title:
A linear scaling method to evaluate the ion-electron potential of
  crystalline solids

abstract:
  We propose a simple linear scaling expression in reciprocal space for
evaluating the ion--electron potential of crystalline solids. The expression
replaces the long-range ion--electron potential with an equivalent localized
charge distribution and corresponding boundary conditions on the unit cell.
Given that no quadratic scaling structure factor is required---as used in
traditional methods---the expression shows inherent linear behavior, and is
well suited to simulating large-scale systems within orbital-free density
functional theory. The scheme is implemented in the ATLAS software package and
benchmarked by using a solid Mg bcc lattice containing tens of thousands of
atoms in the unit cell. The test results show that the method can efficiently
model large crystals with high computational accuracy.


title: Bioinformatics and Classical Literary Study

abstract:
  This paper describes the Quantitative Criticism Lab, a collaborative
initiative between classicists, quantitative biologists, and computer
scientists to apply ideas and methods drawn from the sciences to the study of
literature. A core goal of the project is the use of computational biology,
natural language processing, and machine learning techniques to investigate
authorial style, intertextuality, and related phenomena of literary
significance. As a case study in our approach, here we review the use of
sequence alignment, a common technique in genomics and computational
linguistics, to detect intertextuality in Latin literature. Sequence alignment
is distinguished by its ability to find inexact verbal similarities, which
makes it ideal for identifying phonetic echoes in large corpora of Latin texts.
Although especially suited to Latin, sequence alignment in principle can be
extended to many other languages.


title:
Dot-Product Join: An Array-Relation Join Operator for Big Model
  Analytics

abstract:
  Big Model analytics tackles the training of massive models that go beyond the
available memory of a single computing device, e.g., CPU or GPU. It generalizes
Big Data analytics which is targeted at how to train memory-resident models
over out-of-memory training data. In this paper, we propose an in-database
solution for Big Model analytics. We identify dot-product as the primary
operation for training generalized linear models and introduce the first
array-relation dot-product join database operator between a set of sparse
arrays and a dense relation. This is a constrained formulation of the
extensively studied sparse matrix vector multiplication (SpMV) kernel. The
paramount challenge in designing the dot-product join operator is how to
optimally schedule access to the dense relation based on the non-contiguous
entries in the sparse arrays. We prove that this problem is NP-hard and propose
a practical solution characterized by two technical contributions---dynamic
batch processing and array reordering. We devise three heuristics -- LSH,
Radix, and K-center -- for array reordering and analyze them thoroughly. We
execute extensive experiments over synthetic and real data that confirm the
minimal overhead the operator incurs when sufficient memory is available and
the graceful degradation it suffers as memory becomes scarce. Moreover,
dot-product join achieves an order of magnitude reduction in execution time
over alternative in-database solutions.


title:
The new neutron grating interferometer at the ANTARES beamline - Design,
  Principle, and Applications -

abstract:
  Neutron grating interferometry is an advanced method in neutron imaging that
allows the simultaneous recording of the transmission, the differential phase
and the dark-field image. Especially the latter has recently received high
interest because of its unique contrast mechanism which marks ultra-small-angle
neutron scattering within the sample. Hence, in neutron grating interferometry,
an imaging contrast is generated by scattering of neutrons off micrometer-sized
inhomogeneities. Although the scatterer cannot be resolved it leads to a
measurable local decoherence of the beam. Here, a report is given on the design
considerations, principles and applications of a new neutron grating
interferometer which has recently been implemented at the ANTARES beamline at
the Heinz Maier-Leibnitz Zentrum. Its highly flexible design allows to perform
experiments such as directional and quantitative dark-field imaging which
provide spatially resolved information on the anisotropy and shape of the
microstructure of the sample. A comprehensive overview of the nGI principle is
given, followed by theoretical considerations to optimize the setup performance
for different applications. Furthermore, an extensive characterization of the
setup is presented and its abilities are demonstrated on selected case studies:
(i) dark-field imaging for material differentiation, (ii) directional
dark-field imaging to mark and quantify micrometer anisotropies within the
sample and (iii) quantitative dark-field imaging, providing additional size
information on the sample's microstructure by probing its autocorrelation
function.


title:
Distributed multi-frequency image reconstruction for
  radio-interferometry

abstract:
  The advent of enhanced technologies in radio interferometry and the
perspective of the SKA telescope bring new challenges in image reconstruction.
One of these challenges is the spatio-spectral reconstruction of large
(Terabytes) data cubes with high fidelity. This contribution proposes an
alternative implementation of one such 3D prototype algorithm, MUFFIN
(MUlti-Frequency image reconstruction For radio INterferometry), which combines
spatial and spectral analysis priors. Using a recently proposed primal dual
algorithm, this new version of MUFFIN allows a parallel implementation where
computationally intensive steps are split by spectral channels. This
parallelization allows to implement computationally demanding translation
invariant wavelet transforms (IUWT), as opposed to the union of bases used
previously. This alternative implementation is important as it opens the
possibility of comparing these efficient dictionaries, and others, in
spatio-spectral reconstruction. Numerical results show that the IUWT-based
version can be successfully implemented at large scale with performances
comparable to union of bases.


title: Offshell thermodynamic metrics of the Schwarzschild black hole

abstract:
  Thermodynamic metric usually works only for those black holes with more than
one conserved charge, therefore the Schwarzschild black hole was excluded. In
this letter, we compute and compare different versions of offshell
thermodynamic metric for the Schwarzschild-like black hole by introducing a new
degree of freedom. This new degree of freedom could be the running Newton
constant, a cutoff scale for regular black hole, a noncommutative deformation,
or the deformed parameter in the nonextensive Tsallis-Renyi entropy. The
onshell metric of the deformed Schwarzschild solution would correspond to the
submanifold by gauge fixing of this additional degree of freedom. In
particular, the thermal Ricci scalar for the Schwarzschild black hole, though
different for various deformation, could be obtained by switching off the
deformation.


title:
Flexible online multivariate regression with variational Bayes and the
  matrix-variate Dirichlet process

abstract:
  Flexible regression methods where interest centres on the way that the whole
distribution of a response vector changes with covariates are very useful in
some applications. A recently developed technique in this regard uses the
matrix-variate Dirichlet process as a prior for a mixing distribution on a
coefficient in a multivariate linear regression model. The method is
attractive, particularly in the multivariate setting, for the convenient way
that it allows for borrowing strength across different component regressions
and for its computational simplicity and tractability. The purpose of the
present article is to develop fast online variational Bayes approaches to
fitting this model and to investigate how they perform compared to MCMC and
batch variational methods in a number of scenarios.


title: Spectrality and tiling by cylindric domains

abstract:
  A bounded set $\Omega \subset \mathbb{R}^d$ is called a spectral set if the
space $L^2(\Omega)$ admits a complete orthogonal system of exponential
functions. We prove that a cylindric set $\Omega$ is spectral if and only if
its base is a spectral set. A similar characterization is obtained of the
cylindric sets which can tile the space by translations.


title:
Noise thermometry applied to thermoelectric measurements in InAs
  nanowires

abstract:
  We apply noise thermometry to characterize charge and thermoelectric
transport in single InAs nanowires (NWs) at a bath temperature of 4.2 K. Shot
noise measurements identify elastic diffusive transport in our NWs with
negligible electron-phonon interaction. This enables us to set up a measurement
of the diffusion thermopower. Unlike in previous approaches, we make use of a
primary electronic noise thermometry to calibrate a thermal bias across the NW.
In particular, this enables us to apply a contact heating scheme, which is much
more efficient in creating the thermal bias as compared to conventional
substrate heating. The measured thermoelectric Seebeck coefficient exhibits
strong mesoscopic fluctuations in dependence on the back-gate voltage that is
used to tune the NW carrier density. We analyze the transport and
thermoelectric data in terms of approximate Mott's thermopower relation and to
evaluate a gate-voltage to Fermi energy conversion factor.


title: Antikaon-nucleon interaction and Lambda(1405) in chiral SU(3) dynamics

abstract:
  The properties of the Lambda(1405) resonance are key ingredients for
determining the antikaon-nucleon interaction in strangeness nuclear physics,
and the novel internal structure of the Lambda(1405) is of great interest in
hadron physics, as a prototype case of a baryon that does not fit into the
simple three-quark picture. We show that a quantitative description of the
antikaon-nucleon interaction with the Lambda(1405) is achieved in the framework
of chiral SU(3) dynamics, with the help of recent experimental progress.
Further constraints on the Kbar N subthreshold interaction are provided by
analyzing pi Sigma spectra in various processes, such as the K-d -> pi Sigma n
reaction and the Lambda_c -> pi pi Sigma decay. The structure of the
Lambda(1405) is found to be dominated by an antikaon-nucleon molecular
configuration, based on its wavefunction derived from a realistic Kbar N
potential and the compositeness criteria from a model-independent weak-binding
relation.


title:
An advective-spectral-mixed method for time-dependent many-body Wigner
  simulations

abstract:
  As a phase space language for quantum mechanics, the Wigner function approach
bears a close analogy to classical mechanics and has been drawing growing
attention, especially in simulating quantum many-body systems. However,
deterministic numerical solutions have been almost exclusively confined to
one-dimensional one-body systems and few results are reported even for
one-dimensional two-body problems. This paper serves as the first attempt to
solve the time-dependent many-body Wigner equation through a grid-based
advective-spectral-mixed method. The main feature of the method is to resolve
the linear advection in $(\bm{x},t)$-space by an explicit three-step
characteristic scheme coupled with the piecewise cubic spline interpolation,
while the Chebyshev spectral element method in $\bm k$-space is adopted for
accurate calculation of the nonlocal pseudo-differential term. Not only the
time step of the resulting method is not restricted by the usual CFL condition
and thus a large time step is allowed, but also the mass conservation can be
maintained. In particular, for the system consisting of identical particles,
the advective-spectral-mixed method can also rigorously preserve physical
symmetry relations. The performance is validated through several typical
numerical experiments, like the Gaussian barrier scattering, electron-electron
interaction and a Helium-like system, where the third-order accuracy against
both grid spacing and time stepping is observed.


title: Fuglede's spectral set conjecture for convex polytopes

abstract:
  Let $\Omega$ be a convex polytope in $\mathbb{R}^d$. We say that $\Omega$ is
spectral if the space $L^2(\Omega)$ admits an orthogonal basis consisting of
exponential functions. There is a conjecture, which goes back to Fuglede
(1974), that $\Omega$ is spectral if and only if it can tile the space by
translations. It is known that if $\Omega$ tiles then it is spectral, but the
converse was proved only in dimension $d=2$, by Iosevich, Katz and Tao.
  By a result due to Kolountzakis, if a convex polytope $\Omega\subset
\mathbb{R}^d$ is spectral, then it must be centrally symmetric. We prove that
also all the facets of $\Omega$ are centrally symmetric. These conditions are
necessary for $\Omega$ to tile by translations.
  We also develop an approach which allows us to prove that in dimension $d=3$,
any spectral convex polytope $\Omega$ indeed tiles by translations. Thus we
obtain that Fuglede's conjecture is true for convex polytopes in
$\mathbb{R}^3$.


title:
Pandora: Description of a Painting Database for Art Movement Recognition
  with Baselines and Perspectives

abstract:
  To facilitate computer analysis of visual art, in the form of paintings, we
introduce Pandora (Paintings Dataset for Recognizing the Art movement)
database, a collection of digitized paintings labelled with respect to the
artistic movement. Noting that the set of databases available as benchmarks for
evaluation is highly reduced and most existing ones are limited in variability
and number of images, we propose a novel large scale dataset of digital
paintings. The database consists of more than 7700 images from 12 art
movements. Each genre is illustrated by a number of images varying from 250 to
nearly 1000. We investigate how local and global features and classification
systems are able to recognize the art movement. Our experimental results
suggest that accurate recognition is achievable by a combination of various
categories.To facilitate computer analysis of visual art, in the form of
paintings, we introduce Pandora (Paintings Dataset for Recognizing the Art
movement) database, a collection of digitized paintings labelled with respect
to the artistic movement. Noting that the set of databases available as
benchmarks for evaluation is highly reduced and most existing ones are limited
in variability and number of images, we propose a novel large scale dataset of
digital paintings. The database consists of more than 7700 images from 12 art
movements. Each genre is illustrated by a number of images varying from 250 to
nearly 1000. We investigate how local and global features and classification
systems are able to recognize the art movement. Our experimental results
suggest that accurate recognition is achievable by a combination of various
categories.


title:
Theory of a 3+1D fractional chiral metal: interacting variant of the
  Weyl semimetal

abstract:
  Formulating consistent theories describing strongly correlated metallic
topological phases is an outstanding problem in condensed matter physics. In
this work we derive a theory defining a fractionalized analogue of the Weyl
semimetal state: the fractional chiral metal. Our approach is to construct a
4+1D quantum Hall insulator by stacking 3+1D Weyl semimetals in a magnetic
field. In a strong enough field the low-energy physics is determined by the
lowest Landau level of each Weyl semimetal, which is highly degenerate and
chiral, motivating us to use a coupled-wire approach. The one-dimensional
dispersion of the lowest Landau level allows us to model the system as a set of
degenerate 1+1D quantum wires that can be bosonized in the presence of
electron-electron interactions and coupled such that a gapped phase is
obtained, whose response to an electromagnetic field is given in terms of a
Chern-Simons field theory. At the boundary of this phase we obtain the field
theory of a 3+1D gapless fractional chiral state, which we show is consistent
with a previous theory for the surface of a 4+1D Chern-Simons theory. The
boundary's response to an external electromagnetic field is determined by a
chiral anomaly with a fractionalized coefficient. We suggest that such
anomalous response can be taken as a working definition of a fractionalized
strongly correlated analogue of the Weyl semimetal state.


title: Selective Uplink Training for Massive MIMO Systems

abstract:
  As a promising technique to meet the drastically growing demand for both high
throughput and uniform coverage in the fifth generation (5G) wireless networks,
massive multiple-input multiple-output (MIMO) systems have attracted
significant attention in recent years. However, in massive MIMO systems, as the
density of mobile users (MUs) increases, conventional uplink training methods
will incur prohibitively high training overhead, which is proportional to the
number of MUs. In this paper, we propose a selective uplink training method for
massive MIMO systems, where in each channel block only part of the MUs will
send uplink pilots for channel training, and the channel states of the
remaining MUs are predicted from the estimates in previous blocks, taking
advantage of the channels' temporal correlation. We propose an efficient
algorithm to dynamically select the MUs to be trained within each block and
determine the optimal uplink training length. Simulation results show that the
proposed training method provides significant throughput gains compared to the
existing methods, while much lower estimation complexity is achieved. It is
observed that the throughput gain becomes higher as the MU density increases.


title: Discretizing Malliavin calculus

abstract:
  Suppose $B$ is a Brownian motion and $B^n$ is an approximating sequence of
rescaled random walks on the same probability space converging to $B$ pointwise
in probability. We provide necessary and sufficient conditions for weak and
strong $L^2$-convergence of a discretized Malliavin derivative, a discrete
Skorokhod integral, and discrete analogues of the Clark-Ocone derivative to
their continuous counterparts. Moreover, given a sequence $(X^n)$ of random
variables which admit a chaos decomposition in terms of discrete multiple
Wiener integrals with respect to $B^n$, we derive necessary and sufficient
conditions for strong $L^2$-convergence to a $\sigma(B)$-measurable random
variable $X$ via convergence of the discrete chaos coefficients of $X^n$ to the
continuous chaos coefficients of $X$. In the special case of binary noise, our
results support the known formal analogies between Malliavin calculus on the
Wiener space and Malliavin calculus on the Bernoulli space by rigorous
$L^2$-convergence results.


title: Companion points and locally analytic socle for $\mathrm{GL}_2(L)$

abstract:
  Let $p>2$ be a prime number, and $L$ be a finite extension of $\mathbb{Q}_p$,
we prove Breuil's locally analytic socle conjecture for $\mathrm{GL}_2(L)$,
showing the existence of all the companion points on the definite (patched)
eigenvariety. This work relies on infinitesimal "R=T" results for the patched
eigenvariety and the comparison of (partially) de Rham families and (partially)
Hodge-Tate families. This method allows in particular to find companion points
of non-classical points.


title: An Adiabatic Quantum Algorithm for Determining Gracefulness of A Graph

abstract:
  Graph labelling is one of the noticed contexts in combinatorics and graph
theory. Graceful labelling for a graph $G$ with $e$ edges, is to label the
vertices of $G$ with $0, 1, \cdots, e$ such that, if we specify to each edge
the difference value between its two ends, then any of $1, 2, \cdots, e$
appears exactly once as an edge label. For a given graph, there is still few
efficient classical algorithms that determines either it is graceful or not,
even for trees - as a well-known class of graphs. In this paper, we introduce
an adiabatic quantum algorithm, which for a graceful graph $G$ finds a graceful
labelling. Also, this algorithm can determine if $G$ is not graceful. Numerical
simulations of the algorithm reveal that its time complexity has a polynomial
behaviour with the problem size up to the range of 15 qubits.


title:
Bayesian inference for age-structured population model of infectious
  disease with application to varicella in Poland

abstract:
  Dynamics of the infectious disease transmission is often best understood
taking into account the structure of population with respect to specific
features, in example age or immunity level. Practical utility of such models
depends on the appropriate calibration with the observed data. Here, we discuss
the Bayesian approach to data assimilation in case of two-state age-structured
model. This kind of models are frequently used to describe the disease dynamics
(i.e. force of infection) basing on prevalence data collected at several time
points. We demonstrate that, in the case when the explicit solution to the
model equation is known, accounting for the data collection process in the
Bayesian framework allows to obtain an unbiased posterior distribution for the
parameters determining the force of infection. We further show analytically and
through numerical tests that the posterior distribution of these parameters is
stable with respect to cohort approximation (Escalator Boxcar Train) to the
solution. Finally, we apply the technique to calibrate the model based on
observed sero-prevalence of varicella in Poland.


title: The local density of optical states of a metasurface

abstract:
  While metamaterials are often desirable for near-field functions, such as
perfect lensing, or cloaking, they are often quantified by their response to
plane waves from the far field. Here, we present a theoretical analysis of the
local density of states near lattices of discrete magnetic scatterers, i.e.,
the response to near field excitation by a point source. Based on a
point-dipole theory using Ewald summation and an array scanning method, we can
swiftly and semi-analytically evaluate the local density of states (LDOS) for
magnetoelectric point sources in front of an infinite two-dimensional (2D)
lattice composed of arbitrary magnetoelectric dipole scatterers. The method
takes into account radiation damping as well as all retarded electrodynamic
interactions in a self-consistent manner. We show that a lattice of magnetic
scatterers evidences characteristic Drexhage oscillations. However, the
oscillations are phase shifted relative to the electrically scattering lattice
consistent with the difference expected for reflection off homogeneous magnetic
respectively electric mirrors. Furthermore, we identify in which source-surface
separation regimes the metasurface may be treated as a homogeneous interface,
and in which homogenization fails. A strong frequency and in-plane position
dependence of the LDOS close to the lattice reveals coupling to guided modes
supported by the lattice.


title: Choreographies in Practice

abstract:
  Choreographic Programming is a development methodology for concurrent
software that guarantees correctness by construction. The key to this paradigm
is to disallow mismatched I/O operations in programs, called choreographies,
and then mechanically synthesise distributed implementations in terms of
standard process models via a mechanism known as EndPoint Projection (EPP).
  Despite the promise of choreographic programming, there is still a lack of
practical evaluations that illustrate the applicability of choreographies to
concrete computational problems with standard concurrent solutions. In this
work, we explore the potential of choreographies by using Procedural
Choreographies (PC), a model that we recently proposed, to write distributed
algorithms for sorting (Quicksort), solving linear equations (Gaussian
elimination), and computing Fast Fourier Transform. We discuss the lessons
learned from this experiment, giving possible directions for the usage and
future improvements of choreography languages.


title: Bounding Betti numbers of monomial ideals in the exterior algebra

abstract:
  Let $K$ be a field, $V$ a $K$-vector space with basis $e_1,\ldots,e_n$, and
$E$ the exterior algebra of $V$. To a given monomial ideal $I\subsetneq E$ we
associate a special monomial ideal $J$ with generators in the same degrees as
those of $I$ and such that the number of the minimal monomial generators in
each degree of $I$ and $J$ coincide. We call $J$ the colexsegment ideal
associated to $I$. We prove that the class of strongly stable ideals in $E$
generated in one degree satisfies the colex lower bound, that is, the total
Betti numbers of the colexsegment ideal associated to a strongly stable ideal
$I\subsetneq E$ generated in one degree are smaller than or equal to those of
$I$.


title:
Robust quantum state recovery from amplitude damping within a mixed
  states framework

abstract:
  Due to the interaction with the environment, a quantum state is subjected to
decoherence which becomes one of the biggest problems for practical quantum
computation. Amplitude damping is one of the most important decoherence
processes. Here, we show that general two-qubit mixed states undergoing an
amplitude damping can be almost completely restored using a reversal procedure.
This reversal procedure through CNOT and Hadamard gates, could also protect the
entanglement of two-qubit mixed states, when it undergoes general amplitude
damping. Moreover, in the presence of uncertainty in the underlying system, we
propose a robust recovering method with optimal characteristics of the problem.


title:
Birational maps preserving the contact structure on
  $\mathbb{P}^3_\mathbb{C}$

abstract:
  We study the group of polynomial automorphisms of $\mathbb{C}^3$ (resp.
birational self-maps of $\mathbb{P}^3_\mathbb{C}$) that preserve the contact
structure.


title: A non-crossing word cooperad for free homotopy probability theory

abstract:
  We construct a cooperad which extends the framework of homotopy probability
theory to free probability theory. The cooperad constructed, which seems
related to the sequence and cactus operads, may be of independent interest.


title: A Global Correction to PPMXL Proper Motions

abstract:
  In this paper we notice that extragalactic sources seem to have non-zero
proper motions in the PPMXL proper motion catalog. We collect a large, all-sky
sample of extragalactic objects and fit their reported PPMXL proper motions to
an ensemble of spherical harmonics in magnitude shells. A magnitude dependent
proper motion correction is thus constructed.
  This correction is applied to a set of fundamental radio sources, quasars,
and is compared to similar corrections to assess its utility. We publish, along
with this paper, code which may be used to correct proper motions in the PPMXL
catalog over the full sky which have 2 Micron All Sky Survey photometry.


title:
High-energy sources at low radio frequency: the Murchison Widefield
  Array view of Fermi blazars

abstract:
  Low-frequency radio arrays are opening a new window for the study of the sky,
both to study new phenomena and to better characterize known source classes.
Being flat-spectrum sources, blazars are so far poorly studied at low radio
frequencies.
  We characterize the spectral properties of the blazar population at low radio
frequency compare the radio and high-energy properties of the gamma-ray blazar
population, and search for radio counterparts of unidentified gamma-ray
sources.
  We cross-correlated the 6,100 deg^2 Murchison Widefield Array Commissioning
Survey catalogue with the Roma blazar catalogue, the third catalogue of active
galactic nuclei detected by Fermi-LAT, and the unidentified members of the
entire third catalogue of gamma-ray sources detected by \fermilat. When
available, we also added high-frequency radio data from the Australia Telescope
20 GHz catalogue.
  We find low-frequency counterparts for 186 out of 517 (36%) blazars, 79 out
of 174 (45%) gamma-ray blazars, and 8 out of 73 (11%) gamma-ray blazar
candidates. The mean low-frequency (120--180 MHz) blazar spectral index is
$\langle \alpha_\mathrm{low} \rangle=0.57\pm0.02$: blazar spectra are flatter
than the rest of the population of low-frequency sources, but are steeper than
at $\sim$GHz frequencies. Low-frequency radio flux density and gamma-ray energy
flux display a mildly significant and broadly scattered correlation. Ten
unidentified gamma-ray sources have a (probably fortuitous) positional match
with low radio frequency sources.
  Low-frequency radio astronomy provides important information about sources
with a flat radio spectrum and high energy. However, the relatively low
sensitivity of the present surveys still misses a significant fraction of these
objects. Upcoming deeper surveys, such as the GaLactic and Extragalactic
All-Sky MWA (GLEAM) survey, will provide further insight into this population.


title:
Free energy approach to micellization and aggregation: Equilibrium,
  metastability, and kinetics

abstract:
  We review a recently developed micellization theory, which is based on a
free-energy approach and offers several advantages over the conventional one,
based on mass action and rate equations. As all the results are derived from a
single free-energy expression, one can adapt the theory to different scenarios
by merely modifying the initial expression. We present results concerning
various features of micellization out of equilibrium, such as the existence of
metastable aggregates (premicelles), micellar nucleation and growth, transient
aggregates, and final relaxation toward equilibrium. Several predictions that
await experimental investigation are discussed.


title: Modes of decay in neutron-rich nuclei

abstract:
  We calculate the ground, first intrinsic excited states and density
distribution for neutron-rich thorium and uranium isotopes, within the
framework of relativistic mean field(RMF) approach using axially deformed
basis. The total nucleon densities are calculated, from which the
cluster-structures inside the parent nuclei are determined. The possible modes
of decay, like {\alpha}-decay and \b{eta} -decay are analyzed. We find the
neutron-rich isotopes are stable against {\alpha}-decay, however they are very
much unstable against \b{eta} -decay. The life time of these nuclei predicted
to be tens of second against \b{eta} -decay.


title: Weak Value, Quasiprobability and Bohmian Mechanics

abstract:
  We clarify the significance of quasiprobability (QP) in quantum mechanics
that is relevant in describing physical quantities associated with a transition
process. Our basic quantity is Aharonov's weak value, from which the QP can be
defined up to a certain ambiguity parameterized by a complex number. Unlike the
conventional probability, the QP allows us to treat two noncommuting
observables consistently, and this is utilized to embed the QP in Bohmian
mechanics such that its equivalence to quantum mechanics becomes more
transparent. We also show that, with the help of the QP, Bohmian mechanics can
be recognized as an ontological model with a certain type of contextuality.


title: A long exact sequence for homology of FI-modules

abstract:
  We construct a long exact sequence involving the homology of an FI-module.
Using the long exact sequence, we give two methods to bound the
Castelnuovo-Mumford regularity of an FI-module which is generated and related
in finite degree. We also prove that for an FI-module which is generated and
related in finite degree, if it has a nonzero higher homology, then its
homological degrees are strictly increasing (starting from the first
homological degree).


title:
A medium-resolution monochromator for 73 keV x-rays - Nuclear resonant
  scattering of synchrotron radiation from 193-Ir

abstract:
  We report on the development and characterization of a medium resolution
monochromator for synchrotron-based hyperfine spectroscopy at the 73 keV
nuclear resonance of 193-Ir. The device provides high throughput of 6*10^8 ph/s
in an energy bandwidth of 300(20) meV. We excited the nuclear resonance in
193-Ir at 73.04 keV and observed nuclear fluorescence of 193-Ir in Iridium
metal. The monochromator allows for Nuclear Forward Scattering spectroscopy on
Ir and its compounds.


title: The maximum of the CUE field

abstract:
  Let $U_N$ denote a Haar Unitary matrix of dimension N, and consider the field
\[ {\bf U}(z) = \log |\det(1-zU_N)| \] for z in the unit disk. Then, \[
\frac{\max_{|z|=1} {\bf U}(z) -\log N + \frac{3}{4} \log\log N} {\log\log N}
\to 0 \] in probability. This provides a verification up to second order of a
conjecture of Fyodorov, Hiary and Keating, improving on the recent first order
verification of Arguin, Belius and Bourgade.


title:
Octahedral, dicyclic and special linear solutions of some unsolved
  Hamilton-Waterloo problems

abstract:
  We give a sharply-vertex-transitive solution of each of the nine
Hamilton-Waterloo problems left open by Danziger, Quattrocchi and Stevens.


title:
Design of PAR-Constrained Sequences for MIMO Channel Estimation via
  Majorization-Minimization

abstract:
  PAR-constrained sequences are widely used in communication systems and radars
due to various practical needs; specifically, sequences are required to be
unimodular or of low peak-to-average power ratio (PAR). For unimodular sequence
design, plenty of efforts have been devoted to obtaining good correlation
properties. Regarding channel estimation, however, sequences of such properties
do not necessarily help produce optimal estimates. Tailored unimodular
sequences for the specific criterion concerned are desirable especially when
the prior knowledge of the channel is taken into account as well. In this
paper, we formulate the problem of optimal unimodular sequence design for
minimum mean square error estimation of the channel impulse response and
conditional mutual information maximization, respectively. Efficient algorithms
based on the majorization-minimization framework are proposed for both problems
with guaranteed convergence. As the unimodular constraint is a special case of
the low PAR constraint, optimal sequences of low PAR are also considered.
Numerical examples are provided to show the performance of the proposed
training sequences, with the efficiency of the derived algorithms demonstrated.


title:
Some Theoretical Aspects of Quantum Mechanical Equations in Rindler
  Space

abstract:
  In this article we have investigated some of the theoretical aspects of the
solutions of quantum mechanical equations in Rindler space. We have developed
the formalism for exact analytical solutions for Schr$\ddot{\rm{o}}$dinger
equation and Klein-Gordon equation. Along with the approximate form of
solutions for these two quantum mechanical equations. We have discussed the
physical significance of our findings. The Hamiltonian operator in Rindler
space is found to be non-Hermitian in nature. But the energy eigen values or
the energy eigen spectra are observed to be real. We have noticed that the sole
reason behind such real behavior is the PT symmetric form of the Hamiltonian
operator.


title: Skolem Circles

abstract:
  Skolem sequences and Skolem labeled graphs have been described and examined
for several decades. This note explores weak Skolem labelling of cycle graphs,
which we call Skolem circles. The relationship between Skolem sequences and
Skolem cirlces is explored, and Skolem circles of small sizes are enumerated,
with some loose general bounds established.


title:
The $\bf{\Lambda p}$ interaction studied via femtoscopy in p + Nb
  reactions at $\mathbf{\sqrt{s_{NN}}=3.18} ~\mathrm{\bf{GeV}}$

abstract:
  We report on the first measurement of $p\Lambda$ and $pp$ correlations via
the femtoscopy method in p+Nb reactions at $\mathrm{\sqrt{s_{NN}}=3.18}
~\mathrm{GeV}$, studied with the High Acceptance Di-Electron Spectrometer
(HADES). By comparing the experimental correlation function to model
calculations, a source size for $pp$ pairs of $r_{0,pp}=2.02 \pm
0.01(\mathrm{stat})^{+0.11}_{-0.12} (\mathrm{sys}) ~\mathrm{fm}$ and a slightly
smaller value for $p\Lambda$ of $r_{0,\Lambda p}=1.62 \pm
0.02(\mathrm{stat})^{+0.19}_{-0.08}(\mathrm{sys}) ~\mathrm{fm}$ is extracted.
Using the geometrical extent of the particle emitting region, determined
experimentally with $pp$ correlations as reference together with a source
function from a transport model, it is possible to study different sets of
scattering parameters. The $p\Lambda$ correlation is proven sensitive to
predicted scattering length values from chiral effective field theory. We
demonstrate that the femtoscopy technique can be used as valid alternative to
the analysis of scattering data to study the hyperon-nucleon interaction.


title: Brain State Control by Closed-Loop Environmental Feedback

abstract:
  Brain state regulates sensory processing and motor control for adaptive
behavior. Internal mechanisms of brain state control are well studied, but the
role of external modulation from the environment is not well understood. Here,
we examined the role of closed-loop environmental (CLE) feedback, in comparison
to open-loop sensory input, on brain state and behavior in diverse vertebrate
systems. In fictively swimming zebrafish, CLE feedback for optomotor stability
controlled brain state by reducing coherent neuronal activity. The role of CLE
feedback in brain state was also shown in a model of rodent active whisking,
where brief interruptions in this feedback enhanced signal-to-noise ratio for
detecting touch. Finally, in monkey visual fixation, artificial CLE feedback
suppressed stimulus-specific neuronal activity and improved behavioral
performance. Our findings show that the environment mediates continuous
closed-loop feedback that controls neuronal gain, regulating brain state, and
that brain function is an emergent property of brain-environment interactions.


title:
Conjugate variables in quantum field theory and a refinement of Paulis
  theorem

abstract:
  For the case of spin zero we construct conjugate pairs of operators on Fock
space. On states multiplied by polarization vectors coordinate operators Q
conjugate to the momentum operator P exist. The massive case is derived from a
geometrical quantity, the massless case is realized by taking the limit mass
going to zero on the one hand, on the other from conformal transformations.
Crucial is the norm problem of the states on which the Q's act: they determine
eventually how many independent conjugate pairs exist. It is intriguing that
light wedge variables and hence the wedge-local case seems to be preferred.


title: Spectra of definite type in waveguide models

abstract:
  We develop an abstract method to identify spectral points of definite type in
the spectrum of the operator $T_1\otimes I_2 + I_1\otimes T_2$. The method is
applicable in particular for non-self-adjoint waveguide type operators with
symmetries. Using the remarkable properties of the spectral points of definite
type, we obtain new results on realness of weakly coupled bound states and of
low lying essential spectrum in the $\mathcal{P}\mathcal{T}$-symmetric
waveguide. Moreover, we show that the pseudospectrum has a normal tame behavior
near the low lying essential spectrum and exclude the accumulation of non-real
eigenvalues to this part of the essential spectrum. The advantage of our
approach is particularly visible when the resolvent of the unperturbed operator
cannot be explicitly expressed and most of the mentioned spectral conclusions
are extremely hard to prove using direct methods.


title: A CsI low temperature detector for dark matter search

abstract:
  Cryogenic detectors have a long history of success in the field of rare event
searches. In particular scintillating calorimeters are very suitable detectors
for this task since they provide particle discrimination: the simultaneous
detection of the thermal and the light signal produced by a particle
interaction in scintillating crystals allows to identify the nature of
particle, as the light yield depends thereon. We investigate the performance of
two large CsI (undoped) crystals ($\sim$122 g each) operated as scintillating
calorimeters at milli-Kelvin temperatures in terms of calorimetric properties
and background rejection capabilities. Furthermore, we discuss the feasibility
of this detection approach towards a background-free future dark matter
experiment based on alkali halides crystals, with active particle
discrimination via the two-channel detection.


title:
Charge transfer, band-like transport, and magnetic ions at
  F16CoPc/rubrene interfaces

abstract:
  Organic semiconductors offer an unprecedented flexibility to control the
electronic state of interfacial electronic systems. Here we present a first
step in realizing organic charge transfer interfaces that combine both a large
electrical conductivity and the presence of magnetic ions. We have performed a
detailed investigation of F16CoPc/rubrene interface by means of temperature
dependent charge transport measurements, Hall effect, scanning Kelvin probe
microscopy and photoelectron spectroscopy. Our finding is that the charge
transfer leads to significantly enhanced electrical conductivity and the
band-like transport. We have determined the density, mobility and nature of
charge carriers in the system (holes in rubrene). We have also found that the
amount of charge transfer in F16CoPc/rubrene is high enough to cause the
band-like transport in rubrene crystals at the interface. Finally, our XPS and
UPS measurements have shown that the charge transfer in F16CoPc/rubrene
involves electronic orbitals centered on the magnetic Co ions of the
phthalocyanine molecules causing a change in their spin. Thus, F16CoPc/rubrene
is the first organic interface where the charge transfer responsible for the
interfacial conductivity fully involves the metal Co core of the phthalocyanine
molecules, providing a link between charge transport and magnetic properties.


title: Collaborative Learning of Stochastic Bandits over a Social Network

abstract:
  We consider a collaborative online learning paradigm, wherein a group of
agents connected through a social network are engaged in playing a stochastic
multi-armed bandit game. Each time an agent takes an action, the corresponding
reward is instantaneously observed by the agent, as well as its neighbours in
the social network. We perform a regret analysis of various policies in this
collaborative learning setting. A key finding of this paper is that natural
extensions of widely-studied single agent learning policies to the network
setting need not perform well in terms of regret. In particular, we identify a
class of non-altruistic and individually consistent policies, and argue by
deriving regret lower bounds that they are liable to suffer a large regret in
the networked setting. We also show that the learning performance can be
substantially improved if the agents exploit the structure of the network, and
develop a simple learning algorithm based on dominating sets of the network.
Specifically, we first consider a star network, which is a common motif in
hierarchical social networks, and show analytically that the hub agent can be
used as an information sink to expedite learning and improve the overall
regret. We also derive networkwide regret bounds for the algorithm applied to
general networks. We conduct numerical experiments on a variety of networks to
corroborate our analytical results.


title:
The valuation of American options in a multidimensional exponential Levy
  model

abstract:
  We consider the problem of valuation of American options written on
dividend-paying assets whose price dynamics follows a multidimensional
exponential Levy model. We carefully examine the relation between the option
prices, related partial integro-differential variational inequalities and
reflected backward stochastic differential equations. In particular, we prove
regularity results for the value function and obtain the early exercise premium
formula for broad class of payoff functions.


title: Effects of isovector scalar meson on hyperon star

abstract:
  We study the effects of isovector-scalar ($\delta$)-meson on neutron star.
Influence of $\delta$-meson on both static and rotating neutron star is
discussed. Inclusion of $\delta$-meson in a neutron star system consisting of
proton, neutron and electron, make the equation of state stiffer in higher
density and consequently increases the maximum mass of the star. But induction
of $\delta$-meson in the hyperon star decreases the maximum mass of the hyperon
star. This is due to the early evolution of hyperons in presence of
$\delta-$meson.


title:
Folding of Protein L with implications for collapse in the denatured
  state ensemble

abstract:
  A fundamental question in protein folding is whether the coil to globule
collapse transition occurs during the initial stages of folding (burst-phase)
or simultaneously with the protein folding transition. Single molecule
fluorescence resonance energy transfer (FRET) and small angle X-ray scattering
(SAXS) experiments disagree on whether Protein L collapse transition occurs
during the burst-phase of folding. We study Protein L folding using a
coarse-grained model and molecular dynamics simulations. The collapse
transition in Protein L is found to be concomitant with the folding transition.
In the burst-phase of folding, we find that FRET experiments overestimate
radius of gyration, $R_g$, of the protein due to the application of Gaussian
polymer chain end-to-end distribution to extract $R_g$ from the FRET
efficiency. FRET experiments estimate $\approx$ 6\AA \ decrease in $R_g$ when
the actual decrease is $\approx$ 3\AA \ on Guanidinium Chloride denaturant
dilution from 7.5M to 1M, and thereby suggesting pronounced compaction in the
protein dimensions in the burst-phase. The $\approx$ 3\AA \ decrease is close
to the statistical uncertainties of the $R_g$ data measured from SAXS
experiments, which suggest no compaction, leading to a disagreement with the
FRET experiments. The transition state ensemble (TSE) structures in Protein L
folding are globular and extensive in agreement with the $\Psi$-analysis
experiments. The results support the hypothesis that the TSE of single domain
proteins depend on protein topology, and are not stabilised by local
interactions alone.


title: Exact symmetries in the velocity fluctuations of a hot Brownian swimmer

abstract:
  Symmetries constrain dynamics. We test this fundamental physical principle,
experimentally and by molecular dynamics simulations, for a hot Janus swimmer
operating far from thermal equilibrium. Our results establish scalar and
vectorial steady-state fluctuation theorems and a thermodynamic uncertainty
relation that link the fluctuating particle current to its entropy production
at an effective temperature. A Markovian minimal model elucidates the
underlying non-equilbrium physics.


title:
On the analogy between real reductive groups and Cartan motion groups.
  III: A proof of the Connes-Kasparov isomorphism

abstract:
  Alain Connes and Nigel Higson pointed out in the 1990s that the
Connes-Kasparov "conjecture"' for the K-theory of reduced groupe
$C^\ast$-algebras seemed, in the case of reductive Lie groups, to be a
cohomological echo of a conjecture of George Mackey concerning the rigidity of
representation theory along the deformation from a reductive Lie group to its
Cartan motion group. For complex semisimple groups, Nigel Higson established in
2008 that Mackey's analogy is a real phenomenon and does lead to a simple proof
of the Connes-Kasparov isomorphism. We here turn to more general reductive
groups and use our recent work on Mackey's proposal, together with Higson's
work, to obtain a new proof of the Connes-Kasparov isomorphism.


title:
Interlayer interaction and related properties of bilayer hexagonal boron
  nitride: ab initio study

abstract:
  Principal characteristics of interlayer interaction and relative motion of
hexagonal boron nitride (h-BN) layers are investigated by the first-principles
method taking into account van der Waals interactions. Dependences of the
interlayer interaction energy on relative translational displacement of h-BN
layers (potential energy surfaces) are calculated for two relative orientations
of the layers, namely, for the layers aligned in the same direction and in the
opposite directions upon relative rotation of the layers by 180 degrees. It is
shown that the potential energy surfaces of bilayer h-BN can be approximated by
the first Fourier components determined by symmetry. As a result, a wide set of
physical qualintities describing relative motion of h-BN layers aligned in the
same direction including barriers to their relative sliding and rotation, shear
mode frequency and shear modulus are determined by a single parameter
corresponding to the roughness of the potential energy surface, similar to
bilayer graphene. The properties of h-BN layers aligned in the opposite
directions are described by two such parameters. The possibility of partial and
full dislocations in stacking of the layers is predicted for h-BN layers
aligned in the same and opposite directions, respectively. The extended
two-chain Frenkel-Kontorova model is used to estimate the width and formation
energy of these dislocations on the basis of the calculated potential energy
surfaces.


title:
The correlation between fragility, density and atomic interaction in
  glass-forming liquids

abstract:
  The fragility, that controls the temperature-dependent viscous properties of
liquids as the glass transition is approached, in various glass-forming liquids
with different atomic interactions and densities is investigated by molecular
dynamic simulations. We show the landscape of fragility in purely repulsive
systems can be separated into three regions with qualitatively disparate
dynamic behaviors, suggesting that the density plays an unexpected role for
understanding the repulsive steepness dependence of fragility. Furthermore, the
vastly dissimilar influences of attractive interaction on fragility could be
estimated from the structural properties of related zero-temperature glasses


title:
Improved Fr\'echet$-$Hoeffding bounds on $d$-copulas and applications in
  model-free finance

abstract:
  We derive upper and lower bounds on the expectation of $f(\mathbf{S})$ under
dependence uncertainty, i.e. when the marginal distributions of the random
vector $\mathbf{S}=(S_1,\dots,S_d)$ are known but their dependence structure is
partially unknown. We solve the problem by providing improved \FH bounds on the
copula of $\mathbf{S}$ that account for additional information. In particular,
we derive bounds when the values of the copula are given on a compact subset of
$[0,1]^d$, the value of a functional of the copula is prescribed or different
types of information are available on the lower dimensional marginals of the
copula. We then show that, in contrast to the two-dimensional case, the bounds
are quasi-copulas but fail to be copulas if $d>2$. Thus, in order to translate
the improved \FH bounds into bounds on the expectation of $f(\mathbf{S})$, we
develop an alternative representation of multivariate integrals with respect to
copulas that admits also quasi-copulas as integrators. By means of this
representation, we provide an integral characterization of orthant orders on
the set of quasi-copulas which relates the improved \FH bounds to bounds on the
expectation of $f(\mathbf{S})$. Finally, we apply these results to compute
model-free bounds on the prices of multi-asset options that take partial
information on the dependence structure into account, such as correlations or
market prices of other traded derivatives. The numerical results show that the
additional information leads to a significant improvement of the option price
bounds compared to the situation where only the marginal distributions are
known.


title:
New properties of a certain method of summation of generalized
  hypergeometric series

abstract:
  In a recent paper (Appl. Math. Comput. 215, 1622--1645, 2009), the authors
proposed a method of summation of some slowly convergent series. The purpose of
this note is to give more theoretical analysis for this transformation,
including the convergence acceleration theorem in the case of summation of
generalized hypergeometric series. Some new theoretical results and
illustrative numerical examples are given.


title: Dynamical crossing of an infinitely degenerate critical point

abstract:
  We study the evolution of a driven harmonic oscillator with a time-dependent
frequency $\omega_t \propto |t|$. At time $t=0$ the Hamiltonian undergoes a
point of infinite spectral degeneracy. If the system is initialized in the
instantaneous vacuum in the distant past then the asymptotic future state is a
squeezed state whose parameters are explicitly determined. We show that the
squeezing is independent on the sweeping rate. This manifests the failure of
the adiabatic approximation at points where infinitely many eigenvalues
collide. We extend our analysis to the situation where the gap at $t=0$ remains
finite. We also discuss the natural geometry of the manifold of squeezed
states. We show that it is realized by the Poincar\'e disk model viewed as a
K\"ahler manifold.


title: Dispersion laws of the two-dimensional cavity magnetoexciton-polaritons

abstract:
  The energy spectrum of the 2D cavity magnetoexciton-polaritons has been
investigated previously, using exact solutions for the Landau quantization of
conduction electrons and heavy holes provided by the Rashba method [1]. Two
lowest Landau quantization levels for electrons and three lowest Landau levels
for heavy-holes, lead to the construction of the six lowest magnetoexciton
sates. They consist of two dipole-active, two quadrupole-active, and the two
forbidden quantum transitions from the ground state of the crystal to the
magnetoexciton states. The interaction of the four optical-active
magnetoexciton states with the cavity mode photons with a given circular
polarization and with well-defined incidence direction leads to the creation of
five magnetoexciton-polariton branches. The fifth order dispersion equation is
examined by using numerical calculations and the second order dispersion
equation is solved analytically, taking into account only one dipole-active
magnetoexciton state. The effective polariton mass on the lower polariton
branch, the Rabi frequency and the corresponding Hopfield coefficients are
determined in dependence on the magnetic field strength, the Rashba spin-orbit
coupling parameters and the electron and hole g-factors.


title: Converse bounds for private communication over quantum channels

abstract:
  This paper establishes several converse bounds on the private transmission
capabilities of a quantum channel. The main conceptual development builds
firmly on the notion of a private state, which is a powerful, uniquely quantum
method for simplifying the tripartite picture of privacy involving local
operations and public classical communication to a bipartite picture of quantum
privacy involving local operations and classical communication. This approach
has previously led to some of the strongest upper bounds on secret key rates,
including the squashed entanglement and the relative entropy of entanglement.
Here we use this approach along with a "privacy test" to establish a general
meta-converse bound for private communication, which has a number of
applications. The meta-converse allows for proving that any quantum channel's
relative entropy of entanglement is a strong converse rate for private
communication. For covariant channels, the meta-converse also leads to
second-order expansions of relative entropy of entanglement bounds for private
communication rates. For such channels, the bounds also apply to the private
communication setting in which the sender and receiver are assisted by
unlimited public classical communication, and as such, they are relevant for
establishing various converse bounds for quantum key distribution protocols
conducted over these channels. We find precise characterizations for several
channels of interest and apply the methods to establish several converse bounds
on the private transmission capabilities of all phase-insensitive bosonic
channels.


title:
Dynamics of large-scale solar-wind streams obtained by the double
  superposed epoch analysis. 2. CIR.vs.Sheath and MC.vs.Ejecta comparisons

abstract:
  This work is a continuation of our previous paper [Yermolaevetal2015] which
describes the average temporal profiles of interplanetary plasma and field
parameters in large-scale solar-wind (SW) streams: CIR, ICME (both MC and
Ejecta) and Sheath as well as the interplanetary shock (IS). Like in the
previous work we use data of OMNI database, our catalog of large-scale
solar-wind phenomena during 1976--2000 [Yermolaevetal2009] and the double
superposed epoch analysis (DSEA) method [Yermolaevetal2010]: re-scaling the
duration of interval for all types in such a manner that, respectively,
beginning and end for all intervals of selected type coincide. We present new
detailed results of comparison of two pair phenomena: (1) both types of
compression regions (CIR.vs.Sheath) and (2) both types of ICMEs (MC.vs.Ejecta).
Obtained data allows us to suggest that the formation of all types of
compression regions has the same physical mechanism irrespective of piston
(High-Speed Stream (HSS) or ICME) type and differences are connected with
geometry (angle between speed gradient in front of piston and satellite
trajectory) and full jumps of speed in edges of compression regions. One of
consequences of this hypothesis is the conclusion that one of the reasons of
observed distinctions of parameters in MC and Ejecta can be fact that at
measurements of Ejecta the satellite passes further from the nose area of ICME,
than at measurements of MC. We also discuss the impact of Sheath in
magnetospheric activity and its contribution in estimation of Sun's open
magnetic flux.


title: Metastability for Glauber dynamics on random graphs

abstract:
  In this paper we study metastable behaviour at low temperature of Glauber
spin-flip dynamics on random graphs. We fix a large number of vertices and
randomly allocate edges according to the Configuration Model with a prescribed
degree distribution. Each vertex carries a spin that can point either up or
down. Each spin interacts with a positive magnetic field, while spins at
vertices that are connected by edges also interact with each other via a
ferromagnetic pair potential. We start from the configuration where all spins
point down, and allow spins to flip up or down according to a Metropolis
dynamics at positive temperature. We are interested in the time it takes the
system to reach the configuration where all spins point up. In order to achieve
this transition, the system needs to create a sufficiently large droplet of
up-spins, called critical droplet, which triggers the crossover.
  In the limit as the temperature tends to zero, and subject to a certain
\emph{key hypothesis} implying metastable behaviour, the average crossover time
follows the classical \emph{Arrhenius law}, with an exponent and a prefactor
that are controlled by the \emph{energy} and the \emph{entropy} of the critical
droplet. The crossover time divided by its average is exponentially
distributed. We study the scaling behaviour of the exponent as the number of
vertices tends to infinity, deriving upper and lower bounds. We also identify a
regime for the magnetic field and the pair potential in which the key
hypothesis is satisfied. The critical droplets, representing the saddle points
for the crossover, have a size that is of the order of the number of vertices.
This is because the random graphs generated by the Configuration Model are
expander graphs.


title:
Perturbation bounds and degree of imprecision for uniquely convergent
  imprecise Markov chains

abstract:
  The effect of perturbations of parameters for uniquely convergent imprecise
Markov chains is studied. We provide the maximal distance between the
distributions of original and perturbed chain and maximal degree of
imprecision, given the imprecision of the initial distribution. The bounds on
the errors and degrees of imprecision are found for the distributions at finite
time steps, and for the stationary distributions as well.


title: Rabi oscillations of two-photon states in nonlinear optical resonators

abstract:
  We demonstrate that four-wave mixing processes in high-quality non-linear
resonators can lead to Rabi-like oscillations in photon occupation numbers and
second-order correlation functions, being a characteristic feature of the
presence of entangled photon pairs in the optical signal. In the case of a
system driven by a continuous coherent pump, the oscillations occur in the
transient regime. We show that driving the system with pulsed coherent pumping
would generate strongly anti-bunched photon states.


title: Range-based argumentation semantics as 2-valued models

abstract:
  Characterizations of semi-stable and stage extensions in terms of 2-valued
logical models are presented. To this end, the so-called GL-supported and
GL-stage models are defined. These two classes of logical models are logic
programming counterparts of the notion of range which is an established concept
in argumentation semantics.


title:
Gravitational wave generation by interaction of high power lasers with
  matter using shock waves

abstract:
  Gravitational wave generation by a strong shock wave in the interaction of
high power laser with matter is analyzed in linear approximation of
gravitational theory. The analytical formulas and estimates are derived for the
metric perturbations and the radiated power of the generated gravitational
waves. Furthermore the characteristics of polarization and the behavior of test
particles are investigated in the presence of gravitational wave which will be
important for the detection.


title: Multi-Strangeness Production in Hadron Induced Reactions

abstract:
  We discuss in detail the formation and propagation of multi-strangeness
particles in reactions induced by hadron beams relevant for the forthcoming
experiments at FAIR. We focus the discussion on the production of the
decuplet-particle $\Omega$ and study for the first time the production and
propagation mechanism of this heavy hyperon inside hadronic environments. The
transport calculations show the possibility of $\Omega$-production in the
forthcoming \panda-experiment, which can be achieved with measurable
probabilities using high-energy secondary $\Xi$-beams. We predict cross
sections for $\Omega$-production. The theoretical results are important in
understanding the hyperon-nucleon and, in particular, the hyperon-hyperon
interactions also in the high-strangeness sector. We emphasize the importance
of our studies for the research plans at FAIR.


title: Computing Optical Properties of Ultra-thin Crystals

abstract:
  An overview is given of recent advances in experimental and theoretical
understanding of optical properties of ultra-thin crystal structures (graphene,
phosphorene, silicene, MoS2, MoSe2 , WS2 , WSe2 , h-AlN, h-BN, fluorographene,
graphane). Ultra-thin crystals are atomically-thick layered crystals that have
unique properties which differ from their 3D counterpart. Because of the
difficulties in the synthesis of few-atom-thick crystal structures, which are
thought to be the main building blocks of future nanotechnology, reliable
theoretical predictions of their electronic, vibrational and optical properties
are of great importance. Recent studies revealed the reliable predictive power
of existing theoretical approaches based on density functional theory (DFT).


title: On the Partition Dimension and the Twin Number of a Graph

abstract:
  A partition P of the vertex set of a connected graph G is a locating
partition of G if every vertex is uniquely determined by its vector of
distances to the elements of P. The partition dimension of G is the minimum
cardinality of a locating partition of G. A pair of vertices u,v of a graph G
are called twins if they have exactly the same set of neighbors other than u
and v. A twin class is a maximal set of pairwise twin vertices. The twin number
of a graph G is the maximum cardinality of a twin class of G.
  In this paper we undertake the study of the partition dimension of a graph by
also considering its twin number. This approach allows us to obtain the set of
connected graphs of order n having partition dimension n-2. This set is formed
by exactly 15 graphs, instead of 23, as was wrongly stated in the paper:
"Discrepancies between metric dimension and partition dimension of a connected
graph", published in Discrete Mathematics in 2008.


title:
QoS-Aware Joint Mode Selection and Channel Assignment for D2D
  Communications

abstract:
  Underlaying device-to-device (D2D) communications to a cellular network is
considered as a key technique to improve spectral efficiency in 5G networks.
For such D2D systems, mode selection and resource allocation have been widely
utilized for managing interference. However, previous works allowed at most one
D2D link to access the same channel, while mode selection and resource
allocation are typically separately designed. In this paper, we jointly
optimize the mode selection and channel assignment in a cellular network with
underlaying D2D communications, where multiple D2D links may share the same
channel. Meanwhile, the QoS requirements for both cellular and D2D links are
guaranteed, in terms of Signal-to-Interference-plus-Noise Ratio (SINR). We
first propose an optimal dynamic programming (DP) algorithm, which provides a
much lower computation complexity compared to exhaustive search and serves as
the performance bench mark. A bipartite graph based greedy algorithm is then
proposed to achieve a polynomial time complexity. Simulation results will
demonstrate the advantage of allowing each channel to be accessed by multiple
D2D links in dense D2D networks, as well as, the effectiveness of the proposed
algorithms.


title: SU(2) uncertainty limits

abstract:
  Although progress has been made recently in defining nontrivial uncertainty
limits for the SU(2) group, a description of the intermediate states bound by
these limits remains lacking. In this paper we enumerate possible uncertainty
relations for the SU(2) group that involve all three observables and that are,
moreover, invariant under SU(2) transformations. We demonstrate that these
relations however, even taken as a group, do not provide sharp, saturable
bounds. To find sharp bounds, we systematically calculate the variance of the
SU(2) operators for all pure states belonging to the $N=2$ and $N=3$
polarisation excitation manifold (corresponding to spin 1 and spin 3/2).
Lastly, and perhaps counter to expectation, we note that even pure states can
reach the maximum uncertainty limit.


title: Model Reduction for Multiscale Lithium-Ion Battery Simulation

abstract:
  In this contribution we are concerned with efficient model reduction for
multiscale problems arising in lithium-ion battery modeling with spatially
resolved porous electrodes. We present new results on the application of the
reduced basis method to the resulting instationary 3D battery model that
involves strong non-linearities due to Buttler-Volmer kinetics. Empirical
operator interpolation is used to efficiently deal with this issue.
Furthermore, we present the localized reduced basis multiscale method for
parabolic problems applied to a thermal model of batteries with resolved porous
electrodes. Numerical experiments are given that demonstrate the reduction
capabilities of the presented approaches for these real world applications.


title:
Inflationary universe in a conformally-invariant two scalar-field theory
  with an $R^2$ term

abstract:
  We investigate the inflationary universe in a theory where two scalar fields
non-minimally coupling to the scalar curvature and an extra $R^2$ term exist
and the conformal invariance is broken. In particular, the slow-roll inflation
is explored for the case that one scalar field is dynamical and that two scalar
fields are dynamical. As a result, we show that the spectral index of the
curvature perturbations and the tensor-to-scalar ratio of the density
perturbations can be compatible with the Planck results. It is also
demonstrated that the graceful exit from inflation can be realized.


title: Extending Finite Memory Determinacy to Multiplayer Games

abstract:
  We show that under some general conditions the finite memory determinacy of a
class of two-player win/lose games played on finite graphs implies the
existence of a Nash equilibrium built from finite memory strategies for the
corresponding class of multi-player multi-outcome games. This generalizes a
previous result by Brihaye, De Pril and Schewe. We provide a number of example
that separate the various criteria we explore.
  Our proofs are generally constructive, that is, provide upper bounds for the
memory required, as well as algorithms to compute the relevant Nash equilibria.


title:
X-ray experiment provides a way to reveal the distinction between
  discrete and continuous conformation of myosin head

abstract:
  The corner stone of the classical model after Huxley and Simmons is
supposition that a myosin head can reside only in several discrete states and
irregularly jumps from one state to another. Until now, it has not been found a
way to experimentally verify this supposition although confirmation or
refutation of the existence of discrete states is crucial for the solution of
myosin motor problem. Here I show that a set of equal myosin heads arranged
equidistantly along an actin filament produce X-ray pattern which varies with
the type of conformation. If the lever arms of all myosin heads reside in one
and the same position (continuous conformation), all the heads have the same
form-factor and equally scatter electromagnetic wave. In this case, only the
geometric factor associated with a spatial ordering of the heads will determine
the X-ray pattern. The situation changes if the average lever arm position is
the same, but inherently every head can reside only in several diverse discrete
states, hopping irregularly from one to another. In this case, the form-factors
corresponding to distinct states are dissimilar, and the increments in phases
of X-rays scattered by different heads are different as well. Inasmuch as every
quantum of radiation interacts with the heads residing in different states,
this results in additional interference and some peaks in the X-ray pattern
should slacken or even extinct as compared with the pattern from the heads with
the continuous-type conformation. The formulas describing both cases are
compared in this article. In general, the distinction between X-ray patterns is
insignificant, but they could be appreciably different at some stages of
conformation process (respective lever arm position depends on the type of
discrete model). Consequently, one can with luck attempt to find out this
difference using a high-sensitive equipment.


title: Noether symmetries and duality transformations in cosmology

abstract:
  We discuss the relation between Noether (point) symmetries and discrete
symmetries for a class of minisuperspace cosmological models. We show that when
a Noether symmetry exists for the gravitational Lagrangian then there exists a
coordinate system in which a reversal symmetry exists. Moreover as far as
concerns the scale-factor duality symmetry of the dilaton field, we show that
it is related to the existence of a Noether symmetry for the field equations,
and the reversal symmetry in the normal coordinates of the symmetry vector
becomes scale-factor duality symmetry in the original coordinates. In
particular the same point symmetry as also the same reversal symmetry exists
for the Brans-Dicke- scalar field with linear potential while now the discrete
symmetry in the original coordinates of the system depends on the Brans-Dicke
parameter and it is a scale-factor duality when $\omega_{BD}=1$. Furthermore,
in the context of the O'Hanlon theory for $f\left( R\right) $-gravity, it is
possible to show how a duality transformation in the minisuperspace can be used
to relate different gravitational models.


title:
Ground-state phases of the spin-1 $J_{1}$--$J_{2}$ Heisenberg
  antiferromagnet on the honeycomb lattice

abstract:
  We study the zero-temperature quantum phase diagram of a spin-1 Heisenberg
antiferromagnet on the honeycomb lattice with both nearest-neighbor exchange
coupling $J_{1}>0$ and frustrating next-nearest-neighbor coupling $J_{2} \equiv
\kappa J_{1} > 0$, using the coupled cluster method implemented to high orders
of approximation, and based on model states with different forms of classical
magnetic order. For each we calculate directly in the bulk thermodynamic limit
both ground-state low-energy parameters (including the energy per spin,
magnetic order parameter, spin stiffness coefficient, and zero-field uniform
transverse magnetic susceptibility) and their generalized susceptibilities to
various forms of valence-bond crystalline (VBC) order, as well as the energy
gap to the lowest-lying spin-triplet excitation. In the range $0 < \kappa < 1$
we find evidence for four distinct phases. Two of these are quasiclassical
phases with antiferromagnetic long-range order, one with 2-sublattice N\'{e}el
order for $\kappa < \kappa_{c_{1}} = 0.250(5)$, and another with 4-sublattice
N\'{e}el-II order for $\kappa > \kappa_{c_{2}} = 0.340(5)$. Two different
paramagnetic phases are found to exist in the intermediate region. Over the
range $\kappa_{c_{1}} < \kappa < \kappa^{i}_{c} = 0.305(5)$ we find a gapless
phase with no discernible magnetic order, which is a strong candidate for being
a quantum spin liquid, while over the range $\kappa^{i}_{c} < \kappa <
\kappa_{c_{2}}$ we find a gapped phase, which is most likely a lattice nematic
with staggered dimer VBC order that breaks the lattice rotational symmetry.


title:
Decoding the $X(5568)$ as a fully open-flavor $su\bar b\bar d$
  tetraquark state

abstract:
  We investigate the recent evidence for a charged $X(5568)$ meson as an exotic
open-flavor tetraquark state $su\bar b\bar d$ with $J^P=0^+/1^+$ in the
framework of QCD sum rules. We use the color antisymmetric $[\mathbf{\bar
3_c}]_{su} \otimes [\mathbf{3_c}]_{\bar{b}\bar d}$ tetraquark currents in both
scalar and axial-vector channels to perform evaluations and numerical analyses.
Our results imply that the $X(5568)$ can be interpreted as both the scalar
$su\bar b\bar d$ tetraquark state and the axial-vector one, which are in good
agreement with the experimental measurement. We also discuss the possible decay
patterns of the $X(5568)$ and suggest to search for its neutral partner in the
radiative decay into $B_s^0 \gamma$ and $B_s^* \gamma$, which can be used to
determine its spin-parity quantum numbers. Moreover, we predict its charmed
partner state around $2.55$ GeV with the quark content $su\bar c\bar d$ and
$J^P=0^+/1^+$.


title: SU(3) Approach to Hypernuclear Interactions and Spectroscopy

abstract:
  The $SU(3)$ meson exchange approach to interactions within the baryon octet
and nuclear density functional theory are used to derive an \emph{ab initio}
description of hypernuclear interactions. The density dependence of
interactions is recast into a DFT with density dependent interaction vertices.
The field-theoretical structure is retained by expressing the vertices as
functionals of the matter field operators. Applications to infinite hypermatter
and neutron star matter are discussed. A new approach is presented allowing to
determine in-medium coupling constants out of the $NN$-vertex functionals,
obtained e.g. by DBHF theory, for the full baryon octet by exploiting $SU(3)$
relations.


title:
Semileptonic decays of $B_c$ meson to S-wave charmonium states in the
  perturbative QCD approach

abstract:
  Inspired by the recent measurement of the ratio of $B_c$ branching fractions
to $J/\psi \pi^+$ and $J/\psi \mu^+\nu_{\mu}$ final states at the LHCb
detector, we study the semileptonic decays of $B_c$ meson to the S-wave ground
and radially excited 2S and 3S charmonium states with the perturbative QCD
approach. After evaluating the form factors for the transitions $B_c\rightarrow
P,V$, where $P$ and $V$ denote pseudoscalar and vector S-wave charmonia,
respectively, we calculate the branching ratios for all these semileptonic
decays. The theoretical uncertainty of hadronic input parameters are reduced by
utilizing the light-cone wave function for $B_c$ meson. It is found that the
predicted branching ratios range from $10^{-6}$ up to $10^{-2}$ and could be
measured by the future LHCb experiment. Our prediction for the ratio of
branching fractions $\frac{\mathcal {BR}(B_c^+\rightarrow J/\Psi
\pi^+)}{\mathcal {BR}(B_c^+\rightarrow J/\Psi \mu^+\nu_{\mu})}$ is in good
agreement with the data. For $B_c\rightarrow V l \nu_l$ decays, the relative
contributions of the longitudinal and transverse polarization are discussed in
different momentum transfer squared regions. These predictions will be tested
on the ongoing and forthcoming experiments.


title:
Entanglement concentration of microwave photons based on Kerr effect in
  circuit QED

abstract:
  In recent years, superconducting qubits show great potential in quantum
computation. Hence, microwave photons become very interesting qubits for
quantum information processing assisted by superconducting quantum computation.
Here, we present the first protocol for the entanglement concentration on
microwave photons, resorting to the cross-Kerr effect in circuit quantum
electrodynamics (QED). Two superconducting transmission line resonators (TLRs)
coupled to superconducting molecule with the N-type level structure induce the
effective cross-Kerr effect for realizing the quantum nondemolition (QND)
measurement on microwave photons. With this device, we present a two-qubit
polarization parity QND detector on the photon states of the superconducting
TLRs, which can be used to concentrate efficiently the nonlocal non-maximally
entangled states of microwave photons assisted by several linear microwave
elements. This protocol has a high efficiency and it may be useful for
solid-state quantum information processing assisted by microwave photons.


title:
Calibrating conservative and dissipative response of electrically-driven
  quartz tuning forks

abstract:
  Determining sensor parameters is a prerequisite for quantitative force
measurement. Here we report a direct, high-precision calibration method for
quartz tuning fork(TF) sensors that are popular in the feld of nanomechanical
measurement. In the method, conservative and dissipative forces with controlled
amplitudes are applied to one prong of TF directly to mimic the tip-sample
interaction, and the responses of the sensor are measured at the same time to
extract sensor parameters. The method, for the frst time, allows force gradient
and damping coeffcient which correspond to the conservative and dissipative
interactions to be measured simultaneously. The calibration result shows
surprisingly that, unlike cantilevers, the frequency shift for TFs depends on
both the conservative and dissipative forces, which may be ascribed to the
complex dynamics. The effectiveness of the method is testifed by force spectrum
measurement with a calibrated TF. The method is generic for all kinds of
sensors used for non-contact atomic force microscopy(NC-AFM) and is an
important improvement for quantitative nanomechanical measurement.


title:
Effect of the electromagnetic environment on current fluctuations in
  driven tunnel junctions

abstract:
  We examine current fluctuations in tunnel junctions driven by a superposition
of a constant and a sinusoidal voltage source. In standard setups the external
voltage is applied to the tunneling element via an impedance providing an
electromagnetic environment of the junction. The modes of this environment are
excited by the time-dependent voltage and are the source of Johnson-Nyquist
noise. We determine the autocorrelation function of the current flowing in the
leads of the junction in the weak tunneling limit up to terms of second order
in the tunneling Hamiltonian. The driven modes of the electromagnetic
environment are treated exactly by means of a unitary transformation introduced
recently. Particular emphasis is placed on the spectral function of the current
fluctuations. The spectrum is found to comprise three contributions: a term
arising from the Johnson-Nyquist noise of the environmental impedance, a part
due to the shot noise of the tunneling element and a third contribution which
comes from the cross-correlation between fluctuations caused by the
electromagnetic environment and fluctuations of the tunneling current. All
three parts of the spectral function occur already for devices under dc bias.
The spectral function of ac driven tunneling elements can be determined from
the result for a dc bias by means of a photo-assisted tunneling relation of the
Tien-Gordon type. Specific results are given for an Ohmic environment and for a
junction driven through a resonator.


title:
Sign changes of fourier coefficients of modular forms of half integral
  weight, 2

abstract:
  In this paper, we investigate the sign changes of Fourier coefficients of
half-integral weight Hecke eigenforms and give two quantitative results on the
number of sign changes.


title: Nonlinear $O(3)$ sigma model in discrete complex analysis

abstract:
  We present an exact discrete nonlinear $O(3)$ sigma model defined on
two-dimensional lattices using Mercat's discrete complex analysis and its
elaboration by Bobenko and G\"unther. We define a weighted discrete Dirichlet
energy and area on the medial graph of a planar quad-graph and derive an
inequality between these quantities. We write $f$ for the complex function
obtained from the unit vector field of the model and the stereographic
projection. The inequality is saturated if and only if the $f$ is discrete
(anti-)holomorphic. By means of a weight $W$ derived from a kind of tiling of
the sphere $S^2$, the weighted discrete area ${\cal A}^{W}_{\diamondsuit}(f)$
admits a geometrical interpretation, namely, ${\cal A}^{W}_{\diamondsuit}(f)=4
\pi N $ for a topological quantum number $N \in \pi_2(S^2)$. This ensures the
topological stability of the solutions. For quad-graphs with orthogonal
diagonals, we show that the discrete (anti-)holomorphic function $f$ satisfies
the Euler--Lagrange equation derived from the weighted discrete Dirichlet
energy. On a rhombic lattice, the weighted discrete Dirichlet energy, area, and
Euler--Lagrange equation tend to their continuum forms as the lattice spacings
tend to zero. On a polar lattice, the weighted discrete area is expressed as a
$q$-integral.


title:
On Fourier coefficients of modular forms of half integral weight at
  squarefree integers

abstract:
  We show that the Dirichlet series associated to the Fourier coefficients of a
half-integral weight Hecke eigenform at squarefree integers extends
analytically to a holomorphic function in the half-plane $\re
s\textgreater{}\tfrac{1}{2}$. This exhibits a high fluctuation of the
coefficients at squarefree integers.


title: A hierarchy of local decision

abstract:
  We extend the notion of distributed decision in the framework of distributed
network computing, inspired by recent results on so-called distributed graph
automata. We show that, by using distributed decision mechanisms based on the
interaction between a prover and a disprover, the size of the certificates
distributed to the nodes for certifying a given network property can be
drastically reduced. For instance, we prove that minimum spanning tree can be
certified with $O(\log n)$-bit certificates in $n$-node graphs, with just one
interaction between the prover and the disprover, while it is known that
certifying MST requires $\Omega(\log^2 n)$-bit certificates if only the prover
can act. The improvement can even be exponential for some simple graph
properties. For instance, it is known that certifying the existence of a
nontrivial automorphism requires $\Omega(n^2)$ bits if only the prover can act.
We show that there is a protocol with two interactions between the prover and
the disprover enabling to certify nontrivial automorphism with $O(\log n)$-bit
certificates. These results are achieved by defining and analysing a local
hierarchy of decision which generalizes the classical notions of
proof-labelling schemes and locally checkable proofs.


title:
Tunable magnetic anisotropy from higher-harmonics exchange scattering on
  the surface of a topological insulator

abstract:
  We show that higher-harmonics exchange scattering from a magnetic adatom on
the surface of a three dimensional topological insulator leads to a magnetic
anisotropy whose magnitude and sign may be tuned by adjusting the chemical
potential of the helical surface band. As chemical potential moves from the
Dirac point towards the surface band edge, the surface normal is found to
change from magnetic easy, to hard axis. Hexagonal warping is shown to diminish
the region with easy axis anisotropy, and to suppress the anisotropy
altogether. This indirect contribution can be comparable in magnitude to the
intrinsic term arising from crystal field splitting and atomic spin-orbit
coupling, and its tunability with chemical potential makes the two
contributions experimentally discernible, and endows this source of anisotropy
with potentially interesting magnetic functionality.


title: High-Dimensional $L_2$Boosting: Rate of Convergence

abstract:
  Boosting is one of the most significant developments in machine learning.
This paper studies the rate of convergence of $L_2$Boosting, which is tailored
for regression, in a high-dimensional setting. Moreover, we introduce so-called
\textquotedblleft post-Boosting\textquotedblright. This is a post-selection
estimator which applies ordinary least squares to the variables selected in the
first stage by $L_2$Boosting. Another variant is \textquotedblleft Orthogonal
Boosting\textquotedblright\ where after each step an orthogonal projection is
conducted. We show that both post-$L_2$Boosting and the orthogonal boosting
achieve the same rate of convergence as LASSO in a sparse, high-dimensional
setting. We show that the rate of convergence of the classical $L_2$Boosting
depends on the design matrix described by a sparse eigenvalue constant. To show
the latter results, we derive new approximation results for the pure greedy
algorithm, based on analyzing the revisiting behavior of $L_2$Boosting. We also
introduce feasible rules for early stopping, which can be easily implemented
and used in applied work. Our results also allow a direct comparison between
LASSO and boosting which has been missing from the literature. Finally, we
present simulation studies and applications to illustrate the relevance of our
theoretical results and to provide insights into the practical aspects of
boosting. In these simulation studies, post-$L_2$Boosting clearly outperforms
LASSO.

categories: stat.ML cs.LG econ.EM math.ST stat.ME stat.TH


title:
Aperiodic order and spherical diffraction, I: Auto-correlation of model
  sets

abstract:
  We study uniform and non-uniform model sets in arbitrary locally compact
second countable (lcsc) groups, which provide a natural generalization of
uniform model sets in locally compact abelian groups as defined by Meyer and
used as mathematical models of quasi-crystals. We then define a notion of
auto-correlation for subsets of finite local complexitiy in arbitrary lcsc
groups, which generalizes Hof's classical definition beyond the class of
amenable groups, and provide a formula for the auto-correlation of a regular
model set. Along the way we show that the punctured hull of an arbitrary
regular model set admits a unique invariant probability measure, even in the
case where the punctured hull is non-compact and the group is non-amenable. In
fact this measure is also the unique stationary measure with respect to any
admissible probability measure.


title:
All-mechanical quantum noise cancellation for accelerometry: broadband
  with momentum measurements, narrow band without

abstract:
  We show that the ability to make direct measurements of momentum, in addition
to the usual direct measurements of position, allows a simple configuration of
two identical mechanical oscillators to be used for broadband back-action-free
force metrology. This would eliminate the need for an optical reference
oscillator in the scheme of Tsang and Caves [Phys. Rev. Lett. 105, 123601
(2010)], along with its associated disadvantages. We also show that if one is
restricted to position measurements alone then two copies of the same
two-oscillator configuration can be used for narrow-band back-action-free force
metrology.


title: Magnetic Fields in Massive Stars: New Insights

abstract:
  Substantial progress has been achieved over the last decade in studies of
stellar magnetism due to the improvement of magnetic field measurement methods.
We review recent results on the magnetic field characteristics of early B- and
O-type stars obtained by various teams using different measurement techniques.


title: Infinite horizon sparse optimal control

abstract:
  A class of infinite horizon optimal control problems involving $L^p$-type
cost functionals with $0<p\leq 1$ is discussed. The existence of optimal
controls is studied for both the convex case with $p=1$ and the nonconvex case
with $0<p<1$, and the sparsity structure of the optimal controls promoted by
the $L^p$-type penalties is analyzed. A dynamic programming approach is
proposed to numerically approximate the corresponding sparse optimal
controllers.


title:
The kinetic Sunyaev-Zel'dovich tomography II: probing the circumgalactic
  medium

abstract:
  We propose the use of the kinetic Sunyaev-Zel'dovich (kSZ) effect to probe
the circumgalactic medium (CGM), with the aid of a spectroscopic survey
covering the same area of a SZ survey. One can design an optimal estimator of
the kSZ effect of the CGM with a matched filter, and construct the cross
correlation between the estimator and the peculiar velocity recovered from the
galaxy survey, which can be measured by stacking a number of galaxies. We
investigate two compelling profiles for the CGM, the MB profile (Maller &
Bullock 2004) and the $\beta$ profile, and estimate the detectability against
the synergy of a fiducial galaxy survey with number density $10^{-3}h^3\,$
Mpc$^{-3}$ and an ACT-like SZ survey. We show that the shape of the filter does
not change much with redshift for the $\beta$ profile, while there are
significant side lobes at $z<0.1$ for the MB profile. By stacking $\sim 10^4$
Milky Way-size halos around z $\sim 0.5$, one can get $\gtrsim$ 1 $\sigma$
signal to noise (S/N) for the both profiles. The S/N increases with decreasing
redshift before it reaches a maximum ($\sim$ 7.5 at z $\simeq$ 0.15 for the MB
profile, $\sim 19$ at $z\simeq 0.03$ for the $\beta$ profile). Due to the large
beam size, a Planck-like CMB survey can marginally detect the kSZ signal by
stacking the same number of galaxies at $z<0.1$. The search for the CGM in
realistic surveys will involve dividing the galaxies into subsamples with
similar redshift and mass of host halos, and scaling the results presented here
to obtain the S/N.


title: Tailoring Magnetic Frustration in Strained Epitaxial FeRh Films

abstract:
  We report on a strain-induced martensitic transformation, accompanied by a
suppression of magnetic order in epitaxial films of chemically disordered FeRh.
X-ray diffraction, transmission electron microscopy and electronic structure
calculations reveal that the lowering of symmetry (from cubic to tetragonal)
imposed by the epitaxial relation leads to a further, unexpected,
tetragonal-to-orthorhombic transition, triggered by a band-Jahn-Teller-type
lattice instability. The collapse of magnetic order is a direct consequence of
this structural change, which upsets the subtle balance between ferromagnetic
nearest-neighbor interactions arising from Fe-Rh hybridization and frustrated
antiferromagnetic coupling among localized Fe moments at larger distances.


title:
Growth of torsion of elliptic curves with full 2-torsion over quadratic
  cyclotomic fields

abstract:
  Let $K = \mathbb{Q}(\sqrt{-3})$ or $\mathbb{Q}(\sqrt{-1})$ and let $C_n$
denote the cyclic group of order $n$. We study how the torsion part of an
elliptic curve over $K$ grows in a quadratic extension of $K$. In the case
$E(K)[2] \approx C_2 \oplus C_2$ we determine how a given torsion structure can
grow in a quadratic extension and the maximum number of quadratic extensions in
which it grows. We also classify the torsion structures which occur as the
quadratic twist of a given torsion structure.


title:
Atomic structure of metal-halide perovskites from first principles: The
  chicken-and-egg paradox of the organic-inorganic interaction

abstract:
  We have studied the prototype hybrid organic-inorganic perovskite CH3NH3PbI3
and its three close relatives, CH3NH3SnI3, CH3NH3PbCl3 and CsPbI3, using
relativistic density function theory. The long-range van der Waals (vdW)
interactions were incorporated into the Perdew-Burke-Ernzerhof (PBE)
exchange-correlation functional using the Tkatchenko-Scheffler pairwise scheme.
Our results reveal that hydrogen bonding, which is well described by the PBE
functional, plays a decisive role for the structural parameters of these
systems, including the position and orientation of the organic cation as well
as the deformation of the inorganic framework. The magnitude of the
inorganic-framework deformation depends sensitively on the orientation of the
organic cation, and directly influences the stability of the hybrid
perovskites. Our results suggest that the organic and the inorganic components
complement each other: The low symmetry of the organic cation is the origin of
the inorganic-framework deformation, which then aids the overall stabilization
of the hybrid perovskite structure. This stabilization is indirectly affected
by vdW interactions, which lead to smaller unit-cell volumes than in PBE and
therefore modulate the interaction between the organic cation and the inorganic
framework. The vdW-induced lattice-constant corrections are system dependent
and lead to PBE+vdW lattice constants in good agreement with experiment.
Further insight is gained by analysing the vdW contributions. In all
iodide-based hybrid perovskites the interaction between the organic cation and
the iodide anions provides the largest lattice-constant change, followed by
iodine-iodine and the organic cation - heavy-metal cation interaction. These
corrections follow an almost linear dependence on the lattice constant within
the range considered in our study, and are therefore approximately additive.


title: Universality in cuprates: a gauge approach

abstract:
  In high-$T_c$ cuprates many quantities exhibit a non-Fermi liquid
universality hinting at a very peculiar structure of the underlying pairing
mechanism for superconductivity: in this work we focus on the universality for
the in-plane resistivity and for the superfluid density.
  We outline the previously developed spin-charge gauge approach to
superconductivity in hole-doped cuprates: we decompose the hole of the $t-t'-J$
model for the $\mathrm{Cu}\mathrm{O}_2$ planes as the product of a spinful,
chargeless gapped spinon and of a spinless, charged holon with Fermi surface.
Each one of these particle excitations is bound to a statistical gauge flux,
allowing one to optimize their statistics.
  We show that this model allows for a natural interpretation of the
universality: within this approach, under suitable conditions, the spinonic and
holonic contributions to a response function sum up according to a Ioffe-Larkin
rule. We argue that, if the spinonic contribution dominates, then one should
expect strongly non-Fermi-liquid-like universality, due to the insensitivity of
spinons to Fermi surface details. The in-plane resistivity and superfluid
density are indeed dominated by the spinons in the underdoped region. We
theoretically derive these quantities, discussing their universal behaviours
and comparing them with experimental data.


title: On the multiple zeros of a partial theta function

abstract:
  We consider the partial theta function $\theta
(q,x):=\sum_{j=0}^{\infty}q^{j(j+1)/2}x^j$, where $x\in \mathbb{C}$ is a
variable and $q\in \mathbb{C}$, $0<|q|<1$, is a parameter. We show that, for
any fixed $q$, if $\zeta$ is a multiple zero of the function $\theta (q,.)$,
then $|\zeta |\leq 8^{11}$.


title:
Clustering coefficient of random intersection graphs with infinite
  degree variance

abstract:
  For a random intersection graph with a power law degree sequence having a
finite mean and an infinite variance we show that the global clustering
coefficient admits a tunable asymptotic distribution.


title: A Complex-Network Perspective on Alexander's Wholeness

abstract:
  The wholeness, conceived and developed by Christopher Alexander, is what
exists to some degree or other in space and matter, and can be described by
precise mathematical language. However, it remains somehow mysterious and
elusive, and therefore hard to grasp. This paper develops a complex network
perspective on the wholeness to better understand the nature of order or beauty
for sustainable design. I bring together a set of complexity-science subjects
such as complex networks, fractal geometry, and in particular underlying
scaling hierarchy derived by head/tail breaks - a classification scheme and a
visualization tool for data with a heavy-tailed distribution, in order to make
Alexander's profound thoughts more accessible to design practitioners and
complexity-science researchers. Through several case studies (some of which
Alexander studied), I demonstrate that the complex-network perspective helps
reduce the mystery of wholeness and brings new insights to Alexander's thoughts
on the concept of wholeness or objective beauty that exists in fine and deep
structure. The complex-network perspective enables us to see things in their
wholeness, and to better understand how the kind of structural beauty emerges
from local actions guided by the 15 fundamental properties, and by
differentiation and adaptation processes. The wholeness goes beyond current
complex network theory towards design or creation of living structures.
  Keywords: Theory of centers, living geometry, Christopher Alexander,
head/tail breaks, and beauty