title: Was Venus the First Habitable World of our Solar System?

abstract:
  Present-day Venus is an inhospitable place with surface temperatures
approaching 750K and an atmosphere over 90 times as thick as present day
Earth's. Billions of years ago the picture may have been very different. We
have created a suite of 3D climate simulations using topographic data from the
Magellan mission, solar spectral irradiance estimates for 2.9 and 0.715 billion
years ago, present day Venus orbital parameters, an ocean volume consistent
with current theory and measurements, and an atmospheric composition estimated
for early Venus. Using these parameters we find that such a world could have
had moderate temperatures if Venus had a rotation period slower than about 16
Earth days, despite an incident solar flux 46-70% higher than modern Earth
receives. At its current rotation period of 243 days, Venus's climate could
have remained habitable until at least 715 million years ago if it hosted a
shallow primordial ocean. These results demonstrate the vital role that
rotation and topography play in understanding the climatic history of
exoplanetary Venus-like worlds being discovered in the present epoch.


title: Thermal fluctuations of an interface near a contact line

abstract:
  The effect of thermal fluctuations near a contact line of a liquid interface
partially wetting an impenetrable substrate is studied analytically and
numerically. Promoting both the interface profile and the contact line position
to random variables, we explore the equilibrium properties of the corresponding
fluctuating contact line problem based on an interfacial Hamiltonian involving
a "contact" binding potential. To facilitate an analytical treatment we
consider the case of a one-dimensional interface. The effective boundary
condition at the contact line is determined by a dimensionless parameter that
encodes the relative importance of thermal energy and substrate energy at the
microscopic scale. We find that this parameter controls the transition from a
partially wetting to a pseudo-partial wetting state, the latter being
characterized by a thin prewetting film of fixed thickness. In the partial
wetting regime, instead, the profile typically approaches the substrate via an
exponentially thinning prewetting film. We show that, independently of the
physics at the microscopic scale, Young's angle is recovered sufficiently far
from the substrate. The fluctuations of the interface and of the contact line
give rise to an effective disjoining pressure, exponentially decreasing with
height. Fluctuations therefore provide a regularization of the singular contact
forces occurring in the corresponding deterministic problem.


title:
Detection of money laundering groups using supervised learning in
  networks

abstract:
  Money laundering is a major global problem, enabling criminal organisations
to hide their ill-gotten gains and to finance further operations. Prevention of
money laundering is seen as a high priority by many governments, however
detection of money laundering without prior knowledge of predicate crimes
remains a significant challenge. Previous detection systems have tended to
focus on individuals, considering transaction histories and applying anomaly
detection to identify suspicious behaviour. However, money laundering involves
groups of collaborating individuals, and evidence of money laundering may only
be apparent when the collective behaviour of these groups is considered. In
this paper we describe a detection system that is capable of analysing group
behaviour, using a combination of network analysis and supervised learning.
This system is designed for real-world application and operates on networks
consisting of millions of interacting parties. Evaluation of the system using
real-world data indicates that suspicious activity is successfully detected.
Importantly, the system exhibits a low rate of false positives, and is
therefore suitable for use in a live intelligence environment.


title: Jordan constant for Cremona group of rank 3

abstract:
  We give explicit bounds for Jordan constants of groups of birational
automorphisms of rationally connected threefolds over fields of zero
characteristic, in particular, for Cremona groups of ranks 2 and 3.


title:
Strong limit theorems for extended independent and extended negatively
  dependent random variables under non-linear expectations

abstract:
  Limit theorems for non-additive probabilities or non-linear expectations are
challenging issues which have raised progressive interest recently. The purpose
of this paper is to study the strong law of large numbers and the law of the
iterated logarithm for a sequence of random variables in a sub-linear
expectation space under a concept of extended independence which is much weaker
and easier to verify than the independence proposed by Peng (2008b). We
introduce a concept of extended negative dependence which is an extension of
this kind of weak independence and the extended negative independence relative
to classical probability appeared in recent literatures. Powerful tools as the
moment inequality and Kolmogorov's exponential inequality are established for
this kind of extended negatively independent random variables, which improve
those of Chen, Chen and Ng(2010) a lot. And the strong law of large numbers and
the law of iterated logarithm are obtained by applying these inequalities.


title:
Disky elliptical galaxies and the allegedly over-massive black hole in
  the compact massive `ES' galaxy NGC 1271

abstract:
  While spiral and lenticular galaxies have large-scale disks extending beyond
their bulges, and most local early-type galaxies with 10^{10} < M_*/M_Sun <
2x10^{11} contain a disk (e.g., ATLAS^3D), the early-type galaxies do possess a
range of disk sizes. The edge-on, `intermediate-scale' disk in the `disky
elliptical' galaxy NGC 1271 has led to some uncertainty as to what its
spheroidal component is. Walsh et al. reported a directly measured black hole
mass of 3x10^9 M_Sun for this galaxy; which they remarked was an order of
magnitude greater than what they expected based on their derivation of the host
spheroid's luminosity. Our near-infrared image analysis supports a small
embedded disk within a massive spheroidal component with M_{sph,*} =
(0.9+/-0.2)x10^{11} M_Sun (using M_*/L_H = 1.4 from Walsh et al.). This places
NGC 1271 just 1.6-sigma above the near-linear M_bh-M_{sph,*} relation for
early-type galaxies. Therefore, past speculation that there may be a systematic
difference in the black hole scaling relations between compact massive
early-type galaxies with intermediate-scale disks, i.e. ES galaxies such as NGC
1271, and early-type galaxies with either no substantial disk (E) or a
large-scale disk (S0) is not strongly supported by NGC 1271. We additionally
(i) show how ES galaxies fit naturally in the (`bulge'-to-total)-(morphological
type) diagram, while noting a complication with recent revisions to the
Hubble-Jeans tuning-fork diagram, (ii) caution about claims of over-massive
black holes in other ES galaxies if incorrectly modelled as S0 galaxies, and
(iii) reveal that the compact massive spheroid in NGC 1271 has properties
similar to bright bulges in other galaxies which have grown larger-scale disks.


title: Size-Consistent Statistics for Anomaly Detection in Dynamic Networks

abstract:
  An important task in network analysis is the detection of anomalous events in
a network time series. These events could merely be times of interest in the
network timeline or they could be examples of malicious activity or network
malfunction. Hypothesis testing using network statistics to summarize the
behavior of the network provides a robust framework for the anomaly detection
decision process. Unfortunately, choosing network statistics that are dependent
on confounding factors like the total number of nodes or edges can lead to
incorrect conclusions (e.g., false positives and false negatives). In this
dissertation we describe the challenges that face anomaly detection in dynamic
network streams regarding confounding factors. We also provide two solutions to
avoiding error due to confounding factors: the first is a randomization testing
method that controls for confounding factors, and the second is a set of
size-consistent network statistics which avoid confounding due to the most
common factors, edge count and node count.


title: On the Minimum Number of Hamiltonian Cycles in Regular Graphs

abstract:
  A graph construction that produces a k-regular graph on n vertices for any
choice of k >= 3 and n = m(k+1) for integer m >= 2 is described. The number of
Hamiltonian cycles in such graphs can be explicitly determined as a function of
n and k, and empirical evidence is provided that suggests that this function
gives a tight upper bound on the minimum number of Hamiltonian cycles in
k-regular graphs on n vertices for k >= 5 and n >= k + 3. An additional graph
construction for 4-regular graphs is described for which the number of
Hamiltonian cycles is superior to the above function in the case when k = 4 and
n >= 11.


title:
Elastic interactions between topological defects in chiral nematic
  shells

abstract:
  We present a novel, self-consistent and robust theoretical model to
investigate elastic interactions between topological defects in liquid crystal
shells. Accounting for the non-concentric nature of the shell in a simple
manner, we are able to successfully and accurately explain and predict the
positions of the defects, most relevant in the context of colloidal
self-assembly. We calibrate and test our model on existing experimental data,
and extend it to all newly observed defects configurations in chiral nematic
shells. We perform new experiments to check further and confirm the validity of
the present model. Moreover, we are able to obtain quantitative estimates of
the energies of $+1$ or $+3/2$ disclination lines in cholesterics, whose
intricate nature was only reported recently.


title: The colored symmetric and exterior algebras

abstract:
  We study colored generalizations of the symmetric algebra and its Koszul
dual, the exterior algebra. The symmetric group $\mathfrak{S}_n$ acts on the
multilinear components of these algebras. While $\mathfrak{S}_n$ acts trivially
on the multilinear components of the colored symmetric algebra, we use poset
topology techniques to understand the representation on its Koszul dual. We
introduce an $\mathfrak{S}_n$-poset of weighted subsets that we call the
weighted boolean algebra and we prove that the multilinear components of the
colored exterior algebra are $\mathfrak{S}_n$-isomorphic to the top cohomology
modules of its maximal intervals. We use a technique of Sundaram to compute
group representations on Cohen-macaulay posets to give a generating formula for
the Frobenius series of the colored exterior algebra. We exploit that formula
to find an explicit expression for the expansion of the corresponding
representations in terms of irreducible $\mathfrak{S}_n$-representations. We
show that the two colored Koszul dual algebras are Koszul in the sense of
Priddy.


title:
Low-energy electron-irradiation effect on transport properties of
  graphene field effect transistor

abstract:
  We study the effects of low-energy electron beam irradiation up to 10 keV on
graphene based field effect transistors. We fabricate metallic bilayer
electrodes to contact mono- and bi-layer graphene flakes on SiO$_2$, obtaining
specific contact resistivity $\rho_c \simeq 19 k\Omega \mu m^2$ and carrier
mobility as high as 4000 cm$^2$V$^{-1}$s$^{-1}$. By using a highly doped
p-Si/SiO$_2$ substrate as back gate, we analyze the transport properties of the
device and the dependence on the pressure and on the electron bombardment. We
demonstrate that low energy irradiation is detrimental on the transistor
current capability, resulting in an increase of the contact resistance and a
reduction of the carrier mobility even at electron doses as low as 30
$e^-/nm^2$. We also show that the irradiated devices recover by returning to
their pristine state after few repeated electrical measurements.


title:
Critical dynamical properties of a first-order dissipative phase
  transition

abstract:
  We theoretically investigate the critical properties of a single
driven-dissipative nonlinear photon mode. In a well-defined thermodynamical
limit of large excitation numbers, the exact quantum solution describes a
first-order phase transition in the regime where semiclassical theory predicts
optical bistability. We study the behavior of the complex spectral gap
associated with the Liouvillian superoperator of the corresponding master
equation. We show that in this limit the Liouvillian gap vanishes exponentially
and that the bimodality of the photon Wigner function disappears. The
connection between the considered thermodynamical limit of large photon numbers
for the single-mode cavity and the thermodynamical limit of many cavities for a
driven-dissipative Bose-Hubbard system is discussed.


title: Interactive simulations for quantum key distribution

abstract:
  Secure communication protocols are becoming increasingly important, e.g. for
internet-based communication. Quantum key distribution allows two parties,
commonly called Alice and Bob, to generate a secret sequence of 0s and 1s
called a key that is only known to themselves. Classically, Alice and Bob could
never be certain that their communication was not compromised by a malicious
eavesdropper. Quantum mechanics however makes secure communication possible.
The fundamental principle of quantum mechanics that taking a measurement
perturbs the system (unless the measurement is compatible with the quantum
state) also applies to an eavesdropper. Using appropriate protocols to create
the key, Alice and Bob can detect the presence of an eavesdropper by errors in
their measurements. As part of the QuVis Quantum Mechanics Visualization
Project, we have developed a suite of four interactive simulations that
demonstrate the basic principles of three different quantum key distribution
protocols. The simulations use either polarized photons or spin 1/2 particles
as physical realizations. The simulations and accompanying activities are
freely available for use online or download, and run on a wide range of devices
including tablets and PCs. Evaluation with students over three years was used
to refine the simulations and activities. Preliminary studies show that the
refined simulations and activities help students learn the basic principles of
QKD at both the introductory and advanced undergraduate levels.


title:
Effects of disorder on non-unitary $\mathcal{PT}$ symmetric quantum
  walks

abstract:
  $\mathcal{PT}$ symmetry, namely, a combined parity and time-reversal symmetry
can make non-unitary quantum walks exhibit entirely real eigenenergy. However,
it is known that the concept of $\mathcal{PT}$ symmetry can be generalized and
an arbitrary anti-unitary symmetry has a possibility to substitute
$\mathcal{PT}$ symmetry. The aim of the present work is to seek such
non-unitary quantum walks with generalized $\mathcal{PT}$ symmetry by focusing
on effects of spatially random disorder which breaks $\mathcal{PT}$ symmetry.
We numerically find non-unitary quantum walks whose quasi-energy is entirely
real despite $\mathcal{PT}$ symmetry is broken.


title:
Influence of phonon and electron excitations on the free energy of
  defect clusters in solids: A first-principles study

abstract:
  Although many processes of nanostructure evolution in solids occur at
elevated temperatures, basic data obtained from ground state energetics are
used in the modeling of these phenomena. In order to illustrate the effect of
phonon and electron excitations on the free binding energy of defect clusters,
first-principles calculations are performed for vacancy-solute pairs as well as
vacancy and Cu dimers, trimers, and quadromers in bcc Fe. Based on the
equilibrium atomic positions determined by the relaxation of the supercell with
the defect in the ground state under constant volume (CV) as well as zero
pressure (ZP) conditions, the contribution of phonon excitations to the free
binding energy is calculated within the framework of the harmonic
approximation. The contribution of electron excitations is obtained using the
corresponding ground state data for the electronic density of states.
Quasi-harmonic corrections to the ZP-based results do not yield significant
changes in the temperature range relevant for applications. At 1000 K the
maximum decrease/increase of the ZP-based data for the absolute value of the
free binding energy with respect to the corresponding ground state value is
found for the vacancy-W (43%) / vacancy-Mn (35%) pair. These results clearly
demonstrate that contributions of phonon and electron excitation to the free
binding energy of the defect clusters are generally not negligible. The general
behavior of the free binding energy of vacancy and Cu dimers, trimers and
quadromers is similar to that of the vacancy-solute pairs. The results obtained
in this work are of general importance for studies on the thermodynamics and
kinetics of defect clusters in solids.


title: Quantum metrology including state preparation and readout times

abstract:
  There is growing belief that the next decade will see the emergence of
sensing devices based on the laws of quantum physics that outperform some of
our current sensing devices. For example, in frequency estimation, using a
probe prepared in an entangled state can, in principle, lead to a precision
gain compared to a probe prepared in a separable state. Even in the presence of
some forms of decoherence, it has been shown that the precision gain can
increase with the number of probe particles $N$. Usually, however, the
entangled and separable state preparation and readout times are assumed to be
negligible. We find that a probe in a maximally entangled (GHZ) state can give
an advantage over a separable state only if the entangled state preparation and
readout times are lower than a certain threshold. When the probe system suffers
dephasing, this threshold is much lower (and more difficult to attain) than it
is for an isolated probe. Further, we find that in realistic situations the
maximally entangled probe gives a precision advantage only up to some finite
number of probe particles $N_\text{cutoff}$ that is lower for a dephasing probe
than it is for an isolated probe.


title: Transmit Optimization for Symbol-Level Spoofing

abstract:
  With recent developments of wireless communication technologies, malicious
users can use them to commit crimes or launch terror attacks, thus imposing new
threats on the public security. To quickly respond to defend these attacks,
authorized parities (e.g., the National Security Agency of the USA) need to
intervene in the malicious communication links over the air. This paper
investigates this emerging wireless communication intervention problem at the
physical layer. Unlike prior studies using jamming to disrupt or disable the
targeted wireless communications, we propose a new physical-layer spoofing
approach to change their communicated information. Consider a fundamental
three-node system over additive white Gaussian noise (AWGN) channels, in which
an intermediary legitimate spoofer aims to spoof a malicious communication link
from Alice to Bob, such that the received message at Bob is changed from
Alice's originally sent message to the one desired by the spoofer. We propose a
new symbol-level spoofing scheme, where the spoofer designs the spoofing signal
via exploiting the symbol-level relationship between each original
constellation point of Alice and the desirable one of the spoofer. In
particular, the spoofer aims to minimize the average spoofing-symbol-error-rate
(SSER), which is defined as the average probability that the symbols decoded by
Bob fail to be changed or spoofed, by designing its spoofing signals over
symbols subject to the average transmit power constraint. By considering two
cases when Alice employs the widely-used binary phase-shift keying (BPSK) and
quadrature phase-shift keying (QPSK) modulations, we obtain the respective
optimal solutions to the two average SSER minimization problems. Numerical
results show that the symbol-level spoofing scheme with optimized transmission
achieves a much lower average SSER, as compared to other benchmark schemes.


title: On a representation of partially-distinguishable populations

abstract:
  A representation of heterogeneous stochastic populations that are composed of
sub-populations with different levels of distinguishability is introduced
together with an analysis of its properties. It is demonstrated that any
instance of this representation where individuals are independent can be
related to a point process on the set of probability measures on the individual
state space. The introduction of the proposed representation is fully
constructive which ensures the meaningfulness of the approach.


title:
On the Power of Simple Reductions for the Maximum Independent Set
  Problem

abstract:
  Reductions---rules that reduce input size while maintaining the ability to
compute an optimal solution---are critical for developing efficient maximum
independent set algorithms in both theory and practice. While several simple
reductions have previously been shown to make small domain-specific instances
tractable in practice, it was only recently shown that advanced reductions (in
a measure-and-conquer approach) can be used to solve real-world networks on
millions of vertices [Akiba and Iwata, TCS 2016]. In this paper we compare
these state-of-the-art reductions against a small suite of simple reductions,
and come to two conclusions: just two simple reductions---vertex folding and
isolated vertex removal---are sufficient for many real-world instances, and
further, the power of the advanced rules comes largely from their initial
application (i.e., kernelization), and not their repeated application during
branch-and-bound. As a part of our comparison, we give the first experimental
evaluation of a reduction based on maximum critical independent sets, and show
it is highly effective in practice for medium-sized networks.


title:
On the Electron Agyrotropy during Rapid Asymmetric Magnetic Island
  Coalescence in Presence of a Guide Field

abstract:
  We present an analysis of the properties of the electron velocity
distribution during island coalescence in asymmetric reconnection with and
without guide field. In a previous study, three main domains were identified,
in the case without guide field, as X-, D- and M-regions featuring different
reconnection evolutions {Cazzola et al. 2015). These regions are also
identified here in the case with guide field. We study the departure from
isotropic and gyrotropic behavior by means of different robust detection
algorithms proposed in the literature. While in the case without guide field
these metrics show an overall agreement, when the guide field is present a
discrepancy in the agyrotropy within some relevant regions is observed, such as
at the separatrices and inside magnetic islands. Moreover, in light of the new
observations from the Multiscale MagnetoSpheric mission, an analysis of the
electron velocity phase-space in these domains is presented.


title: Infinite Unlimited Churn

abstract:
  We study unlimited infinite churn in peer-to-peer overlay networks. Under
this churn, arbitrary many peers may concurrently request to join or leave the
overlay network; moreover these requests may never stop coming. We prove that
unlimited adversarial churn, where processes may just exit the overlay network,
is unsolvable. We focus on cooperative churn where exiting processes
participate in the churn handling algorithm. We define the problem of unlimited
infinite churn in this setting. We distinguish the fair version of the problem,
where each request is eventually satisfied, from the unfair version that just
guarantees progress. We focus on local solutions to the problem, and prove that
a local solution to the Fair Infinite Unlimited Churn is impossible. We then
present and prove correct an algorithm UIUC that solves the Unfair Infinite
Unlimited Churn Problem for a linearized peer-to-peer overlay network. We
extend this solution to skip lists and skip graphs.


title: Elasticae and inradius

abstract:
  The elastic energy of a planar convex body is defined by $E(\Om)=\frac
12\,\int\_{\partial\Om} k^2(s)\,ds$where $k(s)$ is the curvature of the
boundary. In this paper we are interested in the minimization problemof
$E(\Om)$ with a constraint on the inradius of $\Om$. By contrast with all the
other minimization problemsinvolving this elastic energy (with a perimeter,
area, diameter or circumradius constraints) for which thesolution is always the
disk, we prove here that the solution of this minimization problem is not the
disk and we completely characterizeit in terms of elementary functions.


title: Quasi-interpolation on a sparse grid with Gaussian

abstract:
  Motivated by the recent multilevel sparse kernel-based interpolation (MuSIK)
algorithm proposed in [Georgoulis, Levesley and Subhan, SIAM J. Sci. Comput.,
35(2), pp. A815-A831, 2013], we introduce the new quasi-multilevel sparse
interpolation with kernels (Q-MuSIK) via the combination technique. The Q-MuSIK
scheme achieves better convergence and run time in comparison with classical
quasi-interpolation; namely, the Q-MuSIK algorithm is generally superior to the
MuSIK methods in terms of run time in particular in high-dimensional
interpolation problems, since there is no need to solve large algebraic
systems.
  We subsequently propose a fast, low complexity, high-dimensional quadrature
formula based on Q-MuSIK interpolation of the integrand. We present the results
of numerical experimentation for both interpolation and quadrature in high
dimension.


title:
Probing density waves in fluidized granular media with diffusing-wave
  spectroscopy

abstract:
  Density waves are characteristic for fluidized beds and affect measurements
on liquid-like dynamics in fluidized granular media. Here, the intensity
autocorrelation function as obtainable with diffusing-wave spectroscopy is
derived in the presence of density waves. The predictions by the derived form
of the IACF match experimental observations from a gas-fluidized bed. The model
suggests separability of the contribution from density waves from the
contribution by microscopic scatterer displacement to the decay of correlation,
thus paves the way for characterizing microscopic particle motions using
diffusing-wave spectroscopy as well as heterogeneities in fluidized granular
media.


title:
Combining Answer Set Programming and Domain Heuristics for Solving Hard
  Industrial Problems (Application Paper)

abstract:
  Answer Set Programming (ASP) is a popular logic programming paradigm that has
been applied for solving a variety of complex problems. Among the most
challenging real-world applications of ASP are two industrial problems defined
by Siemens: the Partner Units Problem (PUP) and the Combined Configuration
Problem (CCP). The hardest instances of PUP and CCP are out of reach for
state-of-the-art ASP solvers. Experiments show that the performance of ASP
solvers could be significantly improved by embedding domain-specific
heuristics, but a proper effective integration of such criteria in
off-the-shelf ASP implementations is not obvious. In this paper the combination
of ASP and domain-specific heuristics is studied with the goal of effectively
solving real-world problem instances of PUP and CCP. As a byproduct of this
activity, the ASP solver WASP was extended with an interface that eases
embedding new external heuristics in the solver. The evaluation shows that our
domain-heuristic-driven ASP solver finds solutions for all the real-world
instances of PUP and CCP ever provided by Siemens. This paper is under
consideration for acceptance in TPLP.


title: Anytime answer set optimization via unsatisfiable core shrinking

abstract:
  Unsatisfiable core analysis can boost the computation of optimum stable
models for logic programs with weak constraints. However, current solvers
employing unsatisfiable core analysis either run to completion, or provide no
suboptimal stable models but the one resulting from the preliminary disjoint
cores analysis. This drawback is circumvented here by introducing a progression
based shrinking of the analyzed unsatisfiable cores. In fact, suboptimal stable
models are possibly found while shrinking unsatisfiable cores, hence resulting
into an anytime algorithm. Moreover, as confirmed empirically, unsatisfiable
core analysis also benefits from the shrinking process in terms of solved
instances. This paper is under consideration for acceptance in TPLP.


title: All uncountable regular cardinals can be inaccessible in HOD

abstract:
  Assuming the existence of a supercompact cardinal and an inaccessible above
it, we construct a model of ZFC, in which all uncountable regular cardinals are
inaccessible in HOD.


title:
Clustering dynamics in a class of normalised generalised gamma dependent
  priors

abstract:
  Normalised generalised gamma processes are random probability measures that
induce nonparametric prior distributions widely used in Bayesian statistics,
particularly for mixture modelling. We construct a class of dependent
normalised generalised gamma priors induced by a stationary population model of
Moran type, which exploits a generalised P\'olya urn scheme associated with the
prior. We study the asymptotic scaling for the dynamics of the number of
clusters in the sample, which in turn provides a dynamic measure of diversity
in the underlying population. The limit is formalised to be a positive
nonstationary diffusion process which falls outside well known families, with
unbounded drift and an entrance boundary at the origin. We also introduce a new
class of stationary positive diffusions, whose invariant measures are explicit
and have power law tails, which approximate weakly the scaling limit.


title: Coupled spatial multi-mode solitons in microcavity wires

abstract:
  A modal expansion approach is developed and employed to investigate and
elucidate the nonlinear mechanism behind the multistability and formation of
coupled multi-mode polariton solitons in microcavity wires. With pump switched
on and realistic dissipation parameters, truncating the expansion up to the
second-order wire mode, our model predicts two distinct coupled soliton
branches: stable and ustable. Modulational stability of the homogeneous
solution and soliton branches stability are studied. Our simplified 1D model is
in remarkably good agreement with the full 2D mean-field Gross-Pitaevskii
model, reproducing correctly the soliton existence domain upon variation of
pump amplitude and the onset of multistability.


title: Nonadiabatic population transfer in a tangent-pulse driven quantum model

abstract:
  Fine control of the dynamics of a quantum system is the key element to
perform quantum information processing and coherent manipulations for atomic
and molecular systems. In this paper we propose a control protocol using a
tangent-pulse driven model and demonstrate that it indicates a desirable
design, i.e., of being both fast and accurate for population transfer. As
opposed to other existing strategies, a remarkable character of the present
scheme is that high velocity of the nonadiabatic evolution itself not only will
not lead to unwanted transitions but also can suppress the error caused by the
truncation of the driving pulse.


title:
Temperature dependence of exchange biased multiferroic $
  \mathbf{BiFeO_3} $/$ \mathbf{Ni_{81}Fe_{19}} $ polycrystalline bilayer

abstract:
  The temperature dependence of exchange bias properties are studied in
polycrystalline $ \mathrm{BiFeO_3} / \mathrm{Ni_{81}Fe_{19}} $ bilayers, for
different $ \mathrm{BiFeO_3} $ thicknesses. Using a field cooling protocol, a
non-monotonic behavior of the exchange bias field is shown in the
exchange-biased bilayers. Another thermal protocol, the Soeya protocol, related
to the $ \mathrm{BiFeO_3} $ thermal activation energies was carried out and
reveals a two-step evolution of the exchange bias field. The results of these
two different protocols are similar to the ones obtained for measurements
previously reported on epitaxial $ \mathrm{BiFeO_3} $, indicating a driving
mechanism independent of the long-range crystalline arrangement (i.e.,
epitaxial or polycrystalline). An intrinsic property of $ \mathrm{BiFeO_3} $ is
proposed as being the driving mechanism for the thermal dependent magnetization
reversal: the canting of the $ \mathrm{BiFeO_3} $ spins leading to a
biquadratic contribution to the exchange coupling. The temperature dependence
of the magnetization reversal angular behavior agrees with the presence of such
a biquadratic contribution for exchange biased bilayers studied here.


title:
Context Discovery for Model Learning in Partially Observable
  Environments

abstract:
  The ability to learn a model is essential for the success of autonomous
agents. Unfortunately, learning a model is difficult in partially observable
environments, where latent environmental factors influence what the agent
observes. In the absence of a supervisory training signal, autonomous agents
therefore require a mechanism to autonomously discover these environmental
factors, or sensorimotor contexts.
  This paper presents a method to discover sensorimotor contexts in partially
observable environments, by constructing a hierarchical transition model. The
method is evaluated in a simulation experiment, in which a robot learns that
different rooms are characterized by different objects that are found in them.


title: Calculating correlation coefficient for Gaussian copula

abstract:
  When Gaussian copula with linear correlation coefficient is used to model
correlated random variables, one crucial issue is to determine a suitable
correlation coefficient $\rho_z$ in normal space for two variables with
correlation coefficient $\rho_x$. This paper attempts to address this problem.
For two continuous variables, the marginal transformation is approximated by a
weighted sum of Hermite polynomials, then, with Mehler's formula, a polynomial
of $\rho_z$ is derived to approximate the function relationship between
$\rho_x$ and $\rho_z$. If a discrete variable is involved, the marginal
transformation is decomposed into piecewise continuous ones, and $\rho_x$ is
expressed as a polynomial of $\rho_z$ by Taylor expansion. For a given
$\rho_x$, $\rho_z$ can be efficiently determined by solving a polynomial
equation.


title: Charge Fluctuations of an Uncharged Black Hole

abstract:
  In this paper we calculate charge fluctuations of a Schwarzschild black-hole
of mass $M$ confined within a perfectly reflecting cavity of radius R in
thermal equilibrium with various species of radiation and fermions . Charge
conservation is constrained by a Lagrange multiplier (the chemical potential).
Black hole charge fluctuations are expected owing to continuous absorption and
emission of particles by the black hole. For black holes much more massive than
$10^{16} g$ , these fluctuations are exponentially suppressed. For black holes
lighter than this, the Schwarzschild black hole is unstable under charge
fluctuations for almost every possible size of the confining vessel. The
stability regime and the fluctuations are calculated through the second
derivative of the entropy with respect to the charge. The expression obtained
contains many puzzling terms besides the expected thermodynamical fluctuations:
terms corresponding to instabilities that do not depend on the specific value
of charge of the charge carriers and one of them depends on Newton's constant
instead. One of the contributions to the charge fluctuations $\hbar/4\pi$ does
not depend neither on number of species, nor on the the specific charge or even
the size of the confining vessel. As a matter of fact, this term emerges from
the second derivative of the black hole entropy alone, which means that it
corresponds to a genuine quantum mechanical property of the black hole itself.
Such a contribution would cause the event horizon to recede from $2M$ to
$2M-T_{BH}$ or equivalently, by $(4\pi)^{-1}$ of the black hole' s Compton wave
length. Similarly, a Cauchy horizon emerges at the same distance the event
horizon receded.


title:
The meta-abelian elliptic KZB associator and periods of Eisenstein
  series

abstract:
  We compute the image of Enriquez' elliptic KZB associator in the (maximal)
meta-abelian quotient of the fundamental Lie algebra of a once-punctured
elliptic curve. Our main result is an explicit formula for this image in terms
of Eichler integrals of Eisenstein series, and is analogous to Deligne's
computation of the depth one quotient of the Drinfeld associator. We also show
how to retrieve Zagier's extended period polynomials of Eisenstein series, as
well as the values at zero of Beilinson--Levin's elliptic polylogarithms from
the meta-abelian elliptic KZB associator.


title: Identities between dimer partition functions on different surfaces

abstract:
  Given a weighted graph $G$ embedded in a non-orientable surface $\Sigma$, one
can consider the corresponding weighted graph $\widetilde{G}$ embedded in the
so-called orientation cover $\widetilde\Sigma$ of $\Sigma$. We prove identities
relating twisted partition functions of the dimer model on these two graphs.
When $\Sigma$ is the M\"obius strip or the Klein bottle, then
$\widetilde\Sigma$ is the cylinder or the torus, respectively, and under some
natural assumptions, these identities imply relations between the genuine dimer
partition functions $Z(G)$ and $Z(\widetilde{G})$. For example, we show that if
$G$ is a locally but not globally bipartite graph embedded in the M\"obius
strip, then $Z(\widetilde{G})$ is equal to the square of $Z(G)$. This extends
results for the square lattice previously obtained by various authors.


title: Chaotic and regular instantons in helical shell models of turbulence

abstract:
  Shell models of turbulence have a finite-time blowup in the inviscid limit,
i.e., the enstrophy diverges while the single-shell velocities stay finite. The
signature of this blowup is represented by self-similar instantonic structures
traveling coherently through the inertial range. These solutions might
influence the energy transfer and the anomalous scaling properties empirically
observed for the forced and viscous models. In this paper we present a study of
the instantonic solutions for a set of four shell models of turbulence based on
the exact decomposition of the Navier-Stokes equations in helical eigenstates.
We find that depending on the helical structure of each model, instantons are
chaotic or regular. Some instantonic solutions tend to recover mirror symmetry
for scales small enough. Models that have anomalous scaling develop regular non
chaotic instantons. Conversely, models that have non anomalous scaling in the
stationary regime are those that have chaotic instantons. The direction of the
energy carried by each single instanton tends to coincide with the direction of
the energy cascade in the stationary regime. Finally, we find that whenever the
small-scale stationary statistics is intermittent, the instanton is less steep
than the dimensional Kolmogorov scaling, independently of whether or not it is
chaotic. Our findings further support the idea that instantons might be crucial
to describe some aspects of the multi-scale anomalous statistics of shell
models.


title:
Wiretap Channels with Random States Non-Causally Available at the
  Encoder

abstract:
  We study the state-dependent (SD) wiretap channel (WTC) with non-causal
channel state information (CSI) at the encoder. This model subsumes all other
instances of CSI availability as special cases, and calls for an efficient
utilization of the state sequence for both reliability and security purposes. A
lower bound on the secrecy-capacity, that improves upon the previously best
known result published by Prabhakaran et al., is derived based on a novel
superposition coding scheme. Our achievability gives rise to the exact
secrecy-capacity characterization of a class of SD-WTCs that decompose into a
product of two WTCs, where one is independent of the state and the other one
depends only on the state. The results are derived under the strict
semantic-security metric that requires negligible information leakage for all
message distributions.


title: Comment on "K. Hansen, Int. J. Mass Spectrom. 399-400 (2016)51"

abstract:
  The comment by K. Hansen suggests that the time-of-flight mass spectrometry
data in one table in our paper from 2103 in IJMS should be due to a proton
contamination and correspond to protons p instead of deuterons D. The evidence
for such a suggestion is a re-plotting of our data, giving a bond distance of
5.0 pm instead of 2.3 pm, corresponding to state s = 3 instead of s = 2 in the
ultra-dense hydrogen. However, protium has indeed been studied on the next
pages in our paper, giving shorter time-of-flights as expected. A replotting of
our protium results as suggested by Hansen gives a best fit mass of 0.6 u,
showing that the suggested procedure gives consistently too small mass. Hansen
also rejects the rotational energy transfer model as due to our use of D in the
analysis of the data. However, this model has been applied successfully in two
previous publications, including experiments using protium. Hansen also
suggests that the protium is due to a contamination of the source; however, the
gas feed (H2 or D2) and its result is well controlled and monitored. The most
likely source of protons was instead laser-induced nuclear fusion, but the
laser intensity in these experiments was a factor three too low to give strong
fusion. Thus, the suggestion by Hansen is not valid.


title:
Affordable echelle spectroscopy of the eccentric HAT-P-2, WASP-14 and
  XO-3 planetary systems with a sub-meter-class telescope

abstract:
  A new off-shelf low-cost echelle spectrograph was installed recently on the
0.6m telescope at the Star\'a Lesn\'a Observatory (Slovakia). In this paper we
describe in details the radial velocity (RV) analysis of the first three
transiting planetary systems, HAT-P-2, WASP-14 and XO-3, observed with this
instrument. Furthermore, we compare our data with the RV data achieved with
echelle spectrographs of other sub-meter-, meter- and two-meter-class
telescopes in terms of their precision. Finally, we investigate the
applicability of our RV data for modeling orbital parameters.


title:
Contamination from a nearby star cannot explain the anomalous
  transmission spectrum of the ultra-short period giant planet WASP-103b

abstract:
  The planet in the WASP-103 system is an excellent candidate for transmission
spectroscopy because of its large radius and high temperature. Application of
this technique found a variation of radius with wavelength which was far too
strong to be explained by scattering processes in the planetary atmosphere. A
faint nearby star was subsequently detected, whose contamination of the transit
light curves might explain this anomaly. We present a reanalysis of published
data in order to characterise the faint star and assess its effect on the
measured transmission spectrum. The faint star has a mass of 0.72 +/- 0.08 Msun
and is almost certainly gravitationally bound to the planetary system. We find
that its effect on the measured physical properties of the planet and host star
is small, amounting to a planetary radius larger by 0.6 sigma and planetary
density smaller by 0.8 sigma. Its influence on the measured transmission
spectrum is much greater: the spectrum now has a minimum around 760 nm and
opacity rises to both bluer and redder wavelengths. It is a poor match to
theoretical spectra and the spectral slope remains too strong for Rayleigh
scattering. The existence of the faint nearby star cannot therefore explain the
measured spectral properties of this hot and inflated planet. We advocate
further observations of the system, both with high spatial resolution in order
to improve the measured properties of the faint star, and with higher spectral
resolution to confirm the anomalous transmission spectrum of the planet.


title: Some Bounds on the Zero Forcing Number of a Graph

abstract:
  A set $Z$ of vertices of a graph $G$ is a zero forcing set of $G$ if
initially labeling all vertices in $Z$ with $1$ and all remaining vertices of
$G$ with $0$, and then, iteratively and as long as possible, changing the label
of some vertex $u$ from $0$ to $1$ if $u$ is the only neighbor with label $0$
of some vertex with label $1$, results in the entire vertex set of $G$. The
zero forcing number $Z(G)$, defined as the minimum order of a zero forcing set
of $G$, was proposed as an upper bound of the corank of matrices associated
with $G$, and was also considered in connection with quantum physics and logic
circuits. In view of the computational hardness of the zero forcing number,
upper and lower bounds are of interest.
  Refining results of Amos, Caro, Davila, and Pepper, we show that $Z(G)\leq
\frac{\Delta-2}{\Delta-1}n$ for a connected graph $G$ of order $n$ and maximum
degree $\Delta$ at least $3$ if and only if $G$ does not belong to $\{
K_{\Delta+1},K_{\Delta,\Delta},K_{\Delta-1,\Delta},G_1,G_2\}$, where $G_1$ and
$G_2$ are two specific graphs of orders $5$ and $7$, respectively. For a
connected graph $G$ of order $n$, maximum degree $3$, and girth at least $5$,
we show $Z(G)\leq \frac{n}{2}-\Omega\left(\frac{n}{\log n}\right)$. Using a
probabilistic argument, we show $Z(G)\leq
\left(1-\frac{H_r}{r}+o\left(\frac{H_r}{r}\right)\right)n$ for an $r$-regular
graph $G$ of order $n$ and girth at least $5$, where $H_r$ is the $r$-th
harmonic number. Finally, we show $Z(G)\geq (g-2)(\delta-2)+2$ for a graph $G$
of girth $g\in \{ 5,6\}$ and minimum degree $\delta$, which partially confirms
a conjecture of Davila and Kenter.


title:
Recovering an electromagnetic obstacle by a few phaseless backscattering
  measurements

abstract:
  We consider the electromagnetic scattering from a convex polyhedral PEC or
PMC obstacle due to a time-harmonic incident plane wave. It is shown that the
modulus of the far-field pattern in the backscattering aperture possesses a
certain local maximum behavior. Using the local maximum indicating phenomena,
one can determine the exterior unit normal directions, as well as the face
areas, of the front faces of the obstacle. Then we propose a recovery scheme of
reconstructing the obstacle by phaseless backscattering measurements. This work
significantly extends our recent study in [12] from two dimensions and acoustic
scattering to the much more challenging three dimensions and electromagnetic
scattering.


title: Derived-Term Automata of Multitape Rational Expressions (Long version)

abstract:
  We introduce (weighted) rational expressions to denote series over Cartesian
products of monoids. To this end, we propose the operator $|$ to build
multitape expressions such as $(a^+|x + b^+|y)^*$. We define expansions, which
generalize the concept of derivative of a rational expression, but relieved
from the need of a free monoid. We propose an algorithm based on expansions to
build multitape automata from multitape expressions.


title:
The Australian Square Kilometre Array Pathfinder: Performance of the
  Boolardy Engineering Test Array

abstract:
  We describe the performance of the Boolardy Engineering Test Array (BETA),
the prototype for the Australian Square Kilometre Array Pathfinder telescope
ASKAP. BETA is the first aperture synthesis radio telescope to use phased array
feed technology, giving it the ability to electronically form up to nine
dual-polarization beams. We report the methods developed for forming and
measuring the beams, and the adaptations that have been made to the traditional
calibration and imaging procedures in order to allow BETA to function as a
multi-beam aperture synthesis telescope. We describe the commissioning of the
instrument and present details of BETA's performance: sensitivity, beam
characteristics, polarimetric properties and image quality. We summarise the
astronomical science that it has produced and draw lessons from operating BETA
that will be relevant to the commissioning and operation of the final ASKAP
telescope.


title:
Effective Capacity of Receive Antenna Selection MIMO-OSTBC Systems in
  Co-Channel Interference

abstract:
  In this paper, delay constrained performance of a multiple-input
multiple-output (MIMO) communication system in a dense environment with
co-channel interference is investigated. We apply orthogonal space-time block
coding (OSTBC) at the transmitter, and for alleviating the high complexity and
cost of the MIMO system, receive antenna selection (RAS) scheme is employed in
the downlink. Here, for simple and cheap mobile handsets, one antenna is chosen
at the receiver in each utilization of the channel. Under these assumptions, a
maximum constant arrival rate with the delay quality-of-service (QoS) guarantee
in a wireless channel is extracted. We obtain a closed-form solution for the
effective capacity of the MIMO-OSTBC channel with the RAS scheme in a
quasi-static Rayleigh fading conditions and co-channel interference. After all,
the numerical simulations are provided and verified the theoretical results.


title: $L^2$-Burau maps and $L^2$-Alexander torsions

abstract:
  It is well known that the Burau representation of the braid group can be used
to recover the Alexander polynomial of the closure of a braid. We define
$L^2$-Burau maps and use them to compute some $L^2$-Alexander torsions of
links. As an application, we prove that the $L^2$-Burau maps distinguish more
braids than the Burau representation.


title: Semantically Guided Depth Upsampling

abstract:
  We present a novel method for accurate and efficient up- sampling of sparse
depth data, guided by high-resolution imagery. Our approach goes beyond the use
of intensity cues only and additionally exploits object boundary cues through
structured edge detection and semantic scene labeling for guidance. Both cues
are combined within a geodesic distance measure that allows for
boundary-preserving depth in- terpolation while utilizing local context. We
model the observed scene structure by locally planar elements and formulate the
upsampling task as a global energy minimization problem. Our method determines
glob- ally consistent solutions and preserves fine details and sharp depth
bound- aries. In our experiments on several public datasets at different levels
of application, we demonstrate superior performance of our approach over the
state-of-the-art, even for very sparse measurements.


title: Nature of the Metallization Transition in Solid Hydrogen

abstract:
  We present an accurate study of the static-nucleus electronic energy band gap
of solid molecular hydrogen at high pressure. The excitonic and quasiparticle
gaps of the $C2/c$, $Pc$, $Pbcn$, and $P6_3/m$ structures at pressures of 250,
300, and 350~GPa are calculated using the fixed-node diffusion quantum Monte
Carlo (DMC) method. The difference between the mean-field and many-body band
gaps at the same density is found to be almost independent of system size and
can therefore be applied as a scissor correction to the mean-field gap of an
infinite system to obtain an estimate of the many-body gap in the thermodynamic
limit. By comparing our static-nucleus DMC energy gaps with available
experimental results, we demonstrate the important role played by nuclear
quantum effects in the electronic structure of solid hydrogen. Our DMC results
suggest that the metallization of high-pressure solid hydrogen occurs via a
structural phase transition rather than band gap closure.


title: On the norm attainment set of a bounded linear operator

abstract:
  In this paper we explore the properties of a bounded linear operator defined
on a Banach space, in light of operator norm attainment. Using Birkhoff-James
orthogonality techniques, we give a necessary condition for a bounded linear
operator attaining norm at a particular point of the unit sphere. We prove a
number of corollaries to establish the importance of our study. As part of our
exploration, we also obtain a characterization of smooth Banach spaces in terms
of operator norm attainment and Birkhoff-James orthogonality. Restricting our
attention to $ l_{p}^{2} (p \in \mathbb{N}\setminus \{ 1 \})$ spaces, we obtain
an upper bound for the number of points at which any linear operator, which is
not a scalar multiple of an isometry, may attain norm.


title:
A continuous and efficient fundamental price on the discrete order book
  grid

abstract:
  This paper develops a model of liquidity provision in financial markets by
adapting the Madhavan, Richardson, and Roomans (1997) price formation model to
realistic order books with quote discretization and liquidity rebates. We
postulate that liquidity providers observe a fundamental price which is
continuous, efficient, and can assume values outside the interval spanned by
the best quotes. We confirm the predictions of our price formation model with
extensive empirical tests on large high-frequency datasets of 100 liquid Nasdaq
stocks. Finally we use the model to propose an estimator of the fundamental
price based on the rebate adjusted volume imbalance at the best quotes and we
empirically show that it outperforms other simpler estimators.


title: Risk minimization by median-of-means tournaments

abstract:
  We consider the classical statistical learning/regression problem, when the
value of a real random variable Y is to be predicted based on the observation
of another random variable X. Given a class of functions F and a sample of
independent copies of (X, Y ), one needs to choose a function f from F such
that f(X) approximates Y as well as possible, in the mean-squared sense. We
introduce a new procedure, the so-called median-of-means tournament, that
achieves the optimal tradeoff between accuracy and confidence under minimal
assumptions, and in particular outperforms classical methods based on empirical
risk minimization.


title:
Exploiting the Bipartite Structure of Entity Grids for Document
  Coherence and Retrieval

abstract:
  Document coherence describes how much sense text makes in terms of its
logical organisation and discourse flow. Even though coherence is a relatively
difficult notion to quantify precisely, it can be approximated automatically.
This type of coherence modelling is not only interesting in itself, but also
useful for a number of other text processing tasks, including Information
Retrieval (IR), where adjusting the ranking of documents according to both
their relevance and their coherence has been shown to increase retrieval
effectiveness [34,37].
  The state of the art in unsupervised coherence modelling represents documents
as bipartite graphs of sentences and discourse entities, and then projects
these bipartite graphs into one-mode undirected graphs. However, one-mode
projections may incur significant loss of the information present in the
original bipartite structure. To address this we present three novel graph
metrics that compute document coherence on the original bipartite graph of
sentences and entities. Evaluation on standard settings shows that: (i) one of
our coherence metrics beats the state of the art in terms of coherence
accuracy; and (ii) all three of our coherence metrics improve retrieval
effectiveness because, as closer analysis reveals, they capture aspects of
document quality that go undetected by both keyword-based standard ranking and
by spam filtering. This work contributes document coherence metrics that are
theoretically principled, parameter-free, and useful to IR.


title:
The Gaia spectrophotometric standard stars survey - III. Short-term
  variability monitoring

abstract:
  We present the results of the short-term constancy monitoring of candidate
Gaia Spectrophotometric Standard Stars (SPSS). We obtained time series of
typically 1.24 hour - with sampling periods from 1-3 min to a few hours,
depending on the case - to monitor the constancy of our candidate SPSS down to
10 mmag, as required for the calibration of Gaia photometric data. We monitored
162 out of a total of 212 SPSS candidates. The observing campaign started in
2006 and finished in 2015, using 143 observing nights on nine different
instruments covering both hemispheres. Using differential photometry
techniques, we built light curves with a typical precision of 4 mmag, depending
on the data quality. As a result of our constancy assessment, 150 SPSS
candidates were validated against short term variability, and only 12 were
rejected because of variability including some widely used flux standards such
as BD+174708, SA 105-448, 1740346, and HD 37725.


title: Dynamics of complex-valued fractional-order neural networks

abstract:
  The dynamics of complex-valued fractional-order neuronal networks are
investigated, focusing on stability, instability and Hopf bifurcations.
Sufficient conditions for the asymptotic stability and instability of a steady
state of the network are derived, based on the complex system parameters and
the fractional order of the system, considering simplified neuronal
connectivity structures (hub and ring). In some specific cases, it is possible
to identify the critical values of the fractional order for which Hopf
bifurcations may occur. Numerical simulations are presented to illustrate the
theoretical findings and to investigate the stability of the limit cycles which
appear due to Hopf bifurcations.


title:
Uniqueness of vanishing viscosity mean curvature flow solution in two
  sub-Riemannian structures

abstract:
  Here we provide uniqueness of vanishing viscosity solutions to sub-Riemannian
mean curvature flow problem, which was known only far from characteristic
points or under special symmetry condition. We employ vanishing viscosity
approach and look for solutions as limit of solutions to approximating flow,
which is well defined also at characteristic points, and estimate the rate of
convergence of the approximating solutions. The results are provided in the
settings of both 3-dimensional rototranslation group $\text{SE}(2)$ and
Heisenberg group $\text{H}^1$ and they are particularly important due to their
relation to surface completion problem of model of the visual cortex.


title: Interactive Removal and Ground Truth for Difficult Shadow Scenes

abstract:
  A user-centric method for fast, interactive, robust and high-quality shadow
removal is presented. Our algorithm can perform detection and removal in a
range of difficult cases: such as highly textured and colored shadows. To
perform detection an on-the-fly learning approach is adopted guided by two
rough user inputs for the pixels of the shadow and the lit area. After
detection, shadow removal is performed by registering the penumbra to a
normalized frame which allows us efficient estimation of non-uniform shadow
illumination changes, resulting in accurate and robust removal. Another major
contribution of this work is the first validated and multi-scene category
ground truth for shadow removal algorithms. This data set containing 186 images
eliminates inconsistencies between shadow and shadow-free images and provides a
range of different shadow types such as soft, textured, colored and broken
shadow. Using this data, the most thorough comparison of state-of-the-art
shadow removal methods to date is performed, showing our proposed new algorithm
to outperform the state-of-the-art across several measures and shadow category.
To complement our dataset, an online shadow removal benchmark website is also
presented to encourage future open comparisons in this challenging field of
research.


title:
A Comparative Analysis of Community Detection Algorithms on Artificial
  Networks

abstract:
  Many community detection algorithms have been developed to uncover the
mesoscopic properties of complex networks. However how good an algorithm is, in
terms of accuracy and computing time, remains still open. Testing algorithms on
real-world network has certain restrictions which made their insights
potentially biased: the networks are usually small, and the underlying
communities are not defined objectively. In this study, we employ the
Lancichinetti-Fortunato-Radicchi benchmark graph to test eight state-of-the-art
algorithms. We quantify the accuracy using complementary measures and
algorithms' computing time. Based on simple network properties and the
aforementioned results, we provide guidelines that help to choose the most
adequate community detection algorithm for a given network. Moreover, these
rules allow uncovering limitations in the use of specific algorithms given
macroscopic network properties. Our contribution is threefold: firstly, we
provide actual techniques to determine which is the most suited algorithm in
most circumstances based on observable properties of the network under
consideration. Secondly, we use the mixing parameter as an easily measurable
indicator of finding the ranges of reliability of the different algorithms.
Finally, we study the dependency with network size focusing on both the
algorithm's predicting power and the effective computing time.


title:
New prospects for observing and cataloguing exoplanets in well detached
  binaries

abstract:
  This paper is devoted to study the circumstances favourable to detect
circumstellar and circumbinary planets in well detached binary-star-systems
using eclipse timing variations (ETVs). We investigated the dynamics of well
detached binary star systems with a star separation from 0.5 to 3~AU, to
determine the probability of the detection of such variations with ground based
telescopes and space telescopes (like former missions CoRoT and Kepler and
future space missions Plato, Tess and Cheops). For the chosen star separations
both dynamical configurations (circumstellar and circumbinary) may be
observable. We performed numerical simulations by using the full three-body
problem as dynamical model. The dynamical stability and the ETVs are
investigated by computing ETV maps for different masses of the secondary star
and the exoplanet (Earth, Neptune and Jupiter size). In addition we changed the
planet's and binary's eccentricities. We conclude that many amplitudes of ETVs
are large enough to detect exoplanets in binary star systems. As an
application, we prepared statistics of the catalogue of exoplanets in binary
star systems which we introduce in this article and compared the statistics
with our parameter-space which we used for our calculations. In addition to
these statistics of the catalogue we enlarged them by the investigation of well
detached binary star systems from several catalogues and discussed the
possibility of further candidates.


title: Bump-hunting in LHC ttbar events

abstract:
  We demonstrate that a purposefully normalised NNLO top pair invariant mass
differential spectrum can have very small theoretical uncertainty and, in
particular, a small sensitivity to the top quark mass. Such observable can thus
be a very effective bump-hunting tool for resonances decaying to top pair
events during LHC Run II and beyond. To illustrate how the approach works, we
concentrate on one specific example of current interest, namely, the possible
750 GeV di-gamma excess resonance Phi. Considering only theoretical
uncertainties, we demonstrate that it is possible to distinguish pp -> Phi ->
tt signals studied in the recent literature [Hespel, Maltoni and Vryonidou,
arXiv:1606.04149] from the pure SM background with very high significance.
Alternatively, in case of non-observation, a strong upper limit on the decay
rate Phi -> tt can be placed.


title:
Towards the Fundamental Quantum Limit of Linear Measurements of
  Classical Signals

abstract:
  The quantum Cram\'er-Rao bound (QCRB) sets a fundamental limit for the
measurement of classical signals with detectors operating in the quantum
regime. Using linear-response theory and the Heisenberg uncertainty relation,
we derive a general condition for achieving such a fundamental limit. When
applied to classical displacement measurements with a test mass, this condition
leads to an explicit connection between the QCRB and the Standard Quantum Limit
which arises from a tradeoff between the measurement imprecision and quantum
backaction; the QCRB can be viewed as an outcome of a quantum non-demolition
measurement with the backaction evaded. Additionally, we show that the test
mass is more a resource for improving measurement sensitivity than a victim of
the quantum backaction, which suggests a new approach to enhancing the
sensitivity of a broad class of sensors. We illustrate these points with laser
interferometric gravitational wave detectors.


title: The behavior of random reduced bases

abstract:
  We prove that the number of Siegel-reduced bases for a randomly chosen
$n$-dimensional lattice becomes, for $n \rightarrow \infty$, tightly
concentrated around its mean. We also show that most reduced bases behave as in
the worst-case analysis of lattice reduction.
  Comparing with experiment, these results suggest that most reduced bases
will, in fact, "very rarely" occur as an output of lattice reduction. The
concentration result is based on an analysis of the spectral theory of
Eisenstein series and uses (probably in a removable way) the Riemann
hypothesis.


title: On optimal investment with processes of long or negative memory

abstract:
  We consider the problem of utility maximization for investors with power
utility functions. Building on the earlier work Larsen et al. (2016), we prove
that the value of the problem is a Frechet-differentiable function of the drift
of the price process, provided that this drift lies in a suitable Banach space.
  We then study optimal investment problems with non-Markovian driving
processes. In such models there is no hope to get a formula for the achievable
maximal utility. Applying results of the first part of the paper we provide
first order expansions for certain problems involving fractional Brownian
motion either in the drift or in the volatility. We also point out how
asymptotic results can be derived for models with strong mean reversion.


title: On distances in generalized Sierpinski graphs

abstract:
  In this paper we propose formulas for the distance between vertices of a
generalized Sierpi\'{n}ski graph $S(G,t)$ in terms of the distance between
vertices of the base graph $G$. In particular, we deduce a recursive formula
for the distance between an arbitrary vertex and an extreme vertex of $S(G,t)$,
and we obtain a recursive formula for the distance between two arbitrary
vertices of $S(G,t)$ when the base graph is triangle-free. From these recursive
formulas, we provide algorithms to compute the distance between vertices of
$S(G,t)$. In addition, we give an explicit formula for the diameter and radius
of $S(G,t)$ when the base graph is a tree.


title: A model for distortions of polarisation-angle curves in radio pulsars

abstract:
  Some radio pulsar profiles (in particular those of millisecond pulsars
contain wide emission structures which cover large intervals of pulse phase.
Local distortions of an average curve of polarisation angle (PA) can be
identified in such profiles, and they are often found to be associated with
absorption features or narrow emission components. The features may be
interpreted as a convolution of a lateral profile of an emitter with a
microscopic radiation pattern of a non-negligible angular extent. We study a
model which assumes that such an extended microbeam of the X-mode curvature
radiation is spreading the radiation polarised at a fixed position angle within
an interval of pulse phase. The model is capable of interpreting the strongly
dissimilar polarisation of double notches in PSR B1821-24A (for which we
present new polarisation data from the Nancay Radio Telescope) and PSR
J0437-4715. It also explains a step-like change in PA observed at the
bifurcated trailing component in the profile of J0437-4715. A generic form of
the modelled PA distortion is a zigzag-shaped wiggle, which in the presence of
the second polarisation mode (O mode) can be magnified or transformed into a W-
or U-shaped deflection of a total net PA. The model's efficiency in
interpreting dissimilar polarisation effects provides further credence to the
stream-based (fan-beam) geometry of pulsar emission. It also suggests that the
microbeam width may not always be assumed negligible in comparison with the
angular scale of emissivity gradients in the emission region.


title:
Smart Contract Templates: foundations, design landscape and research
  directions

abstract:
  In this position paper, we consider some foundational topics regarding smart
contracts (such as terminology, automation, enforceability, and semantics) and
define a smart contract as an automatable and enforceable agreement. We explore
a simple semantic framework for smart contracts, covering both operational and
non-operational aspects, and describe templates and agreements for
legally-enforceable smart contracts, based on legal documents. Building upon
the Ricardian Contract, we identify operational parameters in the legal
documents and use these to connect legal agreements to standardised code. We
also explore the design landscape, including increasing sophistication of
parameters, increasing use of common standardised code, and long-term research.


title:
A path towards understanding the rotation-activity relation of M dwarfs
  with K2 mission, X-ray and UV data

abstract:
  We study the relation between stellar rotation and magnetic activity for a
sample of 134 bright, nearby M dwarfs observed in the Kepler Two-Wheel (K2)
mission during campaigns C0 to C4. The K2 lightcurves yield photometrically
derived rotation periods for 97 stars (79 of which without previous period
measurement), as well as various measures for activity related to cool spots
and flares. We find a clear difference between fast and slow rotators with a
dividing line at a period of ~10d at which the activity level changes abruptly.
All photometric diagnostics of activity (spot cycle amplitude, flare peak
amplitude and residual variability after subtraction of spot and flare
variations) display the same dichotomy, pointing to a quick transition between
a high-activity mode for fast rotators and a low-activity mode for slow
rotators. This unexplained behavior is reminiscent of a dynamo mode-change seen
in numerical simulations that separates a dipolar from a multipolar regime. A
substantial number of the fast rotators are visual binaries. A tentative
explanation is accelerated disk evolution in binaries leading to higher initial
rotation rates on the main-sequence and associated longer spin-down and
activity lifetimes. We combine the K2 rotation periods with archival X-ray and
UV data. X-ray, FUV and NUV detections are found for 26, 41, and 11 stars from
our sample, respectively. Separating the fast from the slow rotators, we
determine for the first time the X-ray saturation level separately for early-
and for mid-M stars.


title:
Photoexcited Carriers Recombination And Trapping In Spherical Vs Faceted
  TiO2 Nanoparticles

abstract:
  Nanoparticles of very small size (below 10 nm) of TiO2 material are nowadays
the functional building blocks of many developing technological applications.
Nano is clearly different from bulk or extended systems as regards surface
area, molecular binding properties, charge separation efficiency, electron/hole
transport, photochemical conversion properties, etc. In this work, we
investigate the life path of energy (excitons) and charge (electrons and holes)
carriers in anatase TiO2 nanoparticles of different size (2-3 nm) and shape
(faceted vs spherical), by means of a wide set of hybrid density functional
theory calculations. The attention is focused on the exciton/charge carriers
formation, separation, recombination, self-trapping processes, which are
analyzed in terms of structural deformations, energy gain or cost, charge
localization/delocalization and electronic transitions involved. The
computational models are corroborated by an extensive comparison with available
experimental data based on photoluminescence measurements, electron
paramagnetic resonance and transient absorption spectroscopies. Peculiar
differences are observed for spherical nanoparticles with respect to faceted
ones because of the higher disorder and larger diversity of coordination sites
present on the surface. For example, charge delocalization on several lattice
sites is more competitive with self-trapping processes in faceted than in
spherical nanoparticles. This relates to the fact that selective compression or
elongation of Ti-O bonds play a key role in determining the effectiveness of
trapping sites, with spherical nanoparticles being more flexible. Moreover,
hydroxyl groups on surface five-fold coordinated Ti sites are also found to be
good hole trapping sites.


title:
A new infinite family of non-abelian strongly real Beauville $p$-groups
  for every odd prime $p$

abstract:
  We prove that there exist infinitely many a non-abelian strongly real
Beauville $p$-group for every prime $p$. Previously only finitely many in the
case $p=2$ have been constructed.


title:
Dense semantic labeling of sub-decimeter resolution images with
  convolutional neural networks

abstract:
  Semantic labeling (or pixel-level land-cover classification) in ultra-high
resolution imagery (< 10cm) requires statistical models able to learn high
level concepts from spatial data, with large appearance variations.
Convolutional Neural Networks (CNNs) achieve this goal by learning
discriminatively a hierarchy of representations of increasing abstraction.
  In this paper we present a CNN-based system relying on an
downsample-then-upsample architecture. Specifically, it first learns a rough
spatial map of high-level representations by means of convolutions and then
learns to upsample them back to the original resolution by deconvolutions. By
doing so, the CNN learns to densely label every pixel at the original
resolution of the image. This results in many advantages, including i)
state-of-the-art numerical accuracy, ii) improved geometric accuracy of
predictions and iii) high efficiency at inference time.
  We test the proposed system on the Vaihingen and Potsdam sub-decimeter
resolution datasets, involving semantic labeling of aerial images of 9cm and
5cm resolution, respectively. These datasets are composed by many large and
fully annotated tiles allowing an unbiased evaluation of models making use of
spatial information. We do so by comparing two standard CNN architectures to
the proposed one: standard patch classification, prediction of local label
patches by employing only convolutions and full patch labeling by employing
deconvolutions. All the systems compare favorably or outperform a
state-of-the-art baseline relying on superpixels and powerful appearance
descriptors. The proposed full patch labeling CNN outperforms these models by a
large margin, also showing a very appealing inference time.


title: Universal mechanism for hybrid percolation transitions

abstract:
  Hybrid percolation transitions (HPTs) induced by cascading processes have
been observed in diverse complex systems such as $k$-core percolation,
breakdown on interdependent networks and cooperative epidemic spreading models.
Much effort has been devoted to describe the properties of HPTs of individual
systems. Yet the fundamental question about the possible universal mechanism
underlying those HPTs has not been investigated at a microscopic level. Here,
we find that the discontinuity in the order parameter in such HPTs results from
two steps: a durable critical branching (CB) and an explosive, supercritical
(SC) process. In a random network of $N$ nodes at the transition the CB process
persists for $O(N^{1/3})$ time and the remaining nodes become vulnerable. Those
vulnerable nodes are activated then in the short SC process. This crossover
mechanism and scaling behavior are universal for different HPT systems.


title: Curvature restrictions on a manifold with a flat Higgs bundle

abstract:
  We shall prove a semi-negative curvature property for a manifold with a flat
admissible Higgs bundle.


title: Exponential Family Embeddings

abstract:
  Word embeddings are a powerful approach for capturing semantic similarity
among terms in a vocabulary. In this paper, we develop exponential family
embeddings, a class of methods that extends the idea of word embeddings to
other types of high-dimensional data. As examples, we studied neural data with
real-valued observations, count data from a market basket analysis, and ratings
data from a movie recommendation system. The main idea is to model each
observation conditioned on a set of other observations. This set is called the
context, and the way the context is defined is a modeling choice that depends
on the problem. In language the context is the surrounding words; in
neuroscience the context is close-by neurons; in market basket data the context
is other items in the shopping cart. Each type of embedding model defines the
context, the exponential family of conditional distributions, and how the
latent embedding vectors are shared across data. We infer the embeddings with a
scalable algorithm based on stochastic gradient descent. On all three
applications - neural activity of zebrafish, users' shopping behavior, and
movie ratings - we found exponential family embedding models to be more
effective than other types of dimension reduction. They better reconstruct
held-out data and find interesting qualitative structure.


title:
Grown-in beryllium diffusion in indium gallium arsenide: An ab initio,
  continuum theory and kinetic Monte Carlo study

abstract:
  A roadblock in utilizing InGaAs for scaled-down electronic devices is its
anomalous dopant diffusion behavior; specifically, existing models are not able
to explain available experimental data on beryllium diffusion consistently. In
this paper, we propose a comprehensive model, taking self-interstitial
migration and Be interaction with Ga and In into account. Density functional
theory (DFT) calculations are first used to calculate the energy parameters and
charge states of possible diffusion mechanisms. Based on the DFT results,
continuum modeling and kinetic Monte Carlo simulations are then performed. The
model is able to reproduce experimental Be concentration profiles. Our results
suggest that the Frank-Turnbull mechanism is not likely, instead, kick-out
reactions are the dominant mechanism. Due to a large reaction energy
difference, the Ga interstitial and the In interstitial play different roles in
the kick-out reactions, contrary to what is usually assumed. The DFT
calculations also suggest that the influence of As on Be diffusion may not be
negligible.


title:
Isomonodromic deformations of irregular connections and stability of
  bundles

abstract:
  Let $G$ be a reductive affine algebraic group defined over $\mathbb C$, and
let $\nabla_0$ be a meromorphic $G$-connection on a holomorphic $G$-bundle
$E_0$, over a smooth complex curve $X_0$, with polar locus $P_0 \subset X_0$.
We assume that $\nabla_0$ is irreducible in the sense that it does not factor
through some proper parabolic subgroup of $G$. We consider the universal
isomonodromic deformation $(E_t\to X_t, \nabla_t, P_t)_{t\in \mathcal{T}}$ of
$(E_0\to X_0, \nabla_0, P_0)$, where $\mathcal{T}$ is a certain quotient of a
certain framed Teichm\"uller space we describe. We show that if the genus $g$
of $X_0$ satisfies $g\geq 2$, then for a general parameter $t\in \mathcal{T}$,
the $G$-bundle $E_t\to X_t$ is stable. For $g\geq 1$, we are able to show that
for a general parameter $t\in \mathcal{T}$, the $G$-bundle $E_t\to X_t$ is
semistable.


title:
Horn: A System for Parallel Training and Regularizing of Large-Scale
  Neural Networks

abstract:
  I introduce a new distributed system for effective training and regularizing
of Large-Scale Neural Networks on distributed computing architectures. The
experiments demonstrate the effectiveness of flexible model partitioning and
parallelization strategies based on neuron-centric computation model, with an
implementation of the collective and parallel dropout neural networks training.
Experiments are performed on MNIST handwritten digits classification including
results.


title: Graphs with Integer Matching Polynomial Roots

abstract:
  In this paper, we study graphs whose matching polynomial have only integer
zeros. A graph is matching integral if the zeros of its matching polynomial are
all integers. We characterize all matching integral traceable graphs.. We show
that apart from K7 n (E(C3) [ E(C4)) there is no connected k-regular matching
integral graph if k ? 2. It is also shown that if G is a graph with a perfect
matching, then its matching polynomial has a zero in the interval (0, 1].
Finally, we describe all claw-free matching integral graphs.


title:
YBa2Cu3O6+d-originated attraction force giving rise to Meissner effect
  at 300 K

abstract:
  The exposure of YBCO to an air atmosphere at first at pH2O = 110 Pa and then
at pH2O = 1 kPa has been used for uncharacteristic and unusual properties of
YBCO to be observed. Among them there was an increased reactivity of YBCO with
respect to water. Besides, it was experimentally obtained extremely excessive
weight gain of hydrated YBCO samples that was not corresponding to the quantity
of the absorbed water. Finally, we obtained the significant negative value of
the room-temperature (RT) magnetic susceptibility in conventional magnetic
study of the hydrated YBCO that was confirmed by the direct observation of
decreasing weight of the same samples that were suspended above the source of
controlled magnetic field (DC mode) at RT. All the results were explained on
the basis of an approximate idea that there is a certain source of attractive
force inside YBCO, acting on surrounding particles and bodies.


title:
Eclipse timing variations to detect possible Trojan planets in binary
  systems

abstract:
  This paper is devoted to study the circumstances favourable to detect Trojan
planets in close binary-star-systems by the help of eclipse timing variations
(ETVs). To determine the probability of the detection of such variations with
ground based telescopes and space telescopes (like former missions CoRoT and
Kepler and future space missions like Plato, Tess and Cheops), we investigated
the dynamics of binary star systems with a planet in tadpole motion. We did
numerical simulations by using the full three-body problem as dynamical model.
The stability and the ETVs are investigated by computing stability/ETV maps for
different masses of the secondary star and the Trojan planet. In addition we
changed the eccentricity of the possible Trojan planet. By the help of the
libration amplitude $\sigma$ we could show whether or not all stable objects
are moving in tadpole orbits. We can conclude that many amplitudes of ETVs are
large enough to detect Earth-like Trojan planets in binary star systems. As an
application, we prepared a list of possible candidates.


title:
Shape and Centroid Independent Clustring Algorithm for Crowd Management
  Applications

abstract:
  Clustering techniques play an important role in data mining and its related
applications. Among the challenging applications that require robust and
real-time processing are crowd management and group trajectory applications. In
this paper, a robust and low-complexity clustering algorithm is proposed. It is
capable of processing data in a manner that is shape and centroid independent.
The algorithm is of low complexity due to the novel technique to compute the
matrix power. The algorithm was tested on real and synthetic data and test
results are reported.


title: Dark Matter in $\gamma$ lines: Galactic Center vs dwarf galaxies

abstract:
  We provide CTA sensitivities to Dark Matter (DM) annihilation in $\gamma$-ray
lines, from the observation of the Galactic Center (GC) as well as, for the
first time, of dwarf Spheroidal galaxies (dSphs). We compare the GC reach with
that of dSphs as a function of a putative core radius of the DM distribution,
which is itself poorly known. We find that the currently best dSph candidates
constitute a more promising target than the GC, for core radii of one to a few
kpc. We use the most recent instrument response functions and background
estimations by CTA, on top of which we add the diffuse photon component. Our
analysis is of particular interest for TeV-scale electroweak multiplets as DM
candidates, such as the supersymmetric Wino and the Minimal Dark Matter
fiveplet, whose predictions we compare with our projected sensitivities.

categories: astro-ph.HE astro-ph.CO astro-ph.GA hep-ph


title: Tabling with Sound Answer Subsumption

abstract:
  Tabling is a powerful resolution mechanism for logic programs that captures
their least fixed point semantics more faithfully than plain Prolog. In many
tabling applications, we are not interested in the set of all answers to a
goal, but only require an aggregation of those answers. Several works have
studied efficient techniques, such as lattice-based answer subsumption and
mode-directed tabling, to do so for various forms of aggregation.
  While much attention has been paid to expressivity and efficient
implementation of the different approaches, soundness has not been considered.
This paper shows that the different implementations indeed fail to produce
least fixed points for some programs. As a remedy, we provide a formal
framework that generalises the existing approaches and we establish a soundness
criterion that explains for which programs the approach is sound.
  This article is under consideration for acceptance in TPLP.


title: An Improved Multileaving Algorithm for Online Ranker Evaluation

abstract:
  Online ranker evaluation is a key challenge in information retrieval. An
important task in the online evaluation of rankers is using implicit user
feedback for inferring preferences between rankers. Interleaving methods have
been found to be efficient and sensitive, i.e. they can quickly detect even
small differences in quality. It has recently been shown that multileaving
methods exhibit similar sensitivity but can be more efficient than interleaving
methods. This paper presents empirical results demonstrating that existing
multileaving methods either do not scale well with the number of rankers, or,
more problematically, can produce results which substantially differ from
evaluation measures like NDCG. The latter problem is caused by the fact that
they do not correctly account for the similarities that can occur between
rankers being multileaved. We propose a new multileaving method for handling
this problem and demonstrate that it substantially outperforms existing
methods, in some cases reducing errors by as much as 50%.


title: New word analogy corpus for exploring embeddings of Czech words

abstract:
  The word embedding methods have been proven to be very useful in many tasks
of NLP (Natural Language Processing). Much has been investigated about word
embeddings of English words and phrases, but only little attention has been
dedicated to other languages.
  Our goal in this paper is to explore the behavior of state-of-the-art word
embedding methods on Czech, the language that is characterized by very rich
morphology. We introduce new corpus for word analogy task that inspects
syntactic, morphosyntactic and semantic properties of Czech words and phrases.
We experiment with Word2Vec and GloVe algorithms and discuss the results on
this corpus. The corpus is available for the research community.


title: Conformal invariants associated with quadratic differentials

abstract:
  Z. Nehari developed a general technique for obtaining inequalities for
conformal maps and domain functions from contour integrals and the Dirichlet
principle. Given a harmonic function with singularity on a domain $R$, it
associates a monotonic functional of subdomains $D \subseteq R$. In the case
that $R$ is conformally equivalent to a disk, we extend Nehari's method by
associating a functional to any quadratic differential on $R$ with specified
singularities. Nehari's method corresponds to the special case that the
quadratic differential is of the form $(\partial q)^2$ for a singular harmonic
function $q$ on $R$. Besides being more general, our formulation is conformally
invariant, and has a particularly elegant equality statement. As an application
we give a one-parameter family of monotonic, conformally invariant functionals
which correspond to growth theorems for bounded univalent functions. These
generalize and interpolate the Pick growth theorems, which appear in a
conformally invariant form equivalent to a two-point distortion theorem of W.
Ma and D. Minda.


title: One-loop corrections for Higgs-portal dark matter

abstract:
  Models endowed with Higgs portals can probe into the hidden sectors of
particle physics while providing stable dark matter candidates. Previous
tree-level computations in such scenarios have shown that experimental bounds
constrain dark matter to a very narrow region in parameter space. Aiming at
improving the study of the implications of those constraints, we inspect
one-loop corrections to the annihilation cross section for scalar dark matter
into observable fermions. We find that these loop contributions might be enough
to drastically change those results by deforming in about 10% the allowed
parameter space for dark matter particles with masses even below 1 TeV. These
findings encourage further investigation.


title: Singularities of stable super-Brownian motion

abstract:
  We investigate in this work the spectrum of singularities of super-Brownian
motion with stable branching. The main purpose is to provide a uniform
description of the latter in high dimension $d\geq\tfrac{2}{\gamma-1}$,
presenting the singularities existing at every time t and characterising as
well the set of random times at which singularities of higher order appear. In
lower dimensions, we give a partial description of the singularities which
complement the recent study of the density by Mytnik and Wachtel.


title: Violet emission from bulk Si prompted by surface plasmon polaritons

abstract:
  Silicon has been long known as a poor light emitter due to its indirect band
gap and strong phonon-assisted decay of the excited states. Nevertheless, we
have revealed efficient quasi-monochromatic photoluminescence at 368 nm from
bulk silicon in the near-violet spectral range of the interband transition
SiE{\Gamma}1 even at room temperature. Optical and electron spectroscopy
experiments showed a clear relation of the emission to a surface plasmon
polariton (SPP) located on the SiO/Si interface. The presented results
demonstrate that the unveiled luminescence is an effect of creation and decay
of the SPP being a mixture of the surface plasmon, light, and the bulk
interband transition. The SPP evolves in the silicon layer with a thickness of
the order of the near-violet wave penetration depth (~80 nm) and is
characterized by high excitation amplitude due to its hybrid nature. The effect
seems to be easily applicable in developing near-violet light sources based on
the existing Si-technology.


title: Bayes Linear Methods for Large-Scale Network Search

abstract:
  Consider the problem of searching a large set of items, such as emails, for a
small set which are relevant to a given query. This can be implemented in a
sequential manner whereby we use knowledge from earlier items that we have
screened to help us choose future items in an informed way. Often the items we
are searching have an underlying network structure: for example emails can be
related to a network of participants, where an edge in the network relates to
the presence of a communication between those two participants. Recent work by
Dimitrov, Kress and Nevo has shown that using the information about the network
structure together with a modelling assumption that relevant items and
participants are likely to cluster together, can greatly increase the rate of
screening relevant items. However their approach is computationally expensive
and thus limited in applicability to small networks. Here we show how Bayes
Linear methods provide a natural approach to modelling such data; that they
output posterior summaries that are most relevant to heuristic policies for
choosing future items; and that they can easily be applied to large-scale
networks. Both on simulated data, and data from the Enron Corpus, Bayes Linear
approaches are shown to be applicable to situations where the method of
Dimitrov et al. is infeasible; and give substantially better performance than
methods that ignore the network structure.


title: Alternating sums concerning multiplicative arithmetic functions

abstract:
  We deduce asymptotic formulas for the alternating sums $\sum_{n\le x}
(-1)^{n-1} f(n)$ and $\sum_{n\le x} (-1)^{n-1} \frac1{f(n)}$, where $f$ is one
of the following classical multiplicative arithmetic functions: Euler's totient
function, the Dedekind function, the sum-of-divisors function, the divisor
function, the gcd-sum function. We also consider analogs of these functions,
which are associated to unitary and exponential divisors, and other special
functions. Some of our results improve the error terms obtained by
Bordell\`{e}s and Cloitre. We formulate certain open problems.


title: The Storage And Analytics Potential Of HBase Over The Cloud: A Survey

abstract:
  Apache HBase, a mainstay of the emerging Hadoop ecosystem, is a NoSQL
key-value and column family hybrid database which, unlike a traditional RDBMS,
is intentionally designed to scalably host large, semistructured, and
heterogeneous data. Prime examples of such data are biosignals which are
characterized by large volume, high volatility, and inherent
multidimensionality. This paper reviews how biomedical engineering has recently
taken advantage of HBase, with an emphasis over cloud, in order to reliably
host cardiovascular and respiratory time series. Moreover, the deployment of
offline biomedical analytics over HBase is explored.


title: CUHK & ETHZ & SIAT Submission to ActivityNet Challenge 2016

abstract:
  This paper presents the method that underlies our submission to the untrimmed
video classification task of ActivityNet Challenge 2016. We follow the basic
pipeline of temporal segment networks and further raise the performance via a
number of other techniques. Specifically, we use the latest deep model
architecture, e.g., ResNet and Inception V3, and introduce new aggregation
schemes (top-k and attention-weighted pooling). Additionally, we incorporate
the audio as a complementary channel, extracting relevant information via a CNN
applied to the spectrograms. With these techniques, we derive an ensemble of
deep models, which, together, attains a high classification accuracy (mAP
$93.23\%$) on the testing set and secured the first place in the challenge.


title: Tracking the Digital Footprints to Scholarly Articles from Social Media

abstract:
  Scholarly articles are discussed and shared on social media, which generates
altmetrics. On the opposite side, what is the impact of social media on the
dissemination of scholarly articles and how to measure it? What are the
visiting patterns? Investigating these issues, the purpose of this study is to
seek a solution to fill the research gap, specifically, to explore the dynamic
visiting patterns directed by social media, and examine the effects of social
buzz on the article visits. Using the unique real referral data of 110
scholarly articles, which are daily updated in a 90-day period, this paper
proposes a novel method to make analysis. We find that visits from social media
are fast to accumulate but decay rapidly. Twitter and Facebook are the two most
important social referrals that directing people to scholarly articles, the two
are about the same and account for over 95% of the total social referral
directed visits. There is synchronism between tweets and tweets resulted
visits. Social media and open access are playing important roles in
disseminating scholarly articles and promoting public understanding science,
which are confirmed quantitatively for the first time with real data in this
study.


title:
Anatomy of quantum critical wave functions in dissipative impurity
  problems

abstract:
  Quantum phase transitions reflect singular changes taking place in a
many-body ground state, however, computing and analyzing large-scale critical
wave functions constitutes a formidable challenge. New physical insights into
the sub-Ohmic spin-boson model are provided by the coherent state expansion
(CSE), which represents the wave function by a linear combination of
classically displaced configurations. We find that the distribution of
low-energy displacements displays an emergent symmetry in the absence of
spontaneous symmetry breaking, while experiencing strong fluctuations of the
order parameter near the quantum critical point. Quantum criticality provides
two strong fingerprints in critical low-energy modes: an algebraic decay of the
average displacement and a constant universal average squeezing amplitude.
These observations, confirmed by extensive variational matrix product states
(VMPS) simulations and field theory arguments, offer precious clues into the
microscopics of critical many-body states in quantum impurity models.


title: A simple proof of almost percolation on G(n;p)

abstract:
  We consider bootstrap percolation on the binomial random graph $G(n,p)$ with
infection threshold $r\in \mathbb{N}$, an infection process which starts from a
set of initially infected vertices and in each step every vertex with at least
$r$ infected neighbours becomes infected. We improve the results of Janson, \L
uczak, Turova, and Valier (2012) by strengthening the probability bounds on the
number of infected vertices at the end of the process, using simple arguments
based on martingales and giant components.


title:
A study on partial dynamic equation on time scales involving derivatives
  of polynomials

abstract:
  Let $\mathbf{P}_b^m(x)$ be a $2m+1-$degree integer-valued polynomial in
$x,b$. Let be a two-dimensional time scale $\Lambda^2 = \mathbb{T}_1 \times
\mathbb{T}_2 = \{t=(x, b) \colon \; x\in\mathbb{T}_1, \; b\in\mathbb{T}_2 \}$.
Let be $\mathbb{T}_1 = \mathbb{T}_2$. In this manuscript we derive and discuss
the following partial dynamic equation on time scales. For every
$t\in\mathbb{T}_1, \; x,b\in \Lambda^2, \; m = const, \; m\in\mathbb{N}$ \[
(t^{2m+1})^{\Delta} = \frac{\partial \mathbf{P}_b^m(x)}{\Delta x} \bigg |_{x =
t, \; b = \sigma(t)} + \frac{\partial \mathbf{P}_b^m(x)}{\Delta b}\bigg |_{x =
t, \; b = t}, \] where $\sigma(t) > t$ is forward jump operator. In addition,
we discuss various derivative operators in context of partial cases of above
equation, we show finite difference, classical derivative, $q-$derivative,
$q-$power derivative on behalf of it.