title:
Effects of communication efficiency and exit capacity on fundamental
  diagrams for pedestrian motion in an obscure tunnel - a particle system
  approach

abstract:
  Fundamental diagrams describing the relation between pedestrians speed and
density are key points in understanding pedestrian dynamics. Experimental data
evidence the onset of complex behaviors in which the velocity decreases with
the density and different logistic regimes are identified. This paper addresses
the issue of pedestrians transport and of fundamental diagrams for a scenario
involving the motion of pedestrians escaping from an obscure tunnel. We capture
the effects of the communication efficiency and the exit capacity by means of
two thresholds controlling the rate at which particles (walkers, pedestrians)
move on the lattice. Using a particle system model, we show that in absence of
limitation in communication among pedestrians we reproduce with good accuracy
the standard fundamental diagrams, whose basic behaviors can be interpreted in
terms of the exit capacity limitation. When the effect of a limited
communication ability is considered, then interesting non-intuitive phenomena
occur. Particularly, we shed light on the loss of monotonicity of the typical
speed--density curves, revealing the existence of a pedestrians density
optimizing the escape.
  We study both the discrete particle dynamics as well as the corresponding
hydrodynamic limit (a porous medium equation and a transport (continuity)
equation). We also point out the dependence of the effective transport
coefficients on the two thresholds - the essence of the microstructure
information.


title:
Dynamic Channel Allocation for Interference Mitigation in Relay-assisted
  Wireless Body Networks

abstract:
  We focus on interference mitigation and energy conservation within a single
wireless body area network (WBAN). We adopt two-hop communication scheme
supported by the the IEEE 802.15.6 standard (2012). In this paper, we propose a
dynamic channel allocation scheme, namely DCAIM to mitigate node-level
interference amongst the coexisting regions of a WBAN. At the time, the sensors
are in the radius communication of a relay, they form a relay region (RG)
coordinated by that relay using time division multiple access (TDMA). In the
proposed scheme, each RG creates a table consisting of interfering sensors
which it broadcasts to its neighboring sensors. This broadcast allows each pair
of RGs to create an interference set (IS). Thus, the members of IS are assigned
orthogonal sub-channels whereas other sonsors that do not belong to IS can
transmit using the same time slots. Experimental results show that our proposal
mitigates node-level interference and improves node and WBAN energy savings.
These results are then compared to the results of other schemes. As a result,
our scheme outperforms in all cases. Node-level signal to interference and
noise ratio (SINR) improved by 11dB whilst, the energy consumption decreased
significantly. We further present a probabilistic method and analytically show
the outage probability can be effectively reduced to the minimal.


title:
Periodic Orbits of Gross Pitaevskii in the Disc with Vortices Following
  Point Vortex Flow

abstract:
  We prove the existence of non-constant time periodic vortex solutions to the
Gross-Pitaevskii equations for small but \textit{fixed} $\varepsilon > 0.$ The
vortices of these solutions follow periodic orbits to the point vortex system
of ordinary differential equations \textit{for all time}. The construction uses
two approaches-- constrained minimization techniques adapted from \cite{GS} and
topological minimax techniques adapted from \cite{LinMinMax}, applied to a
formulation of the problem within a rotational ansatz.


title: A QCD sum rule study for a charged bottom-strange scalar meson

abstract:
  Using the QCD sum rule approach we investigate the possible four-quark
structure for the new observed $B_{s}^0\pi^\pm$ narrow structure (D0). We use a
diquak-antidiquark scalar current and work to the order of $m_s$ in full QCD,
without relying on $1/m_Q$ expansion. Our study indicates that although it is
possible to obtain a stable mass in agreement with the state found by the D0
collaboration, a more constraint analysis (simultaneous requirement of the OPE
convergence and the dominance of the pole on the phenomenological side) leads
to a higher mass. We also predict the masses of the bottom scalar tetraquark
resonances with zero and two strange quarks.


title:
Multiscale Equatorial Electrojet Turbulence: Energy Conservation,
  Coupling, and Cascades in a Baseline 2-D Fluid Model

abstract:
  Progress in understanding the coupling between plasma instabilities in the
equatorial electrojet based on a unified fluid model is reported. A deeper
understanding of the linear and nonlinear evolution and the coupling of the
gradient-drift and Farley-Buneman instabilities is achieved by studying the
effect of different combinations of the density-gradient scale-lengths (Ln) and
cross-field (E?B) drifts on the plasma turbulence. Mechanisms and channels of
energy transfer are illucidated for these multiscale instabilities. Energy for
the unified model is examined, including the injected, conservative
redistribution (between fields and scales), and ultimate dissipation. Various
physical mechanisms involved in the energetics are categorized as sources,
sinks, nonlinear transfer, and coupling to show that the system satisfies the
fundamental law of energy Oonservation. The physics of the nonlinear transfer
terms is studied to identify their roles in producing energy cascades { the
transference of energy from the dominant unstable wavenumbers and driving
irregularities of different scale-lengths. The theory of two-step energy
cascading to generate the 3-meter plasma irregularities in the equatorial
electrojet is verified. In addition, the nonlinearity of the system allows the
possibility for a reverse energy cascading, responsible for generating
large-scale plasma structures at the top of the electrojet.


title:
3 neutrino mass experiments fit a strange 3 + 3 model, but will KATRIN
  reveal the model's unique 3-part signature?

abstract:
  Evidence is presented in support of an unconventional $3+3$ model of the
neutrino mass eigenstates with specific $m^2>0$ and $m^2<0$ masses. The two
large $m^2>0$ masses of the model were originally suggested based on a SN 1987A
analysis, and they were further supported by several dark matter fits. The new
evidence for one of the $m^2>0$ mass values comes from an analysis of published
data from the $\emph{three}$ most precise tritium $\beta-$decay experiments.
The KATRIN experiment by virtue of a unique 3-part signature should either
confirm or reject the model in its entirety.


title:
Beyond the French Flag Model: Exploiting Spatial and Gene Regulatory
  Interactions for Positional Information

abstract:
  A crucial step in the early development of multicellular organisms involves
the establishment of spatial patterns of gene expression which later direct
proliferating cells to take on different cell fates. These patterns enable the
cells to infer their global position within a tissue or an organism by reading
out local gene expression levels. The patterning system is thus said to encode
positional information, a concept that was formalized recently in the framework
of information theory. Here we introduce a toy model of patterning in one
spatial dimension, which can be seen as an extension of Wolpert's paradigmatic
"French Flag" model, to patterning by several interacting, spatially coupled
genes subject to intrinsic and extrinsic noise. Our model, a variant of an
Ising spin system, allows us to systematically explore expression patterns that
optimally encode positional information. We find that optimal patterning
systems use positional cues, as in the French Flag model, together with
gene-gene interactions to generate combinatorial codes for position which we
call "Counter" patterns. Counter patterns can also be stabilized against noise
and variations in system size or morphogen dosage by longer-range spatial
interactions of the type invoked in the Turing model. The simple setup proposed
here qualitatively captures many of the experimentally observed properties of
biological patterning systems and allows them to be studied in a single,
theoretically consistent framework.


title:
Kinetic limitation of chemical ordering in Bi$_2$Te$_{3-x}$Se$_x$ layers
  grown by molecular beam epitaxy

abstract:
  We study the chemical ordering in Bi$_2$Te$_{3-x}$Se$_x$ grown by molecular
beam epitaxy on Si substrates. We produce films in the full composition range
from x = 0 to 3, and determine their material properties using energy
dispersive X-ray spectroscopy, X-ray diffraction and Raman spectroscopy. By
fitting the parameters of a kinetic growth model to these results, we obtain a
consistent description of growth at a microscopic level. Our main finding is
that despite the incorporation of Se in the central layer being much more
probable than that of Te, the formation of a fully ordered Te-Bi-Se-Bi-Te layer
is prevented by kinetic of the growth process. Indeed, the Se concentration in
the central layer of Bi$_2$Te$_2$Se$_1$ reaches a maximum of only $\approx$ 75%
even under ideal growth conditions. A second finding of our work is that the
intensity ratio of the 0 0 12 and 0 0 6 X-ray reflections serves as an
experimentally accessible quantitative measure of the degree of ordering in
these films.


title: On Complex Valued Convolutional Neural Networks

abstract:
  Convolutional neural networks (CNNs) are the cutting edge model for
supervised machine learning in computer vision. In recent years CNNs have
outperformed traditional approaches in many computer vision tasks such as
object detection, image classification and face recognition. CNNs are
vulnerable to overfitting, and a lot of research focuses on finding
regularization methods to overcome it. One approach is designing task specific
models based on prior knowledge.
  Several works have shown that properties of natural images can be easily
captured using complex numbers. Motivated by these works, we present a
variation of the CNN model with complex valued input and weights. We construct
the complex model as a generalization of the real model. Lack of order over the
complex field raises several difficulties both in the definition and in the
training of the network. We address these issues and suggest possible
solutions.
  The resulting model is shown to be a restricted form of a real valued CNN
with twice the parameters. It is sensitive to phase structure, and we suggest
it serves as a regularized model for problems where such structure is
important. This suggestion is verified empirically by comparing the performance
of a complex and a real network in the problem of cell detection. The two
networks achieve comparable results, and although the complex model is hard to
train, it is significantly less vulnerable to overfitting. We also demonstrate
that the complex network detects meaningful phase structure in the data.


title: Tunneling method for Hawking radiation in the Nariai case

abstract:
  We revisit the tunneling picture for the Hawking effect in light of the
charged Nariai manifold, because this general relativistic solution, which
displays two horizons, provides the bonus to allow the knowledge of exact
solutions of the field equations. We first perform a revisitation of the
tunneling ansatz in the framework of particle creation in external fields a la
Nikishov, which corroborates the interpretation of the semiclassical emission
rate Gamma as the conditional probability rate for the creation of a couple of
particles from the vacuum. Then, particle creation associated with the Hawking
effect on the Nariai manifold is calculated in two ways. On the one hand, we
apply the Hamilton Jacobi formalism for tunneling, in the case of a charged
scalar field on the given background. On the other hand, the knowledge of the
exact solutions for the Klein Gordon equations on Nariai manifold, and their
analytic properties on the extended manifold, allow us a direct computation of
the flux of particles leaving the horizon, and, as a consequence, we obtain a
further corroboration of the semiclassical tunneling picture from the side of
S-matrix formalism.


title:
Electric Dipole Coupling in Optical Cavities and Its Implications for
  Energy Transfer, Upconversion and Pooling

abstract:
  Resonant energy transfer, energy transfer upconversion, and energy pooling
are considered within optical cavities to elucidate the relationship between
exciton dynamics and donor/acceptor separation distance. This is accomplished
using perturbation theory to derive analytic expressions for the electric
dipole coupling tensors of perfect planar and rectangular channel
reflectors---directly related to a number of important energy transfer
processes. In the near field, the separation dependence along the cavity axis
is not influenced by the cavity and is essentially the same as for
three-dimensional, free space. This is in sharp contrast to the reduced
sensitivity to separation found in idealized low-dimensional settings. The
cavity dynamics only correspond to their reduced dimensional counterparts in
the far field where such excitonic processes are not typically of interest.
There is an intermediate regime, though, where sufficiently small cavities
cause a substantial decrease in separation sensitivity that results in one
component of the dipole-dipole coupling tensor being much larger than those of
free space.


title: One-point localization for branching random walk in Pareto environment

abstract:
  We consider a branching random walk on the lattice, where the branching rates
are given by an i.i.d. Pareto random potential. We show a very strong form of
intermittency, where with high probability most of the mass of the system is
concentrated in a single site with high potential. The analogous one-point
localization is already known for the parabolic Anderson model, which describes
the expected number of particles in the same system. In our case, we rely on
very fine estimates for the behaviour of particles near a good point. This
complements our earlier results that in the rescaled picture most of the mass
is concentrated on a small island.


title:
Design of Pre-Dumping Ring Spin Rotator with a Possibility of Helicity
  Switching for Polarized Positrons at the ILC

abstract:
  The use of polarized beams enhance the possibility of the precision
measurements at the International Linear Collider (ILC). In order to preserve
the degree of polarization during beam transport spin rotators are included in
the current TDR ILC Lattice. In this report some advantages of using a combined
spin rotator/spin flipper are discussed. A few possible lattice designs of spin
flipper developed at DESY in 2012 are presented.


title: Automorphisms of perfect power series rings

abstract:
  Let R be a perfect ring of characteristic p. We show that the group of
continuous R-linear automorphisms of the perfect power series ring over R is
generated by the automorphisms of the ordinary power series ring together with
Frobenius; this answers a question of Jared Weinstein.


title:
On the Generalised Colouring Numbers of Graphs that Exclude a Fixed
  Minor

abstract:
  The generalised colouring numbers $\mathrm{col}_r(G)$ and
$\mathrm{wcol}_r(G)$ were introduced by Kierstead and Yang as a generalisation
of the usual colouring number, and have since then found important theoretical
and algorithmic applications. In this paper, we dramatically improve upon the
known upper bounds for generalised colouring numbers for graphs excluding a
fixed minor, from the exponential bounds of Grohe et al. to a linear bound for
the $r$-colouring number $\mathrm{col}_r$ and a polynomial bound for the weak
$r$-colouring number $\mathrm{wcol}_r$. In particular, we show that if $G$
excludes $K_t$ as a minor, for some fixed $t\ge4$, then
$\mathrm{col}_r(G)\le\binom{t-1}{2}\,(2r+1)$ and
$\mathrm{wcol}_r(G)\le\binom{r+t-2}{t-2}\cdot(t-3)(2r+1)\in\mathcal{O}(r^{\,t-1})$.
In the case of graphs $G$ of bounded genus $g$, we improve the bounds to
$\mathrm{col}_r(G)\le(2g+3)(2r+1)$ (and even $\mathrm{col}_r(G)\le5r+1$ if
$g=0$, i.e. if $G$ is planar) and
$\mathrm{wcol}_r(G)\le\Bigl(2g+\binom{r+2}{2}\Bigr)\,(2r+1)$.


title:
Bayesian estimation of airborne fugitive emissions using a Gaussian
  plume model

abstract:
  A new method is proposed for estimating the rate of fugitive emissions of
particulate matter from multiple time-dependent sources via measurements of
deposition and concentration. We cast this source inversion problem within the
Bayesian framework, and use a forward model based on a Gaussian plume solution.
We present three alternate models for constructing the prior distribution on
the emission rates as functions of time. Next, we present an industrial case
study in which our framework is applied to estimate the rate of fugitive
emissions of lead particulates from a smelter in Trail, British Columbia,
Canada. The Bayesian framework not only provides an approximate solution to the
inverse problem, but also quantifies the uncertainty in the solution. Using
this information we perform an uncertainty propagation study in order to assess
the impact of the estimated sources on the area surrounding the industrial
site.


title:
Lyapunov Indices and the Poincar\'e Mapping in a Study of the Stability
  of the Krebs Cycle

abstract:
  On the basis of a mathematical model, we continue the study of the metabolic
Krebs cycle (or the tricarboxilic acid cycle). For the first time, we consider
its consistency and stability, which depend on the dissipation of a
transmembrane potential formed by the respiratory chain in the plasmatic
membrane of a cell. The phase-parametric characteristic of the dynamics of the
ATP level depending on a given parameter is constructed. The scenario of
formation of multiple autoperiodic and chaotic modes is presented. Poincar\'{e}
sections and mappings are constructed. The stability of modes and the
fractality of the obtained bifurcations are studied. The full spectra of
Lyapunov indices, divergences, KS-entropies, horizons of predictability, and
Lyapunov dimensionalities of strange attractors are calculated. Some
conclusions about the structural-functional connections determining the
dependence of the cell respiration cyclicity on the synchronization of the
functioning of the tricarboxilic acid cycle and the electron transport chain
are presented.


title:
Departure from the constant-period ephemeris for the transiting
  exoplanet WASP-12 b

abstract:
  Most hot Jupiters are expected to spiral in towards their host stars due to
transfering of the angular momentum of the orbital motion to the stellar spin.
Their orbits can also precess due to planet-star interactions. Calculations
show that both effects could be detected for the very-hot exoplanet WASP-12 b
using the method of precise transit timing over a timespan of the order of 10
yr. We acquired new precise light curves for 29 transits of WASP-12 b,
spannning 4 observing seasons from November 2012 to February 2016. New
mid-transit times, together with literature ones, were used to refine the
transit ephemeris and analyse the timing residuals. We find that the transit
times of WASP-12 b do not follow a linear ephemeris with a 5 sigma confidence
level. They may be approximated with a quadratic ephemeris that gives a rate of
change in the orbital period of -2.56 +/- 0.40 x 10^{-2} s/yr. The tidal
quality parameter of the host star was found to be equal to 2.5 x 10^5 that is
comparable to theoretical predictions for Sun-like stars. We also consider a
model, in which the observed timing residuals are interpreted as a result of
the apsidal precession. We find, however, that this model is statistically less
probable than the orbital decay.


title: The relation between the NJL model and QCD with condensed gluons

abstract:
  We try to find the relation between the three-flavor Nambu-Jona-Lasinio model
and QCD based on the hypothesis that the gluon momenta are sharply condensed
around the QCD scale, \mu_g. We find that the effective four- and six-fermion
interactions, G_4 and G_6, should be scaled by G_4 proportional to \mu_g^(-2)
and G_6 proportional to \mu_g^(-5) being consistent with the mass dimension
counting in the obtained effective Lagrangian. We then study the \mu_g
dependence on the phase diagram of the chiral phase transition at finite
temperature and chemical potential and the location of the critical point. We
find that the location of the critical point are sensitively affected by the
value of the introduced gluon energy scale.


title: Eternal Higher Spin Black Holes: a Thermofield Interpretation

abstract:
  We study Lorentzian eternal black holes in the Chern-Simons sector of AdS$_3$
higher spin gravity. We probe such black holes using bulk Wilson lines and
motivate new regularity conditions that must be obeyed by the bulk connections
in order for the geometry to be consistent with an interpretation as a
thermofield state in the dual CFT$_2$. We demonstrate that any higher spin
black hole may be placed in a gauge that satisfies these conditions: this is
the Chern-Simons analogue of the construction of Kruskal coordinates that
permit passage through the black hole horizon. We also argue that the Wilson
line provides a higher-spin notion of causality in higher spin gravity that can
be used to associate a Penrose diagram with the black hole. We present some
applications of the formalism, including a study of the time-dependent
entanglement entropy arising from the higher spin black hole interior and
evidence for an emergent AdS$_2$ region in the extremal limit.


title:
Search for supersymmetry at $\sqrt{s}=13$ TeV in final states with jets
  and two same-sign leptons or three leptons with the ATLAS detector

abstract:
  A search for strongly produced supersymmetric particles is conducted using
signatures involving multiple energetic jets and either two isolated leptons
($e$ or $\mu$) with the same electric charge or at least three isolated
leptons. The search also utilises $b$-tagged jets, missing transverse momentum
and other observables to extend its sensitivity. The analysis uses a data
sample of proton-proton collisions at $\sqrt{s}=13$ TeV recorded with the ATLAS
detector at the Large Hadron Collider in 2015 corresponding to a total
integrated luminosity of 3.2 fb$^{-1}$. No significant excess over the Standard
Model expectation is observed. The results are interpreted in several
simplified supersymmetric models and extend the exclusion limits from previous
searches. In the context of exclusive production and simplified decay modes,
gluino masses are excluded at 95% confidence level up to 1.1-1.3 TeV for light
neutralinos (depending on the decay channel), and bottom squark masses are also
excluded up to 540 GeV. In the former scenarios, neutralino masses are also
excluded up to 550-850 GeV for gluino masses around 1 TeV.


title:
The effect of relative velocity and density perturbations between
  baryons and dark matter on the clustering of galaxies

abstract:
  Pre-recombination acoustic oscillations induce non-adiabatic perturbations
between baryons and dark matter, corresponding to a constant relative-density
$\delta_{bc}$ and decaying relative-velocity perturbation $\vec{v}_{bc}$. Due
to their significant large-scale correlations and prominent baryon acoustic
oscillation (BAO) features, these modes are potentially important for the use
of the BAO as standard ruler. We present a complete treatment of the effects of
the baryon-CDM perturbations on galaxy clustering in the context of a rigorous
perturbative bias expansion. The leading effects are proportional to
$\delta_{bc}$ and $\theta_{bc} = \partial_i v_{bc}^i$. We estimate the
magnitude of these terms through the excursion set approach. The contribution
from $v_{bc}^2$, which has attracted significant attention recently,
contributes at subleading (1-loop) order. The relative-density contribution
$\delta_{bc}$ is expected to be by far the largest contribution. We also point
out contributions to the galaxy velocity bias, the largest of which is simply
$v_{bc}$, leading to a term $\propto \mu^2\theta_{bc}$ in the redshift-space
galaxy power spectrum $P_g^s(k,\mu)$. Complete expressions of the galaxy power
spectrum at 1-loop order are given, which contain several new terms.


title: Pressure Anisotropy in Heavy Ion Collisions from Color Glass Condensate

abstract:
  We generalize calculations of the energy-momentum tensor for classical gluon
fields in the McLerran-Venugopalan model using the small-$\tau$ power series
expansion method. Results to all orders for the energy density and pressures
are given in the leading $Q^2$ approximation and with the inclusion of running
coupling effects. The energy density and transverse pressure decrease
monotonically with time while the longitudinal pressure starts from a negative
value and increases towards zero.


title: Bounded Model Checking of Pointer Programs Revisited

abstract:
  Bounded model checking of pointer programs is a debugging technique for
programs that manipulate dynamically allocated pointer structures on the heap.
It is based on the following four observations. First, error conditions like
dereference of a dangling pointer, are expressible in a~fragment of first-order
logic with two-variables. Second, the fragment is closed under weakest
preconditions wrt. finite paths. Third, data structures like trees, lists etc.
are expressible by inductive predicates defined in a fragment of Datalog.
Finally, the combination of the two fragments of the two-variable logic and
Datalog is decidable.
  In this paper we improve this technique by extending the expressivity of the
underlying logics. In a~sequence of examples we demonstrate that the new logic
is capable of modeling more sophisticated data structures with more complex
dependencies on heaps and more complex analyses.


title:
An asymptotic preserving scheme for the relativistic Vlasov--Maxwell
  equations in the classical limit

abstract:
  We consider the relativistic Vlasov--Maxwell (RVM) equations in the limit
when the light velocity $c$ goes to infinity. In this regime, the RVM system
converges towards the Vlasov--Poisson system and the aim of this paper is to
construct asymptotic preserving numerical schemes that are robust with respect
to this limit. Our approach relies on a time splitting approach for the RVM
system employing an implicit time integrator for Maxwell's equations in order
to damp the higher and higher frequencies present in the numerical solution. A
number of numerical simulations are conducted in order to investigate the
performances of our numerical scheme both in the relativistic as well as in the
classical limit regime. In addition, we derive the dispersion relation of the
Weibel instability for the continuous and the discretized problem.


title:
Vortices in stratified protoplanetary disks : From baroclinic
  instability to vortex layers

abstract:
  Large scale vortices could play a key role in the evolution of protoplanetary
disks, particularly in the dead-zone where no turbulence associated with
magnetic field is expected. Their possible formation by the subcritical
baroclinic instability is a complex issue due to the vertical structure of the
disk and to the elliptical instability.} {In two-dimensional disks the
baroclinic instability is studied as a function of the thermal transfer
efficiency. In three-dimensional disks we explore the importance of radial and
vertical stratification on the processes of vortex formation and
amplification.} {Numerical simulations are performed using a fully compressible
hydrodynamical code based on a second order finite volume method. We assume a
perfect gas law in inviscid disk models in which heat transfer is due to either
relaxation or diffusion.} {In 2D, the baroclinic instability with thermal
relaxation leads to the formation of large-scale vortices, which are unstable
with respect to the elliptic instability. In the presence of heat diffusion,
hollow vortices are formed which evolve into vortical structures with a
turbulent core. In 3D, the disk stratification is found to be unstable in a
finite layer which can include the mid-plane or not. When the unstable layer
contains the mid-plane, the 3D baroclinic instability with thermal relaxation
is found to develop first in the unstable layer as in 2D, producing large-scale
vortices. These vortices are then stretched out in the stable layer, creating
long-lived columnar vortical structures extending through the height of the
disk. They are also found to be the source of internal vortex layers that
develop across the whole disk along baroclinic critical layer surfaces, and
form new vortices in the upper region of the disk.} {In three-dimensional
disks, vortices can survive for a very long time if the production of vorticity
by...


title:
Strong reduction of the coercivity by a surface acoustic wave in an
  out-of-plane magnetized epilayer

abstract:
  Inverse magnetostriction is the effect by which magnetization can be changed
upon application of stress/strain. A strain modulation may be created
electrically by exciting interdigitated transducers to generate surface
acoustic waves (SAWs). Hence SAWs appear as a possible route towards
induction-free undulatory magnetic data manipulation. Here we demonstrate
experimentally on an out-of-plane magnetostrictive layer a reduction of the
coercive field of up to 60$\%$ by a SAW, over millimetric distances. A simple
model shows that this spectacular effect can be partly explained by the
periodic lowering of the strain-dependent domain nucleation energy by the SAW.
This proof of concept was done on (Ga,Mn)(As,P), a magnetic semiconductor in
which the out-of-plane magnetic anisotropy can be made very weak by epitaxial
growth; it should guide material engineering for all-acoustic magnetization
switching.


title:
Evaluation of Deep Learning based Pose Estimation for Sign Language
  Recognition

abstract:
  Human body pose estimation and hand detection are two important tasks for
systems that perform computer vision-based sign language recognition(SLR).
However, both tasks are challenging, especially when the input is color videos,
with no depth information. Many algorithms have been proposed in the literature
for these tasks, and some of the most successful recent algorithms are based on
deep learning. In this paper, we introduce a dataset for human pose estimation
for SLR domain. We evaluate the performance of two deep learning based pose
estimation methods, by performing user-independent experiments on our dataset.
We also perform transfer learning, and we obtain results that demonstrate that
transfer learning can improve pose estimation accuracy. The dataset and results
from these methods can create a useful baseline for future works.


title: A random field formulation of Hooke's law in all elasticity classes

abstract:
  For each of the $8$ isotropy classes of elastic materials, we consider a
homogeneous random field taking values in the fixed point set $\mathsf{V}$ of
the corresponding class, that is isotropic with respect to the natural
orthogonal representation of a group lying between the isotropy group of the
class and its normaliser. We find the general form of the correlation tensors
of orders $1$ and $2$ of such a field, and the field's spectral expansion.


title:
Firebird: Predicting Fire Risk and Prioritizing Fire Inspections in
  Atlanta

abstract:
  The Atlanta Fire Rescue Department (AFRD), like many municipal fire
departments, actively works to reduce fire risk by inspecting commercial
properties for potential hazards and fire code violations. However, AFRD's fire
inspection practices relied on tradition and intuition, with no existing
data-driven process for prioritizing fire inspections or identifying new
properties requiring inspection. In collaboration with AFRD, we developed the
Firebird framework to help municipal fire departments identify and prioritize
commercial property fire inspections, using machine learning, geocoding, and
information visualization. Firebird computes fire risk scores for over 5,000
buildings in the city, with true positive rates of up to 71% in predicting
fires. It has identified 6,096 new potential commercial properties to inspect,
based on AFRD's criteria for inspection. Furthermore, through an interactive
map, Firebird integrates and visualizes fire incidents, property information
and risk scores to help AFRD make informed decisions about fire inspections.
Firebird has already begun to make positive impact at both local and national
levels. It is improving AFRD's inspection processes and Atlanta residents'
safety, and was highlighted by National Fire Protection Association (NFPA) as a
best practice for using data to inform fire inspections.


title: Clocked single-spin source based on a spin-split superconductor

abstract:
  We propose an accurate clocked single-spin source for ac-spintronic
applications. Our device consists of a superconducting island covered by a
ferromagnetic insulator layer through which it is coupled to superconducting
leads. Single-particle transfer relies on the energy gaps and the island's
charging energy, and is enabled by a bias and a time-periodic gate voltage.
Accurate spin transfer is achieved by the ferromagnetic insulator layer which
polarizes the island, provides spin-selective tunneling barriers and improves
the precision by suppressing Andreev reflection. We analyze realistic material
combinations and experimental requirements which allow for a clocked spin
current in the MHz regime.


title:
On the Practicality of Cryptographically Enforcing Dynamic Access
  Control Policies in the Cloud (Extended Version)

abstract:
  The ability to enforce robust and dynamic access controls on cloud-hosted
data while simultaneously ensuring confidentiality with respect to the cloud
itself is a clear goal for many users and organizations. To this end, there has
been much cryptographic research proposing the use of (hierarchical)
identity-based encryption, attribute-based encryption, predicate encryption,
functional encryption, and related technologies to perform robust and private
access control on untrusted cloud providers. However, the vast majority of this
work studies static models in which the access control policies being enforced
do not change over time. This is contrary to the needs of most practical
applications, which leverage dynamic data and/or policies. In this paper, we
show that the cryptographic enforcement of dynamic access controls on untrusted
platforms incurs computational costs that are likely prohibitive in practice.
Specifically, we develop lightweight constructions for enforcing role-based
access controls (i.e., $\mathsf{RBAC}_0$) over cloud-hosted files using
identity-based and traditional public-key cryptography. This is done under a
threat model as close as possible to the one assumed in the cryptographic
literature. We prove the correctness of these constructions, and leverage
real-world $\mathsf{RBAC}$ datasets and recent techniques developed by the
access control community to experimentally analyze, via simulation, their
associated computational costs. This analysis shows that supporting revocation,
file updates, and other state change functionality is likely to incur
prohibitive overheads in even minimally-dynamic, realistic scenarios. We
identify a number of bottlenecks in such systems, and fruitful areas for future
work that will lead to more natural and efficient constructions for the
cryptographic enforcement of dynamic access controls.


title:
Nanoscale artificial intelligence: creating artificial neural networks
  using autocatalytic reactions

abstract:
  A general methodology is proposed to engineer a system of interacting
components (particles) which is able to self-regulate their concentrations in
order to produce any prescribed output in response to a particular input. The
methodology is based on the mathematical equivalence between artificial neurons
in neural networks and species in autocatalytic reactions, and it specifies the
relationship between the artificial neural network's parameters and the rate
coefficients of the reactions between particle species. Such systems are
characterised by a high degree of robustness as they are able to reach the
desired output despite disturbances and perturbations of the concentrations of
the various species.


title: Fairs for e-commerce: the benefits of aggregating buyers and sellers

abstract:
  In recent years, many new and interesting models of successful online
business have been developed. Many of these are based on the competition
between users, such as online auctions, where the product price is not fixed
and tends to rise. Other models, including group-buying, are based on
cooperation between users, characterized by a dynamic price of the product that
tends to go down. There is not yet a business model in which both sellers and
buyers are grouped in order to negotiate on a specific product or service. The
present study investigates a new extension of the group-buying model, called
fair, which allows aggregation of demand and supply for price optimization, in
a cooperative manner. Additionally, our system also aggregates products and
destinations for shipping optimization. We introduced the following new
relevant input parameters in order to implement a double-side aggregation: (a)
price-quantity curves provided by the seller; (b) waiting time, that is, the
longer buyers wait, the greater discount they get; (c) payment time, which
determines if the buyer pays before, during or after receiving the product; (d)
the distance between the place where products are available and the place of
shipment, provided in advance by the buyer or dynamically suggested by the
system. To analyze the proposed model we implemented a system prototype and a
simulator that allow to study effects of changing some input parameters. We
analyzed the dynamic price model in fairs having one single seller and a
combination of selected sellers. The results are very encouraging and motivate
further investigation on this topic.


title:
On diffusion effects of the perturbed sine-Gordon equation with Neumann
  boundary conditions

abstract:
  The Neumann boundary problem for the perturbed sine-Gordon equation
describing the electrodynamics of Josephson junctions has been considered. The
behavior of a viscous term, described by a higher-order derivative with small
diffusion coefficient, is investigated. The Green function related to the
linear third order operator is determined by means of Fourier series, and
properties of rapid convergence are established. Furthermore, some classes of
solutions of the hyperbolic equation have been determined, proving that there
exists at least one solution whose derivatives are bounded. Results prove that
diffusion effects are bounded and tend to zero when the small diffusion
coefficient tends to zero.


title:
Thickness and electric field dependent polarizability and dielectric
  constant in phosphorene

abstract:
  Based on extensive first principle calculations, we explore the thickness
dependent effective di- electric constant and slab polarizability of few layer
black phosphorene. We find that the dielectric constant in ultra-thin
phosphorene is thickness dependent and it can be further tuned by applying an
out of plane electric field. The decreasing dielectric constant with reducing
number of layers of phosphorene, is a direct consequence of the lower
permittivity of the surface layers and the in- creasing surface to volume
ratio. We also show that the slab polarizability depends linearly on the number
of layers, implying a nearly constant polarizability per phosphorus atom. Our
calculation of the thickness and electric field dependent dielectric properties
will be useful for designing and interpreting transport experiments in gated
phosphorene devices, wherever electrostatic effects such as capacitance, charge
screening etc. are important.


title: Electrostatic Force Between Two Colloidal Spheres

abstract:
  In this dissertation we analyzed the double-layer force interaction between
two dielectric charged colloidal spheres of different radii immersed in a
solution of ions in water and in thermal equilibrium. In the limit of low
electrostatic potential the interaction is governed by the Linearized
Poisson-Boltzmann Equation (LPBE). We obtained an analytical solution from the
LPBE for the electrostatic interaction via multipole expansion, considering a
uniform and fixed surface charge density on the spheres. A code in the
Mathematica platform was developed, allowing us to calculate the force between
the spheres as a function of their separation. In order to validate the code,
we compared our numerical results with the analytical ones in the limits of
Linear Superposition Approximation (LSA) (valid for sphere separations much
greater than the Debye length) and Proximity Force Approximation (PFA) (valid
for sphere separations and Debye length much smaller than the radii of the
spheres).


title: On the lamppost model of accreting black holes

abstract:
  We study the lamppost model, in which the X-ray source in accreting
black-hole systems is located on the rotation axis close to the horizon. We
point out a number of inconsistencies in the widely used lamppost model
relxilllp, e.g., the neglect of the redshift of the photons emitted by the
lamppost and directly observed. They appear to invalidate those model fitting
results for which the source distances from the horizon are within several
gravitational radii. Furthermore, if those results were correct, most of the
photons produced in the lamppost would be trapped by the black hole, and the
luminosity generated in the source as measured at infinity would be much larger
than that observed. This appears to be in conflict with the observed smooth
state transitions between the hard and soft states of X-ray binaries. The
required increase of the accretion rate and the associated efficiency reduction
present also a problem for AGNs. Then, those models imply the luminosity
measured in the local frame to be much higher than that produced in the source
and measured at infinity, due to the additional effects of time dilation and
redshift, and the electron temperature to be higher significantly than that
observed. We show that these conditions imply that the fitted sources would be
out of the pair equilibrium. On the other hand, the above issues pose
relatively minor problems for sources at large distances from the black hole,
where relxilllp can still be used.


title:
Personalized and situation-aware multimodal route recommendations: the
  FAVOUR algorithm

abstract:
  Route choice in multimodal networks shows a considerable variation between
different individuals as well as the current situational context.
Personalization of recommendation algorithms are already common in many areas,
e.g., online retail. However, most online routing applications still provide
shortest distance or shortest travel-time routes only, neglecting individual
preferences as well as the current situation. Both aspects are of particular
importance in a multimodal setting as attractivity of some transportation modes
such as biking crucially depends on personal characteristics and exogenous
factors like the weather. This paper introduces the FAVourite rOUte
Recommendation (FAVOUR) approach to provide personalized, situation-aware route
proposals based on three steps: first, at the initialization stage, the user
provides limited information (home location, work place, mobility options,
sociodemographics) used to select one out of a small number of initial
profiles. Second, based on this information, a stated preference survey is
designed in order to sharpen the profile. In this step a mass preference prior
is used to encode the prior knowledge on preferences from the class identified
in step one. And third, subsequently the profile is continuously updated during
usage of the routing services. The last two steps use Bayesian learning
techniques in order to incorporate information from all contributing
individuals. The FAVOUR approach is presented in detail and tested on a small
number of survey participants. The experimental results on this real-world
dataset show that FAVOUR generates better-quality recommendations w.r.t.
alternative learning algorithms from the literature. In particular the
definition of the mass preference prior for initialization of step two is shown
to provide better predictions than a number of alternatives from the
literature.


title:
Star-forming dwarf galaxies in the Virgo cluster: the link between
  molecular gas, atomic gas, and dust

abstract:
  We present $^{12}$CO(1-0) and $^{12}$CO(2-1) observations of a sample of 20
star-forming dwarfs selected from the Herschel Virgo Cluster Survey, with
oxygen abundances ranging from 12 + log(O/H) ~ 8.1 to 8.8. CO emission is
observed in ten galaxies and marginally detected in another one. CO fluxes
correlate with the FIR 250 $\mu$m emission, and the dwarfs follow the same
linear relation that holds for more massive spiral galaxies extended to a wider
dynamical range. We compare different methods to estimate H2 molecular masses,
namely a metallicity-dependent CO-to-H2 conversion factor and one dependent on
H-band luminosity. The molecular-to-stellar mass ratio remains nearly constant
at stellar masses <~ 10$^9$ M$_{\odot}$, contrary to the atomic hydrogen
fraction, M$_{HI}$/M$_*$, which increases inversely with M$_*$. The flattening
of the M$_{H_2}$/M$_*$ ratio at low stellar masses does not seem to be related
to the effects of the cluster environment because it occurs for both
HI-deficient and HI-normal dwarfs. The molecular-to-atomic ratio is more
tightly correlated with stellar surface density than metallicity, confirming
that the interstellar gas pressure plays a key role in determining the balance
between the two gaseous components of the interstellar medium. Virgo dwarfs
follow the same linear trend between molecular gas mass and star formation rate
as more massive spirals, but gas depletion timescales, $\tau_{dep}$, are not
constant and range between 100 Myr and 6 Gyr. The interaction with the Virgo
cluster environment is removing the atomic gas and dust components of the
dwarfs, but the molecular gas appears to be less affected at the current stage
of evolution within the cluster. However, the correlation between HI deficiency
and the molecular gas depletion time suggests that the lack of gas
replenishment from the outer regions of the disc is lowering the star formation
activity.


title:
Pricing and Hedging GMWB in the Heston and in the Black-Scholes with
  Stochastic Interest Rate Models

abstract:
  Valuing Guaranteed Minimum Withdrawal Benefit (GMWB) has attracted
significant attention from both the academic field and real world financial
markets. As remarked by Yang and Dai, the Black and Scholes framework seems to
be inappropriate for such a long maturity products. Also Chen Vetzal and
Forsyth in showed that the price of these products is very sensitive to
interest rate and volatility parameters. We propose here to use a stochastic
volatility model (Heston model) and a Black Scholes model with stochastic
interest rate (Hull White model). For this purpose we present four numerical
methods for pricing GMWB variables annuities: a hybrid tree-finite difference
method and a Hybrid Monte Carlo method, an ADI finite difference scheme, and a
Standard Monte Carlo method. These methods are used to determine the
no-arbitrage fee for the most popular versions of the GMWB contract, and to
calculate the Greeks used in hedging. Both constant withdrawal, optimal
surrender and optimal withdrawal strategies are considered. Numerical results
are presented which demonstrate the sensitivity of the no-arbitrage fee to
economic, contractual and longevity assumptions.


title:
Simulating Turbulence Using the Astrophysical Discontinuous Galerkin
  Code TENET

abstract:
  In astrophysics, the two main methods traditionally in use for solving the
Euler equations of ideal fluid dynamics are smoothed particle hydrodynamics and
finite volume discretization on a stationary mesh. However, the goal to
efficiently make use of future exascale machines with their ever higher degree
of parallel concurrency motivates the search for more efficient and more
accurate techniques for computing hydrodynamics. Discontinuous Galerkin (DG)
methods represent a promising class of methods in this regard, as they can be
straightforwardly extended to arbitrarily high order while requiring only small
stencils. Especially for applications involving comparatively smooth problems,
higher-order approaches promise significant gains in computational speed for
reaching a desired target accuracy. Here, we introduce our new astrophysical DG
code TENET designed for applications in cosmology, and discuss our first
results for 3D simulations of subsonic turbulence. We show that our new DG
implementation provides accurate results for subsonic turbulence, at
considerably reduced computational cost compared with traditional finite volume
methods. In particular, we find that DG needs about 1.8 times fewer degrees of
freedom to achieve the same accuracy and at the same time is more than 1.5
times faster, confirming its substantial promise for astrophysical
applications.


title: How well can we measure supermassive black hole spin?

abstract:
  Being one of only two fundamental properties black holes possess, the spin of
supermassive black holes (SMBHs) is of great interest for understanding
accretion processes and galaxy evolution. However, in these early days of spin
measurements, consistency and reproducibility of spin constraints have been a
challenge. Here we focus on X-ray spectral modelling of active galactic nuclei
(AGN), examining how well we can truly return known reflection parameters such
as spin under standard conditions. We have created and fit over 4000 simulated
Seyfert 1 spectra each with 375$\pm$1k counts. We assess the fits with
reflection fraction of $R$ = 1 as well as reflection-dominated AGN with $R$ =
5. We also examine the consequence of permitting fits to search for retrograde
spin. In general, we discover that most parameters are over-estimated when
spectroscopy is restricted to the 2.5 - 10.0 keV regime and that models are
insensitive to inner emissivity index and ionization. When the bandpass is
extended out to 70keV, parameters are more accurately estimated. Repeating the
process for $R$ = 5 reduces our ability to measure photon index ($\sim$3 to 8
per cent error and overestimated), but increases precision in all other
parameters -- most notably ionization, which becomes better constrained
($\pm$45 erg cm $\rm{s^{-1}}$) for low ionization parameters ($\xi$$<$200 erg
cm $\rm{s^{-1}}$). In all cases, we find the spin parameter is only well
measured for the most rapidly rotating supermassive black holes (i.e. $a$ $>$
0.8 to about $\pm$0.10) and that inner emissivity index is never well
constrained. Allowing our model to search for retrograde spin did not improve
the results.


title:
Flow Configuration Influence On Darcian And Forchheimer Permeabilities
  Determination

abstract:
  Within the framework of fuel cells, porous materials are used for filtration
purpose. Determining physical properties like porosity and permeability are of
utmost importance to predict and to manage filtration efficiency of the
materials. The permeability of materials is often determined experimentally in
laboratory with disc samples (outlet of the flow is achieved through the porous
material) that are not exactly similar to the tubes which are used in realistic
operating conditions (a main flow is found additionally to the one through the
material). Thus, the effect of a second outlet on the Darcian's permeability
characterization bench should be studied. In the present paper, we present a
new test bench to determine experimentally the Darcy's and Forchheimer's
permeabilities for a porous media by taking into account two outlets. Operating
parameters (temperature, pressure and mass flow rate) are measured for three
different configurations: i) secondary outlet (S.O) is 0% open, ii) S.O is 50%
open and iii) S.O is 100% open. Then Darcy's and Forchheimer's permeability for
all these three cases are compared and discussed in details. It has been found
that the secondary outlet opening does not affect the Darcian's permeability
but have substantial influence on the Forchheimer's one through the
modifications of the range of study (lower mass flow rate penetrates the porous
medium).


title:
A comparison of two methods for detecting abrupt changes in the variance
  of climatic time series

abstract:
  Two methods for detecting abrupt shifts in the variance, Integrated
Cumulative Sum of Squares (ICSS) and Sequential Regime Shift Detector (SRSD),
have been compared on both synthetic and observed time series. In Monte Carlo
experiments, SRSD outperformed ICSS in the overwhelming majority of the
modelled scenarios with different sequences of variance regimes. The SRSD
advantage was particularly apparent in the case of outliers in the series. When
tested on climatic time series, in most cases both methods detected the same
change points in the longer series (252-787 monthly values). The only exception
was the Arctic Ocean SST series, when ICSS found one extra change point that
appeared to be spurious. As for the shorter time series (66-136 yearly values),
ICSS failed to detect any change points even when the variance doubled or
tripled from one regime to another. For these time series, SRSD is recommended.
Interestingly, all the climatic time series tested, from the Arctic to the
Tropics, had one thing in common: the last shift detected in each of these
series was toward a high-variance regime. This is consistent with other
findings of increased climate variability in recent decades.


title:
Analytical Solutions of Classical and Fractional KP-Burger Equation and
  Coupled KdV equation

abstract:
  Evaluation of analytical solutions of non-linear partial differential
equations (both classical and fractional) is a rising subject in Applied
Mathematics because its applications in Physical biological and social
sciences. In this paper we have used generalized Tanh method to find the exact
solution of KP-Burger equation and coupled KdV equation. The fractional
Sub-equation method has been used to find the solution of fractional KP-Burger
equation and fractional coupled KdV equations. The exact solution obtained by
fractional sub-equation method reduces to classical solution when order of
fractional derivative tends to one. Finally numerical simulation has done. The
numerical simulation justifies that the solutions of two fractional
differential equations reduces to shock solution for KP-Burger equation and
soliton solution for coupled KdV equations when order of derivative tends to
one.


title:
Dissecting zero modes and bound states on BPS vortices in
  Ginzburg-Landau superconductors

abstract:
  In this paper the zero modes of fluctuation of cylindrically symmetric
self-dual vortices are analyzed and described in full detail. These BPS
topological defects arise at the critical point between Type II and Type I
superconductors, or, equivalently, when the masses of the Higgs particle and
the vector boson in the Abelian Higgs model are equal. In addition, novel bound
states of Higss and vector bosons trapped by the self-dual vortices at their
core are found and investigated.


title: Vacancy-induced low-energy states in undoped graphene

abstract:
  We demonstrate that a nonzero concentration $n_v$ of static, randomly-placed
vacancies in graphene leads to a density $w$ of zero-energy quasiparticle
states at the band-center $\epsilon=0$ within a tight-binding description with
nearest-neighbour hopping $t$ on the honeycomb lattice. We show that $w$
remains generically nonzero in the compensated case (exactly equal number of
vacancies on the two sublattices) even in the presence of hopping disorder, and
depends sensitively on $n_v$ and correlations between vacancy positions. For
low, {\em but not-too-low} $|\epsilon|/t$ in this compensated case, we show
that the density of states (DOS) $\rho(\epsilon)$ exhibits a strong divergence
of the form $\rho_{\rm 1D}(\epsilon) \sim |\epsilon|^{-1}/
[\log(t/|\epsilon|)]^{(y+1)} $, which crosses over to the universal low-energy
asymptotic form expected on symmetry grounds $\rho_{\rm GW}(\epsilon) \sim
|\epsilon|^{-1}e^{-b[\log(t/|\epsilon|)]^{2/3} }$ below a crossover scale
$\epsilon_c \ll t$. $\epsilon_c$ is found to decrease rapidly with decreasing
$n_v$, while $y$ decreases much more slowly.


title:
General continuum approach for dissipative systems of repulsive
  particles

abstract:
  We propose a general coarse-graining method to derive a continuity equation
that describes any dissipative system of repulsive particles interacting
through short-ranged potentials. In our approach, the effect of
particle-particle correlations is incorporated to the overall balance of
energy, and a non-linear diffusion equation is obtained to represent the
overdamped dynamics. In particular, when the repulsive interaction potential is
a short-ranged power-law, our approach reveals a distinctive correspondence
between particle-particle energy and the generalized thermostatistics of
Tsallis for any non-positive value of the entropic index q. Our methodology can
also be applied to microscopic models of superconducting vortices and complex
plasma, where particle-particle correlations are pronounced at low
concentrations. The resulting continuum descriptions provide elucidating and
useful insights on the microdynamical behavior of these physical systems. The
consistency of our approach is demonstrated by comparison with molecular
dynamics simulations.


title:
An accurate measurement of the baryonic Tully-Fisher relation with
  heavily gas-dominated ALFALFA galaxies

abstract:
  We use a sample of 97 galaxies selected from the ALFALFA 21cm survey to make
an accurate measurement of the baryonic Tully-Fisher relation (BTFR). These
galaxies are specifically selected to be heavily gas-dominated (Mgas/M* >~ 2.7)
and to be oriented edge-on. The former property ensures that the error on the
galactic baryonic mass is small, despite the large systematic uncertainty
involved in galactic stellar mass estimates. The latter property means that
rotational velocities can be derived directly from the width of the 21cm
emission line, without any need for inclination corrections. We measure a slope
for the linewidth-based BTFR of alpha = 3.75 +- 0.11, a value that is somewhat
steeper than (but in broad agreement with) previous literature results. The
relation is remarkably tight, with almost all galaxies being located within a
perpendicular distance of +- 0.1 dex from the best fit line. The low
observational error budget for our sample enables us to establish that, despite
its tightness, the measured linewidth-based BTFR has some small (i.e.,
non-zero) intrinsic scatter. We furthermore find a systematic difference in the
BTFR of galaxies with "double-horned" 21cm line profiles and those with
"peaked" profiles. When we restrict our sample of galaxies to objects in the
former category, we measure a slightly steeper slope of alpha = 4.13 +- 0.15.
Overall, the high-accuracy measurement of the BTFR presented in this article is
intended as a reliable observational benchmark against which to test
theoretical expectations. Here we consider a representative set of
semi-analytic models and hydrodynamic simulations in the LCDM context, as well
as MOND. In the near future, interferometric follow-up observations of several
sample members will enable us to further refine the BTFR measurement, and make
sharper comparisons with theoretical models.


title: To Give or Not to Give: Fair Division for Single Minded Valuations

abstract:
  Single minded agents have strict preferences, in which a bundle is acceptable
only if it meets a certain demand. Such preferences arise naturally in
scenarios such as allocating computational resources among users, where the
goal is to fairly serve as many requests as possible. In this paper we study
the fair division problem for such agents, which is harder to handle due to
discontinuity and complementarities of the preferences.
  Our solution concept---the competitive allocation from equal incomes
(CAEI)---is inspired from market equilibria and implements fair outcomes
through a pricing mechanism. We study the existence and computation of CAEI for
multiple divisible goods, cake cutting, and multiple discrete goods. For the
first two scenarios we show that existence of CAEI solutions is guaranteed,
while for the third we give a succinct characterization of instances that admit
this solution; then we give an efficient algorithm to find one in all three
cases. Maximizing social welfare turns out to be NP-hard in general, however we
obtain efficient algorithms for (i) divisible and discrete goods when the
number of different \emph{types} of players is a constant, (ii) cake cutting
with contiguous demands, for which we establish an interesting connection with
interval scheduling, and (iii) cake cutting with a constant number of players
with arbitrary demands.
  Our solution is useful more generally, when the players have a target set of
desired goods, and very small positive values for any bundle not containing
their target set.


title: Warped AdS_3 Black Holes in Higher Derivative Gravity Theories

abstract:
  We consider warped AdS_3 black holes in generic higher derivatives gravity
theories in 2+1 dimensions. The asymptotic symmetry group of the phase space
containing these black holes is the semi-direct product of a centrally extended
Virasoro algebra and an affine u(1) Kac-Moody algebra. Previous works have
shown that in some specific theories, the entropy of these black holes agrees
with a Cardy-like entropy formula derived for warped conformal field theories.
In this paper, we show that this entropy matching continues to hold for the
most general higher derivative theories of gravity. We also discuss the
existence of phase transitions.


title: Pair creation in the early universe

abstract:
  In the very early universe, a generalized Schwinger effect can create pairs
from both electrical and gravitational fields. The expectation value of
fermionic current induced by these newly created pairs has been recently
computed in de Sitter spacetime. I will discuss different limiting cases of
this result and some of its possible physical interpretations.


title:
Symanzik-Becchi-Rouet-Stora lessons on renormalizable models with broken
  symmetry: the case of Lorentz violation

abstract:
  In this paper, we revisit the issue intensively studied in recent years on
the generation of terms by radiative corrections in models with broken Lorentz
symmetry. The algebraic perturbative method of handling the problem of
renormalization of the theories with Lorentz symmetry breaking, is used. We
hope to make clear the Symanzik's aphorism: "{\it Whether you like it or not,
you have to include in the lagrangian all counter terms consistent with
locality and power-counting, unless otherwise constrained by Ward identities.}"


title:
A globally convergent numerical method for a 1-d inverse medium problem
  with experimental data

abstract:
  In this paper, a reconstruction method for the spatially distributed
dielectric constant of a medium from the back scattering wave field in the
frequency domain is considered. Our approach is to propose a globally
convergent algorithm, which does not require any knowledge of a small
neighborhood of the solution of the inverse problem in advance. The
Quasi-Reversibility Method (QRM) is used in the algorithm. The convergence of
the QRM is proved via a Carleman estimate. The method is tested on both
computationally simulated and experimental data.


title: Orbits of non-simple closed curves on a surface

abstract:
  The mapping class group of a surface $\S$ acts on the set of closed geodesics
on $\S$. This action preserves self-intersection number. In this paper, we
count the orbits of curves with at most $K$ self-intersections, for each $K
\geq 1$. (The case when $K=0$ is already known.) We also restrict our count to
those orbits that contain geodesics of length at most $L$, for each $L >0$.
This result complements a recent result of Mirzakhani, which gives the
asymptotic growth of the number of closed geodesics of length at most $L$ in a
single mapping class group orbit. Furthermore, we develop a new, combinatorial
approach to studying geodesics on surfaces, which should be of independent
interest.


title:
Planetary gyre, time-dependent eddies, torsional waves, and equatorial
  jets at the Earth's core surface

abstract:
  We report a calculation of time-dependent quasi-geostrophic core flows for
1940-2010. Inverting recursively for an ensemble of solutions, we evaluate the
main source of uncertainties, namely the model errors arising from interactions
between unresolved core surface motions and magnetic fields. Temporal
correlations of these uncertainties are accounted for. The covariance matrix
for the flow coefficients is also obtained recursively from the dispersion of
an ensemble of solutions. Maps of the flow at the core surface show, upon a
planetary-scale gyre, time-dependent large-scale eddies at mid-latitudes and
vigorous azimuthal jets in the equatorial belt. The stationary part of the flow
predominates on all the spatial scales that we can resolve. We retrieve
torsional waves that explain the length-of-day changes at 4 to 9.5 years
periods. These waves may be triggered by the nonlinear interaction between the
magnetic field and sub-decadal non-zonal motions within the fluid outer core.
Both the zonal and the more energetic non-zonal interannual motions were
particularly intense close to the equator (below 10 degrees latitude) between
1995 and 2010. We revise down the amplitude of the decade fluctuations of the
planetary scale circulation and find that electromagnetic core-mantle coupling
is not the main mechanism for angular momentum exchanges on decadal time scales
if mantle conductance is 3 10 8 S or lower.


title:
Grand-Canonical Adaptive Resolution Centroid Molecular Dynamics:
  Implementation and Application

abstract:
  We have implemented the Centroid Molecular Dynamics scheme (CMD) into the
Grand Canonical-like version of the Adaptive Resolution Simulation Molecular
Dynamics (GC-AdResS) method. We have tested the implementation on two different
systems, liquid parahydrogen at extreme thermodynamic conditions and liquid
water at ambient conditions; the reproduction of structural as well as
dynamical results of reference systems are highly satisfactory. The capability
of performing GC-AdResS CMD simulations allows for the treatment of a system
characterized by some quantum features and open boundaries. This latter
characteristic not only is of computational convenience, allowing for
equivalent results of much larger and computationally more expensive systems,
but also suggests a tool of analysis so far not explored, that is the
unambiguous identification of the essential (quantum) degrees of freedom
required for a given property.


title:
Towards optimized surface $\delta$-profiles of nitrogen-vacancy centers
  activated by helium irradiation in diamond

abstract:
  The negatively-charged nitrogen-vacancy (NV) center in diamond has been shown
recently as an excellent sensor for external spins. Nevertheless, their optimum
engineering in the near-surface region still requires quantitative knowledge in
regard to their activation by vacancy capture during thermal annealing. To this
aim, we report on the depth profiles of near-surface helium-induced NV centers
(and related helium defects) by step-etching with nanometer resolution. This
provides insights into the efficiency of vacancy diffusion and recombination
paths concurrent to the formation of NV centers. It was found that the range of
efficient formation of NV centers is limited only to approximately $10$ to
$15\,$nm (radius) around the initial ion track of irradiating helium atoms.
Using this information we demonstrate the fabrication of nanometric-thin
($\delta$) profiles of NV centers for sensing external spins at the diamond
surface based on a three-step approach, which comprises (i) nitrogen-doped
epitaxial CVD diamond overgrowth, (ii) activation of NV centers by low-energy
helium irradiation and thermal annealing, and (iii) controlled layer thinning
by low-damage plasma etching. Spin coherence times (Hahn echo) ranging up to
$50\,$ $\mu$s are demonstrated at depths of less than $5\,$nm in material with
$1.1\,\%$ of $^{13}$C (depth estimated by spin relaxation (T$_1$)
measurements). At the end, the limits of the helium irradiation technique at
high ion fluences are also experimentally investigated.


title:
Local Behavior of Arithmetical Functions with Applications to
  Automorphic L-Functions

abstract:
  We derive a Voronoi-type series approximation for the local weighted mean of
an arithmetical function that is associated to Dirichlet series satisfying a
functional equation with gamma factors. The series is exploited to study the
oscillation frequency with a method of Heath-Brown and Tsang [7]. A by-product
is another proof for the well-known result of no element in the Selberg class
of degree 0 \textless{} d \textless{} 1. Our major applications include the
sign-change problem of the coefficients of automorphic L-functions for GL m ,
which improves significantly some results of Liu and Wu [14]. The cases of
modular forms of half-integral weight and Siegel eigenforms are also
considered.


title:
The global surface composition of 67P/CG nucleus by Rosetta/VIRTIS. I)
  Prelanding mission phase

abstract:
  From August to November 2014 the Rosetta orbiter has performed an extensive
observation campaign aimed at the characterization of 67P/CG nucleus properties
and to the selection of the Philae landing site. The campaign led to the
production of a global map of the illuminated portion of 67P/CG nucleus. During
this prelanding phase the comet's heliocentric distance decreased from 3.62 to
2.93 AU while Rosetta was orbiting around the nucleus at distances between 100
to 10 km. VIRTIS-M, the Visible and InfraRed Thermal Imaging Spectrometer -
Mapping channel (Coradini et al. 2007) onboard the orbiter, has acquired
0.25-5.1 micron hyperspectral data of the entire illuminated surface, e.g. the
north hemisphere and the equatorial regions, with spatial resolution between
2.5 and 25 m/pixel. I/F spectra have been corrected for thermal emission
removal in the 3.5-5.1 micron range and for surface's photometric response. The
resulting reflectance spectra have been used to compute several Cometary
Spectral Indicators (CSI): single scattering albedo at 0.55 micron, 0.5-0.8
micron and 1.0-2.5 micron spectral slopes, 3.2 micron organic material and 2.0
micron water ice band parameters (center, depth) with the aim to map their
spatial distribution on the surface and to study their temporal variability as
the nucleus moved towards the Sun. Indeed, throughout the investigated period,
the nucleus surface shows a significant increase of the single scattering
albedo along with a decrease of the 0.5-0.8 and 1.0-2.5 micron spectral slopes,
indicating a flattening of the reflectance. We attribute the origin of this
effect to the partial removal of the dust layer caused by the increased
contribution of water sublimation to the gaseous activity as comet crossed the
frost-line.


title: The $750$ GeV Diphoton Excesses in a Realistic D-brane Model

abstract:
  We study the diphoton excesses near $750$ GeV recently reported by the ATLAS
and CMS collaborations within the context of a phenomenologically interesting
intersecting/magnetized D-brane model on a toroidal orientifold. It is shown
that the model contains a SM singlet scalar as well as vector-like quarks and
leptons. In addition, it is shown that the singlet scalar has Yukawa couplings
with vector-like quarks and leptons such that it may be produced in
proton-proton collisions via gluon fusion as well as decay to diphotons through
loops involving the vector-like quarks. Moreover, the required vector-like
quarks and leptons may appear in complete $SU(5)$ multiplets so that gauge
coupling unification may be maintained. Finally, it is shown that the diphoton
signal may be explained within the model.


title: Bayesian Variable Selection for Skewed Heteroscedastic Response

abstract:
  In this article, we propose new Bayesian methods for selecting and estimating
a sparse coefficient vector for skewed heteroscedastic response. Our novel
Bayesian procedures effectively estimate the median and other quantile
functions, accommodate non-local prior for regression effects without
compromising ease of implementation via sampling based tools, and
asymptotically select the true set of predictors even when the number of
covariates increases in the same order of the sample size. We also extend our
method to deal with some observations with very large errors. Via simulation
studies and a re-analysis of a medical cost study with large number of
potential predictors, we illustrate the ease of implementation and other
practical advantages of our approach compared to existing methods for such
studies.


title: New Minimal Hypersurfaces in R(k+1)(2k+1) and S(2k+3)k

abstract:
  We find a class of minimal hypersurfaces H(k) as the zero level set of
Pfaffians, resp. determinants of real 2k+2 dimensional antisymmetric matrices.
While H(1) and H(2) are congruent to a 6-dimensional quadratic cone resp.
Hsiang's cubic su(4) invariant in R15, H(k>2) (special harmonic
so(2k+2)-invariant cones of degree>3) seem to be new.


title: Persistent URIs Must Be Used To Be Persistent

abstract:
  We quantify the extent to which references to papers in scholarly literature
use persistent HTTP URIs that leverage the Digital Object Identifier
infrastructure. We find a significant number of references that do not,
speculate why authors would use brittle URIs when persistent ones are
available, and propose an approach to alleviate the problem.


title:
Hydrodynamic limit of granular gases to pressureless Euler in dimension
  1

abstract:
  We investigate the behavior of granular gases in the limit of small Knudsen
number, that is very frequent collisions. We deal with the strongly inelastic
case, in one dimension of space and velocity. We are able to prove the
convergence toward the pressureless Euler system. The proof relies on
dispersive relations at the kinetic level, which leads to the so-called Oleinik
property at the limit.


title:
Leveraging Synergy of 5G SDWN and Multi-Layer Resource Management for
  Network Optimization

abstract:
  Fifth-generation (5G) cellular wireless networks are envisioned to predispose
service-oriented, flexible, and spectrum/energy-efficient edge-to-core
infrastructure, aiming to offer diverse applications. Convergence of
software-defined networking (SDN), software-defined radio (SDR) compatible with
multiple radio access technologies (RATs), and virtualization on the concept of
5G software-defined wireless networking (5G-SDWN) is a promising approach to
provide such a dynamic network. The principal technique behind the 5G-SDWN
framework is the separation of the control and data planes, from the deep core
entities to edge wireless access points (APs). This separation allows the
abstraction of resources as transmission parameters of each user over the
5G-SDWN. In this user-centric and service-oriented environment, resource
management plays a critical role to achieve efficiency and reliability.
However, it is natural to wonder if 5G-SDWN can be leveraged to enable
converged multi-layer resource management over the portfolio of resources, and
reciprocally, if CML resource management can effectively provide performance
enhancement and reliability for 5G-SDWN. We believe that replying to these
questions and investigating this mutual synergy are not trivial, but
multidimensional and complex for 5G-SDWN, which consists of different
technologies and also inherits legacy generations of wireless networks. In this
paper, we propose a flexible protocol structure based on three mentioned
pillars for 5G-SDWN, which can handle all the required functionalities in a
more crosslayer manner. Based on this, we demonstrate how the general framework
of CML resource management can control the end user quality of experience. For
two scenarios of 5G-SDWN, we investigate the effects of joint user-association
and resource allocation via CML resource management to improve performance in a
virtualized network.


title: Analogue Magnetism Revisited

abstract:
  In this article we revisit the significance of the often debated structural
similarity between the equations of electromagnetism and fluid dynamics.
Although the matching of the two sets of equations has successfully been done
for non-dissipative forms of the equations, little has been done for cases
where the dissipative terms are non-negligible. We consider the consequence of
non-negligible viscosity and diffusivity, and how the fine-tuning of these
parameters could allow fluid dynamics to be used to indirectly study certain
properties of magnetic fields.

categories: physics.flu-dyn astro-ph.CO astro-ph.GA astro-ph.SR physics.plasm-ph


title: Perfect Numbers in the Ring of Eisenstein Integers

abstract:
  One of the many number theoretic topics investigated by the ancient Greeks
was perfect numbers, which are positive integers equal to the sum of their
proper positive integral divisors. Mathematicians from Euclid to Euler
investigated these mysterious numbers. We present results on perfect numbers in
the ring of Eisenstein integers.


title:
Estimation of Discretized Motion of Pedestrians by the Decision-Making
  Model

abstract:
  The contribution gives a micro-structural insight into the pedestrian
decision process during an egress situation. A method how to extract the
decisions of pedestrians from the trajectories recorded during the experiments
is introduced. The underlying Markov decision process is estimated using the
finite mixture approximation. Furthermore, the results of this estimation can
be used as an input to the optimization of a Markov decision process for one
`clever' agent. This agent optimizes his strategy of motion with respect to
different reward functions, minimizing the time spent in the room or minimizing
the amount of inhaled CO.


title:
Disease spread through animal movements: a static and temporal network
  analysis of pig trade in Germany

abstract:
  Background: Animal trade plays an important role for the spread of infectious
diseases in livestock populations. As a case study, we consider pig trade in
Germany, where trade actors (agricultural premises) form a complex network. The
central question is how infectious diseases can potentially spread within the
system of trade contacts. We address this question by analyzing the underlying
network of animal movements.
  Methodology/Findings: The considered pig trade dataset spans several years
and is analyzed with respect to its potential to spread infectious diseases.
Focusing on measurements of network-topological properties, we avoid the usage
of external parameters, since these properties are independent of specific
pathogens. They are on the contrary of great importance for understanding any
general spreading process on this particular network. We analyze the system
using different network models, which include varying amounts of information:
(i) static network, (ii) network as a time series of uncorrelated snapshots,
(iii) temporal network, where causality is explicitly taken into account.
  Findings: Our approach provides a general framework for a
topological-temporal characterization of livestock trade networks. We find that
a static network view captures many relevant aspects of the trade system, and
premises can be classified into two clearly defined risk classes. Moreover, our
results allow for an efficient allocation strategy for intervention measures
using centrality measures. Data on trade volume does barely alter the results
and is therefore of secondary importance. Although a static network description
yields useful results, the temporal resolution of data plays an outstanding
role for an in-depth understanding of spreading processes. This applies in
particular for an accurate calculation of the maximum outbreak size.


title: Two-spinor tetrad and Lie derivatives of Einstein-Cartan-Dirac fields

abstract:
  An integrated approach to Lie derivatives of spinors, spinor connections and
the gravitational field is presented, in the context of a previously proposed,
partly original formulation of a theory of Einstein-Carta-Maxwell-Dirac fields
based on "minimal geometric data": all the needed underlying structure is
geometrically constructed from the unique assumption of a complex vector field
$S\to M$ with 2-dimensional fibers. The Lie derivatives of objects of all
considered types, with respect to a vector field $X:M\to TM$, are well-defined
without making any special assumption about $X$, and fulfill natural mutual
relations.


title: Local Thermal Equilibrium States in Relativistic Quantum Field Theory

abstract:
  It is well-known that thermal equilibrium states in quantum statistical
mechanics and quantum field theory can be described in a mathematically
rigorous manner by means of the so-called Kubo-Martin-Schwinger (KMS)
condition, which is based on certain analyticity and periodicity properties of
correlation functions. On the other hand, the characterization of
non-equilibrium states which only locally have thermal properties still
constitutes a challenge in quantum field theory. We discuss a recent proposal
for characterization of such states by a generalized KMS condition. The
connection of this proposal to a proposal by D. Buchholz, I. Ojima and H.-J.
Roos for characterizing local thermal equilibrium states in quantum field
theory is discussed.


title: 2-Distance Colorings of Integer Distance Graphs

abstract:
  A 2-distance k-coloring of a graph G is a mapping from V (G) to the set of
colors {1,. .. , k} such that every two vertices at distance at most 2 receive
distinct colors. The 2-distance chromatic number $\chi$ 2 (G) of G is then the
mallest k for which G admits a 2-distance k-coloring. For any finite set of
positive integers D = {d 1 ,. .. , d k }, the integer distance graph G = G(D)
is the infinite graph defined by V (G) = Z and uv $\in$ E(G) if and only if |v
-- u| $\in$ D. We study the 2-distance chromatic number of integer distance
graphs for several types of sets D. In each case, we provide exact values or
upper bounds on this parameter and characterize those graphs G(D) with $\chi$ 2
(G(D)) = {\Delta}(G(D)) + 1.


title: Favoured $B_c$ Decay modes to search for a Majorana neutrino

abstract:
  Recently, the LHCb collaboration reported the observation of the decay mode
$B_{c}^{-}\rightarrow\overline{B}_{s}^{0}\pi^{-}$ with the largest exclusive
branching fraction amongst the known decay modes of all the $B$ mesons. Here we
propose a search for a few lepton-number violating decay modes of $B_c$ which
can only be induced by Majorana neutrinos. Distinguishing between Dirac and
Majorana nature of neutrinos is an outstanding problem and hence, all possible
searches for Majorana neutrinos need to be carried out. Since the lepton number
violating modes are expected to be rare, when using meson decay modes for these
searches one expects CKM favoured modes to be the preferred ones;
$B_{c}\rightarrow B_{s}$ is one such transition. With a resonance enhancement
of the Majorana neutrino mediating the
$B_{c}^{-}\rightarrow\overline{B}_{s}^{0}\ell_{1}{-}\ell_{2}^{-}\pi^{+}$ modes
one can hope to observe these rare modes, or, even their non-observation can be
used to obtain constraints on the mixing angles of the heavy Majorana singlet
with the light flavour neutrinos from upper limits of the branching fractions
which are tighter or compatible with results from earlier studies. Also, we
find that the relatively suppressed mode $B_{c}^{-}\rightarrow
J/\psi\ell_{1}^{-}\ell_{2}^{-}\pi^{+}$ can provide even tighter constraints on
$\mid V_{e N}\mid^2$, $\mid V_{\mu N}\mid^2$, $\mid V_{e N} V_{\mu N}\mid$, and
in a larger range of the heavy neutrino mass. Further, exclusion regions for
$\mid V_{e N} V_{\tau N}\mid$, $\mid V_{\mu N} V_{\tau N}\mid$ can also be
obtained for masses larger than those accessible in tau decays. Upper limits on
$\mathscr{B}\left(B_{c}^{-}\rightarrow\pi^{+}\ell_{1}^{-}\ell_{2}^{-}\right)$
can also result in stringent exclusion curves for all the mixing elements,
including that for $\mid V_{\tau N}\mid^2$ in a mass range where it is
unconstrained thus far.


title: Symmetril Moulds, Generic Group Schemes, Resummation of Mzvs

abstract:
  The present article deals with various generating series and group schemes
(not necessarily affine ones) associated with MZVs. Our developments are
motivated by Ecalle's mould calculus approach to the latter. We propose in
particular a Hopf algebra--type encoding of symmetril moulds and introduce a
new resummation process for MZVs.


title:
Andreev spectroscopy of iron-based superconductors: temperature
  dependence of the order parameters and scaling of the $\Delta_{L,S}$ with
  $T_C$

abstract:
  We studied iron-based superconductors of various families with critical
temperatures covering almost all range $T_C = 9 - 53$ K. In natural arrays of
contacts formed in these materials we observed intrinsic multiple Andreev
reflections effect (IMARE). By using IMARE spectroscopy, we detected the
two-gap superconductivity, determined the value of the large and the small
superconducting gaps, and the corresponding BCS-ratios. The temperature
dependencies of the large and the small gaps $\Delta_{L,S}(T)$ are similar for
various families of the Fe-based superconductors and could be well-fitted in
the framework of the two-band model by Moskalenko and Suhl. We concluded on the
extended s-wave symmetry of the $\Delta_L$ order parameter (20-30 % anisotropy
in k-space) and on the absence of nodes for $\Delta_S$. The BCS-ratio
$2\Delta_L/k_BT_C \approx 5.2$ is nearly constant within the whole range of
$T_C$ (this means that coupling rate is unchanged), reflecting the 20 %
reduction of the $T_C^{local}$ in relation to the eigen $T_C^L$, and the large
gap roughly corresponds to the energy of magnetic resonance $2\Delta_L \approx
E_{res}$. This result requires a special theoretical consideration. Our
estimation of the relative coupling constants and eigen parameters of each
condensate (in a hypothetical case of a zero interband interaction)
$2\Delta_L/k_BT_C^L = 4.2 - 4.8$ and $2\Delta_S/k_BT_C^S = 3.5 - 4.5$ leads to
indirect conclusion that namely a strong electron-phonon interaction in each
condensate described in the framework of the Eliashberg theory plays the key
role in the superconductivity of iron-based oxypnictides. With it, the two
condensates interact weakly with each other. The observed scaling of
$\Delta_{L,S}$ with $T_C$, as was discussed above, is caused mainly by changing
of the density of states $N_{L,S}$ in the bands, whereas Ln-O spacers act as
charge reservoirs.


title:
Throughput and Coverage for a Mixed Full and Half Duplex Small Cell
  Network

abstract:
  Recent advances in self-interference cancellation enable radios to transmit
and receive on the same frequency at the same time. Such a full duplex radio is
being considered as a potential candidate for the next generation of wireless
networks due to its ability to increase the spectral efficiency of wireless
systems. In this paper, the performance of full duplex radio in small cellular
systems is analyzed by assuming full duplex capable base stations and half
duplex user equipment. However, using only full duplex base stations increases
interference leading to outage. We therefore propose a mixed multi-cell system,
composed of full duplex and half duplex cells. A stochastic geometry based
model of the proposed mixed system is provided, which allows us to derive the
outage and area spectral efficiency of such a system. The effect of full duplex
cells on the performance of the mixed system is presented under different
network parameter settings. We show that the fraction of cells that have full
duplex base stations can be used as a design parameter by the network operator
to target an optimal tradeoff between area spectral efficiency and outage in a
mixed system.


title:
A family of centered random walks on weight lattices conditioned to stay
  in Weyl chambers

abstract:
  Under a natural asumption on the drift, the law of the simple random walk on
the multidimensional first quadrant conditioned to always stay in the first
octant was obtained by O'Connell in [O]. It coincides with that of the image of
the simple random walk under the multidimensional Pitman transform and can be
expressed in terms of specializations of Schur functions. This result has been
generalized in [LLP1] and [LLP2] for a large class of random walks on weight
lattices defined from representations of Kac-Moody algebras and their
conditionings to always stay in Weyl chambers. In these various works, the
drift of the considered random walk is always assumed in the interior of the
cone. In this paper, we introduce for some zero drift random walks defined from
minuscule representations a relevant notion of conditioning to stay in Weyl
chambers and we compute their laws. Namely, we consider the conditioning for
these walks to stay in these cones until an instant we let tend to infinity. We
also prove that the laws so obtained can be recovered by letting the drift tend
to zero in the transitions matrices obtained in [LLP1]. We also conjecture our
results remain true in the more general case of a drift in the frontier of the
Weyl chamber.


title: Some new categorical invariants

abstract:
  We introduce several notions and give examples.
  We prove that ${\rm Stab}(D^b(K(l)))\cong {\mathbb C}\times \mathcal H$ for
$l\geq 3$, where $K(l)$ is $l$-Kronecker quiver. This is an example of SOD,
where ${\rm Stab}( \langle \mathcal T_1,\mathcal T_2\rangle )\not \cong{\rm
Stab}(\mathcal T_1)\times {\rm Stab}(\mathcal T_2)$.
  This example suggest a new notion of a norm, strictly increasing on
$\{D^b(K(l))\}_{l\geq 2}$. To a triangulated category $\mathcal T$ which has
property of a phase gap we attach a non-negative number $\Vert \mathcal T
\Vert_{\varepsilon}$. Natural assumptions on a SOD imply $ \Vert \langle
\mathcal T_1,\mathcal T_2\rangle \Vert_{\varepsilon}\geq {\rm max}\{ \Vert
\mathcal T_1 \Vert_{\varepsilon}, \Vert\mathcal T_2 \Vert_{\varepsilon}\}$.
Using this we define a topology on the set of equivalence classes of
triangulated categories with a phase gap, where the set of discrete derived
categories is a discrete subset and the rationality of a smooth surface $S$
ensures that $[D^b(point)] \in {\rm Cl}([D^b(S)])$.
  Viewing $D^b(K(l))$ as a non-commutative curve, we observe that it is
reasonable to count non-commutative curves in any category in a small
neighborhood of $D^b(K(l))$. Examples show that this idea (non-commutative
curve-counting) opens directions to new categorical structures and connections
to number theory and classical geometry. We give a definition, which
specializes to the non-commutative curve-counting invariants. In an example
arising on the A side we specialize our definition to non-commutative
Calabi-Yau curve-counting, where the entities we count are a Calabi-Yau
modification of $D^b(K(l))$.
  Finally we speculate that one might consider a holomorphic family of
categories, introduced by Kontsevich, as a non-commutative extension with the
norm playing a role similar to the classical notion of degree of an extension
in Galois theory.


title: Easy Monotonic Policy Iteration

abstract:
  A key problem in reinforcement learning for control with general function
approximators (such as deep neural networks and other nonlinear functions) is
that, for many algorithms employed in practice, updates to the policy or
$Q$-function may fail to improve performance---or worse, actually cause the
policy performance to degrade. Prior work has addressed this for policy
iteration by deriving tight policy improvement bounds; by optimizing the lower
bound on policy improvement, a better policy is guaranteed. However, existing
approaches suffer from bounds that are hard to optimize in practice because
they include sup norm terms which cannot be efficiently estimated or
differentiated. In this work, we derive a better policy improvement bound where
the sup norm of the policy divergence has been replaced with an average
divergence; this leads to an algorithm, Easy Monotonic Policy Iteration, that
generates sequences of policies with guaranteed non-decreasing returns and is
easy to implement in a sample-based framework.


title: Mixed degree number field computations

abstract:
  We present a method for computing complete lists of number fields in cases
where the Galois group, as an abstract group, appears as a Galois group in
smaller degree. We apply this method to find the twenty-five octic fields with
Galois group $\textrm{PSL}_2(7)$ and smallest absolute discriminant. We carry
out a number of related computations, including determining the octic field
with Galois group $2^3{:}\textrm{GL}_3(2)$ of smallest absolute discriminant.


title: Multi Snapshot Sparse Bayesian Learning for DOA Estimation

abstract:
  The directions of arrival (DOA) of plane waves are estimated from
multi-snapshot sensor array data using Sparse Bayesian Learning (SBL). The
prior source amplitudes is assumed independent zero-mean complex Gaussian
distributed with hyperparameters the unknown variances (i.e. the source
powers). For a complex Gaussian likelihood with hyperparameter the unknown
noise variance, the corresponding Gaussian posterior distribution is derived.
For a given number of DOAs, the hyperparameters are automatically selected by
maximizing the evidence and promote sparse DOA estimates. The SBL scheme for
DOA estimation is discussed and evaluated competitively against LASSO
($\ell_1$-regularization), conventional beamforming, and MUSIC


title: Exploring the faint source population at 15.7 GHz

abstract:
  We discuss our current understanding of the nature of the faint,
high-frequency radio sky. The Tenth Cambridge (10C) survey at 15.7 GHz is the
deepest high-frequency radio survey to date, covering 12 square degrees to a
completeness limit of 0.5 mJy, making it the ideal starting point from which to
study this population. In this work we have matched the 10C survey to several
lower-frequency radio catalogues and a wide range of multi-wavelength data
(near- and far-infrared, optical and X-ray). We find a significant increase in
the proportion of flat-spectrum sources at flux densities below 1 mJy - the
median radio spectral index between 15.7 GHz and 610 MHz changes from 0.75 for
flux densities greater than 1.5 mJy to 0.08 for flux densities less than 0.8
mJy. The multi-wavelength analysis shows that the vast majority (> 94 percent)
of the 10C sources are radio galaxies; it is therefore likely that these faint,
flat spectrum sources are a result of the cores of radio galaxies becoming
dominant at high frequencies. We have used new observations to extend this
study to even fainter flux densities, calculating the 15.7-GHz radio source
count down to 0.1 mJy, a factor of five deeper than previous studies. There is
no evidence for a new population of sources, showing that the high-frequency
sky continues to be dominated by radio galaxies down to at least 0.1 mJy.


title: Light-induced optomechanical forces in graphene waveguides

abstract:
  We show that the electromagnetic forces generated by the excitations of a
mode in graphene-based optomechanical systems are highly tunable by varying the
graphene chemical potential, and orders of magnitude stronger than usual
non-graphene-based devices, in both attractive and repulsive regimes. We
analyze coupled waveguides made of two parallel graphene sheets, either
suspended or supported by dielectric slabs, and study the interplay between the
light-induced force and the Casimir-Lifshitz interaction. These findings pave
the way to advanced possibilities of control and fast modulation for
optomechanical devices and sensors at the nano- and micro-scales.


title:
A Multi-dimensional Investigation of the Effects of Publication
  Retraction on Scholarly Impact

abstract:
  Over the past few decades, the rate of publication retractions has increased
dramatically in academia. In this study, we investigate retractions from a
quantitative perspective, aiming to answer two fundamental questions. One, how
do retractions influence the scholarly impact of retracted papers, authors, and
institutions? Two, does this influence propagate to the wider academic
community through scholarly associations? Specifically, we analyzed a set of
retracted articles indexed in Thomson Reuters Web of Science (WoS), and ran
multiple experiments to compare changes in scholarly impact against a control
set of non-retracted articles, authors, and institutions. We further applied
the Granger Causality test to investigate whether different scientific topics
are dynamically affected by retracted papers occurring within those topics. Our
results show two key findings: first, the scholarly impact of retracted papers
and authors significantly decreases after retraction, and the most severe
impact decrease correlates to retractions based on proven purposeful scientific
misconduct; second, this retraction penalty does not seem to spread through the
broader scholarly social graph, but instead has a limited and localized effect.
Our findings may provide useful insights for scholars or science committees to
evaluate the scholarly value of papers, authors, or institutions related to
retractions.


title: More results on weighted independent domination

abstract:
  Weighted independent domination is an NP-hard graph problem, which remains
computationally intractable in many restricted graph classes. In particular,
the problem is NP-hard in the classes of sat-graphs and chordal graphs. We
strengthen these results by showing that the problem is NP-hard in a proper
subclass of the intersection of sat-graphs and chordal graphs. On the other
hand, we identify two new classes of graphs where the problem admits
polynomial-time solutions.