title: Black Hole Entropy from indistinguishable quantum geometric excitations

abstract:
  In loop quantum gravity, the quantum geometry of a black hole horizon consist
of discrete non-perturbative quantum geometric excitations (or punctures)
labeled by spins, which are responsible for the quantum area of the horizon. If
these punctures are compared to a gas of particles, then the spins associated
with the punctures can be viewed as single puncture area levels analogous to
single particle energy levels. Consequently, if we {\it assume} these punctures
to be {\it indistinguishable}, the microstate count for the horizon resembles
that of Bose-Einstein counting formula for gas of particles. For the
Bekenstein-Hawking area law(BHAL) to follow from the entropy calculation in the
large area limit, the Barbero-Immirzi parameter($\g$) approximately takes a
constant value.


title: The multifaceted planetesimal formation process

abstract:
  Accumulation of dust and ice particles into planetesimals is an important
step in the planet formation process. Planetesimals are the seeds of both
terrestrial planets and the solid cores of gas and ice giants forming by core
accretion. Left-over planetesimals in the form of asteroids, trans-Neptunian
objects and comets provide a unique record of the physical conditions in the
solar nebula. Debris from planetesimal collisions around other stars signposts
that the planetesimal formation process, and hence planet formation, is
ubiquitous in the Galaxy. The planetesimal formation stage extends from
micrometer-sized dust and ice to bodies which can undergo run-away accretion.
The latter ranges in size from 1 km to 1000 km, dependent on the planetesimal
eccentricity excited by turbulent gas density fluctuations. Particles face many
barriers during this growth, arising mainly from inefficient sticking,
fragmentation and radial drift. Two promising growth pathways are mass
transfer, where small aggregates transfer up to 50% of their mass in high-speed
collisions with much larger targets, and fluffy growth, where aggregate cross
sections and sticking probabilities are enhanced by a low internal density. A
wide range of particle sizes, from mm to 10 m, concentrate in the turbulent gas
flow. Overdense filaments fragment gravitationally into bound particle clumps,
with most mass entering planetesimals of contracted radii from 100 to 500 km,
depending on local disc properties. We propose a hybrid model for planetesimal
formation where particle growth starts unaided by self-gravity but later
proceeds inside gravitationally collapsing pebble clumps to form planetesimals
with a wide range of sizes.


title:
Imprints of the Standard Model in the Sky: Gravitational Waves from the
  decay of the Higgs after inflation

abstract:
  The existence of the Standard Model (SM) Higgs implies that a gravitational
wave (GW) background is generated by the decay products of the Higgs, soon
after the end of inflation. Theoretically, all Yukawa and $SU(2)_L$ gauge
couplings of the SM are imprinted as features in the GW spectrum. In practice,
the signal from the most strongly coupled species dominates, rendering
inaccesible the information on the other species. If detected, this background
could be used for measuring properties of high-energy particle physics,
including beyond the SM. To achieve this goal, new high frequency GW detection
technology is required, beyond that of currently planned detectors.


title: Reconstruction of Domain Wall Universe and Localization of Gravity

abstract:
  We construct a four-dimensional domain wall universe by using the Brans-Dicke
type gravity with two scalar field. We give a formulation where for arbitrarily
given warp factor and scale factor, we construct an action which reproduces
both of the warp and scale factors as a solution of the Einstein equation and
the field equations given by the action. This formulation could be called as
reconstruction. We show that the model does not contain ghost with negative
kinetic term and there occur the localization of gravity as in the
Randall-Sundrum model. It should be noted that in the equation of the graviton,
there appear extra terms related with the extra dimension, which might affect
the tensor mode in the fluctuations


title:
Simulation work on Fractional Order PI{\lambda} Control Strategy for
  speed control of DC motor based on stability boundary locus method

abstract:
  This paper deals with the design of Fractional Order Proportional Integral
(FO-PI{\lambda}) controller for the speed control of DC motor. A mathematical
model of DC motor control system is derived and based on this model fractional
order PI{\lambda} controller is designed using stability boundary locus method
to satisfy required gain margin (GM) and phase margin (PM) of the system. Servo
and Regulatory tracking simulation runs are carried out for the speed control
of DC motor. The performance of the fractional order PI{\lambda}
(FO-PI{\lambda}) controller is compared with Integer Order Relay Feedback
Proportional Integral (IO-RFPI) controller. Finally the stability of both
control system is considered.


title:
A Cellular Automata based Optimal Edge Detection Technique using
  Twenty-Five Neighborhood Model

abstract:
  Cellular Automata (CA) are common and most simple models of parallel
computations. Edge detection is one of the crucial task in image processing,
especially in processing biological and medical images. CA can be successfully
applied in image processing. This paper presents a new method for edge
detection of binary images based on two dimensional twenty five neighborhood
cellular automata. The method considers only linear rules of CA for extraction
of edges under null boundary condition. The performance of this approach is
compared with some existing edge detection techniques. This comparison shows
that the proposed method to be very promising for edge detection of binary
images. All the algorithms and results used in this paper are prepared in
MATLAB.


title: Dissimilarity-based Ensembles for Multiple Instance Learning

abstract:
  In multiple instance learning, objects are sets (bags) of feature vectors
(instances) rather than individual feature vectors. In this paper we address
the problem of how these bags can best be represented. Two standard approaches
are to use (dis)similarities between bags and prototype bags, or between bags
and prototype instances. The first approach results in a relatively
low-dimensional representation determined by the number of training bags, while
the second approach results in a relatively high-dimensional representation,
determined by the total number of instances in the training set. In this paper
a third, intermediate approach is proposed, which links the two approaches and
combines their strengths. Our classifier is inspired by a random subspace
ensemble, and considers subspaces of the dissimilarity space, defined by
subsets of instances, as prototypes. We provide guidelines for using such an
ensemble, and show state-of-the-art performances on a range of multiple
instance learning problems.


title:
Flux- and volume-limited groups/clusters for the SDSS galaxies:
  catalogues and mass estimation

abstract:
  We provide flux-limited and volume-limited galaxy group and cluster
catalogues, based on the spectroscopic sample of the SDSS data release 10
galaxies. We used a modified friends-of-friends (FoF) method with a variable
linking length in the transverse and radial directions to identify as many
realistic groups as possible. The flux-limited catalogue incorporates galaxies
down to m_r = 17.77 mag. It includes 588193 galaxies and 82458 groups. The
volume-limited catalogues are complete for absolute magnitudes down to M_r =
-18.0, -18.5, -19.0, -19.5, -20.0, -20.5, and -21.0; the completeness is
achieved within different spatial volumes, respectively. Our analysis shows
that flux-limited and volume-limited group samples are well compatible to each
other, especially for the larger groups/clusters. Dynamical mass estimates,
based on radial velocity dispersions and group extent in the sky, are added to
the extracted groups. The catalogues can be accessed via http://cosmodb.to.ee
and the Strasbourg Astronomical Data Center (CDS).


title:
Pump-probe scheme for electron-photon dynamics in hybrid
  conductor-cavity systems

abstract:
  Recent experiments on nanoscale conductors coupled to microwave cavities put
in prospect transport investigations of electron-photon interplay in the deep
quantum regime. Here we propose a pump-probe scheme to investigate the
transient dynamics of individual electron-photon excitations in a double
quantum dot-cavity system. Excitations pumped into the system decay via charge
tunneling at the double dot, probed in real time. We investigate theoretically
the short-time charge transfer statistics at the dot, for periodic pumping, and
show that this gives access to vacuum Rabi oscillations as well as excitation
dynamics in the presence of double dot dephasing and relaxation.


title:
A comment on "Weak value amplification is suboptimal for estimation and
  detection"

abstract:
  By assuming that the weak value is real, Ferrie and Combes render their
result inapplicable to weak measurement experiments which are aimed at
enhancing precision.


title: On Perturbations of Generators of $C_0$-Semigroups

abstract:
  We present a perturbation result for generators of $C_0$-semigroups which can
be considered as an operator theoretic version of the Weiss-Staffans
perturbation theorem for abstract linear systems. The result are illustrated by
applications to the Desch-Schappacher, the Miyadera Voigt perturbation
theorems, and to unbounded perturbations of the boundary conditions of a
generator.


title: Dust Evolution in Protoplanetary Disks

abstract:
  (abridged) In the core accretion scenario for the formation of planetary
rocky cores, the first step toward planet formation is the growth of dust
grains into larger and larger aggregates and eventually planetesimals. Although
dust grains are thought to grow from the submicron sizes typical of
interstellar dust to micron size particles in the dense regions of molecular
clouds and cores, the growth from micron size particles to pebbles and
kilometre size bodies must occur in protoplanetary disks. This step in the
formation of planetary systems is the last stage of solids evolution that can
be observed directly in young extrasolar systems.
  In this chapter we review the constraints on the physics of grain-grain
collisions as they have emerged from laboratory experiments and numerical
computations. We then review the current theoretical understanding of the
global processes governing the evolution of solids in protoplanetary disks,
including dust settling, growth, and radial transport. The predicted
observational signatures are summarized.
  We discuss recent developments in the study of grain growth in molecular
cloud cores and in collapsing envelopes of protostars as these provide the
initial conditions for the dust in disks. We discuss the observational evidence
for the growth of grains in young disks from mm surveys, as well as the recent
evidence of radial variations of the dust properties in disks. We include a
brief discussion of the constraints on the small end of the grain size
distribution and on dust settling as derived from optical and IR observations.
The observations are discussed in the context of global dust evolution models,
in particular we focus on the emerging evidence for a very efficient early
growth of grains and the radial distribution of grain sizes in disks. We also
highlight the limits of current models, including the need to slow the radial
drift of grains.


title: Fast-mode elimination in stochastic metapopulation models

abstract:
  We investigate the stochastic dynamics of entities which are confined to a
set of islands, between which they migrate. They are assumed to be one of two
types, and in addition to migration, they also reproduce and die. Systems which
fall into this class are common in biology and social science, occurring in
ecology, population genetics, epidemiology, biochemistry, linguistics, opinion
dynamics, and other areas. In all these cases the governing equations are
intractable, consisting as they do of multidimensional Fokker-Planck equations
or, equivalently, coupled nonlinear stochastic differential equations with
multiplicative noise. We develop a methodology which exploits a separation in
time scales between fast and slow variables to reduce these equations so that
they resemble those for a single island, which are amenable to analysis. The
technique is generally applicable, but we choose to discuss it in the context
of population genetics, in part because of the extra features that appear due
to selection. The idea behind the method is simple, its application systematic,
and the results in very good agreement with simulations of the full model for a
range of parameter values.


title:
Integration of an optical fiber taper with an optical microresonator
  fabricated in glass by femtosecond laser 3D micromachining

abstract:
  We report on fabrication of a microtoroid resonator of a high-quality factor
(i. e., Q-factor of ~3.24x10^6 measured under the critical coupling condition)
using femtosecond laser three-dimensional (3D) micromachining. Coupling of
light into and out of the microresonator has been realized with a fiber taper
that is reliably assembled with the microtoroid. The assembly of the fiber
taper to the microtoroid is achieved by welding the fiber taper onto the
sidewall of the microtoroid using CO2 laser irradiation. The integrated
microresonator maintains a high Q-factor of 3.21x10^5 as measured in air.


title:
Critical role of substrate in the high temperature superconductivity of
  single layer FeSe on Nb:BaTiO$_3$

abstract:
  In the quest for high temperature superconductors, the interface between a
metal and a dielectric was proposed to possibly achieve very high
superconducting transition temperature ($T_c$) through interface-assisted
pairing. Recently, in single layer FeSe (SLF) films grown on SrTiO$_3$
substrates, signs for $T_c$ up to 65~K have been reported. However, besides
doping electrons and imposing strain, whether and how the substrate facilitates
the superconductivity are still unclear. Here we report the growth of various
SLF films on thick BaTiO$_3$ films atop KTaO$_3$ substrates, with signs for
$T_c$ up to $75$~K, close to the liquid nitrogen boiling temperature. SLF of
similar doping and lattice is found to exhibit high $T_c$ only if it is on the
substrate, and its band structure strongly depends on the substrate. Our
results highlight the profound role of substrate on the high-$T_c$ in SLF, and
provide new clues for understanding its mechanism.


title: Discretizing stochastic dynamical systems using Lyapunov equations

abstract:
  Stochastic dynamical systems are fundamental in state estimation, system
identification and control. System models are often provided in continuous
time, while a major part of the applied theory is developed for discrete-time
systems. Discretization of continuous-time models is hence fundamental. We
present a novel algorithm using a combination of Lyapunov equations and
analytical solutions, enabling efficient implementation in software. The
proposed method circumvents numerical problems exhibited by standard algorithms
in the literature. Both theoretical and simulation results are provided.


title: Real-time Pedestrian Surveillance with Top View Cumulative Grids

abstract:
  This manuscript presents an efficient approach to map pedestrian surveillance
footage to an aerial view for global assessment of features. The analysis of
the footages relies on low level computer vision and enable real-time
surveillance. While we neglect object tracking, we introduce cumulative grids
on top view scene flow visualization to highlight situations of interest in the
footage. Our approach is tested on multiview footage both from RGB cameras and,
for the first time in the field, on RGB-D-sensors.


title: Quantum reservoirs with ion chains

abstract:
  Ion chains are promising platforms for studying and simulating quantum
reservoirs. One interesting feature is that their vibrational modes can mediate
entanglement between two objects which are coupled through the vibrational
modes of the chain. In this work we analyse entanglement between the transverse
vibrations of two heavy impurity defects embedded in an ion chain, which is
generated by the coupling with the chain vibrations. We verify general scaling
properties of the defects dynamics and demonstrate that entanglement between
the defects can be a stationary feature of these dynamics. We then analyse
entanglement in chains composed of tens of ions and propose a measurement
scheme which allows one to verify the existence of the predicted entangled
state.


title: Combining finite and continuous solvers

abstract:
  Combining efficiency with reliability within CP systems is one of the main
concerns of CP developers. This paper presents a simple and efficient way to
connect Choco and Ibex, two CP solvers respectively specialised on finite and
continuous domains. This enables to take advantage of the most recent advances
of the continuous community within Choco while saving development and
maintenance resources, hence ensuring a better software quality.


title: Osmosis with active solutes

abstract:
  Despite much current interest in active matter, little is known about osmosis
in active systems. Using molecular dynamics simulations, we investigate how
active solutes perturb osmotic steady states. We find that solute activity
increases the osmotic pressure, and can also expel solvent from the solution -
i.e. cause reverse osmosis. The latter effect cannot be described by an
effective temperature, but can be reproduced by mapping the active solution
onto a passive one with the same degree of local structuring as the passive
solvent component. Our results provide a basic framework for understanding
active osmosis, and suggest that activity-induced structuring of the passive
component may play a key role in the physics of active-passive mixtures.


title: Cascades of Multi-headed Chimera States for Coupled Phase Oscillators

abstract:
  Chimera state is a recently discovered dynamical phenomenon in arrays of
nonlocally coupled oscillators, that displays a self-organized spatial pattern
of co-existing coherence and incoherence. We discuss the appearance of the
chimera states in networks of phase oscillators with attractive and with
repulsive interactions, i.e. when the coupling respectively favors
synchronization or works against it. By systematically analyzing the dependence
of the spatiotemporal dynamics on the level of coupling
attractivity/repulsivity and the range of coupling, we uncover that different
types of chimera states exist in wide domains of the parameter space as
cascades of the states with increasing number of intervals of irregularity,
so-called chimera's heads. We report three scenarios for the chimera birth: 1)
via saddle-node bifurcation on a resonant invariant circle, also known as SNIC
or SNIPER, 2) via blue-sky catastrophe, when two periodic orbits, stable and
saddle, approach each other creating a saddle-node periodic orbit, and 3) via
homoclinic transition with complex multistable dynamics including an
"eight-like" limit cycle resulting eventually in a chimera state.


title:
A universal matter-wave interferometer with optical ionization gratings
  in the time domain

abstract:
  Matter-wave interferometry with atoms and molecules has attracted a rapidly
growing interest over the past two decades, both in demonstrations of
fundamental quantum phenomena and in quantum-enhanced precision measurements.
Such experiments exploit the non-classical superposition of two or more
position and momentum states which are coherently split and rejoined to
interfere. Here, we present the experimental realization of a universal
near-field interferometer built from three short-pulse single-photon ionization
gratings. We observe quantum interference of fast molecular clusters, with a
composite de Broglie wavelength as small as 275 fm. Optical ionization gratings
are largely independent of the specific internal level structure and are
therefore universally applicable to different kinds of nanoparticles, ranging
from atoms to clusters, molecules and nanospheres. The interferometer is
sensitive to fringe shifts as small as a few nanometers and yet robust against
velocity-dependent phase shifts, since the gratings exist only for nanoseconds
and form an interferometer in the time domain.


title: The three-gluon vertex in Landau gauge

abstract:
  We present the first Dyson-Schwinger calculation of the three-gluon vertex in
Landau-gauge QCD in which its full covariant structure is back-coupled
self-consistently. We truncate a Bose-symmetrized version of the DSE at the
level of one-loop diagrams, model the four-gluon vertex, and neglect terms that
contain non-primitively divergent n-point functions; the ghost-gluon vertex is
taken bare to good approximation. Fit functions for the ghost and gluon
propagators that interpolate between scaling and decoupling are presented. In
all aspects of our study Bose symmetry is manifest, from the truncation to the
basis decomposition and to the momentum invariants. We explore the uniform and
soft-collinear infrared limits and obtain the expected infrared exponents. The
presence of a zero crossing in the tree-level component of the vertex is
confirmed for both scaling- and decoupling-type scenarios. The zero crossing
appears at a scale ~1 GeV; however, its location might be sensitive to the
four-gluon vertex and missing components in the DSE.


title: Fine tuning in small and large tan beta regions in the cE6SSM

abstract:
  The Electroweak sector in E6 supersymmetric models is subject to a degree of
fine tuning in the percent to permil level. This can be attributed to the
experimental limits on both the mass of the Z' boson associated with the extra
U(1)' symmetry in the model, as well as the masses of naturalness-related
sparticles (which is a general source of tuning in supersymmetric models). The
degree of tuning can be smaller than that in the minimal supersymmetric
standard model with universal fundamental parameters (the constrained MSSM). We
show this by quantifying the fine tuning in regions of the parameter space of
the constrained exceptional supersymmetric standard model (cE6SSM)
corresponding to values of tan beta below and above 10. It is found that, a
Higgs mass m_h ~ 125 GeV, a gluino mass ~ 1.5 TeV, and a Z' boson mass m_Z' ~
3.8 TeV correspond to fine tuning in the 0.2% (0.1%) level for tan beta = 30
(5).


title:
Characterization of the Intra-Unit-Cell magnetic order in
  Bi2Sr2CaCu2O8+d

abstract:
  As in YBa2Cu3O6+x and HgBa2CuO8+d, the pseudo-gap state in Bi2Sr2CaCu2O8+d is
characterized by the existence of an intra-unit-cell magnetic order revealed by
polarized neutron scattering technique. We report here a supplementary set of
polarized neutron scattering measurements for which the direction of the
magnetic moment is determined and the magnetic intensity is calibrated in
absolute units. The new data allow a close comparison between bilayer systems
YBa2Cu3O6+x and Bi2Sr2CaCu2O8+d and rise important questions concerning the
range of the magnetic correlations and the role of disorder around optimal
doping.


title: On-line secret sharing

abstract:
  In an on-line secret sharing scheme the dealer assigns shares in the order
the participants show up, knowing only those qualified subsets whose all
members she has seen. We assume that the overall access structure is known and
only the order of the participants is unknown. On-line secret sharing is a
useful primitive when the set of participants grows in time, and redistributing
the secret is too expensive. In this paper we start the investigation of
unconditionally secure on-line secret sharing schemes. The complexity of a
secret sharing scheme is the size of the largest share a single participant can
receive over the size of the secret. The infimum of this amount in the on-line
or off-line setting is the on-line or off-line complexity of the access
structure, respectively. For paths on at most five vertices and cycles on at
most six vertices the on-line and offline complexities are equal, while for
other paths and cycles these values differ. We show that the gap between these
values can be arbitrarily large even for graph based access structures. We
present a general on-line secret sharing scheme that we call first-fit. Its
complexity is the maximal degree of the access structure. We show, however,
that this on-line scheme is never optimal: the on-line complexity is always
strictly less than the maximal degree. On the other hand, we give examples
where the first-fit scheme is almost optimal, namely, the on-line complexity
can be arbitrarily close to the maximal degree. The performance ratio is the
ratio of the on-line and off-line complexities of the same access structure. We
show that for graphs the performance ratio is smaller than the number of
vertices, and for an infinite family of graphs the performance ratio is at
least constant times the square root of the number of vertices.


title: Cartan decomposition for complex loop groups

abstract:
  In this note we formulate and prove a version of Cartan decomposition for
holomorphic loop groups, similar to Cartan decomposition for $p$-adic loop
groups, discussed proved by Garland (and later by the authors by geometric
mathods). The main technical tool that we use is the (well-known)
interpretation of twisted conjugacy classes in the holomorphic loop group in
terms of principal holomorphic bundles on an elliptic curve.


title: Prompt production of D mesons with ALICE at the LHC

abstract:
  This is a brief summary of prompt production of D mesons in pp and Pb-Pb
collisions with the ALICE apparatus at the LHC.


title:
Quantile Representation for Indirect Immunofluorescence Image
  Classification

abstract:
  In the diagnosis of autoimmune diseases, an important task is to classify
images of slides containing several HEp-2 cells. All cells from one slide share
the same label, and by classifying cells from one slide independently, some
information on the global image quality and intensity is lost. Considering one
whole slide as a collection (a bag) of feature vectors, however, poses the
problem of how to handle this bag. A simple, and surprisingly effective,
approach is to summarize the bag of feature vectors by a few quantile values
per feature. This characterizes the full distribution of all instances, thereby
assuming that all instances in a bag are informative. This representation is
particularly useful when each bag contains many feature vectors, which is the
case in the classification of the immunofluorescence images. Experiments on the
classification of indirect immunofluorescence images show the usefulness of
this approach.


title:
Density-Functional Theory and Tight-Binding Studies of the Geometry of
  Hydrogen Adsorbed on Graphynes

abstract:
  Using density-functional theory and a tight-binding approach we investigate
the physical origin of distinct favourable geometries of adsorbed hydrogen
atoms in various graphyne structures, and the relation with electronic
properties. In particular, H atoms are adsorbed in-plane for $\alpha$-graphyne,
and they assume an oblique configuration in all other graphynes, including
6,6,12-graphyne. The origin of different configurations is identified by means
of a simple tight-binding model and it is controlled by the tuning of the
hopping between sp$^2$-bonded C atoms and sp-bonded C atoms hybridized with the
H atoms. We discuss in details how the geometry change of the attached H atom
tunes the electronic properties like energy gap.


title:
Calibration artefacts in radio interferometry. I. Ghost sources in WSRT
  data

abstract:
  This work investigates a particular class of artefacts, or ghost sources, in
radio interferometric images. Earlier observations with (and simulations of)
the Westerbork Synthesis Radio Telescope (WSRT) suggested that these were due
to calibration with incomplete sky models. A theoretical framework is derived
that validates this suggestion, and provides predictions of ghost formation in
a two-source scenario. The predictions are found to accurately match the result
of simulations, and qualitatively reproduce the ghosts previously seen in
observational data. The theory also provides explanations for many previously
puzzling features of these artefacts (regular geometry, PSF-like sidelobes,
seeming independence on model flux), and shows that the observed phenomenon of
flux suppression affecting unmodelled sources is due to the same mechanism. We
demonstrate that this ghost formation mechanism is a fundamental feature of
calibration, and exhibits a particularly strong and localized signature due to
array redundancy. To some extent this mechanism will affect all observations
(including those with non-redundant arrays), though in most cases the ghosts
remain hidden below the noise or masked by other instrumental artefacts. The
implications of such errors on future deep observations are discussed.


title: Quantum Anomalous Hall Insulator of Composite Fermions

abstract:
  We show that a weak hexagonal periodic potential could transform a
two-dimensional electron gas with an even-denominator magnetic filling factor
to a quantum anomalous Hall insulator of composite fermions, giving rise to
fractionally quantized Hall effect. The system provides a realization of the
Haldane honeycomb-net model, albeit in a composite fermion system. We further
propose a trial wave function for the state, and numerically evaluate its
relative stability against the competing Hofstadter state. Possible sets of
experimental parameters are proposed.


title: Synchronization of two self-excited double pendula

abstract:
  We consider the synchronization of two self-excited double pendula. We show
that such pendula hanging on the same beam can have four different synchronous
configurations. Our approximate analytical analysis allows us to derive the
synchronization conditions and explain the observed types of synchronization.
We consider an energy balance in the system and describe how the energy is
transferred between the pendula via the oscillating beam, allowing thus the
pendula synchronization. Changes and stability ranges of the obtained solutions
with increasing and decreasing masses of the pendula are shown using
path-following.


title: Super/Subradiant Second Harmonic Generation

abstract:
  A scheme for active second harmonics generation is suggested. The system
comprises $N$ three-level atoms in ladder configuration, situated into resonant
cavity. It is found that the system can lase in either superradiant or
subradiant regime, depending on the number of atoms $N$. When N passes some
critical value the transition from the super to subradiance occurs in a
phase-transition-like manner. Stability study of the steady state supports this
conclusion.


title: Reasoning about Games via a First-order Modal Model Checking Approach

abstract:
  In this work, we present a logic based on first-order CTL, namely Game
Analysis Logic (GAL), in order to reason about games. We relate models and
solution concepts of Game Theory as models and formulas of GAL, respectively.
Precisely, we express extensive games with perfect in- formation as models of
GAL, and Nash equilibrium and subgame perfect equilibrium by means of formulas
of GAL. From a practical point of view, we provide a GAL model checker in order
to analyze games automatically. We use our model checker in at least two
directions: to find solution con- cepts of Game Theory; and, to analyze players
that are based on standard algorithms of the AI community, such as the minimax
procedure.


title:
Three New Cool Brown Dwarfs Discovered with the Wide-field Infrared
  Survey Explorer (WISE) and an Improved Spectrum of the Y0 Dwarf WISE
  J041022.71+150248.4

abstract:
  As part of a larger search of Wide-field Infrared Survey Explorer (WISE) data
for cool brown dwarfs with effective temperatures less than 1000 K, we present
the discovery of three new cool brown dwarfs with spectral types later than T7.
Using low-resolution, near-infrared spectra obtained with the NASA Infrared
Telescope Facility and the Hubble Space Telescope we derive spectral types of
T9.5 for WISE J094305.98+360723.5, T8 for WISE J200050.19+362950.1, and Y0: for
WISE J220905.73+271143.9. The identification of WISE J220905.73+271143.9 as a Y
dwarf brings the total number of spectroscopically confirmed Y dwarfs to
seventeen. In addition, we present an improved spectrum (i.e. higher
signal-to-noise ratio) of the Y0 dwarf WISE J041022.71+150248.4 that confirms
the Cushing et al. classification of Y0. Spectrophotometric distance estimates
place all three new brown dwarfs at distances less than 12 pc, with WISE
J200050.19+362950.1 lying at a distance of only 3.9-8.0 pc. Finally, we note
that brown dwarfs like WISE J200050.19+362950.1 that lie in or near the
Galactic plane offer an exciting opportunity to measure their mass via
astrometric microlensing.


title:
A Three-Phase Search Approach for the Quadratic Minimum Spanning Tree
  Problem

abstract:
  Given an undirected graph with costs associated with each edge as well as
each pair of edges, the quadratic minimum spanning tree problem (QMSTP)
consists of determining a spanning tree of minimum total cost. This problem can
be used to model many real-life network design applications, in which both
routing and interference costs should be considered. For this problem, we
propose a three-phase search approach named TPS, which integrates 1) a
descent-based neighborhood search phase using two different move operators to
reach a local optimum from a given starting solution, 2) a local optima
exploring phase to discover nearby local optima within a given regional search
area, and 3) a perturbation-based diversification phase to jump out of the
current regional search area. Additionally, we introduce dedicated techniques
to reduce the neighborhood to explore and streamline the neighborhood
evaluations. Computational experiments based on hundreds of representative
benchmarks show that TPS produces highly competitive results with respect to
the best performing approaches in the literature by improving the best known
results for 31 instances and matching the best known results for the remaining
instances only except two cases. Critical elements of the proposed algorithms
are analyzed.


title:
Adaptive ABC model choice and geometric summary statistics for hidden
  Gibbs random fields

abstract:
  Selecting between different dependency structures of hidden Markov random
field can be very challenging, due to the intractable normalizing constant in
the likelihood. We answer this question with approximate Bayesian computation
(ABC) which provides a model choice method in the Bayesian paradigm. This comes
after the work of Grelaud et al. (2009) who exhibited sufficient statistics on
directly observed Gibbs random fields. But when the random field is latent, the
sufficiency falls and we complement the set with geometric summary statistics.
The general approach to construct these intuitive statistics relies on a
clustering analysis of the sites based on the observed colors and plausible
latent graphs. The efficiency of ABC model choice based on these statistics is
evaluated via a local error rate which may be of independent interest. As a
byproduct we derived an ABC algorithm that adapts the dimension of the summary
statistics to the dataset without distorting the model selection.


title: On F and E, in DFT

abstract:
  Rigorous mathematical foundations of density functional theory are revisited,
with some use of infinitesimal (nonstandard) methods. A thorough treatment is
given of basic properties of internal energy and ground-state energy
functionals along with several improvements and clarifications of known
results.A simple metrizable topology is constructed on the space of densities
using a hierarchy of spatial partitions. This topology is very weak, but
supplemented by control of internal energy, it is, in a rough sense,
essentially as strong as $L^1$. Consequently, the internal energy functional
$F$ is lower semicontinuous with respect to it. With separation of positive and
negative parts of external potentials, very badly behaved, even infinite,
positive parts can be handled. Confining potentials are thereby incorporated
directly into the density functional framework.


title:
Representations of quasiprojective groups, Flat connections and
  Transversely projective foliations

abstract:
  The main purpose of this paper is to provide a structure theorem for
codimension one singular transversely projective foliationson projective
manifolds. To reach our goal, we firstly extend Corlette-Simpson's
classification of rank two representationsof fundamental groups of
quasiprojective manifolds by dropping the hypothesis of quasi-unipotency at
infinity.Secondly we establish an analogue classification for rank two flat
meromorphic connections.In particular, we prove that a rank two flat
meromorphic connection with irregular singularities having non trivial
Stokesprojectively factors through a connection over a curve.


title:
A bijection between the irreducible k-shapes and the surjective pistols
  of height k-1

abstract:
  This paper constructs a bijection between irreducible $k$-shapes and
surjective pistols of height $k-1$, which carries the "free $k$-sites" to the
fixed points of surjective pistols. The bijection confirms a conjecture of
Hivert and Mallet (FPSAC 2011) that the number of irreducible $k$-shape is
counted by the Genocchi number $G_{2k}$.


title: Variational Free Energies for Compressed Sensing

abstract:
  We consider the variational free energy approach for compressed sensing. We
first show that the na\"ive mean field approach performs remarkably well when
coupled with a noise learning procedure. We also notice that it leads to the
same equations as those used for iterative thresholding. We then discuss the
Bethe free energy and how it corresponds to the fixed points of the approximate
message passing algorithm. In both cases, we test numerically the direct
optimization of the free energies as a converging sparse-estimationalgorithm.


title:
Masses, Decay Constants and Electromagnetic Form-factors with Twisted
  Boundary Conditions

abstract:
  Using Chiral Perturbation Theory at one-loop we analyze the consequences of
twisted boundary conditions. We point out that due to the broken Lorentz and
reflection symmetry a number of unexpected terms show up in the expressions. We
explicitly discuss the pseudo-scalar octet masses, axial-vector and
pseudo-scalar decay constants and electromagnetic form-factors. We show how the
Ward identities are satisfied using the momentum dependent masses and the
non-zero vacuum-expectation-values values for the electromagnetic (vector)
currents. Explicit expressions at one-loop are provided and an appendix
discusses the needed one-loop twisted finite volume integrals.


title:
Evolution of Reddit: From the Front Page of the Internet to a
  Self-referential Community?

abstract:
  In the past few years, Reddit -- a community-driven platform for submitting,
commenting and rating links and text posts -- has grown exponentially, from a
small community of users into one of the largest online communities on the Web.
To the best of our knowledge, this work represents the most comprehensive
longitudinal study of Reddit's evolution to date, studying both (i) how user
submissions have evolved over time and (ii) how the community's allocation of
attention and its perception of submissions have changed over 5 years based on
an analysis of almost 60 million submissions. Our work reveals an
ever-increasing diversification of topics accompanied by a simultaneous
concentration towards a few selected domains both in terms of posted
submissions as well as perception and attention. By and large, our
investigations suggest that Reddit has transformed itself from a dedicated
gateway to the Web to an increasingly self-referential community that focuses
on and reinforces its own user-generated image- and textual content over
external sources.


title: New examples of asymptotically good Kummer type towers

abstract:
  In this work, we give sufficient conditions in order to have finite
ramification locus in sequences of function fields defined by different kind of
Kummer extensions. These conditions can be easily implemented in a computer to
generate several examples. We present some new examples of asymptotically good
towers of Kummer type and we show that many known examples can be obtained from
our general results.


title: Recent progress in quantum simulation using superconducting circuits

abstract:
  Quantum systems are notoriously difficult to simulate with classical means.
Recently, the idea of using another quantum system - which is experimentally
more controllable - as a simulator for the original problem has gained
significant momentum. Amongst the experimental platforms studied as quantum
simulators, superconducting qubits are one of the most promising, due to
relative straightforward scalability, easy design, and integration with
standard electronics. Here I review the recent state-of-the art in the field
and the prospects for simulating systems ranging from relativistic quantum
fields to quantum many-body systems.


title:
Distributed Variational Inference in Sparse Gaussian Process Regression
  and Latent Variable Models

abstract:
  Gaussian processes (GPs) are a powerful tool for probabilistic inference over
functions. They have been applied to both regression and non-linear
dimensionality reduction, and offer desirable properties such as uncertainty
estimates, robustness to over-fitting, and principled ways for tuning
hyper-parameters. However the scalability of these models to big datasets
remains an active topic of research. We introduce a novel re-parametrisation of
variational inference for sparse GP regression and latent variable models that
allows for an efficient distributed algorithm. This is done by exploiting the
decoupling of the data given the inducing points to re-formulate the evidence
lower bound in a Map-Reduce setting. We show that the inference scales well
with data and computational resources, while preserving a balanced distribution
of the load among the nodes. We further demonstrate the utility in scaling
Gaussian processes to big data. We show that GP performance improves with
increasing amounts of data in regression (on flight data with 2 million
records) and latent variable modelling (on MNIST). The results show that GPs
perform better than many common models often used for big data.


title:
Zero viscosity and thermal diffusivity limit of the linearized
  compressible Navier-Stokes-Fourier equations in the half plane

abstract:
  We study the zero viscosity and heat conductivity limit of an initial
boundary problem for the linearized Navier-Stokes-Fourier equations of a
compressible viscous and heat conducting fluid in the half plane. We consider
the case that the viscosity and thermal diffusivity converge to zero at the
same order. The approximate solution of the linearized Navier-Stokes-Fourier
equations with inner and boundary expansion terms is analyzed formally first by
multiscale analysis. Then the pointwise estimates of the error terms of the
approximate solution are obtained by energy methods, thus establish the uniform
stability for the linearized Navier-Stokes-Fourier equations in the zero
viscosity and heat conductivity limit. This work is based on \cite{xy} and
generalize the results from isentropic case to the general compressible fluid
with thermal diffusive effect. Besides the viscous layer as in \cite{xy},
thermal layer appears and coupled with the viscous layer linearly.


title: Seismological Diagnostics for Solar-like Stars

abstract:
  The oscillations in solar like stars are described in terms of the phase
shifts of the eigenmodes from simple sine-waves. We discuss model fitting and
inversion techniques based on this representation. We analyse the periodic
signatures from the HeII ionisation zone and base of the convective envelope of
the CoRoT star HD49933.


title:
Stability conditions for preprojective algebras and root systems of
  Kac-Moody Lie algebras

abstract:
  The aim of this paper is to study the space of stability conditions on the
bounded derived category of nilpotent modules over the preprojective algebra
associated with a quiver without loops. We describe this space as a covering
space of some open set determined by the root system of the Kac-Moody Lie
algebra associated with the quiver.


title: On Categories associated to a Quasi-Hopf algebra

abstract:
  A quasi-Hopf algebra $H$ can be seen as a commutative algebra $A$ in the
centre $\mathcal Z(H-Mod)$ of $H-Mod$. We show that the category of $A$-modules
in $\mathcal Z(H-Mod)$ is equivalent (as a monoidal category) to $H-Mod$. This
can be regarded as a generalization of the structure theorem of Hopf bimodules
of a Hopf algebra to the quasi-Hopf setting.


title:
QED effects in scattering processes involving atomic bound states:
  Radiative recombination

abstract:
  The standard S-matrix formulation cannot generally be used in the treatment
of atomic scattering processes, involving bound-state QED effects, due to the
special type of singularity that can here appear. This type of singularity can
be handled by means of methods designed for structure calculations. It is
essentially a consequence of the optical theorem that similar techniques can be
applied also in scattering processes. The optical theorem for free particles
gives a relation between the effective Hamiltonian and the cross section, a
relation that is valid also when bound states are present. We have found that
the method with the Covariant-evolution-operator/Green's operator that we have
developed primarily for structure problems can here be applied in a rather
straightforward manner. The new procedure is demonstrated for the case of
radiative recombination.


title:
Spectral instability of symmetric shear flows in a two-dimensional
  channel

abstract:
  This paper concerns spectral instability of shear flows in the incompressible
Navier-Stokes equations with sufficiently large Reynolds number: $R\to \infty$.
It is well-documented in the physical literature, going back to Heisenberg,
C.C. Lin, Tollmien, Drazin and Reid, that generic plane shear profiles other
than the linear Couette flow are linearly unstable for sufficiently large
Reynolds number. In this work, we provide a complete mathematical proof of
these physical results. In the case of a symmetric channel flow, our analysis
gives exact unstable eigenvalues and eigenfunctions, showing that the solution
could grow slowly at the rate of $e^{t/\sqrt {\alpha R}}$, where $\alpha$ is
the small spatial frequency that remains between lower and upper marginal
stability curves: $\alpha_\mathrm{low}(R) \approx R^{-1/7}$ and
$\alpha_\mathrm{up}(R) \approx R^{-1/11}$. We introduce a new, operator-based
approach, which avoids to deal with matching inner and outer asymptotic
expansions, but instead involves a careful study of singularity in the critical
layers by deriving pointwise bounds on the Green function of the corresponding
Rayleigh and Airy operators.


title:
Effective algebraic degeneracy of entire curves in complements of smooth
  projective hypersurfaces

abstract:
  In this work, it is established that for a generic projective hypersurface
$H\subset\mathbb{P}^n(\mathbb{C})$ of degree $d\geq(5n)^2\,n^{n}$, any
holomorphic entire curve $f\colon\mathbb{C}\to\mathbb{P}^n(\mathbb{C})\setminus
H$ has its image contained in a proper algebraic subvariety
$Z\subsetneq\mathbb{P}^{n}(\mathbb{C})$, that does not depend on the curve $f$.
  Here generic means that the coefficients of the defining equation of $H$ have
to lie outside of a proper algebraic subvariety of the projective space of
coefficients of homogeneous polynomials of degree $d$ (that parametrizes the
algebraic hypersurface of degree $d$ in $\mathbb{P}^n(\mathbb{C})$).
  The proof closely follows the work of Diverio, Merker and Rousseau
(Diverio-Merker-Rousseau 2009), thus it is based on the strategy of Siu (Siu
2002, 2004) and techniques of Demailly (Demailly 1995, Diverio 2009) (already
adapted to the logarithmic setting by Dethloff and Lu in 2001). It also include
an improved adaptation of the contribution of Berczi (Berczi 2010).


title: Self-induced polar order of active Brownian particles in a harmonic trap

abstract:
  Hydrodynamically interacting active particles in an external harmonic
potential form a self-assembled fluid pump at large enough P\'eclet numbers.
Here, we give a quantitative criterion for the formation of the pump and show
that particle orientations align in the self-induced flow field in surprising
analogy to ferromagnetic order where the active P\'eclet number plays the role
of inverse temperature. The particle orientations follow a Boltzmann
distribution $\Phi(\mathbf{p}) \sim \exp(A p_z)$ where the ordering mean field
$A$ scales with active P\'eclet number and polar order parameter. The mean flow
field in which the particles' swimming directions align corresponds to a
regularized stokeslet with strength proportional to swimming speed. Analytic
mean-field results are compared with results from Brownian dynamics simulations
with hydrodynamic interactions included and are found to capture the
self-induced alignment very well.


title:
The deuterium fractionation of water on solar-system scales in
  deeply-embedded low-mass protostars

abstract:
  (Abridged) The water deuterium fractionation (HDO/H$_2$O abundance ratio) has
traditionally been used to infer the amount of water brought to Earth by
comets. Measuring this ratio in deeply-embedded low-mass protostars makes it
possible to probe the critical stage when water is transported from clouds to
disks in which icy bodies are formed. We present sub-arcsecond resolution
observations of HDO in combination with H$_2^{18}$O from the PdBI toward the
three low-mass protostars NGC 1333-IRAS 2A, IRAS 4A-NW, and IRAS 4B. The
resulting HDO/H$_2$O ratio is $7.4\pm2.1\times10^{-4}$ for IRAS 2A,
$19.1\pm5.4\times10^{-4}$ for IRAS 4A-NW, and $5.9\pm1.7\times10^{-4}$ for IRAS
4B. Derived ratios agree with radiative transfer models within a factor of 2-4
depending on the source. Our HDO/H$_2$O ratios for the inner regions (where
$T>100$ K) of four young protostars are only a factor of 2 higher than those
found for pristine, solar system comets. These small differences suggest that
little processing of water occurs between the deeply embedded stage and the
formation of planetesimals and comets.


title: WiFiPos: An In/Out-Door Positioning Tool

abstract:
  Geographical location solutions have a wide diversity of applications,
ranging from emergency services to access to tourist and entertainment
services. GPS (Global Positioning System) is the most widely used system for
outdoor areas. Since it requires a direct line of sight with the satellites, it
cannot be used indoors. For indoor positioning, the most commonly used
technology to calculate the position of mobile devices is Wi-Fi. In this
article, we present a positioning tool called WiFiPos based on Wi-Fi signal
processing. This tool uses different variations of the Fingerprint technique to
analyze the performance and accuracy of the system both indoors and outdoors.


title:
Dichotomy of Electronic Structure and Superconductivity between
  Single-Layer and Double-Layer FeSe/SrTiO3 Films

abstract:
  The latest discovery of possible high temperature superconductivity in the
single-layer FeSe film grown on a SrTiO3 substrate, together with the
observation of its unique electronic structure and nodeless superconducting
gap, has generated much attention. Initial work also found that, while the
single-layer FeSe/SrTiO3 film exhibits a clear signature of superconductivity,
the double-layer FeSe/SrTiO3 film shows an insulating behavior. Such a dramatic
difference between the single-layer and double-layer FeSe/SrTiO3 films is
surprising and the underlying origin remains unclear. Here we report our
comparative study between the single-layer and double-layer FeSe/SrTiO3 films
by performing a systematic angle-resolved photoemission study on the samples
annealed in vacuum. We find that, like the single-layer FeSe/SrTiO3 film, the
as-prepared double-layer FeSe/SrTiO3 film is insulating and possibly magnetic,
thus establishing a universal existence of the magnetic phase in the
FeSe/SrTiO3 films. In particular, the double-layer FeSe/SrTiO3 film shows a
quite different doping behavior from the single-layer film in that it is hard
to get doped and remains in the insulating state under an extensive annealing
condition. The difference originates from the much reduced doping efficiency in
the bottom FeSe layer of the double-layer FeSe/SrTiO3 film from the FeSe-SrTiO3
interface. These observations provide key insights in understanding the origin
of superconductivity and the doping mechanism in the FeSe/SrTiO3 films. The
property disparity between the single-layer and double-layer FeSe/SrTiO3 films
may facilitate to fabricate electronic devices by making superconducting and
insulating components on the same substrate under the same condition.


title: Generating a Cosmological Constant with Gravitational Waves

abstract:
  A technique is given to derive the well known Bell-Szekeres solution of the
Einstein-Maxwell vacuum field equations describing the space-time and the
Maxwell field following the head-on collision of two homogeneous, plane,
electromagnetic shock waves. The analogue of this technique is then utilized to
construct the space-time model of the gravitational field following the head-on
collision of two homogeneous, plane, gravitational shock waves. The latter
collision, which is followed by a pair of impulsive gravitational waves and a
pair of light like shells traveling away from each other, provides a mechanism
for generating a cosmological constant which may be important in the
theoretical description of dark energy.


title:
A numerical method for the quasi-incompressible
  Cahn-Hilliard-Navier-Stokes equations for variable density flows with a
  discrete energy law

abstract:
  In this paper, we investigate numerically a diffuse interface model for the
Navier-Stokes equation with fluid-fluid interface when the fluids have
different densities \cite{Lowengrub1998}. Under minor reformulation of the
system, we show that there is a continuous energy law underlying the system,
assuming that all variables have reasonable regularities. It is shown in the
literature that an energy law preserving method will perform better for
multiphase problems. Thus for the reformulated system, we design a $C^0$ finite
element method and a special temporal scheme where the energy law is preserved
at the discrete level. Such a discrete energy law (almost the same as the
continuous energy law) for this variable density two-phase flow model has never
been established before with $C^0$ finite element. A Newton's method is
introduced to linearise the highly non-linear system of our discretization
scheme. Some numerical experiments are carried out using the adaptive mesh to
investigate the scenario of coalescing and rising drops with differing density
ratio. The snapshots for the evolution of the interface together with the
adaptive mesh at different times are presented to show that the evolution,
including the break-up/pinch-off of the drop, can be handled smoothly by our
numerical scheme. The discrete energy functional for the system is examined to
show that the energy law at the discrete level is preserved by our scheme.


title: Z_2-graded Gelfand-Kirillov dimension of the Grassmann algebra

abstract:
  We consider the infinite dimensional Grassmann algebra E over a field F of
characteristic 0 or p, where p>2, and we compute its Z_2-graded
Gelfand-Kirillov dimension as a Z_2-graded PI-algebra.


title:
Development of High Precision Timing Counter Based on Plastic
  Scintillator with SiPM Readout

abstract:
  High-time-resolution counters based on plastic scintillator with silicon
photomultiplier (SiPM) readout have been developed for applications to high
energy physics experiments for which relatively large-sized counters are
required. We have studied counter sizes up to $120\times40\times5$ mm^3 with
series connection of multiple SiPMs to increase the sensitive area and thus
achieve better time resolution. A readout scheme with analog shaping and
digital waveform analysis is optimized to achieve the highest time resolution.
The timing performance is measured using electrons from a Sr-90 radioactive
source, comparing different scintillators, counter dimensions, and types of
near-ultraviolet sensitive SiPMs. As a result, a resolution of $\sigma =42 \pm
2$ ps at 1 MeV energy deposition is obtained for counter size $60\times 30
\times 5$ mm^3 with three SiPMs ($3\times3$ mm^2 each) at each end of the
scintillator. The time resolution improves with the number of photons detected
by the SiPMs. The SiPMs from Hamamatsu Photonics give the best time resolution
because of their high photon detection efficiency in the near-ultraviolet
region. Further improvement is possible by increasing the number of SiPMs
attached to the scintillator.


title: Partial correlation analysis: Applications for financial markets

abstract:
  The presence of significant cross-correlations between the synchronous time
evolution of a pair of equity returns is a well-known empirical fact. The
Pearson correlation is commonly used to indicate the level of similarity in the
price changes for a given pair of stocks, but it does not measure whether other
stocks influence the relationship between them. To explore the influence of a
third stock on the relationship between two stocks, we use a partial
correlation measurement to determine the underlying relationships between
financial assets. Building on previous work, we present a statistically robust
approach to extract the underlying relationships between stocks from four
different financial markets: the United States, the United Kingdom, Japan, and
India. This methodology provides new insights into financial market dynamics
and uncovers implicit influences in play between stocks. To demonstrate the
capabilities of this methodology, we (i) quantify the influence of different
companies and, by studying market similarity across time, present new insights
into market structure and market stability, and (ii) we present a practical
application, which provides information on the how a company is influenced by
different economic sectors, and how the sectors interact with each other. These
examples demonstrate the effectiveness of this methodology in uncovering
information valuable for a range of individuals, including not only investors
and traders but also regulators and policy makers.


title:
Quenched disorder forbids discontinuous transitions in nonequilibrium
  low-dimensional systems

abstract:
  Quenched disorder affects significantly the behavior of phase transitions.
The Imry-Ma-Aizenman-Wehr-Berker argument prohibits first-order or
discontinuous transitions and their concomitant phase coexistence in
low-dimensional equilibrium systems in the presence of random fields. Instead,
discontinuous transitions become rounded or even continuous once disorder is
introduced. Here we show that phase coexistence and first-order phase
transitions are also precluded in nonequilibrium low-dimensional systems with
quenched disorder: discontinuous transitions in two-dimensional systems with
absorbing states become continuous in the presence of quenched disorder. We
also study the universal features of this disorder-induced criticality and find
them to be compatible with the universality class of the directed percolation
with quenched disorder. Thus, we conclude that first-order transitions do not
exist in low-dimensional disordered systems, not even in genuinely
nonequilibrium systems with absorbing states.


title:
Nonperturbative shell-model interactions from the in-medium similarity
  renormalization group

abstract:
  We present the first ab initio construction of valence-space Hamiltonians for
medium-mass nuclei based on chiral two- and three-nucleon interactions using
the in-medium similarity renormalization group. When applied to the oxygen
isotopes, we find experimental ground-state energies are well reproduced,
including the flat trend beyond the drip line at 24O. Similarly, natural-parity
spectra in 21,22,23,24O are in agreement with experiment, and we present
predictions for excited states in 25,26O. The results exhibit a weak dependence
on the harmonic-oscillator basis parameter and reproduce spectroscopy within
the standard sd valence space.


title: Tunguska similar impacts and origin of life

abstract:
  The author suggests new vision of mechanism of initiation of life on the
planets after Tunguska similar impacts. This mechanism takes into consideration
not only incoming cosmic organic substance but also information, which is
connected to this substance. Mathematical metrics of atom of hydrogen is
deduced which may be used for pattern recognition algorithm. In accordance to
author's opinion, similar algorithm can promote evolution (transformation) of
inert organic substance into living substance. The fact of a survival of
vegetation after the Tunguska event is analyzed especially. Also the author
checked up his probably Tunguska meteorites by strong magnet. The presence of
magnetic substance was detected with concentration of 10-2 % during this test.


title:
Overlap of two Brownian trajectories: exact results for scaling
  functions

abstract:
  We consider two random walkers starting at the same time $t=0$ from different
points in space separated by a given distance $R$. We compute the average
volume of the space visited by both walkers up to time $t$ as a function of $R$
and $t$ and dimensionality of space $d$. For $d<4$, this volume, after proper
renormalization, is shown to be expressed through a scaling function of a
single variable $R/\sqrt{t}$. We provide general integral formulas for scaling
functions for arbitrary dimensionality $d<4$. In contrast, we show that no
scaling function exists for higher dimensionalities $d \geq 4$

categories: math-ph cond-mat.stat-mech math.MP physics.data-an


title:
The arrival of the frequent: how bias in genotype-phenotype maps can
  steer populations to local optima

abstract:
  Genotype-phenotype (GP) maps specify how the random mutations that change
genotypes generate variation by altering phenotypes, which, in turn, can
trigger selection. Many GP maps share the following general properties: 1) The
number of genotypes $N_G$ is much larger than the number of selectable
phenotypes; 2) Neutral exploration changes the variation that is accessible to
the population; 3) The distribution of phenotype frequencies $F_p=N_p/N_G$,
with $N_p$ the number of genotypes mapping onto phenotype $p$, is highly
biased: the majority of genotypes map to only a small minority of the
phenotypes. Here we explore how these properties affect the evolutionary
dynamics of haploid Wright-Fisher models that are coupled to a simplified and
general random GP map or to a more complex RNA sequence to secondary structure
map. For both maps the probability of a mutation leading to a phenotype $p$
scales to first order as $F_p$, although for the RNA map there are further
correlations as well. By using mean-field theory, supported by computer
simulations, we show that the discovery time $T_p$ of a phenotype $p$ similarly
scales to first order as $1/F_p$ for a wide range of population sizes and
mutation rates in both the monomorphic and polymorphic regimes. These
differences in the rate at which variation arises can vary over many orders of
magnitude. Phenotypic variation with a larger $F_p$ is therefore be much more
likely to arise than variation with a small $F_p$. We show, using the RNA
model, that frequent phenotypes (with larger $F_p$) can fix in a population
even when alternative, but less frequent, phenotypes with much higher fitness
are potentially accessible. In other words, if the fittest never `arrive' on
the timescales of evolutionary change, then they can't fix. We call this highly
non-ergodic effect the `arrival of the frequent'.


title:
Dynamics of Order Parameters near Stationary States in Superconductors
  with a Charge-Density Wave

abstract:
  We consider a simple model of a quasi-one-dimensional conductor in which two
order parameters (OP) may coexist, i.e., the superconducting OP $\Delta$ and
the OP $W$ that characterizes the amplitude of a charge-density wave (CDW). In
the mean field approximation we present equations for the matrix Green's
functions $G_{ik}$, where $i$ relates to the one of the two Fermi sheets and
$k$, operates in the Gor'kov-Nambu space. Using the solutions of these
equations, we find stationary states for different values of the parameter
describing the curvature of the Fermi surface, $\mu$, which can be varied,
e.g., by doping. It is established that in the interval $\mu_1<\mu<\mu_2$ the
self-consistency equations have a solution for coexisting OPs $\Delta$ and $W$.
However, this solution corresponds to a saddle point in the energy functional
$\Phi(\Delta, W)$, i.e., it is unstable. Stable states are: 1)the state with
the CDW at $\mu < \mu_{2}$; and 2) the purely superconducting state at
$\mu_1<\mu$. At $\mu<\mu_0$, the state 1) corresponds to a global minimum, and
at $\mu_0<\mu$, the state 2) has a lower energy, i.e., only the superconducting
state survives at large $\mu$. We study the dynamics of the variations
$\delta\Delta$ and $\delta W$ from these states in the collisionless limit. It
is characterized by two modes of oscillations, the fast and the slow one. The
fast mode is analogous to damped oscillations in conventional superconductors.
The frequency of slow modes depends on the curvature $\mu$ and is much smaller
than $2\Delta$ if the coupling constants for superconductivity and CDW are
close to each other. The considered model can be applied to high-$T_c$
superconductors where the parts of the Fermi surface near the `hot' spots may
be regarded as the considered two Fermi sheets. We also discuss relation of the
considered model to the simplest model for Fe-based pnictides.


title:
Variational Inference in Sparse Gaussian Process Regression and Latent
  Variable Models - a Gentle Tutorial

abstract:
  In this tutorial we explain the inference procedures developed for the sparse
Gaussian process (GP) regression and Gaussian process latent variable model
(GPLVM). Due to page limit the derivation given in Titsias (2009) and Titsias &
Lawrence (2010) is brief, hence getting a full picture of it requires
collecting results from several different sources and a substantial amount of
algebra to fill-in the gaps. Our main goal is thus to collect all the results
and full derivations into one place to help speed up understanding this work.
In doing so we present a re-parametrisation of the inference that allows it to
be carried out in parallel. A secondary goal for this document is, therefore,
to accompany our paper and open-source implementation of the parallel inference
scheme for the models. We hope that this document will bridge the gap between
the equations as implemented in code and those published in the original
papers, in order to make it easier to extend existing work. We assume prior
knowledge of Gaussian processes and variational inference, but we also include
references for further reading where appropriate.


title:
Magnetic domain-wall motion study under an electric field in a Finemet
  thin film on flexible substrate

abstract:
  Influence of applied in-plane elastic strains on the static magnetic
configuration of a 530 nm magnetostrictive FeCuNbSiB thin film. The in-plane
strains are induced via the application of a voltage to a piezoelectric
actuator on which the film/substrate system was glued. A quantitative
characterization of the voltage dependence of the induced-strain at the surface
of the film was performed using a digital image correlation technique. MFM
images at remanence (H=0 Oe and U=0 V) clearly reveal the presence of weak
stripe domains. The effect of the voltage-induced strain shows the existence of
a threshold value above, which the break of the stripe configuration set in.
For a maximum strain of exx~0.5*10-3 we succeed in destabilizing the stripes
configuration helping the setting up of a complete homogeneous magnetic
pattern.


title: Asymptotics of weighted random sums

abstract:
  In this paper we study the asymptotic behaviour of weighted random sums when
the sum process converges stably in law to a Brownian motion and the weight
process has continuous trajectories, more regular than that of a Brownian
motion. We show that these sums converge in law to the integral of the weight
process with respect to the Brownian motion when the distance between
observations goes to zero. The result is obtained with the help of fractional
calculus showing the power of this technique. This study, though interesting by
itself, is motivated by an error found in the proof of Theorem 4 in Corcuera,
J.M. Nualart, D., Woerner, J. H. C. (2006). Power variation of some integral
fractional processes, Bernoulli 12(4) 713-735.


title: Saturn Ring Seismology: Looking Beyond First Order Resonances

abstract:
  Some wave features found in the C-ring of Saturn appear to be excited by
resonances with normal mode oscillations of the planet. The waves are found at
locations in the rings where the ratio of orbital to oscillation frequencies is
given by m : m+1 where m is a small integer. I suggest here that it is
plausible that ring waves may also be launched at second order resonances,
where the frequency ratio would be m : m+2. Indeed, otherwise unassociated wave
features are found at such locations in the C-ring. If confirmed the
association of planetary modes with additional C-ring wave features would
measure additional oscillation frequencies of Saturn and improve the utility of
the waves for constraining the internal structure of the planet. Second-order
resonances in general do not lie near first order ring resonance locations and
thus are not the explanation for the apparent frequency splitting of modes.


title:
The Deffuant model on $\mathbb{Z}$ with higher-dimensional opinion
  spaces

abstract:
  When it comes to the mathematical modelling of social interaction patterns, a
number of different models have emerged and been studied over the last decade,
in which individuals randomly interact on the basis of an underlying graph
structure and share their opinions. A prominent example of the so-called
bounded confidence models is the one introduced by Deffuant et al.: Two
neighboring individuals will only interact if their opinions do not differ by
more than a given threshold $\theta$. We consider this model on the line graph
$\mathbb{Z}$ and extend the results that have been achieved for the model with
real-valued opinions by considering vector-valued opinions and general metrics
measuring the distance between two opinion values. Just as in the univariate
case, there exists a critical value for $\theta$ at which a phase transition in
the long-term behavior takes place.


title:
Estimates of the rate of approximation in the CLT for $L_1$-norm of
  density estimators

abstract:
  We provide estimates of the rate of strong approximation and bounds for
probabilities of moderate deviations in the CLT for the $L_1$-norm of the
kernel density estimator without any assumptions on the density and assuming
that the kernel is bounded and has bounded support.


title: Pre - Inflationary Clues from String Theory ?

abstract:
  "Brane supersymmetry breaking" occurs in String Theory when the only
available combinations of D-branes and orientifolds are not mutually BPS and
yet do not introduce tree-level tachyon instabilities. It is characterized by
the emergence of a steep exponential potential, and thus by the absence of
maximally symmetric vacua. The corresponding low-energy supergravity admits
intriguing spatially-flat cosmological solutions where a scalar field is forced
to climb up toward the steep potential after an initial singularity, and
additional milder terms can inject an inflationary phase during the ensuing
descent. We show that, in the resulting power spectra of scalar perturbations,
an infrared suppression is typically followed by a pre-inflationary peak that
reflects the end of the climbing phase and can lie well apart from the
approximately scale invariant profile. A first look at WMAP9 raw data shows
that, while the chi^2 fits for the low-l CMB angular power spectrum are clearly
compatible with an almost scale invariant behavior, they display nonetheless an
eye-catching preference for this type of setting within a perturbative string
regime.


title: Tabletop imaging of structural evolutions in chemical reactions

abstract:
  The introduction of femto-chemistry has made it a primary goal to follow the
nuclear and electronic evolution of a molecule in time and space as it
undergoes a chemical reaction. Using Coulomb Explosion Imaging we have shot the
first high-resolution molecular movie of a to and fro isomerization process in
the acetylene cation. So far, this kind of phenomenon could only be observed
using VUV light from a Free Electron Laser [Phys. Rev. Lett. 105, 263002
(2010)]. Here we show that 266 nm ultrashort laser pulses are capable of
initiating rich dynamics through multiphoton ionization. With our generally
applicable tabletop approach that can be used for other small organic
molecules, we have investigated two basic chemical reactions simultaneously:
proton migration and C=C bond-breaking, triggered by multiphoton ionization.
The experimental results are in excellent agreement with the timescales and
relaxation pathways predicted by new and definitively quantitative ab initio
trajectory simulations.


title:
Multidimensional Hungarian construction for vectors with almost Gaussian
  smooth distributions

abstract:
  A multidimensional version of the results of Koml\'os, Major and Tusn\'ady
for sums of independent random vectors with finite exponential moments is
obtained in the particular case where the summands have smooth distributions
which are close to Gaussian ones. The bounds obtained reflect this closeness.
Furthermore, the results provide sufficient conditions for the existence of
i.i.d. vectors $X_1, X_2,\dots$ with given distributions and corresponding
i.i.d. Gaussian vectors $Y_1, Y_2,\dots$ such that, for given small
$\varepsilon$, $$ {\mathbf P}\Big\{{\limsup\limits_{n\to\infty} \frac1{\log
n}\Bigl|\,\sum\limits_{j=1}^n X_j- \sum\limits_{j=1}^n Y_j\,\Bigr|}\le
\varepsilon\Big\}=1. $$


title:
An Explicit Bound for Dynamical Localisation in an Interacting Many-Body
  System

abstract:
  We characterise and study dynamical localisation of a finite interacting
quantum many-body system. We present explicit bounds on the disorder strength
required for the onset of localisation of the dynamics of arbitrary ensemble of
sites of the XYZ spin-1/2 model. We obtain these results using a novel form of
the fractional moment criterion, which we establish, together with a
generalisation of the self-avoiding walk representation of the system Green's
functions, called path-sums. These techniques are not specific to the XYZ model
and hold in a much more general setting. We further present bounds for two
observable quantities in the localised regime: the magnetisation of any
sublattice of the system as well as the linear magnetic response function of
the system. We confirm our results through numerical simulations.


title:
Temperature-induced Change in the Fermi Surface Topology in the Spin
  Density Wave Phase of Sr(Fe$_{1-x}$Co$_x$)$_2$As$_2$

abstract:
  We report electronic Raman scattering measurements of
Sr(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals in their magnetic - Spin Density
Wave (SDW) phase. The spectra display multiple, polarization-resolved SDW gaps
as expected in a band-folding itinerant picture for a multiband system. The
temperature dependence of the SDW gaps reveals an unusual evolution of the
reconstructed electronic structure with at least one gap being activated only
well below the magnetic SDW transition $T_N$. A comparison with temperature
dependent Hall measurements allows us to assign this activated behavior to a
change in the Fermi surface topology deep in the SDW phase, which we attribute
to the disappearance of a hole-like Fermi pocket. Our results highlight the
strong sensitivity of the low energy electronic structure to temperature in
iron-arsenide superconductors.


title:
Self-organization into quantized eigenstates of a classical wave driven
  particle

abstract:
  A growing number of dynamical situations involve the coupling of particles or
singularities with physical waves. In principle these situations are very far
from the wave-particle duality at quantum scale where the wave is probabilistic
by nature. Yet some dual characteristics were observed in a system where a
macroscopic droplet is guided by a pilot-wave it generates. Here we investigate
the behaviour of these entities when confined in a two-dimensional harmonic
potential well. A discrete set of stable orbits is observed, in the shape of
successive generalized Cassinian-like curves (circles, ovals, lemniscates,
trefoils...). Along these specific trajectories, the droplet motion is
characterized by a double quantization of the orbit spatial extent and of the
angular momentum. We show that these trajectories are intertwined with the
dynamical build-up of central wave-field modes. These dual self-organized modes
form a basis of eigenstates on which more complex motions are naturally
decomposed.


title: Possible measurement of P-states probability in the $^4$He nucleus

abstract:
  Using the experimental data on total {\it S}=1 transition cross-sections \,
for $^4$He$(\gamma,p)$$^3$H and $^4$He$(\gamma,n)$$^3$He reactions as the base,
the paper describes the possibility of measuring the probability of {\it
P}-states in the $^4$He nucleus. The {\it S}=1 transitions may originate from
$^3P_0$ states of the nucleus, or be the result of the spin-flip of the
final-state particle system from $^1S_0$, or $^5D_0$ states of the $^4$He
nucleus, and also as a result of the secondary effects. The analysis of the
experimental data has suggested the conclusion that within the statistical
error the ratio of the {\it S}=1 transition cross-sections in the collinear
geometry to reaction cross-sections at polar nucleon-exit angle
$\theta_N$=$90^{\circ}$ $\nu_p$ and $\nu_n$ in the photon energy range
22$\le$E$_{\gamma}$$\le$100 MeV is independent of the photon energy. This is in
agreement with the assumption that the {\it S}=1 transitions can originate from
$^3P_0$ states of the $^4$He nucleus. Average values of magnitude $\nu_p$ and
$\nu_n$ in the mentioned photon energy range are calculated
$\nu_p$=0.01$\pm$0.002 and $\nu_n$=0.015$\pm$0.003. The errors are statistical
only.


title: Towards a Characterization of Leaf Powers by Clique Arrangements

abstract:
  The class ${\cal L}_k$ of $k$-leaf powers consists of graphs $G=(V,E)$ that
have a $k$-leaf root, that is, a tree $T$ with leaf set $V$, where $xy \in E$,
if and only if the $T$-distance between $x$ and $y$ is at most $k$. Structure
and linear time recognition algorithms have been found for $2$-, $3$-, $4$-,
and, to some extent, $5$-leaf powers, and it is known that the union of all
$k$-leaf powers, that is, the graph class ${\cal L} = \bigcup_{k=2}^\infty
{\cal L}_k$, forms a proper subclass of strongly chordal graphs. Despite from
that, no essential progress has been made lately. In this paper, we use the new
notion of clique arrangements to suggest that leaf powers are a natural special
case of strongly chordal graphs. The clique arrangement ${\cal A}(G)$ of a
chordal graph $G$ is a directed graph that represents the intersections between
maximal cliques of $G$ by nodes and the mutual inclusion of these vertex
subsets by arcs. Recently, strongly chordal graphs have been characterized as
the graphs that have a clique arrangement without bad $k$-cycles for $k \geq
3$. We show that the clique arrangement of every graph of ${\cal L}$ is free of
bad $2$-cycles. The question whether this characterizes the class ${\cal L}$
exactly remains open.


title: Lepton flavour violation at high energies: the LHC and a Linear Collider

abstract:
  We discuss several manifestations of charged lepton flavour violation at high
energies. Focusing on a supersymmetric type I seesaw, considering constrained
and semi-constrained supersymmetry breaking scenarios, we analyse different
observables, both at the LHC and at a future Linear Collider. We further
discuss how the synergy between low- and high-energy observables can shed some
light on the underlying mechanism of lepton flavour violation.


title: The Black Hole Uncertainty Principle Correspondence

abstract:
  The Black Hole Uncertainty Principle correspondence proposes a connection
between the Uncertainty Principle on microscopic scales and black holes on
macroscopic scales. This is manifested in a unified expression for the Compton
wavelength and Schwarzschild radius. It is a natural consequence of the
Generalized Uncertainty Principle, which suggests corrections to the
Uncertainty Principle as the energy increases towards the Planck value. It also
entails corrections to the event horizon size as the black hole mass falls to
the Planck value, leading to the concept of a Generalized Event Horizon. One
implication of this is that there could be sub-Planckian black holes with a
size of order their Compton wavelength. Loop quantum gravity suggests the
existence of black holes with precisely this feature. The correspondence leads
to a heuristic derivation of the black hole temperature and suggests how the
Hawking formula is modified in the sub-Planckian regime.


title:
Representations of the ultrahyperbolic BMS group HB. III. Determination
  of the representations induced from finite little groups

abstract:
  The ordinary Bondi-Metzner-Sachs (BMS) group B is the common asymptotic
symmetry group of all asymptotically flat Lorentzian space-times. As such, B is
the best candidate for the universal symmetry group of General Relativity.
However, in studying quantum gravity, space-times with signatures other than
the usual Lorentzian one, and complex space-times, are frequently considered.
Generalisations of B appropriate to these other signatures have been defined
earlier. In particular, HB, a variant of BMS group appropriate to the
ultrahyperbolic signature (+,+,-,-), has been defined in a previous paper where
it was shown that all the strongly continuous unitary irreducible
representations (IRs) of HB can be obtained with the Wigner-Mackey's inducing
method and that all the little groups of HB are compact.Here we describe in
detail all the finite little groups of HB and we find all the IRs of HB induced
by them.


title: Checking the strict positivity of Kraus maps is NP-hard

abstract:
  Basic properties in Perron-Frobenius theory are strict positivity,
primitivityand irreducibility. Whereas for nonnegative matrices, these
properties are equivalent to elementary graph properties which can be checked
in polynomial time, we show that for Kraus maps- the noncommutative
generalization of stochastic matrices - checking strict positivity (whether the
map sends the cone to its interior) is NP-hard. The proof proceeds by reducing
to the latter problem the existence of a non-zero solution of a special system
of bilinear equations. The complexity of irreducibility and primitivity is also
discussed in the noncommutative setting.


title:
The Holographic Geometry of the Renormalization Group and Higher Spin
  Symmetries

abstract:
  We consider the Wilson-Polchinski exact renormalization group applied to the
generating functional of single-trace operators at a free-fixed point in
$d=2+1$ dimensions. By exploiting the rich symmetry structure of free field
theory, we study the geometric nature of the RG equations and the associated
Ward identities. The geometry, as expected, is holographic, with $AdS$
spacetime emerging correspondent with RG fixed points. The field theory
construction gives us a particular vector bundle over the $d+1$-dimensional RG
mapping space, called a jet bundle, whose structure group arises from the
linear orthogonal bi-local transformations of the bare fields in the path
integral. The sources for quadratic operators constitute a connection on this
bundle and a section of its endomorphism bundle. Recasting the geometry in
terms of the corresponding principal bundle, we arrive at a structure
remarkably similar to the Vasiliev theory, where the horizontal part of the
connection on the principal bundle is Vasiliev's higher spin connection, while
the vertical part (the Faddeev-Popov ghost) corresponds to the $S$-field. The
Vasiliev equations are then, respectively, the RG equations and the BRST
equations, with the RG beta functions encoding bulk interactions. Finally, we
remark that a large class of interacting field theories can be studied through
integral transforms of our results, and it is natural to organize this in terms
of a large $N$ expansion.


title: Innovation of Superparamagnetism in Lead Nanoparticles

abstract:
  This work reports, some of the features related to the room temperature
superparamagnetic behaviours of lead nanoparticles. Such behaviours have not
been discussed elaborately, in any literatures, so far. It is obvious from our
studies that the superparamagnetic behaviours of Pb nanoparticles are
surprising behaviours, since bulk Pb has diamagnetic behaviours. Hysteresis
curve from Vibrating Sample Magnetometer study of Pb nanopowder (metal) serves
some new observations. The successful calculations of values like magnetic
size, saturation magnetization, coercive field, and remanent magnetism confirm
its superparamagnetic nature and explore its potential application in various
industries. This work throws some light on and helps further research.


title:
Detecting Orientational Order in Model Systems by X-ray Cross
  Correlation Methods

abstract:
  We present the results of a computational X-ray cross correlation analysis
(XCCA) study on two dimensional polygonal model structures. We show how to
detect and identify the orientational order of such systems, demonstrate how to
eliminate the influence of the "computational box" on the XCCA results and
develop new correlation functions that reflect the sample's orientational order
only. For this purpose, we study the dependence of the correlation functions on
the number of polygonal clusters and wave vector transfer $q$ for various types
of polygons including mixtures of polygons and randomly placed particles. We
define an order parameter that describes the orientational order within the
sample. Finally, we determine the influence of detector noise and non-planar
wavefronts on the XCCA data which both appear to affect the results
significantly and have thus to be considered in real experiments.


title:
On the Richtmyer-Meshkov instability evolving from a deterministic
  multimode planar interface

abstract:
  We investigate the shock-induced turbulent mixing between a light and heavy
gas, where a Richtmyer-Meshkov instability (RMI) is initiated by a $\Ma = 1.5$
shock wave. The prescribed initial conditions define a deterministic multimode
interface perturbation between the gases, which can be imposed exactly for
different simulation codes and resolutions to allow for quantitative
comparison. Well-resolved large-eddy simulations are performed using two
different and independently developed numerical methods with the objective of
assessing turbulence structures, prediction uncertainties and convergence
behaviour. The two numerical methods differ fundamentally with respect to the
employed subgrid-scale regularisation, each representing state-of-the-art
approaches to RMI. Unlike previous studies the focus of the present
investigation is to quantify uncertainties introduced by the numerical method,
as there is strong evidence that subgrid-scale regularisation and truncation
errors may have a significant effect on the linear and non-linear stages of the
RMI evolution. Fourier diagnostics reveal that the larger energy containing
scales converge rapidly with increasing mesh resolution and thus are in
excellent agreement for the two numerical methods. Spectra of gradient
dependent quantities, such as enstrophy and scalar dissipation rate, show
stronger dependencies on the small-scale flow field structures in consequence
of truncation error effects, which for one numerical method are dominantly
dissipative and for the other dominantly dispersive.


title: Spatial separation and entanglement of identical particles

abstract:
  We reconsider the effect of indistinguishability on the reduced density
operator of the internal degrees of freedom (tracing out the spatial degrees of
freedom) for a quantum system composed of identical particles located in
different spatial regions. We explicitly show that if the spin measurements are
performed in disjoint spatial regions then there are no constraints on the
structure of the reduced state of the system. This implies that the statistics
of identical particles has no role from the point of view of separability and
entanglement when the measurements are spatially separated. We extend the
treatment to the case of n particles and show the connection with some recent
criteria for separability based on subalgebras of observables.


title: Modeling phase transition and metastable phases

abstract:
  We propose a model that describes phase transition including metastable
phases present in the van der Waals Equation of State (EoS). We introduce a
dynamical system that is able to depict the mass transfer between two phases,
for which equilibrium states are both metastable and stable states, including
mixtures. The dynamical system is then used as a relaxation source term in a
isothermal two-phase model. We use a Finite volume scheme (FV) that treats the
convective part and the source term in a fractional step way. Numerical results
illustrate the ability of the model to capture phase transition and metastable
states.


title: Bundle-based pruning in the max-plus curse of dimensionality free method

abstract:
  Recently a new class of techniques termed the max-plus curse of
dimensionality-free methods have been developed to solve nonlinear optimal
control problems. In these methods the discretization in state space is avoided
by using a max-plus basis expansion of the value function. This requires
storing only the coefficients of the basis functions used for representation.
However, the number of basis functions grows exponentially with respect to the
number of time steps of propagation to the time horizon of the control problem.
This so called "curse of complexity" can be managed by applying a pruning
procedure which selects the subset of basis functions that contribute most to
the approximation of the value function. The pruning procedures described thus
far in the literature rely on the solution of a sequence of high dimensional
optimization problems which can become computationally expensive.
  In this paper we show that if the max-plus basis functions are linear and the
region of interest in state space is convex, the pruning problem can be
efficiently solved by the bundle method. This approach combining the bundle
method and semidefinite formulations is applied to the quantum gate synthesis
problem, in which the state space is the special unitary group (which is
non-convex). This is based on the observation that the convexification of the
unitary group leads to an exact relaxation. The results are studied and
validated via examples.


title: Primordial Black Holes and Quantum Effects

abstract:
  Primordial black holes (PBHs) are of special interest because of the crucial
role of quantum effects in their formation and evaporation. This means that
they provide a unique probe of the early universe, high-energy physics and
quantum gravity. We highlight some recent developments in the subject,
including improved limits on the fraction of the Universe going into
evaporating PBHs in the mass range $10^{9} - 10^{17}$ g and the possibility of
using PBHs to probe a cosmological bounce.


title: Deployment of an Innovative Resource Choice Method for Process Planning

abstract:
  Designers, process planners and manufacturers naturally consider different
concepts for a same object. The stiffness of production means and the design
specification requirements mark out process planners as responsible of the
coherent integration of all constraints. First, this paper details an
innovative solution of resource choice, applied for aircraft manufacturing
parts. In a second part, key concepts are instanced for the considered
industrial domain. Finally, a digital mock up validates the solution viability
and demonstrates the possibility of an in-process knowledge capitalisation and
use. Formalising the link between Design and Manufacturing allows to hope
enhancements of simultaneous Product / Process developments.


title: The Picard rank conjecture for the Hurwitz spaces of degree up to five

abstract:
  We prove that the rational Picard group of the simple Hurwitz space
${\mathcal H}_{d,g}$ is trivial for $d$ up to five. We also relate the rational
Picard groups of the Hurwitz spaces to the rational Picard groups of the Severi
varieties of nodal curves on Hirzebruch surfaces.


title:
Are European equity markets efficient? New evidence from fractal
  analysis

abstract:
  Fractal analysis is carried out on the stock market indices of seven European
countries and the US. We find evidence of long range dependence in the log
return series of the Mibtel (Italy) and the PX Glob (Czech Republic). Long
range dependence implies that predictable patterns in the log returns do not
dissipate quickly, and may therefore produce potential arbitrage opportunities.
Therefore, these results are in contravention of the Efficient Market
Hypothesis. We show that correcting for short range dependence, or
prefiltering, may dispose of genuine long range dependence, suggesting that the
market is efficient in cases when it is not. Prefiltering does not reduce
significantly the power of the tests only for cases for which the Hurst
exponent (a measure of the long range dependence) lies well outside the
boundaries of no long range dependence. For borderline cases, the prefiltering
procedure reduces the power of the test. On the other hand, the absence of
prefiltering does not result in a test that is significantly oversized.


title:
The shape of expansion induced by a line with fast diffusion in
  Fisher-KPP equations

abstract:
  We establish a new property of Fisher-KPP type propagation in a plane, in the
presence of a line with fast diffusion. We prove that the line enhances the
asymptotic speed of propagation in a cone of directions. Past the critical
angle given by this cone, the asymptotic speed of propagation coincides with
the classical Fisher-KPP invasion speed. Several qualitative properties are
further derived, such as the limiting behaviour when the diffusion on the line
goes to infinity.


title: Bi containing multiferroic perovskite oxide thin films

abstract:
  In this work multiferroic thin films of Bi containing perovskite oxides are
discussed, where the driving force for ferroelectricity are the Bi3+ lone-pair
electrons. First, a brief introduction of Bi containing multiferroic perovskite
oxides will be presented to describe the mechanisms for establishing magnetic
and ferroelectric order in these compounds and some recent developments in this
field of research are reported. The second section addresses experimental
aspects of epitaxial thin film growth of BiMnO3, (Bi0.9La0.1)2NiMnO6 (BLNMO)
and BiFeO3 thin films by pulsed laser deposition. The third section is
dedicated to the physical properties of such films in terms of structural
characterization and the magnetic and ferroelectric properties and their
correlations in form of magnetoelectric coupling (MEC).


title: Rigid Quasilocal Frames

abstract:
  In this thesis, I examine in detail the properties of rigid quasilocal frames
(RQF), which have been proposed as a geometrically natural way to define
spatially extended reference frames in general relativity. I also explore their
usefulness, in particular, as a tool for constructing completely general
conservation laws that do not rely on the presence of spacetime symmetries and
include both matter and gravitational contributions without the need for any ad
hoc structures such as pseudotensors. In doing so, I show how the RQF approach
affords a deeper understanding of the nature of gravitational fluxes via the
equivalence principle. Finally, I apply the RQF formalism to explore
Ehrenfest's rotating disk paradox, a generalization of Archimedes' law to
curved spacetime, tidal interactions for Earth's and Jupiter's moons, and more.


title: The spin evolution of the pulsars with non-rigid core

abstract:
  We formulate a model of pulsar spin evolution (braking, inclination angle
evolution and radiative precession) taking into account the non-rigidity of
neutron star rotation. We discuss two simple limiting cases of this model and
show that the evolution of the inclination angle substantially depends on the
model of crust-core interaction. The non-rigidity of core rotation accelerates
the inclination angle evolution and makes all pulsars evolve to the orthogonal
state. The size of the effect depends on the amount of differentially rotating
matter and mechanism of its interaction with the rest of the star. Since the
rapid volution of the inclination angle apparently contradicts the
observational data, our results may be used as an additional test for the
theories of the cores of neutron stars.


title: Opsin vs opsin: new materials for biotechnological applications

abstract:
  The need of new diagnostic methods satisfying, as an early detection, a low
invasive procedure and a cost-efficient value, is orienting the technological
research toward the use of bio-integrated devices, in particular bio-sensors.
The set of know-why necessary to achieve this goal is wide, from biochemistry
to electronics and is summarized in an emerging branch of electronics, called
\textit{proteotronics}. Proteotronics is here here applied to state a
comparative analysis of the electrical responses coming from type-1 and type-2
opsins. In particular, the procedure is used as an early investigation of a
recently discovered family of opsins, the proteorhodopsins activated by blue
light, BPRs. The results reveal some interesting and unexpected similarities
between proteins of the two families, suggesting the global electrical response
are not strictly linked to the class identity.