title:
On a one-dimensional quadratic operator pencil with a small periodic
  perturbation

abstract:
  We consider a quadratic operator pencil with a small periodic perturbation
multiplied by the spectral parameter. It is motivated, in particular, by a
one-dimensional Klein-Gordon equation with a time-parity-symmetric
perturbation. We study in details the structure of the considered operator
pencil. We show that its essential spectrum has a band structure and at certain
thresholds, the bands bifurcate into small parabolas. We then study how the
isolated limiting eigenvalues behave under the perturbation. We show that if
zero is a limiting isolated eigenvalue, under the perturbation it remains an
eigenvalue but an additional isolated eigenvalue can emerge from zero. The most
part of the paper is devoted to studying the isolated eigenvalues converging to
the essential spectrum. We establish sufficient conditions for the existence
and absence of such eigenvalues and in the case of the existence, we calculate
the leading terms of their asymptotic expansions.


title:
Task-space coordinated tracking of multiple heterogeneous manipulators
  via controller-estimator approaches

abstract:
  This paper studies the task-space coordinated tracking of a time-varying
leader for multiple heterogeneous manipulators (MHMs), containing redundant
manipulators and nonredundant ones. Different from the traditional coordinated
control, distributed controller-estimator algorithms (DCEA), which consist of
local algorithms and networked algorithms, are developed for MHMs with
parametric uncertainties and input disturbances. By invoking differential
inclusions, nonsmooth analysis, and input-to-state stability, some conditions
(including sufficient conditions, necessary and sufficient conditions) on the
asymptotic stability of the task-space tracking errors and the subtask errors
are developed. Simulation results are given to show the effectiveness of the
presented DCEA.


title:
Higher order tangents and Higher order Laplacians on Sierpinski Gasket
  Type Fractals

abstract:
  We study higher order tangents and higher order Laplacians on p.c.f.
self-similar sets with fully symmetric structures, such as $D3$ or $D4$
symmetric fractals. Firstly, let $x$ be a vertex point in the graphs that
approximate the fractal, we prove that for any $f$ defined near $x$, the higher
oder weak tangent of $f$ at $x$, if exists, is the uniform limit of local
multiharmonic functions that agree with $f$ in some sense near $x$. Secondly,
we prove that the higher order Laplacian on a fractal can be expressible as a
renormalized uniform limit of higher order graph Laplacians on the graphs that
approximate the fractal. The main technical tool is the theory of local
multiharmonic functions and local monomials analogous to $(x-x_0)^j/j!$. The
results in this paper are closely related to the theory of local Taylor
approximations, splines and entire analytic functions. Some of our results can
be extended to general p.c.f. fractals. In Appendix of the paper, we provide a
recursion algorithm for the exact calculations of the boundary values of the
monomials for $D3$ or $D4$ symmetric fractals, which is shorter and more direct
than the previous work on the Sierpinski gasket.


title: Cosmic Shear Measurement using Autoconvolved Images

abstract:
  We study the possibility of using quadrupole moments of auto-convolved galaxy
images to measure cosmic shear. The autoconvolution of an image corresponds to
the inverse Fourier transformation of its power spectrum. The new method has
the following advantages: the smearing effect due to the Point Spread Function
(PSF) can be corrected by subtracting the quadrupole moments of the
auto-convolved PSF; the centroid of the auto-convolved image is trivially
identified; the systematic error due to noise can be directly removed in
Fourier space; the PSF image can also contain noise, the effect of which can be
similarly removed. With a large ensemble of simulated galaxy images, we show
that the new method can reach a sub-percent level accuracy in general
conditions, albeit with increasingly large stamp size for galaxies of less
compact profiles.


title: Reduced contragredient Lie algebras and PC Lie algebras

abstract:
  The first aim of this paper is to show that any finite-dimensional reductive
Lie algebra and its finite-dimensional completely reducible representation can
be embedded into some PC Lie algebra. The second aim is to find the structure
of a PC Lie algebra.


title:
Latency-Optimal Uplink Scheduling Policy in Training-based Large-Scale
  Antenna Systems

abstract:
  In this paper, an uplink scheduling policy problem to minimize the network
latency, defined as the air-time to serve all of users with a
quality-of-service (QoS), under an energy constraint is considered in a
training-based large-scale antenna systems (LSAS) employing a simple linear
receiver. An optimal algorithm providing the exact latency-optimal uplink
scheduling policy is proposed with a polynomial-time complexity. Via numerical
simulations, it is shown that the proposed scheduling policy can provide
several times lower network latency over the conventional ones in realistic
environments. In addition, the proposed scheduling policy and its network
latency are analyzed asymptotically to provide better insights on the system
behavior. Four operating regimes are classified according to the average
received signal quality, $\rho$, and the number of BS antennas, $M$. It turns
out that orthogonal pilots are optimal only in the regime $\rho\gg1$ and $ M\ll
\log^2\rho$. In other regimes ($\rho\ll 1$ or $ M\gg \log^2\rho$), it turns out
that non-orthogonal pilots become optimal. More rigorously, the use of
non-orthogonal pilots can reduce the network latency by a factor of $\Theta(M)$
when $\rho\ll 1$ or by a factor of $\Theta(\sqrt{M}/\log M)$ when $\rho\gg 1$
and $M\gg \log\rho$, which would be a critical guideline for designing 5G
future cellular systems.


title: Flexible Pilot Contamination Mitigation with Doppler PSD Alignment

abstract:
  Pilot contamination in the uplink (UL) can severely degrade the channel
estimation quality at the base station (BS) in a massive multi-input
multi-output (MIMO) system. Thus, it is critical to explore all possible
avenues to enable more orthogonal resources for the users to transmit
non-interfering UL pilots. In conventional designs, pilot orthogonality
typically assumes constant channel gains over time, which limits the amount of
orthogonal resources in the case of time-selective channels. To circumvent this
constraint, in this paper, we show how to enable orthogonal multiplexing of
pilots in the case of Doppler fading by aligning the power spectrum densities
(PSD) of different users. From the derived PSD aligning rules, we can see
multiple users can be sounded simultaneously without creating/suffering pilot
contamination even when these users are experiencing time-varying channels.
Furthermore, we provide analytical formulas characterizing the channel
estimation mean square error (MSE) performance. Computer simulations further
confirm us the PSD alignment can serve as one important decontamination
mechanism for the UL pilots in massive MIMO.


title:
Concentration of Measure for Radial Distributions and Consequences for
  Statistical Modeling

abstract:
  Motivated by problems in high-dimensional statistics such as mixture modeling
for classification and clustering, we consider the behavior of radial densities
as the dimension increases. We establish a form of concentration of measure,
and even a convergence in distribution, under additional assumptions. This
extends the well-known behavior of the normal distribution (its concentration
around the sphere of radius square-root of the dimension) to other radial
densities. We draw some possible consequences for statistical modeling in
high-dimensions, including a possible universality property of Gaussian
mixtures.


title:
Detecting multimuon jets from the Higgs exotic decays in the Higgs
  portal framework

abstract:
  A muon jet ($\mu$-jet) is a very special feature that consists of a cluster
of collimated muons from the decay of a fast moving light particle of mass
about $\mathcal{O}$(1 GeV). We will use this feature to search for very light
particles from rare decays of the Higgs boson. For such a small angular
separation of muons which might come from a long-lived particle, both ATLAS and
CMS could have the displaced-vertexing-reconstruction capability. We use two
simple models of the Higgs-portal type to explore the possibilities of event
topologies with two $2\mu$-jets, one $2\mu$-jet $\&$ one $4\mu$-jet, and two
$4\mu$-jets in the final state at LHC-14. We also summarize existing
constraints on these models.


title:
Experimental Observation of Topological Superconductivity and Majorana
  Zero Modes on beta-Bi2Pd Thin Films

abstract:
  Using a cryogenic scanning tunneling microscopy, we report the observation of
topologically nontrivial superconductivity on a single material of \beta-Bi2Pd
films grown by molecular beam epitaxy. The superconducting gap associated with
spinless odd-parity pairing opens on the surface and appears much larger than
the bulk one due to the Dirac-fermion enhanced parity mixing of surface pair
potential. Majorana zero modes (MZMs), supported by such superconducting
states, are identified at magnetic vortices. The superconductivity and MZMs
exhibit resistance to nonmagnetic defects, characteristic of
time-reversal-invariant topological superconductors. Our results demonstrate a
simple platform to generate, manipulate and braid MZMs for quantum computation.


title:
Interplay of Coulomb interaction and disorder in a two-dimensional
  semi-Dirac fermion system

abstract:
  It was recently found that Coulomb interaction can induce a series of
nontrivial spectral and transport properties in a two-dimensional anisotropic
Weyl semimetal. Different from graphehe that is basically an ordinary Fermi
liquid, the Coulomb interaction in this system makes the Fermi liquid
description invalid over a wide range of energy scales. We present a systematic
renormalization group analysis of the interplay of Coulomb interaction and
quenched disorder, and show that they have substantial mutual effects on each
other, which then leads to a variety of quantum phase transitions and non-Fermi
liquid behaviors. The low-energy physics of the system depends sensitively on
the effective strength of Coulomb interaction and disorder.


title: Low-Congestion Shortcuts without Embedding

abstract:
  Distributed optimization algorithms are frequently faced with solving
sub-problems on disjoint connected parts of a network. Unfortunately, the
diameter of these parts can be significantly larger than the diameter of the
underlying network, leading to slow running times. Recent work by [Ghaffari and
Hauepler; SODA'16] showed that this phenomenon can be seen as the broad
underlying reason for the pervasive $\Omega(\sqrt{n} + D)$ lower bounds that
apply to most optimization problems in the CONGEST model. On the positive side,
this work also introduced low-congestion shortcuts as an elegant solution to
circumvent this problem in certain topologies of interest. Particularly, they
showed that there exist good shortcuts for any planar network and more
generally any bounded genus network. This directly leads to fast $O(D
\log^{O(1)} n)$ distributed algorithms for MST and Min-Cut approximation, given
that one can efficiently construct these shortcuts in a distributed manner.
  Unfortunately, the shortcut construction of [Ghaffari and Hauepler; SODA'16]
relies heavily on having access to a genus embedding of the network. Computing
such an embedding distributedly, however, is a hard problem - even for planar
networks. No distributed embedding algorithm for bounded genus graphs is in
sight.
  In this work, we side-step this problem by defining a restricted and more
structured form of shortcuts and giving a novel construction algorithm which
efficiently finds a shortcut which is, up to a logarithmic factor, as good as
the best shortcut that exists for a given network. This new construction
algorithm directly leads to an $O(D \log^{O(1)} n)$-round algorithm for solving
optimization problems like MST for any topology for which good restricted
shortcuts exist - without the need to compute any embedding. This includes the
first efficient algorithm for bounded genus graphs.


title:
X-Ray observations of a subhalo associated with the NGC 4839 group
  infalling toward the Coma cluster

abstract:
  We report $Suzaku$ X-ray observations of the dark subhalo associated with the
merging group of NGC 4839 in the Coma cluster. The X-ray image exhibits an
elongated tail toward the southwest. The X-ray peak shifts approximately $1'$
away from the weak-lensing mass center toward the opposite direction of the
Coma cluster center. We investigated the temperature, normalization, pressure,
and entropy distributions around the subhalo. Excluding the X-ray tail, the
temperature beyond the truncation radius is 8-10$~\rm keV$, which is two times
higher than that of the subhalo and the X-ray tail. The pressure is nearly
uniform excluding southern part of the subhalo at two times of the truncation
radius. We computed the gas mass within the truncation radius and the X-ray
tail. While the gas fraction within the truncation radius is about 5 times
smaller than that of regular groups, the gas mass in the subhalo and the X-ray
tail to weak-lensing mass ratio is consistent with that of regular groups.
Assuming the infall velocity, $2000~\rm km~s^{-1}$, the ram pressure is 1.4
times greater than gravitational force per unit area. Assuming the
Kelvin-Helmholtz instabilities, the total lost mass is approximately
$3\times10^{11}~M_{\odot}$. If this gas had originally been within the
truncation radius, the gas mass fraction of the subhalo would have been
comparable with those of regular groups before infalling to the Coma cluster.


title: Convergences of Random Variables under Sublinear Expectations

abstract:
  In this note, we will survey the existing convergence results for random
variables under sublinear expectations, and prove some new results. Concretely,
under the assumption that the sublinear expectation has the monotone continuity
property, we will prove that $L^p$ convergence is stronger than convergence in
capacity, convergence in capacity is stronger than convergence in distribution,
and give some equivalent characterizations of convergence in distribution. In
addition, we give a dominated convergence theorem under sublinear expectations,
which may have its own interest.


title: On a splitting method for the Zakharov system

abstract:
  An error analysis of a splitting method applied to the Zakharov system is
given. The numerical method is a Lie-Trotter splitting in time that is combined
with a Fourier collocation in space to a fully discrete method. First-order
convergence in time and high-order convergence in space depending on the
regularity of the exact solution are shown for this method. The main challenge
in the analysis is to exclude a loss of spatial regularity in the numerical
solution. This is done by transforming the numerical method to new variables
and by imposing a natural CFL-type restriction on the discretization
parameters.


title:
Asymptotical stability of almost periodic solution for an impulsive
  multispecies competition-predation system with time delays on time scales

abstract:
  In this paper, we consider the almost periodic dynamics of an impulsive
multispecies Lotka-Volterra competition system with time delays on time scales.
By establishing some comparison theorems of dynamic equations with impulses and
delays on time scales, a permanence result for the model is obtained.
Furthermore, based on the permanence result, by studying the Lyapunov stability
theory of impulsive dynamic equations on time scales, we establish a criterion
for the existence and uniformly asymptotic stability of a unique positive
almost periodic solution of the system. Finally, we give an example to show the
feasibility of our main results and our example also shows that the continuous
time system and its corresponding discrete time system have the same dynamics.
Our results of this paper are completely new even if for both the case of the
time scale $\mathbb{T}=\mathbb{R}$ and the case of $\mathbb{Z}$.


title: Learning to Prevent Monocular SLAM Failure using Reinforcement Learning

abstract:
  Monocular SLAM refers to using a single camera to estimate robot ego motion
while building a map of the environment. While Monocular SLAM is a well studied
problem, automating Monocular SLAM by integrating it with trajectory planning
frameworks is particularly challenging. This paper presents a novel formulation
based on Reinforcement Learning (RL) that generates fail safe trajectories
wherein the SLAM generated outputs do not deviate largely from their true
values. Quintessentially, the RL framework successfully learns the otherwise
complex relation between perceptual inputs and motor actions and uses this
knowledge to generate trajectories that do not cause failure of SLAM. We show
systematically in simulations how the quality of the SLAM dramatically improves
when trajectories are computed using RL. Our method scales effectively across
Monocular SLAM frameworks in both simulation and in real world experiments with
a mobile robot.


title: Symmetric products and subgroup lattices

abstract:
  Let G be a finite group. We show that the rational homotopy groups of
symmetric products of the G-equivariant sphere spectrum are naturally
isomorphic to the rational homology groups of certain subcomplexes of the
subgroup lattice of G.


title:
Above-Threshold Ionization and Laser-Induced Electron Diffraction in
  Diatomic Molecules

abstract:
  Strong field photoemission and electron recollision provide a viable route to
extract electronic and nuclear dynamics from molecular targets with attosecond
temporal resolution. However, since an {\em ab-initio} treatment of even the
simplest diatomic systems is beyond today's capabilities approximate
qualitative descriptions are warranted. In this paper, we develop such a
theoretical approach to model the photoelectrons resulting from intense
laser-molecule interaction. We present a general theory for symmetric diatomic
molecules in the single active electron approximation that, amongst other
capabilities, allows adjusting both the internuclear separation and molecular
potential in a direct and simple way. More importantly we derive an analytic
approximate solution of the time dependent Schr\"odinger equation (TDSE), based
on a generalized strong field approximation (SFA) version. Using that approach
we obtain expressions for electrons emitted transition amplitudes from two
different molecular centres, and accelerated then in the strong laser field.
One innovative aspect of our theory is the fact that the dipole matrix elements
are free from non-physical gauge and coordinate system dependent terms -- this
is achieved by adapting the coordinate system, in which SFA is performed, to
the centre from which the corresponding part of the time dependent wave
function originates. Our analytic results agree very well with the numerical
solution of the full three-dimensional TDSE for the H$_2^+$ molecule. Moreover,
the theoretical model was applied to describe laser-induced electron
diffraction (LIED) measurements of O$_2^+$ molecules, obtained at ICFO, and
reproduces the main features of the experiment very well. Our approach can be
extended in a natural way to more complex molecules and multi-electron systems.


title: Generic 3D Convolutional Fusion for image restoration

abstract:
  Also recently, exciting strides forward have been made in the area of image
restoration, particularly for image denoising and single image
super-resolution. Deep learning techniques contributed to this significantly.
The top methods differ in their formulations and assumptions, so even if their
average performance may be similar, some work better on certain image types and
image regions than others. This complementarity motivated us to propose a novel
3D convolutional fusion (3DCF) method. Unlike other methods adapted to
different tasks, our method uses the exact same convolutional network
architecture to address both image denois- ing and single image
super-resolution. As a result, our 3DCF method achieves substantial
improvements (0.1dB-0.4dB PSNR) over the state-of-the-art methods that it
fuses, and this on standard benchmarks for both tasks. At the same time, the
method still is computationally efficient.


title:
Weierstrass-Enneper representation for Maximal Surfaces in Hodographic
  coordinates

abstract:
  We obtain the Weierstrass-Enneper representation for maximal graphs(whose
Gauss map is one-one) in Lorentz-Minkowski space. For this we use the method of
Barbishov and Chernikov, which they have used to find the solutions of
Born-Infeld equation in hodographic coordinates. We could use their method in
our case, because we realized that the maximal surface equation and Born-Infeld
equation are related via a wick rotation in the first variable of the
parametrising domain.


title:
Branching Brownian Motion, mean curvature flow and the motion of hybrid
  zones

abstract:
  We provide a probabilistic proof of a well known connection between a special
case of the Allen-Cahn equation and mean curvature flow. We then prove a
corresponding result for scaling limits of the spatial $\Lambda$-Fleming-Viot
process with selection, in which the selection mechanism is chosen to model
what are known in population genetics as hybrid zones. Our proofs will exploit
a duality with a system of branching (and coalescing) random walkers which is
of some interest in its own right.


title: Strongly bound Mott-Wannier Excitons in GeS and GeSe monolayers

abstract:
  The excitonic spectra of single layer GeS and GeSe are predicted by ab initio
GW-Bethe Salpeter equation calculations. G 0 W 0 calculations for the band
structures find a fundamental band gap of 2.85 eV for GeS and 1.70 eV for GeSe
monolayer. However, excitons are tightly bound, specially in GeS at the
{\Gamma} point, where the quasi-particle interactions are so strong that they
shift the {\Gamma} exciton peak energy into the visible range and below the
off-{\Gamma} exciton peak. The lowest energy excitons in both materials are
excited by light along the zigzag direction and have exciton binding energies
of 1.05 eV and 0.4 eV, respectively, but despite the strong binding, the
calculated binding energies are in agreement with a Mott-Wannier model.


title: Grounding Dynamic Spatial Relations for Embodied (Robot) Interaction

abstract:
  This paper presents a computational model of the processing of dynamic
spatial relations occurring in an embodied robotic interaction setup. A
complete system is introduced that allows autonomous robots to produce and
interpret dynamic spatial phrases (in English) given an environment of moving
objects. The model unites two separate research strands: computational
cognitive semantics and on commonsense spatial representation and reasoning.
The model for the first time demonstrates an integration of these different
strands.


title: Strain-controlled spin splitting in the conduction band of monolayer WS2

abstract:
  Spin splitting bands that arises in conduction band minimum (CBM) of WS2
monolayer (ML) play an important role in the new spin-orbit phenomena such as
spin-valley coupled electronics. However, application of strain strongly
modifies electronic properties of the WS2 ML, which is expected to
significantly affect to the properties of the spin splitting bands. Here, by
using fully-relativistic first-principles calculations based on
density-functional theory, we show that a substantial spin spliting bands
observed in the CBM is effectively controlled and tuned by applying the biaxial
strain. We also find that these spin splitting bands induce spin textures
exhibiting fully out-of-plane spin polarization in the opposite direction
between the K and Q points and their time reversals in the first Brillouin
zone. Our study clarify that the strain plays an significant role in the
spin-orbit coupling of the WS2 ML, which has very important implications in
designing future spintronics devices.


title: Contextuality with a Small Number of Observables

abstract:
  We investigate small geometric configurations that furnish observable-based
proofs of the Kochen-Specker theorem. Assuming that each context consists of
the same number of observables and each observable is shared by two contexts,
it is proved that the most economical proofs are the famous Mermin-Peres square
and the Mermin pentagram featuring, respectively, $9$ and $10$ observables,
there being no proofs using less than $9$ observables. We also propose a new
proof with $14$ observables forming a `magic' heptagram. On the other hand,
some other prominent small-size finite geometries, like the Pasch configuration
and the prism, are shown not to be contextual.


title:
A new model-independent approach for finding the arrival direction of an
  extensive air shower

abstract:
  A new accurate method for reconstructing the arrival direction of an
extensive air shower (EAS) is described. Compared to existing methods, it is
not subject to minimization of a function and, therefore, is fast and stable.
This method also does not need to know detailed curvature or thickness
structure of an EAS. It can have angular resolution of about 1 degree for a
typical surface array in central regions. Also, it has better angular
resolution than other methods in the marginal area of arrays.


title:
Existence of constant mean curvature foliation in the extended
  Schwarzschild spacetime

abstract:
  We construct a $T$-axisymmetric, spacelike, spherically symmetric, constant
mean curvature hypersurfaces foliation in the Kruskal extension with properties
that the mean curvature varies in each slice and ranges from minus infinity to
plus infinity. This family of hypersurfaces extends the CMC foliation
discussions posted by Malec and \'{O} Murchadha in 2009.


title: Random graph models for dynamic networks

abstract:
  We propose generalizations of a number of standard network models, including
the classic random graph, the configuration model, and the stochastic block
model, to the case of time-varying networks. We assume that the presence and
absence of edges are governed by continuous-time Markov processes with rate
parameters that can depend on properties of the nodes. In addition to computing
equilibrium properties of these models, we demonstrate their use in data
analysis and statistical inference, giving efficient algorithms for fitting
them to observed network data. This allows us, for instance, to estimate the
time constants of network evolution or infer community structure from temporal
network data using cues embedded both in the probabilities over time that node
pairs are connected by edges and in the characteristic dynamics of edge
appearance and disappearance. We illustrate our methods with a selection of
applications, both to computer-generated test networks and real-world examples.


title:
Slow-light-enhanced energy efficiency for the graphene microheater on
  silicon photonic crystal waveguides

abstract:
  Slow light has been widely utilized to obtain enhanced nonlinearities,
enhanced spontaneous emissions, and increased phase shifts owing to its ability
to promote light-matter interactions. By incorporating a graphene microheater
on a slow-light silicon photonic crystal waveguide, we experimentally
demonstrated an energy-efficient graphene microheater with a tuning efficiency
of 1.07 nm/mW and power consumption per free spectral range of 3.99 mW. The
rise and decay times (10% to 90%) were only 750 ns and 525 ns, which, to the
best of our knowledge, are the fastest reported response times for microheaters
in silicon photonics. The corresponding record-low figure of merit of the
device was 2.543 nW.s, which is one order of magnitude lower than results
reported in previous studies. The influences of the graphene-photonic crystal
waveguide interaction length and the shape of the graphene heater were also
investigated, providing valuable guidelines for enhancing the graphene
microheater tuning efficiency.


title:
Semiclassical evolution of quantum wave packets on the torus beyond the
  Ehrenfest time in terms of Husimi distributions

abstract:
  The semiclassical long-time limit of free evolution of quantum wave packets
on the torus is under consideration. Despite of simplicity of this system,
there are still open questions concerning the detailed description of the
evolution on time scales beyond the Ehrenfest time. One of the approaches is
based on the limiting Wigner or Husimi distributions of time-evolved wave
packets as the Planck constant tends to zero and time tends to infinity. We
derive explicit expressions for semiclassical measures corresponding to all
time scales and the corresponding stages of evolution: classical-like motion,
spreading of the wave packet, and its revivals. Also we discuss limitations of
the approach based on semiclassical measures and suggest its generalization.


title: Variational Mixture Models with Gamma or inverse-Gamma components

abstract:
  Mixture models with Gamma and or inverse-Gamma distributed mixture components
are useful for medical image tissue segmentation or as post-hoc models for
regression coefficients obtained from linear regression within a Generalised
Linear Modeling framework (GLM), used in this case to separate stochastic
(Gaussian) noise from some kind of positive or negative "activation" (modeled
as Gamma or inverse-Gamma distributed). To date, the most common choice in this
context it is Gaussian/Gamma mixture models learned through a maximum
likelihood (ML) approach; we recently extended such algorithm for mixture
models with inverse-Gamma components. Here, we introduce a fully analytical
Variational Bayes (VB) learning framework for both Gamma and/or inverse-Gamma
components. We use synthetic and resting state fMRI data to compare the
performance of the ML and VB algorithms in terms of area under the curve and
computational cost. We observed that the ML Gaussian/Gamma model is very
expensive specially when considering high resolution images; furthermore, these
solutions are highly variable and they occasionally can overestimate the
activations severely. The Bayesian Gauss-Gamma is in general the fastest
algorithm but provides too dense solutions. The maximum likelihood
Gaussian/inverse-Gamma is also very fast but provides in general very sparse
solutions. The variational Gaussian/inverse-Gamma mixture model is the most
robust and its cost is acceptable even for high resolution images. Further, the
presented methodology represents an essential building block that can be
directly used in more complex inference tasks, specially designed to analyse
MRI-fMRI data; such models include for example analytical variational mixture
models with adaptive spatial regularization or better source models for new
spatial blind source separation approaches.


title:
NNLL soft and Coulomb resummation for squark and gluino production at
  the LHC

abstract:
  We present predictions for the total cross sections for pair production of
squarks and gluinos at the LHC including a combined NNLL resummation of soft
and Coulomb gluon effects. We derive all terms in the NNLO cross section that
are enhanced near the production threshold, which include contributions from
spin-dependent potentials and so-called annihilation corrections. The NNLL
corrections at $\sqrt{s}=13$ TeV range from up to $20\%$ for squark-squark
production to $90\%$ for gluino pair production relative to the NLO results and
reduce the theoretical uncertainties of the perturbative calculation to the
$10\%$ level. Grid files with our numerical results are publicly available.


title: A Reduction theorem for $AH$ algebras with ideal property

abstract:
  Let $A$ be an $AH$ algebra, that is, $A$ is the inductive limit
$C^{*}$-algebra of
$$A_{1}\xrightarrow{\phi_{1,2}}A_{2}\xrightarrow{\phi_{2,3}}A_{3}\longrightarrow\cdots\longrightarrow
A_{n}\longrightarrow\cdots$$ with
$A_{n}=\bigoplus_{i=1}^{t_{n}}P_{n,i}M_{[n,i]}(C(X_{n,i}))P_{n,i}$, where
$X_{n,i}$ are compact metric spaces, $t_{n}$ and $[n,i]$ are positive integers,
and $P_{n,i}\in M_{[n,i]}(C(X_{n,i}))$ are projections. Suppose that $A$ has
the ideal property: each closed two-sided ideal of $A$ is generated by the
projections inside the ideal, as a closed two-sided ideal. Suppose that
$\sup_{n,i}dim(X_{n,i})<+\infty$. In this article, we prove that $A$ can be
written as the inductive limit of $$B_{1}\longrightarrow
B_{2}\longrightarrow\cdots\longrightarrow B_{n}\longrightarrow\cdots,$$ where
$B_{n}=\bigoplus_{i=1}^{s_{n}}Q_{n,i}M_{\{n,i\}}(C(Y_{n,i}))Q_{n,i}$, where
$Y_{n,i}$ are $\{pt\}$, $[0,1]$,$ S^{1}$,$ T_{II, k},$ $T_{III, k}$ and $S^{2}$
(all of them are connected simplicial complexes of dimension at most three),
$s_{n}$ and $\{n,i\}$ are positive integers and $Q_{n,i}\in
M_{\{n,i\}}(C(Y_{n,i}))$ are projections. This theorem unifies and generalizes
the reduction theorem for real rank zero $AH$ algebras due to Dadarlat and Gong
([D], [G3] and [DG]) and the reduction theorem for simple $AH$ algebras due to
Gong (see [G4]).


title: Multiple relaxation times in single-molecule magnets

abstract:
  Multiple relaxation times detected in the ac magnetic susceptibility of
several single-molecule magnets have been always assigned to extrinsic factors,
such as nonequivalent magnetic centers or effects of intermolecular
interactions in the crystal. By solving quantum relaxation equations, we prove
that the observed multiple relaxation times can be of intramolecular origin and
can show up even in single-ion metal complexes. For the latter a remarkably
good description of the coexistent two relaxation times is demonstrated on
several experimental examples. This proves the relevance of the intramolecular
mechanism of multiple relaxation times in such systems, which is even easier
justified in polynuclear magnetic complexes.


title:
On rotational surfaces with zero mean curvature in the pseudo-Euclidean
  space $\mathbb{E}_2^4$

abstract:
  In this work, we study a class of rotational surfaces in the pseudo-Euclidean
space $\mathbb{E}_2^4$ whose profile curves lie in two-dimensional planes. We
solve the differential equation that characterizes the rotational surfaces with
zero mean curvature to determine the profile curves of such rotational
surfaces. Then, we give some explicit parametrization of maximal rotational
surfaces and the timelike surfaces with zero mean curvature in
$\mathbb{E}_2^4$.


title:
Reduction to dimension two of local spectrum for $AH$ algebra with ideal
  property

abstract:
  A $C^{*}$-algebra $A$ has ideal property if any ideal $I$ of $A$ is generated
as a closed two sided ideal by the projections inside the ideal. Suppose that
the limit $C^{*}$-algebra $A$ of inductive limit of direct sums of matrix
algebras over spaces with uniformly bounded dimension has ideal property. In
this paper, we will prove that $A$ can be written as an inductive limit of
certain very special subhomogeneous algebras, namely, direct sum of dimension
drop interval algebras and matrix algebras over 2-dimensional spaces with
torsion $H^{2}$ groups.


title:
Poloidal rotation driven by nonlinear momentum transport in strong
  electrostatic turbulence

abstract:
  Virtually, all existing theoretical works on turbulent poloidal momentum
transport are based on quasilinear theory. Nonlinear poloidal momentum flux -
$\langle \tilde{v}_r \tilde{n} \tilde{v}_{\theta} \rangle$ is universally
neglected. However, in the strong turbulence regime where relative fluctuation
amplitude is no longer small, quasilinear theory is invalid. This is true at
the all-important plasma edge. In this work, nonlinear poloidal momentum flux $
\langle \tilde{v}_r \tilde{n} \tilde{v}_{\theta} \rangle $ in strong
electrostatic turbulence is calculated using Hasegawa-Mima equation, and is
compared with quasilinear poloidal Reynolds stress. A novel property is that
symmetry breaking in fluctuation spectrum is not necessary for a nonlinear
poloidal momentum flux. This is fundamentally different from the quasilinear
Reynold stress. Furthermore, the comparison implies that the poloidal rotation
drive from the radial gradient of nonlinear momentum flux is comparable to that
from the quasilinear Reynolds force. Nonlinear poloidal momentum transport in
strong electrostatic turbulence is thus not negligible for poloidal rotation
drive, and so may be significant to transport barrier formation.


title:
A note on the eigenvalues of fractional Hardy-Sobolev operator with
  indefinite weight

abstract:
  In this article, we study the eigenvalue of nonlinear $p-$fractional Hardy
operator \begin{align*} (-\Delta)_p^{\alpha}u - \mu
\frac{|u|^{p-2}u}{|x|^{p\alpha}} = \lambda V(x) |u|^{p-2}u \; \text{in}\;
\Omega, \quad u = 0 \; \mbox{in}\; \mathbb{R}^n \setminus\Omega, \end{align*}
where $n>p\alpha$, $p\geq2$, $\alpha\in(0,1)$, $0\leq \mu <C_{n,\alpha,p}$ and
$\Omega$ is a domain in $\mathbb{R}^n$ with Lipschitz boundary containing $0$.
In particular, $\Omega=\mathbb{R}^n$ is admitted. The weight function $V$ may
change sign and may have singular points. We also show that the least positive
eigenvalue is simple and it is unique associated to a non-negative
eigenfunction. Moreover, we proved that there exists a sequence of eigenvalues
$\lambda_k \to \infty$ as $k\to\infty$.


title: A classification of inductive limit $C^{*}$-algebras with ideal property

abstract:
  Let $A$ be an $AH$ algebra $A=\lim\limits_{n\to
\infty}(A_{n}=\bigoplus\limits_{i=1}\limits^{t_{n}}P_{n,i}M_{[n,i]}(C(X_{n,i}))P_{n,i},
\phi_{n,m})$, where $X_{n,i}$ are compact metric spaces, $t_{n}$ and $[n,i]$
are positive integers, and $P_{n,i}\in M_{[n,i]}(C(X_{n,i}))$ are projections.
Suppose that $A$ has the ideal property: each closed two-sided ideal of $A$ is
generated by the projections inside the ideal, as a closed two sided ideal. In
this article, we will classify all $AH$ algebras with ideal property of no
dimension growth---that is, $sup_{n,i}dim(X_{n,i})<+\infty$. This result
generalizes and unifies the classification of $AH$ algebras of real rank zero
in [EG] and [DG] and the classification of simple $AH$ algebras in [G5] and
[EGL1]. This completes one of two important possible generalizations of [EGL1]
suggested in the introduction of [EGL1]. The invariants for the classification
include the scaled ordered total $K$-group $(\underline{K}(A),
\underline{K}(A)_{+},\Sigma A)$ (as already used in real rank zero case in
[DG]), for each $[p]\in\Sigma A$, the tracial state space $T(pAp)$ of cut down
algebra $pAp$ with a certain compatibility, (which is used by [Stev] and
[Ji-Jiang] for $AI$ algebras with the ideal property), and a new ingredient,
the invariant $U(pAp)/\overline{DU(pAp)}$ with a certain compatibility
condition, where $\overline{DU(pAp)}$ is the closure of commutator subgroup
$DU(pAp)$ of the unitary group $U(pAp)$ of the cut down algebra $pAp$. In [GJL]
a counterexample is presented to show that this new ingredient must be included
in the invariant. The discovery of this new invariant is analogous to that of
the order structure on the total K-theory when one advances from the
classification of simple real rank zero $C^*$-algebras to that of non simple
real rank zero $C^*$-algebras in [G2], [Ei], [DL] and [DG] (see Introduction
below).


title:
Modelling the impact of financialization on agricultural commodity
  markets

abstract:
  We propose a stylized model of production and exchange in which long-term
investors set their production decision over a horizon {\tau} , the "time to
produce", and are liquidity constrained, while financial investors trade over a
much shorter horizon {\delta} (<< {\tau} ) and are therefore more duly informed
on the exogenous shocks affecting the production output. The equilibrium
solution proves that: (i) long-term producers modify their production decisions
to anticipate the impact of short-term investors allocations on prices; (ii)
short-term investments return a positive expected profit commensurate to the
informational advantage. While the presence of financial investors improves the
efficiency of risk allocation in the short-term and reduces price volatility,
the model shows that the aggregate effect of commodity market financialization
results in rising the volatility of both farms' default risk and production
output.


title:
Euler's partition theorem for all moduli and new companions to
  Rogers-Ramanujan-Andrews-Gordon identities

abstract:
  In this paper, we give a conjecture, which generalises Euler's partition
theorem involving odd parts and different parts for all moduli. We prove this
conjecture for two family partitions. We give $q$-difference equations for the
related generating function if the moduli is three. We provide new companions
to Rogers-Ramanujan-Andrews-Gordon identities under this conjecture.


title: On the solvability of resonance problems for nonlocal elliptic equations

abstract:
  In this article, we consider the following problem: $$ \quad \left\{
\begin{array}{lr} \quad (-\Delta)^s u = \alpha u^+ -\beta u^{-} + f(u) + h \;
\text{in}\;\Omega \quad \quad \quad \quad u =0 \; \text{on}\;
\mathbb{R}^n\setminus \Omega, \end{array} \right. $$ where $\Omega\subset
\mathbb{R}^n$ is a bounded domain with Lipschitz boundary, $n> 2s$, $0<s<1$,
$(\alpha, \beta) \in \mathbb{R}^2$, $f: \mathbb{R}\to \mathbb{R}$ is a bounded
and continuous function and $h\in L^2(\Omega)$. We prove the existence results
in two cases: First, the nonresonance case, where $(\alpha,\beta)$ is not an
element of the Fu\v{c}ik spectrum. Second, the resonance case, where
$(\alpha,\beta)$ is an element of the Fu\v{c}ik spectrum. Our existence results
follows as an application of the Saddle point Theorem. It extends some results,
well known for Laplace operator, to the nonlocal operator.


title:
The 6 $\mu$m Feature as A Tracer of Aliphatic Components of Interstellar
  Carbonaceous Grains

abstract:
  An unidentified infrared emission (UIE) feature at 6.0 $\mu$m is detected in
a number of astronomical sources showing the UIE bands. In contrast to the
previous suggestion that this band is due to C=O vibrational modes, we suggest
that the 6.0 $\mu$m feature arises from olefinic double-bond functional groups.
These groups are likely to be attached to aromatic rings which are responsible
for the major UIE bands. The possibility that the formation of these functional
groups is related to the hydrogenation process is discussed.


title:
Distinguishing finite group characters and refined local-global
  phenomena

abstract:
  Serre obtained a sharp bound on how often two irreducible degree $n$ complex
characters of a finite group can agree, which tells us how many local factors
determine an Artin $L$-function. We consider the more delicate question of
finding a sharp bound when these objects are primitive, and answer these
questions for $n=2,3$. This provides some insight on refined strong
multiplicity one phenomena for automorphic representations of GL$(n)$. For
general $n$, we also answer the character question for the families PSL$(2,q)$
and SL$(2,q)$.


title:
Nonequilibrium self-organization of colloidal particles on substrates:
  adsorption, relaxation, and annealing

abstract:
  Colloidal particles are considered ideal building blocks to produce materials
with enhanced physical properties. The state-of-the-art techniques for
synthesizing these particles provide control over shape, size, and
directionality of the interactions. In spite of these advances, there is still
a huge gap between the synthesis of individual components and the management of
their spontaneous organization towards the desired structures. The main
challenge is the control over the dynamics of self-organization. In their
kinetic route towards thermodynamically stable structures, colloidal particles
self-organize into intermediate (mesoscopic) structures that are much larger
than the individual particles and become the relevant units for the dynamics.
To follow the dynamics and identify kinetically trapped structures, one needs
to develop new theoretical and numerical tools. Here we discuss the
self-organization of functionalized colloids (also known as patchy colloids) on
attractive substrates. We review our recent results on the adsorption and
relaxation and explore the use of annealing cycles to overcome kinetic barriers
and drive the relaxation towards the targeted structures.


title: Universality of the ion flux to the JET outer wall

abstract:
  Universality in the ion flux to the JET outer-wall is observed in outerwall
limiter mounted Langmuir probe (OLP) time-series across a large range of plasma
current and line-averaged density during Ohmically heated horizontal target
L-mode plasmas. The mean, M, and the standard deviation, sigma, of the
ion-saturation current measured by the OLP show systematic variation with
plasma current and density. Both increase as either plasma current decreases
and/or density increases. Upon renormalization, achieved by subtraction of M
and rescaling by sigma, the probability distribution functions (PDFs) of each
signal collapse approximately onto a single curve. The shape of the curve
deviates from a distribution in the tail of the PDF and is better described by
a log-normal distribution. The collapse occurs over 4 decades of the ordinate
which, given the wide parameter space over which the data spans, is a strong
indication of universality.


title:
Cosmology without time: What to do with a possible signature change from
  quantum gravitational origin?

abstract:
  Within some approaches to loop quantum cosmology, the existence of an
Euclidean phase at high density has been suggested. In this article, we try to
explain clearly what are the observable consequences of this possible
disappearance of time. Depending on whether it is a real fundamental effect or
just an instability in the equation of motion, we show that very different
conclusions should be drawn. We finally mention some possible consequences of
this phenomenon in the black hole sector.


title:
Simultaneous Estimation of Noise Variance and Number of Peaks in
  Bayesian Spectral Deconvolution

abstract:
  The heuristic identification of peaks from noisy complex spectra often leads
to misunderstanding of the physical and chemical properties of matter. In this
paper, we propose a framework based on Bayesian inference, which enables us to
separate multipeak spectra into single peaks statistically and consists of two
steps. The first step is estimating both the noise variance and the number of
peaks as hyperparameters based on Bayes free energy, which generally is not
analytically tractable. The second step is fitting the parameters of each peak
function to the given spectrum by calculating the posterior density, which has
a problem of local minima and saddles since multipeak models are nonlinear and
hierarchical. Our framework enables the escape from local minima or saddles by
using the exchange Monte Carlo method and calculates Bayes free energy via the
multiple histogram method. We discuss a simulation demonstrating how efficient
our framework is and show that estimating both the noise variance and the
number of peaks prevents overfitting, overpenalizing, and misunderstanding the
precision of parameter estimation.


title: Caputo-Hadamard fractional derivatives of variable order

abstract:
  In this paper we present three types of Caputo-Hadamard derivatives of
variable fractional order, and study the relations between them. An
approximation formula for each fractional operator, using integer-order
derivatives only, is obtained, and an estimation for the error is given. At the
end we compare the exact fractional derivative of a concrete example with some
numerical approximations.


title: Glassy features of crystal plasticity

abstract:
  Crystal plasticity occurs by deformation bursts due to the avalanche-like
motion of dislocations. Here we perform extensive numerical simulations of a
three-dimensional dislocation dynamics model under quasistatic
stress-controlled loading. Our results show that avalanches are power-law
distributed, and display peculiar stress and sample size dependence: The
average avalanche size grows exponentially with the applied stress, and the
amount of slip increases with the system size. These results suggest that
intermittent deformation processes in crystalline materials exhibit an extended
critical-like phase in analogy to glassy systems, instead of originating from a
non-equilibrium phase transition critical point.


title:
On polynomially integrable planar outer billiards and curves with
  symmetry property

abstract:
  We show that every polynomially integrable planar outer convex billiard is
elliptic.


title:
Mass spectra and decays of ground and orbitally excited $c\bar{b}$
  states in non relativistic quark model

abstract:
  The complete spectrum of $c\bar{b}$ states is obtained in a phenomenological
non relativistic quark model(NRQM), which consists of a confinement potential
and one gluon exchange potential (OGEP) as effective quark - antiquark
potential. We make predictions for the radiative decay (E1 and M1) widths and
weak decay widths of $c\bar{b}$ states in the framework of NRQM formalism.


title: Exponential Disks from Stellar Scattering: III. Stochastic Models

abstract:
  Stellar scattering off irregularities in a galaxy disk has been shown to make
an exponential radial profile, but no fundamental reason for this has been
suggested. Here we show that exponentials are mathematically expected from
random scattering in a disk when there is a slight inward bias in the
scattering probability. Such a bias was present in our previous scattering
experiments that formed exponential profiles. Double exponentials can arise
when the bias varies with radius. This is a fundamental property of scattering
and may explain why piece-wise exponential profiles are ubiquitous in galaxies,
even after minor mergers and other disruptive events.


title:
Anions effects on the electronic structure and electrodynamic properties
  of the Mott insulator $\kappa$-(BEDT-TTF)$_2$Ag$_2$(CN)$_{3}$

abstract:
  The Mott insulator $\kappa$-(BEDT-TTF)$_2$Ag$_2$(CN)$_3$ forms a
highly-frustrated triangular lattice of $S=1/2$ dimers with a possible
quantum-spin-liquid state. Our experimental and numerical studies reveal the
emergence of a slight charge imbalance between crystallographically
inequivalent sites, relaxor dielectric response and hopping dc transport. In a
broader perspective we conclude that the universal properties of
strongly-correlated charge-transfer salts with spin liquid state are an
anion-supported valence band and cyanide-induced quasi-degenerate electronic
configurations in the relaxed state. The generic low-energy excitations are
caused by charged domain walls rather than by fluctuating electric dipoles.
They give rise to glassy dynamics characteristic of dimerized Mott insulators,
including the sibling compound $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$.


title: Cohomological vertex operators

abstract:
  Given a Calabi-Yau manifold and considering the $B$-branes on it as objects
in the derived category of coherent sheaves, we identify the vertex operators
for strings between two branes with elements of the cohomology groups of Ext
sheaves. We define the correlation functions for these general vertex
operators. Strings stretching between two coherent sheaves are studied as
homological extensions of the corresponding branes. In this context, we relate
strings between different pairs of branes when there are maps between these
branes. We also interpret some strings with ghost number $k$ as obstructions
for lifts or extensions of strings with ghost number $k-1$.


title: On Submodular Search and Machine Scheduling

abstract:
  Suppose some objects are hidden in a finite set $S$ of hiding places which
must be examined one-by-one. The cost of searching subsets of $S$ is given by a
submodular function and the probability that all objects are contained in a
subset is given by a supermodular function. We seek an ordering of $S$ that
finds all the objects in minimal expected cost. This problem is NP-hard and we
give an efficient combinatorial $2$-approximation algorithm, generalizing
analogous results in scheduling theory. We also give a new scheduling
application $1|prec|\sum w_A h(C_A)$, where a set of jobs must be ordered
subject to precedence constraints to minimize the weighted sum of some concave
function $h$ of the completion times of {\em subsets} of jobs. We go on to give
better approximations for submodular functions with low {\em total curvature}
and we give a full solution when the problem is what we call {\em
series-parallel decomposable}. Next, we consider a zero-sum game between a
cost-maximizing Hider and a cost-minimizing Searcher. We prove that the
equilibrium mixed strategies for the Hider are in the base polyhedron of the
cost function, suitably scaled, and we solve the game in the series-parallel
decomposable case, giving approximately optimal strategies in other cases.


title: Asymptotic property C of the wreath product ZwrZ

abstract:
  Using the relationship between transfinite asymptotic dimension and
asymptotic property C, we obtain that the wreath product Z wr Z has asymptotic
property C. Specifically, we prove that the transfinite asymptotic dimension of
the wreath product Z wr Z is no more than omega+ 1.


title: An introduction to computational algebraic statistics

abstract:
  In this paper, we introduce the fundamental notion of a Markov basis, which
is one of the first connections between commutative algebra and statistics. The
notion of a Markov basis is first introduced by Diaconis and Sturmfels (1998)
for conditional testing problems on contingency tables by Markov chain Monte
Carlo methods. In this method, we make use of a connected Markov chain over the
given conditional sample space to estimate the P-values numerically for various
conditional tests. A Markov basis plays an importance role in this arguments,
because it guarantees the connectivity of the chain, which is needed for
unbiasedness of the estimate, for arbitrary conditional sample space. As
another important point, a Markov basis is characterized as generators of the
well-specified toric ideals of polynomial rings. This connection between
commutative algebra and statistics is the main result of Diaconis and Sturmfels
(1998). After this first paper, a Markov basis is studied intensively by many
researchers both in commutative algebra and statistics, which yields an
attractive field called computational algebraic statistics. In this paper, we
give a review of the Markov chain Monte Carlo methods for contingency tables
and Markov bases, with some fundamental examples. We also give some
computational examples by algebraic software Macaulay2 and statistical software
R. Readers can also find theoretical details of the problems considered in this
paper and various results on the structure and examples of Markov bases in
Aoki, Hara and Takemura (2012).


title: Gravitational-wave tail effects to quartic non-linear order

abstract:
  Gravitational-wave tails are due to the backscattering of linear waves onto
the space-time curvature generated by the total mass of the matter source. The
dominant tails correspond to quadratic non-linear interactions and arise at the
one-and-a-half post-Newtonian (1.5PN) order in the gravitational waveform. The
"tails-of-tails", which are cubic non-linear effects appearing at the 3PN order
in the waveform, are also known. We derive here higher non-linear tail effects,
namely those associated with quartic non-linear interactions or
"tails-of-tails-of-tails", which are shown to arise at the 4.5PN order. As an
application, we obtain at that order the complete coefficient in the total
gravitational-wave energy flux of compact binary systems moving on circular
orbits. Our result perfectly agrees with black-hole perturbation calculations
in the limit of extreme mass ratio of the two compact objects.


title: OntoCat: Automatically categorizing knowledge in API Documentation

abstract:
  Most application development happens in the context of complex APIs;
reference documentation for APIs has grown tremendously in variety, complexity,
and volume, and can be difficult to navigate. There is a growing need to
develop well-organized ways to access the knowledge latent in the
documentation; several research efforts deal with the organization (ontology)
of API-related knowledge. Extensive knowledge-engineering work, supported by a
rigorous qualitative analysis, by Maalej & Robillard [3] has identified a
useful taxonomy of API knowledge. Based on this taxonomy, we introduce a domain
independent technique to extract the knowledge types from the given API
reference documentation. Our system, OntoCat, introduces total nine different
features and their semantic and statistical combinations to classify the
different knowledge types. We tested OntoCat on python API reference
documentation. Our experimental results show the effectiveness of the system
and opens the scope of probably related research areas (i.e., user behavior,
documentation quality, etc.).


title: Superconductivity in CaBi$_{2}$

abstract:
  Superconductivity is observed with critical temperature $T_{c}$ = 2.0 K in
self-flux-grown single crystals of $CaBi_{2}$. This material adopts the
$ZrSi_{2}$ structure type with lattice parameters a = 4.696(1) $\AA$, b =
7.081(2) $\AA$ and c = 4.611(1) $\AA$. The crystals of $CaBi_{2}$ were studied
by means of magnetic susceptibility, specific heat and electrical resistivity
measurements. The heat capacity jump at $T_{c}$ is $\Delta C/\gamma T_{c}$ =
1.41, confirming bulk superconductivity; the Sommerfeld coefficient $\gamma$ =
4.1 $mJ\: mol^{-1}\, K^{-2}$ and the Debye temperature $\Theta_{D}$ = 157 K.
The electron-phonon coupling strength is $\lambda_{el-ph}$ = 0.59, and the
thermodynamic critical field $H_{c}$ is low, between 111 and 124 Oe $CaBi_{2}$
is a moderate coupling type-I superconductor. Results of electronic structure
calculations are reported and charge densities, electronic bands, densities of
states and Fermi surfaces are discussed, focusing on the effects of
spin\textendash orbit coupling and electronic property anisotropy. We find a
mixed quasi-2D + 3D character in the electronic structure, which reflects the
layered crystal structure of the material.


title: Generic Feature Learning for Wireless Capsule Endoscopy Analysis

abstract:
  The interpretation and analysis of the wireless capsule endoscopy recording
is a complex task which requires sophisticated computer aided decision (CAD)
systems in order to help physicians with the video screening and, finally, with
the diagnosis. Most of the CAD systems in the capsule endoscopy share a common
system design, but use very different image and video representations. As a
result, each time a new clinical application of WCE appears, new CAD system has
to be designed from scratch. This characteristic makes the design of new CAD
systems a very time consuming. Therefore, in this paper we introduce a system
for small intestine motility characterization, based on Deep Convolutional
Neural Networks, which avoids the laborious step of designing specific features
for individual motility events. Experimental results show the superiority of
the learned features over alternative classifiers constructed by using state of
the art hand-crafted features. In particular, it reaches a mean classification
accuracy of 96% for six intestinal motility events, outperforming the other
classifiers by a large margin (a 14% relative performance increase).


title: Continuous-Variable Instantaneous Quantum Computing is hard to sample

abstract:
  Instantaneous quantum computing is a sub-universal quantum complexity class,
whose circuits have proven to be hard to simulate classically in the
Discrete-Variable (DV) realm. We extend this proof to the Continuous-Variable
(CV) domain by using squeezed states and homodyne detection, and by exploring
the properties of post-selected circuits. In order to treat post-selection in
CVs we consider finitely-resolved homodyne detectors, corresponding to a
realistic scheme based on discrete probability distributions of the measurement
outcomes. The unavoidable errors stemming from the use of finitely squeezed
states are suppressed through a qubit-into-oscillator GKP encoding of quantum
information, which was previously shown to enable fault-tolerant CV quantum
computation. Finally, we show that, in order to render post-selected
computational classes in CVs meaningful, a logarithmic scaling of the squeezing
parameter with the circuit size is necessary, translating into a polynomial
scaling of the input energy.


title:
Boundary Harnack principle for the absolute value of a one-dimensional
  subordinate Brownian motion killed at $0$

abstract:
  We prove the Harnack inequality and boundary Harnack principle for the
absolute value of a one-dimensional recurrent subordinate Brownian motion
killed upon hitting $0$, when $0$ is regular for itself and the Laplace
exponent of the subordinator satisfies certain global scaling conditions. Using
the conditional gauge theorem for symmetric Hunt processes we prove that the
Green function of this process killed outside of some interval $(a,b)$ is
comparable to the Green function of the corresponding killed subordinate
Brownian motion. We also consider several properties of the compensated
resolvent kernel $h$, which is harmonic for our process on $(0,1)$.


title:
Adaptive Nonnegative Matrix Factorization and Measure Comparisons for
  Recommender Systems

abstract:
  The Nonnegative Matrix Factorization (NMF) of the rating matrix has shown to
be an effective method to tackle the recommendation problem. In this paper we
propose new methods based on the NMF of the rating matrix and we compare them
with some classical algorithms such as the SVD and the regularized and
unregularized non-negative matrix factorization approach. In particular a new
algorithm is obtained changing adaptively the function to be minimized at each
step, realizing a sort of dynamic prior strategy. Another algorithm is obtained
modifying the function to be minimized in the NMF formulation by enforcing the
reconstruction of the unknown ratings toward a prior term. We then combine
different methods obtaining two mixed strategies which turn out to be very
effective in the reconstruction of missing observations. We perform a
thoughtful comparison of different methods on the basis of several evaluation
measures. We consider in particular rating, classification and ranking measures
showing that the algorithm obtaining the best score for a given measure is in
general the best also when different measures are considered, lowering the
interest in designing specific evaluation measures. The algorithms have been
tested on different datasets, in particular the 1M, and 10M MovieLens datasets
containing ratings on movies, the Jester dataset with ranting on jokes and
Amazon Fine Foods dataset with ratings on foods. The comparison of the
different algorithms, shows the good performance of methods employing both an
explicit and an implicit regularization scheme. Moreover we can get a boost by
mixed strategies combining a fast method with a more accurate one.


title:
Computational fluid dynamics modelling of left valvular heart diseases
  during atrial fibrillation

abstract:
  Although atrial fibrillation (AF), a common arrhythmia, frequently presents
in patients with underlying valvular disease, its hemodynamic contributions are
not fully understood. The present work aimed to computationally study how
physical conditions imposed by pathologic valvular anatomy act on AF
hemodynamics. We simulated AF with different severity grades of left-sided
valvular diseases and compared the cardiovascular effects that they exert
during AF, compared to lone AF. The fluid dynamics model used here has been
recently validated for lone AF and relies on a lumped parameterization of the
four heart chambers, together with the systemic and pulmonary circulation.
Three different grades of severity (mild, moderate, severe) were analyzed for
each of the four valvulopathies (aortic stenosis, mitral stenosis, aortic
regurgitation, mitral regurgitation). Regurgitation was hemodynamically more
relevant than stenosis, as the latter led to inefficient cardiac flow, while
the former introduced more drastic fluid dynamics variation. Moreover, mitral
valvulopathies were more significant than aortic ones. In case of aortic valve
diseases, proper mitral functioning damps out changes at atrial and pulmonary
levels. In the case of mitral valvulopathy, the mitral valve lost its
regulating capability, thus hemodynamic variations almost equally affected
regions upstream and downstream of the valve. The present study revealed that
both mitral and aortic regurgitation strongly affect hemodynamics, followed by
mitral stenosis, while aortic stenosis has the least impact among the analyzed
valvular diseases. The proposed approach can provide new mechanistic insights
as to which valvular pathologies merit more aggressive treatment of AF. Present
findings, if clinically confirmed, hold the potential to impact AF management
(e.g., adoption of a rhythm control strategy) in specific valvular diseases.


title: A simple multipurpose double-beam optical image analyzer

abstract:
  In the paper we present a low cost optical device which splits the light in
the focal plane into two separate optical paths and collimates it back into a
single image plane, and where a selective information processing ca be carried
out. The optical system is straightforward and easy implementable as it
consists of only three lens and two mirrors. The system is dedicated for
imaging in low-light-level conditions in which widely used optical devices,
based on beam-splitters or dichroic mirrors, suffer from light loss. We expose
examples of applications of our device, using a prototype model. The proposed
optical system may be employed for: monitoring the objects located in different
distances from observer (1), creating regions of different magnification within
a single image plane (2), high dynamic range photometry (3), or imaging in two
wavelength bands simultaneously (4).


title: Intrinsic potentials in locally harmonic manifolds

abstract:
  We consider the problem of allocating a finite number of heat sources in the
n-dimensional sphere. When only one such source -assumed to be of infinite
temperature- is placed and assuming a constant cooling rate in the sphere, we
prove that a (essentially) unique solution exists: the Constant Laplacian
potential (CL-potential). Actually, this potential can be defined intrinsically
in any CROSS (such as the real or complex projective spaces), providing a
natural alternative to Riesz's potentials in manifolds lacking a standard
isometric embedding into some Euclidean space. We describe an integral form of
the corresponding CL-energy for the case of the sphere and prove a relation of
minimizing configurations with separation distance and cap discrepancy. It
follows that minimal configurations for the Riesz energy are asymptotically
minimizing for the CL-energy.


title: Learning Null Space Projections in Operational Space Formulation

abstract:
  In recent years, a number of tools have become available that recover the
underlying control policy from constrained movements. However, few have
explicitly considered learning the constraints of the motion and ways to cope
with unknown environment. In this paper, we consider learning the null space
projection matrix of a kinematically constrained system in the absence of any
prior knowledge either on the underlying policy, the geometry, or
dimensionality of the constraints. Our evaluations have demonstrated the
effectiveness of the proposed approach on problems of differing dimensionality,
and with different degrees of non-linearity.


title:
Beam performance and instrumentation studies for the ProtoDUNE-DP
  experiment of CENF

abstract:
  In this note, we address the beam performance (particle content, rates) with
emphasis on the momentum determination and particle identification methods for
the new H2-VLE (Very Low Energy) beam line that will serve the double phase
ProtoDUNE experiment (also known as WA105), in the framework of the CENF
project. The proposed instrumentation is configured to achieve an optimal
pi/K/proton separation over the full spectrum of provided beam energies, from
0.4 GeV up to 12 GeV, as well as precise momentum measurement to a percent
level, if required by the experiment. This note focuses on the H2-VLE beam line
for the Double Phase ProtoDUNE experiment, however the same approach can be
implemented for the H4-VLE beam, since the design of the two beam lines is very
similar.


title: Spatial Goos-H\"anchen shift in photonic graphene

abstract:
  We present a theoretical study of the spatial Goos-H\"anchen shift occurring
at the interface between two different photonic graphene lattices. Numerical
simulations of light propagation in such a wave guiding system are also
presented to corroborate our findings.


title: Semantic Clustering for Robust Fine-Grained Scene Recognition

abstract:
  In domain generalization, the knowledge learnt from one or multiple source
domains is transferred to an unseen target domain. In this work, we propose a
novel domain generalization approach for fine-grained scene recognition. We
first propose a semantic scene descriptor that jointly captures the subtle
differences between fine-grained scenes, while being robust to varying object
configurations across domains. We model the occurrence patterns of objects in
scenes, capturing the informativeness and discriminability of each object for
each scene. We then transform such occurrences into scene probabilities for
each scene image. Second, we argue that scene images belong to hidden semantic
topics that can be discovered by clustering our semantic descriptors. To
evaluate the proposed method, we propose a new fine-grained scene dataset in
cross-domain settings. Extensive experiments on the proposed dataset and three
benchmark scene datasets show the effectiveness of the proposed approach for
fine-grained scene transfer, where we outperform state-of-the-art scene
recognition and domain generalization methods.


title: Testing 5d-6d dualities with fractional D-branes

abstract:
  6d SCFTs compactified on a circle can often be studied from nonperturbative
5d super-Yang-Mills theories, using instanton solitons. However, the 5d
Yang-Mills theories with 6d UV fixed points frequently have too many
hypermultiplet matters, which makes it difficult to use the ADHM techniques for
instantons. With the examples of 6d $\mathcal{N}=(1,0)$ SCFTs with $Sp(N)$
gauge symmetry and $2N+8$ fundamental hypermultiplets, we show that one can
still make rigorous studies of these 5d-6d relations in the `fractional D-brane
sectors'. We test the recently proposed 5d duals given by $Sp(N+1)$ gauge
theories, and compare their instanton partition functions with the elliptic
genera of 6d self-dual strings.


title: Neutrinophilic Non-Standard Interactions

abstract:
  We construct UV-complete models for non-standard neutrino interactions
mediated by a sub-GeV gauge boson Z' coupled to baryon number $B$ or $B-L$. A
flavor-dependent Z' coupling to neutrinos is induced by mixing a U(1)'-charged
Dirac fermion with the active neutrinos, naturally suppressing flavor violation
or non-universality of the charged leptons to the loop level. We show that
these models can give rise to large flavor-conserving as well as
flavor-violating non-standard neutral-current neutrino interactions potentially
observable in current or future oscillation experiments such as DUNE without
being in conflict with other constraints such as neutrino scattering or
lepton-flavor-violating decays. In particular, the LMA-Dark solution to the
solar-neutrino anomaly can be obtained for $U(1)_B$, but not for $U(1)_{B-L}$.


title:
New porous water ice metastable at atmospheric pressure obtained by
  emptying a hydrogen filled ice

abstract:
  The properties of some forms of water ice reserve still intriguing surprises.
Besides the several stable or metastable phases of pure ice, solid mixtures of
water with gases are precursors of other ices, since in some cases they may be
emptied, leaving a metastable hydrogen bound water structure. We present here
the first characterization of a new form of ice, obtained from the crystalline
solid compound of water and molecular hydrogen called C$_0$ filled ice. By
means of Raman spectroscopy, we measure the hydrogen release at different
temperatures, and succeed in rapidly removing all the hydrogen molecules,
obtaining a new form of ice (ice XVII). Its structure is determined by means of
neutron diffraction measurements. Of paramount interest is that the emptied
crystal can adsorb again hydrogen and release it repeatedly, showing a
temperature dependent hysteresis.


title: On the topology of arrangements of a cubic and its inflectional tangents

abstract:
  A $k$-Artal arrangement is a reducible algebraic curve composed of a smooth
cubic and $k$ inflectional tangents. By studying the topological properties of
their subarrangements, we prove that for $k=3,4,5,6$, there exist Zariski pairs
of $k$-Artal arrangements. These Zariki pairs can be distinguished in a
geometric way by the number of collinear triples in the set of singular points
contained in the cubic.


title:
MOCCA-SURVEY database I. Accreting white dwarf binary systems in
  globular clusters -- I. cataclysmic variables -- present-day population

abstract:
  In this paper, which is the first in a series of papers associated with
cataclysmic variables and related objects, we introduce the CATUABA code, a
numerical machinery written for analysis of the MOCCA simulations, and show
some first results by investigating the present-day population of cataclysmic
variables in globular clusters. Emphasis was given on their properties and the
observational selection effects when observing and detecting them. In this work
we analysed in this work six models, including three with Kroupa distributions
of the initial binaries. We found that for models with Kroupa initial
distributions, considering the standard value of the efficiency of the common
envelope phase adopted in BSE, no single cataclysmic variable was formed only
via binary stellar evolution, i. e., in order to form them, strong dynamical
interactions have to take place. We show and explain why this is inconsistent
with observational and theoretical results. Our results indicate that the
population of cataclysmic variables in globular clusters is, mainly, in the
last stage of their evolution and observational selection effects can
drastically change the expected number of observed cataclysmic variables. We
show that the probability of observing them during the outbursts is extremely
small and conclude that the best way of looking for cataclysmic variables in
globular clusters is by searching for variabilities during quiescence, instead
of during outbursts. For that, one would need a very deep observation which
could reach magnitudes $\gtrsim$ 27 mag. Finally, we argue that cataclysmic
variables in globular clusters are not necessarily magnetic.


title:
Mode Modification of Plasmonic Gap Resonances induced by Strong Coupling
  with Molecular Excitons

abstract:
  Plasmonic cavities can be used to control the atom-photon coupling process at
the nanoscale, since they provide ultrahigh density of optical states in an
exceptionally small mode volume. Here we demonstrate strong coupling between
molecular excitons and plasmonic resonances (so-called plexcitonic coupling) in
a film-coupled nanocube cavity, which can induce profound and significant
spectral and spatial modifications to the plasmonic gap modes. Within the
spectral span of a single gap mode in the nanotube-film cavity with a 3-nm wide
gap, the introduction of narrow-band J-aggregate dye molecules not only enables
an anti-crossing behavior in the spectral response, but also splits the single
spatial mode into two distinct modes that are easily identified by their
far-field scattering profiles. Simulation results confirm the experimental
findings and the sensitivity of the plexcitonic coupling is explored using
digital control of the gap spacing. Our work opens up a new perspective to
study the strong coupling process, greatly extending the functionality of
nanophotonic systems, with the potential to be applied in cavity quantum
electrodynamic systems.


title: Massive vectors and loop observables: the $g-2$ case

abstract:
  We discuss the use of massive vectors for the interpretation of some recent
experimental anomalies, with special attention to the muon $g-2$. We restrict
our discussion to the case where the massive vector is embedded into a
spontaneously broken gauge symmetry, so that the predictions are not affected
by the choice of an arbitrary energy cut-off. Extended gauge symmetries,
however, typically impose strong constraints on the mass of the new vector
boson and for the muon $g-2$ they basically rule out, barring the case of
abelian gauge extensions, the explanation of the discrepancy in terms of a
single vector extension of the standard model. We finally comment on the use of
massive vectors for $B$-meson decay and di-photon anomalies.


title:
Wannier-Bloch approach to localization in high harmonics generation in
  solids

abstract:
  Emission of high-order harmonics from solids provides a new avenue in
attosecond science. On one hand, it allows to investigate fundamental processes
of the non-linear response of electrons driven by a strong laser pulse in a
periodic crystal lattice. On the other hand, it opens new paths toward
efficient attosecond pulse generation, novel imaging of electronic wave
functions, and enhancement of high-order harmonic generation (HHG) intensity. A
key feature of HHG in a solid (as compared to the well-understood phenomena of
HHG in an atomic gas) is the delocalization of the process, whereby an electron
ionized from one site in the periodic lattice may recombine with any other.
Here, we develop an analytic model, based on the localized Wannier wave
functions in the valence band and delocalized Bloch functions in the conduction
band. This Wannier-Bloch approach assesses the contributions of individual
lattice sites to the HHG process, and hence addresses precisely the question of
localization of harmonic emission in solids. We apply this model to investigate
HHG in a ZnO crystal for two different orientations, corresponding to wider and
narrower valence and conduction bands, respectively. Interestingly, for
narrower bands, the HHG process shows significant localization, similar to
harmonic generation in atoms. For all cases, the delocalized contributions to
HHG emission are highest near the band-gap energy. Our results pave the way to
controlling localized contributions to HHG in a solid crystal, with hard to
overestimate implications for the emerging area of atto-nanoscience.

categories: cond-mat.mes-hall physics.atom-ph physics.optics quant-ph


title: Possible discovery channel for fourth chiral family up-quark at the LHC

abstract:
  Resonant production of fourth chiral family up quark at the LHC via anomalous
interactions have been analyzed. It is shown that search for resonances in
W^{+}b final states could lead to discovery of the fourth chiral family and
simultaneously determine scale of the new physics, presumabely related to the
quark and lepton compositeness. Obtained results emphasize an importance of
W-leading jet invariant mass analysis in search for W+jets final states at the
LHC, both with and without b-tagging.


title:
PASSATA - Object oriented numerical simulation software for adaptive
  optics

abstract:
  We present the last version of the PyrAmid Simulator Software for Adaptive
opTics Arcetri (PASSATA), an IDL and CUDA based object oriented software
developed in the Adaptive Optics group of the Arcetri observatory for
Monte-Carlo end-to-end adaptive optics simulations. The original aim of this
software was to evaluate the performance of a single conjugate adaptive optics
system for ground based telescope with a pyramid wavefront sensor. After some
years of development, the current version of PASSATA is able to simulate
several adaptive optics systems: single conjugate, multi conjugate and ground
layer, with Shack Hartmann and Pyramid wavefront sensors. It can simulate from
8m to 40m class telescopes, with diffraction limited and resolved sources at
finite or infinite distance from the pupil. The main advantages of this
software are the versatility given by the object oriented approach and the
speed given by the CUDA implementation of the most computational demanding
routines. We describe the software with its last developments and present some
examples of application.


title:
Multiple Quantum Hypothesis Testing Expressions and Classical-Quantum
  Channel Converse Bounds

abstract:
  Alternative exact expressions are derived for the minimum error probability
of a hypothesis test discriminating among $M$ quantum states. The first
expression corresponds to the error probability of a binary hypothesis test
with certain parameters; the second involves the optimization of a given
information-spectrum measure. Particularized in the classical-quantum channel
coding setting, this characterization implies the tightness of two existing
converse bounds; one derived by Matthews and Wehner using hypothesis-testing,
and one obtained by Hayashi and Nagaoka via an information-spectrum approach.


title: The prevalence of star formation as a function of Galactocentric radius

abstract:
  We present large-scale trends in the distribution of star-forming objects
revealed by the Hi-GAL survey. As a simple metric probing the prevalence of
star formation in Hi-GAL sources, we define the fraction of the total number of
Hi-GAL sources with a 70-micron counterpart as the "star-forming fraction" or
SFF. The mean SFF in the inner galactic disc (3.1 kpc < R_GC < 8.6 kpc) is 25%.
Despite an apparent pile-up of source numbers at radii associated with spiral
arms, the SFF shows no significant deviations at these radii, indicating that
the arms do not affect the star-forming productivity of dense clumps either via
physical triggering processes or through the statistical effects of larger
source samples associated with the arms. Within this range of Galactocentric
radii, we find that the SFF declines with R_GC at a rate of -0.026 +/- 0.002
per kiloparsec, despite the dense gas mass fraction having been observed to be
constant in the inner Galaxy. This suggests that the SFF may be weakly
dependent on one or more large-scale physical properties of the Galaxy, such as
metallicity, radiation field, pressure or shear, such that the dense
sub-structures of molecular clouds acquire some internal properties inherited
from their environment.


title:
Measurement of top quark polarization in $t \overline{t}$ lepton+jets
  final states

abstract:
  We present a study of top quark polarization in $t \overline{t}$ events
produced in $p \overline{p}$ collisions at $\sqrt{s}=1.96$ TeV. Data correspond
to 9.7 fb$^{-1}$ collected with the D0 detector at the Tevatron. We use final
states containing a lepton and at least three jets. The polarization is
measured using the distribution of leptons along the beam and helicity axes,
and the axis normal to the production plane. This is the first measurement of
top quark polarization at the Tevatron in $\ell$+jets final states, and first
measurement of transverse polarization in $t \overline{t}$ production. The
observed distributions are consistent with the standard model.


title:
Contamination of the Epoch of Reionization power spectrum in the
  presence of foregrounds

abstract:
  We construct foreground simulations comprising spatially correlated
extragalactic and diffuse Galactic emission components and calculate the
`intrinsic' (instrument-free) two-dimensional spatial power spectrum and the
cylindrically and spherically averaged three-dimensional k-space power spectra
of the Epoch of Reionization (EoR) and our foreground simulations using a
Bayesian power spectral estimation framework. This leads us to identify a model
dependent region of optimal signal estimation for our foreground and EoR
models, within which the spatial power in the EoR signal relative to
foregrounds is maximised. We identify a target field dependent region, in
k-space, of intrinsic foreground power spectral contamination at low k_perp and
k_parallel and a transition to a relatively foreground-free intrinsic EoR
window in the complement to this region. The contaminated region of k-space
demonstrates that simultaneous estimation of the EoR and foregrounds is
important for obtaining statistically robust estimates of the EoR power
spectrum; biased results will be obtained from methodologies that ignore their
covariance. Using simulated observations with frequency dependent uv-coverage
and primary beam, with the former derived for HERA in 37-antenna and
331-antenna configuration, we recover instrumental power spectra consistent
with their intrinsic counterparts. We discuss the implications of these results
for optimal strategies for unbiased estimation of the EoR power spectrum.


title: Symbolic powers of ideals and their topology over a module

abstract:
  Let $I$ denote an ideal of a Noetherian ring $R$ and $N$ a non-zero finitely
generated $R$-module. In the present paper, some necessary and sufficient
conditions are given to determine when the $I$-adic topology on $N$ is
equivalent to the $I$-symbolic topology on $N$. Among other things, we shall
give a complete solution to the question raised by R. Hartshorne in [{\it
Affine duality and cofiniteness}, Invent. Math. {\bf9}(1970), 145-164], for a
prime ideal $\frak p$ of dimension one in a local Noetherian ring $R$, by
showing that the $\frak{p}$-adic topology on $N$ is equivalent to the
$\frak{p}$-symbolic topology on $N$ if and only if for all $z\in \Ass_{R^*}N^*$
there exists $\frak{q}\in \Supp(N^*)$ such that $z\subseteq \frak{q}$ and
$\frak{q}\cap R=\frak{p}.$ Also, it is shown that if for every
${\mathfrak{p}}\in \Supp(N)$ with $\dim R/\mathfrak{p}=1$, the
$\mathfrak{p}$-adic and the $\mathfrak{p}$-symbolic topologies are equivalent
on $N$, then $N$ is unmixed and $\Ass_{R} N$ has only one element. Finally, we
show that if $\Ass_{R_{\mathfrak{p}}^*}{N^*_{\mathfrak{p}}}$ consists of a
single prime ideal, for all ${\mathfrak{p}}\in {A^*}(I,N)$, then the $I$-adic
and the $I$-symbolic topologies on $N$ are equivalent. \end{abstract}


title: Grounded Lexicon Acquisition - Case Studies in Spatial Language

abstract:
  This paper discusses grounded acquisition experiments of increasing
complexity. Humanoid robots acquire English spatial lexicons from robot tutors.
We identify how various spatial language systems, such as projective, absolute
and proximal can be learned. The proposed learning mechanisms do not rely on
direct meaning transfer or direct access to world models of interlocutors.
Finally, we show how multiple systems can be acquired at the same time.


title: Unrelated Machine Scheduling of Jobs with Uniform Smith Ratios

abstract:
  We consider the classic problem of scheduling jobs on unrelated machines so
as to minimize the weighted sum of completion times. Recently, for a small
constant $\varepsilon >0 $, Bansal et al. gave a
$(3/2-\varepsilon)$-approximation algorithm improving upon the natural barrier
of $3/2$ which follows from independent randomized rounding. In simplified
terms, their result is obtained by an enhancement of independent randomized
rounding via strong negative correlation properties.
  In this work, we take a different approach and propose to use the same
elegant rounding scheme for the weighted completion time objective as devised
by Shmoys and Tardos for optimizing a linear function subject to makespan
constraints. Our main result is a $1.21$-approximation algorithm for the
natural special case where the weight of a job is proportional to its
processing time (specifically, all jobs have the same Smith ratio), which
expresses the notion that each unit of work has the same weight. In addition,
as a direct consequence of the rounding, our algorithm also achieves a
bi-criteria $2$-approximation for the makespan objective. Our technical
contribution is a tight analysis of the expected cost of the solution compared
to the one given by the Configuration-LP relaxation - we reduce this task to
that of understanding certain worst-case instances which are simple to analyze.


title:
Cataclysmic variables in Globular clusters: First results on the
  analysis of the MOCCA simulations database

abstract:
  In this first investigation of the MOCCA database with respect to cataclysmic
variables, we found that for models with Kroupa initial distributions,
considering the standard value of the efficiency of the common-envelope phase
adopted in BSE, no single cataclysmic variable was formed only via binary
stellar evolution, i. e., in order to form them, strong dynamical interactions
have to take place. Our results also indicate that the population of
cataclysmic variables in globular clusters are, mainly, in the last stage of
their evolution and observational selection effects can change drastically the
expected number and properties of observed cataclysmic variables.


title:
Finite dual of a cocommutative Hopf algebroid. Application to linear
  differential matrix equations and Picard-Vessiot theory

abstract:
  A fundamental tool of Differential Galois Theory is the assignment of an
algebraic group to each finite-dimensional differential module over
differential field in such a way that the category of differential modules it
generates is equivalent, as a symmetric monoidal category, to the category of
representations of the group. Its underlying set is then recognized as the
group of differential automorphisms of the Picard-Vessiot field extension of
the base field for this differential module. These results can be obtained by
means of a Tannaka reconstruction process, applied to the abelian category of
finite-dimensional differential modules. In this paper, we explore the
possibility of extending this theory when the differential field is replaced by
a more general differential ring $A$. In this case, it is reasonable to deal
with differential modules which are finitely generated and projective over $A$.
A major obstacle is that this category is not abelian, in contrast with the
classical case when $A$ is a field. To overcome this difficulty, we develop
some fundamental results concerning the \emph{finite dual}, hereby introduced,
of a cocommutative Hopf algebroid, and a canonical monoidal functor sending
(differential) modules to comodules. This functor is proved to be an
equivalence of categories whenever a canonical ring homomorphism, which is
introduced in this work, with domain in the aforementioned finite dual and with
values in the convolutional ring, is injective. Module-theoretical sufficient
conditions to get its injectivity are investigated. This machinery is applied
to differential modules and their Picard-Vessiot theory.


title: Note on linearly equivalent ideal topologies over Noetherian modules

abstract:
  Let $R$ be a commutative Noetherian ring, and let $N$ be a non-zero finitely
generated $R$-module. In this paper, the main result asserts that for any
$N$-proper ideal $\frak a$ of $R,$ the $\frak a$-symbolic topology on $N$ is
linearly equivalent to the $\frak a$-adic topology on $N$ if and only if, for
every $\frak p\in \Supp(N)$, $\Ass_{R_{\mathfrak {p} }}N_{\mathfrak {p}}$
consists of a single prime ideal and $\dim N\leq 1$.


title: Current distributions in stripe Majorana junctions

abstract:
  We calculate current and density distributions in stripe (2D planar)
junctions between normal and Majorana nanowires having a finite ($y$)
transverse length. In presence of a magnetic field with vertical and in-plane
components, the $y$-symmetry of the charge current distribution in the normal
lead changes strongly across the Majorana phase transition: from
center-symmetric if a Majorana mode is present to laterally-shifted (as
expected by the Hall effect) if the field is tilted such as to destroy the
Majorana mode due to the projection rule. We compare quasi-particle and charge
distributions of current and density, as well as spin magnetizations. The
Majorana mode causes opposite spin accumulations on the junction and the
emergence of a spin current.


title: Asymptotics for the Time of Ruin in the War of Attrition

abstract:
  We consider two players, starting with $m$ and $n$ units, respectively. In
each round, the winner is decided with probability proportional to each
player's fortune, and the opponent loses one unit. We prove an explicit formula
for the probability $p(m,n)$ that the first player wins. When $m\sim Nx_{0}$,
$n\sim N y_{0}$, we prove the fluid limit as $N\to \infty$. When $x_{0}=y_{0}$,
then $z\to p(N,N+z\sqrt{N})$ converges to the standard normal CDF and the
difference in fortunes scales diffusively. The exact limit of the time of ruin
$\tau_{N}$ is established as $(T-\tau_N) \sim N^{-\beta}W^{\frac{1}{\beta}}$,
$\beta=\frac{1}{4}$, $T=x_{0}+y_{0}$. Modulo a constant, $W \sim
\chi^{2}_{1}(z_{0}^{2}/T^{2})$.


title: Night-sky brightness and extinction at Mt. Shatdzhatmaz

abstract:
  The photometric sky quality of Mt. Shatdzhatmaz, the site of Sternberg
Astronomical Institute Caucasian Observatory 2.5 m telescope, is characterized
here by the statistics of the night-time sky brightness and extinction. The
data were obtained as a by-product of atmospheric optical turbulence
measurements with the MASS (Multi-Aperture Scintillation Sensor) device
conducted in 2007--2013. The factors biasing night-sky brightness measurements
are considered and a technique to reduce their impact on the statistics is
proposed.
  The single-band photometric estimations provided by MASS are easy to
transform to the standard photometric bands. The median moonless night-sky
brightness is 22.1, 21.1, 20.3, and 19.0 mag per square arcsec for the $B$,
$V$, $R$, and $I$ spectral bands, respectively. The median extinction
coefficients for the same photometric bands are 0.28, 0.17, 0.13, and 0.09 mag.
The best atmospheric transparency is observed in winter.


title: Strong dynamics, composite Higgs and the conformal window

abstract:
  We review recent progress in the lattice investigations of near-conformal
non-abelian gauge theories relevant for dynamical symmetry breaking and model
building of composite Higgs models. The emphasis is placed on the mass spectrum
and the running renormalized coupling. The role of a light composite scalar
isosinglet particle as a composite Higgs particle is highlighted.


title: Scale Invariant Interest Points with Shearlets

abstract:
  Shearlets are a relatively new directional multi-scale framework for signal
analysis, which have been shown effective to enhance signal discontinuities
such as edges and corners at multiple scales. In this work we address the
problem of detecting and describing blob-like features in the shearlets
framework. We derive a measure which is very effective for blob detection and
closely related to the Laplacian of Gaussian. We demonstrate the measure
satisfies the perfect scale invariance property in the continuous case. In the
discrete setting, we derive algorithms for blob detection and keypoint
description. Finally, we provide qualitative justifications of our findings as
well as a quantitative evaluation on benchmark data. We also report an
experimental evidence that our method is very suitable to deal with compressed
and noisy images, thanks to the sparsity property of shearlets.


title:
Effective Hamiltonian for surface states of topological insulator
  nanotubes

abstract:
  In this work we derive an effective Hamiltonian for the surface states of a
hollow topological insulator (TI) nanotube with finite width walls. Unlike a
solid TI cylinder, a TI nanotube possesses both an inner as well as outer
surface on which the states localized at each surface are coupled together. The
curvature along the circumference of the nanotube leads to a spatial variation
of the spin orbit interaction field experienced by the charge carriers as well
as an asymmetry between the inner and outer surfaces of the nanotube. Both of
these features result in terms in the effective Hamiltonian for a TI nanotube
absent in that of a flat TI thin film of the same thickness. We calculate the
numerical values of the parameters for a \ce{Bi2Se3} nanotube as a function of
the inner and outer radius, and show that the differing relative magnitudes
between the parameters result in qualitatively differing behaviour for the
eigenstates of tubes of different dimensions.


title: A Characterization of locally quasi-unmixed rings

abstract:
  Let $\bar{I}$ denote the integral closure of an ideal in a Noetherian ring
$R$. The main result of this paper asserts that $R$ is locally quasi-unmixed if
and only if, the topologies defined by $\overline{I^n}$ and $I^{\langle
n\rangle}$, $\ n\geq 1$, are equivalent. In addition, some results about the
behavior of linearly equivalent topologies of ideals under various ring
homomorphisms are included.


title:
Corrugated structure insertion for extending the SASE bandwidth up to 3%
  at the European XFEL

abstract:
  The usage of x-ray free electron laser (XFEL) in femtosecond
nanocrystallography involves sequential illumination of many small crystals of
arbitrary orientation. Hence a wide radiation bandwidth will be useful in order
to obtain and to index a larger number of Bragg peaks used for determination of
the crystal orientation. Considering the baseline configuration of the European
XFEL in Hamburg, and based on beam dynamics simulations, we demonstrate here
that the usage of corrugated structures allows for a considerable increase in
radiation bandwidth. Data collection with a 3% bandwidth, a few microjoule
radiation pulse energy, a few femtosecond pulse duration, and a photon energy
of 5.4 keV is possible. For this study we have developed an analytical modal
representation of the short-range wake function of the flat corrugated
structures for arbitrary offsets of the source and the witness particles.