title:
Lattice Boltzmann Scheme associated with flexible Prandtl number and
  specific heat ratio based on the polyatomic ES-BGK model

abstract:
  A lattice Boltzmann scheme associated with flexible Prandtl number and
specific heat ratio is proposed, which is based on the polyatomic ellipsoidal
statistics model(ES-BGK). The Prandtl number can be modified by a parameter of
the Gaussian distribution and the specific heat ratio can be modified by
additional free degrees. For the sake of constructing the scheme proposed, the
Gaussian distribution is expanded on the Hermite polynomials and the general
term formula for the Hermite coefficients of the Gaussian distribution is
deduced. Benchmarks are carried out to verify the scheme proposed. The
numerical results are in good agreement with the the analytical solutions.


title:
Algebraic Lipschitz and Subdifferential Calculus in General Vector
  Spaces

abstract:
  The main contribution of this paper is that every convex function with
non-empty relative algebraic interior of its domain is Lipschitz and
subdifferentiable in some algebraic sense without any additional topological
constraints. The proposed approach uses slightly modified Clarke's
subdifferential for functions defined on a convex symmetric set and Lipschitz
with respect to a Minkowski functional. Following this, Clarke's
subdifferential calculus is generalized to vector spaces and, where continuity
properties are claimed, to topological vector spaces.


title:
Topological susceptibility in finite temperature (2+1)-flavor QCD using
  gradient flow

abstract:
  We compute the topological charge and its susceptibility in finite
temperature (2+1)-flavor QCD on the lattice applying a gradient flow method.
With the Iwasaki gauge action and nonperturbatively $O(a)$-improved Wilson
quarks, we perform simulations on a fine lattice
with~$a\simeq0.07\,\mathrm{fm}$ at a heavy $u$, $d$ quark mass with
$m_\pi/m_\rho\simeq0.63$ but approximately physical $s$ quark mass with
$m_{\eta_{ss}}/m_\phi\simeq0.74$. In a temperature range
from~$T\simeq174\,\mathrm{MeV}$ ($N_t=16$) to $697\,\mathrm{MeV}$ ($N_t=4$), we
study two topics on the topological susceptibility. One is a comparison of
gluonic and fermionic definitions of the topological susceptibility. Because
the two definitions are related by chiral Ward-Takahashi identities, their
equivalence is not trivial for lattice quarks which violate the chiral symmetry
explicitly at finite lattice spacings. The gradient flow method enables us to
compute them without being bothered by the chiral violation. We find a good
agreement between the two definitions with Wilson quarks. The other is a
comparison with a prediction of the dilute instanton gas approximation, which
is relevant in a study of axions as a candidate of the dark matter in the
evolution of the Universe. We find that the topological susceptibility shows a
decrease in $T$ which is consistent with the predicted $\chi_\mathrm{t}(T)
\propto (T/T_{\rm pc})^{-8}$ for three-flavor QCD even at low temperature
$T_{\rm pc} < T\le1.5 T_{\rm pc}$.


title: Modularity promotes epidemic recurrence

abstract:
  The long-term evolution of epidemic processes depends crucially on the
structure of contact networks. As empirical evidence indicates that human
populations exhibit strong community organization, we investigate here how such
mesoscopic configurations affect the likelihood of epidemic recurrence. Through
numerical simulations on real social networks and theoretical arguments using
spectral methods, we demonstrate that highly contagious diseases that would
have otherwise died out rapidly can persist indefinitely for an optimal range
of modularity in contact networks.


title: Temperature dependence of topological susceptibility using gradient flow

abstract:
  We study temperature dependence of the topological susceptibility with the
$N_{f}=2+1$ flavors Wilson fermion. We have two major interests in this paper.
One is a comparison of gluonic and fermionic definitions of the topological
susceptibility. Two definitions are related by the chiral Ward-Takahashi
identity but their coincidence is highly non-trivial for the Wilson fermion. By
applying the gradient flow both for the gauge and quark fields we find a good
agreement of these two measurements. The other is a verification of a
prediction of the dilute instanton gas approximation at low temperature region
$T_{pc}< T<1.5T_{pc}$, for which we confirm the prediction that the topological
susceptibility decays with power $\chi_{t}\propto(T/T_{pc})^{-8}$ for three
flavors QCD.


title:
A 2.5-dimensional viscous, resistive, advective magnetized
  accretion-outflow coupling in black hole systems: A higher order polynomial
  approximation. I

abstract:
  The correlated and coupled dynamics of accretion and outflow around black
holes (BHs) are essentially governed by the fundamental laws of conservation as
outflow extracts matter, momentum and energy from the accretion region. Here we
analyzed a robust form of 2.5-dimensional viscous, resistive, advective
magnetized accretion-outflow coupling in BH systems, in the mean field
magnetohydrodynamical (MHD) regime. We solve the complete set of coupled MHD
conservation equations self-consistently, through invoking a generalized
polynomial expansion in two dimensions. We perform a critical analysis of
accretion-outflow region and provide a complete quasi-analytical family of
solutions for advective flows. We obtain the physical plausible outflow
solutions at high turbulent viscosity parameter $\alpha \, (\ge 0.3)$, and at a
reduced scale-height, as magnetic stresses compress or squeeze the flow region.
We found that the value of the large-scale poloidal magnetic field $\bar B_P$
is enhanced with increasing geometrical thickness of the accretion flow. On the
other hand differential magnetic torque ($-r^2 \bar B_{\varphi} \bar B_z$)
increases with the increase in $\dot M$. $\bar B_P$, $-r^2 \bar B_{\varphi}
\bar B_z$ as well as the plasma beta $\beta_P$ get strongly augmented with the
increase in the value of $\alpha$, enhancing the transport of vertical flux
outwards. Our solutions indicate that magnetocentrifugal acceleration plausibly
plays a dominant role in effusing out plasma from the radial accretion flow in
moderately advective paradigm which are more centrifugally dominated, however
in strongly advective paradigm it is likely that the thermal pressure gradient
would play a more contributory role in the vertical transport of the plasma.


title: Time-resolved spectroscopy with entangled photons

abstract:
  Interaction of light with media often occurs with a femtosecond response
time. Its measurement by conventional techniques requires the use of
femtosecond lasers and sophisticated time-gated optical detection1-3. Here we
demonstrate that by exploiting quantum interference of entangled photons it is
possible to measure the phase relaxation time of a media on the femtosecond
time scale (down to 100 fs) using accessible continuous wave laser and
single-photon counting. We insert the sample in the Hong-Ou-Mandel
interferometer4 and infer the phase relaxation time from the modification of
the two-photon interference pattern. In addition to its simplicity and ease of
use, the technique does not require compensation of group velocity
dispersion5-8 and does not induce photo-damage of the samples. This technique
will be useful for characterization of ultrafast phase relaxation processes in
material science, chemistry, and biology.


title:
An Efficient Approach to Boosting Performance of Deep Spiking Network
  Training

abstract:
  Nowadays deep learning is dominating the field of machine learning with
state-of-the-art performance in various application areas. Recently, spiking
neural networks (SNNs) have been attracting a great deal of attention, notably
owning to their power efficiency, which can potentially allow us to implement a
low-power deep learning engine suitable for real-time/mobile applications.
However, implementing SNN-based deep learning remains challenging, especially
gradient-based training of SNNs by error backpropagation. We cannot simply
propagate errors through SNNs in conventional way because of the property of
SNNs that process discrete data in the form of a series. Consequently, most of
the previous studies employ a workaround technique, which first trains a
conventional weighted-sum deep neural network and then maps the learning
weights to the SNN under training, instead of training SNN parameters directly.
In order to eliminate this workaround, recently proposed is a new class of SNN
named deep spiking networks (DSNs), which can be trained directly (without a
mapping from conventional deep networks) by error backpropagation with
stochastic gradient descent. In this paper, we show that the initialization of
the membrane potential on the backward path is an important step in DSN
training, through diverse experiments performed under various conditions.
Furthermore, we propose a simple and efficient method that can improve DSN
training by controlling the initial membrane potential on the backward path. In
our experiments, adopting the proposed approach allowed us to boost the
performance of DSN training in terms of converging time and accuracy.


title:
Regular continuum systems of point particles. I: systems without
  interaction

abstract:
  Normally, in mathematics and physics, only point particle systems, which are
either finite or countable, are studied. We introduce new formal mathematical
object called regular continuum system of point particles (with continuum
number of particles). Initially, each particle is characterized by the pair:
(initial coordinate, initial velocity) in $R^{2d}$. Moreover, all initial
coordinates are different and fill up some domain in $R^{d}$. Each particle
moves via normal Newtonian dynamics under influence of some external force, but
there is no interaction between particles. If the external force is bounded
then trajectories of any two particles in the phase space do not intersect.
More exactly, at any time moment any two particles have either different
coordinates or different velocities. The system is called regular if there are
no particle collisions in the coordinate space.
  The regularity condition is necessary for the velocity of the particle,
situated at a given time at a given space point, were uniquely defined. Then
the classical Euler equation for the field of velocities has rigorous meaning.
Though the continuum of particles is in fact a continuum medium, the crucial
notion of regularity was not studied in mathematical literature.
  It appeared that the seeming simplicity of the object (absence of
interaction) is delusive. Even for simple external forces we could not find
simple necessary and sufficient regularity conditions. However, we found a rich
list of examples, one-dimensional and mufti-dimensional, where we could get
regularity conditions on different time intervals. In conclusion we formulate
many unsolved problems for regular systems with interaction.


title:
Modelling and simulation of large-scale polarized dust emission over the
  southern Galactic cap using the GASS HI data

abstract:
  The Planck survey has quantified polarized Galactic foregrounds and
established that they are a main limiting factor in the quest for the cosmic
microwave background (CMB) B-mode signal induced by primordial gravitational
waves during cosmic inflation. Accurate separation of the Galactic foregrounds
therefore binds this quest to our understanding of the magnetized interstellar
medium (ISM). The two most relevant empirical results from analysis of Planck
data are line of sight depolarization arising from fluctuations of the Galactic
magnetic field orientation and alignment of filamentary dust structures with
the magnetic field at high Galactic latitude. Furthermore, Planck and HI
emission data in combination indicate that most of the filamentary dust
structures are in the cold neutral medium. The goal of this paper is to test
whether these salient observational results, taken together, can account fully
for the statistical properties of the dust polarization over a selected low
column density region comprising 34 % of the southern Galactic cap ($b \le
-30\deg$). To do this, we construct a dust model that incorporates HI column
density maps as tracers of the dust intensity structures and a phenomenological
description of the Galactic magnetic field. By adjusting the parameters of the
dust model, we were able to reproduce the Planck dust observations at 353 GHz
in the selected region. Realistic simulations of the polarized dust emission
enabled by such a dust model are useful for testing the accuracy of component
separation methods, studying non-Gaussianity, and constraining the amount of
decorrelation with frequency.


title:
Lightweight Interactions for Reciprocal Cooperation in a Social Network
  Game

abstract:
  The construction of reciprocal relationships requires cooperative
interactions during the initial meetings. However, cooperative behavior with
strangers is risky because the strangers may be exploiters. In this study, we
show that people increase the likelihood of cooperativeness of strangers by
using lightweight non-risky interactions in risky situations based on the
analysis of a social network game (SNG). They can construct reciprocal
relationships in this manner. The interactions involve low-cost signaling
because they are not generated at any cost to the senders and recipients.
Theoretical studies show that low-cost signals are not guaranteed to be
reliable because the low-cost signals from senders can lie at any time.
However, people used low-cost signals to construct reciprocal relationships in
an SNG, which suggests the existence of mechanisms for generating reliable,
low-cost signals in human evolution.


title: Meaning = Information + Evolution

abstract:
  Notions like meaning, signal, intentionality, are difficult to relate to a
physical word. I study a purely physical definition of "meaningful
information", from which these notions can be derived. It is inspired by a
model recently illustrated by Kolchinsky and Wolpert, and improves on Dretske
classic work on the relation between knowledge and information. I discuss what
makes a physical process into a "signal".


title: Web 2.0 for Small and medium Sized Companies: A practical Case Study

abstract:
  This project is a holistic analysis of web 2.0 and combines ideas from
systems theory and organizational theory and goes on to attempt to bridge the
gap between the ongoing theoretical discourse and its implications for the
development process. The goal is to shift the discussion from a descriptive,
highly philosophical one to a prescriptive framework that can directly be
applied for the design, evaluation and deployment. Effectively this work posits
that unless a practical framework can be synthesized from this rich debate the
application and development of web 2.0 is at risk of proceeding haphazardly and
this could potentially limit the benefits organizations reap from it. It then
establishes the applicability of web 2.0 to the small organization and
accordingly applies the framework to a practical case study.


title: Radial acceleration relation and dissipative dark matter

abstract:
  Observations indicate that ordinary matter, the baryons, influence the
structural properties of dark matter on galactic scales. One such indication is
the radial acceleration relation, which is a tight correlation between the
measured gravitational acceleration and that expected from the baryons. We show
here that the dark matter density profile that has been motivated by
dissipative dark matter models, including mirror dark matter, can reproduce
this radial acceleration relation.


title: The number of relatively $r$-prime $k$-tuple integers

abstract:
  For a fixed integer $r\ge1$, we say $k$-tuple integers $(x_1,\ldots,x_k)$ are
relatively $r$-prime if there exists no prime $p$ such that all $k$ integers is
multiple of $p^r$. Benkoski proved that the number of relatively $r$-prime
$k$-tuple integers in $[1,x]^k$ is $x^k/\zeta(rk)+$(Error term). We showed that
the exact order of error term is $x^{k-1}$ for $rk\ge3$ and $k\not=1$.


title:
Distribution of class numbers in continued fraction families of real
  quadratic fields

abstract:
  We construct a random model to study the distribution of class numbers in
special families of real quadratic fields $\mathbb Q(\sqrt d)$ arising from
continued fractions. These families are obtained by considering periodic
continued fraction expansions of the form $\sqrt {D(n)}=[f(n), [u_1, u_2,
\dots, u_{s-1}, 2f(n)]]$ with fixed coefficients $u_1, \dots, u_{s-1}$ and
generalize well-known families such as Chowla's $4n^2+1$, for which analogous
results were recently proved by Dahl and Lamzouri.


title: Matrix Representation for Multiplicative Nested Sums

abstract:
  We study multiplicative nested sums, which are generalizations of harmonic
sums, and provide a calculation through multiplication of index matrices.
Special cases interpret the index matrices as stochastic transition matrices of
random walks on a finite number of sites. Relations among multiplicative nested
sums, which are generalizations of relations between harmonic series and
multiple zeta functions, can be easily derived from identities of the index
matrices. Combinatorial identities and their generalizations can also be
derived from this computation.


title: Remarkable signals of $t_R$ compositeness

abstract:
  We are looking for remarkable differences between predictions of the standard
model and those of $t_R$ compositeness (while the $t_L$ remains elementary) in
various basic $t\bar t$ production processes, without having to make difficult
final polarization analyses. We assume the presence of $q^2$ dependent form
factors which first suppress the $t_R$ contributions at high $q^2$, and in
addition, may also lead to an effective $q^2$ dependent top mass. We further
assume that these effects disappear at low $q^2$ so that there are no anomalous
couplings. We show that large specific differences indeed appear in the high
energy limits of cross sections and asymmetries in $e^-e^+$, gluon+gluon,
$\gamma\gamma$ collisions and other fusion processes and that this should lead
to a strategy for analyzing them.


title: Quantum sensing

abstract:
  "Quantum sensing" describes the use of a quantum system, quantum properties
or quantum phenomena to perform a measurement of a physical quantity.
Historical examples of quantum sensors include magnetometers based on
superconducting quantum interference devices and atomic vapors, or atomic
clocks. More recently, quantum sensing has become a distinct and rapidly
growing branch of research within the area of quantum science and technology,
with the most common platforms being spin qubits, trapped ions and flux qubits.
The field is expected to provide new opportunities - especially with regard to
high sensitivity and precision - in applied physics and other areas of science.
In this review, we provide an introduction to the basic principles, methods and
concepts of quantum sensing from the viewpoint of the interested
experimentalist.


title:
Measurement of $W^{\pm}W^{\pm}$ vector-boson scattering and limits on
  anomalous quartic gauge couplings with the ATLAS detector

abstract:
  This paper presents the extended results of measurements of
$W^{\pm}W^{\pm}jj$ production and limits on anomalous quartic gauge couplings
using 20.3 ${\rm fb}^{-1}$ of proton-proton collision data at $\sqrt{s}=8$ TeV
recorded by the ATLAS detector at the Large Hadron Collider. Events with two
leptons ($e$ or $\mu$) with the same electric charge and at least two jets are
analyzed. Production cross-sections are determined in two fiducial regions,
with different sensitivities to the electroweak and strong production
mechanisms. An additional fiducial region, particularly sensitive to anomalous
quartic gauge coupling parameters $\alpha_4$ and $\alpha_5$, is introduced,
which allows more stringent limits on these parameters compared to the previous
ATLAS measurement.


title: Complementing Model Learning with Mutation-Based Fuzzing

abstract:
  An ongoing challenge for learning algorithms formulated in the Minimally
Adequate Teacher framework is to efficiently obtain counterexamples. In this
paper we compare and combine conformance testing and mutation-based fuzzing
methods for obtaining counterexamples when learning finite state machine models
for the reactive software systems of the Rigorous Exampination of Reactive
Systems (RERS) challenge. We have found that for the LTL problems of the
challenge the fuzzer provided an independent confirmation that the learning
process had been successful, since no additional counterexamples were found.
For the reachability problems of the challenge, however, the fuzzer discovered
more reachable error states than the learner and tester, albeit in some cases
the learner and tester found some that were not discovered by the fuzzer. This
leads us to believe that these orthogonal approaches are complementary in the
context of model learning.


title: Three-observer Bell inequality violation on a two-qubit entangled state

abstract:
  Bipartite Bell inequalities can be simultaneously violated by two different
pairs of observers when weak measurements and signaling is employed. Here we
experimentally demonstrate the violation of two simultaneous CHSH inequalities
by exploiting a two-photon polarization maximally entangled state. Our results
demonstrate that large double violation is experimentally achievable. Our
demonstration may have impact for Quantum Key Distribution or certification of
Quantum Random Number generators based on weak measurements.


title:
Distributed recovery of jointly sparse signals under communication
  constraints

abstract:
  The problem of the distributed recovery of jointly sparse signals has
attracted much attention recently. Let us assume that the nodes of a network
observe different sparse signals with common support; starting from linear,
compressed measurements, and exploiting network communication, each node aims
at reconstructing the support and the non-zero values of its observed signal.
In the literature, distributed greedy algorithms have been proposed to tackle
this problem, among which the most reliable ones require a large amount of
transmitted data, which barely adapts to realistic network communication
constraints. In this work, we address the problem through a reweighted $\ell_1$
soft thresholding technique, in which the threshold is iteratively tuned based
on the current estimate of the support. The proposed method adapts to
constrained networks, as it requires only local communication among neighbors,
and the transmitted messages are indices from a finite set. We analytically
prove the convergence of the proposed algorithm and we show that it outperforms
the state-of-the-art greedy methods in terms of balance between recovery
accuracy and communication load.


title:
Giant magnetoresistance in electrodeposited Co-Cu/Cu multilayers: origin
  of absence of oscillatory behaviour

abstract:
  A detailed study of the evolution of the magnetoresistance was performed on
electrodeposited Co/Cu multilayers with Cu layer thicknesses ranging from 0.5
nm to 4.5 nm. For thin Cu layers (up to 1.5 nm), anisotropic magnetoresistance
(AMR) was observed whereas multilayers with thicker Cu layers exhibited clear
giant magnetoresistance (GMR) behaviour. The GMR magnitude increased up to
about 3.5 to 4 nm Cu layer thickness and slightly decreased afterwards.
According to magnetic measurements, all samples exhibited ferromagnetic (FM)
behaviour. The relative remanence turned out to be about 0.75 for both AMR and
GMR type multilayers. This clearly indicates the absence of an
antiferromagnetic (AF) coupling between adjacent magnetic layers for Cu layers
even above 1.5 nm where the GMR effect occurs. The AMR behaviour at low spacer
thicknesses indicates the presence of strong FM coupling (due to, e.g.,
pin-holes in the spacer and/or areas of the Cu layer where the layer thickness
is very small). With increasing spacer thickness, the pin-hole density reduces
and/or the layer thickness uniformity improves which both lead to a weakening
of the FM coupling. This improvement in multilayer structure quality results in
a better separation of magnetic layers and the weaker coupling (or complete
absence of interlayer coupling) enables a more random magnetization orientation
of adjacent layers, all this leading to an increase of the GMR. Coercive field
and zero-field resistivity measurements as well as the results of a structural
study reported earlier on the same multilayers provide independent evidence for
the microstructural features established here. The large GMR reported
previously on such Co/Cu multilayers at Cu layer thicknesses around 1 nm can be
attributed to the presence of a fairly large superparamagnetic (SPM) fraction
rather than being due to a strong AF coupling.


title:
Multiply robust dose-response estimation for multivalued causal
  inference problems

abstract:
  This paper develops a multiply robust (MR) dose-response estimator for causal
inference problems involving multivalued treatments. We combine a family of
generalised propensity score (GPS) models and a family of outcome regression
(OR) models to achieve an average potential outcomes estimator that is
consistent if just one of the GPS or OR models in each family is correctly
specified. We provide proofs and simulations that demonstrate multiple
robustness in the context of multivalued causal inference problems.


title:
Convergence parameters of nonnegative block tri-diagonal matrices and
  their application to multi-dimensional QBD processes

abstract:
  First, we consider a nonnegative homogeneous block tri-diagonal matrix and
obtain its convergence parameter, where some results in the field of matrix
analytic method are extended to the case where block matrices have countably
infinite dimension. Second, we apply our results to a multi-dimensional QBD
process and obtain lower bounds for the directional asymptotic decay rates of
the stationary distribution.


title:
Fast and backward stable computation of roots of polynomials, Part II:
  backward error analysis; companion matrix and companion pencil

abstract:
  This work is a continuation of "Fast and backward stable computation of roots
of polynomials" by J.L. Aurentz, T. Mach, R. Vandebril, and D.S. Watkins, SIAM
Journal on Matrix Analysis and Applications, 36(3): 942--973, 2015. In that
paper we introduced a companion QR algorithm that finds the roots of a
polynomial by computing the eigenvalues of the companion matrix in $O(n^{2})$
time using $O(n)$ memory. We proved that the method is backward stable. Here we
introduce, as an alternative, a companion QZ algorithm that solves a
generalized eigenvalue problem for a companion pencil. More importantly, we
provide an improved backward error analysis that takes advantage of the special
structure of the problem. The improvement is also due, in part, to an
improvement in the accuracy (in both theory and practice) of the turnover
operation, which is the key component of our algorithms.
  We prove that for the companion QR algorithm, the backward error on the
polynomial coefficients varies linearly with the norm of the polynomial's
vector of coefficients. Thus the companion QR algorithm has a smaller backward
error than the unstructured QR algorithm (used by MATLAB's \texttt{roots}
command, for example), for which the backward error on the polynomial
coefficients grows quadratically with the norm of the coefficient vector. The
companion QZ algorithm has the same favorable backward error as companion QR,
provided that the polynomial coefficients are properly scaled.


title: Saturation and geometrical scaling

abstract:
  We discuss emergence of geometrical scaling as a consequence of the nonlinear
evolution equations of QCD, which generate a new dynamical scale, known as the
saturation momentum: Qs. In the kinematical region where no other energy scales
exist, particle spectra exhibit geometrical scaling (GS), i.e. they depend on
the ratio pT=Qs, and the energy dependence enters solely through the energy
dependence of the saturation momentum. We confront the hypothesis of GS in
different systems with experimental data.


title:
Unified Functorial Signal Representation II: Category action, Base
  Hierarchy, Geometries as Base structured categories

abstract:
  In this paper we propose and study few applications of the base structured
categories $\mathcal{X} \rtimes_{\mathbf{F}} \mathbf{C}$, $\int_{\mathbf{C}}
\bar{\mathbf{F}}$, $\mathcal{X} \rtimes_{\mathbb{F}} \mathbf{C}$ and
${\int_{\mathbf{C}} \bar{\mathbb{F}}}$. First we show classic transformation
groupoid $X /\!\!/ G$ simply being a base-structured category
${\int_{\mathbf{G}} \bar{{F}}}$. Then using permutation action on a finite set,
we introduce the notion of a hierarchy of base structured categories
$[(\mathcal{X}_{2a} \rtimes_{\mathbf{F_{2a}}} \mathbf{B}_{2a}) \amalg
(\mathcal{X}_{2b} \rtimes_{\mathbf{F_{2b}}} \mathbf{B}_{2b}) \amalg ...]
\rtimes_{\mathbf{F_{1}}} \mathbf{B}_1$ that models local and global structures
as a special case of composite Grothendieck fibration. Further utilizing the
existing notion of transformation double category $(\mathcal{X}_{1}
\rtimes_{\mathbf{F_{1}}} \mathbf{B}_{1}) /\!\!/ \mathbf{2G}$, we demonstrate
that a hierarchy of bases naturally leads one from 2-groups to n-category
theory. Finally we prove that every classic Klein geometry is the Grothendieck
completion ($\mathbf{G} = \mathcal{X} \rtimes_{\mathbb{F}} \mathbf{H}$) of
${\mathbb{F}}: \mathbf{H} \xrightarrow{{F}} \mathbf{Man}^{\infty}
\xrightarrow{U} \mathbf{Set}$. This is generalized to propose a set-theoretic
definition of a groupoid geometry $(\mathcal{G},\mathcal{B})$ (originally
conceived by Ehresmann through transport and later by Leyton using transfer)
with a principal groupoid $\mathcal{G} = \mathcal{X} \rtimes \mathcal{B}$ and
geometry space $\mathcal{X} = \mathcal{G}/\mathcal{B}$; which is essentially
same as $\mathbf{G} = \mathcal{X} \rtimes_{\mathbb{F}} \mathbf{B}$ or precisely
the completion of ${\mathbb{F}}: \mathbf{B} \xrightarrow{{F}}
\mathbf{Man}^{\infty} \xrightarrow{U} \mathbf{Set}$.


title:
On similarity of binary black hole gravitational-wave skymaps: to
  observe or to wait?

abstract:
  Localization estimates for GW150914, the first binary black hole detected by
the LIGO instruments, were shared with partner facilities for electromagnetic
follow-up. While the source was a compact binary coalescence (CBC), it was
first identified by algorithms that search for unmodeled signals, which
produced the skymaps that directed electromagnetic observations. Later on, CBC
specific algorithms produced refined versions, which showed significant
differences. In this paper we show that those differences were not accidental
and that CBC and unmodeled skymaps for binary black holes will frequently be
different; we thus provide a way to determine whether to observe
electromagnetically as promptly as possible (following a gravitational-wave
detection), or to wait until CBC skymaps become available, should they not be
available in low latency. We also show that, unsurprisingly, CBC algorithms can
yield much smaller searched areas.


title:
Proceedings of the First International Workshop on Argumentation in
  Logic Programming and Non-Monotonic Reasoning (Arg-LPNMR 2016)

abstract:
  This volume contains the papers presented at Arg-LPNMR 2016: First
International Workshop on Argumentation in Logic Programming and Nonmonotonic
Reasoning held on July 8-10, 2016 in New York City, NY.


title: A Bayesian optimization approach to find Nash equilibria

abstract:
  Game theory finds nowadays a broad range of applications in engineering and
machine learning. However, in a derivative-free, expensive black-box context,
very few algorithmic solutions are available to find game equilibria. Here, we
propose a novel Gaussian-process based approach for solving games in this
context. We follow a classical Bayesian optimization framework, with sequential
sampling decisions based on acquisition functions. Two strategies are proposed,
based either on the probability of achieving equilibrium or on the Stepwise
Uncertainty Reduction paradigm. Practical and numerical aspects are discussed
in order to enhance the scalability and reduce computation time. Our approach
is evaluated on several synthetic game problems with varying number of players
and decision space dimensions. We show that equilibria can be found reliably
for a fraction of the cost (in terms of black-box evaluations) compared to
classical, derivative-based algorithms. The method is available in the R
package GPGame available on CRAN at https://cran.r-project.org/package=GPGame.


title:
Dynamical formation of a hairy black hole in a cavity from the decay of
  unstable solitons

abstract:
  Recent numerical relativity simulations within the
Einstein--Maxwell--(charged-)Klein-Gordon (EMcKG) system have shown that the
non-linear evolution of a superradiantly unstable Reissner-Nordstr\"om black
hole (BH) enclosed in a cavity, leads to the formation of a BH with scalar
hair. Perturbative evidence for the stability of such hairy BHs has been
independently established, confirming they are the true endpoints of the
superradiant instability. The same EMcKG system admits also charged scalar
soliton-type solutions, which can be either stable or unstable. Using numerical
relativity techniques, we provide evidence that the time evolution of some of
these $\textit{unstable}$ solitons leads, again, to the formation of a hairy
BH. In some other cases, unstable solitons evolve into a (bald)
Reissner-Nordstr\"om BH. These results establish that the system admits two
distinct channels to form hairy BHs at the threshold of superradiance: growing
hair from an unstable (bald) BH, or growing a horizon from an unstable
(horizonless) soliton. Some parallelism with the case of asymptotically flat
boson stars and Kerr BHs with scalar hair is drawn.


title:
Price Doubling and Item Halving: Robust Revenue Guarantees for Item
  Pricing

abstract:
  We study approximation algorithms for revenue maximization based on static
item pricing, where a seller chooses prices for various goods in the market,
and then the buyers purchase utility-maximizing bundles at these given prices.
We formulate two somewhat general techniques for designing good pricing
algorithms for this setting: Price Doubling and Item Halving. Using these
techniques, we unify many of the existing results in the item pricing
literature under a common framework, as well as provide several new item
pricing algorithms for approximating both revenue and social welfare. More
specifically, for a variety of settings with item pricing, we show that it is
possible to deterministically obtain a log-approximation for revenue and a
constant-approximation for social welfare simultaneously: thus one need not
sacrifice revenue if the goal is to still have decent welfare guarantees. %In
addition, we provide a new black-box reduction from revenue to welfare based on
item pricing, which immediately gives us new revenue-approximation algorithms
(e.g., for gross substitutes valuations).
  The main technical contribution of this paper is a $O((\log m + \log
k)^2)$-approximation algorithm for revenue maximization based on the Item
Halving technique, for settings where buyers have XoS valuations, where $m$ is
the number of goods and $k$ is the average supply. Surprisingly, ours is the
first known item pricing algorithm with polylogarithmic approximations for such
general classes of valuations, and partially resolves an important open
question from the algorithmic pricing literature about the existence of item
pricing algorithms with logarithmic factors for general valuations. We also use
the Item Halving framework to form envy-free item pricing mechanisms for the
popular setting of multi-unit markets, providing a log-approximation to revenue
in this case.


title:
Domain Adaptation with L2 constraints for classifying images from
  different endoscope systems

abstract:
  This paper proposes a method for domain adaptation that extends the maximum
margin domain transfer (MMDT) proposed by Hoffman et al., by introducing L2
distance constraints between samples of different domains; thus, our method is
denoted as MMDTL2. Motivated by the differences between the images taken by
narrow band imaging (NBI) endoscopic devices, we utilize different NBI devices
as different domains and estimate the transformations between samples of
different domains, i.e., image samples taken by different NBI endoscope
systems. We first formulate the problem in the primal form, and then derive the
dual form with much lesser computational costs as compared to the naive
approach. From our experimental results using NBI image datasets from two
different NBI endoscopic devices, we find that MMDTL2 is better than MMDT and
also support vector machines without adaptation, especially when NBI image
features are high-dimensional and the per-class training samples are greater
than 20.


title:
Experimental demonstration of a fully inseparable quantum state with
  nonlocalizable entanglement

abstract:
  Localizability of entanglement in fully inseparable states is a key
ingredient of assisted quantum information protocols as well as
measurement-based models of quantum computing. We investigate the existence of
fully inseparable states with nonlocalizable entanglement, that is, with
entanglement which cannot be localized between any pair of subsystems by any
measurement on the remaining part of the system. It is shown, that the
nonlocalizable entanglement occurs already in suitable mixtures of a
three-qubit GHZ state and white noise. Further, we generalize this set of
states to a two-parametric family of fully inseparable three-qubit states with
nonlocalizable entanglement. Finally, we demonstrate experimentally the
existence of nonlocalizable entanglement by preparing and characterizing one
state from the family using correlated single photons and linear optical
circuit.


title:
A new GPU implementation for lattice-Boltzmann simulations on sparse
  geometries

abstract:
  We describe a high-performance implementation of the lattice Boltzmann method
(LBM) for sparse 3D geometries on graphic processors (GPU). The main
contribution of this work is a data layout that allows to minimise the number
of redundant memory transactions during the propagation step of LBM. We show
that by using a uniform mesh of small three-dimensional tiles and a careful
data placement it is possible to utilise more than 70% of maximum theoretical
GPU memory bandwidth for D3Q19 lattice and double precision numbers. The
performance of our implementation is thoroughly examined and compared with
other GPU implementations of LBM. The proposed method performs the best for
sparse geometries with good spatial locality.


title: Jack characters and enumeration of maps

abstract:
  Jack characters provide dual information about Jack symmetric functions. We
give explicit formulas for the top-degree part of these Jack characters in
terms of bicolored oriented maps with an arbitrary face structure.


title:
Action Recognition Based on Joint Trajectory Maps Using Convolutional
  Neural Networks

abstract:
  Recently, Convolutional Neural Networks (ConvNets) have shown promising
performances in many computer vision tasks, especially image-based recognition.
How to effectively use ConvNets for video-based recognition is still an open
problem. In this paper, we propose a compact, effective yet simple method to
encode spatio-temporal information carried in $3D$ skeleton sequences into
multiple $2D$ images, referred to as Joint Trajectory Maps (JTM), and ConvNets
are adopted to exploit the discriminative features for real-time human action
recognition. The proposed method has been evaluated on three public benchmarks,
i.e., MSRC-12 Kinect gesture dataset (MSRC-12), G3D dataset and UTD multimodal
human action dataset (UTD-MHAD) and achieved the state-of-the-art results.


title:
Phase-space structures and stellar populations in the star-forming
  region NGC~ 2264

abstract:
  In this work we analyse the structure of a subspace of the phase space of the
star-forming region NGC~ 2264 using the Spectrum of Kinematic Groupings (SKG).
We show that the SKG can be used to process a collection of star data to find
substructure at different scales. We have found structure associated with the
NGC~ 2264 region and also with the background area. In the NGC~ 2264 region, a
hierarchical analysis shows substructure compatible with that found in previous
specific studies of the area but with an objective, compact methodology that
allows us to homogeneously compare the structure of different clusters and
star-forming regions. Moreover, this structure is compatible with the different
ages of the main NGC~ 2264 star-forming populations. The structure found in the
field can be roughly associated with giant stars far in the background,
dynamically decoupled from NGC~ 2264, which could be related either with the
Outer Arm or Monoceros Ring. The results in this paper confirm the relationship
between structure in the RV phase-space subspace and different kinds of
populations, defined by other variables not necessarily analysed with the SKG,
such as age or distance, showing the importance of detecting phase-space
substructure in order to trace stellar populations in the broadest sense of the
word.


title: Viscoelectric Effects in Nanochannel Electrokinetics

abstract:
  Electrokinetic transport behavior in nanochannels is different to that in
larger sized channels. Specifically, molecular dynamics (MD) simulations in
nanochannels have demonstrated two little understood phenomena which are not
observed in microchannels, being: (i) the decrease of average electroosmotic
mobility at high surface charge density, and (ii) the decrease of channel
conductance at high salt concentrations, as the surface charge is increased.
However, current electric double layer models do not capture these results. In
this study we provide evidence that this inconsistency primarily arises from
the neglect of the viscoelectric effect (being the increase of local viscosity
near charged surfaces due to water molecule orientation) in conventional
continuum models. It is shown that predictions of electroosmotic mobility in a
slit nanochannel, derived from a viscoelectric-modified continuum model, are in
quantitative agreement with previous MD simulation results. Furthermore,
viscoelectric effects are found to dominate over ion steric and dielectric
saturation effects in both electroosmotic and ion transport processes. Finally,
we indicate that mechanisms of the previous MD-observed phenomena can be
well-explained by the viscoelectric theory.


title:
PipeCNN: An OpenCL-Based FPGA Accelerator for Large-Scale Convolution
  Neuron Networks

abstract:
  Convolutional neural networks (CNNs) have been widely employed in many
applications such as image classification, video analysis and speech
recognition. Being compute-intensive, CNN computations are mainly accelerated
by GPUs with high power dissipations. Recently, studies were carried out
exploiting FPGA as CNN accelerator because of its reconfigurability and energy
efficiency advantage over GPU, especially when OpenCL-based high-level
synthesis tools are now available providing fast verification and
implementation flows. Previous OpenCL-based design only focused on creating a
generic framework to identify performance-related hardware parameters, without
utilizing FPGA's special capability of pipelining kernel functions to minimize
memory bandwidth requirement. In this work, we propose an FPGA accelerator with
a new architecture of deeply pipelined OpenCL kernels. Data reuse and task
mapping techniques are also presented to improve design efficiency. The
proposed schemes are verified by implementing two representative large-scale
CNNs, AlexNet and VGG on Altera Stratix-V A7 FPGA. We have achieved a similar
peak performance of 33.9 GOPS with a 34% resource reduction on DSP blocks
compared to previous work. Our design is openly accessible and thus can be
reused to explore new architectures for neural network accelerators.


title:
Dynamics of the variation of shape of the hysteresis of stress-strain
  cyclic compression curves registered at the investigations of the mechanical
  behavior of composite hydrogels

abstract:
  An unusual type of mechanical behavior was registered while studying the
swollen hydrogel compositions "cellulose-polyacrylamide" in the conditions of
multiple cyclic compression tests with the broad variation of the deformation
speed. While increasing the deformation speed the clearly seen inversion of the
positions of compression and decompression parts of the cyclic stress-strain
curves was detected. While carrying out the cyclic compression tests with
relatively low deformation speed (about 100-200 % of the initial sample's
height per minute) the well defined hysteresis of the stress-strain curve can
de seen and in these conditions the decompression part of the curve is situated
inferior the part corresponding to compression. But while increasing the speed
of the deformation the tendency to the progressive approach of the compression
and decompression curves to each other is clearly seen. This effect results in
the full disappearance of the hysteresis at some value of the deformation
speed: the decompression curve coincides with the compression curve. Along with
the further increase of the deformation speed the hysteresis appears again but
the curve corresponding to compression process is situated inferior the curve
corresponding to decompression: the "inversion" of the hysteresis was detected.
The precise character of this process depends upon the stiffness of the
hydrogel under study. Up to date the convincing explanation of this effect can
not been put forward. The authors can only present some hypotheses to explain
this phenomenon.


title: Variability survey of brightest stars in selected OB associations

abstract:
  The stellar evolution theory of massive stars remains uncalibrated with
high-precision photometric observational data mainly due to a small number of
luminous stars that are monitored from space. Automated all-sky surveys have
revealed numerous variable stars but most of the luminous stars are often
overexposed. Targeted campaigns can improve the time base of photometric data
for those objects.
  The aim of this investigation is to study the variability of luminous stars
at different timescales in young open clusters and OB associations.
  We monitored 22 open clusters and associations from 2011 to 2013 using a
0.25-m telescope. Variable stars were detected by comparing the overall
light-curve scatter with measurement uncertainties. Variability was analysed by
the light curve feature extraction tool FATS. Periods of pulsating stars were
determined using the discrete Fourier transform code SigSpec. We then
classified the variable stars based on their pulsation periods and available
spectral information.
  We obtained light curves for more than 20000 sources of which 354 were found
to be variable. Amongst them we find 80 eclipsing binaries, 31 $\alpha$ Cyg, 13
$\beta$ Cep, 62 Be, 16 slowly pulsating B, 7 Cepheid, 1 $\gamma$ Doradus, 3
Wolf-Rayet and 63 late-type variable stars. Up to 55% of these stars are
potential new discoveries as they are not present in the Variable Star Index
(VSX) database. We find the cluster membership fraction for variable stars to
be 13% with an upper limit of 35%.


title: The Data Complexity of Description Logic Ontologies

abstract:
  We analyze the data complexity of ontology-mediated querying where the
ontologies are formulated in a description logic (DL) of the ALC family and
queries are conjunctive queries, positive existential queries, or acyclic
conjunctive queries. Our approach is non-uniform in the sense that we aim to
understand the complexity of each single ontology instead of for all ontologies
formulated in a certain language. While doing so, we quantify over the queries
and are interested, for example, in the question whether all queries can be
evaluated in polynomial time w.r.t. a given ontology. Our results include a
PTime/coNP-dichotomy for ontologies of depth one in the description logic
ALCFI, the same dichotomy for ALC- and ALCI-ontologies of unrestricted depth,
and the non-existence of such a dichotomy for ALCF-ontologies. For the latter
DL, we additionally show that it is undecidable whether a given ontology admits
PTime query evaluation. We also consider the connection between PTime query
evaluation and rewritability into (monadic) Datalog.


title:
Measurement of the total cross section at 8 TeV and the inelastic cross
  section at 13 TeV at the LHC with the ATLAS detector

abstract:
  New measurements from ATLAS at the LHC are presented on the total cross
section at $\sqrt{s}=8$ TeV from elastic scattering using the ALFA sub-detector
and on the inelastic cross section at $\sqrt{s}=13$ TeV using the MBTS
sub-detector.


title: On the maximum dual volume of a canonical Fano polytope

abstract:
  We give an upper bound on the volume vol(P*) of a polytope P* dual to a
d-dimensional lattice polytope P with exactly one interior lattice point, in
each dimension d. This bound, expressed in terms of the Sylvester sequence, is
sharp, and is achieved by the dual to a particular reflexive simplex. Our
result implies a sharp upper bound on the volume of a d-dimensional reflexive
polytope. Translated into toric geometry, this gives a sharp upper bound on the
anti-canonical degree $(-K_X)^d$ of a d-dimensional toric Fano variety X with
at worst canonical singularities.


title:
Cyclic Coordinate Update Algorithms for Fixed-Point Problems: Analysis
  and Applications

abstract:
  Many problems reduce to the fixed-point problem of solving $x=T(x)$. To this
problem, we apply the coordinate-update algorithms, which update only one or a
few components of $x$ at each step. When each update is cheap, these algorithms
are faster than the full fixed-point iteration (which updates all the
components).
  In this paper, we focus on the coordinate-update algorithms based on the
cyclic selection rules, where the ordering of coordinates in each cycle is
arbitrary. These algorithms are fast, but their convergence is unknown in the
fixed-point setting.
  When $T$ is a nonexpansive operator and has a fixed point, we show that the
sequence of coordinate-update iterates converges to a fixed point under proper
step sizes. This result applies to the primal-dual coordinate-update
algorithms, which have applications to optimization problems with nonseparable
nonsmooth objectives, as well as global linear constraints.
  Numerically, we apply coordinate-update algorithms with the cyclic, shuffled
cyclic, and random selection rules to $\ell_1$ robust least squares, a CT image
reconstruction problem, as well as nonnegative matrix factorization. They
converge much faster than the standard fixed-point iteration. Among the three
rules, cyclic and shuffled cyclic rules are overall faster than the random
rule.


title: Corrected Newtonian potentials in the two-body problem with applications

abstract:
  The paper deals with an analytical study of various corrected Newtonian
potentials. We offer a complete description of the corrected potentials, for
the entire range of the parameters involved. These parameters can be fixed for
different models in order to obtain a good concordance with known data. Some of
the potentials are generated by continued fractions, and another one is derived
from the Newtonian potential by adding a logarithmic correction. The zonal
potential, which models the motion of a satellite moving in the equatorial
plane of the Earth, is also considered. The range of the parameters for which
the potentials behave or not similarly to the Newtonian one is pointed out. The
shape of the potentials is displayed for all the significant cases, as well as
the orbit of Raduga-1M 2 satellite in the field generated by the continued
fractional potential U3, and then by the zonal one. For the continued
fractional potential U2 we study the basic problem of the existence and linear
stability of circular orbits. We prove that such orbits exist and are linearly
stable. This qualitative study offers the possibility to choose the adequate
potential, either for modeling the motion of planets or satellites, or to
explain some phenomena at galactic scale.


title:
Directional Anisotropy of Crack Propagation Along $\Sigma$3 Grain
  Boundary in BCC Fe

abstract:
  Crack growth behaviour along the coherent twin boundary (CTB), i.e.,
$\Sigma$3{112} of BCC Fe is investigated using molecular dynamics (MD)
simulations. The growth of an atomistically sharp crack with {112}$<$110$>$
orientation has been examined along the two opposite $<$111$>$ directions of
CTB under mode-I loading at a constant strain rate. Separate MD simulations
were carried out with crack inserted in the left side, right side and middle of
the specimen model system. The results indicate that the crack grows
differently along the two opposite $<$111$>$ directions. In case of a crack
inserted in the left side, the crack grows in ductile manner, while it
propagates in semi-brittle manner in the case of crack inserted in the right
side. The directional dependence of crack growth along the CTB is also
confirmed by the stress-strain behaviour. This anisotropy in crack growth
behaviour has been attributed to the twinning-antitwinning asymmetry of
1/6$<$111$>$ partial dislocations on {112} planes.


title:
Using cognitive agent-based simulation for the evaluation of indoor
  wayfinding systems

abstract:
  This paper presents a novel approach to simulate human wayfinding behaviour
incorporating visual cognition into a software agent for a computer aided
evaluation of wayfinding systems in large infrastructures. The proposed
approach follows the Sense-Plan-Act paradigm comprised of a model for visual
attention, navigation behaviour and pedestrian movement. Stochastic features of
perception are incorporated to enhance generality and diversity of the
developed wayfinding simulation to reflect a variety of behaviours. The
validity of the proposed approach was evaluated based on empirical data
collected through wayfinding experiments with 20 participants in an immersive
virtual reality environment using a life-sized 3D replica of Vienna's new
central railway station. The results show that the developed cognitive
agent-based simulation provides a further contribution to the simulation of
human wayfinding and subsequently a further step to an effective evaluation
tool for the planning of wayfinding and signage.


title: On coalescence time in graphs--When is coalescing as fast as meeting?

abstract:
  Coalescing random walks is a fundamental stochastic process, where a set of
particles perform independent discrete-time random walks on an undirected
graph. Whenever two or more particles meet at a given node, they merge and
continue as a single random walk. The coalescence time is defined as the
expected time until only one particle remains, starting from one particle at
every node. Despite recent progress the coalescence time for graphs such as
binary trees, d-dimensional tori, hypercubes and more generally,
vertex-transitive graphs, remains unresolved. We provide a powerful toolkit
that results in tight bounds for various topologies including the
aforementioned ones. The meeting time is defined as the worst-case expected
time required for two random walks to arrive at the same node at the same time.
As a general result, we establish that for graphs whose meeting time is only
marginally larger than the mixing time (a factor of log^2 n), the coalescence
time of n random walks equals the meeting time up to constant factors. This
upper bound is complemented by the construction of a graph family demonstrating
that this result is the best possible up to constant factors. For
almost-regular graphs, we bound the coalescence time by the hitting time,
resolving the discrete-time variant of a conjecture by Aldous for this class of
graphs. Finally, we prove that for any graph the coalescence time is bounded by
O(n^3) (which is tight for the Barbell graph); surprisingly even such a basic
question about the coalescing time was not answered before this work. By
duality, our results give bounds on the voter model and therefore give bounds
on the consensus time in arbitrary undirected graphs. We also establish a new
bound on the hitting time and cover time of regular graphs, improving and
tightening previous results by Broder and Karlin, as well as those by Aldous
and Fill.


title:
Dissipation of the excess energy of the adsorbate- thermalization via
  electron transfer

abstract:
  A new scenario of thermalization process of the adsorbate attached at solid
surfaces is proposed. The scenario is based on existence of electric dipole
layer in which the electron wavefunctions extend over the positive ions. Thus
the strong local electric field exists which drags electron into the solids and
repels the positive ions. The electrons are tunneling conveying the energy into
the solid interior. The positive ions are retarded in the field, which allows
them to loose excess kinetic energy and to be located smoothly into the
adsorption sites. In this way the excess energy is not dissipated locally
avoiding melting or creation of defects, in accordance with the experiments.
The scenario is supported by the ab intio calculation results including density
function theory of the slabs representing AlN surface and the Schrodinger
equation for time evolution of hydrogen-like atom at the solid surface.


title: Molecular Assembly on Two-Dimensional Materials

abstract:
  Molecular self-assembly is a well-known technique to create highly functional
nanostructures on surfaces. Self-assembly on two-dimensional materials is a
developing field and has already resulted in the discovery of several rich and
interesting phenomena. Here, we review this progress with an emphasis on the
electronic properties of the adsorbates and the substrate in well-defined
systems, as unveiled by scanning tunneling microscopy (STM). We cover three
aspects of the self-assembly. The first one focuses on non-covalent
self-assembly dealing with site-selectivity due to inherent moire pattern
present on 2D materials deposited on substrates. Modification of intermolecular
interactions and molecule-substrate interactions influences the assembly
drastically and 2D materials can also be used as a platform to carry out
covalent and metal-coordinated assembly. The second part deals with the
electronic properties of molecules adsorbed on 2D materials. By virtue of being
inert and possessing low density of states near the Fermi level, 2D materials
decouple molecules electronically from the underlying metal substrate and allow
high-resolution spectroscopy and imaging of molecular orbitals. The moire
pattern on the 2D materials causes site-selective gating and charging of
molecules in some cases. The last section covers the effects of self-assembled
organic molecules on the electronic properties of graphene as revealed by
spectroscopy and electrical transport measurements. Non-covalent
functionalization of 2D materials has already been applied for their
application as catalysts and sensors. With the current surge of activity on
building van der Waals heterostructures from 2D materials, molecular
self-assembly has the potential to add an extra level of flexibility and
functionality for applications ranging from flexible electronics and OLEDs to
novel electronic devices and spintronics.


title:
Single-Tap Precoders and Decoders for Multi-User MIMO FBMC-OQAM under
  Strong Channel Frequency Selectivity

abstract:
  The design of linear precoders or decoders for multiuser (MU) multiple-input
multiple-output (MIMO) filterbank multicarrier (FBMC) modulations in the case
of strong channel frequency selectivity is presented. The users and the base
station (BS) communicate using space division multiple access (SDMA). The low
complexity proposed solution is based on a single tap per-subcarrier
precoding/decoding matrix at the base station (BS) in the downlink/uplink. As
opposed to classical approaches that assume flat channel frequency selectivity
at the subcarrier level, the BS does not make this assumption and takes into
account the distortion caused by channel frequency selectivity. The expression
of the FBMC asymptotic mean squared error (MSE) in the case of strong channel
selectivity derived in earlier works is developed and extended. The linear
precoders and decoders are found by optimizing the MSE formula under two design
criteria, namely zero forcing (ZF) or minimum mean squared error (MMSE).
Finally, simulation results demonstrate the performance of the optimized
design. As long as the number of BS antennas is larger than the number of
users, it is shown that those extra degrees of freedom can be used to
compensate for the channel frequency selectivity.


title:
InAs nanowire superconducting tunnel junctions: spectroscopy,
  thermometry and nanorefrigeration

abstract:
  We demonstrate an original method -- based on controlled oxidation -- to
create high-quality tunnel junctions between superconducting Al reservoirs and
InAs semiconductor nanowires. We show clean tunnel characteristics with a
current suppression by over $4$ orders of magnitude for a junction bias well
below the Al gap $\Delta_0 \approx 200\,\mu {\rm eV}$. The experimental data
are in close agreement with the BCS theoretical expectations of a
superconducting tunnel junction. The studied devices combine small-scale tunnel
contacts working as thermometers as well as larger electrodes that provide a
proof-of-principle active {\em cooling} of the electron distribution in the
nanowire. A peak refrigeration of about $\delta T = 10\,{\rm mK}$ is achieved
at a bath temperature $T_{bath}\approx250-350\,{\rm mK}$ in our prototype
devices. This method opens important perspectives for the investigation of
thermoelectric effects in semiconductor nanostructures and for nanoscale
refrigeration.


title:
Convergence of an implicit-explicit midpoint scheme for computational
  micromagnetics

abstract:
  Based on lowest-order finite elements in space, we consider the numerical
integration of the Landau-Lifschitz-Gilbert equation (LLG). The dynamics of LLG
is driven by the so-called effective field which usually consists of the
exchange field, the external field, and lower-order contributions such as the
stray field. The latter requires the solution of an additional partial
differential equation in full space. Following Bartels and Prohl (2006)
(Convergence of an implicit finite element method for the
Landau-Lifschitz-Gilbert equation. SIAM J. Numer. Anal. 44), we employ the
implicit midpoint rule to treat the exchange field. However, in order to treat
the lower-order terms effectively, we combine the midpoint rule with an
explicit Adams-Bashforth scheme. The resulting integrator is formally of
second-order in time, and we prove unconditional convergence towards a weak
solution of LLG. Numerical experiments underpin the theoretical findings.


title: Serre Dimension of Monoid Algebras

abstract:
  Let $R$ be a commutative Noetherian ring of dimension $d$, $M$ a commutative
cancellative torsion-free monoid of rank $r$ and $P$ a finitely generated
projective $R[M]$-module of rank $t$. $(1)$ Assume $M$ is $\Phi$-simplicial
seminormal. $(i)$ If $M\in \CC(\Phi)$, then {\it Serre dim} $R[M]\leq d$.
$(ii)$ If $r\leq 3$, then {\it Serre dim} $R[int(M)]\leq d$. $(2)$ If $M\subset
\BZ_+^2$ is a normal monoid of rank $2$, then {\it Serre dim} $R[M]\leq d$.
$(3)$ Assume $M$ is $c$-divisible, $d=1$ and $t\geq 3$. Then $P\cong \wedge^t
P\op R[M]^{t-1}$. $(4)$ Assume $R$ is a uni-branched affine algebra over an
algebraically closed field and $d=1$. Then $P\cong \wedge^t P\op R[M]^{t-1}$.


title:
Confining non-analytic exponential potential $V(x)= g^2\exp\,(2|x|)$ and
  its exact Bessel-function solvability

abstract:
  In a previous paper we have shown that Schr\"odinger equation with the
non-analytic attractive exponential potential $V(x)= -g^2\exp (-|x|)$ is
exactly solvable. It has finitely many discrete eigenstates described by the
Bessel function of the first kind $J_{\nu}(z)$ and the eigenvalues are
specified by the positive zeros of $J_{\nu}(g)$ and $J'_{\nu}(g)$ as a function
of the order $\nu$ with fixed $g>0$. Now we show the corresponding results for
the {\em confining\/} non-analytic exponential potential $V(x)= g^2\exp
(2|x|)$. This has infinitely many discrete eigenstates described by the
modified Bessel function of the second kind $K_{i\nu}(z)$. The eigenvalues are
specified by the {\em pure imaginary zeros\/} of $K_{i\nu}(g)$ and
$K'_{i\nu}(g)$ as a function of the order with fixed $g>0$.

categories: math-ph math.CA math.MP nlin.SI quant-ph


title: Efficient generation of ideals in a discrete Hodge algebra

abstract:
  Let $R$ be a commutative Noetherian ring and $D$ be a discrete Hodge algebra
over $R$ of dimension $d>\text{dim}(R)$. Then we show that
  (i) the top Euler class group $E^d(D)$ of $D$ is trivial.
  (ii) if $d>\text{dim}(R)+1$, then $(d-1)$-st Euler class group $E^{d-1}(D)$
of $D$ is trivial.


title:
Unimodular Elements in Projective Modules and an analogue of a result of
  Mandal

abstract:
  Let $R$ be a Noetherian commutative ring of dimension $n$,
$A=R[X_1,\cdots,X_m]$ be a polynomial ring over $R$ and $P$ be a projective
$A[T]$-module of rank $n$. Assume that $P/TP$ and $P_f$ both contain a
unimodular element for some monic polynomial $f(T)\in A[T]$. Then $P$ has a
unimodular element.


title: Zero Lelong number problem

abstract:
  We discuss several related problems on residual Monge-Amp\`ere masses of
plurisubharmonic functions. The note is based on the author's talk at the 27th
Congress of Nordic Mathematicians, March 19, 2016.


title: Existence of unimodular elements in a projective module

abstract:
  Let $R$ be an affine algebra over an algebraically closed field of
characteristic $0$ with dim$(R)=n$. Let $P$ be a projective
$A=R[T_1,\cdots,T_k]$-module of rank $n$ with determinant $L$. Suppose $I$ is
an ideal of $A$ of height $n$ such that there are two surjections
$\alpha:P\to\!\!\!\to I$ and $\phi:L\oplus A^{n-1} \to\!\!\!\to I$. Assume that
either (a) $k=1$ and $n\geq 3$ or (b) $k$ is arbitrary but $n\geq 4$ is even.
Then $P$ has a unimodular element.


title:
Spectrum sharing in energy harvesting cognitive radio networks: A
  cross-layer perspective

abstract:
  In the paper, we present a cross-layer perspective on data transmission in
energy harvesting cognitive radio networks (CRNs). The delay optimal power
allocation is studied while taking into account the randomness of harvested
energy, data generation, channel state and the grid price. To guarantee primary
user (PU)'s transmission, its Signal-Interference-Ratio (SIR) should be no less
than a threshold. Each user, including PU as well as secondary user (SU), has
energy harvesting devices, and the PU can also purchases the grid power. Each
user is rational and selfish to minimize its own the buffer delay. We formulate
a stochastic Stackelberg game in a bilevel manner. After decoupling via
rewriting the objective and constraints, an equivalent tractable reconstruction
is derived. First, we give a distributive algorithm to obtain the Nash
equilibrium (NE) of the lower level SUs' noncooperative stochastic game.
Thereafter, the stochastic Stackelberg game is discussed under the
circumstances that there is no information exchange between PU and SU.
Distributed iterative algorithms are designed. Furthermore, a distributive
online algorithm is proposed. Finally, simulations are carried out to verify
the correctness and demonstrate the effectiveness of proposed algorithms.


title: Uniform convergence to the Q-process

abstract:
  The first aim of the present note is to quantify the speed of convergence of
a conditioned process toward its Q-process under suitable assumptions on the
quasi-stationary distribution of the process. Conversely, we prove that, if a
conditioned process converges uniformly to a conservative Markov process which
is itself ergodic, then it admits a unique quasi-stationary distribution and
converges toward it exponentially fast, uniformly in its initial distribution.
As an application, we provide a conditional ergodic theorem.


title:
Blowup solutions for a nonlinear heat equation involving a critical
  power nonlinear gradient term

abstract:
  We consider the following exponential reaction-diffusion equation involving a
nonlinear gradient term: $$\partial_t U = \Delta U + \alpha|\nabla U|^2 +
e^U,\quad (x, t)\in\mathbb{R}^N\times[0,T), \quad \alpha > -1.$$ We construct
for this equation a solution which blows up in finite time $T > 0$ and
satisfies some prescribed asymptotic behavior. We also show that the
constructed solution and its gradient blow up in finite time $T$ simultaneously
at the origin, and find precisely a description of its final blowup profile. It
happens that the quadratic gradient term is critical in some senses, resulting
in the change of the final blowup profile in comparison with the case $\alpha =
0$. The proof of the construction inspired by the method of Merle and Zaag in
1997, relies on the reduction of the problem to a finite dimensional one, and
uses the index theory to conclude. One of the major difficulties arising in the
proof is that outside the \textit{blowup region}, the spectrum of the
linearized operator around the profile can never be made negative. Truly new
ideas are needed to achieve the control of the outer part of the solution.
Thanks to a geometrical interpretation of the parameters of the finite
dimensional problem in terms of the blowup time and the blowup point, we obtain
the stability of the constructed solution with respect to perturbations of the
initial data.


title: Minimal cubic surfaces over finite fields

abstract:
  Let $X$ be a minimal cubic surface over a finite field $\mathbb{F}_q$. The
image $\Gamma$ of the Galois group $\operatorname{Gal}(\overline{\mathbb{F}}_q
/ \mathbb{F}_q)$ in the group
$\operatorname{Aut}(\operatorname{Pic}(\overline{X}))$ is a cyclic subgroup of
the Weyl group $W(E_6)$. There are $25$ conjugacy classes of cyclic subgroups
in $W(E_6)$, and $5$ of them correspond to minimal cubic surfaces. It is
natural to ask which conjugacy classes come from minimal cubic surfaces over a
given finite field. In this paper we give a partial answer to this question and
present many explicit examples.


title:
Light cone in the two-dimensional transverse-field Ising model in
  time-dependent mean-field theory

abstract:
  We investigate the propagation of a local perturbation in the two-dimensional
transverse-field Ising model with a time-dependent application of mean-field
theory based on the BBGKY hierarchy. We show that the perturbation propagates
through the system with a finite velocity and that there is transition from
Manhattan to Euclidian metric, resulting in a light cone with an almost
circular shape at sufficiently large distances. The propagation velocity of the
perturbation defining the front of the light cone is discussed with respect to
the parameters of the Hamiltonian and compared to exact results for the
transverse-field Ising model in one dimension.


title: Non-Markovian time evolution of an accelerated qubit

abstract:
  We present a new method for evaluating the response of a moving qubit
detector interacting with a scalar field in Minkowski spacetime. We treat the
detector as an open quantum system, but we do not invoke the Markov
approximation. The evolution equations for the qubit density matrix are valid
at all times, for all qubit trajectories and they incorporate non-Markovian
effects. We analyze in detail the case of uniform acceleration, providing a
detailed characterization of all regimes where non-Markovian effects are
significant. We argue that the most stable characterization of acceleration
temperature refers to the late time behavior of the detector, because
interaction with the field vacuum brings the qubit to a thermal state at the
Unruh temperature. In contrast, the early-time transition rate, that is invoked
in most discussions of acceleration temperature, does not exhibit a thermal
behavior when non-Markovian effects are taken into account. Finally, we note
that the non-Markovian evolution derived here also applies to the
mathematically equivalent problem of a static qubit interacting with a thermal
field bath.


title: Geometric function theory: the art of pullback factorization

abstract:
  In this paper, we develop the foundations of the theory of quasiregular
mappings in general metric measure spaces. In particular, nine definitions of
quasiregularity for a discrete open mapping with locally bounded multiplicity
are proved to be quantitatively equivalent when the metric measure spaces have
locally bounded geometry. We also demonstrate that some, though not all, of
these implications remain true under fairly general hypotheses.
  The major new tool appeared in our approach is a powerful factorization,
termed the pullback factorization, of a quasiregular mapping into the
composition of a 1-BLD mapping and a quasiconformal mapping in locally compact
complete metric measure spaces. This factorization also brings fundamental new
point of view of the theory of quasiregular mappings in Euclidean spaces, in
particular, a branched counterpart of quasisymmetric mappings is introduced and
is shown to be locally equivalent with quasiregular mappings, quantitatively.
  As applications of our new techniques, we answer some well-known open
problems in this field and characterize BLD mappings in metric spaces with
locally bounded geometry. In particular, a conjecture of Heinonen--Rickman is
shown to be false and an open problem of Heinonen--Rickman gets solved
affirmatively.


title: The smallest chimera states

abstract:
  We demonstrate that chimera behavior can be observed in small networks
consisting of three identical oscillators, with mutual all-to-all coupling.
Three different types of chimeras, characterized by the coexistence of two
coherent oscillators and one incoherent oscillator (i.e. rotating with another
frequency) have been identified, where the oscillators show periodic (two
types) and chaotic (one type) behaviors. Typical bifurcations at the
transitions from full synchronization to chimera states and between different
types of chimeras have been described. Parameter regions for the chimera states
are obtained in the form of Arnold tongues, issued from a singular parameter
point. Our analysis suggests that chimera states can be observed in small
networks, relevant to various real-world systems.


title: Quantile Graphical Models: Bayesian Approaches

abstract:
  Graphical models are ubiquitous tools to describe the interdependence between
variables measured simultaneously such as large-scale gene or protein
expression data. Gaussian graphical models (GGMs) are well-established tools
for probabilistic exploration of dependence structures using precision matrices
and they are generated under a multivariate normal joint distribution. However,
they suffer from several shortcomings since they are based on Gaussian
distribution assumptions. In this article, we propose a Bayesian quantile based
approach for sparse estimation of graphs. We demonstrate that the resulting
graph estimation is robust to outliers and applicable under general
distributional assumptions. Furthermore, we develop efficient variational Bayes
approximations to scale the methods for large data sets. Our methods are
applied to a novel cancer proteomics data dataset wherein multiple proteomic
antibodies are simultaneously assessed on tumor samples using reverse-phase
protein arrays (RPPA) technology.


title:
Measurement of the attenuation length of argon scintillation light in
  the ArDM LAr TPC

abstract:
  We report on a measurement of the attenuation length for the scintillation
light in the tonne size liquid argon target of the ArDM dark matter experiment.
The data was recorded in the first underground operation of the experiment in
single-phase operational mode. The results were achieved by comparing the light
yield spectra from 39-Ar and 83m-Kr to a description of the ArDM setup with a
model of full light ray tracing. A relatively low value close to 0.5 m was
found for the attenuation length of the liquid argon bulk to its own
scintillation light. We interpret this result as a presence of optically active
impurities in the liquid argon which are not filtered by the installed
purification systems. We also present analyses of the argon gas employed for
the filling and discuss cross sections in the vacuum ultraviolet of various
molecules in respect to purity requirements in the context of large liquid
argon installations.


title:
Quantification of heparin in complex matrices (including urine) using a
  mix-and-read fluorescence assay

abstract:
  Heparin is an important anticoagulant drug, about one billion doses are
produced annually. It is a polydisperse sulfated polysaccharide, and the
inherent heterogeneity makes the analysis of heparin difficult. The global
crisis resulting from adulterated heparin in 2008 has drawn renewed attention
to the challenges that are associated with the quality control and
characterization of this complex biological medicine from natural sources. The
present study addresses the need for simple and user-friendly analytical
methods for the fast and accurate quantification of heparin in complex
matrices. Direct quantification of heparin in the low microgram per mL range
was accomplished using a specific commercially available assay based on the
fluorescent molecular probe Heparin Red, simply by mixing the heparin
containing sample and a reagent solution in a 96-well microplate followed by
fluorescence readout. A screening of typical impurities in raw heparin
(selected other glycosaminoglycans, residual nucleic acids and proteins),
related to the extraction from animal tissues, as well as of components of the
urine matrix (inorganic salts, amino acids, trace proteins) revealed that these
compounds even in large excess have no or very little effect on the accuracy of
heparin determination. Heparin spike detection in urine, a biological
multicomponent matrix, also showed good accuracy. We envision applications of
this mix-and-read assay in the process and quality control in heparin
manufacturing, but also in pharmacokinetic studies as a convenient tool for
measuring of the urinary excretion of heparins.


title: On-chip magnetic cooling of a nanoelectronic device

abstract:
  We demonstrate significant cooling of electrons in a nanostructure below 10
mK by demagnetisation of thin-film copper on a silicon chip. Our approach
overcomes the typical bottleneck of weak electron-phonon scattering by coupling
the electrons directly to a bath of refrigerated nuclei, rather than cooling
via phonons in the host lattice. Consequently, weak electron-phonon scattering
becomes an advantage. It allows the electrons to be cooled for an
experimentally useful period of time to temperatures colder than the dilution
refrigerator platform, the incoming electrical connections, and the host
lattice. There are efforts worldwide to reach sub-millikelvin electron
temperatures in nanostructures to study coherent electronic phenomena and
improve the operation of nanoelectronic devices. On-chip magnetic cooling is a
promising approach to meet this challenge. The method can be used to reach low,
local electron temperatures in other nanostructures, obviating the need to
adapt traditional, large demagnetisation stages. We demonstrate the technique
by applying it to a nanoelectronic primary thermometer that measures its
internal electron temperature. Using an optimised demagnetisation process, we
demonstrate cooling of the on-chip electrons from 9 mK to below 5 mK for over
1000 seconds.


title:
Best Proximity Point Theorems for Asymptotically Relatively Nonexpansive
  Mappings

abstract:
  Let $(A, B)$ be a nonempty bounded closed convex proximal parallel pair in a
nearly uniformly convex Banach space and $T: A\cup B \rightarrow A\cup B$ be a
continuous and asymptotically relatively nonexpansive map. We prove that there
exists $x \in A\cup B$ such that $\|x - Tx\| = \emph{dist}(A, B)$ whenever
$T(A) \subseteq B$, $T(B) \subseteq A$. Also, we establish that if $T(A)
\subseteq A$ and $T(B) \subseteq B$, then there exist $x \in A$ and $y\in B$
such that $Tx = x$, $Ty = y$ and $\|x - y\| = \emph{dist}(A, B)$. We prove the
aforesaid results when the pair $(A, B)$ has the rectangle property and
property $UC$. In case of $A = B$, we obtain, as a particular case of our
results, the basic fixed point theorem for asymptotically nonexpansive maps by
Goebel and Kirk.


title: On co-dimension two defect operators

abstract:
  Conformal symmetry is broken by a flat or spherical defect operator
$\mathcal{D}$. We show that this defect operator, may be identified as a pair
of twist operators which are inserted at the tips of its causal diamond. Any
$k-$point correlation function in a flat or spherical defect CFT is equivalent
to a $(k+2)-$point correlation function. We reproduce one point correlation
functions and also solve two point correlation functions in defect CFTs .
Mutual R\'enyi entropy is computed and agrees with previous result in a certain
limit. We conjecture there may be universal terms in general co-dimension two
defect CFTs.


title:
On a perfect isometry between principal $p$-blocks of finite groups with
  cyclic $p$-hyperfocal subgroups

abstract:
  Let $G$ be a finite group with a Sylow $p$-subgroup $P$. We prove that the
principal $p$-blocks of $G$ and $N_G(P)$ are perfectly isometric under the
assumption $G$ has a cyclic $p$-hyperfocal subgroup.


title: Fixed points of Hammerstein-type equations on general cones

abstract:
  We obtain new results on the existence and multiplicity of fixed points of
Hammerstein equations in very general cones. In order to achieve this, we
combine a new formulation of cones in terms of continuous functionals with
fixed point index theory. Many examples and an application to boundary value
problems are also included.


title: On the Interplay of Link-Flooding Attacks and Traffic Engineering

abstract:
  Link-flooding attacks have the potential to disconnect even entire countries
from the Internet. Moreover, newly proposed indirect link-flooding attacks,
such as 'Crossfire', are extremely hard to expose and, subsequently, mitigate
effectively. Traffic Engineering (TE) is the network's natural way of
mitigating link overload events, balancing the load and restoring connectivity.
This work poses the question: Do we need a new kind of TE to expose an attack
as well? The key idea is that a carefully crafted, attack-aware TE could force
the attacker to follow improbable traffic patterns, revealing his target and
his identity over time. We show that both existing and novel TE modules can
efficiently expose the attack, and study the benefits of each approach. We
implement defense prototypes using simulation mechanisms and evaluate them
extensively on multiple real topologies.


title:
Calculation of three-body nuclear reactions with angular-momentum and
  parity-dependent optical potentials

abstract:
  Angular-momentum or parity-dependent nonlocal optical potentials for
nucleon-${}^{16}\mathrm{O}$ scattering able to fit differential cross section
data over the whole angular regime are developed and applied to the description
of deuteron-${}^{16}\mathrm{O}$ scattering in the framework of three-body
Faddeev-type equations for transition operators. Differential cross sections
and deuteron analyzing powers for elastic scattering and
${}^{16}\mathrm{O}(d,p){}^{17}\mathrm{O}$ transfer reactions are calculated
using a number of local and nonlocal optical potentials and compared with
experimental data. Angular-momentum or parity-dependence of the optical
potential turns out to be quite irrelevant in the considered three-body
reactions while nonlocality is essential for a successful description of the
differential cross section data, especially in transfer reactions.


title:
Nonadiabatic corrections to fast dispersive multiqubit gates involving Z
  control

abstract:
  We review a time-dependent version of the Schrieffer-Wolff transformation
that accounts for real-time control of system parameters, soon to be rendered
possible on a broad basis due to technical progress. The dispersive regime of
$N$ multilevel systems coupled to a cavity via a Jaynes-Cummings interaction is
extended to the most general case. As a concrete example we rigorously apply
the technique to dispersive two-qubit gates in a superconducting architecture,
showing that fidelities based on previous models are off by up to $10^{-2}$,
which is certainly relevant for high-fidelity gates compatible with
fault-tolerant quantum information devices. A closed analytic form for the
error depending on the target evolution closes our work.


title:
A Novel Framework for Modeling and Mitigating Distributed Link Flooding
  Attacks

abstract:
  Distributed link-flooding attacks constitute a new class of attacks with the
potential to segment large areas of the Internet. Their distributed nature
makes detection and mitigation very hard. This work proposes a novel framework
for the analytical modeling and optimal mitigation of such attacks. The
detection is modeled as a problem of relational algebra, representing the
association of potential attackers (bots) to potential targets. The analysis
seeks to optimally dissolve all but the malevolent associations. The framework
is implemented at the level of online Traffic Engineering (TE), which is
naturally triggered on link-flooding events. The key idea is to continuously
re-route traffic in a manner that makes persistent participation to
link-flooding events highly improbable for any benign source. Thus, bots are
forced to adopt a suspicious behavior to remain effective, revealing their
presence. The load-balancing objective of TE is not affected at all. Extensive
simulations on various topologies validate our analytical findings.


title:
A rare event approach to high dimensional Approximate Bayesian
  computation

abstract:
  Approximate Bayesian computation (ABC) methods permit approximate inference
for intractable likelihoods when it is possible to simulate from the model.
However they perform poorly for high dimensional data, and in practice must
usually be used in conjunction with dimension reduction methods, resulting in a
loss of accuracy which is hard to quantify or control. We propose a new ABC
method for high dimensional data based on rare event methods which we refer to
as RE-ABC. This uses a latent variable representation of the model. For a given
parameter value, we estimate the probability of the rare event that the latent
variables correspond to data roughly consistent with the observations. This is
performed using sequential Monte Carlo and slice sampling to systematically
search the space of latent variables. In contrast standard ABC can be viewed as
using a more naive Monte Carlo estimate. We use our rare event probability
estimator as a likelihood estimate within the pseudo-marginal
Metropolis-Hastings algorithm for parameter inference.
  We provide asymptotics showing that RE-ABC has a lower computational cost for
high dimensional data than standard ABC methods. We also illustrate our
approach empirically, on a Gaussian distribution and an application in
infectious disease modelling.


title: Bots, Seeds and People: Web Archives as Infrastructure

abstract:
  The field of web archiving provides a unique mix of human and automated
agents collaborating to achieve the preservation of the web. Centuries old
theories of archival appraisal are being transplanted into the sociotechnical
environment of the World Wide Web with varying degrees of success. The work of
the archivist and bots in contact with the material of the web present a
distinctive and understudied CSCW shaped problem. To investigate this space we
conducted semi-structured interviews with archivists and technologists who were
directly involved in the selection of content from the web for archives. These
semi-structured interviews identified thematic areas that inform the appraisal
process in web archives, some of which are encoded in heuristics and
algorithms. Making the infrastructure of web archives legible to the archivist,
the automated agents and the future researcher is presented as a challenge to
the CSCW and archival community.


title:
Routing Centralization Across Domains via SDN: A Model and Emulation
  Framework for BGP Evolution

abstract:
  In this work, we propose a radical, incrementally-deployable Internet routing
paradigm in which the control plane of multiple networks is centralized. This
follows the Software Defined Networking (SDN) paradigm, although at the
inter-domain level involving multiple Autonomous Systems (AS). Multi-domain SDN
centralization can be realized by outsourcing routing functions to an external
contractor, which provides inter-domain routing services facilitated through a
multi-AS network controller. The proposed model promises to become a vehicle
for evolving BGP and uses the bird's eye view over several networks to benefit
aspects of inter-domain routing, such as convergence properties, policy
conflict resolution, inter-domain troubleshooting, and collaborative security.
In addition to the proposed paradigm, we introduce a publicly available
emulation platform built on top of Mininet and the Quagga routing software, for
experimenting in hybrid BGP-SDN AS-level networks. As a proof of concept we
focus specifically on exploiting multi-domain centralization to improve BGP's
slow convergence. We build and make publicly available a first multi-AS
controller tailored to this use case and demonstrate experimentally that SDN
centralization helps to linearly reduce BGP convergence times and churn rates
with expanding SDN deployments.


title:
Singularity of generalized grey Brownian motions with different
  parameters

abstract:
  In this note we prove that the probability measures generated by two
generalized grey Brownian motions with different parameters are singular with
respect to each other. This result can be interpreted as an extension of the
Feldman-H\'ajek dichotomy of Gaussian measures to a family of non-Gaussian
measures


title: Multidimensional Asymptotic Consensus in Dynamic Networks

abstract:
  We study the problem of asymptotic consensus as it occurs in a wide range of
applications in both man-made and natural systems. In particular, we study
systems with directed communication graphs that may change over time.
  We recently proposed a new family of convex combination algorithms in
dimension one whose weights depend on the received values and not only on the
communication topology. Here, we extend this approach to arbitrarily high
dimensions by introducing two new algorithms: the ExtremePoint and the Centroid
algorithm. Contrary to classical convex combination algorithms, both have
component-wise contraction rates that are constant in the number of agents.
Paired with a speed-up technique for convex combination algorithms, we get a
convergence time linear in the number of agents, which is optimal.
  Besides their respective contraction rates, the two algorithms differ in the
fact that the Centroid algorithm's update rule is independent of any coordinate
system while the ExtremePoint algorithm implicitly assumes a common agreed-upon
coordinate system among agents. The latter assumption may be realistic in some
man-made multi-agent systems but is highly questionable in systems designed for
the modelization of natural phenomena.
  Finally we prove that our new algorithms also achieve asymptotic consensus
under very weak connectivity assumptions, provided that agent interactions are
bidirectional.


title:
Asymmetric 6-vertex model and classical Ruijsenaars-Schneider system of
  particles

abstract:
  We discuss the correspondence between models solved by Bethe ansatz and
classical integrable systems of Calogero type. We illustrate the correspondence
by the simplest example of the inhomogeneous asymmetric 6-vertex model
parametrized by trigonometric (hyperbolic) functions.


title: Generic Construction of Efficient Matrix Product Operators

abstract:
  Matrix Product Operators (MPOs) are at the heart of the second-generation
Density Matrix Renormalisation Group (DMRG) algorithm formulated in Matrix
Product State language. We first summarise the widely known facts on MPO
arithmetic and representations of single-site operators. Second, we introduce
three compression methods (Rescaled SVD, Deparallelisation and Delinearisation)
for MPOs and show that it is possible to construct efficient representations of
arbitrary operators using MPO arithmetic and compression. As examples, we
construct powers of a short-ranged spin-chain Hamiltonian, a complicated
Hamiltonian of a two-dimensional system and, as proof of principle, the
long-range four-body Hamiltonian from quantum chemistry.


title: A variational method for spectral functions

abstract:
  The Generalized Eigenvalue Problem (GEVP) has been used extensively in the
past in order to reliably extract energy levels from time-dependent Euclidean
correlators calculated in Lattice QCD. We propose a formulation of the GEVP in
frequency space. Our approach consists of applying the model-independent
Backus-Gilbert method to a set of Euclidean two-point functions with common
quantum numbers. A GEVP analysis in frequency space is then applied to a matrix
of estimators that allows us, among other things, to obtain particular linear
combinations of the initial set of operators that optimally overlap to
different local regions in frequency. We apply this method to lattice data from
NRQCD. This approach can be interesting both for vacuum physics as well as for
finite-temperature problems.


title: Structure of the optimal path to a fluctuation

abstract:
  Macroscopic fluctuations have become an essential tool to understand physics
far from equilibrium due to the link between their statistics and
nonequilibrium ensembles. The optimal path leading to a fluctuation encodes key
information on this problem, shedding light on e.g. the physics behind the
enhanced probability of rare events out of equilibrium, the possibility of
dynamic phase transitions and new symmetries. This makes the understanding of
the properties of these optimal paths a central issue. Here we derive a
fundamental relation which strongly constraints the architecture of these
optimal paths for general $d$-dimensional nonequilibrium diffusive systems, and
implies a non-trivial structure for the dominant current vector fields.
Interestingly, this general relation (which encompasses and explains previous
results) makes manifest the spatio-temporal non-locality of the current
statistics and the associated optimal trajectories.

categories: cond-mat.stat-mech cond-mat.mes-hall cond-mat.soft math-ph math.MP


title: The Probability of Generating the Symmetric Group

abstract:
  We consider the probability $p(S_n)$ that a pair of random permutations
generates either the alternating group $A_n$ or the symmetric group $S_n$.
Dixon (1969) proved that $p(S_n)$ approaches $1$ as $n\to\infty$ and
conjectured that $p(S_n)=1-1/n+o(1/n)$. This conjecture was verified by Babai
(1989), using the Classification of Finite Simple Groups. We give an elementary
proof of this result; specifically we show that $p(S_n)=1-1/n+\mathcal
{O}(n^{-2+\epsilon})$. Our proof is based on character theory and character
estimates, including recent work by Schlage-Puchta (2012).


title: On the influence of the environment on galactic chemical abundances

abstract:
  We examine the influence of the environment on the chemical abundances of
late-type galaxies with masses of 10^9.1 M_sun - 10^11 M_sun using data from
the Sloan Digital Sky Survey(SDSS). We find that the environmental influence on
galactic chemical abundances is strongest for galaxies with masses of 10^9.1
M_sun to 10^9.6 Msun. The galaxies in the densest environments may exceed the
average oxygen abundances by about 0.05 dex (the median value of the
overabundances for 101 galaxies in the densest environments) and show higher
abundances in nitrogen by about 0.1. The abundance excess decreases with
increasing galaxy mass and with decreasing environmental density. Since only a
small fraction of late-type galaxies is located in high-density environments
these galaxies do not have a significant influence on the general X/H - M
relation. The metallicity - mass relations for isolated galaxies and for
galaxies with neighbors are very similar. The mean shift of non-isolated
galaxies around the metallicity - mass relation traced by the isolated galaxies
is less than 0.01 dex for oxygen and less than 0.02 dex for nitrogen. The
scatter in the galactic chemical abundances is large for any number of neighbor
galaxies (at any environmental density), i.e., galaxies with both enhanced and
reduced abundances can be found at any environmental density. This suggests
that environmental effects do not play a key role in evolution of late-type
galaxies as was also concluded in some of the previous studies.


title:
Fatigue Deformation of Polycrystalline Cu Using Molecular Dynamics
  Simulations

abstract:
  Molecular dynamics (MD) simulations have been performed to investigate the
fatigue deformation behaviour of polycrystalline Cu with grain size of 5.4 nm.
The samples were prepared using Voronoi algorithm with random grain
orientations. Fatigue simulations were carried out by employing fully reversed,
total strain controlled cyclic loading at strain amplitude of $\pm4$\% for 10
cycles. The MD simulation results indicated that the deformation behaviour
under cyclic loading is dominated by the slip of partial dislocations enclosing
the stacking faults. At higher number of cycles, the grain boundary migration
leading to coarsening of larger grains at the expense of the smaller grains has
been observed. The cyclic stress-strain behaviour, the deformation mechanisms
and the variation of dislocation density as a function of cyclic deformation
have been discussed.