title:
Nature of the spin-glass phase in dense packings of Ising dipoles with
  random anisotropy axes

abstract:
  Using tempered Monte Carlo simulations, we study the the spin-glass phase of
dense packings of Ising dipoles pointing along random axes. We consider systems
of L^3 dipoles (a) placed on the sites of a simple cubic lattice with lattice
constant $d$, (b) placed at the center of randomly closed packed spheres of
diameter d that occupy a 64% of the volume. For both cases we find an
equilibrium spin-glass phase below a temperature T_sg. We compute the
spin-glass overlap parameter q and their associated correlation length xi_L.
From the variation of xi_L with T and L we determine T_sg for both systems. In
the spin-glass phase, we find (a) <q> decreases algebraically with L, and (b)
xi_L/L does not diverge as L increases. At very low temperatures we find
comb-like distributions of q that are sample-dependent. We find that the
fraction of samples with cross-overlap spikes higher than a certain value as
well as the average width of the spikes are size independent quantities. All
these results are consistent with a quasi-long-range order in the spin-glass
phase, as found previously for very diluted dipolar systems.


title:
Towards Asymptotically Optimal One-to-One PDP Algorithms for Capacity 2+
  Vehicles

abstract:
  We consider the one-to-one Pickup and Delivery Problem (PDP) in Euclidean
Space with arbitrary dimension $d$ where $n$ transportation requests are picked
i.i.d. with a separate origin-destination pair for each object to be moved.
First, we consider the problem from the customer perspective where the
objective is to compute a plan for transporting the objects such that the
Euclidean distance traveled by the vehicles when carrying objects is minimized.
We develop a polynomial time asymptotically optimal algorithm for vehicles with
capacity $o(\sqrt[2d]{n})$ for this case. This result also holds imposing LIFO
constraints for loading and unloading objects. Secondly, we extend our
algorithm to the classical single-vehicle PDP where the objective is to
minimize the total distance traveled by the vehicle and present results
indicating that the extended algorithm is asymptotically optimal for a fixed
vehicle capacity if the origins and destinations are picked i.i.d. using the
same distribution.


title: Energy Levels of an Ideal Quantum Ring in AA-Stacked Bilayer Graphene

abstract:
  We theoretically analyze the energy spectrum of a quantum ring in AA-stacked
bilayer graphene with radius $R$ for a zero width subjected to a perpendicular
magnetic field $B$. An analytical approach, using the Dirac equation, is
implemented to obtain the energy spectrum by freezing out the carrier radial
motion. The obtained spectrum exhibits different symmetries and for a fixed
total angular momentum $m$, it has a hyperbolic dependence of the magnetic
field. In particular, the energy spectra are not invariant under the
transformation $B \longrightarrow -B$. The application of a potential, on the
upper and lower layer, allows to open a gap in the energy spectrum and the
application of a non zero magnetic field breaks all symmetries. We also analyze
the basics features of the energy spectrum to show the main similarities and
differences with respect to ideal quantum ring in monolayer, AB-stacked bilayer
graphene and a quantum ring with finite width in AB-stacked bilayer graphene.


title: Near-Infrared Imaging Polarimetry of Inner Region of GG Tau A Disk

abstract:
  By performing non-masked polarization imaging with Subaru/HiCIAO, polarized
scattered light from the inner region of the disk around the GG Tau A system
was successfully detected in the $H$ band with a spatial resolution of
approximately 0.07$\arcsec$, revealing the complicated inner disk structures
around this young binary. This paper reports the observation of an arc-like
structure to the north of GG Tau Ab and part of a circumstellar structure that
is noticeable around GG Tau Aa extending to a distance of approximately 28 AU
from the primary star. The speckle noise around GG Tau Ab constrains its disk
radius to <13 AU. Based on the size of the circumbinary ring and the
circumstellar disk around GG Tau Aa, the semi-major axis of the binary's orbit
is likely to be 62 AU. A comparison of the present observations with previous
ALMA and near-infrared (NIR) H$_2$ emission observations suggests that the
north arc could be part of a large streamer flowing from the circumbinary ring
to sustain the circumstellar disks. According to the previous studies, the
circumstellar disk around GG Tau Aa has enough mass and can sustain itself for
a duration sufficient for planet formation; thus, our study indicates that
planets can form within close (separation $\lesssim$ 100 AU) young binary
systems.


title: Heavy going

abstract:
  Chiral symmetry breaking is imaged in graphene which, through a mechanism
analogous to mass generation in quantum electrodynamics, could provide a means
for making it semiconducting.


title:
M\'ethode de Mahler, transcendance et relations lin\'eaires : aspects
  effectifs

abstract:
  This note deals with some effective results in Mahler's method. In a recent
work, we used a theorem of Philippon to show that given a Mahler function
$f(z)$ in ${\bf k}\{z\}$, where ${\bf k}$ denotes a number field, and an
algebraic number $\alpha$ in the domain of holomorphy of $f$, the number
$f(\alpha)$ is either transcendental or belongs to ${\bf k}(\alpha)$. We
describe here an effective procedure to decide if such a number is
transcendental or not. More generally, given several Mahler functions
$f_1(z),\cdots,f_r(z)$ and an algebraic number $\alpha$ in the domain of
holomorphy of these functions, we show how to effectively determine a basis of
the vector space of $\overline{\mathbb Q}$-linear relations between
$f_1(\alpha),\cdots,f_r(\alpha)$.


title:
Numerical test of polarization sum rules for the triply differential
  bremsstrahlung cross section in electron-nucleus encounters

abstract:
  Inspired by the work of Pratt and coworkers on a sum rule for the
polarization correlations in electron bremsstrahlung when the outgoing electron
is not observed, we derive the corresponding sum rule for the elementary
process of bremsstrahlung. This sum rule is valid for arbitrary electron
wavefunctions provided the electron is emitted in the reaction plane. The
numerical evaluation of this sum rule within the Dirac partial-wave theory for
bare inert spin-zero nuclei and collision energies in the range of 1-10 MeV
reveals violations for high nuclear charge. Such violations serve as a measure
of the inaccuracies in the bremsstrahlung calculations.


title: A nonlinear state-space approach to hysteresis identification

abstract:
  Most studies tackling hysteresis identification in the technical literature
follow white-box approaches, i.e. they rely on the assumption that measured
data obey a specific hysteretic model. Such an assumption may be a hard
requirement to handle in real applications, since hysteresis is a highly
individualistic nonlinear behaviour. The present paper adopts a black-box
approach based on nonlinear state-space models to identify hysteresis dynamics.
This approach is shown to provide a general framework to hysteresis
identification, featuring flexibility and parsimony of representation.
Nonlinear model terms are constructed as a multivariate polynomial in the state
variables, and parameter estimation is performed by minimising weighted
least-squares cost functions. Technical issues, including the selection of the
model order and the polynomial degree, are discussed, and model validation is
achieved in both broadband and sine conditions. The study is carried out
numerically by exploiting synthetic data generated via the Bouc-Wen equations.


title:
Detecting heteroskedasticity in nonparametric regression using weighted
  empirical processes

abstract:
  Heteroskedastic errors can lead to inaccurate statistical conclusions if they
are not properly handled. We introduce a test for heteroskedasticity for the
nonparametric regression model with multiple covariates. It is based on a
suitable residual-based empirical distribution function. The residuals are
constructed using local polynomial smoothing. Our test statistic involves a
detection function that can verify heteroskedasticity by exploiting just the
independence-dependence structure between the detection function and model
errors, i.e. we do not require a specific model of the variance function. The
procedure is asymptotically distribution free: inferences made from it do not
depend on unknown parameters. It is consistent at the parametric (root-n) rate
of convergence. Our results are extended to the case of missing responses and
illustrated with simulations.


title: Benchmark calculation of p-3H and n-3He scattering

abstract:
  p-3H and n-3He scattering in the energy range above the n-3He but below the
d-d thresholds is studied by solving the 4-nucleon problem with a realistic
nucleon-nucleon interaction. Three different methods -- Alt, Grassberger and
Sandhas, Hyperspherical Harmonics, and Faddeev-Yakubovsky -- have been employed
and their results for both elastic and charge-exchange processes are compared.
We observe a good agreement between the three different methods, thus the
obtained results may serve as a benchmark. A comparison with the available
experimental data is also reported and discussed.


title: Symbol Synchronization for Diffusive Molecular Communication Systems

abstract:
  Symbol synchronization refers to the estimation of the start of a symbol
interval and is needed for reliable detection. In this paper, we develop a
symbol synchronization framework for molecular communication (MC) systems where
we consider some practical challenges which have not been addressed in the
literature yet. In particular, we take into account that in MC systems, the
transmitter may not be equipped with an internal clock and may not be able to
emit molecules with a fixed release frequency. Such restrictions hold for
practical nanotransmitters, e.g. modified cells, where the lengths of the
symbol intervals may vary due to the inherent randomness in the availability of
food and energy for molecule generation, the process for molecule production,
and the release process. To address this issue, we propose to employ two types
of molecules, one for synchronization and one for data transmission. We derive
the optimal maximum likelihood (ML) symbol synchronization scheme as a
performance upper bound. Since ML synchronization entails high complexity, we
also propose two low-complexity synchronization schemes, namely a peak
observation-based scheme and a threshold-trigger scheme, which are suitable for
MC systems with limited computational capabilities. Our simulation results
reveal the effectiveness of the proposed synchronization~schemes and suggest
that the end-to-end performance of MC systems significantly depends on the
accuracy of symbol synchronization.


title:
Ergodicity breaking and Localization of the Nicolai supersymmetric
  fermion lattice model

abstract:
  We investigate dynamics of the supersymmetric fermion lattice model defined
by Hermann Nicolai. We provide its local fermionic constants of motion that
exist infinitely many. These generate hidden local supersymmetries that the
Nicolai model possesses in addition to its defining dynamical supersymmetry.
The existence of such local constants directly implies the breaking ergodicity
of the model in the sense of Mazur. At zero temperature, there are infinitely
many degenerated classical ground states. We discuss these MBL-like properties.
First, we show the delocalization scenario proposed by De Roeck-Huveneers can
not naively apply to the Nicolai model at zero temperature despite its
disorder-free translation-invariant quantum interaction. Second, we discuss the
quantum integrability of the Nicolai model based on the proposal by
Caux-Mossel.


title:
Measuring the deviation from the superposition principle in interference
  experiments

abstract:
  The Feynman Path Integral formalism has long been used for calculations of
probability amplitudes. Over the last few years, it has been extensively used
to theoretically demonstrate that the usual application of the superposition
principle in slit based interference experiments is often incorrect. This has
caveat in both optics and quantum mechanics where it is often naively assumed
that the boundary condition represented by slits opened individually is same as
them being opened together. The correction term comes from exotic sub leading
terms in the Path Integral which can be described by what are popularly called
non-classical paths. In this work, we report an experiment where we have a
controllable parameter that can be varied in its contribution such that the
effect due to these non-classical paths can be increased or diminished at will.
Thus, the reality of these non-classical paths is brought forth in a classical
experiment using microwaves, thereby proving that the boundary condition effect
being investigated transcends the classical-quantum divide. We report the first
measurement of a deviation (as big as $6\%$) from the superposition principle
in the microwave domain using antennas as sources and detectors of the
electromagnetic waves. We also show that our results can have potential
applications in astronomy.


title:
The VLT LBG Redshift Survey - VI. Mapping HI in the proximity of
  $z\sim3$ LBGs with X-Shooter

abstract:
  We present an analysis of the spatial distribution of gas and galaxies using
new X-Shooter observations of $z\sim3-4$ quasars. Adding the X-Shooter data to
an existing dataset of high resolution quasar spectroscopy, we use a total
sample of 29 quasars alongside $\sim1700$ Lyman Break Galaxies in the redshift
range $2<z<3.5$. Analysing the Ly$\alpha$ forest auto-correlation function
using the full quasar sample, we find $s_0=0.081\pm0.006h^{-1}$Mpc. We then
investigate the clustering and dynamics of Ly$\alpha$ forest absorbers around
$z\sim3$ LBGs. From the redshift-space cross-correlation, we find
$s_0=0.27\pm0.14h^{-1}$Mpc, with power-law slope $\gamma=1.1\pm0.2$. We make a
first analysis of the dependence of this clustering length on absorber strength
based on cuts in the sightline transmitted flux, finding a clear preference for
stronger absorption features to be more strongly clustered around the galaxy
population than weaker absorption features. Further, we calculate the projected
correlation function, finding $r_0=0.24\pm0.04h^{-1}$Mpc (assuming a fixed
slope $\gamma=1.1$). Taking this as the underlying real-space clustering, we
fit the 2D cross-correlation function with a dynamical model incorporating the
infall parameter and the peculiar velocity, finding $\beta_{\rm F}=1.02\pm0.22$
and $240\pm60$ km s$^{-1}$ respectively. This result shows a significant
detection of gas infall relative to the galaxy population, whilst the measured
velocity dispersion is consistent with the velocity uncertainties on the galaxy
redshifts. We evaluate the Cauchy-Schwarz inequality between the galaxy-galaxy,
absorber-absorber, and galaxy-absorber correlation functions, finding a result
significantly less than unity: $\xi_{\rm ag}^2/(\xi_{\rm gg}\xi_{\rm
aa})=0.25\pm0.14$, implying that galaxies and Ly$\alpha$ absorbers do not
linearly trace the underlying dark matter distribution in the same way.


title:
Grey-box nonlinear state-space modelling for mechanical vibrations
  identification

abstract:
  In the present paper, a flexible and parsimonious model of the vibrations of
nonlinear mechanical systems is introduced in the form of state-space
equations. It is shown that the nonlinear model terms can be formed using a
limited number of output measurements. A two-step identification procedure is
derived for this grey-box model, integrating nonlinear subspace initialisation
and maximum likelihood optimisation. The complete procedure is demonstrated on
the Silverbox benchmark, which is an electrical mimicry of a
single-degree-of-freedom mechanical system with one displacement-dependent
nonlinearity.


title:
Performance evaluation of explicit finite difference algorithms with
  varying amounts of computational and memory intensity

abstract:
  Future architectures designed to deliver exascale performance motivate the
need for novel algorithmic changes in order to fully exploit their
capabilities. In this paper, the performance of several numerical algorithms,
characterised by varying degrees of memory and computational intensity, are
evaluated in the context of finite difference methods for fluid dynamics
problems. It is shown that, by storing some of the evaluated derivatives as
single thread- or process-local variables in memory, or recomputing the
derivatives on-the-fly, a speed-up of ~2 can be obtained compared to
traditional algorithms that store all derivatives in global arrays.

categories: cs.DS cs.DC cs.MS physics.comp-ph physics.flu-dyn


title: Min-max embedded geodesic lines in asymptotically conical surfaces

abstract:
  We employ min-max methods to construct uncountably many, geometrically
distinct, properly embedded geodesic lines in any asymptotically conical
surface of non-negative scalar curvature, a setting where minimization schemes
are doomed to fail. Our construction provides control of the Morse index of the
geodesic lines we produce, which will be always less or equal than one (with
equality under suitable curvature or genericity assumptions), as well as of
their precise asymptotic behaviour. In fact, we can prove that in any such
surface for every couple of opposite half-lines there exists an embedded
geodesic line whose two ends are asymptotic, in a suitable sense, to those
half-lines.


title:
Construction of a universal ordinary differential equation $C^{\infty}$
  of order 3

abstract:
  A universal ordinary differential equation $C^{\infty}$ of order 3 is
constructed here. The equation is universal in the sense that any continuous
function on a real segment can be approximated by a solution of this equation
with an arbitrary accuracy in uniform norm.


title:
Functional-renormalization-group analysis of Dzyaloshinsky-Moriya and
  Heisenberg spin interactions on the kagome lattice

abstract:
  We investigate the effects of Dzyaloshinsky-Moriya (DM) interactions on the
frustrated $J_1$-$J_2$ kagome-Heisenberg model using the pseudo-fermion
functional-renormalization-group (PFFRG) technique. In order to treat the
off-diagonal nature of DM interactions, we develop an extended PFFRG scheme. We
benchmark this approach in parameter regimes that have previously been studied
with other methods and find good agreement of the magnetic phase diagram.
Particularly, finite DM interactions are found to stabilize all types of
non-collinear magnetic orders of the $J_1$-$J_2$ Heisenberg model
($\mathbf{q}=0$, $\sqrt{3}\times\sqrt{3}$, and cuboc orders) and shrink the
extents of magnetically disordered phases. We discuss our results in the light
of the mineral {\it herbertsmithite} which has been experimentally predicted to
host a quantum spin liquid at low temperatures. Our PFFRG data indicates that
this material lies in close proximity to a quantum critical point. In parts of
the experimentally relevant parameter regime for {\it herbertsmithite}, the
spin-correlation profile is found to be in good qualitative agreement with
recent inelastic-neutron-scattering data.


title:
NanoSQUID magnetometry of individual cobalt nanoparticles grown by
  focused electron beam induced deposition

abstract:
  We demonstrate the operation of low-noise nano superconducting quantum
interference devices (SQUIDs) based on the high critical field and high
critical temperature superconductor YBa$_2$Cu$_3$O$_7$ (YBCO) as
ultra-sensitive magnetometers for single magnetic nanoparticles (MNPs). The
nanoSQUIDs exploit the Josephson behavior of YBCO grain boundaries and have
been patterned by focused ion beam milling. This allows to precisely define the
lateral dimensions of the SQUIDs so as to achieve large magnetic coupling
between the nanoloop and individual MNPs. By means of focused electron beam
induced deposition, cobalt MNPs with typical size of several tens of nm have
been grown directly on the surface of the sensors with nanometric spatial
resolution. Remarkably, the nanoSQUIDs are operative over extremely broad
ranges of applied magnetic field (-1 T $< \mu_0 H <$ 1 T) and temperature (0.3
K $< T<$ 80 K). All these features together have allowed us to perform
magnetization measurements under different ambient conditions and to detect the
magnetization reversal of individual Co MNPs with magnetic moments (1 - 30)
$\times 10^6\,\mu_{\rm B}$. Depending on the dimensions and shape of the
particles we have distinguished between two different magnetic states yielding
different reversal mechanisms. The magnetization reversal is thermally
activated over an energy barrier, which has been quantified for the (quasi)
single-domain particles. Our measurements serve to show not only the high
sensitivity achievable with YBCO nanoSQUIDs, but also demonstrate that these
sensors are exceptional magnetometers for the investigation of the properties
of individual nanomagnets.


title: Some new results on integration for multifunction

abstract:
  It has been proven in previous papers that each Henstock-Kurzweil-Pettis
integrable multifunction with weakly compact values can be represented as a sum
of one of its selections and a Pettis integrable multifunction. We prove here
that if the initial multifunction is also Bochner measurable and has absolutely
continuous variational measure of its integral, then it is a sum of a strongly
measurable selection and of a variationally Henstock integrable multifunction
that is also Birkhoff integrable.


title: Steerable Discrete Cosine Transform

abstract:
  In image compression, classical block-based separable transforms tend to be
inefficient when image blocks contain arbitrarily shaped discontinuities. For
this reason, transforms incorporating directional information are an appealing
alternative. In this paper, we propose a new approach to this problem, namely a
discrete cosine transform (DCT) that can be steered in any chosen direction.
Such transform, called steerable DCT (SDCT), allows to rotate in a flexible way
pairs of basis vectors, and enables precise matching of directionality in each
image block, achieving improved coding efficiency. The optimal rotation angles
for SDCT can be represented as solution of a suitable rate-distortion (RD)
problem. We propose iterative methods to search such solution, and we develop a
fully fledged image encoder to practically compare our techniques with other
competing transforms. Analytical and numerical results prove that SDCT
outperforms both DCT and state-of-the-art directional transforms.


title:
Observation of the Bloch-Siegert shift in a driven quantum-to-classical
  transition

abstract:
  We show that the counter-rotating terms of the dispersive qubit-cavity Rabi
model can produce relatively large and nonmonotonic Bloch-Siegert shifts in the
cavity frequency as the system is driven through a quantum-to-classical
transition. Using a weak microwave probe tone, we demonstrate experimentally
this effect by monitoring the resonance frequency of a microwave cavity coupled
to a transmon and driven by a microwave field with varying power. In the weakly
driven regime (quantum phase), the Bloch-Siegert shift appears as a small
constant frequency shift, while for strong drive (classical phase) it presents
an oscillatory behaviour as a function of the number of photons in the cavity.
The experimental results are in agreement with numerical simulations based on
the quasienergy spectrum.


title: On the dimension of Bernoulli convolutions

abstract:
  The Bernoulli convolution with parameter $\lambda\in(0,1)$ is the probability
measure $\mu_\lambda$ that is the law of the random variable
$\sum_{n\ge0}\pm\lambda^n$, where the signs are independent unbiased coin
tosses.
  We prove that each parameter $\lambda\in(1/2,1)$ with $\dim\mu_\lambda<1$ can
be approximated by algebraic parameters $\xi\in(1/2,1)$ within an error of
order $\exp(-deg(\xi)^{A})$ for any number $A$, such that $\dim\mu_\xi<1$. As a
corollary, we conclude that $\dim\mu_\lambda=1$ for each of $\lambda=\ln 2,
e^{-1/2}, \pi/4$. These are the first explicit examples of such transcendental
parameters. Moreover, we show that Lehmer's conjecture implies the existence of
a constant $a<1$ such that $\dim\mu_\lambda=1$ for all $\lambda\in(a,1)$.


title: Optimal Design of Helical Springs of Power Law Materials

abstract:
  In this paper the geometric dimensions of a compressive helical spring made
of power law materials are optimized to reduce the amount of material. The
mechanical constraints are derived to form the geometric programming problem.
Both the prime and the dual problem are examined and solved semi-analytically
for a range of spring index. A numerical example is provided to validate the
solutions.


title: Fuzzy Bayesian Learning

abstract:
  In this paper we propose a novel approach for learning from data using rule
based fuzzy inference systems where the model parameters are estimated using
Bayesian inference and Markov Chain Monte Carlo (MCMC) techniques. We show the
applicability of the method for regression and classification tasks using
synthetic data-sets and also a real world example in the financial services
industry. Then we demonstrate how the method can be extended for knowledge
extraction to select the individual rules in a Bayesian way which best explains
the given data. Finally we discuss the advantages and pitfalls of using this
method over state-of-the-art techniques and highlight the specific class of
problems where this would be useful.


title:
Towards automatic pulmonary nodule management in lung cancer screening
  with deep learning

abstract:
  The introduction of lung cancer screening programs will produce an
unprecedented amount of chest CT scans in the near future, which radiologists
will have to read in order to decide on a patient follow-up strategy. According
to the current guidelines, the workup of screen-detected nodules strongly
relies on nodule size and nodule type. In this paper, we present a deep
learning system based on multi-stream multi-scale convolutional networks, which
automatically classifies all nodule types relevant for nodule workup. The
system processes raw CT data containing a nodule without the need for any
additional information such as nodule segmentation or nodule size and learns a
representation of 3D data by analyzing an arbitrary number of 2D views of a
given nodule. The deep learning system was trained with data from the Italian
MILD screening trial and validated on an independent set of data from the
Danish DLCST screening trial. We analyze the advantage of processing nodules at
multiple scales with a multi-stream convolutional network architecture, and we
show that the proposed deep learning system achieves performance at classifying
nodule type that surpasses the one of classical machine learning approaches and
is within the inter-observer variability among four experienced human
observers.


title: Towards a continuous modeling of natural language domains

abstract:
  Humans continuously adapt their style and language to a variety of domains.
However, a reliable definition of `domain' has eluded researchers thus far.
Additionally, the notion of discrete domains stands in contrast to the
multiplicity of heterogeneous domains that humans navigate, many of which
overlap. In order to better understand the change and variation of human
language, we draw on research in domain adaptation and extend the notion of
discrete domains to the continuous spectrum. We propose representation
learning-based models that can adapt to continuous domains and detail how these
can be used to investigate variation in language. To this end, we propose to
use dialogue modeling as a test bed due to its proximity to language modeling
and its social component.


title:
Multidimensional Hall magnetohydrodynamics with isotropic or anisotropic
  thermal pressure: numerical scheme and its validation using solitary waves

abstract:
  We present a numerical solver for plasma dynamics simulations in Hall
magnetohydrodynamic (HMHD) approximation in one, two and three dimensions. We
consider both isotropic and anisotropic thermal pressure cases, where a general
gyrotropic approximation is used. Both explicit energy conservation equation
and general polytropic state equations are considered. The numerical scheme
incorporates second-order Runge-Kutta advancing in time and Kurganov-Tadmor
scheme with van Leer flux limiter for the approximation of fluxes. A
flux-interpolated constrained-transport approach is used to preserve solenoidal
magnetic field in the simulations. The implemented code is validated using
several test problems previously described in the literature. Additionally, we
propose a new validation method for HMHD codes based on solitary waves that
provides a possibility of quantitative rigorous testing in nonlinear (large
amplitude) regime as an extension to standard tests using small-amplitude
whistler waves. Quantitative tests of accuracy and performance of the
implemented code show the fidelity of the proposed approach.


title:
How Users Explore Ontologies on the Web: A Study of NCBO's BioPortal
  Usage Logs

abstract:
  Ontologies in the biomedical domain are numerous, highly specialized and very
expensive to develop. Thus, a crucial prerequisite for ontology adoption and
reuse is effective support for exploring and finding existing ontologies.
Towards that goal, the National Center for Biomedical Ontology (NCBO) has
developed BioPortal---an online repository designed to support users in
exploring and finding more than 500 existing biomedical ontologies. In 2016,
BioPortal represents one of the largest portals for exploration of semantic
biomedical vocabularies and terminologies, which is used by many researchers
and practitioners. While usage of this portal is high, we know very little
about how exactly users search and explore ontologies and what kind of usage
patterns or user groups exist in the first place. Deeper insights into user
behavior on such portals can provide valuable information to devise strategies
for a better support of users in exploring and finding existing ontologies, and
thereby enable better ontology reuse. To that end, we study and group users
according to their browsing behavior on BioPortal using data mining techniques.
Additionally, we use the obtained groups to characterize and compare
exploration strategies across ontologies. In particular, we were able to
identify seven distinct browsing-behavior types, which all make use of
different functionality provided by BioPortal. For example, Search Explorers
make extensive use of the search functionality while Ontology Tree Explorers
mainly rely on the class hierarchy to explore ontologies. Further, we show that
specific characteristics of ontologies influence the way users explore and
interact with the website. Our results may guide the development of more
user-oriented systems for ontology exploration on the Web.


title:
On the Expressive Power of User-Defined Effects: Effect Handlers,
  Monadic Reflection, Delimited Control

abstract:
  We compare the expressive power of three programming abstractions for
user-defined computational effects: Bauer and Pretnar's effect handlers,
Filinski's monadic reflection, and delimited control without
answer-type-modification. This comparison allows a precise discussion about the
relative expressiveness of each programming abstraction. It also demonstrates
the sensitivity of the relative expressiveness of user-defined effects to
seemingly orthogonal language features. We present three calculi, one per
abstraction, extending Levy's call-by-push-value. For each calculus, we present
syntax, operational semantics, a natural type-and-effect system, and, for
effect handlers and monadic reflection, a set-theoretic denotational semantics.
We establish their basic meta-theoretic properties: safety, termination, and,
where applicable, soundness and adequacy. Using Felleisen's notion of a macro
translation, we show that these abstractions can macro-express each other, and
show which translations preserve typeability. We use the adequate finitary
set-theoretic denotational semantics for the monadic calculus to show that
effect handlers cannot be macro-expressed while preserving typeability either
by monadic reflection or by delimited control. We supplement our development
with a mechanised Abella formalisation.


title: Topological transcendence degree

abstract:
  Throughout the paper, an analytic field means a non-archimedean complete
real-valued one, and our main objective is to extend to these fields the basic
theory of transcendental extensions. One easily introduces a topological
analogue of the transcendence degree, but, surprisingly, it turns out that it
may behave very badly. For example, a particular case of a theorem of
Matignon-Reversat asserts that if $\mathrm{char}(k)>0$ then
$\widehat{k((t))^a}$ possesses non-invertible continuous $k$-endomorphisms, and
this implies that the topological transcendence degree is not additive in
towers. Nevertheless, we prove that in some aspects the topological
transcendence degree behaves reasonably, and we show by explicit
counter-examples that our positive results are pretty sharp. Applications to
types of points in Berkovich spaces and untilts of
$\widehat{\mathbf{F}_p((t))^a}$ are discussed.


title:
Doubly resonant photonic antenna for single infrared quantum dot imaging
  at telecommunication wavelengths

abstract:
  Colloidal Quantum dots (CQDs) are nowadays one of the cornerstones of modern
photonics as they have led to the emergence of new optoelectronic and
biomedical technologies. However, the full characterization of these quantum
emitters is currently restricted to the visible wavelengths and it remains a
key challenge to optically probe single CQDs operating in the infrared spectral
domain which is targeted by a growing number of applications. Here, we report
the first experimental detection and imaging at room temperature of single
infrared CQDs operating at telecommunication wavelengths. Imaging was done with
a doubly resonant bowtie nano-aperture antenna (BNA) written at the end of a
fiber nanoprobe, whose resonances spectrally fit the CQD absorption and
emission wavelengths. Direct near-field characterization of PbS CQDs reveal
individual nanocrystals with a spatial resolution of 75 nm (lambda/20) together
with their intrinsic 2D dipolar free-space emission properties and exciton
dynamics (blinking phenomenon). Because the doubly resonant BNA is strongly
transmissive at both the CQD absorption and emission wavelengths, we are able
to perform all-fiber nano-imaging with a standard 20 % efficiency InGaAs
avalanche photodiode (APD). Detection efficiency is predicted to be 3000 fold
larger than with a conventional circular aperture tip of the same transmission
area. Double resonance BNA fiber probes thus offer the possibility of exploring
extreme light-matter interaction in low band gap CQDs with current
plug-and-play detection techniques, opening up new avenues in the fields of
infrared light emitting devices, photodetectors, telecommunications,
bio-imaging and quantum information technology.


title: Effects of Social Ties in Knowledge Diffusion: case study on PLOS ONE

abstract:
  In order to capture the effects of social ties in knowledge diffusion, this
paper examines the publication network that emerges from the collaboration of
researchers, using citation information as means to estimate knowledge flow.
For this purpose, we analyzed the papers published in the PLOS ONE journal
finding strong evidence to support that the closer two authors are in the
co-authorship network, the larger the probability that knowledge flow will
occur between them. Moreover, we also found that when it comes to knowledge
diffusion, strong co-authorship proximity is more determinant than geographic
proximity.


title: Minkowski's question mark measure is UST--regular

abstract:
  We prove the recent conjecture that Minkowski's question mark measure is
regular, in the sense of Ullman-Stahl-Totik.


title: Push vs. Pull-Based Loop Fusion in Query Engines

abstract:
  Database query engines use pull-based or push-based approaches to avoid the
materialization of data across query operators. In this paper, we study these
two types of query engines in depth and present the limitations and advantages
of each engine. Similarly, the programming languages community has developed
loop fusion techniques to remove intermediate collections in the context of
collection programming. We draw parallels between the DB and PL communities by
demonstrating the connection between pipelined query engines and loop fusion
techniques. Based on this connection, we propose a new type of pull-based
engine, inspired by a loop fusion technique, which combines the benefits of
both approaches. Then we experimentally evaluate the various engines, in the
context of query compilation, for the first time in a fair environment,
eliminating the biasing impact of ancillary optimizations that have
traditionally only been used with one of the approaches. We show that for
realistic analytical workloads, there is no considerable advantage for either
form of pipelined query engine, as opposed to what recent research suggests.
Also, by using microbenchmarks we show that our proposed engine dominates the
existing engines by combining the benefits of both.


title: Quasi-three body systems - properties and scattering

abstract:
  We investigate systems of three mutually interacting particles with masses of
which the inner is much bigger than the intermediate and the latter is much
bigger than the outer. Then the three-body problem reduces to the two-body
scattering or structure of the light one in the field of the pseudo-nucleus
formed by two others. We calculate analytically the properties of considered
systems, such as the scattering cross-sections, hyperfine splitting, Auger
decay of exited states and Lamb shits, presenting them as expansions in powers
of the ratio of light to intermediate particle masses. This ratio is the small
parameter of the studied problems.


title:
Black hole hair formation in shift-symmetric generalised scalar-tensor
  gravity

abstract:
  A linear coupling between a scalar field and the Gauss-Bonnet invariant is
the only known interaction term between a scalar and the metric that: respects
shift symmetry; does not lead to higher order equations; inevitably introduces
black hole hair in asymptotically flat, 4-dimensional spacetimes. Here we focus
on the simplest theory that includes such a term and we explore the dynamical
formation of scalar hair. In particular, we work in the decoupling limit that
neglects the backreaction of the scalar onto the metric and evolve the scalar
configuration numerically in the background of a Schwarzschild black hole or a
collapsing dust star described by the Oppenheimer-Snyder solution. For all
types of initial data that we consider, the scalar relaxes at late times to the
known, static, analytic configuration that is associated with a hairy,
spherically symmetric black hole. This suggests that the corresponding black
hole solutions are indeed endpoints of collapse.


title:
Salty popcorn in a homogeneous low-dimensional toy model of holographic
  QCD

abstract:
  Recently, a homogeneous ansatz has been used to study cold dense nuclear
matter in the Sakai-Sugimoto model of holographic QCD. To justify this
homogeneous approximation we here investigate a homogeneous ansatz within a
low-dimensional toy version of Sakai-Sugimoto to study finite baryon density
configurations and compare it to full numerical solutions. We find the ansatz
corresponds to enforcing a dyon salt arrangement in which the soliton solutions
are split into half-soliton layers. Within this ansatz we find analogues of the
proposed baryonic popcorn transitions, in which solutions split into multiple
layers in the holographic direction. The homogeneous results are found to
qualitatively match the full numerical solutions, lending confidence to the
homogeneous approximations of the full Sakai-Sugimoto model. In addition, we
find exact compact solutions in the high density, flat space limit which
demonstrate the existence of further popcorn transitions to three layers and
beyond.


title: Ghosts of Order on the Frontier of Chaos

abstract:
  What kinds of motion can occur in classical mechanics? We address this
question by looking at the structures traced out by trajectories in phase
space; the most orderely, completely integrable systems, are charactrized by
phase trajectories confined to low-dimensional, invariant tori. The KAM theory
examines what happens to the tori when an integrable system is subjected to a
small perturbation and finds that, for small enough perturbations, most of them
survive.
  The KAM theory is mute on the suject of the disrupted tori, but, for two
dimensional systems, Aubry and Mather discovered an astonishing picture: the
broken tori are replaced by "cantori", tattered, Cantor-set remnants of the
original invariant curves. We seek to extend Aubry and Mather's picture to
higher dimensional systems and report two kinds of studies; both concern
perturbations of a completely integrable, four-dimensional symplectic map. In
the first study we compute some numerical approximations to Birkhoff periodic
orbits; sequences of such orbits should approximate any higher dimensional
analogs of the cantori. In the second study we prove converse KAM theorems;
that is, we use a combination of analytic arguments and rigorous,
machine-assisted computations to find perturbations so large that no KAM tori
survive. We are able to show that the last few of our Birkhoff orbits exist in
a regime where there are no tori.


title: On Kloosterman sums with multiplicative coefficients

abstract:
  The series of some new estimates for the sums of the type \[
S_{q}(x;f)\,=\,\mathop{{\sum}'}\limits_{n\leqslant x}f(n)e_{q}(an^{*}+bn) \] is
obtained. Here $q$ is a sufficiently large integer,
$\sqrt{q}(\log{q})\!\ll\!x\leqslant q$, $a,b$ are integers, $(a,q)=1$,
$e_{q}(v) = e^{2\pi iv/q}$, $f(n)$ is a multiplicative function, $nn^{*}\equiv
1 \pmod{q}$ and the prime sign means that $(n,q)=1$.


title:
Electronic structure, magnetism, and optical properties of orthorhombic
  GdFeO3 from first principles

abstract:
  Orthorhombic GdFeO$_3$ has attracted considerable attention in recent years
because its magnetic structure is similar to that in the well-known BiFeO$_3$
material. We investigate electronic structure, magnetism, and optical
properties of the orthorhombic GdFeO$_3$ in terms of density-functional-theory
calculations. The modified Becke-Johnson (mBJ) exchange potential is adopted to
improve on the description of the electronic structure. Our calculation show
that the G-type antiferromagnetic (G-AFM ordering of Fe spins) phase of
orthorhombic GdFeO$_3$ is stable compared to other magnetic phases. The
semiconductor gap calculated with mBJ, substantially larger than that with GGA,
is in good agreement with recent experimental values. Besides, we also
investigate effect of the spin-orbit coupling on the electronic structure, and
calculate with mBJ the complex dielectric functions and other optical functions
of photon energy. The magnetic exchange interactions are also investigated,
which gives a Neel temperature close to experimental observation. For
comparison towards supporting our results, we study the electronic structure of
rhombohedral (R3c) BiFeO$_3$ with mBJ. These lead to a satisfactory theoretical
understanding of the electronic structure, magnetism, and optical properties of
orthorhombic GdFeO$_3$ and can help elucidate electronic structures and optical
properties of other similar materials.


title: On the Connection Between Different Noise Structures for LPV-SS Models

abstract:
  Different representations to describe noise processes and finding connections
or equivalence between them have been part of active research for decades, in
particular for linear time-invariant case. In this paper the linear
parameter-varying (LPV) setting is addressed; starting with the connection
between an LPV state-space (SS) representation with a general noise structure
and the LPV-SS model in an innovation structure, i.e., the Kalman filter. More
specifically, the considered LPV-SS representation with general noise structure
has static, affine dependence on the scheduling signal; however, we show that
its companion innovation structure has a dynamic, rational dependency
structure. Following, we would like to highlight the consequences of
approximating this Kalman gain by a static, affine dependency structure. To
this end, firstly, we use the "fading memory" effect of the Kalman filter to
reason how the Kalman gain can be approximated to depend only on a partial
trajectory of the scheduling signal. This effect is shown by proving an
asymptotically decreasing error upper bound on the covariance matrix associated
to the innovation structure in case the covariance matrix is subjected to an
incorrect initialization or disturbance. Secondly, we show by an example that
an LPV-SS representation that has dynamical, rational dependency on the
scheduling signal can be transformed into static, affinely dependent
representation by introducing additional states. Therefore, an approximated
Kalman gain can, in some cases, be represented by a static, affine Kalman gain
at the cost of additional states.


title:
The GIRAFFE Inner Bulge Survey (GIBS) III. Metallicity distributions and
  kinematics of 26 Galactic bulge fields

abstract:
  Several recent studies have demonstrated that the Galactic bulge hosts two
components with different mean metallicities, and possibly different spatial
distribution and kinematics. As a consequence, both the metallicity
distribution and the radial velocity of bulge stars vary across different line
of sights. We present here the metallicity distribution function of red clump
stars in 26 fields spread across a wide area of the bulge, with special
emphasis on fields close to Galactic plane, at latitudes b=-2 and b=-1, that
were not explored before. This paper includes new metallicities from a sample
of about 5000 K giant stars, observed at spectral resolution R=6500, in the
Calcium II Triplet region. They are the main dataset of the GIRAFFE Inner Bulge
Survey. As part of the same survey we have previously published results for a
sample of about 600 K giant stars, at latitude b=-4 , derived from higher
resolution spectra (R=22,500). Results. The combined sample allows us to trace
and characterize the metal poor and metal rich bulge populations down to the
inner bulge. We present a density map for each of the two components. Contrary
to the expectations from previous works, we found the metal poor population to
be more centrally concentrated than the metal rich one, and with a more
axisymmetric spatial distribution. The metal rich population, on the other
hand, is arranged in a boxy distribution, consistent with an edge-on bar. By
coupling metallicities and radial velocities we show that the metal poor
population has a velocity dispersion that varies rather mildly with latitude.
On the contrary, the metal rich population has a low velocity dispersion far
from the plane (b=-8.5), but it has a steeper gradient with latitude, becoming
higher than the metal poor one in the innermost field (b=-1). [abridged]


title:
Viscous energy dissipation in slender channels with porous or
  semipermeable walls

abstract:
  We study the viscous dissipation in pipe flows in long channels with porous
or semipermeable walls, taking into account both the dissipation in the bulk of
the channel and in the pores. We give simple closed form expressions for the
dissipation in terms of the axially varying flow rate $Q(x)$ and the pressure
$p(x)$, generalizing the well known expression $\dot W=Q\,\Delta p$ for the
case of impenetrable walls with constant $Q$ and a pressure difference $\Delta
p$ between the ends of the pipe. When the pressure $p_0$ outside the pipe is
constant, the result is the straightforward generalization $\dot W=\Delta
\left[(p-p_0) \,Q\right]$. Finally, applications to osmotic flows are
considered.


title:
Quantum fluctuations in quasi-one-dimensional dipolar Bose-Einstein
  condensates

abstract:
  Recent experiments have revealed that beyond-mean-field corrections are much
more relevant in weakly-interacting dipolar condensates than in their
non-dipolar counterparts. We show that in quasi-one-dimensional geometries
quantum corrections in dipolar and non-dipolar condensates are strikingly
different due to the peculiar momentum dependence of the dipolar interactions.
The energy correction of the condensate presents not only a modified density
dependence, but it may even change from attractive to repulsive at a critical
density due to the surprising role played by the transversal directions. The
anomalous quantum correction translates into a strongly modified physics for
quantum-stabilized droplets and dipolar solitons. Moreover, and for similar
reasons, quantum corrections of three-body correlations, and hence of
three-body losses, are strongly modified by the dipolar interactions. This
intriguing physics can be readily probed in current experiments with magnetic
atoms.


title:
Complete spectral energy distribution of the hot, helium-rich white
  dwarf RX J0503.9-2854

abstract:
  In the line-of-sight toward the DO-type white dwarf RX J0503.9-2854, the
density of the interstellar medium (ISM) is very low, and thus the
contamination of the stellar spectrum almost negligible. This allows us to
identify many metal lines in a wide wavelength range from the extreme
ultraviolet to the near infrared. In previous spectral analyses, many metal
lines in the ultraviolet spectrum of RX J0503.9-2854 have been identified. A
complete line list of observed and identified lines is presented here. We
compared synthetic spectra that had been calculated from model atmospheres in
non-local thermodynamical equilibrium, with observations. In total, we
identified 1272 lines (279 of them were newly assigned) in the wavelength range
from the extreme ultraviolet to the near infrared. 287 lines remain
unidentified. A close inspection of the EUV shows that still no good fit to the
observed shape of the stellar continuum flux can be achieved although He, C, N,
O, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Mn, Fe, Cr, Ni Zn, Ga, Ge, As, Kr, Zr, Mo,
Sn, Xe, and Ba are included in the stellar atmosphere models. There are two
possible reasons for the deviation between observed and synthetic flux in the
EUV. Opacities from hitherto unconsidered elements in the model-atmosphere
calculation may be missing and/or the effective temperature is slightly lower
than previously determined.


title: 4d N=1 from 6d (1,0)

abstract:
  We study the geometry of 4d N=1 SCFT's arising from compactification of 6d
(1,0) SCFT's on a Riemann surface. We show that the conformal manifold of the
resulting theory is characterized, in addition to moduli of complex structure
of the Riemann surface, by the choice of a connection for a vector bundle on
the surface arising from flavor symmetries in 6d. We exemplify this by
considering the case of 4d N=1 SCFT's arising from M5 branes probing Z_k
singularity compactified on a Riemann surface. In particular, we study in
detail the four dimensional theories arising in the case of two M5 branes on
Z_2 singularity. We compute the conformal anomalies and indices of such
theories in 4d and find that they are consistent with expectations based on
anomaly and the moduli structure derived from the 6 dimensional perspective.


title: Lifshitz tails for the multi-particle continuous Anderson model

abstract:
  We consider the multi-particle Anderson model in the continuum and show that
under some mild assumptions on the inter-particle interaction and the external
potential, its lower spectral edge is almost surely constant and is the same
with that of the single-particle model. We then obtain the lifshitz asymptotics
for the multi-particle hamiltonian in the continuum near the bottom of the
spectrum.


title: Perturbations of spiky strings in flat spacetimes

abstract:
  Perturbations of a class of semiclassical strings known today as spiky
strings, are studied using the well-known Jacobi equations for small normal
deformations of an embedded timelike surface. It is shown that there exists
finite normal perturbations of the spiky string worldsheets embedded in a $2+1$
dimensional flat spacetime. Such perturbations lead to a rounding off of the
spikes, which, in a way, demonstrates the stable nature of the unperturbed
worldsheet. The same features appear for the dual spiky string solution and in
the spiky as well as their dual solutions in $3+1$ dimensional flat spacetime.
Our results are based on exact solutions of the corresponding Jacobi equations
which we obtain and use while constructing the profiles of the perturbed
configurations.


title:
Are gravitational constant measurement discrepancies linked to galaxy
  rotation curves ?

abstract:
  The discrepancies between recently reported experimental values of the
gravitational constant were analysed within an inertia interpretation of MOND
theory. According to this scenario the relative gravitational acceleration
between a test mass and an array of source masses determines the magnitude of
post Newtonian corrections at small magnitudes of acceleration. The analysis
was applied to one of the most advanced recent Cavendish-type experiment which
revealed an experimental value for the gravitational constant of 180 ppm above
the current CODATA value with more than five standard deviations significance.
A remarkable agreement between this discrepancy and the acceleration anomalies
inherent of galaxy rotation curves was found by a consistent extrapolation
within the framework of MOND. This surprising result suggests that the two
anomalies on totally different length scales may originate from the same
underlying physics.


title: Finite-Length Analysis of Frameless ALOHA

abstract:
  In this paper we present an exact finite-length analysis of frameless ALOHA
that is obtained through a dynamical programming approach. Monte Carlo
simulations are performed in order to verify the analysis. Two examples are
provided that illustrate how the analysis can be used to optimize the
parameters of frameless ALOHA. To the best of the knowledge of the authors,
this is the first contribution dealing with an exact finite-length
characterization of a protocol from the coded slotted ALOHA family of
protocols.


title: Multiactive objects and their applications

abstract:
  In order to tackle the development of concurrent and distributed systems, the
active object programming model provides a high-level abstraction to program
concurrent behaviours. There exists already a variety of active object
frameworks targeted at a large range of application domains: modelling,
verification, efficient execution. However, among these frameworks, very few
consider a multi-threaded execution of active objects. Introducing controlled
parallelism within active objects enables overcoming some of their limitations.
In this paper, we present a complete framework around the multi-active object
programming model. We present it through ProActive, the Java library that
offers multi-active objects, and through MultiASP, the programming language
that allows the formalisation of our developments. We then show how to compile
an active object language with cooperative multi-threading into multi-active
objects. This paper also presents different use cases and the development
support to illustrate the practical usability of our language. Formalisation of
our work provides the programmer with guarantees on the behaviour of the
multi-active object programming model and of the compiler.


title: Eigenvector statistics of the product of Ginibre matrices

abstract:
  We develop a method to calculate left-right eigenvector correlations of the
product of $m$ independent $N\times N$ complex Ginibre matrices. For
illustration, we present explicit analytical results for the vector overlap for
a couple of examples for small $m$ and $N$. We conjecture that the integrated
overlap between left and right eigenvectors is given by the formula $O = 1 +
(m/2)(N-1)$ and support this conjecture by analytical and numerical
calculations. We derive an analytical expression for the limiting correlation
density as $N\rightarrow \infty$ for the product of Ginibre matrices as well as
for the product of elliptic matrices. In the latter case, we find that the
correlation function is independent of the eccentricities of the elliptic laws.

categories: cond-mat.stat-mech math-ph math.MP stat.OT


title:
Differentiation method for localization of Compton edge in organic
  scintillation detectors

abstract:
  This paper, presents a simple method for accurate calibration of organic
scintillation detectors. The method is based on the fact that differentiating
the response function leads to accurate estimation of the Compton edge. The
differentiation method in addition to the location of the Compton edge, gives
insights into the parameters of the folded Gaussian function which is useful
for determination of the energy resolution. Moreover, it is observed that the
uncorrelated noise in the measurement of the response function does not impose
significant uncertainties in the evaluations. By simulation of the bounded
electrons and considering the Doppler effects, we are able to calculate a first
estimation for the intrinsic Doppler resolution of a plastic scintillator,
benefiting from the capability of the differentiation method.


title: Emission knots and polarization swings of swinging jets

abstract:
  Knots (emission features in jets of active galactic nuclei) often show
non-ballistic dynamics and variable emission/polarization properties. We model
these features as emission pattern propagating in a jet that carries helical
magnetic field and is launched along a changing direction. The model can
reproduce a wide range of phenomena observed in the motion of knots:
non-ballistic motion (both smooth and occasional sudden change of direction,
and/or oscillatory behavior), variable brightness, confinement of knots' motion
within an overlaying envelope. The model also reproduces smooth large
polarization angle swings, and at the same time allows for the seemingly random
behavior of synchrotron fluxes, polarization fraction and occasional $\pi/2$
polarization jumps.


title:
Distribution of ratio of two Wishart matrices and evaluation of
  cumulative probability by holonomic gradient method

abstract:
  We study the distribution of the ratio of two central Wishart matrices with
different covariance matrices. We first derive the density function of a
particular matrix form of the ratio and show that its cumulative distribution
function can be expressed in terms of the hypergeometric function 2F1 of a
matrix argument. Then we apply the holonomic gradient method for numerical
evaluation of the hypergeometric function. This approach enables us to compute
the power function of Roy's maximum root test for testing the equality of two
covariance matrices.


title: Group 1-cohomology is complemented

abstract:
  We show a structural property of cohomology with coefficients in an isometric
representation on a uniformly convex Banach space: if the cohomology group
$H^1(G,\pi)$ is reduced, then, up to an isomorphism, it is a closed
complemented, subspace of the space of cocycles and its complement is the
subspace of coboundaries.


title:
Simulating Organogenesis in COMSOL: Phase-Field Based Simulations of
  Embryonic Lung Branching Morphogenesis

abstract:
  Organogenesis has been studied for decades, but fundamental questions
regarding the control of growth and shape remain unsolved. We have recently
shown that of all proposed mathematical models only ligand-receptor based
Turing models successfully reproduce the experimentally determined growth
fields of the embryonic lung and thus provide a mechanism for growth control
during embryonic lung development. Turing models are based on at least two
coupled non-linear reaction-diffusion equations. In case of the lung model, at
least two distinct layers (mesenchyme and epithelium) need to be considered
that express different components (ligand and receptor, respectively). The
Arbitrary Lagrangian-Eulerian (ALE) method has previously been used to solve
this Turing system on growing and deforming (branching) domains, where
outgrowth occurs proportional to the strength of ligand-receptor signalling.
However, the ALE method requires mesh deformations that eventually limit its
use. Therefore, we incorporate the phase field method to simulate 3D embryonic
lung branching with COMSOL.


title: Domain Specific Distributed Search Engine Based on Semantic P2P Networks

abstract:
  This paper presents a distributed search engine based on semantic P2P
Networks. The user's computers join the domains in which user wants to share
information in semantic P2P networks which is domain specific virtual tree
(VIRGO ). Each user computer contains search engine which indexes the domain
specific information on local computer or Internet. We can get all search
information through P2P message provided by all joined computers. By companies'
effort, we have implemented a prototype of distributed search engine, which
demonstrates easily retrieving domain-related information provided by joined
computers .


title: Soft phonon driven orbital order in CaMn7O12

abstract:
  We use variable-temperature x-ray thermal diffuse scattering and inelastic
scattering to investigate the lattice dynamics in single crystals of
multiferroic CaMn7O12 which undergo a series of orbital and magnetic
transitions at low temperatures. Upon approaching the charge and orbital
ordering temperature To=250 K from above, we observe intense diffuse scattering
features and a pronounced optical phonon softening centered around the
superstructure reflections of the incommensurately modulated structure. The
phonon anomaly appears well above To and continuously increases upon cooling,
following a canonical power-law temperature dependence that confirms the
transition at To to be of second order and related to a soft-phonon lattice
instability. Microscopic mechanisms for the incommensurate charge and orbital
ordering based on competing interactions and on momentum dependent
electron-phonon coupling could both account for the observed extended momentum
width of the phonon softening. Our results highlight the importance of the
lattice interactions in the physics of this magnetically induced ferroelectric
system.


title:
Anharmonic particles: suppressing van der Waals forces by an external
  field

abstract:
  We study the classical thermal component of Casimir, or van der Waals, forces
between point particles with highly anharmonic dipole Hamiltonians when they
are subjected to an external electric field. Using a model for which the
individual dipole moments saturate in a strong field (a model that mimics the
charges in a neutral, perfectly conducting sphere), we find that the resulting
Casimir force depends strongly on the strength of the field, as demonstrated by
analytical results. For a certain angle between external field and center to
center axis, the fluctuation force can be tuned and suppressed to arbitrarily
small values. We compare the forces between these anharmonic particles to those
between harmonic ones, and also provide a simple formula for asymptotically
large external fields, which we expect to be generally valid for the case of
saturating dipole moments.


title:
Noise-induced interspike interval correlations and spike train
  regularization in spike-triggered adapting neurons

abstract:
  Spike generation in neurons produces a temporal point process, whose
statistics is governed by intrinsic phenomena and the external incoming inputs
to be coded. In particular, spike-evoked adaptation currents support a slow
temporal process that conditions spiking probability at the present time
according to past activity. In this work, we study the statistics of interspike
interval correlations arising in such non-renewal spike trains, for a neuron
model that reproduces different spike modes in a small adaptation scenario. We
found that correlations are stronger as the neuron fires at a particular firing
rate, which is defined by the adaptation process. When set in a subthreshold
regime, the neuron may sustain this particular firing rate, and thus induce
correlations, by noise. Given that, in this regime, interspike intervals are
negatively correlated at any lag, this effect surprisingly implies a reduction
in the variability of the spike count statistics at a finite noise intensity.


title:
Convergence and efficiency of adaptive importance sampling techniques
  with partial biasing

abstract:
  We consider a generalization of the discrete-time Self Healing Umbrella
Sampling method, which is an adaptive importance technique useful to sample
multimodal target distributions. The importance function is based on the
weights (namely the relative probabilities) of disjoint sets which form a
partition of the space. These weights are unknown but are learnt on the fly
yielding an adaptive algorithm. In the context of computational statistical
physics, the logarithm of these weights is, up to a multiplicative constant,
the free energy, and the discrete valued function defining the partition is
called the collective variable. The algorithm falls into the general class of
Wang-Landau type methods, and is a generalization of the original Self Healing
Umbrella Sampling method in two ways: (i) the updating strategy leads to a
larger penalization strength of already visited sets in order to escape more
quickly from metastable states, and (ii) the target distribution is biased
using only a fraction of the free energy, in order to increase the effective
sample size and reduce the variance of importance sampling estimators. The
algorithm can also be seen as a generalization of well-tempered metadynamics.
We prove the convergence of the algorithm and analyze numerically its
efficiency on a toy example.


title:
Branching processes seen from their extinction time via path
  decompositions of reflected L\'evy processes

abstract:
  We consider a spectrally positive L\'evy process $X$ that does not drift to
$+\infty$, viewed as coding for the genealogical structure of a (sub)critical
branching process, in the sense of a contour or exploration process
\cite{GaJa98,Lam10}. We denote by $I$ the past infimum process defined for each
$t\geq 0$ by $I_t:= \inf_{[0,t]} X$ and we let $\gamma$ be the unique time at
which the excursion of the reflected process $X-I$ away from 0 attains its
supremum. We prove that the pre-$\gamma$ and the post-$\gamma$ subpaths of this
excursion are invariant under space-time reversal, which has several other
consequences in terms of duality for excursions of L\'evy processes. It implies
in particular that the local time process of this excursion is also invariant
when seen backward from its height. As a corollary, we obtain that some
(sub)critical branching processes such as the (sub)critical Crump-Mode-Jagers
(CMJ) processes and the excursion away from 0 of the critical Feller diffusion,
which is the width process of the continuum random tree, are invariant under
time reversal from their extinction time.


title: Controllability of quasi-linear Hamiltonian NLS equations

abstract:
  We prove internal controllability in arbitrary time, for small data, for
quasi-linear Hamiltonian NLS equations on the circle. We use a procedure of
reduction to constant coefficients up to order zero and HUM method to prove the
controllability of the linearized problem. Then we apply a
Nash-Moser-H\"ormander implicit function theorem as a black box.


title: Optimal Universal Uncertainty Relations

abstract:
  We study universal uncertainty relations and present a method called joint
probability distribution diagram to improve the majorization bounds constructed
independently in [Phys. Rev. Lett. 111, 230401 (2013)] and [J. Phys. A. 46,
272002 (2013)]. The results give rise to state independent uncertainty
relations satisfied by any nonnegative Schur-concave functions. On the other
hand, a remarkable recent result of entropic uncertainty relation is the
direct-sum majorization relation. In this paper, we illustrate our bounds by
showing how they provide a complement to that in [Phys. Rev. A. 89, 052115
(2014)].


title:
A non-integrated hypersurface defect relation for meromorphic maps over
  complete K\"ahler manifolds into projective algebraic varieties

abstract:
  In this paper, a non-integrated defect relation for meromorphic maps from
complete K\"ahler manifolds $M$ into smooth projective algebraic varieties $V$
intersecting hypersurfaces located in $k$-subgeneral position is proved. The
novelty of this result lies in that both the upper bound and the truncation
level of our defect relation depend only on $k$, $\dim_{\,\mathbb{C}}(V)$ and
the degrees of the hypersurfaces considered. In addition, this defect relation
recovers Hirotaka Fujimoto [Theorem 1.1; MR0884636 (88m:32049); Japan. J. Math.
(N.S.) 11 (1985), no. 2, 233-264.] when subjected to the same conditions.


title:
FORC+: A method for separating reversible from irreversible behavior
  using first order reversal curves

abstract:
  First Order Reversal Curves (FORCs) have been used for a number of years for
the extraction of information from magnetization measurements. The results are
most unambiguous for irreversible processes -- for a collection of Preisach
hysterons, one gets a "FORC distribution" $\rho(H_{down},H_{up})$, the number
of hysterons with given downward \& upward reversal fields. There have been
many proposals for dealing with reversible behavior, usually involving
inserting it somehow into the irreversible FORC distribution. Here we will try
to do the opposite, to separate them into another function which we will call
the (reversible) "saturation field distribution", which is identically zero for
a completely irreversible system of hysterons, while the irreversible FORC
distribution is identically zero for a reversible system. Thus in a system with
both purely reversible and purely irreversible components, such as
single-domain Stoner-Wohlfarth particles with hard or easy axis along the
field, this approach cleanly separates them. For more complicated systems, as
with conventional FORC distributions, it at least provides a "signature" making
it possible to identify microscopic models that might give a particular pair of
irreversible and reversible distributions.


title:
Spin-Orbit Torque Efficiency in Compensated Ferrimagnetic Cobalt-Terbium
  Alloys

abstract:
  Despite the potential advantages of information storage in
antiferromagnetically coupled materials, it remains unclear whether one can
control the magnetic moment orientation efficiently because of the cancelled
magnetic moment. Here, we report spin-orbit torque induced magnetization
switching of ferrimagnetic Co1-xTbx films with perpendicular magnetic
anisotropy. Current induced switching is demonstrated in all of the studied
film compositions, including those near the magnetization compensation point.
The spin-orbit torque induced effective field is further quantified in the
domain wall motion regime. A divergent behavior that scales with the inverse of
magnetic moment is confirmed close to the compensation point, which is
consistent with angular momentum conservation. Moreover, we also quantify the
Dzyaloshinskii-Moriya interaction energy in the Ta/Co1-xTbx system and we find
that the energy density increases as a function of the Tb concentration. The
demonstrated spin-orbit torque switching, in combination with the fast magnetic
dynamics and minimal net magnetization of ferrimagnetic alloys, promises
spintronic devices that are faster and with higher density than traditional
ferromagnetic systems.


title:
A Conceptual Development of Quench Prediction App build on LSTM and ELQA
  framework

abstract:
  This article presents a development of web application for quench prediction
in \gls{te-mpe-ee} at CERN. The authors describe an ELectrical Quality
Assurance (ELQA) framework, a platform which was designed for rapid development
of web integrated data analysis applications for different analysis needed
during the hardware commissioning of the Large Hadron Collider (LHC). In second
part the article describes a research carried out with the data collected from
Quench Detection System by means of using an LSTM recurrent neural network. The
article discusses and presents a conceptual work of implementing quench
prediction application for \gls{te-mpe-ee} based on the ELQA and quench
prediction algorithm.


title:
Sufficient conditions for existence of positive periodic solution of a
  generalized nonresident computer virus model

abstract:
  In this paper, we introduce a nonresident computer virus model and prove the
existence of at least one positive periodic solution. The proposed model is
based on a biological approach and is obtained by considering that all rates
(rates that the computers are disconnected from the Internet, the rate that the
computers are cured, etc) are time dependent real functions. Assuming that the
initial condition is a positive vector and the coefficients are positive
$\omega-$periodic and applying the topological degree arguments we deduce that
generalized nonresident computer virus model has at least one positive
$\omega-$periodic solution. The proof consists of two big parts. First, an
appropriate change of variable which conserves the periodicity property and
implies the positive behavior. Second, a reformulation of transformed system as
an operator equation which is analyzed by applying the continuation theorem of
the coincidence degree theory.


title:
A breather construction for a semilinear curl-curl wave equation with
  radially symmetric coefficients

abstract:
  We consider the semilinear curl-curl wave equation $s(x) \partial_t^2 U
+\nabla\times\nabla\times U + q(x) U \pm V(x) |U|^{p-1} U = 0 \mbox{ for }
(x,t)\in \mathbb{R}^3\times\mathbb{R}$. For any $p>1$ we prove the existence of
time-periodic spatially localized real-valued solutions (breathers) both for
the $+$ and the $-$ case under slightly different hypotheses. Our solutions are
classical solutions that are radially symmetric in space and decay
exponentially to $0$ as $|x|\to \infty$. Our method is based on the fact that
gradient fields of radially symmetric functions are annihilated by the
curl-curl operator. Consequently, the semilinear wave equation is reduced to an
ODE with $r=|x|$ as a parameter. This ODE can be efficiently analyzed in phase
space. As a side effect of our analysis, we obtain not only one but a full
continuum of phase-shifted breathers $U(x,t+a(x))$, where $U$ is a particular
breather and $a:\mathbb{R}^3\to\mathbb{R}$ an arbitrary radially symmetric
$C^2$-function.


title: Judging a Book By its Cover

abstract:
  Book covers communicate information to potential readers, but can that same
information be learned by computers? We propose using a deep Convolutional
Neural Network (CNN) to predict the genre of a book based on the visual clues
provided by its cover. The purpose of this research is to investigate whether
relationships between books and their covers can be learned. However,
determining the genre of a book is a difficult task because covers can be
ambiguous and genres can be overarching. Despite this, we show that a CNN can
extract features and learn underlying design rules set by the designer to
define a genre. Using machine learning, we can bring the large amount of
resources available to the book cover design process. In addition, we present a
new challenging dataset that can be used for many pattern recognition tasks.


title: Nested Distributed Model Predictive Control

abstract:
  We propose a distributed model predictive control approach for linear
time-invariant systems coupled via dynamics. The proposed approach uses the
tube MPC concept for robustness to handle the disturbances induced by mutual
interactions between subsystems; however, the main novelty here is to replace
the conventional linear disturbance rejection controller with a second MPC
controller, as is done in tube-based nonlinear MPC. In the distributed setting,
this has the advantages that the disturbance rejection controller is able to
consider the plans of neighbours, and the reliance on explicit robust invariant
sets is removed.


title: Controlled-phase gate for photons based on stationary light

abstract:
  We propose a method to induce strong effective interactions between photons
mediated by an atomic ensemble. To achieve this, we use the so-called
stationary light effect to enhance the interaction. Regardless of the
single-atom coupling to light, the interaction strength between the photons can
be enhanced by increasing the total number of atoms. For sufficiently many
atoms, the setup can be viable as a controlled-phase gate for photons. We
derive analytical expressions for the fidelities for two modes of gate
operation: deterministic and heralded conditioned on the presence of two
photons at the output.


title:
Hybrid discontinuous Galerkin discretisation and domain decomposition
  preconditioners for the Stokes problem

abstract:
  Solving the Stokes equation by an optimal domain decomposition method derived
algebraically involves the use of non standard interface conditions whose
discretisation is not trivial. For this reason the use of approximation methods
such as hybrid discontinuous Galerkin appears as an appropriate strategy: on
the one hand they provide the best compromise in terms of the number of degrees
of freedom in between standard continuous and discontinuous Galerkin methods,
and on the other hand the degrees of freedom used in the non standard interface
conditions are naturally defined at the boundary between elements. In this
paper we introduce the coupling between a well chosen discretisation method
(hybrid discontinuous Galerkin) and a novel and efficient domain decomposition
method to solve the Stokes system. We present the detailed analysis of the
hybrid discontinuous Galerkin method for the Stokes problem with non standard
boundary conditions. This analysis is supported by numerical evidence. In
addition, the advantage of the new preconditioners over more classical choices
is also supported by numerical experiments.


title: On binary cubic and quartic forms

abstract:
  In this paper we determine the group of rational automorphisms of binary
cubic and quartic forms with integer coefficients and non-zero discriminant in
terms of certain quadratic covariants of cubic and quartic forms. This allows
one to give precise asymptotic formulae for the number of integers in an
interval representable by a binary cubic or quartic form and extends work of
Hooley. Further, we give the field of definition of lines contained in certain
cubic and quartic surfaces related to binary cubic and quartic forms.


title: Computability in Basic Quantum Mechanics

abstract:
  The basic notions of quantum mechanics are formulated in terms of separable
infinite dimensional Hilbert space $\mathcal{H}$. In terms of the Hilbert
lattice $\mathcal{L}$ of closed linear subspaces of $\mathcal{H}$ the notions
of state and observable can be formulated as kinds of measures as in [21]. The
aim of this paper is to show that there is a good notion of computability for
these data structures in the sense of Weihrauch's Type Two Effectivity (TTE)
[26].
  Instead of explicitly exhibiting admissible representations for the data
types under consideration we show that they do live within the category
$\mathbf{QCB}_0$ which is equivalent to the category $\mathbf{AdmRep}$ of
admissible representations and continuously realizable maps between them. For
this purpose in case of observables we have to replace measures by valuations
which allows us to prove an effective version of von Neumann's Spectral
Theorem.


title: Extremal regular graphs: independent sets and graph homomorphisms

abstract:
  This survey concerns regular graphs that are extremal with respect to the
number of independent sets, and more generally, graph homomorphisms. More
precisely, in the family of of $d$-regular graphs, which graph $G$
maximizes/minimizes the quantity $i(G)^{1/v(G)}$, the number of independent
sets in $G$ normalized exponentially by the size of $G$? What if $i(G)$ is
replaced by some other graph parameter? We review existing techniques,
highlight some exciting recent developments, and discuss open problems and
conjectures for future research.


title:
Robust exponential convergence of hp-FEM in balanced norms for
  singularly perturbed reaction-diffusion problems: corner domains

abstract:
  The hp-version of the finite element method is applied to singularly
perturbed reaction-diffusion type equations on polygonal domains. The solution
exhibits boundary layers as well as corner layers. On a class of meshes that
are suitable refined near the boundary and the corners, robust exponential
convergence (in the polynomial degree) is shown in both a balanced norm and the
maximum norm.


title: Practical Privacy in WDM Networks with All-Optical Layered Encryption

abstract:
  Privacy in form of anonymous communication could be comparably both faster
and harder to break in optical routers than in today's anonymous IP networks
based on The Onion Routing (Tor). Implementing the practical privacy
alloptically,however, is not straightforward, as it requires key generation in
each anonymization node to avoid distribution of long keys, and layered
encryption, both at the optical line rate. Due to the unavailability of
cryptographically strong optical key generation and encryption components, not
only a layered encryption is a challenge, but an optical encryption in general.
In this paper, we address the challenges of optical anonymous networking for
the first time from the system's perspective, and discuss options for practical
implementation of all-optical layered encryption. To this end, we propose an
optical anonymization component realized with the state-of-the-art optical XOR
logic and optical Linear Feedback Shift Registers (oLFSRs). Given that LFSR
alone is known for its weak cryptographic security due to its linear
properties, we propose an implementation with parallel oLFSRs and analyze the
resulting computational security. The results show that proposed optical
anonymization component is promising as it can be practically realized to
provide a high computational security against deanonymization (privacy) attack.


title: Infinitesimally extremal Beltrami differentials of non-landslide type

abstract:
  In this paper, it is shown that there are infinitely many extremal Beltrami
differentials of non-landside type and non-constant modulus in an infinitesimal
equivalence class unless the class contains a unique extremal.


title: Black holes in Einstein-Gau\ss -Bonnet-dilaton theory

abstract:
  Generalizations of the Schwarzschild and Kerr black holes are discussed in an
astrophysically viable generalized theory of gravity, which includes higher
curvature corrections in the form of the Gauss-Bonnet term, coupled to a
dilaton. The angular momentum of these black holes can slightly exceed the Kerr
bound. The location and the orbital frequency of particles in their innermost
stable circular orbits can deviate significantly from the respective Kerr
values. Study of the quasinormal modes of the static black holes gives strong
evidence that they are mode stable against polar and axial perturbations.
Future gravitational wave observations should improve the current bound on the
Gauss-Bonnet coupling constant, based on observations of the low-mass x-ray
binary A 0620-00.


title:
Decentralized Power Control for Slotted Spread Spectrum Aloha with
  Successive Interference Cancellation

abstract:
  In this paper, we study slotted Spread Spectrum Aloha with Successive
Interference Cancellation at the receiver over a Gaussian channel. We consider
a decentralized power control setting in which each user chooses its transmit
power independently at random according to a power distribution with continuous
support. In this setting, we derive an analytical expression for the expected
interference power experienced by a user. This allows us to derive analytically
the power distribution that, during the Successive Interference Cancellation
process leads to a constant signal to noise plus interference ratio for all
users. We consider both perfect and imperfect interference cancellation.


title: On viscosity and weak solutions for non-homogeneous p-Laplace equations

abstract:
  In this manuscript we study the relation between viscosity and weak solutions
for non-homogeneous p-Laplace equations with lower order term depending on $x$,
$u$ and $\nabla u$. More precisely, we prove that any locally bounded viscosity
solution constitutes a weak solution, extending previous results by Juutinen,
Lindqvist and Manfredi on the homogeneous case, and Julin and Juutinen for a
linear right hand side. Moreover, we provide a converse statement in the full
case under extra assumptions on the regularity of the solutions.


title:
Large-time asymptotic behavior of the infinite system of harmonic
  oscillators

abstract:
  The mixed initial-boundary value problem for infinite one-dimensional chain
of harmonic oscillators on the half-line is considered. We study the large time
behavior of solutions and derive the dispersive bounds.


title:
Searches for invisible decays of the Higgs boson in pp collisions at
  sqrt(s) = 7, 8, and 13 TeV

abstract:
  Searches for invisible decays of the Higgs boson are presented. The data
collected with the CMS detector at the LHC correspond to integrated
luminosities of 5.1, 19.7, and 2.3 inverse femtobarns at centre-of-mass
energies of 7, 8, and 13 TeV, respectively. The search channels target Higgs
boson production via gluon fusion, vector boson fusion, and in association with
a vector boson. Upper limits are placed on the branching fraction of the Higgs
boson decay to invisible particles, as a function of the assumed production
cross sections. The combination of all channels, assuming standard model
production, yields an observed (expected) upper limit on the invisible
branching fraction of 0.24 (0.23) at the 95% confidence level. The results are
also interpreted in the context of Higgs-portal dark matter models.


title: Problems and Progress in Covariant High Spin Description

abstract:
  A universal description of particles with spins j greater or equal one ,
transforming in (j,0)+(0,j), is developed by means of representation specific
second order differential wave equations without auxiliary conditions and in
covariant bases such as Lorentz tensors for bosons, Lorentz-tensors with Dirac
spinor components for fermions, or, within the basis of the more fundamental
Weyl-Van-der-Waerden sl(2,C) spinor-tensors. At the root of the method, which
is free from the pathologies suffered by the traditional approaches, are
projectors constructed from the Casimir invariants of the spin-Lorentz group,
and the group of translations in the Minkowski space time.


title:
Radiation reaction induced spiral attractors in ultra-intense colliding
  laser beams

abstract:
  The radiation reaction effects on electron dynamics in counter-propagating
circularly polarized laser beams are investigated through the linearization
theorem and the results are in great agreement with numeric solutions. For the
first time, the properties of fixed points in electron phase-space were
analyzed with linear stability theory, showing that center nodes will become
attractors if the classical radiation reaction is considered. Electron dynamics
are significantly affected by the properties of the fixed points and the
electron phase-space densities are found to be increasing exponentially near
the attractors. The density growth rates are derived theoretically and further
verified by particle-in-cell simulations, which can be detected in experiments
to explore the effects of radiation reaction qualitatively. The attractor can
also facilitate to realize a series of nanometer-scaled flying electron slices
via adjusting the colliding laser frequencies.


title: Revenue Maximizing Envy-Free Pricing in Matching Markets with Budgets

abstract:
  We study envy-free pricing mechanisms in matching markets with $m$ items and
$n$ budget constrained buyers. Each buyer is interested in a subset of the
items on sale, and she appraises at some single-value every item in her
preference-set. Moreover, each buyer has a budget that constraints the maximum
affordable payment, while she aims to obtain as many items as possible of her
preference-set. Our goal is to compute an envy-free pricing allocation that
maximizes the revenue, i.e., the total payment charged to the buyers. This
pricing problem is hard to approximate better than $\Omega({\rm min}
\{n,m\}^{1/2-\epsilon})$ for any $\epsilon>0$, unless $P=NP$. The hardness
result is due to the presence of the matching constraints given that the
simpler multi-unit case can be approximated up to a constant factor of $2$. The
goal of this paper is to circumvent the hardness result by restricting
ourselves to specific settings of valuations and budgets. Two particularly
significant scenarios are: each buyer has a budget that is greater than her
single-value valuation, and each buyer has a budget that is lower than her
single-value valuation. Surprisingly, in both scenarios we are able to achieve
a $1/4$-approximation to the optimal envy-free revenue. The algorithms utilize
a novel version of the Ausebel ascending price auction. These results may
suggest that, although it is difficult to approximate the optimal revenue in
general, ascending price auctions could achieve relatively good revenue in most
of the practical settings.


title:
Inconsistency of the interactions between pseudoscalar, spinor and
  Rarita-Schwinger fields

abstract:
  We perform the Dirac quantization of RS fields interacting with a spinor and
the first derivative of a pseudoscalar field. We achieve the calculations for
two forms of this interaction: first we review the conventional coupling of
lowest derivative order, reproducing the well known inconsistencies in its
anticommutator algebra. Then, we perform the analysis on the next order term
popularly known as spin 3/2 gauge invariant interaction, which is claimed to be
free of these inconsistencies. Nevertheless we find that the direct application
of the Dirac formalism leads to inconsistencies in complete analogy to the
previous case. This is of high relevance in the particle phenomenology field,
where these interactions are used to interpret experimental data involving
Delta(1232) resonances.


title: Sort well with energy-constrained comparisons

abstract:
  We study very simple sorting algorithms based on a probabilistic comparator
model. In our model, errors in comparing two elements are due to (1) the energy
or effort put in the comparison and (2) the difference between the compared
elements. Such algorithms keep comparing pairs of randomly chosen elements, and
they correspond to Markovian processes. The study of these Markov chains
reveals an interesting phenomenon. Namely, in several cases, the algorithm
which repeatedly compares only adjacent elements is better than the one making
arbitrary comparisons: on the long-run, the former algorithm produces sequences
that are "better sorted". The analysis of the underlying Markov chain poses new
interesting questions as the latter algorithm yields a non-reversible chain and
therefore its stationary distribution seems difficult to calculate explicitly.


title:
Kirillov-Reshetikhin crystals $B^{1,s}$ for $\widehat{\mathfrak{sl}}_n$
  using Nakajima monomials

abstract:
  We give a realization of the Kirillov--Reshetikhin crystal $B^{1,s}$ using
Nakajima monomials for $\widehat{\mathfrak{sl}}_n$ using the crystal structure
given by Kashiwara. We describe the tensor product $\bigotimes_{i=1}^N
B^{1,s_i}$ in terms of a shift of indices, allowing us to recover the Kyoto
path model. Additionally, we give a model for the KR crystals $B^{r,1}$ using
Nakajima monomials.


title: Sentiment Analysis of Twitter Data for Predicting Stock Market Movements

abstract:
  Predicting stock market movements is a well-known problem of interest.
Now-a-days social media is perfectly representing the public sentiment and
opinion about current events. Especially, twitter has attracted a lot of
attention from researchers for studying the public sentiments. Stock market
prediction on the basis of public sentiments expressed on twitter has been an
intriguing field of research. Previous studies have concluded that the
aggregate public mood collected from twitter may well be correlated with Dow
Jones Industrial Average Index (DJIA). The thesis of this work is to observe
how well the changes in stock prices of a company, the rises and falls, are
correlated with the public opinions being expressed in tweets about that
company. Understanding author's opinion from a piece of text is the objective
of sentiment analysis. The present paper have employed two different textual
representations, Word2vec and N-gram, for analyzing the public sentiments in
tweets. In this paper, we have applied sentiment analysis and supervised
machine learning principles to the tweets extracted from twitter and analyze
the correlation between stock market movements of a company and sentiments in
tweets. In an elaborate way, positive news and tweets in social media about a
company would definitely encourage people to invest in the stocks of that
company and as a result the stock price of that company would increase. At the
end of the paper, it is shown that a strong correlation exists between the rise
and falls in stock prices with the public sentiments in tweets.


title:
Text Segmentation using Named Entity Recognition and Co-reference
  Resolution in English and Greek Texts

abstract:
  In this paper we examine the benefit of performing named entity recognition
(NER) and co-reference resolution to an English and a Greek corpus used for
text segmentation. The aim here is to examine whether the combination of text
segmentation and information extraction can be beneficial for the
identification of the various topics that appear in a document. NER was
performed manually in the English corpus and was compared with the output
produced by publicly available annotation tools while, an already existing tool
was used for the Greek corpus. Produced annotations from both corpora were
manually corrected and enriched to cover four types of named entities.
Co-reference resolution i.e., substitution of every reference of the same
instance with the same named entity identifier was subsequently performed. The
evaluation, using five text segmentation algorithms for the English corpus and
four for the Greek corpus leads to the conclusion that, the benefit highly
depends on the segment's topic, the number of named entity instances appearing
in it, as well as the segment's length.


title:
High resolution He I 10830 \AA\ narrow-band imaging of an M-class flare.
  I - analysis of sunspot dynamics during flaring

abstract:
  In this paper, we report our first-step results of high resolution
He\,\textsc{i} 10830 \AA\ narrow-band imaging (bandpass: 0.5 {\AA}) of an M1.8
class two-ribbon flare on July 5, 2012. The flare was observed with the 1.6
meter aperture New Solar Telescope at Big Bear Solar Observatory. For this
unique data set, sunspot dynamics during flaring were analyzed for the first
time. By directly imaging the upper chromosphere, running penumbral waves are
clearly seen as an outward extension of umbral flashes, both take the form of
absorption in the 10830 \AA\ narrow-band images. From a space-time image made
of a slit cutting across a flare ribbon and the sunspot, we find that the dark
lanes for umbral flashes and penumbral waves are obviously broadened after the
flare. The most prominent feature is the sudden appearance of an oscillating
absorption strip inside the ribbon when it sweeps into the sunspot's penumbral
and umbral regions. During each oscillation, outwardly propagating umbral
flashes and subsequent penumbral waves rush out into the inwardly sweeping
ribbon, followed by a returning of the absorption strip with similar speed. We
tentatively explain the phenomena as the result of a sudden increase in the
density of ortho-Helium atoms in the area of the sunspot being excited by the
flare's EUV illumination. This explanation is based on the observation that
10830 \AA\ absorption around the sunspot area gets enhanced during the flare.
Nevertheless, questions are still open and we need further well-devised
observations to investigate the behavior of sunspot dynamics during flares.


title:
A comprehensive long term study of the radio and X-ray Variability of
  NGC 4051 Paper II

abstract:
  The origin of the low luminosity radio emission in radio-quiet AGN, is
unknown. The detection of a positive correlation between the radio and X-ray
emission would imply a jet-like origin, similar to that seen in `hard state'
X-ray binary systems. In our previous work, we found no believable radio
variability in the well known X-ray bright Seyfert 1 galaxy NGC 4051, despite
large amplitude X-ray variability. In this study we have carefully re-analysed
radio and X-ray observations using the same methods as our previous work, we
again find no evidence for core radio variability. In direct contrast to our
findings, another study claim significant radio variability and a distinctive
anti-correlation between radio and X-ray data for the same source. The other
study report only integral flux values and do not consider the effect of the
changing array on the synthesised beam. In both our studies of NGC 4051 we have
taken great care to account for the effect that the changing beam size has on
the measured radio flux and as a result we are confident that our method gives
more accurate values for the intrinsic core radio flux. However, the lack of
radio variability we find is hard to reconcile because radio images of NGC 4051
do show jet-like structure. We suggest that the radio structures observed are
likely the result of a previous period of higher radio activity and that the
current level of radio emission from a compact nuclear jet is low.