title:
Angular momentum transport efficiency in post-main sequence low-mass
  stars

abstract:
  Context. Using asteroseismic techniques, it has recently become possible to
probe the internal rotation profile of low-mass (~1.1-1.5 Msun) subgiant and
red giant stars. Under the assumption of local angular momentum conservation,
the core contraction and envelope expansion occurring at the end of the main
sequence would result in a much larger internal differential rotation than
observed. This suggests that angular momentum redistribution must be taking
place in the interior of these stars. Aims. We investigate the physical nature
of the angular momentum redistribution mechanisms operating in stellar
interiors by constraining the efficiency of post-main sequence rotational
coupling. Methods. We model the rotational evolution of a 1.25 Msun star using
the Yale Rotational stellar Evolution Code. Our models take into account the
magnetic wind braking occurring at the surface of the star and the angular
momentum transport in the interior, with an efficiency dependent on the degree
of internal differential rotation. Results. We find that models including a
dependence of the angular momentum transport efficiency on the radial
rotational shear reproduce very well the observations. The best fit of the data
is obtained with an angular momentum transport coefficient scaling with the
ratio of the rotation rate of the radiative interior over that of the
convective envelope of the star as a power law of exponent ~3. This scaling is
consistent with the predictions of recent numerical simulations of the
Azimuthal Magneto-Rotational Instability. Conclusions. We show that an angular
momentum transport process whose efficiency varies during the stellar evolution
through a dependence on the level of internal differential rotation is required
to explain the observed post-main sequence rotational evolution of low-mass
stars.


title: On some subclasses of m-fold symmetric bi-univalent functions

abstract:
  In this work, we introduce two new subclasses
S_{{\Sigma}_{m}}({\alpha},{\lambda}) and S_{{\Sigma}_{m}}(\b{eta},{\lambda}) of
{\Sigma}_{m} consisting of analytic and m-fold symmetric bi-univalent functions
in the open unit disk U. Furthermore, for functions in each of the subclasses
introduced in this paper, we obtain the coefficient bounds for |a_{m+1}| and
|a_{2m+1}|.


title:
Deep Reinforcement Learning from Self-Play in Imperfect-Information
  Games

abstract:
  Many real-world applications can be described as large-scale games of
imperfect information. To deal with these challenging domains, prior work has
focused on computing Nash equilibria in a handcrafted abstraction of the
domain. In this paper we introduce the first scalable end-to-end approach to
learning approximate Nash equilibria without prior domain knowledge. Our method
combines fictitious self-play with deep reinforcement learning. When applied to
Leduc poker, Neural Fictitious Self-Play (NFSP) approached a Nash equilibrium,
whereas common reinforcement learning methods diverged. In Limit Texas Holdem,
a poker game of real-world scale, NFSP learnt a strategy that approached the
performance of state-of-the-art, superhuman algorithms based on significant
domain expertise.


title: Entanglement Enhanced Thermometry in the Detection of the Unruh Effect

abstract:
  We show how the use of entanglement can enhance the precision of the
detection of the Unruh effect with an accelerated probe. We use the
Unruh-DeWitt model of a two-level atom interacting relativistically with a
quantum field and treat the atom as an open quantum system to derive the master
equation governing its evolution. By means of quantum state discrimination, we
detect the accelerated motion of the atom by examining its time evolving state.
It turns out that the optimal strategy for the detection of the Unruh effect,
to which the accelerated atom is sensitive, involves letting the
atom-thermometer equilibrate with the thermal bath. However, introducing
initial entanglement between the detector and an external degree of freedom
leads to an enhancement of the sensitivity of the detector. Also, the maximum
precision is attained within finite time, before equilibration takes place.


title:
Fe dopant in ZnO: 2+ vs 3+ valency and ion-carrier s,p-d exchange
  interaction

abstract:
  Dopants of transition metal ions in II-VI semiconductors exhibit native 2+
valency. Despite this, 3+ or mixed 3+/2+ valency of iron ions in ZnO was
reported previously. Several contradictory mechanisms have been put forward for
explanation of this fact so far. Here, we analyze Fe valency in ZnO by
complementary theoretical and experimental studies. Our calculations within the
generalized gradient approximation (GGA+U) indicate that the Fe ion is a
relatively shallow donor. Its stable charge state is Fe2+ in ideal ZnO,
however, the high energy of the (+/0) transition level enhances the
compensation of Fe2+ to Fe3+ by non-intentional acceptors in real samples.
Using several experimental methods like electron paramagnetic resonance,
magnetometry, conductivity, excitonic magnetic circular dichroism and
magneto-photoluminescence we confirm the 3+ valency of the iron ions in
polycrystalline (Zn,Fe)O films with the Fe content attaining 0.2%.We find a
predicted increase of n-type conductivity upon the Fe doping with the Fe donor
ionization energy of 0.25 +/- 0.02 eV consistent with the results of
theoretical considerations. Moreover, our magnetooptical measurements confirm
the calculated non-vanishing s,p-d exchange interaction between band carriers
and localized magnetic moments of the Fe3+ ions in the ZnO, being so far an
unsettled issue.


title: Measure-Independent Freezing of Quantum Coherence

abstract:
  We find that all measures of coherence are frozen for an initial state in a
strictly incoherent channel if and only if the relative entropy of coherence is
frozen for the state. Our finding reveals the existence of measure-independent
freezing of coherence, and provides an entropy-based dynamical condition in
which the coherence of an open quantum system is totally unaffected by noise.


title:
Influence of the water content in protoplanetary discs on planet
  migration and formation

abstract:
  The temperature and density profiles of protoplanetary discs depend crucially
on the mass fraction of micrometre-sized dust grains and on their chemical
composition. A larger abundance of micrometre-sized grains leads to an overall
heating of the disc, so that the water ice line moves further away from the
star. An increase in the water fraction inside the disc, maintaining a fixed
dust abundance, increases the temperature in the icy regions of the disc and
lowers the temperature in the inner regions. Discs with a larger silicate
fraction have the opposite effect. Here we explore the consequence of the dust
composition and abundance for the formation and migration of planets. We find
that discs with low water content can only sustain outwards migration for
planets up to 4 Earth masses, while outwards migration in discs with a larger
water content persists up to 8 Earth masses in the late stages of the disc
evolution. Icy planetary cores that do not reach run-away gas accretion can
thus migrate to orbits close to the host star if the water abundance is low.
Our results imply that hot and warm super-Earths found in exoplanet surveys
could have formed beyond the ice line and thus contain a significant fraction
in water. These water-rich super-Earths should orbit primarily around stars
with a low oxygen abundance, where a low oxygen abundance is caused by either a
low water-to-silicate ratio or by overall low metallicity.


title: Quantum Monte Carlo Study of the Rabi-Hubbard Model

abstract:
  We study, using quantum Monte Carlo (QMC) simulations, the ground state
properties of a one dimensional Rabi-Hubbard model. The model consists of a
lattice of Rabi systems coupled by a photon hopping term between near neighbor
sites. For large enough coupling between photons and atoms, the phase diagram
generally consists of only two phases: a coherent phase and a compressible
incoherent one separated by a quantum phase transition (QPT). We show that, as
one goes deeper in the coherent phase, the system becomes unstable exhibiting a
divergence of the number of photons. The Mott phases which are present in the
Jaynes-Cummings-Hubbard model are not observed in these cases due to the
presence of non-negligible counter-rotating terms. We show that these two
models become equivalent only when the detuning is negative and large enough,
or if the counter-rotating terms are small enough.


title:
Thermodynamic conditions during growth determine the magnetic anisotropy
  in epitaxial thin-films of La$_{0.7}$Sr$_{0.3}$MnO$_{3}$

abstract:
  The suitability of a particular material for use in magnetic devices is
determined by the process of magnetization reversal/relaxation, which in turn
depends on the magnetic anisotropy. Therefore, designing new ways to control
magnetic anisotropy in technologically important materials is highly desirable.
Here we show that magnetic anisotropy of epitaxial thin-films of half-metallic
ferromagnet La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) is determined by the proximity
to thermodynamic equilibrium conditions during growth. We performed a series of
X-ray diffraction and ferromagnetic resonance (FMR) experiments in two
different sets of samples: the first corresponds to LSMO thin-films deposited
under tensile strain on (001) SrTiO$_{3}$ by Pulsed Laser Deposition (PLD; far
from thermodynamic equilibrium); the second were deposited by a slow Chemical
Solution Deposition (CSD) method, under quasi-equilibrium conditions. Thin
films prepared by PLD show a in-plane cubic anisotropy with an overimposed
uniaxial term. A large anisotropy constant perpendicular to the film plane was
also observed in these films. However, the uniaxial anisotropy is completely
suppressed in the CSD films. The out of plane anisotropy is also reduced,
resulting in a much stronger in plane cubic anisotropy in the chemically
synthesized films. This change is due to a different rotation pattern of
MnO$_{6}$ octahedra to accomodate epitaxial strain, which depends not only on
the amount of tensile stress imposed by the STO substrate, but also on the
growth conditions. Our results demonstrate that the nature and magnitude of the
magnetic anisotropy in LSMO can be tuned by the thermodynamic parameters during
thin-film deposition.


title: Diffeomorphism invariant cosmological symmetry in full quantum gravity

abstract:
  This paper summarizes a new proposal to define rigorously a sector of loop
quantum gravity at the diffeomorphism invariant level corresponding to
homogeneous and isotropic cosmologies, thereby enabling a detailed comparison
of results in loop quantum gravity and loop quantum cosmology. The key
technical steps we have completed are (a) to formulate conditions for
homogeneity and isotropy in a diffeomorphism covariant way on the classical
phase space of general relativity, and (b) to translate these conditions
consistently using well-understood techniques to loop quantum gravity. Some
additional steps, such as constructing a specific embedding of the Hilbert
space of loop quantum cosmology into a space of (distributional) states in the
full theory, remain incomplete. However, we also describe, as a proof of
concept, a complete analysis of an analogous embedding of homogeneous and
isotropic loop quantum cosmology into the quantum Bianchi I model of Ashtekar
and Wilson-Ewing. Details will appear in a pair of forthcoming papers.


title: A multipurpose information engine that can go beyond the Carnot limit

abstract:
  Motivated by the recent work by Mandal and Jarzynski on autonomous Maxwell
demon information engine, we have extended their model by introducing two
different heat baths. The system (demon) is coupled to a memory register (tape)
and a work source. The performance of the system depends on the interplay
between these two sources along with the heat baths.
  We have found the system can act as an engine, refrigerator or an eraser.
Even the combination of any two is possible in some parameter space. We have
achieved the efficiency of the engine is greater than Carnot limit. The
coefficient of performance of refrigerator also achieves larger than Carnot
limit.


title: Dissipative Long-Range Entanglement Generation between Electronic Spins

abstract:
  We propose a scheme for deterministic generation and long-term stabilization
of entanglement between two electronic spin qubits confined in spatially
separated quantum dots. Our approach relies on an electronic quantum bus,
consisting either of quantum Hall edge channels or surface acoustic waves, that
can mediate long-range coupling between localized spins over distances of tens
of micrometers. Since the entanglement is actively stabilized by dissipative
dynamics, our scheme is inherently robust against noise and imperfections.


title: $X(5568)$ and and its partner states

abstract:
  Stimulated by the recent observation of the $X(5568)$, we study the $X(5568)$
and its partners under the tetraquark scenario. In the framework of the
color-magnetic interaction, we estimate the masses of the partner states of the
$X(5568)$ and discuss their decay pattern, which provide valuable information
on the future experimental search of these states.


title:
The limitations of discrete-time approaches to continuous-time contagion
  dynamics

abstract:
  Continuous-time Markov process models of contagions are widely studied, not
least because of their utility in predicting the evolution of real-world
contagions and in formulating control measures. It is often the case, however,
that discrete-time approaches are employed to analyze such models or to
simulate them numerically. In such cases, time is discretized into uniform
steps and transition rates between states are replaced by transition
probabilities. In this paper, we illustrate potential limitations to this
approach. We show how discretizing time leads to a restriction on the values of
the model parameters that can accurately be studied. We examine numerical
simulation schemes employed in the literature, showing how synchronous-type
updating schemes can bias discrete-time formalisms when compared against
continuous-time formalisms. Event-based simulations, such as the Gillespie
algorithm, are proposed as optimal simulation schemes both in terms of
replicating the continuous-time process and computational speed. Finally, we
show how discretizing time can affect the value of the epidemic threshold for
large values of the infection rate and the recovery rate, even if the ratio
between the former and the latter is small.


title: On a generalization of Bourgain's tree index

abstract:
  For a Banach space $X$, a sequence of Banach spaces $(Y_n)$, and a Banach
space $Z$ with an unconditional basis, D. Alspach and B. Sari introduced a
generalization of a Bourgain tree called a $(\oplus_n Y_n)_Z$-tree in $X$.
These authors also prove that any separable Banach space admitting a $(\oplus_n
Y_n)_Z$-tree with order $\omega_1$ admits a subspace isomorphic to $(\oplus_n
Y_n)_Z$. In this paper we give two new proofs of this result.


title:
Relatedness of the Incidence Decay with Exponential Adjustment (IDEA)
  Model, "Farr's Law" and Compartmental Difference Equation SIR Models

abstract:
  Mathematical models are often regarded as recent innovations in the
description and analysis of infectious disease outbreaks and epidemics, but
simple models have been in use for projection of epidemic trajectories for more
than a century. We recently described a single equation model (the incidence
decay with exponential adjustment, or IDEA, model) that can be used for short
term forecasting. In the mid-19th century, Dr. William Farr developed a single
equation approach (Farr's law) for epidemic forecasting. We show here that the
two models are in fact identical, and can be expressed in terms of one another,
and also in terms of a susceptible-infectious-removed (SIR) compartmental model
with improving control. This demonstrates that the concept of the reproduction
number, R0, is implicit to Farr's (pre-microbial era) work, and also suggests
that control of epidemics, whether via behavior change or intervention, is as
integral to the natural history of epidemics as is the dynamics of disease
transmission.


title: Tropical variants of some complex analysis results

abstract:
  Tropical Nevanlinna theory studies value distribution of continuous piecewise
linear functions of a real variable. In this paper, we use the reasoning from
tropical Nevanlinna theory to present tropical counterparts of some classical
complex results related to Fermat type equations, Hayman conjecture and Bruck
conjecture.


title: Multilevel Sequential Monte Carlo Samplers for Normalizing Constants

abstract:
  This article considers the sequential Monte Carlo (SMC) approximation of
ratios of normalizing constants associated to posterior distributions which in
principle rely on continuum models. Therefore, the Monte Carlo estimation error
and the discrete approximation error must be balanced. A multilevel strategy is
utilized to substantially reduce the cost to obtain a given error level in the
approximation as compared to standard estimators. Two estimators are considered
and relative variance bounds are given. The theoretical results are numerically
illustrated for the example of identifying a parametrized permeability in an
elliptic equation given point-wise observations of the pressure.


title:
A spectral sequence for stratified spaces and configuration spaces of
  points

abstract:
  We construct a spectral sequence associated to a stratified space, which
computes the compactly supported cohomology groups of an open stratum in terms
of the compactly supported cohomology groups of closed strata and the reduced
cohomology groups of the poset of strata. Several familiar spectral sequences
arise as special cases. The construction is sheaf-theoretic and works both for
topological spaces and for the \'etale cohomology of algebraic varieties. As an
application we prove a very general representation stability theorem for
configuration spaces of points.


title:
Production of massless bottom jets in ppbar and pp collisions at
  next-to-leading order of QCD

abstract:
  We present predictions for the inclusive production of bottom jets in
proton-antiproton collisions at 1.96 TeV and proton-proton collisions at 7 TeV.
The bottom quark is considered massless. In this scheme, we find that at small
transverse momentum (p_T) the ratio of the next-to-leading order to the
leading-order cross section (K factor) is smaller than one. It increases with
increasing p_T and approaches one at larger p_T at a value depending
essentially on the choice of the renormalization scale. Adding non-perturbative
corrections obtained from PYTHIA Monte Carlo calculations leads to reasonable
agreement with experimental b-jet cross sections obtained by the CDF and the
CMS collaborations.


title:
The evolution of metallicity and metallicity gradients from z=2.7-0.6
  with KMOS3D

abstract:
  We present measurements of the [NII]/Ha ratio as a probe of gas-phase oxygen
abundance for a sample of 419 star-forming galaxies at z=0.6-2.7 from the
KMOS3D near-IR multi-IFU survey. The mass-metallicity relation (MZR) is
determined consistently with the same sample selection, metallicity tracer, and
methodology over the wide redshift range probed by the survey. We find good
agreement with long-slit surveys in the literature, except for the low-mass
slope of the relation at z~2.3, where this sample is less biased than previous
samples based on optical spectroscopic redshifts. In this regime we measure a
steeper slope than some literature results. Excluding the AGN contribution from
the MZR reduces sensitivity at the high mass end, but produces otherwise
consistent results. There is no significant dependence of the [NII]/Ha ratio on
SFR or environment at fixed redshift and stellar mass. The IFU data allow
spatially resolved measurements of [NII]/Ha, from which we can infer abundance
gradients for 180 galaxies, thus tripling the current sample in the literature.
The observed gradients are on average flat, with only 15 gradients
statistically offset from zero at >3sigma. We have modelled the effect of
beam-smearing, assuming a smooth intrinsic radial gradient and known seeing,
inclination and effective radius for each galaxy. Our seeing-limited
observations can recover up to 70% of the intrinsic gradient for the largest,
face-on disks, but only 30% for the smaller, more inclined galaxies. We do not
find significant trends between observed or corrected gradients and any stellar
population, dynamical or structural galaxy parameters, mostly in agreement with
existing studies with much smaller sample sizes. In cosmological simulations,
strong feedback is generally required to produce flat gradients at high
redshift.


title: Overdispersed Black-Box Variational Inference

abstract:
  We introduce overdispersed black-box variational inference, a method to
reduce the variance of the Monte Carlo estimator of the gradient in black-box
variational inference. Instead of taking samples from the variational
distribution, we use importance sampling to take samples from an overdispersed
distribution in the same exponential family as the variational approximation.
Our approach is general since it can be readily applied to any exponential
family distribution, which is the typical choice for the variational
approximation. We run experiments on two non-conjugate probabilistic models to
show that our method effectively reduces the variance, and the overhead
introduced by the computation of the proposal parameters and the importance
weights is negligible. We find that our overdispersed importance sampling
scheme provides lower variance than black-box variational inference, even when
the latter uses twice the number of samples. This results in faster convergence
of the black-box inference procedure.


title: Stochastic thermodynamics of resetting

abstract:
  Stochastic dynamics with random resetting leads to a non-equilibrium steady
state. Here, we consider the thermodynamics of resetting by deriving the first
and second law for reset processes far from equilibrium. We identify the
contributions to the entropy production of the system which arise due to
resetting and show that they correspond to the rate with which information is
either erased or created. Using Landauer's principle, we derive a bound on the
amount of work that is required to maintain a resetting process. We discuss
different regimes of resetting, including a Maxwell's demon scenario where heat
is extracted from a bath at constant temperature.


title:
Cantilever detected ferromagnetic resonance in thin Fe$_{50}$Ni$_{50}$,
  Co$_2$FeAl$_{0.5}$Si$_{0.5}$ and Sr$_2$FeMoO$_6$ films using a double
  modulation technique

abstract:
  In this work we introduce a new method of a ferromagnetic resonance (FMR)
detection from thin, nm-size, films. Our setup is based on the commercial
piezo-cantilever, used for atomic force microscopy. It has an option to rotate
the sample in the magnetic field and it operates up to the high microwave
frequencies of 160 GHz. Using our cantilever based FMR spectrometer we have
investigated a set of samples, namely quasi-bulk and 84 nm film
Co$_2$FeAl$_{0.5}$Si$_{0.5}$ samples, 16 nm Fe$_{50}$Ni$_{50}$ film and 150 nm
Sr$_2$FeMoO$_6$ film. The high frequency ferromagnetic resonance (FMR) response
from an extremely thin Fe$_{50}$Ni$_{50}$ film we have fitted with the
conventional model for the magnetization dynamics. The cantilever detected FMR
experiments on Sr$_2$FeMoO$_6$ film reveal an inability of the conventional
model to fit frequency and angular dependences with the same set of parameters,
which suggests that one has to take into account much more complicated nature
of the magnetization precession in the Sr$_2$FeMoO$_6$ at low temperatures and
high frequencies. Moreover, the complicated dynamics of the magnetization
apparent in all investigated samples is suggested by a drastic increase of the
linewidths with increasing microwave frequency, and by an emergence of the
second line with an opposite angular dependence.


title: Directed collective motion of bacteria under channel confinement

abstract:
  Dense suspensions of swimming bacteria are known to exhibit collective
behaviour arising from the interplay of steric and hydrodynamic interactions.
Unconfined suspensions exhibit transient, recurring vortices and jets, whereas
those confinedin circular domains may exhibit order in the form of a spiral
vortex. Here we show that confinement into a long and narrow macroscopic
`racetrack' geometry stabilises bacterial motion to form a steady
unidirectional circulation. This motion is reproduced in simulations of
discrete swimmers that reveal the crucial role that bacteria-driven fluid flows
play in the dynamics. In particular, cells close to the channel wall produce
strong flows which advect cells in the bulk against their swimming direction.
We examine in detail the transition from a disordered state to persistent
directed motion as a function of the channel width,and show that the width at
the crossover point is comparable to the typical correlation length of swirls
seen in the unbounded system. Our results shed light on the mechanisms driving
the collective behaviour of bacteria and other active matter systems, and
stress the importance of the ubiquitous boundaries found in natural habitats.


title: Ruling out the orbital decay of the WASP-43b

abstract:
  We present 15 new transit observations of the exoplanet WASP-43b in the
$i'$,$g'$, and $R$ filters with the 1.0-m telescopes of Las Cumbres Observatory
Global Telescope (LCOGT) Network and the IAC80 telescope. We combine our 15 new
light curves with 52 others from literature, to analyze homogeneously all the
available transit light curves of this exoplanet. By extending the time span of
the monitoring of the transits to more than $5~yr$, and by analyzing the
individual mid-times of 72 transits, we study the proposed shortening of the
orbital period of WASP-43b. We estimate that the times of transit are
well-matched by our updated ephemeris equation, using a constant orbital
period. We estimate an orbital period change rate no larger than $\dot{P}=-0.02
\pm 6.6~ms~yr^{-1}$, which is fully consistent with a constant period. Based on
the timing analysis, we discard stellar tidal dissipation factors
$Q_{*}<10^{5}$. In addition, with the modelling of the transits we update the
system parameters: $a/Rs=4.867(23)$, $i=82.11(10)^{\circ}$ and
$R_p/R_s=0.15942(41)$, noticing a difference in the relative size of the planet
between optical and NIR bands.


title:
Form factors and the dilatation operator in $\mathcal{N}=4$ super
  Yang-Mills theory and its deformations

abstract:
  In the first part of this thesis, we study form factors of general
gauge-invariant local composite operators in $\mathcal{N}=4$ super Yang-Mills
theory at various loop orders and for various numbers of external legs. We show
how to use on-shell methods for their calculation and in particular extract the
dilatation operator from the result. We also investigate the properties of the
corresponding remainder functions. Moreover, we extend on-shell diagrams, a
Gra{\ss}mannian integral formulation and an integrability-based construction
via R-operators to form factors, focussing on the chiral part of the
stress-tensor supermultiplet as an example. In the second part, we study the
$\beta$- and the $\gamma_i$-deformation, which were respectively shown to be
the most general supersymmetric and non-supersymmetric field-theory
deformations of $\mathcal{N}=4$ super Yang-Mills theory that are integrable at
the level of the asymptotic Bethe ansatz. For these theories, a new kind of
finite-size effect occurs, which we call prewrapping and which emerges from
double-trace structures that are required in the deformed Lagrangians. While
the $\beta$-deformation is conformal when the double-trace couplings are at
their non-trivial IR fixed points, the $\gamma_i$-deformation has running
double-trace couplings without fixed points, which break conformal invariance
even in the planar theory. Nevertheless, the $\gamma_i$-deformation allows for
highly non-trivial field-theoretic tests of integrability at arbitrarily high
loop orders.


title: A new method for the inversion of atmospheric parameters of A/Am stars

abstract:
  We present an automated procedure that derives simultaneously the effective
temperature $T_{eff}$, the surface gravity logg, the metallicity [Fe/H], and
the equatorial projected rotational velocity vsini for "normal" A and Am stars.
The procedure is based on the principal component analysis inversion method of
Paletou et al. (2015a). A sample of 322 high resolution spectra of F0-B9 stars,
retrieved from the Polarbase, SOPHIE, and ELODIE databases, were used to test
this technique with real data. We have selected the spectral region from
4400-5000\AA\ as it contains many metallic lines and the Balmer H$\beta$ line.
Using 3 datasets at resolving powers of R=42000, 65000 and 76000, about
6.6x$10^6$ synthetic spectra were calculated to build a large learning
database. The Online Power Iteration algorithm was applied to these learning
datasets to estimate the principal components (PC). The projection of spectra
onto the few PCs offered an efficient comparison metric in a low dimensional
space. The spectra of the well known A0- and A1-type stars, Vega and Sirius A,
were used as control spectra in the three databases. Spectra of other well
known A-type stars were also employed in order to characterize the accuracy of
the inversion technique. All observational spectra were inverted and
atmospheric parameters derived. After removal of a few outliers, the
PCA-inversion method appears to be very efficient in determining $T_{eff}$,
[Fe/H], and vsini for A/Am stars. The derived parameters agree very well with
previous determinations. Using a statistical approach, deviations of around 150
K, 0.35 dex, 0.15 dex, and 2 km/s were found for $T_{eff}$, logg, [Fe/H], and
vsini with respect to literature values for A-type stars. The PCA-inversion
proves to be a very fast, practical, and reliable tool for estimating stellar
parameters of FGK and A stars, and deriving effective temperatures of M stars.


title: Stellar evolution in the outer Galaxy

abstract:
  We investigate the distribution of different classes of spectroscopically
identified sources and theoretical models in the color-color diagrams (CCDs)
combining the near-infrared (NIR) and mid-infrared (MIR) data to develop a
method to classify Outer Galaxy sources detected with the Spitzer Space
Telescope (hereafter Spitzer) SMOG survey in the IRAC 3.6 and 8.0 micrometer
and MIPS 24 micrometer bands. We supplement the Spitzer data with the data from
other satellite and ground-based surveys. The main goal of our study is to
discover and characterize the population of intermediate- and low-mass young
stellar objects (YSOs) in the Outer Galaxy and use it to study star formation
in a significantly different environment than the Galaxy inside the solar
circle. Since the YSOs can be confused with evolved stars in the MIR, these
classes of objects need to be carefully separated. Here we present the initial
results of our analysis using the Ks-[8.0] vs. Ks-[24] CCD as an example. The
evolved stars separated from YSOs in the YSO selection process will be
investigated in detail in the follow-up study.


title: Effective photon mass from black-hole formation

abstract:
  We compute the value of effective photon mass $m_\gamma$ at one-loop level in
QED in the background of small ($10^{10}\,\text{g} \lesssim M \ll
10^{16}\,\text{g}$) spherically symmetric black hole in asymptotically flat
spacetime. This effect is associated with the modification of electron/positron
propagator in presence of event horizon. Physical manifestations of black-hole
environment are compared with those of hot neutral plasma. We estimate the
distance to the nearest black hole from the upper bound on $m_\gamma$ obtained
in the Coulomb-law test. We also find that corrections to electron mass $m_e$
and fine structure constant $\alpha$ at one-loop level in QED are negligible in
the weak gravity regime.


title:
Chern-Simons Theory with Complex Gauge Group on Seifert Fibred
  3-Manifolds

abstract:
  We consider Chern-Simons theory with complex gauge group and present a
complete non-perturbative evaluation of the path integral (the partition
function and certain expectation values of Wilson loops) on Seifert fibred
3-Manifolds. We use the method of Abelianisation. In certain cases the path
integral can be seen to factorize neatly into holomorphic and anti-holomorphic
parts. We obtain closed formulae of this factorization for the expectation
values of torus knots.


title: The Basilica Thompson group is not finitely presented

abstract:
  We show that the Basilica Thompson group introduced by Belk and Forrest is
not finitely presented, and in fact is not of type FP_2. The proof involves
developing techniques for proving non-simple connectedness of certain
subcomplexes of CAT(0) cube complexes.


title:
New Discoveries from the Arecibo 327 MHz Drift Pulsar Survey Radio
  Transient Search

abstract:
  We present Clusterrank, a new algorithm for identifying dispersed
astrophysical pulses. Such pulses are commonly detected from Galactic pulsars
and rotating radio transients (RRATs), which are neutron stars with sporadic
radio emission. More recently, isolated, highly dispersed pulses dubbed fast
radio bursts (FRBs) have been identified as the potential signature of an
extragalactic cataclysmic radio source distinct from pulsars and RRATs.
Clusterrank helped us discover 14 pulsars and 8 RRATs in data from the Arecibo
327 MHz Drift Pulsar Survey (AO327). The new RRATs have DMs in the range $23.5
- 86.6$ pc cm$^{-3}$ and periods in the range $0.172 - 3.901$ s. The new
pulsars have DMs in the range $23.6 - 133.3$ pc cm$^{-3}$ and periods in the
range $1.249 - 5.012$ s, and include two nullers and a mode-switching object.
We estimate an upper limit on the all-sky FRB rate of $10^5$ day$^{-1}$ for
bursts with a width of 10 ms and flux density $\gtrsim 83$ mJy. The DMs of all
new discoveries are consistent with a Galactic origin. In comparing statistics
of the new RRATs with sources from the RRATalog, we find that both sets are
drawn from the same period distribution. In contrast, we find that the period
distribution of the new pulsars is different from the period distributions of
canonical pulsars in the ATNF catalog or pulsars found in AO327 data by a
periodicity search. This indicates that Clusterrank is a powerful complement to
periodicity searches and uncovers a subset of the pulsar population that has so
far been underrepresented in survey results and therefore in Galactic pulsar
population models.


title: Strong exponent bounds for the local Rankin-Selberg convolution

abstract:
  Let $F$ be a non-Archimedean locally compact field. Let $\sigma$ and $\tau$
be finite-dimensional semisimple representations of the Weil-Deligne group of
$F$. We give strong upper and lower bounds for the Artin and Swan exponents of
$\sigma\otimes\tau$ in terms of those of $\sigma$ and $\tau$. We give a
different lower bound in terms of $\sigma\otimes\check\sigma$ and
$\tau\otimes\check\tau$. Using the Langlands correspondence, we obtain the
bounds for Rankin-Selberg exponents.


title: Line broadening and the solar opacity problem

abstract:
  The calculation of line widths constitutes theoretical and computational
challenges in the calculation of opacities of hot dense plasmas. Opacity models
use line broadening approximations that are untested at stellar interior
conditions. Moreover, calculations of atomic spectra of the sun, indicate a
large discrepancy in the K-shell line widths between several atomic codes and
the OP. In this work, the atomic code STAR is used to study the sensitivity of
solar opacities to line-broadening. Variations in the solar opacity profile,
due to an increase of the Stark widths resulting from discrepancies with OP,
are compared, in light of the solar opacity problem, with the required opacity
variations of the present day sun, as imposed by helioseismic and neutrino
observations. The resulting variation profile, is much larger than the
discrepancy between different atomic codes, agrees qualitatively with the
missing opacity profile, recovers about half of the missing opacity nearby the
convection boundary and has a little effect in the internal regions. Since it
is hard to estimate quantitatively the uncertainty in the Stark widths, we show
that an increase of all line widths by a factor of about 100 recovers
quantitatively the missing opacity. These results emphasize the possibility
that photoexcitation processes are not modeled properly, and more specifically,
highlight the need for a better theoretical characterization of the line
broadening phenomena at stellar interior conditions and of the uncertainty due
to the way it is implemented by atomic codes.


title:
Domain wall interactions due to vacuum Dirac field fluctuations in 2+1
  dimensions

abstract:
  We evaluate quantum effects due to a $2$-component Dirac field in $2+1$
space-time dimensions, coupled to domain-wall like defects with a smooth shape.
We show that those effects induce non trivial contributions to the
(shape-dependent) energy of the domain walls. For a single defect, we study the
divergences in the corresponding self-energy, and also consider the role of the
massless zero mode, corresponding to the Callan-Harvey mechanism, by coupling
the Dirac field to an external gauge field. For two defects, we show that the
Dirac field induces a non trivial, Casimir-like effect between them, and
provide an exact expression for that interaction in the case of two
straight-line parallel defects. As is the case for the Casimir interaction
energy, the result is finite and unambiguous.


title: Inferring causality from noisy time series data

abstract:
  Convergent Cross-Mapping (CCM) has shown high potential to perform causal
inference in the absence of models. We assess the strengths and weaknesses of
the method by varying coupling strength and noise levels in coupled logistic
maps. We find that CCM fails to infer accurate coupling strength and even
causality direction in synchronized time-series and in the presence of
intermediate coupling. We find that the presence of noise deterministically
reduces the level of cross-mapping fidelity, while the convergence rate
exhibits higher levels of robustness. Finally, we propose that controlled noise
injections in intermediate-to-strongly coupled systems could enable more
accurate causal inferences. Given the inherent noisy nature of real-world
systems, our findings enable a more accurate evaluation of CCM applicability
and advance suggestions on how to overcome its weaknesses.


title: A diffusion driven curvature flow

abstract:
  Bence-Merriman-Osher algorithm computes numerically mean curvature flow via
solutions of heat equation iteratively initialized at the end of each short
time interval. Inspired by the convergence proof of Evans of this algorithm
where he employed nonlinear semigroup theory and level set approach to mean
curvature flow, we prove here that a similar procedure, but now with a
different definition of evolved surface at the end of each short time interval,
results in a motion by curvature. The interest of this version of the algorithm
is its application corresponding to model of the visual cortex.


title:
Unconventional superconductivity and interaction induced Fermi surface
  reconstruction in the two-dimensional Edwards model

abstract:
  We study the competition between unconventional superconducting pairing and
charge density wave (CDW) formation for the two-dimensional Edwards Hamiltonian
at half filling, a very general two-dimensional transport model in which
fermionic charge carriers couple to a correlated background medium. Using the
projective renormalization method we find that a strong renormalization of the
original fermionic band causes a new hole-like Fermi surface to emerge near the
center of the Brillouin zone, before it eventually gives rise to the formation
of a charge density wave. On the new, disconnected parts of the Fermi surface
superconductivity is induced with a sign-changing order parameter. We discuss
these findings in the light of recent experiments on iron-based oxypnictide
superconductors.


title: Spectral Kurtosis Statistics of Transient Signals

abstract:
  We obtain analytical approximations for the expectation and variance of the
Spectral Kurtosis estimator in the case of Gaussian and coherent transient time
domain signals mixed with a quasi-stationary Gaussian background, which are
suitable for practical estimations of their signal-to-noise ratio and
duty-cycle relative to the instrumental integration time. We validate these
analytical approximations by means of numerical simulations and demonstrate
that such estimates are affected by statistical uncertainties that, for a
suitable choice of the integration time, may not exceed a few percent. Based on
these analytical results, we suggest a multiscale Spectral Kurtosis
spectrometer design optimized for real-time detection of transient signals,
automatic discrimination based on their statistical signature, and measurement
of their properties.


title:
Variational estimation of the drift for stochastic differential
  equations from the empirical density

abstract:
  We present a method for the nonparametric estimation of the drift function of
certain types of stochastic differential equations from the empirical density.
It is based on a variational formulation of the Fokker-Planck equation. The
minimization of an empirical estimate of the variational functional using
kernel based regularization can be performed in closed form. We demonstrate the
performance of the method on second order, Langevin-type equations and show how
the method can be generalized to other noise models.


title: Long-range synchrony and emergence of reentry in neural networks

abstract:
  Synchronization across long neural distances is a functionally important
phenomenon. In order to access the mechanistic basis of long-range synchrony,
we constructed an experimental model that enables monitoring of spiking
activities over centimeter scale distances in large random networks of cortical
neutrons. We show that the mode of synchrony over these distances depends upon
a length scale, $\lambda$, which is the minimal path that activity should
travel through before meeting its point of origin ready for reactivation. When
$\lambda$ is experimentally made larger than the physical dimension of the
network, distant neuronal populations operate synchronously, giving rise to
irregularly occurring network-wide events that last hundreds of milliseconds to
couple of seconds. In contrast, when $\lambda$ approaches the dimension of the
network, a continuous self-sustained reentry propagation emerges, a regular
dynamical mode that is marked by precise spatiotemporal patterns (`synfire
chains') that may last many minutes. These results contribute to discussions on
the origin of different modes of neural synchrony in normal and pathological
conditions


title:
Precise Pointing and Stabilization Performance for the Balloon-borne
  Imaging Testbed (BIT): 2015 Test Flight

abstract:
  Balloon-borne astronomy offers an attractive option for experiments that
require precise pointing and attitude stabilization, due to a large reduction
in the atmospheric interference observed by ground-based systems as well as the
low-cost and short development time-scale compared to space-borne systems. The
Balloon-borne Imaging Testbed (BIT) is an instrument designed to meet the
technological requirements of high precision astronomical missions and is a
precursor to the development of a facility class instrument with capabilities
similar to the Hubble Space Telescope. The attitude determination and control
systems (ADCS) for BIT, the design, implementation, and analysis of which are
the focus of this paper, compensate for compound pendulation effects and other
sub-orbital disturbances in the stratosphere to within 1-2$^{\prime\prime}$
(rms), while back-end optics provide further image stabilization down to
0.05$^{\prime\prime}$ (not discussed here). During the inaugural test flight
from Timmins, Canada in September 2015, BIT ADCS pointing and stabilization
performed exceptionally, with coarse pointing and target acquisition to within
< 0.1$^\circ$ and fine stabilization to 0.68$^{\prime\prime}$ (rms) over long
(10-30 minute) integrations. This level of performance was maintained during
flight for several tracking runs that demonstrated pointing stability on the
sky for more than an hour at a time. To refurbish and improve the system for
the three-month flight from New Zealand in 2018, certain modifications to the
ADCS need to be made to smooth pointing mode transitions and to correct for
internal biases observed during the test flight. Furthermore, the level of
autonomy must be increased for future missions to improve system reliability
and robustness.


title:
Isotopic yield in cold binary fission of even-even $^{244-258}$Cf
  isotopes

abstract:
  The cold binary fission of even-even 244-258Cf isotopes has been studied by
taking the interacting barrier as the sum of Coulomb and proximity potential.
The favorable fragment combinations are obtained from the cold valley plot
(plot of driving potential vs. mass number of fragments) and by calculating the
yield for charge minimized fragments. It is found that highest yield for
244,246,248Cf isotopes are for the fragments with isotope of Pb (Z=82) as one
fragment, whereas for 250Cf and 252Cf isotopes the highest yield is for the
fragments with isotope of Hg (Z=80) as one fragment. In the case of
254,256,258Cf isotopes the highest yield is for the fragments with Sn (Z=50) as
one fragment. Thus, the fragment combinations with maximum yield reveal the
role of doubly magic and near doubly magic nuclei in binary fission. It is
found that asymmetric splitting is favoured for Cf isotopes with mass number A
< 250 and symmetric splitting is favoured for Cf isotopes with A > 252. In the
case of Cf isotope with A=252, there is an equal probability for asymmetric and
symmetric splitting. The individual yields obtained for the cold fission of
252Cf isotope are compared with the experimental data taken from the {\gamma}-
{\gamma}- {\gamma} coincidences technique using Gammasphere.


title: 28 SiO v=0 J=1-0 emission from evolved stars

abstract:
  Observations of 28SiO v=0 J=1-0 line emission (7-mm wavelength) from AGB
stars show in some cases peculiar profiles, composed of a central intense
component plus a wider plateau. Very similar profiles have been observed in CO
lines from some AGB stars and most post-AGB nebulae and, in these cases, they
are clearly associated with the presence of conspicuous axial symmetry and
bipolar dynamics.
  We present systematic observations of 28SiO v=0 J=1-0 emission in 28 evolved
stars, performed with the 40~m radio telescope of the IGN in Yebes, Spain. We
find that the composite core plus plateau profiles are almost always present in
O-rich Miras, OH/IR stars, and red supergiants. They are also found in one
S-type Mira ($\chi$ Cyg), as well as in two semiregular variables (X Her and RS
Cnc) that are known to show axial symmetry. In the other objects, the profiles
are simpler and similar to those of other molecular lines. The composite
structure appears in the objects in which SiO emission is thought to come from
the very inner circumstellar layers, prior to dust formation. The central
spectral feature is found to be systematically composed of a number of narrow
spikes, except for X Her and RS Cnc, in which it shows a smooth shape that is
very similar to that observed in CO emission. These spikes show a significant
(and mostly chaotic) time variation, while in all cases the smooth components
remain constant within the uncertainties. The profile shape could come from the
superposition of standard wide profiles and a group of weak maser spikes.
Alternatively, we speculate that the very similar profiles detected in objects
that are axisymmetric may be indicative of the systematic presence of a
significant axial symmetry in the very inner circumstellar shells around AGB
stars; the presence of such symmetry would be independent of the probable weak
maser effects in the central spikes.


title:
Measurement of collective excitations in VO$_2$ by resonant inelastic
  X-ray scattering

abstract:
  Vanadium dioxide is of broad interest as a spin-1/2 electron system that
realizes a metal-insulator transition near room temperature, due to a
combination of strongly correlated and itinerant electron physics. Here,
resonant inelastic X-ray scattering is used to measure the excitation spectrum
of charge, spin, and lattice degrees of freedom at the vanadium L-edge under
different polarization and temperature conditions. These spectra reveal the
evolution of energetics across the metal-insulator transition, including the
low temperature appearance of a strong candidate for the singlet-triplet
excitation of a vanadium dimer.


title: A superfluid boundary layer

abstract:
  We model the superfluid flow of liquid helium over the rough surface of a
wire (used to experimentally generate turbulence) profiled by atomic force
microscopy. Numerical simulations of the Gross-Pitaevskii equation reveal that
the sharpest features in the surface induce vortex nucleation both
intrinsically (due to the raised local fluid velocity) and extrinsically
(providing pinning sites to vortex lines aligned with the flow). Vortex
interactions and reconnections contribute to form a dense turbulent layer of
vortices with a non-classical average velocity profile which continually sheds
small vortex rings into the bulk. We characterise this layer for various
imposed flows. As boundary layers conventionally arise from viscous forces,
this result opens up new insight into the nature of superflows.


title:
Regularity of Villadsen algebras and characters on their central
  sequence algebras

abstract:
  We show that if A is a simple Villadsen algebra of either the first type with
seed space a finite dimensional CW complex, or of the second type, then $A$
absorbs the Jiang-Su algebra tensorially if and only if the central sequence
algebra of A does not admit characters. Additionally, in a joint appendix with
Joan Bosa, we show that the Villadsen algebra of the second type with infinite
stable rank fails the Corona Factorization Property, thus providing the first
example of a unital, simple, separable and nuclear $C^\ast$-algebra with a
unique tracial state which fails to have this property.


title:
On Composite Discontinuous Galerkin Method for simulations of electric
  properties of semiconductor devices

abstract:
  In this paper, a variant of discretization of the van Roosbroeck equations in
the equilibrium state with the Composite Discontinuous Galerkin Method for the
rectangular domain is discussed. It is based on Symmetric Interior Penalty
Galerkin (SIPG) method. The proposed method accounts for lower regularity of
the solution on the interfaces of devices' layers. It is shown that the
discrete problem is well-defined and that discrete solution is unique. Error
estimates are derived. Finally, numerical simulations are presented.


title:
Numerical simulation of wave propagation and snow failure from explosive
  loading

abstract:
  Avalanche control by explosion is a widely applied method to minimize the
avalanche risk to infrastructure in snow-covered mountain areas. However, the
mechanisms involved leading from an explosion to the release of an avalanche
are not well understood. Here we test the hypothesis that weak layers fail due
to the stress caused by propagating acoustic waves. The underlying mechanism is
that the stress induced by the acoustic waves exceeds the strength of the snow
layers. We compare field measurements to a numerical simulation of acoustic
wave propagation in a porous material. The simulation consists of an acoustic
domain for the air above the snowpack and a poroelastic domain for the dry
snowpack. The two domains are connected by a wave field decomposition and open
pore boundary conditions. Empirical relations are used to derive a porous model
of the snowpack from density profiles of the field experiment. Biot's equations
are solved in the poroelastic domain to obtain simulated accelerations in the
snowpack and a time dependent stress field. Locations of snow failure were
identified by comparing the principal normal and shear stress fields to snow
strength which is assumed to be a function of snow porosity. One air pressure
measurement above the snowpack was used to calibrate the pressure amplitude of
the source in the simulation. Additional field measurements of air pressure and
acceleration measurements inside the snowpack were compared to individual field
variables of the simulation. The acceleration of the air flowing inside the
pore space of the snowpack was identified to have the highest correlation to
the acceleration measurements in the snowpack.


title:
Positron annihilation signatures associated with the outburst of the
  microquasar V404 Cygni

abstract:
  Microquasars are stellar-mass black holes accreting matter from a companion
star and ejecting plasma jets at almost the speed of light. They are analogues
of quasars that contain supermassive black holes of $10^6$ to $10^{10}$ solar
masses. Accretion in microquasars varies on much shorter timescales than in
quasars and occasionally produces exceptionally bright X-ray flares. How the
flares are produced is unclear, as is the mechanism for launching the
relativistic jets and their composition. An emission line near 511
kiloelectronvolts has long been sought in the emission spectrum of microquasars
as evidence for the expected electron-positron plasma. Transient high-energy
spectral features have been reported in two objects, but their positron
interpretation remains contentious. Here we report observations of $\gamma$-ray
emission from the microquasar V404 Cygni during a recent period of strong
flaring activity. The emission spectrum around 511 kiloelectronvolts shows
clear signatures of variable positron annihilation, which implies a high rate
of positron production. This supports the earlier conjecture that microquasars
may be the main sources of the electron-positron plasma responsible for the
bright diffuse emission of annihilation $\gamma$-rays in the bulge region of
our Galaxy. Additionally, microquasars could be the origin of the observed
megaelectronvolt continuum excess in the inner Galaxy.


title: Ion-acoustic cnoidal waves in a quantum plasma

abstract:
  Nonlinear ion-acoustic cnoidal wave structures are studied in an unmagnetized
quantum plasma. Using the reductive perturbation method, a Korteweg-de Vries
equation is derived for appropriate boundary conditions and nonlinear periodic
wave solutions are obtained. The corresponding analytical solution and
numerical plots of the ion-acoustic cnoidal waves and solitons in the phase
plane are presented using the Sagdeev pseudo-potential approach. The variations
in the nonlinear potential of the ion-acoustic cnoidal waves are studied at
different values of quantum parameter $H_{e}$ which is the ratio of electron
plasmon energy to electron Fermi energy defined for degenerate electrons. It is
found that both compressive and rarefactive ion-acoustic cnoidal wave
structures are formed depending on the value of the quantum parameter. The
dependence of the wavelength and frequency on nonlinear wave amplitude is also
presented.


title: 3-dimensional defect TQFTs and their tricategories

abstract:
  We initiate a systematic study of 3-dimensional `defect' topological quantum
field theories, that we introduce as symmetric monoidal functors on stratified
and decorated bordisms. For every such functor we construct a tricategory with
duals, which is the natural categorification of a pivotal bicategory. This
captures the algebraic essence of defect TQFTs, and it gives precise meaning to
the fusion of line and surface defects as well as their duality operations. As
examples, we discuss how Reshetikhin-Turaev and Turaev-Viro theories embed into
our framework, and how they can be extended to defect TQFTs.


title:
L-Kuramoto-Sivashinsky SPDEs vs. time-fractional SPIDEs: exact
  continuity and gradient moduli, 1/2-derivative criticality, and laws

abstract:
  We establish exact, dimension-dependent, spatio-temporal, uniform and local
moduli of continuity for (1) the fourth order L-Kuramoto-Sivashinsky (L-KS)
SPDEs and for (2) the time-fractional stochastic partial integro-differential
equations (SPIDEs), driven by space-time white noise in one-to-three
dimensional space. Both classes were introduced---with Brownian-time-type
kernel formulations---by Allouba in a series of articles starting in 2006,
where he presented class (2) in its rigorous stochastic integral equations
form. He proved existence, uniqueness, and sharp spatio-temporal H\"older
regularity for the above two classes of equations in $d=1,2,3$. We show that
both classes are $(1/2)^-$ H\"older continuously differentiable in space when
$d=1$, and we give the exact uniform and local moduli of continuity for the
gradient in both cases. This is unprecedented for SPDEs driven by space-time
white noise. Our results on exact moduli show that the half-derivative SPIDE is
a critical case. It signals the onset of rougher modulus regularity in space
than both time-fractional SPIDEs with time-derivatives of order $<1/2$ and L-KS
SPDEs. This is despite the fact that they all have identical spatial H\"older
regularity, as shown earlier by Allouba. Moreover, we show that the temporal
laws governing (1) and (2) are fundamentally different. We relate L-KS SPDEs to
the Houdr\'e-Villa bifractional Brownian motion, yielding a Chung-type law of
the iterated logarithm for these SPDEs. We use the underlying explicit kernels
and spectral/harmonic analysis to prove our results. On one hand, this work
builds on the recent works on delicate sample path properties of Gaussian
random fields. On the other hand, it builds on and complements Allouba's
earlier works on (1) and (2). Similar regularity results hold for Allen-Cahn
nonlinear versions of (1) and (2) on compacts via change of measure.


title:
Ballistic Transport for Limit-Periodic Jacobi Matrices with Applications
  to Quantum Many-Body Problems

abstract:
  We study Jacobi matrices that are uniformly approximated by periodic
operators. We show that if the rate of approximation is sufficiently rapid,
then the associated quantum dynamics are ballistic in a rather strong sense;
namely, the (normalized) Heisenberg evolution of the position operator
converges strongly to a self-adjoint operator that is injective on the space of
absolutely summable sequences. In particular, this means that all transport
exponents corresponding to well-localized initial states are equal to one. Our
result may be applied to a class of quantum many-body problems. Specifically,
we establish a lower bound on the Lieb--Robinson velocity for an isotropic XY
spin chain on the integers with limit-periodic couplings.


title: Seiberg-Witten theory as a Fermi gas

abstract:
  We explore a new connection between Seiberg-Witten theory and quantum
statistical systems by relating the dual partition function of SU(2) Super
Yang-Mills theory in a self-dual Omega-background to the spectral determinant
of an ideal Fermi gas. We show that the spectrum of this gas is encoded in the
zeroes of the Painleve III tau function. In addition we find that the Nekrasov
partition function on this background can be expressed as an O(2) matrix model.
Our construction arises as a four-dimensional limit of a recently proposed
conjecture relating topological strings and spectral theory. In this limit, we
provide a mathematical proof of the conjecture for the local P1xP1 geometry.


title: Permutation polynomials of the form x+c*Tr(x^k)

abstract:
  Let F_{q^n} be the field of order q^n, and let Tr be the trace map from
F_{q^n} to its q-element subfield. We exhibit nine sequences of polynomials of
the form f(x):=x+c*Tr(x^k), with c in F_{q^n}, such that for each polynomial
the function F_{q^n}-->F_{q^n} given by c-->f(c) is a permutation of F_{q^n}.
We also computed all permutation polynomials of this form over finite fields of
size less than 5000, and found that our examples comprise all examples with n>1
except for some simple cases where the polynomial induces a homomorphism of the
additive group of F_{q^n}, along with a few sporadic examples. One intriguing
feature is that our proofs of the different sequences use various different
methods, including a new variant of Dobbertin's method among others.


title:
Time-Dependent Density Functional Theory Beyond Kohn-Sham Slater
  Determinants

abstract:
  When running time-dependent density functional theory (TDDFT) calculations
for real-time simulations of non-equilibrium dynamics, the user has a choice of
initial Kohn-Sham state, and typically a Slater determinant is used. We explore
the impact of this choice on the exchange-correlation potential when the
physical system begins in a 50:50 superposition of the ground and first-excited
state of the system. We investigate the possibility of judiciously choosing a
Kohn-Sham initial state that minimizes errors when adiabatic functionals are
used. We find that if the Kohn-Sham state is chosen to have a configuration
matching the one that dominates the interacting state, this can be achieved for
a finite time duration for some but not all such choices. When the Kohn-Sham
system does not begin in a Slater determinant, we further argue that the
conventional splitting of the exchange-correlation potential into exchange and
correlation parts has limited value, and instead propose a decomposition into a
"single-particle" contribution that we denote $v_{xc}^s$, and a remainder. The
single-particle contribution can be readily computed as an explicit
orbital-functional, reduces to exchange in the Slater determinant case, and
offers an alternative to the adiabatic approximation as a starting point for
TDDFT approximations.


title:
Atmospheric NLTE-Models for the Spectroscopic Analysis of Blue Stars
  with Winds. III. X-ray emission from wind-embedded shocks

abstract:
  X-rays/EUV radiation emitted from wind-embedded shocks in hot, massive stars
can affect the ionization balance in their outer atmospheres, and can be the
mechanism responsible for the production of highly ionized species. To allow
for these processes in the context of spectral analysis, we have implemented
such emission into our unified, NLTE model atmosphere/spectrum synthesis code
FASTWIND.
  The shock structure and corresponding emission is calculated as a function of
user-supplied parameters. We account for a temperature and density
stratification inside the post-shock cooling zones, calculated for radiative
and adiabatic cooling in the inner and outer wind, respectively. The
high-energy absorption of the cool wind is considered by adding important
K-shell opacities, and corresponding Auger ionization rates have been included
into the NLTE network.
  We tested and verified our implementation carefully against corresponding
results from various alternative model atmosphere codes, and studied the
effects from shock emission for important ions from He, C, N, O, Si, and P.
Surprisingly, dielectronic recombination turned out to play an essential role
for the ionization balance of OIV/OV around Teff = 45,000 K. Finally, we
investigated the behavior of the mass absorption coefficient, kappa_nu(r),
important in the context of X-ray line formation in massive star winds.
  In almost all considered cases, direct ionization is of major influence, and
Auger ionization significantly affects only NVI and OVI. The approximation of a
radially constant kappa_nu is justified for r > 1.2 Rstar and lambda < 18 A,
and also for many models at longer wavelengths. To estimate the actual value of
this quantity, however, the HeII opacities need to be calculated from detailed
NLTE modeling, at least for wavelengths longer than 18 to 20 A, and information
on the individual CNO abundances has to be present.


title: Off-shell single-top production at NLO matched to parton showers

abstract:
  We study the hadroproduction of a $Wb$ pair in association with a light jet,
focusing on the dominant $t$-channel contribution and including exactly at the
matrix-element level all non-resonant and off-shell effects induced by the
finite top-quark width. Our simulations are accurate to the next-to-leading
order in QCD, and are matched to the HERWIG6 and PYTHIA8 parton showers through
the MC@NLO method. We present phenomenological results relevant to the 8 TeV
LHC, and carry out a thorough comparison to the case of on-shell $t$-channel
single-top production. We formulate our approach so that it can be applied to
the general case of matrix elements that feature coloured intermediate
resonances and are matched to parton showers.


title: Read networks and k-laminar graphs

abstract:
  In this paper we introduce k-laminar graphs a new class of graphs which
extends the idea of Asteroidal triple free graphs. Indeed a graph is k-laminar
if it admits a diametral path that is k-dominating. This bio-inspired class of
graphs was motivated by a biological application dealing with sequence
similarity networks of reads (called hereafter read networks for short). We
briefly develop the context of the biological application in which this graph
class appeared and then we consider the relationships of this new graph class
among known graph classes and then we study its recognition problem. For the
recognition of k-laminar graphs, we develop polynomial algorithms when k is
fixed. For k=1, our algorithm improves a Deogun and Krastch's algorithm (1999).
We finish by an NP-completeness result when k is unbounded.


title: Cluster C*-algebras and knot polynomials

abstract:
  We construct a representation of the braid groups in a cluster C*-algebra
coming from a triangulation of the Riemann surface S with one or two cusps. It
is shown that the Laurent polynomials attached to the K-theory of such an
algebra are topological invariants of the closure of braids. In particular, the
Jones and HOMFLY polynomials of a knot correspond to the case S being a sphere
with two cusps and a torus with one cusp, respectively.


title: The Domination Game: Proving the 3/5 Conjecture on Isolate-Free Forests

abstract:
  We analyze the domination game, where two players, Dominator and Staller,
construct together a dominating set M in a given graph, by alternately
selecting vertices into M. Each move must increase the size of the dominated
set. The players have opposing goals: Dominator wishes M to be as small as
possible, and Staller has the opposite goal. Kinnersley, West and Zamani
conjectured that when both players play optimally on an isolate-free forest,
there is a guaranteed upper bound for the size of the dominating set that
depends only on the size n of the forest. This bound is 3n/5 when the first
player is Dominator, and (3n+2)/5 when the first player is Staller. The
conjecture was proved for specific families of forests by Kinnersley et al. and
later extended by Bujtas. Here we prove it for all isolate-free forests, by
supplying an algorithm for Dominator that guarantees the desired bound.


title: Network Unfolding Map by Edge Dynamics Modeling

abstract:
  The emergence of collective dynamics in neural networks is a mechanism of the
animal and human brain for information processing. In this paper, we develop a
computational technique using distributed processing elements in a complex
network, which are called particles, to solve semi-supervised learning
problems. Three actions govern the particles' dynamics: generation, walking,
and absorption. Labeled vertices generate new particles that compete against
rival particles for edge domination. Active particles randomly walk in the
network until they are absorbed by either a rival vertex or an edge currently
dominated by rival particles. The result from the model evolution consists of
sets of edges arranged by the label dominance. Each set tends to form a
connected subnetwork to represent a data class. Although the intrinsic dynamics
of the model is a stochastic one, we prove there exists a deterministic version
with largely reduced computational complexity; specifically, with linear
growth. Furthermore, the edge domination process corresponds to an unfolding
map in such way that edges "stretch" and "shrink" according to the vertex-edge
dynamics. Consequently, the unfolding effect summarizes the relevant
relationships between vertices and the uncovered data classes. The proposed
model captures important details of connectivity patterns over the vertex-edge
dynamics evolution, in contrast to previous approaches which focused on only
vertex or only edge dynamics. Computer simulations reveal that the new model
can identify nonlinear features in both real and artificial data, including
boundaries between distinct classes and overlapping structures of data.


title:
Solving systems of polynomial inequalities with algebraic geometry
  methods

abstract:
  The goal of this paper is to provide computational tools able to find a
solution of a system of polynomial inequalities. The set of inequalities is
reformulated as a system of polynomial equations. Three different methods, two
of which taken from the literature, are proposed to compute solutions of such a
system. An example of how such procedures can be used to solve the static
output feedback stabilization problem for a linear parametrically-varying
system is reported.


title:
Invariant domains preserving ALE approximation of hyperbolic systems
  with continuous finite elements

abstract:
  A conservative invariant domain preserving Arbitrary Lagrangian Eulerian
method for solving nonlinear hyperbolic systems is introduced. The method is
explicit in time, works with continuous finite elements and is first-order
accurate in space. One originality of the present work is that the artificial
viscosity is unambiguously defined irrespective of the mesh geometry/anisotropy
and does not depend on any ad hoc parameter. The proposed method is meant to be
a stepping stone for the construction of higher-order methods in space by using
appropriate limitation techniques.


title: Evolving Boolean Regulatory Networks with Variable Gene Expression Times

abstract:
  The time taken for gene expression varies not least because proteins vary in
length considerably. This paper uses an abstract, tuneable Boolean regulatory
network model to explore gene expression time variation. In particular, it is
shown how non-uniform expression times can emerge under certain conditions
through simulated evolution. That is, gene expression time variance appears
beneficial in the shaping of the dynamical behaviour of the regulatory network
without explicit consideration of protein function.


title:
Solar cycle variation of interstellar neutral He, Ne, O density and
  pick-up ions along the Earth's orbit

abstract:
  We simulated the modulation of the interstellar neutral (ISN) He, Ne, and O
density and pick-up ion (PUI) production rate and count rate along the Earth's
orbit over the solar cycle from 2002 to 2013 to verify if solar cycle-related
effects may modify the inferred ecliptic longitude of the ISN inflow direction.
We adopted the classical PUI model with isotropic distribution function and
adiabatic cooling, modified by time- and heliolatitude-dependent ionization
rates and non-zero injection speed of PUIs. We found that the ionization losses
have a noticeable effect on the derivation of the ISN inflow longitude based on
the Gaussian fit to the crescent and cone peak locations. We conclude that the
non-zero radial velocity of the ISN flow and the energy range of the PUI
distribution function that is accumulated are of importance for a precise
reproduction of the PUI count rate along the Earth orbit. However, the temporal
and latitudinal variations of the ionization in the heliosphere, and
particularly their variation on the solar cycle time-scale, may significantly
modify the shape of PUI cone and crescent and also their peak positions from
year to year and thus bias by a few degrees the derived longitude of the ISN
gas inflow direction.


title:
A Dynamic Overlay Supporting Just-In-Time Assembly to Construct
  Customized Hardware Accelerators

abstract:
  Barriers that prevent programmers from using FPGAs include the need to work
within vendor specific CAD tools, knowledge of hardware programming models, and
the requirement to pass each design through synthesis, place and route. In this
work, a dynamic overlay is designed to support Just- In-Time assembly by
composing hardware operators to construct full accelerators. The hardware
operators are pre-synthesized bit- streams and can be downloaded to Partially
Reconfigurable(PR) regions at runtime.


title: Multilogarithmic velocity renormalization in graphene

abstract:
  We reexamine the effect of long-range Coulomb interactions on the
quasiparticle velocity in graphene. Using a nonperturbative functional
renormalization group approach with partial bosonization in the forward
scattering channel and momentum transfer cutoff scheme, we calculate the
quasiparticle velocity, $v (k)$, and the quasiparticle residue, $Z$, with
frequency-dependent polarization. One of our most striking results is that $v (
k ) \propto \ln [ C_k (\alpha) / k ]$ where the momentum- and
interaction-dependent cutoff scale $C_k (\alpha) $ vanishes logarithmically for
$k \rightarrow 0$. Here $k$ is measured with respect to one of the charge
neutrality (Dirac) points and $\alpha=2.2$ is the strength of dimensionless
bare interaction. Moreover, we also demonstrate that the so-obtained
multilogarithmic singularity is reconcilable with the perturbative expansion of
$v (k)$ in powers of the bare interaction.


title: The Orlik-Terao algebra and the cohomology of configuration space

abstract:
  We give a recursive algorithm for computing the Orlik-Terao algebra of the
Coxeter arrangement of type A_{n-1} as a graded representation of S_n, and we
give a conjectural description of this representation in terms of the
cohomology of the configuration space of n points in SU(2) modulo translation.
We also give a version of this conjecture for more general graphical
arrangements.


title:
High quality electron beam acceleration by ionization injection in laser
  wakefields with mid-infrared dual-color lasers

abstract:
  For the laser wakefield acceleration, suppression of beam energy spread while
keeping sufficient charge is one of the key challenges. In order to achieve
this, we propose bichromatic laser ionization injection with combined laser
wavelengths of $2.4\rm \mu m$ and $0.8\rm \mu m$ for wakefield excitation and
for triggering electron injection via field ionization, respectively. A laser
pulse at $2.4\rm \mu m$ wavelength enables one to drive an intense acceleration
structure with relatively low laser power. To further reduce the requirement of
laser power, we also propose to use carbon dioxide as the working gas medium,
where carbon acts as the injection element. Our full three dimensional
particle-in-cell simulations show that electron beams at the GeV energy level
with both low energy spreads (around one percent) and high charges (several
tens of picocoulomb) can be obtained by this scheme with laser parameters
achievable in the near future.


title:
A fixed-parameter algorithm for a routing open shop problem: unit
  processing times, few machines and locations

abstract:
  The open shop problem is to find a minimum makespan schedule to process each
job $J_i$ on each machine $M_q$ for $p_{iq}$ time such that, at any time, each
machine processes at most one job and each job is processed by at most one
machine. We study a problem variant in which the jobs are located in the
vertices of an edge-weighted graph. The weights determine the time needed for
the machines to travel between jobs in different vertices. We show that the
problem with $m$ machines and $n$ unit-time jobs in $g$ vertices is solvable in
$2^{O(gm^2\log gm)}+O(mn\log n)$ time.


title:
Linear and nonlinear ion-acoustic waves in non-relativistic quantum
  plasmas with arbitrary degeneracy

abstract:
  Linear and nonlinear ion-acoustic waves are studied in a fluid model for
non-relativistic, unmagnetized quantum plasma with electrons with an arbitrary
degeneracy degree. The equation of state for electrons follows from a local
Fermi-Dirac distribution function and apply equally well both to fully
degenerate or classical, non-degenerate limits. Ions are assumed to be cold.
Quantum diffraction effects through the Bohm potential are also taken into
account. A general coupling parameter valid for dilute and dense plasmas is
proposed. The linear dispersion relation of the ion-acoustic waves is obtained
and the ion-acoustic speed is discussed for the limiting cases of extremely
dense or dilute systems. In the long wavelength limit the results agree with
quantum kinetic theory. Using the reductive perturbation method, the
appropriate Korteweg-de Vries equation for weakly nonlinear solutions is
obtained and the corresponding soliton propagation is analyzed. It is found
that soliton hump and dip structures are formed depending on the value of the
quantum parameter for the degenerate electrons, which affect the phase
velocities in the dispersive medium.


title:
Infinite many Blow-up solutions for a Schr\"odinger quasilinear elliptic
  problem with a non-square diffusion term

abstract:
  In this paper, we consider existence of positive solutions for the
Schr\"odinger quasilinear elliptic problem $$
  \left\{ \begin{array}{l} \Delta_pu+\Delta_p(|u|^{2\gamma})|u|^{2\gamma-2}u =
a(x)g(u)~ \mbox{on}~ \mathbb{R}^N,\\ u>0\ \mbox{in}~\mathbb{R}^N,\
u(x)\stackrel{\left|x\right|\rightarrow \infty}{\longrightarrow} \infty,
\end{array} \right. $$ where $a(x), ~x\in \mathbb{R}^N$ and $g(s)~s>0$ are a
nonnegative and continuous functions with $g$ being nonincreasing as well,
$\gamma>{1}/{2}$, and $N \geq 1$. By a dual approach we establish sufficient
conditions for existence and multiplicity of solutions for this problem.


title:
Joint scaling limit of a bipolar-oriented triangulation and its dual in
  the peanosphere sense

abstract:
  Kenyon, Miller, Sheffield, and Wilson (2015) showed how to encode a random
bipolar-oriented planar map by means of a random walk with a certain step size
distribution. Using this encoding together with the mating-of-trees
construction of Liouville quantum gravity due to Duplantier, Miller, and
Sheffield (2014), they proved that random bipolar-oriented planar maps converge
in the scaling limit to a $\sqrt{4/3}$-Liouville quantum gravity (LQG) surface
decorated by an independent SLE$_{12}$ in the peanosphere sense, meaning that
the height functions of a particular pair of trees on the maps converge in the
scaling limit to the correlated planar Brownian motion which encodes the
SLE-decorated LQG surface. We improve this convergence result by proving that
the pair of height functions for an infinite-volume random bipolar-oriented
triangulation and the pair of height functions for its dual map converge
jointly in law in the scaling limit to the two planar Brownian motions which
encode the same $\sqrt{4/3}$-LQG surface decorated by both an SLE$_{12}$ curve
and the "dual" SLE$_{12}$ curve which travels in a direction perpendicular (in
the sense of imaginary geometry) to the original curve. This confirms a
conjecture of Kenyon, Miller, Sheffield, and Wilson (2015).


title: Precision Muonium Spectroscopy

abstract:
  The muonium atom is the purely leptonic bound state of a positive muon and an
electron. It has a lifetime of 2.2 $\mu$s. The absence of any known internal
structure provides for precision experiments to test fundamental physics
theories and to determine accurate values of fundamental constants. In
particular groun dstate hyperfine structure transitions can be measured by
microwave spectroscopy to deliver the muon magnetic moment. The frequency of
the 1s-2s transition in the hydrogen-like atom can be determined with laser
spectroscopy to obtain the muon mass. With such measurements fundamental
physical interactions, in particular Quantum Electrodynamics, can also be
tested at highest precision. The results are important input parameters for
experiments on the muon magnetic anomaly. The simplicity of the atom enables
further precise experiments, such as a search for muonium-antimuonium
conversion for testing charged lepton number conservation and searches for
possible antigravity of muons and dark matter.


title: Random Matrices, Boundaries and Branes

abstract:
  This thesis is devoted to the application of random matrix theory to the
study of random surfaces, both discrete and continuous; special emphasis is
placed on surface boundaries and the associated boundary conditions in this
formalism. In particular, using a multi-matrix integral with permutation
symmetry, we are able to calculate the partition function of the Potts model on
a random planar lattice with various boundary conditions imposed. We proceed to
investigate the correspondence between the critical points in the phase diagram
of this model and two-dimensional Liouville theory coupled to conformal field
theories with global $\mathcal{W}$-symmetry. In this context, each boundary
condition can be interpreted as the description of a brane in a family of
bosonic string backgrounds. This investigation suggests that a spectrum of
initially distinct boundary conditions of a given system may become degenerate
when the latter is placed on a random surface of bounded genus, effectively
leaving a smaller set of independent boundary conditions. This curious and
much-debated feature is then further scrutinised by considering the double
scaling limit of a two-matrix integral. For this model, we can show explicitly
how this apparent degeneracy is in fact resolved by accounting for
contributions invisible in string perturbation theory. Altogether, these
developments provide novel descriptions of hitherto unexplored boundary
conditions as well as new insights into the non-perturbative physics of
boundaries and branes.


title:
Clumpy dust clouds and extended atmosphere of the AGB star W Hya
  revealed with VLT/SPHERE-ZIMPOL and VLTI/AMBER

abstract:
  We present visible polarimetric imaging observations of the well-studied AGB
star W Hya taken with VLT/SPHERE-ZIMPOL as well as high spectral resolution
long-baseline interferometric observations with the AMBER instrument of the
Very Large Telescope Interferometer (VLTI). We observed W Hya with
VLT/SPHERE-ZIMPOL at three wavelengths in the continuum (645, 748, and 820 nm),
in the Halpha line at 656.3 nm, and in the TiO band at 717 nm. The VLTI/AMBER
observations were carried out in the wavelength region of the CO first overtone
lines near 2.3 micron with a spectral resolution of 12000. Taking advantage of
the polarimetric imaging capability of SPHERE-ZIMPOL combined with the superb
adaptive optics performance, we have succeeded in spatially resolving three
clumpy dust clouds located at ~50 mas (~2 Rstar) from the central star,
revealing dust formation very close to the star. The AMBER data in the
individual CO lines suggest a molecular outer atmosphere extending to ~3 Rstar.
Furthermore, the SPHERE-ZIMPOL image taken over the Halpha line shows emission
with a radius of up to ~160 mas (~7 Rstar). We found that dust, molecular gas,
and Halpha-emitting hot gas are coexisting within 2--3 Rstar. Our modeling
suggests that the observed polarized intensity maps can reasonably be explained
by large (0.4--0.5 micron) grains of Al2O3 or Mg2SiO4 or MgSiO3 in an optically
thin shell with an inner boundary radius of 1.9--2.0 Rstar. The observed clumpy
structure can be reproduced by a density enhancement by a factor of 4 +/- 1.
The grain size derived from our polarimetric images is consistent with the
prediction of the hydrodynamical models for the mass loss driven by the
scattering due to micron-sized grains. The detection of the clumpy dust clouds
close to the star lends support to the dust formation induced by pulsation and
large convective cells as predicted by the 3-D simulations for AGB stars.


title: Models of torsors and the fundamental group scheme

abstract:
  Given a relative faithfully flat pointed scheme over the spectrum of a
discrete valuation ring $X \to S$ this paper is motivated by the study of the
natural morphism from the fundamental group scheme of the generic fiber $X_\eta
$ to the generic fiber of the fundamental group scheme of $X$. Given a torsor
$T \to X_\eta $ under an affine group scheme $G$ over the generic fiber of $X$,
we address the question to find a model of this torsor over $X$, focusing in
particular on the case where $G$ is finite. We obtain partial answers to this
question, showing for instance that, when $X$ is integral and regular of
relative dimension $1$, such a model exists on some model of $X_{\eta}$
obtained by performing a finite number of N\'eron blow-ups along a closed
subset of the special fiber of $X$. In the first part we show that the relative
fundamental group scheme of $X$ has an interpretation as the Tannaka Galois
group of a tannakian category constructed starting from the universal torsor.


title:
Radio polarization maps of shell-type SNRs I. Effects of a random
  magnetic field component, and thin-shell models

abstract:
  The maps of intensity and polarization of the radio synchrotron emission from
shell-type supernova remnants (SNRs) contain a considerable amount of
information, although of not easy interpretation. With the aim of deriving
constraints on the 3-D spatial distribution of the emissivity, as well as on
the structure of both ordered and random magnetic fields (MFs), we present here
a scheme to model maps of the emission and polarization in SNRs.
  We first generalize the classical treatment of the synchrotron emission to
the case in which the MF is composed by an ordered MF plus an isotropic random
component, with arbitrary relative strengths. In the case of a power-law
particle energy distribution, we derive analytic formulae that formally
resemble those for the classical case. We also treat the case of a shock
compression of a fully random upstream field and we predict that the
polarization fraction in this case should be higher than typically measured in
SNRs. We implement the above treatment into a code, which simulates the
observed polarized emission of an emitting shell, taking into account also the
effect of the internal Faraday rotation.
  Finally, we show simulated maps for different orientations with respect to
the observer, levels of the turbulent MF component, Faraday rotation levels,
distributions of the emissivity (either barrel-shaped or limited to polar
caps), and geometries for the ordered MF component (either tangential to the
shell, or radial). Their analysis allows us to outline properties useful for
the interpretation of radio intensity and polarization maps.


title:
Typical behavior of the harmonic measure in critical Galton-Watson trees
  with infinite variance offspring distribution

abstract:
  We study the typical behavior of the harmonic measure in large critical
Galton-Watson trees whose offspring distribution is in the domain of attraction
of a stable distribution with index $\alpha\in (1,2]$. Let $\mu_n$ denote the
hitting distribution of height $n$ by simple random walk on the critical
Galton-Watson tree conditioned on non-extinction at generation $n$. We extend
the results of arxiv:1502.05584 to prove that, with high probability, the mass
of the harmonic measure $\mu_n$ carried by a random vertex uniformly chosen
from height $n$ is approximately equal to $n^{-\lambda_\alpha}$, where the
constant $\lambda_\alpha >\frac{1}{\alpha-1}$ depends only on the index
$\alpha$. In the analogous continuous model, this constant $\lambda_\alpha$
turns out to be the typical local dimension of the continuous harmonic measure.
Using an explicit formula for $\lambda_\alpha$, we are able to show that
$\lambda_\alpha$ decreases with respect to $\alpha\in(1,2]$, and it goes to
infinity at the same speed as $(\alpha-1)^{-2}$ when $\alpha$ approaches 1.


title:
Constructing Scalar-Photon Three Point Vertex in Massless Quenched
  Scalar QED

abstract:
  Non perturbative studies of Schwinger-Dyson equations (SDEs) require their
infnite, coupled tower to be truncated in order to reduce them to a practically
solvable set. In this connection, a physically acceptable ansatz for the three
point vertex is the most favorite choice. Scalar quantum electrodynamics (sQED)
provides a simple and neat platform to address this problem. The most general
form of the three point scalar-photon vertex can be expressed in terms of only
two independent form factors, a longitudinal and a transverse one. Ball and
Chiu have demonstrated that the longitudinal vertex is fixed by requiring the
Ward-Fradkin-Green-Takahashi identity (WFGTI), while the transverse vertex
remains undetermined. In massless quenched sQED, we construct the transverse
part of the non perturbative scalar-photon vertex. This construction (i)
ensures multiplicative renormalizability (MR) of the scalar propagator in
keeping with the Landau-Khalatnikov-Fradkin transformations (LKFTs), (ii) has
the same transformation properties as the bare vertex under charge conjugation,
parity and time reversal, (iii) has no kinematic singularities and (iv)
reproduces one loop asymptotic result in the weak coupling regime of the
theory.


title: Reducing complexity of autonomous control agents for verifiability

abstract:
  The AgentSpeak type of languages are considered for decision making in
autonomous control systems. To reduce the complexity and increase the
verifiability of decision making, a limited instruction set agent (LISA) is
introduced. The new decision method is structurally simpler than its
predecessors and easily lends itself to both design time and runtime
verification methods. The process of converting a control agent in LISA into a
model in a probabilistic model checker is described. Due to the practical
complexity of design time verification the feasibility of runtime probabilistic
verification is investigated and illustrated in the LISA agent programming
system for verifying symbolic plans of the agent using a probabilistic model
checker.


title: Kulfi: Robust Traffic Engineering Using Semi-Oblivious Routing

abstract:
  Wide-area network traffic engineering enables network operators to reduce
congestion and improve utilization by balancing load across multiple paths.
Current approaches to traffic engineering can be modeled in terms of a routing
component that computes forwarding paths, and a load balancing component that
maps incoming flows onto those paths dynamically, adjusting sending rates to
fit current conditions. Unfortunately, existing systems rely on simple
strategies for one or both of these components, which leads to poor performance
or requires making frequent updates to forwarding paths, significantly
increasing management complexity. This paper explores a different approach
based on semi-oblivious routing, a natural extension of oblivious routing in
which the system computes a diverse set of paths independent of demands, but
also dynamically adapts sending rates as conditions change. Semi-oblivious
routing has a number of important advantages over competing approaches
including low overhead, nearly optimal performance, and built-in protection
against unexpected bursts of traffic and failures. Through in-depth simulations
and a deployment on SDN hardware, we show that these benefits are robust, and
hold across a wide range of topologies, demands, resource budgets, and failure
scenarios.


title: A Theory of Ambulance Chasing

abstract:
  Ambulance chasing is a common socio-scientific phenomenon in particle
physics. I argue that despite the seeming complexity, it is possible to gain
insight into both the qualitative and quantitative features of ambulance
chasing dynamics. Compound-Poisson statistics suffices to accommodate the time
evolution of the cumulative number of papers on a topic, where basic
assumptions that the interest in the topic as well as the number of available
ideas decrease with time appear to drive the time evolution. It follows that if
the interest scales as an inverse power law in time, the cumulative number of
papers on a topic is well described by a di-gamma function, with a distinct
logarithmic behavior at large times. In cases where the interest decreases
exponentially with time, the model predicts that the total number of papers on
the topic will converge to a fixed value as time goes to infinity. I
demonstrate that the two models are able to fit at least 9 specific instances
of ambulance chasing in particle physics using only two free parameters. In
case of the most recent ambulance chasing instance, the ATLAS {\gamma}{\gamma}
excess, fits to the current data predict that the total number of papers on the
topic will not exceed 310 papers by the June 1. 2016, and prior to the natural
cut-off for the validity of the theory.

categories: physics.soc-ph cs.DL hep-ph physics.data-an


title: On fixed point planar algebras

abstract:
  To a weighted graph can be associated a bipartite graph planar algebra P. We
construct and study the symmetric enveloping inclusion of P. We show that this
construction is equivariant with respect to the automorphism group of P. The
automorphism group of the weighted graph acts on P. We consider subgroups G of
the automorphism group of the weighted graph such that the G-fixed point space
P^G is a subfactor planar algebra. As an application we show that if G is
amenable, then P^G is amenable as a subfactor planar algebra. We define the
notions of a cocycle action of a Hecke pair on a tracial von Neumann algebra
and the corresponding cross product. We show that a large class of symmetric
enveloping inclusions of subfactor planar algebras can be described by such a
cross product.


title:
Violation of statistical isotropy and homogeneity in the 21-cm power
  spectrum

abstract:
  Most inflationary models predict primordial perturbations to be statistically
isotropic and homogeneous. Cosmic microwave background (CMB) observations,
however, indicate a possible departure from statistical isotropy in the form of
a dipolar power modulation at large angular scales. Alternative models of
inflation, beyond the simplest single-field slow-roll models, can generate a
small power asymmetry, consistent with these observations. Observations of
clustering of quasars show, however, agreement with statistical isotropy at
much smaller angular scales. Here, we propose to use off-diagonal components of
the angular power spectrum of the 21-cm fluctuations during the dark ages to
test this power asymmetry. We forecast results for the planned SKA radio array,
a future radio array, and the cosmic-variance-limited case as a theoretical
proof of principle. Our results show that the 21-cm line power spectrum will
enable access to information at very small scales and at different redshift
slices, thus improving upon the current CMB constraints by $\sim 2$ orders of
magnitude for a dipolar asymmetry and by $\sim 1-3$ orders of magnitude for a
quadrupolar asymmetry case.


title:
From manuscript catalogues to a handbook of Syriac literature: Modeling
  an infrastructure for Syriaca.org

abstract:
  Despite increasing interest in Syriac studies and growing digital
availability of Syriac texts, there is currently no up-to-date infrastructure
for discovering, identifying, classifying, and referencing works of Syriac
literature. The standard reference work (Baumstark's Geschichte) is over ninety
years old, and the perhaps 20,000 Syriac manuscripts extant worldwide can be
accessed only through disparate catalogues and databases. The present article
proposes a tentative data model for Syriaca.org's New Handbook of Syriac
Literature, an open-access digital publication that will serve as both an
authority file for Syriac works and a guide to accessing their manuscript
representations, editions, and translations. The authors hope that by
publishing a draft data model they can receive feedback and incorporate
suggestions into the next stage of the project.


title: The impact of additional scalar bosons at the LHC

abstract:
  In this study we consider an effective model by introducing two hypothetical
real scalars, $H$ and $\chi$ - a dark matter candidate, where the masses of
these scalars are $2 m_h < m_H < 2 m_t$ and $m_\chi \approx m_h/2$ with $m_h$
and $m_t$ being the Standard Model Higgs boson and top quark masses
respectively. A distortion in the transverse momentum distributions of $h$ in
the intermediate region of the spectrum through the processes $p p \to H \to
h\chi\chi$ could be observed in this model. An additional scalar, $S$, has been
postulated to explain large $H \to h\chi\chi$ branching ratios, assuming $m_h
\lesssim m_S \lesssim m_H-m_h$ and $m_S > 2 m_\chi$. Furthermore, a scenario of
a two Higgs doublet model (2HDM) is introduced and a detailed proposal at the
present energies of the Large Hadron Collider to study the extra CP-even ($h,
H$), CP-odd ($A$) and charged ($H^\pm$) scalars has been pursued. With possible
phenomenological implications, all possible spectra and decay modes for these
scalars are discussed. Based on the mass spectrum of $H, A$ and $H^\pm$, the
production of multi-leptons and $Z$+jets+missing-energy events are predicted. A
specific, Type-II 2HDM model is discussed in detail.


title:
Unrestricted virtual braids, fused links and other quotients of virtual
  braid groups

abstract:
  We consider the group of unrestricted virtual braids, describe its structure
and explore its relations with fused links. Also, we define the groups of flat
virtual braids and virtual Gauss braids and study some of their properties, in
particular their linearity.


title:
On quasidegeneracy of Majorana neutrinos and the observed pattern of
  Leptonic mixing

abstract:
  We relate the observed pattern of leptonic mixing to the quaidegeneracy of
three Majorana neutrinos. We show how lifting the degeneracy may lead to the
measured value of $|U_{13}|$ and to sizeable CP violation of Dirac-type. We
show some of the correlations obtained among physical observables, starting
from some of the most interesting schemes proposed in the literature.