title:
Simulation of Electric Double Layers around Charged Colloids in Aqueous
  Solution of Variable Permittivity

abstract:
  The ion distribution around charged colloids in solution has been
investigated intensely during the last decade. However, few theoretical
approaches have included the influence of variation in the dielectric
permittivity within the system, let alone in the surrounding solvent. In this
article, we introduce two relatively new methods that can solve the Poisson
equation for systems with varying permittivity. The harmonic interpolation
method (HIM) approximately solves the Green's function in terms of a spherical
harmonics series, and thus provides analytical ion-ion potentials for the
Hamiltonian of charged systems. The Maxwell Equations Molecular Dynamics (MEMD)
algorithm features a local approach to electrostatics, allowing for arbitrary
local changes of the dielectric constant. We show that the results of both
methods are in very good agreement. We also found that the renormalized charge
of the colloid, and with it the effective far field interaction, significantly
changes if the dielectric properties within the vicinity of the colloid are
changed.


title: Blind Denoising with Random Greedy Pursuits

abstract:
  Denoising methods require some assumptions about the signal of interest and
the noise. While most denoising procedures require some knowledge about the
noise level, which may be unknown in practice, here we assume that the signal
expansion in a given dictionary has a distribution that is more heavy-tailed
than the noise. We show how this hypothesis leads to a stopping criterion for
greedy pursuit algorithms which is independent from the noise level. Inspired
by the success of ensemble methods in machine learning, we propose a strategy
to reduce the variance of greedy estimates by averaging pursuits obtained from
randomly subsampled dictionaries. We call this denoising procedure Blind Random
Pursuit Denoising (BIRD). We offer a generalization to multidimensional
signals, with a structured sparse model (S-BIRD). The relevance of this
approach is demonstrated on synthetic and experimental MEG signals where,
without any parameter tuning, BIRD outperforms state-of-the-art algorithms even
when they are informed by the noise level. Code is available to reproduce all
experiments.


title: Tunable band gap in germanene by surface adsorption

abstract:
  Opening a sizable band gap in the zero-gap germanene without heavy loss of
carrier mobility is a key issue for its application in nanoelectronic devices
such as high-performance field effect transistors (FETs) operating at room
temperature. Using the first-principles calculations, we find a band gap is
opened at the Dirac point in germanene by single-side adsorption of alkali
metal (AM) atoms. This band gap is tunable by varying the coverage and the
species of AM atoms, ranging from 0.02 to 0.31 eV, and the maximum global band
gap is 0.26 eV. Since the effective masses of electrons and holes in germanene
near the Dirac point after surface adsorption (ranging from 0.005 to 0.106 me)
are small, the carrier mobility is expected not to degrade much. Therefore
germanene is a potential candidate of effective FET channel operating at room
temperature upon surface adsorption.


title:
Planck intermediate results. XVII. Emission of dust in the diffuse
  interstellar medium from the far-infrared to microwave frequencies

abstract:
  The dust-HI correlation is used to characterize the emission properties of
dust in the diffuse interstellar medium. We cross-correlate sky maps from
Planck, WMAP, and DIRBE, at 17 frequencies from 23 to 3000 GHz, with the Parkes
survey of the 21-cm line emission of neutral atomic hydrogen, over a contiguous
area of 7500 deg$^2$ centred on the southern Galactic pole. Our analysis yields
four specific results. (1) The dust temperature is observed to be
anti-correlated with the dust emissivity and opacity. We interpret this result
as evidence for dust evolution within the diffuse ISM. The mean dust opacity is
measured to be $(7.1 \pm 0.6) 10^{-27} cm^2/H \times (\nu/353\,
GHz)^{1.53\pm0.03}$ for $100 < \nu <353$GHz. (2) We map the spectral index of
dust emission at millimetre wavelengths, which is remarkably constant at
$\beta_{mm} = 1.51\pm 0.13$. We compare it with the far infrared spectral index
beta_FIR derived from greybody fits at higher frequencies, and find a
systematic difference, $\beta_{mm}-\beta_{FIR} = -0.15$, which suggests that
the dust SED flattens at $\nu < 353\,$GHz. (3) We present spectral fits of the
microwave emission correlated with HI from 23 to 353 GHz, which separate dust
and anomalous microwave emission. The flattening of the dust SED can be
accounted for with an additional component with a blackbody spectrum, which
accounts for $(26 \pm 6)$% of the dust emission at 100 GHz and could represent
magnetic dipole emission. Alternatively, it could account for an increasing
contribution of carbon dust, or a flattening of the emissivity of amorphous
silicates, at millimetre wavelengths. These interpretations make different
predictions for the dust polarization SED. (4) We identify a Galactic
contribution to the residuals of the dust-HI correlation, which we model with
variations of the dust emissivity on angular scales smaller than that of our
correlation analysis.


title:
Estimations of local thermal impact on living organisms irradiated by
  non-thermal microwaves

abstract:
  Pennes' differential equation for bioheat transfer and the heat transfer
equation are solved for the temperature distribution in a living tissue with
spherical inclusions, irradiated by microwave power. It is shown that relative
temperature excess in a small inclusion in the tissue in some cases is
inversely proportional to its radius and does not depend on the applied power.
In pulsing RF fields the effect is amplified proportionally to the ratio of the
pulse period to the pulse duration. The local temperature rise significantly
outpaces the averaged one and therefore the Watt to Weight SAR limits may be
insufficient to estimate the safety of RF radiation and the conventional
division of the biological effects of electromagnetic fields on the thermal and
non-thermal needs to be revised.


title: A test for stationarity based on empirical processes

abstract:
  In this paper we investigate the problem of testing the assumption of
stationarity in locally stationary processes. The test is based on an estimate
of a Kolmogorov-Smirnov type distance between the true time varying spectral
density and its best approximation through a stationary spectral density.
Convergence of a time varying empirical spectral process indexed by a class of
certain functions is proved, and furthermore the consistency of a bootstrap
procedure is shown which is used to approximate the limiting distribution of
the test statistic. Compared to other methods proposed in the literature for
the problem of testing for stationarity the new approach has at least two
advantages: On one hand, the test can detect local alternatives converging to
the null hypothesis at any rate $g_T\to0$ such that $g_TT^{1/2}\to \infty$,
where $T$ denotes the sample size. On the other hand, the estimator is based on
only one regularization parameter while most alternative procedures require
two. Finite sample properties of the method are investigated by means of a
simulation study, and a comparison with several other tests is provided which
have been proposed in the literature.


title: Quasi-quantized Disk Structure around Rotating Neutron Stars

abstract:
  In accreting neutron star (NS) low-mass X-ray binary (LMXB) systems, NS
accretes material from its low-mass companion via a Keplerian disk. In a
viscous accretion disk, inflows orbit the NS and spiral in due to dissipative
processes, such as the viscous process and collisions of elements. The dynamics
of accretion flows in the inner region of an accretion disk is significantly
affected by the rotation of NS. The rotation makes NS, thus the space-time
metric, deviate from the originally spherical symmetry, and leads to
gravitational quadrupole, on one hand. On the other hand, a rotating NS drags
the local inertial frame in its vicinity, which is known as the rotational
frame-dragging effect. In this paper, {\bf we investigate the orbital motion of
accretion flows of accreting NS/LMXBs and demonstrate that the rotational
effects of NS result in a band of quasi-quantized structure in the inner region
of the accretion disk, which is different, in nature, from the scenario in the
strong gravity of black hole arising from the resonance for frequencies related
to epicyclic and orbital motions. We also demonstrate that such a disk
structure may account for frequencies seen in X-ray variability, such as
quasi-periodic oscillations, and can be a potential promising tool of
investigation for photon polarization.


title: Enumeration of irreducible contact graphs on the sphere

abstract:
  In this article, using the computer, are enumerated all locally-rigid
packings by $N$ congruent circles (spherical caps) on the unit sphere ${\Bbb
S}^2 $ with $N < 12.$ This is equivalent to the enumeration of irreducible
spherical contact graphs.


title: On the perturbations on satellites probing General Relativity

abstract:
  Non-gravitational Yarkovsky-Rubincam effect for LAGEOS and LAGEOS 2
satellites used to probe General Relativity has been revealed by means of the
Kolmogorov analysis of their perturbations. We present the method and its
efficiency at modeling of generated systems with properties expected at the
satellite laser ranging measurements and then at satellite residual data
analysis.


title:
Observation and measurement of an extra phase shift created by optically
  detuned light storage in metastable helium

abstract:
  Electromagnetically induced transparency (EIT) in metastable helium at room
temperature is experimentally shown to exhibit light storage capabilities for
intermediate values of the detuning between the coupling and probe beams and
the center of the atomic Doppler profiles. An additional phase shift is shown
to be imposed to the retrieved pulse of light when the EIT protocol is
performed at non-zero optical detunings. The value of this phase shift is
measured for different optical detunings between 0 and 2 GHz, and its origin is
discussed.


title: The Monge-Kantorovich problem for distributions and applications

abstract:
  We study the Kantorovich-Rubinstein transhipment problem when the difference
between the source and the target is not anymore a balanced measure but belongs
to a suitable subspace $X(\Omega)$ of first order distribution. A particular
subclass $X_0^\sharp(\Omega)$ of such distributions will be considered which
includes the infinite sums of dipoles $\sum_k(\delta_{p_k}-\delta_{n_k})$
studied in \cite{P1, P2}. In spite of this weakened regularity, it is shown
that an optimal transport density still exists among nonnegative finite
measures. Some geometric properties of the Banach spaces $X(\Omega)$ and
$X_0^\sharp(\Omega)$ can be then deduced.


title: Pseudo-Riemannian geometry in terms of multi-linear brackets

abstract:
  We show that the pseudo-Riemannian geometry of submanifolds can be formulated
in terms of higher order multi-linear maps. In particular, we obtain a Poisson
bracket formulation of almost (para-)K\"ahler geometry.


title: IR-stimulated visible fluorescence in pink and brown diamond

abstract:
  Irradiation of natural pink and brown diamond by middle-ultraviolet light
(photon energy > 4.1 eV) is seen to induce anomalous fluorescence phenomena at
N3 defect centres (structure N3-V). When diamonds primed in this fashion are
subsequently exposed to infrared light (even with a delay of many hours), a
transient burst of blue N3 fluorescence is observed. The dependence of this
IR-triggered fluorescence on pump wavelength and intensity suggest that this
fluorescence phenomena is intrinsically related to pink diamond photochromism.
An energy transfer process between N3 defects and other defect species can
account for both the UV-induced fluorescence intensity changes, and the
apparent optical upconversion of IR light. From this standpoint, we consider
the implications of this N3 fluorescence behaviour for the current
understanding of pink diamond photochromism kinetics.


title:
QCD radiative corrections to the soft spectator contribution in the wide
  angle Compton scattering

abstract:
  We derive the complete factorization formula for the leading power
contribution in wide angle Compton scattering. It consists of the soft- and
hard-spectator contributions. The hard-spectator contribution is well known and
defined in the form of the convolution of a hard kernel with the nucleon
distribution amplitudes. The soft-spectator contribution describes the
scattering which involves the soft modes. We use the soft collinear effective
theory in order to define this term in a field theoretical approach. Using the
SCET framework we provide the proof of the factorization formula. We also
compute the next-to-leading QCD corrections to the hard coefficient function of
the soft spectator contribution and perform a phenomenological analysis of
existing experimental data within the developed formalism.


title:
Codebook based Audio Feature Representation for Music Information
  Retrieval

abstract:
  Digital music has become prolific in the web in recent decades. Automated
recommendation systems are essential for users to discover music they love and
for artists to reach appropriate audience. When manual annotations and user
preference data is lacking (e.g. for new artists) these systems must rely on
\emph{content based} methods. Besides powerful machine learning tools for
classification and retrieval, a key component for successful recommendation is
the \emph{audio content representation}.
  Good representations should capture informative musical patterns in the audio
signal of songs. These representations should be concise, to enable efficient
(low storage, easy indexing, fast search) management of huge music
repositories, and should also be easy and fast to compute, to enable real-time
interaction with a user supplying new songs to the system.
  Before designing new audio features, we explore the usage of traditional
local features, while adding a stage of encoding with a pre-computed
\emph{codebook} and a stage of pooling to get compact vectorial
representations. We experiment with different encoding methods, namely
\emph{the LASSO}, \emph{vector quantization (VQ)} and \emph{cosine similarity
(CS)}. We evaluate the representations' quality in two music information
retrieval applications: query-by-tag and query-by-example. Our results show
that concise representations can be used for successful performance in both
applications. We recommend using top-$\tau$ VQ encoding, which consistently
performs well in both applications, and requires much less computation time
than the LASSO.


title:
Full information maximum likelihood estimation in factor analysis with a
  lot of missing values

abstract:
  We consider the problem of full information maximum likelihood (FIML)
estimation in a factor analysis model when a majority of the data values are
missing. The expectation-maximization (EM) algorithm is often used to find the
FIML estimates, in which the missing values on observed variables are included
in complete data. However, the EM algorithm has an extremely high computational
cost when the number of observations is large and/or plenty of missing values
are involved. In this paper, we propose a new algorithm that is based on the EM
algorithm but that efficiently computes the FIML estimates. A significant
improvement in the computational speed is realized by not treating the missing
values on observed variables as a part of complete data. Our algorithm is
applied to a real data set collected from a Web questionnaire that asks about
first impressions of human; almost $90\%$ of the data values are missing. When
there are many missing data values, it is not clear if the FIML procedure can
achieve good estimation accuracy even if the number of observations is large.
In order to investigate this, we conduct Monte Carlo simulations under a wide
variety of sample sizes.


title:
Algebro-geometric aspects of superintegrability: the degenerate Neumann
  system

abstract:
  In this article we use algebro-geometric tools to describe the structure of a
superintegrable system. We study degenerate Neumann system with potential
matrix that has some eigenvalues of multiplicity greater than one. We show that
the degenerate Neumann system is superintegrable if and only if its spectral
curve is reducible and that its flow can be linearized on the generalized
Jacobians of the spectral curve. We also show that the generalized Jacobians of
the hypereliptic component of the spectral curves are models for the minimal
invariant tori of the flow. Moreover the spectral invariants generate local
actions that span the invariant tori, while the moment maps for the rotational
symmetries provide additional first integrals of the system. Using our results
we reproduce already known facts that the degenerate Neumann system is
superintegrable, if its potencial matrix has eigenvalues of multiplicity
greater or equal than $3$.


title:
Structural and optical properties of self-catalytic GaAs:Mn nanowires
  grown by molecular beam epitaxy on silicon substrates

abstract:
  Mn-doped GaAs nanowires were grown in the self-catalytic growth mode on
oxidized Si(100) surface by molecular beam epitaxy and characterized by
scanning and transmission electron microscopy, Raman scattering,
photoluminescence, cathodoluminescence, and electron transport measurements.
The transmission electron microscopy studies evidenced the substantial
accumulation of Mn inside the catalyzing Ga droplets at the top of the
nanowires. Optical and transport measurements revealed that the limit of Mn
content for self-catalysed growth of GaAs nanowires corresponds to the doping
level, i.e., is much lower than the Mn/Ga flux ratio (about 3%) used during the
MBE growth. The resistivity measurements of individual nanowires confirmed that
they are conductive, in accordance with the photoluminescence measurements
which showed the presence of Mn2+ acceptors located at Ga sites of the GaAs
host lattice of the nanowires. An anomalous temperature dependence of the
photoluminescence related to excitons was demonstrated for Mn-doped GaAs
nanowires.


title: Solitons in gauge theories: existence and dependence on the charge

abstract:
  In this paper we review recent results on the existence of non-topological
solitons in classical relativistic nonlinear field theories. We follow the
Coleman approach, which is based on the existence of two conservation laws,
energy and charge. In particular we show that under mild assumptions on the
nonlinear term it is possible to prove the existence of solitons for a set of
admissible charges. This set has been studied for the nonlinear Klein-Gordon
equation, and in this paper we state new results in this direction for the
Klein-Gordon-Maxwell system.


title: Towards a realistic population of simulated galaxy groups and clusters

abstract:
  We present a new suite of large-volume cosmological hydrodynamical
simulations called cosmo-OWLS. They form an extension to the OverWhelmingly
Large Simulations (OWLS) project, and have been designed to help improve our
understanding of cluster astrophysics and non-linear structure formation, which
are now the limiting systematic errors when using clusters as cosmological
probes. Starting from identical initial conditions in either the Planck or
WMAP7 cosmologies, we systematically vary the most important `sub-grid'
physics, including feedback from supernovae and active galactic nuclei (AGN).
We compare the properties of the simulated galaxy groups and clusters to a wide
range of observational data, such as X-ray luminosity and temperature, gas mass
fractions, entropy and density profiles, Sunyaev-Zel'dovich flux, I-band
mass-to-light ratio, dominance of the brightest cluster galaxy, and central
massive black hole (BH) masses, by producing synthetic observations and
mimicking observational analysis techniques. These comparisons demonstrate that
some AGN feedback models can produce a realistic population of galaxy groups
and clusters, broadly reproducing both the median trend and, for the first
time, the scatter in physical properties over approximately two decades in mass
($10^{13} \lesssim M_{500} \lesssim 10^{15}~\textrm{M}_{\odot}$) and 1.5
decades in radius ($0.05 \lesssim r/r_{500} \lesssim 1.5$). However, in other
models, the AGN feedback is too violent (even though they reproduce the
observed BH scaling relations), implying calibration of the models is required.
The production of realistic populations of simulated groups and clusters, as
well as models that bracket the observations, opens the door to the creation of
synthetic surveys for assisting the astrophysical and cosmological
interpretation of cluster surveys, as well as quantifying the impact of
selection effects.


title:
Long time dynamics of highly concentrated solitary waves for the
  nonlinear Schroedinger equation

abstract:
  In this paper we study the behavior of solutions of a nonlinear Schroedinger
equation in presence of an external potential, which is allowed to be singular
at one point. We show that the solution behaves like a solitary wave for long
time even if we start from a unstable solitary wave, and its dynamics coincide
with that of a classical particle evolving according to a natural effective
Hamiltonian.


title: On Dynamics of G-Band Bright Points

abstract:
  Various parameters describing the dynamics of G-band bright points (GBPs)
were derived from G-band images, acquired by the Dutch Open Telescope (DOT), of
a quiet region close to the disk center. Our study is based on four commonly
used diagnostics (effective velocity, change in the effective velocity, change
in the direction angle, and centrifugal acceleration) and two new ones (rate of
motion and time lag between recurrence of GBPs). The results concerning the
commonly used parameters are in agreement with previous studies for a
comparable spatial and temporal resolution of the used data.To broaden our
understanding of the dynamics of GBPs, two new parameters were defined: the
real displacement between their appearance and disappearance (rate of motion)
and the frequency of their recurrence at the same locations (time lag). Results
for both new parameters indicate that the locations of different dynamical
types of GBPs (stable/farther traveling or with short/long lifetimes) are bound
to the locations of more stable and long-living magnetic field concentrations.
Thus, the disappearance/reappearance of the tracked GBPs cannot be perceived as
the disappearance/reappearance of their corresponding magnetic field
concentrations.


title:
Learning rates of $l^q$ coefficient regularization learning with
  Gaussian kernel

abstract:
  Regularization is a well recognized powerful strategy to improve the
performance of a learning machine and $l^q$ regularization schemes with
$0<q<\infty$ are central in use. It is known that different $q$ leads to
different properties of the deduced estimators, say, $l^2$ regularization leads
to smooth estimators while $l^1$ regularization leads to sparse estimators.
Then, how does the generalization capabilities of $l^q$ regularization learning
vary with $q$? In this paper, we study this problem in the framework of
statistical learning theory and show that implementing $l^q$ coefficient
regularization schemes in the sample dependent hypothesis space associated with
Gaussian kernel can attain the same almost optimal learning rates for all
$0<q<\infty$. That is, the upper and lower bounds of learning rates for $l^q$
regularization learning are asymptotically identical for all $0<q<\infty$. Our
finding tentatively reveals that, in some modeling contexts, the choice of $q$
might not have a strong impact with respect to the generalization capability.
From this perspective, $q$ can be arbitrarily specified, or specified merely by
other no generalization criteria like smoothness, computational complexity,
sparsity, etc..


title: Nielsen zeta functions on infra-nilmanifolds up to dimension three

abstract:
  In this paper, we will list all possible self-maps on infra-nilmanifolds up
to dimension three and we will give the Nielsen zeta function for any of those
maps.


title:
Semiclassical stationary states for nonlinear Schr\"odinger equations
  under a strong external magnetic field

abstract:
  We construct solutions to the nonlinear magnetic Schr\"odinger equation $$
  \left\{ \begin{aligned}
  - \varepsilon^2 \Delta_{A/\varepsilon^2} u + V u &= \lvert u\rvert^{p-2} u &
&\text{in}\ \Omega,\\ u &= 0 & &\text{on}\ \partial\Omega,
  \end{aligned}
  \right. $$ in the semiclassical r\'egime with strong magnetic fields. In
contrast with the well-studied mild magnetic field r\'egime, the limiting
energy depends on the magnetic field allowing to recover the Lorentz force in
the semi-classical limit. Our solutions concentrate around global or local
minima of a limiting energy that depends on the electric potential and the
magnetic field. The results cover unbounded domains, fast-decaying electric
potential and unbounded electromagnetic fields. The construction is variational
and is based on an asymptotic analysis of solutions to a penalized problem in
the spirit of M. del Pino and P. Felmer.


title:
Seven competing ways to recover the Michaelis-Menten equation reveal the
  alternative approaches to steady state modeling

abstract:
  The Michaelis-Menten enzymatic reaction is sufficient to perceive many
subtleties of network modeling, including the concentration and time scales
separations, the formal equivalence between bulk phase and single-molecule
approaches, or the relationships between single-cycle transient probabilities
and steady state rates. Seven methods proposed by different authors and
yielding the same famous Michaelis-Menten equation, are selected here to
illustrate the kinetic and probabilistic use of rate constants and to review
basic techniques for handling them. Finally, the general rate of an ordered
multistep reaction, of which the Michaelis-Menten reaction is a particular
case, is deduced from a Markovian approach.


title: Network Traffic Analysis:Hadoop Pig vs Typical MapReduce

abstract:
  Big data analysis has become much popular in the present day scenario and the
manipulation of big data has gained the keen attention of researchers in the
field of data analytics. Analysis of big data is currently considered as an
integral part of many computational and statistical departments. As a result,
novel approaches in data analysis are evolving on a daily basis. Thousands of
transaction requests are handled and processed everyday by different websites
associated with e-commerce, e-banking, e-shopping carts etc. The network
traffic and weblog analysis comes to play a crucial role in such situations
where Hadoop can be suggested as an efficient solution for processing the
Netflow data collected from switches as well as website access-logs during
fixed intervals.


title: On moduli spaces for quasi-tilted algebras

abstract:
  We prove that if a quasi-tilted algebra is tame, then the associated moduli
spaces are products of projective spaces. Together with an earlier result of
Chindris this gives a geometric characterization of the tame quasi-tilted
algebras.


title:
The PRL Stabilized High Resolution Echelle Fiber-fed Spectrograph:
  Instrument Description & First Radial Velocity Results

abstract:
  We present spectrograph design details and initial radial velocity results
from the PRL optical fiber-fed high-resolution cross-dispersed echelle
spectrograph (PARAS), which has recently been commissioned at the Mt Abu 1.2 m
telescope, in India. Data obtained as part of the post-commissioning tests with
PARAS show velocity precision better than 2m/s over a period of several months
on bright RV standard stars. For observations of sigma-Dra we report 1.7m/s
precision for a period of seven months and 2.1m/s for HD 9407 over a period of
2 months. PARAS is capable of a single-shot spectral coverage of 3800A - 9500A
at a resolution of about 67,000. The RV results were obtained between 3800A and
6900A using simultaneous wavelength calibration with a Thorium-Argon (ThAr)
hollow cathode lamp. The spectrograph is maintained under stable conditions of
temperature with a precision of 0.01 - 0.02C (rms) at 25.55C, and enclosed in a
vacuum vessel at pressure of 0.1 +/-0.03 mbar. The blaze peak efficiency of the
spectrograph between 5000A and 6500A, including the detector, is 30%; and about
25% with the fiber transmission. The total efficiency, including spectrograph,
fiber transmission, focal ratio degradation (FRD), and telescope (with 81%
reflectivity) is about 7% in the same wavelength region on a clear night with
good seeing conditions.


title: On multi-index filtrations associated to Weierstrass semigroups

abstract:
  The aim of this paper is to review the main techniques in the computation of
Weierstra\ss semigroup at several points of curves defined over perfect fields,
with special emphasis on the case of two points. Some hints about the usage of
some packages of the computer algebra software \textsc{Singular} are also
given.


title:
Harnack inequalities on weighted graphs and some applications to the
  random conductance model

abstract:
  We establish elliptic and parabolic Harnack inequalities on graphs with
unbounded weights. As an application we prove a local limit theorem for a
continuous time random walk $X$ in an environment of ergodic random
conductances taking values in $[0, \infty)$ satisfying some moment conditions.


title: On the normality of Higgins commutators

abstract:
  In a semi-abelian context, we study the condition (NH) asking that Higgins
commutators of normal subobjects are normal subobjects. We provide examples of
categories that do or do not satisfy this property. We focus on the
relationship with the "Smith is Huq" condition (SH) and characterise those
semi-abelian categories in which both (NH) and (SH) hold in terms of reflection
and preservation properties of the change of base functors of the fibration of
points.


title:
Charge-density-wave states in double-layer graphene structures in a high
  magnetic field

abstract:
  We study the phases of correlated charge-density waves that form at a high
magnetic field in two parallel graphene flakes separated by a thin insulator.
The predicted phases include the square and hexagonal charge-density-wave
bubbles, and a quasi-one-dimensional stripe phase. We find that the transition
temperature for such phases is within the experimentally accessible range and
that formation of interlayer-correlated states produces a negative
compressibility contribution to the differential capacitance of this system.


title: The global existence of Yang-Mills fields on curved space-times

abstract:
  This is an introductory chapter in a series in which we take a systematic
study of the Yang-Mills equations on curved space-times. In this first, we
provide standard material that consists in writing the proof of the global
existence of Yang-Mills fields on arbitrary curved space-times using the
Klainerman-Rodnianski parametrix combined with suitable Gr\"onwall type
inequalities. While the Chru\'sciel-Shatah argument requires a simultaneous
control of the $L^{\infty}_{loc}$ and the $H^{2}_{loc}$ norms of the Yang-Mills
curvature, we can get away by controlling only the $H^{1}_{loc}$ norm instead,
and write a new gauge independent proof on arbitrary, fixed, sufficiently
smooth, globally hyperbolic, curved 4-dimensional Lorentzian manifolds. This
manuscript is written in an expository way in order to provide notes to
Master's level students willing to learn mathematical General Relativity.


title: M-theory Solutions Invariant under $D(2,1;\gamma) \oplus D(2,1;\gamma)$

abstract:
  We simplify and extend the construction of half-BPS solutions to
11-dimensional supergravity, with isometry superalgebra D(2,1;\gamma) \oplus
D(2,1;\gamma). Their space-time has the form AdS_3 x S^3 x S^3 warped over a
Riemann surface \Sigma. It describes near-horizon geometries of M2 branes
ending on, or intersecting with, M5 branes along a common string. The general
solution to the BPS equations is specified by a reduced set of data (\gamma, h,
G), where \gamma is the real parameter of the isometry superalgebra, and h and
G are functions on \Sigma whose differential equations and regularity
conditions depend only on the sign of \gamma. The magnitude of \gamma enters
only through the map of h, G onto the supergravity fields, thereby promoting
all solutions into families parametrized by |\gamma|. By analyzing the
regularity conditions for the supergravity fields, we prove two general
theorems: (i) that the only solution with a 2-dimensional CFT dual is AdS_3 x
S^3 x S^3 x R^2, modulo discrete identifications of the flat R^2, and (ii) that
solutions with \gamma < 0 cannot have more than one asymptotic
higher-dimensional AdS region. We classify the allowed singularities of h and G
near the boundary of \Sigma, and identify four local solutions: asymptotic
AdS_4/Z_2 or AdS_7' regions; highly-curved M5-branes; and a coordinate
singularity called the "cap". By putting these "Lego" pieces together we
recover all known global regular solutions with the above symmetry, including
the self-dual strings on M5 for $\gamma < 0$, and the Janus solution for \gamma
> 0, but now promoted to families parametrized by |\gamma|. We also construct
exactly new regular solutions which are asymptotic to AdS_4/Z_2 for \gamma < 0,
and conjecture that they are a different superconformal limit of the self-dual
string.


title:
Searching for gravitational waves from known pulsars at once and twice
  the spin frequency

abstract:
  The existence of a superfluid core in the interior of a rotating neutron star
may have an influence on its gravitational wave emission. In addition to the
usually-assumed pure quadrupole radiation with the gravitational wave frequency
at twice the spin frequency, a frequency of rotation itself may also be present
in the gravitational wave spectrum. We study the parameters of a general model
for such emission, compare it with previously proposed, simpler models, discuss
the feasibility of the recovery of the stellar parameters and carry out the
Monte Carlo simulations to test the performance of our estimation method.


title: Sparse similarity-preserving hashing

abstract:
  In recent years, a lot of attention has been devoted to efficient nearest
neighbor search by means of similarity-preserving hashing. One of the plights
of existing hashing techniques is the intrinsic trade-off between performance
and computational complexity: while longer hash codes allow for lower false
positive rates, it is very difficult to increase the embedding dimensionality
without incurring in very high false negatives rates or prohibiting
computational costs. In this paper, we propose a way to overcome this
limitation by enforcing the hash codes to be sparse. Sparse high-dimensional
codes enjoy from the low false positive rates typical of long hashes, while
keeping the false negative rates similar to those of a shorter dense hashing
scheme with equal number of degrees of freedom. We use a tailored feed-forward
neural network for the hashing function. Extensive experimental evaluation
involving visual and multi-modal data shows the benefits of the proposed
method.


title: Dial It In: Rotating RF Sensors to Enhance Radio Tomography

abstract:
  A radio tomographic imaging (RTI) system uses the received signal strength
(RSS) measured by RF sensors in a static wireless network to localize people in
the deployment area, without having them to carry or wear an electronic device.
This paper addresses the fact that small-scale changes in the position and
orientation of the antenna of each RF sensor can dramatically affect imaging
and localization performance of an RTI system. However, the best placement for
a sensor is unknown at the time of deployment. Improving performance in a
deployed RTI system requires the deployer to iteratively "guess-and-retest",
i.e., pick a sensor to move and then re-run a calibration experiment to
determine if the localization performance had improved or degraded. We present
an RTI system of servo-nodes, RF sensors equipped with servo motors which
autonomously "dial it in", i.e., change position and orientation to optimize
the RSS on links of the network. By doing so, the localization accuracy of the
RTI system is quickly improved, without requiring any calibration experiment
from the deployer. Experiments conducted in three indoor environments
demonstrate that the servo-nodes system reduces localization error on average
by 32% compared to a standard RTI system composed of static RF sensors.


title:
Students' Perceptions and Attitude towards the effectiveness of Prezi
  Uses in learning Islamic Subject

abstract:
  Prezi is a Hungarian software company, producing a cloud-based presentation
software and storytelling tool for presenting ideas on a virtual canvas
(Prezi.com). Prezi is one of the teaching materials that help students in
learning process. This study aims to explore the effectiveness of using Prezi
in Islamic education subject among secondary schools under the topic of
marriage in Islam: polygamy. Specifically its aims to identify students
interest and second examine their attitude towards the uses of Prezi in
learning Islamic educations. A total of 22 students participated in the survey,
employing a 22-item questionnaire. The data was analyzed quantitatively using
Statistical Package for the Social Sciences (SPSS). Result from this study
revealed that student shows their interest in learning Islamic Educations when
teachers uses Prezi. In additions students also show positive attitude towards
uses of Prezi in Classroom. As conclusions, the uses of Prezi presentation is
easy and its technique for developing a more creative and innovative approach
in teaching strategies among Islamic educators.


title: How (non-) linear is the hydrodynamics of heavy ion collisions?

abstract:
  We provide evidence from full numerical solutions that the hydrodynamical
evolution of initial density fluctuations in heavy ion collisions can be
understood order-by-order in a perturbative series in deviations from a smooth
and azimuthally symmetric background solution. To leading linear order, modes
with different azimuthal wave numbers do not mix. Quadratic and higher order
corrections are small and can be understood as overtones with corresponding
wave numbers.


title: Love Games: A Game Theory Approach to Compatibility

abstract:
  In this note, we present a compatibility test based on John Nash's
game-theoretic notion of equilibrium strategy. The test must be taken
separately by both partners, making it difficult for either partner alone to
control the outcome. The mathematics behind the test including Nash's
celebrated theorem and an example from the film, "A Beautiful Mind," are
discussed as well as how to customize the test for more accurate results and
how to modify the test to evaluate interpersonal relationships in other
settings, not only romantic. To investigate the long-term dynamics of give and
take in a relationship we introduce the "iterated dating dilemma" and apply the
notion of "zero-determinant payoff strategy" introduced by Dyson and Press in
2012 for the iterated prisoner's dilemma.


title: Chiral Dirac-Born-Infeld solitons with SDiff symmetry

abstract:
  We propose a new DBI extension of a Skyrme type model which allows for BPS
topological solitons with arbitrary value of the baryon charge. The model is
built out of the baryon density squared and in the limit of small fields tends
to the BPS Skyrme model. We consider some generalizations to higher dimension
and other K-deformed actions.


title: N-Point Tree-Level Scattering Amplitude in the New Berkovits' String

abstract:
  We give a proof by direct computation that at tree level, the twistor-like
superstring theory in the pure spinor formalism proposed very recently by
Berkovits describes ten-dimensional N=1 super Yang-Mills in its heterotic
version, and type II supergravity in its type II version. The Yang-Mills case
agrees with the result obtained by Mafra, Schlotterer, Stieberger and Tsimpis.
When restricting to gluon and graviton scattering, this new theory gives rise
to Cachazo-He-Yuan formula.


title:
Molecular communication networks with general molecular circuit
  receivers

abstract:
  In a molecular communication network, transmitters may encode information in
concentration or frequency of signalling molecules. When the signalling
molecules reach the receivers, they react, via a set of chemical reactions or a
molecular circuit, to produce output molecules. The counts of output molecules
over time is the output signal of the receiver. The aim of this paper is to
investigate the impact of different reaction types on the information
transmission capacity of molecular communication networks. We realise this aim
by using a general molecular circuit model. We derive general expressions of
mean receiver output, and signal and noise spectra. We use these expressions to
investigate the information transmission capacities of a number of molecular
circuits.


title: Projective modules of $0$-Schur algebras

abstract:
  We study the structure of the $0$-Schur algebra $S_0(n, r)$ following the
geometric construction of $S_0(n, r)$ by Jensen and Su \cite{JS}. The main
results are the construction and classification of indecomposable projective
modules. In addition, we construct bases of these modules and their
homomorphism spaces. We also give a filtration of projective modules, which
leads to a decomposition of $S_0(n,r)$ into indecomposable left modules.


title:
Accurate semiclassical spectral asymptotics for a two-dimensional
  magnetic Schr\"odinger operator

abstract:
  We revisit the problem of semiclassical spectral asymptotics for a pure
magnetic Schr\"odinger operator on a two-dimensional Riemannian manifold. We
suppose that the minimal value $b_0$ of the intensity of the magnetic field is
strictly positive, and the corresponding minimum is unique and non-degenerate.
The purpose is to get the control on the spectrum in an interval $(hb_0, h(b_0
+\gamma_0)]$ for some $\gamma_0>0$ independent of the semiclassical parameter
$h$. The previous papers by Helffer-Mohamed and by Helffer-Kordyukov were only
treating the ground-state energy or a finite (independent of $h$) number of
eigenvalues. Note also that N. Raymond and S. Vu Ngoc have recently developed a
different approach of the same problem.


title:
Rotating and Moving D-Branes in the Presence of Various Background
  Fields

abstract:
  We calculate the bosonic boundary state associated with a rotating and moving
D$p$-brane in the presence of the antisymmetric tensor field, a $U(1)$ gauge
field and a tachyon field. Rotation and motion are in the brane volume. We
reconstruct this boundary state via the group $PSL(2,R)$ to be applicable when
the tachyon field is presented. This modified boundary state enables us to
calculate the interaction amplitude between two parallel D$p$-branes with
rotation and motion. The long-range force of this interaction will be obtained.
The boundary state also enables us to investigate the tachyon condensation on a
rotating and moving D$p$-brane.


title: Large Scale Structure Observations

abstract:
  Galaxy Surveys are enjoying a renaissance thanks to the advent of
multi-object spectrographs on ground-based telescopes. The last 15 years have
seen the fruits of this experimental advance, including the 2-degree Field
Galaxy Redshift Survey (2dFGRS; Colless et al. 2003) and the Sloan Digital Sky
Survey (SDSS; York et al. 2000). Most recently, the Baryon Oscillation
Spectroscopic Survey (BOSS; Dawson et al. 2013), part of the SDSS-III project
(Eisenstein et al. 2011), has provided the largest volume of the low-redshift
Universe ever surveyed with a galaxy density useful for high-precision
cosmology. This set of lecture notes looks at some of the physical processes
that underpin these measurements, the evolution of measurements themselves, and
looks ahead to the next 15 years and the advent of surveys such as the enhanced
Baryon Oscillation Spectroscopic Survey (eBOSS), the Dark Energy Spectroscopic
Instrument (DESI) and the ESA Euclid satellite mission.


title:
Weak solutions to the complex Monge-Amp\`ere equation on Hermitian
  manifolds

abstract:
  The main result asserts the existence of continuous solutions of the complex
Monge-Amp\`ere equation with the right hand side in $L^p, p>1$, on compact
Hermitian manifolds.


title:
Stochasticity in Ca$^{2+}$ increase in spines enables robust and
  sensitive information coding

abstract:
  A dendritic spine is a very small structure (~0.1 {\mu}m$^3$) of a neuron
that processes input timing information. Why are spines so small? Here, we
provide functional reasons; the size of spines is optimal for information
coding. Spines code input timing information by the probability of Ca$^{2+}$
increases, which makes robust and sensitive information coding possible. We
created a stochastic simulation model of input timing-dependent Ca$^{2+}$
increases in a cerebellar Purkinje cell's spine. Spines used probability coding
of Ca$^{2+}$ increases rather than amplitude coding for input timing detection
via stochastic facilitation by utilizing the small number of molecules in a
spine volume, where information per volume appeared optimal. Probability coding
of Ca$^{2+}$ increases in a spine volume was more robust against input
fluctuation and more sensitive to input numbers than amplitude coding of
Ca$^{2+}$ increases in a cell volume. Thus, stochasticity is a strategy by
which neurons robustly and sensitively code information.


title:
Global analysis of generalized parton distributions -- collider
  kinematics --

abstract:
  We utilize H1 and ZEUS data for exclusive electroproduction of photons,
$\rho^0$- and $\phi$-mesons to access generalized parton distributions at small
momentum fraction. To do so, we employ state-of-the art techniques, based on
next-to-leading order perturbation theory, flexible model parametrization, and
Bayesian inference. We provide a partonic interpretation of our analysis, where
emphasize is given to the transverse distribution of sea quarks and gluons.


title:
Nonlocal Operators and Duality in Abelian Gauge Theory on a
  Four-Manifold

abstract:
  We generalize our picture in [arXiv:0904.1744], and consider a pure abelian
gauge theory on a four-manifold with nonlocal operators of every codimension
arbitrarily and simultaneously inserted. We explicitly show that (i) the theory
enjoys exact S-duality for certain choices of operator parameters; (ii) if
there are only trivially-embedded surface operators and Wilson loop operators,
or if there are only Wilson-'t Hooft loop operators, the theory enjoys a more
general and exact SL(2,Z) or \Gamma_0(2) duality; (iii) the parameters of the
loop and surface operators transform like electric-magnetic charges under the
SL(2,Z) or \Gamma_0(2) duality of the theory. Through the formalism of duality
walls, we derive the transformation of loop and surface operators embedded in a
Chern-Simons operator. Via a Hamiltonian perspective, we furnish an alternative
understanding of the SL(2,Z) duality. Last but not least, we also compute the
partition function and correlation function of gauge-invariant local operators,
and find that they transform as generalized modular forms under the respective
duality groups.


title: Gluon condensates from the Hamiltonian formalism

abstract:
  We derive recently obtained relations, relating the logarithmic gauge
coupling derivative of the hadron mass and the cosmological constant to the
matter and vacuum gluon condensates, within a Hamiltonian framework. The key
idea is a canonical transformation which brings the relevant part of the
Hamiltonian into a suitable form. Furthermore we illustrate the relations
within the Schwinger model and ${\cal N}=2$ super Yang Mills theory
(Seiberg-Witten theory).


title: On idiosyncratic stochasticity of financial leverage effects

abstract:
  We model leverage as stochastic but independent of return shocks and of
volatility and perform likelihood-based inference via the recently developed
iterated filtering algorithm using S&P500 data, contributing new evidence to
the still slim empirical support for random leverage variation.


title:
The initial stages of heavy-ion collisions in the Color Glass Condensate
  framework

abstract:
  In this short review, we present the description of the early stages of a
heavy ion collision at high energy in the Color Glass Condensate framework.


abstract:
  Electron assisted neutron exchange process in solid state environment is
investigated. It is shown that if a metal is irradiated with free electrons
then the $e+$ $_{Z}^{A_{1}}X+$ $_{Z}^{A_{2}}X\rightarrow e^{\prime }+$
$%_{Z}^{A_{1}-1}X+$ $_{Z}^{A_{2}+1}X+\Delta $ electron assisted neutron
exchange process has measurable probability even in the case of slow electrons
of energy much less than the reaction energy $\Delta $. The transition
probability per unit time, the cross section of the process and the yield in an
irradiated sample are determined in the Weisskopf and long wavelength
approximations and in the single particle shell model. Numerical data for the
$e+$ $_{28}^{A_{1}}Ni+$ $_{28}^{A_{2}}Ni\rightarrow e^{\prime }+ $
$_{28}^{A_{1}+1}Ni+$ $_{28}^{A_{2}-1}Ni+\Delta $ and the $e+$
$%_{46}^{A_{1}}Pd+$ $_{46}^{A_{2}}Pd\rightarrow e^{\prime }+$
$%_{46}^{A_{1}+1}Pd+$ $_{46}^{A_{2}-1}Pd+\Delta $ electron assisted neutron
exchange reactions are also presented.


title: Simple sl_{n+1}-module structures on U(h)

abstract:
  We study the category M consisting of U(sl_{n+1})-modules whose restriction
to U(h) is free of rank 1, in particular we classify isomorphism classes of
objects in M and determine their submodule structure. This leads to new
sl_{n+1}-modules. For n=1 we also find the central characters and derive an
explicit formula for taking tensor product with a simple finite dimensional
module.


title: On Vector Dominance

abstract:
  We argue that a Regge-pole modification of the VDM puts on equal footing the
asymptotic behaviour of electromagnetic and neutral vector meson currents.


title: The modular envelope of the cyclic operad Ass

abstract:
  We give a direct combinatorial proof that the modular envelope of the cyclic
operad Ass is the modular operad of (the homeomorphism classes of) 2D compact
surfaces with boundary with marked points.


title:
Complete permutation polynomials induced from complete permutations of
  subfields

abstract:
  We propose several techniques to construct complete permutation polynomials
of finite fields by virtue of complete permutations of subfields. In some
special cases, any complete permutation polynomials over a finite field can be
used to construct complete permutations of certain extension fields with these
techniques. The results generalize some recent work of several authors.


title:
Initial State Fluctuations and Final State Correlations in Relativistic
  Heavy-Ion Collisions

abstract:
  We review the phenomenology and theory of bulk observables in
ultra-relativistic heavy-ion collisions, focussing on recent developments
involving event-by-event fluctuations in the initial stages of a heavy ion
collision, and how they manifest in observed correlations. We first define the
relevant observables and show how each measurement is related to underlying
theoretical quantities. Then we review the prevailing picture of the various
stages of a collision, including the state-of-the-art modeling of the initial
stages of a collision and subsequent hydrodynamic evolution, as well as
hadronic scattering and freeze-out in the later stages. We then discuss the
recent results that have shaped our current understanding and identify the
challenges that remain. Finally, we point out open issues and the potential for
progress in the field.


title: Metastability for parabolic equations with drift: part 1

abstract:
  We provide a self-contained analysis, based entirely on pde methods, of the
exponentially long time behavior of solutions to linear uniformly parabolic
equations which are small perturbations of a transport equation with vector
field having a globally stable point. We show that the solutions converge to a
constant, which is either the initial value at the stable point or the boundary
value at the minimum of the associated quasi-potential. This work extends
previous results of Freidlin and Wentzell and Freidlin and Koralov and applies
also to semilinear elliptic pde.


title: Optimal Combinatorial Batch Codes based on Block Designs

abstract:
  Batch codes, introduced by Ishai, Kushilevitz, Ostrovsky and Sahai, represent
the distributed storage of an $n$-element data set on $m$ servers in such a way
that any batch of $k$ data items can be retrieved by reading at most one (or
more generally, $t$) items from each server, while keeping the total storage
over $m$ servers equal to $N$. This paper considers a class of batch codes (for
$t=1$), called combinatorial batch codes (CBC), where each server stores a
subset of a database. A CBC is called optimal if the total storage $N$ is
minimal for given $n,m$, and $k$. A $c$-uniform CBC is a combinatorial batch
code where each item is stored in exactly $c$ servers. A $c$-uniform CBC is
called optimal if its parameter $n$ has maximum value for given $m$ and $k$.
Optimal $c$-uniform CBCs have been known only for $c\in \{2,k-1,k-2\}$.
  In this paper we present new constructions of optimal CBCs in both the
uniform and general settings, for values of the parameters where tight bounds
have not been established previously. In the uniform setting, we provide
constructions of two new families of optimal uniform codes with $c\sim
\sqrt{k}$. Our constructions are based on affine planes and transversal
designs.


title: Laboratory Investigation of Entrainment and Mixing in Oceanic Overflows

abstract:
  We present experimental measurements of a wall-bounded gravity current,
motivated by characterizing natural gravity currents such as oceanic overflows.
We use particle image velocimetry and planar laser-induced fluorescence to
simultaneously measure the velocity and density fields as they evolve
downstream of the initial injection from a turbulent channel flow onto a plane
inclined at 10$^\circ$ with respect to horizontal. The turbulence level of the
input flow is controlled by injecting velocity fluctuations upstream of the
output nozzle. The initial Reynolds number based on Taylor microscale of the
flow, R$_\lambda$, is varied between 40 and 120, and the effects of the initial
turbulence level are assessed. The bulk Richardson number $Ri$ for the flow is
about 0.3 whereas the gradient Richardson number $Ri_g$ varies between 0.04 and
0.25, indicating that shear dominates the stabilizing effect of stratification.
Kelvin-Helmholtz instability results in vigorous vertical transport of mass and
momentum. We present baseline characterization of standard turbulence
quantities and calculate, in several different ways, the fluid entrainment
coefficient $E$, a quantity of considerable interest in mixing parameterization
for ocean circulation models. We also determine properties of mixing as
represented by the flux Richardson number $Ri_f$ as a function of $Ri_g$ and
diapycnal mixing parameter $K_\rho$ versus buoyancy Reynolds number $Re_b$. We
find reasonable agreement with results from natural flows.


title: Energy Loss of High-Energy Particles in Particle-in-Cell Simulation

abstract:
  When a charged particle moves through a plasma at a speed much higher than
the thermal velocity of the plasma, it is subjected to the force of the
electrostatic field induced in the plasma by itself and loses its energy. This
process is well-known as the stopping power of a plasma. In this paper we show
that the same process works in particle-in-cell (PIC) simulations as well and
the energy loss rate of fast particles due to this process is mainly determined
by the number of plasma electrons contained in the electron skin depth volume.
However, since there are generally very few particles in that volume in PIC
simulations compared with real plasmas, the energy loss effect can be
exaggerated significantly and can affect the results. Therefore, especially for
the simulations that investigate the particle acceleration processes, the
number of particles used in the simulations should be chosen large enough to
avoid this artificial energy loss.


title:
Thermodynamics of Soft Wall Model in Einstein-Maxwell-Gauss-Bonnet
  Gravity

abstract:
  We investigate the thermodynamics of confnement/deconfinement transition in
soft wall model of QCD with Gauss-Bonnet corrections using AdS/CFT
correspondence. In bulk AdS space-time the transition is geometric and is known
as Hawking-Page transition. The Hawking-Page transition be- tween two
geometries, namely charged AdS black hole and thermally charged AdS have been
studied with Gauss-Bonnet corrections up-to first order. The Gauss-Bonnet
coupling modifies the transition temperature of the system, but qualitative
features remain unchanged. We obtain the curves between chemical potential and
transition temperature for different values of Gauss-Bonnet couplings. We find
that there exist a point in $\mu-T$ plane where lines with different value of
Gauss-Bonnet coupling cross each other. This point may be the onset of the
transition from first order to cross over behavior. The results are compared
with that of the hard wall model.


title: Completeness of the ring of polynomials

abstract:
  Let $k$ be an uncountable field. We prove that the polynomial ring
$R:=k[X_1,\dots,X_n]$ in $n\ge 2$ variables over $k$ is complete in its adic
topology. In addition we prove that also the localization $R_{\goth m}$ at a
maximal ideal $\goth m\subset R$ is adically complete. The first result settles
an old conjecture of C. U. Jensen, the second a conjecture of L. Gruson. Our
proofs are based on a result of Gruson stating (in two variables) that
$R_{\goth m}$ is adically complete when $R=k[X_1,X_2]$ and $\goth m=(X_1,X_2)$.


title: Holographic R\'enyi entropy for CFT with $W$ symmetry

abstract:
  In this paper we investigate the holographic R\'enyi entropy of two disjoint
intervals on complex plane with small cross ratio $x$ for conformal field
theory with $W$ symmetry in the ground state, which could be dual to a higher
spin AdS$_3$ gravity. We focus on the cases of $W_3$ and $W_4$ symmetries. In
order to see the nontrivial contributions from the $W$ fields, we calculate the
R\'enyi entropy in the expansion of $x$ to order $x^8$ in both the gravity and
the CFT sides. In the gravity side the classical contributions to the
entanglement entropy is still given by the Ryu-Takayanagi area formula under
the reasonable assumption, while the 1-loop quantum corrections have to take
into account of the contributions not only from massless gravitons, but also
from massless higher spin fields. In the CFT side we still use the operator
product expansion of twist operators in the small interval limit, but now we
need to consider the quasiprimary fields constructed from $W$ fields, besides
the ones from Virasoro Verma module. In the large central charge limit, we
obtain the classical, 1-loop, 2-loop, and 3-loop parts of the R\'enyi entropy.
The classical and 1-loop results in the gravity and the CFT sides are in exact
match. This confirms the higher spin gravity/CFT correspondence, and also
supports the holographic computation of R\'enyi entanglement entropy, including
the quantum correction, in both the AdS$_3$ gravity and the higher spin AdS$_3$
gravity.


title: Specific heat in two-dimensional melting

abstract:
  We report the specific heat $c_N$ around the melting transition(s) of
micrometer-sized superparamagnetic particles confined in two dimensions,
calculated from fluctuations of positions and internal energy, and
corresponding Monte Carlo simulations. Since colloidal systems provide single
particle resolution, they offer the unique possibility to compare the
experimental temperatures of peak position of $c_N(T)$ and symmetry breaking,
respectively. While order parameter correlation functions confirm the
Kosterlitz-Thouless-Halperin-Nelson-Young melting scenario where translational
and orientational order symmetries are broken at different temperatures with an
intermediate so called hexatic phase, we observe a single peak of the specific
heat within the hexatic phase, with excellent agreement between experiment and
simulation. Thus, the peak is not associated with broken symmetries but can be
explained with the total defect density, which correlates with the maximum
increase of isolated dislocations. The absence of a latent heat strongly
supports the continuous character of both transitions.


title:
An introduction to spherically symmetric loop quantum gravity black
  holes

abstract:
  We review recent developments in the treatment of spherically symmetric black
holes in loop quantum gravity. In particular, we discuss an exact solution to
the quantum constraints that represents a black hole and is free of
singularities. We show that new observables that are not present in the
classical theory arise in the quantum theory. We also discuss Hawking radiation
by considering the quantization of a scalar field on the quantum spacetime.


title:
Robust upper limit on the neutron single-particle energy of the
  $i_{13/2}$ orbit

abstract:
  The boundary of the neutron $i_{13/2}$ single-particle energy is investigated
with exact shell-model calculations, where random two-body interactions are
adopted to overcome the bias from effective interactions. Excitation energies
of $3^-_1$ state in $^{134}$Te and $^{136}$Xe, as well as those of $13/2^+_1$
states in $^{135}$Te and $^{137}$Xe, are taken as touchstones of our samplings.
A robust upper limit of $\varepsilon_{i13/2}<3.1$ MeV emerges in our
calculations, given the mixing of $i_{13/2}$ single-neutron configuration and
$f_{7/2}\otimes 3^-$ configuration in $13/2^+_1$ states of $N=83$ isotones.


title: Accurate Shear Measurement with Faint Sources

abstract:
  For cosmic shear to become an accurate cosmological probe, systematic errors
in the shear measurement method must be unambiguously identified and corrected
for. Previous work of this series has demonstrated that cosmic shears can be
measured accurately in Fourier space in the presence of background noise and
finite pixel size, without assumptions on the morphologies of galaxy and PSF.
The remaining major source of error is source Poisson noise, due to the
finiteness of source photon number. This problem is particularly important for
faint galaxies in space-based weak lensing measurements, and for ground-based
images of short exposure times. In this work, we propose a simple and rigorous
way of removing the shear bias from the source Poisson noise. Our noise
treatment can be generalized for images made of multiple exposures through
MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a
large ensemble of mock galaxy images of unrestricted morphologies, we show that
our shear measurement method can achieve sub-percent level accuracy even for
images of signal-to-noise ratio less than 5 in general, making it the most
promising technique for cosmic shear measurement in the ongoing and upcoming
large scale galaxy surveys.


title:
Conservative, Proportional and Optimistic Contextual Discounting in the
  Belief Functions Theory

abstract:
  Information discounting plays an important role in the theory of belief
functions and, generally, in information fusion. Nevertheless, neither
classical uniform discounting nor contextual cannot model certain use cases,
notably temporal discounting. In this article, new contextual discounting
schemes, conservative, proportional and optimistic, are proposed. Some
properties of these discounting operations are examined. Classical discounting
is shown to be a special case of these schemes. Two motivating cases are
discussed: modelling of source reliability and application to temporal
discounting.


title: Canonical formalism of bigravity

abstract:
  We construct the Hamiltonian formalism of bigravity for the potential of a
general form. We find conditions on this potential and prove that under these
conditions the formalism is equivalent to the one constructed with the
celebrated dRGT-potential.


title: Formation of silicon oxide grains at low temperature

abstract:
  The formation of grains in the interstellar medium, i.e., at low temperature,
has been proposed as a possibility to solve the lifetime problem of cosmic
dust. This process lacks a firm experimental basis, which is the goal of this
study. We have investigated the condensation of SiO molecules at low
temperature using neon matrix and helium droplet isolation techniques. The
energies of SiO polymerization reactions have been determined experimentally
with a calorimetric method and theoretically with calculations based on the
density functional theory. The combined experimental and theoretical values
have revealed the formation of cyclic (SiO)$_k$ ($k$ = 2--3) clusters inside
helium droplets at $T$ = 0.37 K. Therefore, the oligomerization of SiO
molecules is found to be barrierless and is expected to be fast in the
low-temperature environment of the interstellar medium on the surface of dust
grains. The incorporation of numerous SiO molecules in helium droplets leads to
the formation of nanoscale amorphous SiO grains. Similarly, the annealing and
evaporation of SiO-doped Ne matrices lead to the formation of solid amorphous
SiO on the substrate. The structure and composition of the grains were
determined by infrared absorption spectroscopy, transmission electron
microscopy, and energy-dispersive X-ray spectroscopy. Our results support the
hypothesis that interstellar silicates \textbf{can be formed} in the low
temperature regions of the interstellar medium by accretion through barrierless
reactions.


title:
A classification of disjoint unions of two or three copies of the free
  monogenic semigroup

abstract:
  We prove that, up to isomorphism and anti-isomorphism, there are only two
semigroups which are the union of two copies of the free monogenic semigroup.
Similarly, there are only nine semigroups which are the union of three copies
of the free monogenic semigroup. We provide finite presentations for each of
these semigroups.


title:
Singularity formation for the incompressible Hall-MHD equations without
  resistivity

abstract:
  In this paper we show that the incompressible Hall-MHD system without
resistivity is not globally in time well-posed in any Sobolev space
$H^{m}(\mathbb{R}^3)$ for any $m>\frac{7}{2}$. Namely, either the system is
locally ill-posed in $H^{m}(\mathbb{R}^3)$, or it is locally well-posed, but
there exists an initial data in $H^{m}(\mathbb{R}^3)$, for which the
$H^{m}(\mathbb{R}^3)$ norm of solution blows-up in finite time if $m>7/2$.
  In the latter case we choose an axisymmetric initial data
$u_0(x)=u_{0r}(r,z)e_r+ b_{0z}(r,z)e_z$ and
$B_0(x)=b_{0\theta}(r,z)e_{\theta}$, and reduce the system to the axisymmetric
setting. If the convection term survives sufficiently long time, then the Hall
term generates the singularity on the axis of symmetry and we have
  $ \lim\sup_{t\to t_*} \sup_{z\in \Bbb R} |\partial_z\partial_r
b_\theta(r=0,z)|=\infty$ for some $t_*>0$.


title: Bar 1-Visibility Graphs and their relation to other Nearly Planar Graphs

abstract:
  A graph is called a strong (resp. weak) bar 1-visibility graph if its
vertices can be represented as horizontal segments (bars) in the plane so that
its edges are all (resp. a subset of) the pairs of vertices whose bars have a
$\epsilon$-thick vertical line connecting them that intersects at most one
other bar.
  We explore the relation among weak (resp. strong) bar 1-visibility graphs and
other nearly planar graph classes. In particular, we study their relation to
1-planar graphs, which have a drawing with at most one crossing per edge;
quasi-planar graphs, which have a drawing with no three mutually crossing
edges; the squares of planar 1-flow networks, which are upward digraphs with
in- or out-degree at most one. Our main results are that 1-planar graphs and
the (undirected) squares of planar 1-flow networks are weak bar 1-visibility
graphs and that these are quasi-planar graphs.


title: Self-Dual Chiral Boson: Augmented Superfield Approach

abstract:
  We exploit the standard tools and techniques of the augmented version of
Bonora-Tonin (BT) superfield formalism to derive the off-shell nilpotent and
absolutely anticommuting (anti-)BRST and (anti-)co-BRST symmetry
transformations for the Becchi-Rouet-Stora-Tyutin (BRST) invariant Lagrangian
density of a self-dual bosonic system. In the derivation of the full set of the
above transformations, we invoke the (dual-)horizontality conditions,
(anti-)BRST and (anti-)co-BRST invariant restrictions on the superfields that
are defined on the (2, 2)-dimensional supermanifold. The latter is
parameterized by the bosonic variable x^\mu\,(\mu = 0,\, 1) and a pair of
Grassmanian variables \theta and \bar\theta (with \theta^2 = \bar\theta^2 = 0
and \theta\bar\theta + \bar\theta\theta = 0). The dynamics of this system is
such that, instead of the full (2, 2) dimensional superspace coordinates
(x^\mu, \theta, \bar\theta), we require only the specific (1, 2)-dimensional
super-subspace variables (t, \theta, \bar\theta) for its description. This is a
novel observation in the context of superfield approach to BRST formalism. The
application of the dual-horizontality condition, in the derivation of a set of
proper (anti-)co-BRST symmetries, is also one of the new ingredients of our
present endeavor where we have exploited the augmented version of superfield
formalism which is geometrically very intuitive.


title:
Multiwavelength observations of the gamma-ray emitting narrow-line
  Seyfert 1 PMN J0948+0022 in 2011

abstract:
  We report on radio-to-gamma-ray observations during 2011 May-September of PMN
J0948+0022, the first narrow-line Seyfert 1 (NLSy1) galaxy detected in
gamma-rays by Fermi-LAT. Strong variability was observed in gamma-rays, with
two flaring periods peaking on 2011 June 20 and July 28. The variability
observed in optical and near-infrared seems to have no counterpart in
gamma-rays. This different behaviour could be related to a bending and
inhomogeneous jet or a turbulent extreme multi-cell scenario. The radio spectra
showed a variability pattern typical of relativistic jets.
  The XMM spectrum shows that the emission from the jet dominates above 2 keV,
while a soft X-ray excess is evident in the low-energy part of the X-ray
spectrum. Models where the soft emission is partly produced by blurred
reflection or Comptonisation of the thermal disc emission provide good fits to
the data. The X-ray spectral slope is similar to that found in radio-quiet
NLSy1, suggesting that a standard accretion disc is present, as expected from
the high accretion rate. Except for the soft X-ray excess, unusual in
jet-dominated AGNs, PMN J0948+0022 shows all characteristics of the blazar
class.


title:
A Data-Driven Edge-Preserving D-bar Method for Electrical Impedance
  Tomography

abstract:
  In Electrical Impedance Tomography (EIT), the internal conductivity of a body
is recovered via current and voltage measurements taken at its surface. The
reconstruction task is a highly ill-posed nonlinear inverse problem, which is
very sensitive to noise, and requires the use of regularized solution methods,
of which D-bar is the only proven method. The resulting EIT images have low
spatial resolution due to smoothing caused by low-pass filtered regularization.
In many applications, such as medical imaging, it is known \emph{a priori} that
the target contains sharp features such as organ boundaries, as well as
approximate ranges for realistic conductivity values. In this paper, we use
this information in a new edge-preserving EIT algorithm, based on the original
D-bar method coupled with a deblurring flow stopped at a minimal data
discrepancy. The method makes heavy use of a novel data fidelity term based on
the so-called {\em CGO sinogram}. This nonlinear data step provides superior
robustness over traditional EIT data formats such as current-to-voltage
matrices or Dirichlet-to-Neumann operators, for commonly used current patterns.


title:
A basis construction of the extended Catalan and Shi arrangements of the
  type $A_{2}$

abstract:
  In [9], Terao proved the freeness of multi-Coxeter arrangements with constant
multiplicities by giving an explicit construction of bases. Combining it with
algebro-geometric method, Yoshinaga proved the freeness of the extended Catalan
and Shi arrangements in [11]. However, there have been no explicit
constructions of the bases for the logarithmic derivation modules of the
extended Catalan and Shi arrangements. In this paper, we give the first
explicit construction of them when the root system is of the type $A_2$.


title: The vertex-cut-tree of Galton-Watson trees converging to a stable tree

abstract:
  We consider a fragmentation of discrete trees where the internal vertices are
deleted independently at a rate proportional to their degree. Informally, the
associated cut-tree represents the genealogy of the nested connected components
created by this process. We essentially work in the setting of Galton-Watson
trees with offspring distribution belonging to the domain of attraction of a
stable law of index $\alpha\in(1,2)$. Our main result is that, for a sequence
of such trees $\mathcal{T}_n$ conditioned to have size $n$, the corresponding
rescaled cut-trees converge in distribution to the stable tree of index
$\alpha$, in the sense induced by the Gromov-Prokhorov topology. This gives an
analogue of a result obtained by Bertoin and Miermont in the case of
Galton-Watson trees with finite variance.


title:
Molecular motors transporting cargos in viscoelastic cytosol: how to
  beat subdiffusion with a power stroke?

abstract:
  Anomalously slow passive diffusion, $\langle \delta x^2(t)\rangle\simeq
t^{\alpha}$, with $0<\alpha<1$, of larger tracers such as messenger RNA and
endogenous submicron granules in the cytoplasm of living biological cells has
been demonstrated in a number of experiments and has been attributed to the
viscoelastic physical nature of the cellular cytoplasm. This finding provokes
the question to which extent active intracellular transport is affected by this
viscoelastic environment: does the subdiffusion of free submicron cargo such as
vesicles and organelles always imply anomalously slow transport by molecular
motors such as kinesins, that is, directed transport characterized by a
sublinear growth of the mean distance, $\langle x(t)\rangle\simeq
t^{\alpha_{\rm eff}}$, with $0<\alpha_{\rm eff}<1$? Here we study a generic
model approach combining the commonly accepted two-state Brownian ratchet model
of kinesin motors based on the continuous-state diffusion along microtubule
driven by a flashing binding potential. The motor is elastically coupled to a
cargo particle, which in turn is subject to the viscoelastic cytoplasmic
environment. Depending on the physical parameters of cargo size, loading force,
amplitude of the binding potential, and the turnover frequency of the molecular
motor, the transport can be both normal ($\alpha_{\rm eff}=1$) and anomalous
($\alpha\leq \alpha_{\rm eff}<1$). In particular, we demonstrate in detail how
highly efficient normal motor transport can emerge despite the anomalously slow
passive diffusion of cargo particles, and how the active motion of the same
motor in the same cell may turn anomalously slow when the parameters are
changed.


title: Noether's Second Theorem on natural bundles

abstract:
  Following work by I. Anderson, in this note we present a formulation of
Noether's Second Theorem that is valid on any natural bundle.


title: Evolutionary comparison between viral lysis rate and latent period

abstract:
  Marine viruses shape the structure of the microbial community. They are,
thus, a key determinant of the most important biogeochemical cycles in the
planet. Therefore, a correct description of the ecological and evolutionary
behavior of these viruses is essential to make reliable predictions about their
role in marine ecosystems. The infection cycle, for example, is indistinctly
modeled in two very different ways. In one representation, the process is
described including explicitly a fixed delay between infection and offspring
release. In the other, the offspring are released at exponentially distributed
times according to a fixed release rate. By considering obvious quantitative
differences pointed out in the past, the latter description is widely used as a
simplification of the former. However, it is still unclear how the dichotomy
"delay versus rate description" affects long-term predictions of host-virus
interaction models. Here, we study the ecological and evolutionary implications
of using one or the other approaches, applied to marine microbes. To this end,
we use mathematical and eco-evolutionary computational analysis. We show that
the rate model exhibits improved competitive abilities from both ecological and
evolutionary perspectives in steady environments. However, rate-based
descriptions can fail to describe properly long-term microbe-virus
interactions. Moreover, additional information about trade-offs between
life-history traits is needed in order to choose the most reliable
representation for oceanic bacteriophage dynamics. This result affects deeply
most of the marine ecosystem models that include viruses, especially when used
to answer evolutionary questions.


title: Dynamics of a localized spin excitation close to the spin-helix regime

abstract:
  The time evolution of a local spin excitation in a (001)-confined
two-dimensional electron gas subjected to Rashba and Dresselhaus spin-orbit
interactions of similar strength is investigated theoretically and compared
with experimental data. Specifically, the consequences of the finite spatial
extension of the initial spin polarization is studied for non-balanced Rashba
and Dresselhaus terms and for finite cubic Dresselhaus spin-orbit interaction.
We show that the initial out-of-plane spin polarization evolves into a helical
spin pattern with a wave number that gradually approaches the value $q_0$ of
the persistent spin helix mode. In addition to an exponential decay of the spin
polarization that is proportional to both the spin-orbit imbalance and the
cubic Dresselhaus term, the finite width $w$ of the spin excitation reduces the
spin polarization by a factor that approaches $\exp(-q_0^2 w^2/2)$ at longer
times.


title:
Gaussian linear state-space model for wind fields in the North-East
  Atlantic

abstract:
  A space-time model for wind fields is proposed. It aims at simulating
realistic wind conditions with a focus on reproducing the space-time motions of
the meteorological systems. A Gaussian linear state-space model is used where
the latent state may be interpreted as regional wind condition and the
observation equation links regional and local scales. Parameter estimation is
performed by combining a method of moment and the EM algorithm whose
performances are discussed using simulation studies. The model is fitted to
6-hourly reanalysis data in the North-East Atlantic. It is shown that the
fitted model is interpretable and provide a good description of important
properties of the space-time covariance function of the data, such as the non
full-symmetry induced by prevailing flows in this area.


title:
Nonmagnetic and ferromagnetic fcc cerium studied with one-electron
  methods

abstract:
  Density functional theory was used to study the nonmagnetic (NM) and
ferromagnetic (FM) phases of face-centered cubic cerium. Functionals of four
levels of approximations for the exchange-correlation energy were used: LDA,
PBE, LDA/PBE+$U$, and YS-PBEh. The latter two contain an adjustable parameter,
the onsite Coulomb repulsion parameter $U$ for LDA/PBE+$U$ and the fraction
$\alpha_x$ of Hartree-Fock exchange for YS-PBEh, which were varied in order to
study their influence on the results. By supposing that, as a first
approximation, the NM and FM solutions can be identified to the observed
$\alpha$ and $\gamma$ phases, respectively, it is concluded that while a small
value of $U$ or $\alpha_x$ leads to the correct trend for the stability
ordering of the two phases, larger values are necessary for a more appropriate
(but still not satisfying) description of the electronic structure.


title: Mechanism of structural phase transitions in KCrF3

abstract:
  We study the origin of the cubic to tetragonal and tetragonal to monoclinic
structural transitions in KCrF3, and the associated change in orbital order,
paying particular attention to the relevance of super-exchange in both phases.
We show that super-exchange is not the main mechanism driving these
transitions. Specifically, it is not strong enough to be responsible for the
high-temperature cubic to tetragonal transition and does not yield the type of
orbital order observed in the monoclinic phase. The energy difference between
the tetragonal and the monoclinic structure is tiny, and most likely results
from the interplay between volume, covalency, and localization effects. The
transition is rather driven by Slater exchange than super-exchange.
Nevertheless, once the monoclinic distortions are present, super-exchange helps
in stabilizing the low symmetry structure. The orbital order we obtain for this
monoclinic phase is consistent with the magnetic transition at 80 K.


title: Curve network interpolation by $C^1$ quadratic B-spline surfaces

abstract:
  In this paper we investigate the problem of interpolating a B-spline curve
network, in order to create a surface satisfying such a constraint and defined
by blending functions spanning the space of bivariate $C^1$ quadratic splines
on criss-cross triangulations. We prove the existence and uniqueness of the
surface, providing a constructive algorithm for its generation. We also present
numerical and graphical results and comparisons with other methods.


title: Shaping the distribution of vertical velocities of antihydrogen in GBAR

abstract:
  GBAR is a project aiming at measuring the free fall acceleration of gravity
for antimatter, namely antihydrogen atoms ($\overline{\mathrm{H}}$). Precision
of this timing experiment depends crucially on the dispersion of initial
vertical velocities of the atoms as well as on the reliable control of their
distribution. We propose to use a new method for shaping the distribution of
vertical velocities of $\overline{\mathrm{H}}$, which improves these factors
simultaneously. The method is based on quantum reflection of elastically and
specularly bouncing $\overline{\mathrm{H}}$ with small initial vertical
velocity on a bottom mirror disk, and absorption of atoms with large initial
vertical velocities on a top rough disk. We estimate statistical and systematic
uncertainties, and show that the accuracy for measuring the free fall
acceleration $\overline{g}$ of $\overline{\mathrm{H}}$ could be pushed below
$10^{-3}$ under realistic experimental conditions.


title: Parametric dependence of irregular conformal block

abstract:
  Irregular conformal block is an important tool to study a new type of
conformal theories, which can be constructed as the colliding limit of the
regular conformal block. The irregular conformal block is realized as the
$\beta$-deformed Penner matrix model whose partition function is regarded as
the inner product of the irregular modules. The parameter dependence of the
inner product is obtained explicitly using the loop equation with close
attention to singularities in the parameter space. It is noted that the exact
singular structure of the parameter space in general can be found using a very
simple and powerful method which uses the flow equations of the partition
function together with the hierarchical structure of the singularity. This
method gives the exact expression to all orders of large $N$ expansion without
using the explicit contour integral of the filling fraction.


title: Geometrical aspects of jet quenching in JEWEL

abstract:
  In this publication the performance of the Monte Carlo event generator JEWEL
in non-central heavy-ion collisions is investigated. JEWEL is a consistent
perturbative framework for jet evolution in the presence of a dense medium. It
yields a satisfactory description of a variety of jet observables in central
collisions at the LHC, although so far with a simplistic model of the medium.
Here, it is demonstrated that also jet measurements in non-central collisions,
and in particular the dependence of the jet suppression on the angle relative
to the reaction plane, are reproduced by the same model.


title:
RNA-based regulation: dynamics and response to perturbations of
  competing RNAs

abstract:
  The observation that, through a titration mechanism, microRNAs (miRNAs) can
act as mediators of effective interactions among their common targets
(competing endogenous RNAs or ceRNAs) has brought forward the idea ('ceRNA
hypothesis') that RNAs can regulate each other in extended 'cross-talk'
networks. Such an ability might play a major role in post-transcriptional
regulation (PTR) in shaping a cell's protein repertoire. Recent work focusing
on the emergent properties of the cross-talk networks has emphasized the high
flexibility and selectivity that may be achieved at stationarity. On the other
hand, dynamical aspects, possibly crucial on the relevant time scales, are far
less clear. We have carried out a dynamical study of the ceRNA hypothesis on a
model of PTR. Sensitivity analysis shows that ceRNA cross-talk is dynamically
extended, i.e. it may take place on time scales shorter than those required to
achieve stationairity even in cases where no cross-talk occurs in the steady
state, and is possibly amplified. Besides, in case of large, transfection-like
perturbations the system may develop strongly non-linear, threshold response.
Finally, we show that the ceRNA effect provides a very efficient way for a cell
to achieve fast positive shifts in the level of a ceRNA when necessary. These
results indicate that competition for miRNAs may indeed provide an elementary
mechanism to achieve system-level regulatory effects on the transcriptome over
physiologically relevant time scales.

categories: q-bio.MN cond-mat.dis-nn cond-mat.stat-mech q-bio.GN q-bio.QM


title:
Quantum simulation of bosonic-fermionic non-interacting particles in
  disordered systems via quantum walk

abstract:
  We report on the theoretical analysis of bosonic and fermionic
non-interacting systems in a discrete two-particle quantum walk affected by
different kinds of disorder. We considered up to 100-step QWs with a spatial,
temporal and space-temporal disorder observing how the randomness and the
wavefunction symmetry non-trivially affect the final spatial probability
distribution, the transport properties and the Shannon entropy of the walkers.


title:
Irreducible modules over Witt algebras $\mathcal{W}_n$ and over
  $\mathfrak{sl}_{n+1}(\mathbb{C})$

abstract:
  In this paper, by using the "twisting technique" we obtain a class of new
modules $A_b$ over the Witt algebras $\mathcal{W}_n$ from modules $A$ over the
Weyl algebras $\mathcal{K}_n$ (of Laurent polynomials) for any
$b\in\mathbb{C}$. We give the necessary and sufficient conditions for $A_b$ to
be irreducible, and determine the necessary and sufficient conditions for two
such irreducible $\mathcal{W}_n$-modules to be isomorphic. Since
$\sl_{n+1}(\mathbb{C})$ is a subalgebra of $\mathcal{W}_n$, all the above
irreducible $\mathcal{W}_n$-modules $A_b$ can be considered as
$\sl_{n+1}(\mathbb{C})$-modules. For a class of such
$\sl_{n+1}(\mathbb{C})$-modules, denoted by
$\Omega_{1-a}(\lambda_1,\lambda_2,\cdots,\lambda_n)$ where $a\in\mathbb{C},
\lambda_1,\lambda_2,\cdots,\lambda_n \in \mathbb{C}^*$, we determine the
necessary and sufficient conditions for these $\sl_{n+1}(\mathbb{C})$-modules
to be irreducible. If the $\sl_{n+1}(\mathbb{C})$-module
$\Omega_{1-a}(\lambda_1,\lambda_2,\cdots,\lambda_n)$ is reducible, we prove
that it has a unique nontrivial submodule $W_{1-a}(\lambda_1,
\lambda_2,...\lambda_n)$ and the quotient module is the finite dimensional
$\sl_{n+1}(\mathbb{C})$-module with highest weight $m\Lambda_n$ for some
non-negative integer $m\in \Z_+$. The necessary and sufficient conditions for
two $\mathfrak{sl}_{n+1}(\mathbb{C})$-modules
$\Omega_{1-a}(\lambda_1,\lambda_2,\cdots,\lambda_n)$ and $W_{1-a}(\lambda_1,
\lambda_2,...\lambda_n)$ to be isomorphic are also determined. The irreducible
$\mathfrak{sl}_{n+1}(\mathbb{C})$-modules $\Omega_{1-a}(\lambda_1,
\lambda_2,...\lambda_n)$ and $W_{1-a}(\lambda_1, \lambda_2,...\lambda_n)$ are
new.


title:
Emerging problems in approximation theory for the numerical solution of
  nonlinear PDEs of integrable type

abstract:
  In this paper we present some open problems pertaining to the approximation
theory involved in the solution of the important class of Nonlinear Partial
Differential Equations (NPDEs) of integrable type. For this class of NPDEs, any
Initial Value Problem (IVP) can be theoretically solved by the Inverse
Scattering Transform (IST) technique whose main steps involve the solution of
Volterra equations with structured kernels on unbounded domains, the solution
of Fredholm integral equations and the identification of coefficients and
parameters of monomial-exponential sums. The aim of this paper is twofold:
propose a method for solving the above mentioned problems under particular
hypothesis and arouse interest in these problems in order to develop an
effective method which works under more general assumptions.


title: Transitive parallelism of residues in buildings

abstract:
  We study the buildings in which parallelism of residues is an equivalence
relation. If the building admits a group action, we describe how parallel
residues are related to residues with equal stabilizers. This permits to
retrieve the fact that in a Coxeter group or in a graph product, intersections
of parabolic subgroups are parabolic.


title: Word Emdeddings through Hellinger PCA

abstract:
  Word embeddings resulting from neural language models have been shown to be
successful for a large variety of NLP tasks. However, such architecture might
be difficult to train and time-consuming. Instead, we propose to drastically
simplify the word embeddings computation through a Hellinger PCA of the word
co-occurence matrix. We compare those new word embeddings with some well-known
embeddings on NER and movie review tasks and show that we can reach similar or
even better performance. Although deep learning is not really necessary for
generating good word embeddings, we show that it can provide an easy way to
adapt embeddings to specific tasks.


title:
Improvements to the Prototype Micro-Brittle Linear Elasticity Model of
  Peridynamics

abstract:
  This paper assesses the accuracy and convergence of the linear-elastic,
bond-based Peridynamic model with brittle failure, known as the prototype
micro-brittle (PMB) model. We investigate the discrete equations of this model,
suitable for numerical implementation. It is shown that the widely used
discretization approach incurs rather large errors. Motivated by this
observation, a correction is proposed, which significantly increases the
accuracy by cancelling errors associated with the discretization. As an
additional result, we derive equations to treat the interactions between
differently sized particles, i.e., a non-homogeneous discretization spacing.
This presents an important step forward for the applicability of the PMB model
to complex geometries, where it is desired to model interesting parts with a
fine resolution (small particle spacings) and other parts with a coarse
resolution in order to gain numerical efficiency. Validation of the corrected
Peridynamic model is performed by comparing longitudinal sound wave propagation
velocities with exact theoretical results. We find that the corrected approach
correctly reproduces the sound wave velocity, while the original approach
severely overestimates this quantity. Additionally, we present simulations for
a crack growth problem which can be analytically solved within the framework of
Linear Elastic Fracture Mechanics Theory. We find that the corrected
Peridynamics model is capable of quantitatively reproducing crack initiation
and propagation.


title: Is AdS stable?

abstract:
  It has recently been conjectured that the Anti-de Sitter space is unstable
under arbitrarily small perturbations. This article (based on my plenary talk
of the same title at the conference GR20 in Warsaw) briefly reviews numerical
and analytical evidence supporting this conjecture, putting emphasis on weak
turbulence as a driving mechanism of instability.


title:
Pinning of thermal excitations at defects in artificial spin-ice dipolar
  arrays: A theoretical investigation

abstract:
  In this theoretical investigation we address the effect of defects on thermal
excitations in square-lattice dipolar arrays. The geometry of the nanomagnets,
adopted from recent experiments [A. Farhan \textit{et al.}, Nature Phys.\
\textbf{9} (2013) 375], allows for thermal activation at room temperature. It
turns out that excitations can efficiently be pinned at defects. Furthermore,
ferromagnetic strings of nanomagnets that connect a pair of defects can be
produced; their lengths are closely related to the distance of the defects and
the topology of the magnetic ground-state configuration. We discuss various
types of defects, all of which can be produced by microstructuring techniques.


title: A lower bound for the uniform Schoenberg operator

abstract:
  We present an estimate for the lower bound for the Schoenberg operator with
equidistant knots in terms of the second order modulus of smoothness. We
investigate the behaviour of iterates of the Schoenberg operator and in
addition, we show an upper bound of the second order derivative of these
iterates. Finally, we prove the equivalence between the approximation error and
the second order modulus of smoothness.


title:
Three Metrics for Measuring User Engagement with Online Media and a
  YouTube Case Study

abstract:
  This technical report discusses three metrics of user engagement with online
media. They are Commenting frequency, Voting frequency, and Voting balance.
These relative figures can be derived from established, basic statistics
available for many services, prominently YouTube. The paper includes case a
study of popular YouTube videos to illustrate the characteristics and
usefulness of the measures. The study documents the range of observed values
and their relationships. The empirical sample shows the three measures to be
only moderately correlated with the original statistics despite the common
numerators and denominators. The paper concludes by discussing future
applications and the needs of the quantification of user interaction with new
media services.


title: My First Deep Learning System of 1991 + Deep Learning Timeline 1962-2013

abstract:
  Deep Learning has attracted significant attention in recent years. Here I
present a brief overview of my first Deep Learner of 1991, and its historic
context, with a timeline of Deep Learning highlights.


title:
Very general monomial valuations of $\mathbb{P}^2$ and a Nagata type
  conjecture

abstract:
  It is well known that multi-point Seshadri constants for a small number $s$
of points in the projective plane are submaximal. It is predicted by the Nagata
conjecture that their values are maximal for $s\geq 9$ points. Tackling the
problem in the language of valuations one can make sense of $s$ points for any
positive real $s\geq 1$. We show somewhat surprisingly that a Nagata-type
conjecture should be valid for $s\geq 8+1/36$ points and we compute explicitly
all Seshadri constants (expressed here as the asymptotic maximal vanishing
element) for $s\leq 7+1/9$.


title: Non-trivial order parameter in Sr$_{2}$IrO$_{4}$

abstract:
  Electronic structure calculations obtained with an approach with density
functional theory with an enhanced local Coulomb interaction, DFT+$U$, are
presented for the relativistic magnetic insulator Sr$_{2}$IrO$_{4}$. The
results are in accordance with experiments with a band gap and a small moment
anti-ferromagnetic ground state. This solution is thereafter thoroughly
analyzed in terms of Landau theory where it is found that the ordered magnetic
moments only form a secondary order parameter while the primary order parameter
is a higher order magnetic multipole of rank five. It is further observed that
the electronic structure in the presence of this order parameter is related to
the earlier proposed $j_\mathrm{eff}=1/2$ model, but in contrast to that model
the present picture can naturally explain the small magnitude of the ordered
magnetic moments.


title:
Enriched Performance on Wireless Sensor Network using Fuzzy based
  Clustering Technique

abstract:
  The wireless sensor networks combines sensing, computation, and communication
into a single small device. These devices depend on battery power and may be
placed in hostile environments replacing them becomes a tedious task. Thus
improving the energy of these networks becomes important. Clustering in
wireless sensor network looks several challenges such as selection of an
optimal group of sensor nodes as cluster, optimum selection of cluster head,
energy balanced optimal strategy for rotating the role of cluster head in a
cluster, maintaining intra and inter cluster connectivity and optimal data
routing in the network.
  In this paper, we study a protocol supporting an energy efficient clustering,
cluster head selection and data routing method to extend the lifetime of sensor
network. Simulation results demonstrate that the proposed protocol prolongs
network lifetime due to the use of efficient clustering, cluster head selection
and data routing. The results of simulation show that at the end of some
certain part of running the EECS and Fuzzy based clustering algorithm increases
the number of alive nodes comparing with the LEACH and HEED methods and this
can lead to an increase in sensor network lifetime. By using the EECS method
the total number of messages received at base station is increased when
compared with LEACH and HEED methods. The Fuzzy based clustering method
compared with the K-Means Clustering by means of iteration count and time taken
to die first node in wireless sensor network, as the result shows that the
fuzzy based clustering method perform well than kmeans clustering methods.