a
degree-3 polynomial over F_2 such that calculating quantum circuit amplitudes
is equivalent to counting zeroes of the corresponding polynomial. We exploit
this connection, which is especially clean and simple for this particular gate
set, in two directions. First, we give proofs of classical hardness results
based on quantum circuit concepts. Second, we find efficient classical
simulation algorithms for certain classes of quantum circuits based on
efficient algorithms for classes of polynomials.


title: Hybrid Weyl Semimetal

abstract:
  We construct a tight-binding model realizing one pair of Weyl nodes and three
distinct Weyl semimetals. In the type-I (type-II) Weyl semimetal, both nodes
belong to type-I (type-II) Weyl nodes. In addition, there exists a novel type,
dubbed "hybrid Weyl semimetal", in which one Weyl node is of type-I while the
other is of type-II. For the hybrid Weyl semimetal, we further demonstrate the
bulk Fermi surfaces and the topologically protected surface states, analyze the
unique Landau level structure and quantum oscillation, and discuss the material
realization.


title:
A large eddy simulation (LES) study of inertial deposition of particles
  onto in-line tube-banks

abstract:
  We study deposition and impact of heavy particles onto an in-line tube-banks
within a turbulent cross flow through Lagrangian particle tracking coupled with
an LES modelling framework. The flow Reynolds number based on the cylinder
diameter D and flow velocity between the gap of two vertically adjacent
cylinders is 33960. We examine the flow structures across the tube bank and
report surface pressure characteristics on cylinders. Taking into account
particle-wall impact and bounce, we study dispersion and deposition of three
sets of particles (St = 0.35, 0.086, 0.0075) based on 107 particles tracked
through the turbulent flow resolved by LES. The deposition efficiency for the
three sets of particles are reported across the tube-banks. Positions of
particle deposited onto tube-banks shows that significantly more of smaller
particles deposit onto the back-side of the back-banks. This suggests that the
smaller particles are easier to be entrained into the wake and impact onto the
back-side of cylinders.


title: Massive two-column bosonic fields in the frame-like formalism

abstract:
  In this paper we develop the frame-like gauge invariant formulation for the
massive two-column bosonic fields in (anti) de Sitter space-times. We begin
with the partially massless cases in AdS and dS and then we combine these
results into the general massive theory. Separate section is devoted to the
special case where both columns have equal number of indices.


title: SSDH: Semi-supervised Deep Hashing for Large Scale Image Retrieval

abstract:
  Hashing methods have been widely used for efficient similarity retrieval on
large scale image database. Traditional hashing methods learn hash functions to
generate binary codes from hand-crafted features, which achieve limited
accuracy since the hand-crafted features cannot optimally represent the image
content and preserve the semantic similarity. Recently, several deep hashing
methods have shown better performance because the deep architectures generate
more discriminative feature representations. However, these deep hashing
methods are mainly designed for supervised scenarios, which only exploit the
semantic similarity information, but ignore the underlying data structures. In
this paper, we propose the semi-supervised deep hashing (SSDH) approach, to
perform more effective hash function learning by simultaneously preserving
semantic similarity and underlying data structures. The main contributions are
as follows: (1) We propose a semi-supervised loss to jointly minimize the
empirical error on labeled data, as well as the embedding error on both labeled
and unlabeled data, which can preserve the semantic similarity and capture the
meaningful neighbors on the underlying data structures for effective hashing.
(2) A semi-supervised deep hashing network is designed to extensively exploit
both labeled and unlabeled data, in which we propose an online graph
construction method to benefit from the evolving deep features during training
to better capture semantic neighbors. To the best of our knowledge, the
proposed deep network is the first deep hashing method that can perform hash
code learning and feature learning simultaneously in a semi-supervised fashion.
Experimental results on 5 widely-used datasets show that our proposed approach
outperforms the state-of-the-art hashing methods.


title: Imaging current-induced switching of antiferromagnetic domains in CuMnAs

abstract:
  The magnetic order in antiferromagnetic (AF) materials is hard to control
with external magnetic fields. However, recent advances in detecting and
manipulating AF order electrically have opened up new prospects for these
materials in basic and applied spintronics research. Using x-ray magnetic
linear dichroism microscopy, we show here that staggered effective fields
generated by electrical current can induce reproducible and reversible
modification of the antiferromagnetic domain structure in microdevices
fabricated from a tetragonal CuMnAs thin film. The current-induced domain
switching is inhomogeneous at the submicron level. A clear correlation between
the average domain orientation and the anisotropy of the electrical resistance
is demonstrated.


title:
Hegemonic structure of basic, clinical and patented knowledge on Ebola
  research: a US army reductionist initiative

abstract:
  Background: In this paper, we present an approach to understand how the
basic, clinical and patent knowledge on Ebola is organized and
intercommunicated and what leading factor could be shaping the evolution of the
knowledge translation process for this disease. Methodology: A combination of
citation network analysis; analysis of Medical heading Subject (MeSH) and Gene
Ontology (GO) terms, and quantitative content analysis for patents and
scientific literature, aimed to map the organization of Ebola research was
carried out. Results: We found six putative research fronts (i.e. clusters of
high interconnected papers). Three research fronts are basic research on Ebola
virus structural proteins: glycoprotein, VP40 and VP35, respectively. There is
a fourth research front of basic research papers on pathogenesis, which is the
organizing hub of Ebola research. A fifth research front is pre-clinical
research focused on vaccines and glycoproteins. Finally, a
clinical-epidemiology research front related to the disease outbreaks was
identified. The network structure of patent families shows that the dominant
design is the use of Ebola virus proteins as targets of vaccines and other
immunological treatments. Therefore, patents network organization resembles the
organization of the scientific literature. Specifically, the knowledge on Ebola
would flow from higher (clinical-epidemiology) to intermediated
(cellular-tissular pathogenesis) to lower (molecular interactions) levels of
organization. Conclusion: Our results suggest a strong reductionist approach
for Ebola research probably influenced by the lethality of the disease. On the
other hand, the ownership profile of the patent families network and the main
researches relationship with the United State Army suggest a strong involvement
of this military institution in Ebola research.


title: Mean-Payoff Games on Timed Automata

abstract:
  Mean-payoff games on timed automata are played on the infinite weighted graph
of configurations of priced timed automata between two players, Player Min and
Player Max, by moving a token along the states of the graph to form an infinite
run. The goal of Player Min is to minimize the limit average weight of the run,
while the goal of the Player Max is the opposite. Brenguier, Cassez, and Raskin
recently studied a variation of these games and showed that mean-payoff games
are undecidable for timed automata with five or more clocks. We refine this
result by proving the undecidability of mean-payoff games with three clocks. On
a positive side, we show the decidability of mean-payoff games on one-clock
timed automata with binary price-rates. A key contribution of this paper is the
application of dynamic programming based proof techniques applied in the
context of average reward optimization on an uncountable state and action
space.


title:
A Nonlocal Denoising Algorithm for Manifold-Valued Images Using Second
  Order Statistics

abstract:
  Nonlocal patch-based methods, in particular the Bayes' approach of Lebrun,
Buades and Morel (2013), are considered as state-of-the-art methods for
denoising (color) images corrupted by white Gaussian noise of moderate
variance. This paper is the first attempt to generalize this technique to
manifold-valued images. Such images, for example images with phase or
directional entries or with values in the manifold of symmetric positive
definite matrices, are frequently encountered in real-world applications.
Generalizing the normal law to manifolds is not canonical and different
attempts have been considered. Here we focus on a straightforward intrinsic
model and discuss the relation to other approaches for specific manifolds. We
reinterpret the Bayesian approach of Lebrun et al. (2013) in terms of minimum
mean squared error estimation, which motivates our definition of a
corresponding estimator on the manifold. With this estimator at hand we present
a nonlocal patch-based method for the restoration of manifold-valued images.
Various proof of concept examples demonstrate the potential of the proposed
algorithm.


title:
Early and Late Time Acoustic Measures for Underwater Seismic Airgun
  Signals In Long-Term Acoustic Data Sets

abstract:
  This work presents a new toolkit for describing the acoustic properties of
the ocean environment before, during and after a sound event caused by an
underwater seismic air-gun. The toolkit uses existing sound measures, but
uniquely applies these to capture the early time period (actual pulse) and late
time period (reverberation and multiple arrivals). In total, 183 features are
produced for each air-gun sound. This toolkit was utilized on data retrieved
from a field deployment encompassing five marine autonomous recording units
during a 46-day seismic air-gun survey in Baffin Bay, Greenland. Using this
toolkit, a total of 147 million data points were identified from the Greenland
deployment recordings. The feasibility of extracting a large number of features
was then evaluated using two separate methods: a serial computer and a high
performance system. Results indicate that data extraction performance took an
estimated 216 hours for the serial system, and 18 hours for the high
performance computer. This paper provides an analytical description of the new
toolkit along with details for using it to identify relevant data.


title:
Large-scale deformed quasiparticle random-phase approximation
  calculations of the $\gamma$-ray strength function using the Gogny force

abstract:
  Valuable theoretical predictions of nuclear dipole excitations in the whole
chart are of great interest for different nuclear applications, including in
particular nuclear astrophysics. Here we present large-scale calculations of
the $E1$ $\gamma$-ray strength function obtained in the framework of the
axially-symmetric deformed QRPA based on the finite-range Gogny force. This
approach is applied to even-even nuclei, the strength function for odd nuclei
being derived by interpolation. The convergence with respect to the adopted
number of harmonic oscillator shells and the cut-off energy introduced in the
2-quasiparticle (2-$qp$) excitation space is analyzed. The calculations
performed with two different Gogny interactions, namely D1S and D1M, are
compared. A systematic energy shift of the $E1$ strength is found for D1M
relative to D1S, leading to a lower energy centroid and a smaller
energy-weighted sum rule for D1M. When comparing with experimental
photoabsorption data, the Gogny-QRPA predictions are found to overestimate the
giant dipole energy by typically $\sim$2 MeV. Despite the microscopic nature of
our self-consistent Hartree-Fock-Bogoliubov plus QRPA calculation, some
phenomenological corrections need to be included to take into account the
effects beyond the standard 2-$qp$ QRPA excitations and the coupling between
the single-particle and low-lying collective phonon degrees of freedom. For
this purpose, three prescriptions of folding procedure are considered and
adjusted to reproduce experimental photoabsorption data at best. All of them
are shown to lead to rather similar predictions of the $E1$ strength, both at
low energies and for exotic neutron-rich nuclei. Predictions of $\gamma$-ray
strength functions and Maxwellian-averaged neutron capture rates for the whole
Sn isotopic chain are also discussed and compared with previous theoretical
calculations.


title: Compositional Reasoning for Interval Markov Decision Processes

abstract:
  Model checking probabilistic CTL properties of Markov decision processes with
convex uncertainties has been recently investigated by Puggelli et al. Such
model checking algorithms typically suffer from the state space explosion. In
this paper, we address probabilistic bisimulation to reduce the size of such an
MDP while preserving the probabilistic CTL properties it satisfies. In
particular, we discuss the key ingredients to build up the operations of
parallel composition for composing interval MDP components at run-time. More
precisely, we investigate how the parallel composition operator for interval
MDPs can be defined so as to arrive at a congruence closure. As a result, we
show that probabilistic bisimulation for interval MDPs is congruence with
respect to two facets of parallelism, namely synchronous product and
interleaving.


title:
A symbolic algebra for the computation of expected utilities in
  multiplicative influence diagrams

abstract:
  Influence diagrams provide a compact graphical representation of decision
problems. Several algorithms for the quick computation of their associated
expected utilities are available in the literature. However, often they rely on
a full quantification of both probabilistic uncertainties and utility values.
For problems where all random variables and decision spaces are finite and
discrete, here we develop a symbolic way to calculate the expected utilities of
influence diagrams that does not require a full numerical representation.
Within this approach expected utilities correspond to families of polynomials.
After characterizing their polynomial structure, we develop an efficient
symbolic algorithm for the propagation of expected utilities through the
diagram and provide an implementation of this algorithm using a computer
algebra system. We then characterize many of the standard manipulations of
influence diagrams as transformations of polynomials. We also generalize the
decision analytic framework of these diagrams by defining asymmetries as
operations over the expected utility polynomials.


title:
Mirror theorem for elliptic quasimap invariants of local Calabi-Yau
  varieties

abstract:
  The elliptic quasimap potential function is explicitly calculated for
Calabi-Yau complete intersections in projective spaces by Kim and Lho. We
extend this result to local Calabi-Yau varieties. Using this as well as the
wall crossing formula by Ciocan-Fontanine and Kim, we can calculate the
elliptic Gromov-Witten potential function.


title:
A Second-order Divergence-constrained Multidimensional Numerical Scheme
  for Relativistic Two-Fluid Electrodynamics

abstract:
  A new multidimensional simulation code for relativistic two-fluid
electrodynamics (RTFED) is described. The basic equations consist of the full
set of Maxwell's equations coupled with relativistic hydrodynamic equations for
separate two charged fluids, representing the dynamics of either an
electron-positron or an electron-proton plasma. It can be recognized as an
extension of conventional relativistic magnetohydrodynamics (RMHD). Finite
resistivity may be introduced as a friction between the two species, which
reduces to resistive RMHD in the long wavelength limit without suffering from a
singularity at infinite conductivity. A numerical scheme based on HLL
(Harten-Lax-Van Leer) Riemann solver is proposed that exactly preserves the two
divergence constraints for Maxwell's equations simultaneously. Several
benchmark problems demonstrate that it is capable of describing RMHD
shocks/discontinuities at long wavelength limit, as well as dispersive
characteristics due to the two-fluid effect appearing at small scales. This
shows that the RTFED model is a promising tool for high energy astrophysics
application.

categories: astro-ph.HE physics.comp-ph physics.plasm-ph physics.space-ph


title:
Birkhoff-James orthogonality of linear operators on finite dimensional
  Banach spaces

abstract:
  In this paper we characterize Birkhoff-James orthogonality of linear
operators defined on a finite dimensional real Banach space $ \mathbb{X}. $ We
also explore the symmetry of Birkhoff-James orthogonality of linear operators
defined on $ \mathbb{X}. $ Using some of the related results proved in this
paper, we finally prove that $ T \in \mathbb{L}(l_{p}^2) (p \geq 2, p \neq
\infty) $ is left symmetric with respect to Birkhoff-James orthogonality if and
only if $ T $ is the zero operator. We conjecture that the result holds for any
finite dimensional strictly convex and smooth real Banach space $ \mathbb{X}, $
in particular for the Banach spaces $ l_{p}^{n} (p > 1, p \neq \infty). $


title: Nonlinear Control of an AC-connected DC MicroGrid

abstract:
  New connection constraints for the power network (Grid Codes) require more
flexible and reliable systems, with robust solutions to cope with uncertainties
and intermittence from renewable energy sources (renewables), such as
photovoltaic arrays. A solution for interconnecting such renewables to the main
grid is to use storage systems and a Direct Current (DC) MicroGrid. A "Plug and
Play" approach based on the "System of Systems" philosophy using distributed
control methodologies is developed in the present work. This approach allows to
interconnect a number of elements to a DC MicroGrid as power sources like
photovoltaic arrays, storage systems in different time scales like batteries
and supercapacitors, and loads like electric vehicles and the main AC grid. The
proposed scheme can easily be scalable to a much larger number of elements.


title:
Thermodynamics of a one-dimensional self-gravitating gas with periodic
  boundary conditions

abstract:
  We study the thermodynamical properties of a one-dimensional gas with
one-dimensional gravitational interactions, and placed in a uniform mass
background. Periodic boundary conditions are implemented as a modification of
the potential consisting of a sum over mirror images (Ewald sum), regularized
with an exponential cut-off. The system has a phase transition at a critical
temperature. Above the critical temperature the gas density is uniform, while
below the critical point the system becomes inhomogeneous. Numerical
simulations of the model confirms the existence of the phase transition, and
are in good agreement with the theoretical results.


title: Landau-Zener-St\"uckelberg Interferometry for Majorana Qubit

abstract:
  Stimulated by a very recent experiment observing successfully two
superconducting states with even- and odd-number of electrons in a nanowire
topological superconductor as expected from the existence of two end Majorana
quasiparticles (MQs) [Albrecht \textit{et al.}, Nature \textbf{531}, 206
(2016)], we propose a way to manipulate Majorana qubit exploiting quantum
tunneling effects. The prototype setup consists of two one-dimensional (1D)
topological superconductors coupled by a tunneling junction which can be
controlled by gate voltage. We show that, upon current injection, the time
evolution of superconducting phase difference at the junction induces an
oscillation in energy levels of the Majorana parity states, whereas the
level-crossing is avoided by a small coupling energy of MQs in the individual
1D superconductors. This results in a Landau-Zener-St\"{u}ckelberg (LZS)
interference between the Majorana parity states. Adjusting the current pulse
and gate voltage, one can build a LZS interferometry which provides an
arbitrary manipulation of the Majorana qubit. The LZS rotation of Majorana
qubit can be monitored by the microwave radiated from the junction.


title: On the polynomial convergence rate to nonequilibrium steady-states

abstract:
  We consider a stochastic energy exchange model that models the 1D microscopic
heat conduction in the nonequilibrium setting. In this paper, we prove the
existence and uniqueness of the nonequilibrium steady state (NESS) and,
furthermore, the polynomial speed of convergence to the NESS. Our result shows
that the asymptotic properties of this model and its deterministic dynamical
system origin are consistent. The proof uses a new technique called the induced
chain method. We partition the state space and work on both the Markov chain
induced by an "active set" and the tail of return time to this "active set".


title: Design of a new tracking device for on-line dose monitor in ion therapy

abstract:
  Charged Particle Therapy is a technique for cancer treatment that exploits
hadron beams, mostly protons and carbons. A critical issue is the monitoring of
the dose released by the beam to the tumor and to the surrounding tissues. We
present the design of a new tracking device for monitoring on-line the dose in
ion therapy through the detection of secondary charged particles produced by
the beam interactions in the patient tissues. In fact, the charged particle
emission shape can be correlated with the spatial dose release and the Bragg
peak position. The detector uses the information provided by 12 layers of
scintillating fibers followed by a plastic scintillator and a small calorimeter
made of a pixelated Lutetium Fine Silicate crystal. Simulations have been
performed to evaluate the achievable spatial resolution and a possible
application of the device for the monitoring of the dose profile in a real
treatment is presented.


title: High efficiency gaseous tracking detector for cosmic muon radiography

abstract:
  A tracking detector system has been constructed with an innovative approach
to the classical multi-wire proportional chamber concept, using contemporary
technologies. The detectors, covering an area of 0.58 square meters each, are
optimized for the application of muon radiography. The main features are high
(>99.5%) and uniform detection efficiency, 9 mm FWHM position resolution,
filling gas consumption below 2 liters per hour for the non toxic, non
flammable argon and carbon dioxide mixture. These parameters, along with the
simplicity of the construction and the tolerance for mechanical effects, make
the detectors to be a viable option for a large area muography observation
system.


title:
Simple modules for the partition algebra and monotone convergence of
  Kronecker coefficients

abstract:
  We construct bases of the simple modules for partition algebras which are
indexed by paths in an alcove geometry. This allows us to give a concrete
interpretation (and new proof) of the monotone convergence property for
Kronecker coefficients using stratifications of the cell modules of the
partition algebra.


title: On the roots of the node reliability polynomial

abstract:
  Given a graph $G$ whose edges are perfectly reliable and whose nodes each
operate independently with probability $p\in[0,1],$ the node reliability of $G$
is the probability that at least one node is operational and that the
operational nodes can all communicate in the subgraph that they induce; it is
the analogous node measure of robustness to the well studied
\textit{all-terminal reliability}, where the nodes are perfectly reliable but
the edges fail randomly. In sharp contrast to what is known about the roots of
the all-terminal reliability polynomial, we show that the node reliability
polynomial of any connected graph on at least three nodes has a nonreal
polynomial root, the collection of real roots of all node reliability
polynomials is unbounded, and the collection of complex roots of all node
reliability polynomials is dense in the entire complex plane.


title:
On Varying Topology of Complex Networks and Performance Limitations of
  Community Detection Algorithms

abstract:
  One of the most widely studied problem in mining and analysis of complex
networks is the detection of community structures. The problem has been
extensively studied by researchers due to its high utility and numerous
applications in various domains. Many algorithmic solutions have been proposed
for the community detection problem but the quest to find the best algorithm is
still on. More often than not, researchers focus on developing fast and
accurate algorithms that can be generically applied to networks from a variety
of domains without taking into consideration the structural and topological
variations in these networks.
  In this paper, we evaluate the performance of different clustering algorithms
as a function of varying network topology. Along with the well known LFR model
to generate benchmark networks with communities,we also propose a new model
named Naive Scale Free Model to study the behavior of community detection
algorithms with respect to different topological features. More specifically,
we are interested in the size of networks, the size of community structures,
the average connectivity of nodes and the ratio of inter-intra cluster edges.
Results reveal several limitations of the current popular network clustering
algorithms failing to correctly find communities. This suggests the need to
revisit the design of current clustering algorithms that fail to incorporate
varying topological features of different networks.


title: A Two-Stage Active-Set Algorithm for Bound-Constrained Optimization

abstract:
  In this paper, we describe a two-stage method for solving optimization
problems with bound constraints. It combines the active-set estimate described
in [Facchinei and Lucidi, 1995] with a modification of the non-monotone line
search framework recently proposed in [De Santis et al., 2012]. In the first
stage, the algorithm exploits a property of the active-set estimate that
ensures a significant reduction in the objective function when setting to the
bounds all those variables estimated active. In the second stage, a
truncated-Newton strategy is used in the subspace of the variables estimated
non-active. In order to properly combine the two phases, a proximity check is
included in the scheme. This new tool, together with the other theoretical
features of the two stages, enables us to prove global convergence.
Furthermore, under additional standard assumptions, we can show that the
algorithm converges at a superlinear rate. Promising experimental results
demonstrate the effectiveness of the proposed method.