title: Analytic Models of Brown Dwarfs and The Substellar Mass Limit

abstract:
  We present the current status of the analytic theory of brown dwarf evolution
and the lower mass limit of the hydrogen burning main sequence stars. In the
spirit of a simplified analytic theory we also introduce some modifications to
the existing models. We give an exact expression for the pressure of an ideal
non-relativistic Fermi gas at a finite temperature, therefore allowing for
non-zero values of the degeneracy parameter ($\psi = \frac{kT}{\mu_{F}}$, where
$\mu_{F}$ is the Fermi energy). We review the derivation of surface luminosity
using an entropy matching condition and the first-order phase transition
between the molecular hydrogen in the outer envelope and the partially-ionized
hydrogen in the inner region. We also discuss the results of modern simulations
of the plasma phase transition, which illustrate the uncertainties in
determining its critical temperature. Based on the existing models and with
some simple modification we find the maximum mass for a brown dwarf to be in
the range $0.064M_\odot-0.087M_\odot$. An analytic formula for the luminosity
evolution allows us to estimate the time period of the non-steady state (i.e.,
non-main sequence) nuclear burning for substellar objects. Standard models also
predict that stars that are just above the substellar mass limit can reach an
extremely low luminosity main sequence after at least a few million years of
evolution, and sometimes much longer. We estimate that $\simeq 11 \%$ of stars
take longer than $10^7$ yr to reach the main-sequence, and $\simeq 5 \%$ of
stars take longer than $10^8$ yr.


title: Enclosed mmWave Wearable Networks: Feasibility and Performance

abstract:
  This paper investigates the feasibility of mmWave frequencies for personal
networks of wireless wearable devices in enclosed settings (e.g., commuter
trains, subways, airplanes, airports, or offices). At these frequencies,
specular reflections off surfaces are expected to contribute intended signal
power and, simultaneously, to aggravate the interference at the receivers.
Meanwhile, blockages by obstacles and people---including the individuals
wearing the devices---are expected to shield receivers from interference. With
the aid of stochastic geometry and random shape theory, we assess the interplay
of surface reflections and blockages for dense deployments of wearable networks
equipped with directional antenna arrays in relevant indoor settings.


title:
Nonlinear Stabilization via Control Contraction Metrics: a
  Pseudospectral Approach for Computing Geodesics

abstract:
  Real-time nonlinear stabilization techniques are often limited by inefficient
or intractable online and/or offline computations, or a lack guarantee for
global stability. In this paper, we explore the use of Control Contraction
Metrics (CCM) for nonlinear stabilization because it offers tractable offline
computations that give formal guarantees for global stability. We provide a
method to solve the associated online computation for a CCM controller - a
pseudospectral method to find a geodesic. Through a case study of a stiff
nonlinear system, we highlight two key benefits: (i) using CCM for nonlinear
stabilization and (ii) rapid online computations amenable to real-time
implementation. We compare the performance of a CCM controller with other
popular feedback control techniques, namely the Linear Quadratic Regulator
(LQR) and Nonlinear Model Predictive Control (NMPC). We show that a CCM
controller using a pseudospectral approach for online computations is a middle
ground between the simplicity of LQR and stability guarantees for NMPC.


title:
Categorical actions and multiplicities in the Deligne category
  $\underline{Rep}(GL_t)$

abstract:
  We study the categorical type A action on the Deligne category
$\mathcal{D}_t=\underline{Rep}(GL_t)$ (here $t \in \mathbb{C}$) and its
"abelian envelope" $\mathcal{V}_t$ constructed in arXiv:1511.07699.
  For $t \in \mathbb{Z}$, this action categorifies an action of the Lie algebra
$\mathfrak{sl}_{\mathbb{Z}}$ on the tensor product of the Fock space
$\mathfrak{F}$ with $\mathfrak{F}_t^{\vee}$, its restricted dual "shifted" by
$t$, as was suggested by I. Losev. In fact, this action makes the category
$\mathcal{V}_t$ the tensor product (in the sense of Losev and Webster,
arXiv:1303.1336) of categorical $\mathfrak{sl}_{\mathbb Z}$-modules $Pol$ and
$Pol_t^{\vee}$. The latter categorify $\mathfrak{F}$ and
$\mathfrak{F}_t^{\vee}$ respectively, the underlying category in both cases
being the category of stable polynomial representations (also known as the
category of Schur functors), as described by Hong and Yacobi, arXiv:1101.2456
(see also Losev, arXiv:1209.1067).
  When $t \notin \mathbb Z$, the Deligne category $\mathcal{D}_t$ is abelian
semisimple, and the type A action induces a categorical action of
$\mathfrak{sl}_{\mathbb{Z}} \times \mathfrak{sl}_{\mathbb{Z}}$. This action
categorifies the $\mathfrak{sl}_{\mathbb{Z}} \times \mathfrak{sl}_{\mathbb{Z}
}$-module $\mathfrak{F} \boxtimes \mathfrak{F}^{\vee}$, making $\mathcal{D}_t$
the exterior tensor product of the categorical $\mathfrak{sl}_{\mathbb
Z}$-modules $Pol$, $Pol^{\vee}$.
  Along the way we establish a new relation between the Kazhdan-Lusztig
coefficients and the multiplicities in the standard filtrations of tilting
objects in $\mathcal{V}_t$.


title: Predicting the Popularity of GitHub Repositories

abstract:
  GitHub is the largest source code repository in the world. It provides a
git-based source code management platform and also many features inspired by
social networks. For example, GitHub users can show appreciation to projects by
adding stars to them. Therefore, the number of stars of a repository is a
direct measure of its popularity. In this paper, we use multiple linear
regressions to predict the number of stars of GitHub repositories. These
predictions are useful both to repository owners and clients, who usually want
to know how their projects are performing in a competitive open source
development market. In a large-scale analysis, we show that the proposed models
start to provide accurate predictions after being trained with the number of
stars received in the last six months. Furthermore, specific models---generated
using data from repositories that share the same growth trends---are
recommended for repositories with slow growth and/or for repositories with less
stars. Finally, we evaluate the ability to predict not the number of stars of a
repository but its rank among the GitHub repositories. We found a very strong
correlation between predicted and real rankings (Spearman's rho greater than
0.95).


title: Fibrations in $\infty$-category theory

abstract:
  In this short expository note, we discuss, with plenty of examples, the
bestiary of fibrations in quasicategory theory. We underscore the simplicity
and clarity of the constructions these fibrations make available to end-users
of higher category theory.


title: Suppression of clock shifts at field-insensitive transitions

abstract:
  We show that it is possible to significantly reduce quadrupole and tensor
polarizability shifts of a clock transition by operating at a judiciously
chosen field-insensitive point. In some cases shifts are almost completely
eliminated making the transition an effective J = 0 to J = 0 candidate. This
significantly improves the feasibility of a recent proposal for clock operation
with large ion crystals. For such multi-ion clocks, geometric constraints and
selection rules naturally divide clock operation into two categories based on
the orientation of the magnetic field. We discuss the limitations imposed on
each type and how calibrations might be carried out for clock operation.


title: Backstepping Control of the One-Phase Stefan Problem

abstract:
  In this paper, a backstepping control of the one-phase Stefan Problem, which
is a 1-D diffusion Partial Differential Equation (PDE) defined on a time
varying spatial domain described by an ordinary differential equation (ODE), is
studied. A new nonlinear backstepping transformation for moving boundary
problem is utilized to transform the original coupled PDE-ODE system into a
target system whose exponential stability is proved. The full-state boundary
feedback controller ensures the exponential stability of the moving interface
to a reference setpoint and the ${\cal H}_1$-norm of the distributed
temperature by a choice of the setpint satisfying given explicit inequality
between initial states that guarantees the physical constraints imposed by the
melting process.


title:
Space-Efficient Construction of Compressed Indexes in Deterministic
  Linear Time

abstract:
  We show that the compressed suffix array and the compressed suffix tree of a
string $T$ can be built in $O(n)$ deterministic time using $O(n\log\sigma)$
bits of space, where $n$ is the string length and $\sigma$ is the alphabet
size. Previously described deterministic algorithms either run in time that
depends on the alphabet size or need $\omega(n\log \sigma)$ bits of working
space. Our result has immediate applications to other problems, such as
yielding the first linear-time LZ77 and LZ78 parsing algorithms that use $O(n
\log\sigma)$ bits.


title:
Spectrum-based Software Fault Localization: A Survey of Techniques,
  Advances, and Challenges

abstract:
  Despite being one of the most basic tasks in software development, debugging
is still performed in a mostly manual way, leading to high cost and low
performance. To address this problem, researchers have studied promising
approaches, such as Spectrum-based Fault Localization (SFL) techniques, which
pinpoint program elements more likely to contain faults. This survey discusses
the state-of-the-art of SFL, including the different techniques that have been
proposed, the type and number of faults they address, the types of spectra they
use, the programs they utilize in their validation, the testing data that
support them, and their use at industrial settings. Notwithstanding the
advances, there are still challenges for the industry to adopt these
techniques, which we analyze in this paper. SFL techniques should propose new
ways to generate reduced sets of suspicious entities, combine different spectra
to fine-tune the fault localization ability, use strategies to collect
fine-grained coverage levels from suspicious coarser levels for balancing
execution costs and output precision, and propose new techniques to cope with
multiple-fault programs. Moreover, additional user studies are needed to
understand better how SFL techniques can be used in practice. We conclude by
presenting a concept map about topics and challenges for future research in
SFL.


title:
Computation of quandle 2-cocycle knot invariants without explicit
  2-cocycles

abstract:
  We explore a knot invariant derived from colorings of corresponding
$1$-tangles with arbitrary connected quandles. When the quandle is an abelian
extension of a certain type the invariant is equivalent to the quandle
$2$-cocycle invariant. We construct many such abelian extensions using
generalized Alexander quandles without explicitly finding $2$-cocycles. This
permits the construction of many $2$-cocycle invariants without exhibiting
explicit $2$-cocycles. We show that for connected generalized Alexander
quandles the invariant is equivalent to Eisermann's knot coloring polynomial.
Computations using this technique show that the $2$-cocycle invariant
distinguishes all of the oriented prime knots up to 11 crossings and most
oriented prime knots with 12 crosssings including classification by symmetry:
mirror images, reversals, and reversed mirrors.


title: Dynamic Hysteresis Probes High-{\beta} Nanolaser Emission Regimes

abstract:
  The quest for an integrated light source that promises high energy efficiency
and fast modulation for high-performance photonic circuits has led to the
development of room-temperature telecom-wavelength nanoscale laser with high
spontaneous emission factors, \beta. The coherence characterization of this
type of lasers is inherently difficult with the conventional measurement of
output light intensity versus input pump intensity due to the diminishing kink
in the measurement curve. We demonstrate the transition from chaotic to
coherent emission of a high-{\beta} pulse-pump metallo-dielectric nanolaser can
be determined by examining the width of a second order intensity correlation
peak, which shrinks below and broadens above threshold. Photon fluctuation
study, first one ever reported for this type of nanolaser, confirms the
validity of this measurement technique. Additionally, we show that the width
variation above threshold results from the delayed threshold phenomenon,
providing the first indirect observation of dynamical hysteresis in a
nanolaser.


title: Tight detection efficiency bounds of Bell tests in no-signaling theories

abstract:
  No-signaling theories, which can contain nonlocal correlations stronger than
classical correlations but limited by the no-signaling condition, have deepened
our understanding of the quantum theory. In principle, the nonlocality of these
theories can be verified via Bell tests. In practice, however, inefficient
detectors may make Bell tests unreliable, which is called the detection
efficiency loophole. In this work, we show almost tight lower and upper bounds
of the detector efficiency requirement for demonstrating the nonlocality of
no-signaling theories, by designing a general class of Bell tests. In
particular, we show tight bounds for two scenarios: the bipartite case and the
multipartite case with a large number of parties. To some extent, these tight
efficiency bounds quantify the nonlocality of no-signaling theories.
Furthermore, our result shows that the detector efficiency can be arbitrarily
low even for Bell tests with two parties, by increasing the number of
measurement settings. Our work also sheds light on the detector efficiency
requirement for showing the nonlocality of the quantum theory.


title: The red dwarf pair GJ65AB: inflated, spinning twins of Proxima

abstract:
  The nearby red dwarf binary GJ65AB (UB+BL Ceti, M5.5Ve+M6Ve) is a cornerstone
system to probe the physics of very low mass stars. We present new
interferometric measurements of the angular diameters of the two components of
GJ65AB with the PIONIER instrument in the H band: thetaUD (A) = 0.558 +/- 0.008
+/- 0.020 mas and thetaUD (B) = 0.539 +/- 0.009 +/- 0.020 mas. They translate
into limb-darkened angular diameters of LD (A) = 0.573 +/- 0.021 mas and LD (B)
= 0.554 +/- 0.022 mas. From the known parallax, the radii are R(A) = 0.165 +/-
0.006 Rsun and R(B) = 0.159 +/- 0.006 Rsun (sigma(R)/R = 4%). We also observed
GJ65AB with the VLT/NACO adaptive optics and refine the orbital parameters and
infrared magnitudes of the system. We derive masses for the two components of
m(A) = 0.1225 +/- 0.0043 Msun and m(B) = 0.1195 +/- 0.0043 Msun (sigma(m)/m =
4%). To derive the radial and rotational velocities of the two stars, as well
as their relative metallicity with respect to Proxima, we also present new
individual UVES high resolution spectra. Placing GJ65 A&B in the mass-radius
diagram shows that their radii are larger respectively by 14 +/- 4% and 12 +/-
4% compared to expectations from the models by Baraffe et al. (2015). Following
Chabrier et al. (2007), we propose that this discrepancy is caused by the
inhibition of convective energy transport by a strong internal magnetic field
generated by dynamo effect in these two fast rotating stars. A comparison with
the almost identical twin but slowly-rotating Proxima strengthens this
hypothesis, as the radius of Proxima does not appear inflated compared to
models.


title: Ergodic Spectral Efficiency in MIMO Cellular Networks

abstract:
  This paper shows how the application of stochastic geometry to the analysis
of wireless networks is greatly facilitated by (i) a clear separation of time
scales, (ii) the abstraction of small-scale effects via ergodicity, and (iii)
an interference model that reflects the receiver's lack of knowledge of how
each individual interference term is faded. These procedures render the
analysis both more manageable and more precise, as well as more amenable to the
incorporation of subsequent features. In particular, the paper presents
analytical characterizations of the ergodic spectral efficiency of cellular
networks with single-user multiple-input multiple-output (MIMO) and
sectorization. These characterizations, in the form of easy-to-evaluate
expressions, encompass the coverage, the distribution of spectral efficiency
over the network locations, and the average thereof.


title: Constraining the generalized uncertainty principle with cold atoms

abstract:
  Various theories of quantum gravity predict the existence of a minimum length
scale, which implies the Planck-scale modifications of the Heisenberg
uncertainty principle to a so-called generalized uncertainty principle (GUP).
Previous studies of the GUP focused on its implications for high-energy
physics, cosmology, and astrophysics. Here, the application of the GUP to
low-energy quantum systems, and particularly cold atoms, is studied. Results
from the $^{87}$Rb atom recoil experiment are used to set upper bounds on
parameters in three different GUP proposals. A $10^{14}$-level bound on the
Ali-Das-Vagenas proposal is found, which is the second best bound so far. A
$10^{26}$-level bound on Maggiore's proposal is obtained, which turns out to be
the best available bound on it.


title: Infinite order corks via handle diagrams

abstract:
  The author recently proved the existence of an infinite order cork: a
compact, contractible submanifold $C$ of a 4-manifold and an infinite order
diffeomorphism $f$ of $\partial C$ such that cutting out $C$ and regluing it by
distinct powers of $f$ yields pairwise nondiffeomorphic manifolds. The present
paper exhibits the first handle diagrams of this phenomenon, by translating the
earlier proof into this language (for each of the infinitely many corks arising
in the first paper). The cork twists in these papers are twists on
incompressible tori. We give conditions guaranteeing that such twists do not
change the diffeomorphism type of a 4-manifold, partially answering a question
from the original paper. We also show that the "$\delta$-moves" recently
introduced by Akbulut are essentially equivalent to torus twists.


title:
Segment-Scale, Force-Level Theory of Mesoscopic Dynamic Localization and
  Entropic Elasticity in Entangled Chain Polymer Liquids

abstract:
  We develop a segment-scale, force-based theory for the breakdown of the
unentangled Rouse model and subsequent emergence of isotropic mesoscopic
localization and entropic elasticity in chain polymer liquids in the absence of
ergodicity-restoring anisotropic reptation motion. The theory is formulated in
terms of a conformational N-dynamic-order-parameter Generalized Langevin
Equation approach. It is implemented using a field-theoretic Gaussian thread
model of polymer structure and closed in a universal manner at the level of the
chain dynamic second moment matrix. The physical idea is that the isotropic
Rouse model fails due to the dynamical emergence of time-persistent
intermolecular contacts determined by the combined influence of local chain
uncrossability, long range polymer connectivity and a self-consistent treatment
of chain motion and the dynamic forces that hinder it. For long chain melts,
the mesoscopic localization length (tube diameter) and emergent elasticity
predictions are in near quantitative agreement with experiment. Moreover, the
onset chain length scales with the semi-dilute crossover concentration with a
realistic numerical prefactor. Distinctive predictions are made for various
off-diagonal correlation functions that quantify the full spatial structure of
the dynamically localized polymer conformation. As the local uncrossability
constraint and/or intrachain bonding spring are softened, the tube diameter is
predicted to swell until it reaches the chain radius-of-gyration at which point
entanglement localization vanishes in a discontinuous manner. A full dynamic
phase diagram for the destruction of mesoscopic localization is constructed,
which is qualitatively consistent with simulations and the classical concept of
an entanglement degree of polymerization.


title:
A versatile rotary-stage high frequency probe station for studying
  magnetic films and devices

abstract:
  We present a rotary-stage microwave probe station suitable for magnetic films
and spintronic devices. Two stages, one for field rotation from parallel to
perpendicular to the sample plane (Out-of-Plane) and the other intended for
field rotation within the sample plane (In-Plane) have been designed. The
sample, probes and micro positioners are rotated simultaneously with the
stages, which allows the field orientation to cover $\theta$ from 0 to
$90^{\circ}$ and $\varphi$ from 0 to $360^{\circ}$. $\theta$ and $\varphi$
being the angle between the direction of current flow and field in a
Out-of-Plane and an In-Plane rotation, respectively. The operation frequency is
up to 40 GHz and the magnetic field up to 1 T. The sample holder, vision system
and probe assembly are compactly designed for the probes to land on a wafer
with diameter up to 3$\,$cm. Using homemade multi-pin probes and commercially
available high frequency probes, several applications including 4-probe DC
measurements, the determination of domain wall velocity and spin transfer
torque ferromagnetic resonance are demonstrated.


title:
A BCMP Network Approach to Modeling and Controlling Autonomous
  Mobility-on-Demand Systems

abstract:
  In this paper we present a queueing network approach to the problem of
routing and rebalancing a fleet of self-driving vehicles providing on-demand
mobility within a capacitated road network. We refer to such systems as
autonomous mobility-on-demand systems, or AMoD. We first cast an AMoD system
into a closed, multi-class BCMP queueing network model. Second, we present
analysis tools that allow the characterization of performance metrics for a
given routing policy, in terms, e.g., of vehicle availabilities, and first and
second order moments of vehicle throughput. Third, we propose a scalable method
for the synthesis of routing policies, with performance guarantees in the limit
of large fleet sizes. Finally, we validate our theoretical results on a case
study of New York City. Collectively, this paper provides a unifying framework
for the analysis and control of AMoD systems, which subsumes earlier Jackson
and network flow models, provides a quite large set of modeling options (e.g.,
the inclusion of road capacities and general travel time distributions), and
allows the analysis of second and higher-order moments for the performance
metrics.


title:
Modelling resource contention in multi-robot task allocation problems
  with uncertain timing

abstract:
  This paper proposes an analytical framework for modelling resource contention
in multi-robot systems, where the travel times and task durations are
uncertain. It uses several approximation methods to quickly and accurately
calculate the probability distributions describing the times at which the tasks
start and finish. Specific contributions include exact and fast approximation
methods for calculating the probability of a set of independent normally
distributed random events occurring in a given order, a method for calculating
the most likely and n-th most likely orders of occurrence for a set of
independent normally distributed random events that have equal standard
deviations, and a method for approximating the conditional probability
distributions of the events given a specific order of the events. The complete
framework is shown to be faster than a Monte Carlo approach for the same
accuracy in two multi-robot task allocation problems. In addition, the
importance of incorporating uncertainty is demonstrated through a comparison
with a deterministic method. This is a general framework that is agnostic to
the optimisation method and objective function used, and is applicable to a
wide range of problems.


title: Newman-Janis Ansatz in conformastatic spacetimes

abstract:
  The Newman-Janis Ansatz was used first to obtain the stationary Kerr metric
from the static Schwarzschild metric. Many works have been devoted to
investigate the physical significance of this Ansatz, but no definite answer
has been given so far. We show that this Ansatz can be applied in general to
conformastatic vacuum metrics, and leads to stationary generalizations which,
however, do not preserve the conformal symmetry. We investigate also the
particular case when the seed solution is given by the Schwarzschild spacetime
and show that the resulting rotating configuration does not correspond to a
vacuum solution, even in the limiting case of slow rotation. In fact, it
describes in general a relativistic fluid with anisotropic pressure and heat
flux. This implies that the Newman-Janis Ansatz strongly depends on the choice
of representation for the seed solution. We interpret this result as as a
further indication of its applicability limitations.


title: Grid-Based Multichannel Access in Vehicular Networks

abstract:
  In vehicular networks, vehicles exchange messages with each other as well as
infrastructure to prevent accidents or enhance driver's and passenger's
experience. In this paper, we propose a grid-based multichannel access scheme
to enhance the performance of a vehicular network. To determine the feasibility
of our scheme, we obtained preliminary results using the OPNET simulation tool.


title:
On $C^1$, $C^2$, and weak type-$(1,1)$ estimates for linear elliptic
  operators

abstract:
  We show that any weak solution to elliptic equations in divergence form is
continuously differentiable provided that the modulus of continuity of
coefficients in the $L^1$-mean sense satisfies the Dini condition. This in
particular answers a question recently raised by Yanyan Li and allows us to
improve a result of Brezis. We also prove a weak type-$(1,1)$ estimate under a
stronger assumption on the modulus of continuity. The corresponding results for
non-divergence form equations are also established.


title: Mechanism Design for Value Maximizers

abstract:
  In many settings, money is a tool of exchange with minimal inherent utility
--- agents will spend it in a way that maximizes the value of goods received
subject to reasonable constraints, giving only second-order consideration to
the trade-off between value and price. While this perspective is commonly
captured in consumer choice theory, market equilibrium theory, and other
fields, it is markedly absent from the mechanism design literature --- agents
strategizing in a mechanism with money are almost always assumed to incorporate
money as an objective through quasilinear valuations. We study a simple model
of value maximizers that captures online advertisers and other agents who may
view money solely as a constraint, and study general questions of mechanism
design for such agents. We show that the feasible and optimal points faced by a
mechanism designer change dramatically from the quasilinear realm and lay a
foundation for a broader study of value maximization in mechanism design. Along
the way, we offer new insight into the generalized second price (GSP) auction
commonly used in Internet advertising. Through the lens of value maximization,
GSP metamorphosizes into a truthful auction, sound in its principles and
elegant in its simplicity.


title:
Time-domain pumping a quantum-critical charge-density-wave-ordered
  material

abstract:
  We determine the exact time-resolved photoemission spectroscopy for a nesting
driven charge-density-wave (described by the spinless Falicov-Kimball model
within dynamical mean-field theory). The pump-probe experiment involves two
light pulses: the first is an ultrashort intense pump pulse that excites the
system into nonequilibrium, and the second is a lower amplitude higher
frequency probe pulse that photoexcites electrons. We examine three different
cases: the strongly correlated metal, the quantum-critical charge density wave
and the critical Mott insulator. Our results show that the quantum critical
charge density wave has an ultra efficient relaxation channel that allows
electrons to be de-excited during the pump pulse, resulting in little net
excitation. In contrast, the metal and the Mott insulator show excitations that
are closer to what one expects from these systems. In addition, the pump field
produces spectral band narrowing, peak sharpening, and a spectral gap
reduction, all of which rapidly return to their field free values after the
pump is over.


title: Normality versus paracompactness in locally compact spaces

abstract:
  This note provides a correct proof of the result claimed by the second author
that locally compact normal spaces are collectionwise Hausdorff in certain
models obtained by forcing with a coherent Souslin tree. A novel feature of the
proof is the use of saturation of the non-stationary ideal on \omega_1, as well
as of a strong form of Chang's Conjecture. Together with other improvements,
this enables the characterization of locally compact hereditarily paracompact
spaces as those locally compact, hereditarily normal spaces that do not include
a copy of \omega_1.


title: Electric and magnetic multipoles and bond orders in excitonic insulators

abstract:
  We study the charge and spin density distributions of excitonic insulator
(EI) states in the tight-binding approximation. We first discuss the charge and
spin densities of the EI states when the valence and conduction bands are
composed of orthogonal orbitals in a single atom. We show that the anisotropic
charge or spin density distribution occurs in a unit cell (or atom) and a
higher rank electric or magnetic multipole moment becomes finite, indicating
that the EI state corresponds to the multipole order. A full description of the
multipole moments for the $s$, $p$, and $d$ orbitals is then given in general.
We find that, in contrast to the conventional density-wave states, the
modulation of the total charge or net magnetization does not appear in this
case. However, when the conduction and valence bands include the component of
the same orbital, the modulation of the total charge or net magnetization
appears, as in the conventional density-wave state. We also discuss the
electron density distribution in the EI state when the valence and conduction
bands are composed of orbitals located in different atoms. We show that the
excitonic ordering in this case corresponds to the bond order formation. Based
on the results thus obtained we discuss the EI states of real materials
recently reported.


title:
Management of Renewable Energy for A Shared Facility Controller in Smart
  Grid

abstract:
  This paper proposes an energy management scheme to maximize the use of solar
energy in the smart grid. In this context, a shared facility controller (SFC)
with a number of solar photovoltaic (PV) panels in a smart community is
considered that has the capability to schedule the generated energy for
consumption and trade to other entities. Particularly, a mechanism is designed
for the SFC to decide on the energy surplus, if there is any, that it can use
to charge its battery and sell to the households and the grid based on the
offered prices. In this regard, a hierarchical energy management scheme is
proposed with a view to reduce the total operational cost to the SFC. The
concept of a virtual cost (VC) is introduced that aids the SFC to estimate its
future operational cost based on some available current information. The energy
management is conducted for three different cases and the optimal cost to the
SFC is determined for each case via the theory of maxima and minima. A
real-time algorithm is proposed to reach the optimal cost for all cases and
some numerical examples are provided to demonstrate the beneficial properties
of the proposed scheme.


title:
The semi-parametric Bernstein-von Mises theorem for regression models
  with symmetric errors

abstract:
  In a smooth semi-parametric model, the marginal posterior distribution for a
finite dimensional parameter of interest is expected to be asymptotically
equivalent to the sampling distribution of any efficient point-estimator. The
assertion leads to asymptotic equivalence of credible and confidence sets for
the parameter of interest and is known as the semi-parametric Bernstein-von
Mises theorem. In recent years, it has received much attention and has been
applied in many examples. We consider models in which errors with symmetric
densities play a role; more specifically, it is shown that the marginal
posterior distributions of regression coefficients in the linear regression and
linear mixed effect models satisfy the semi-parametric Bernstein-von Mises
assertion. As a consequence, Bayes estimators in these models achieve
frequentist inferential optimality, as expressed e.g. through Hajek's
convolution and asymptotic minimax theorems. Conditions for the prior on the
space of error densities are relatively mild and well-known constructions like
the Dirichlet process mixture of normal densities and random series priors
constitute valid choices. Particularly, the result provides an efficient
estimate of regression coefficients in the linear mixed effect model, for which
no other efficient point-estimator was known previously.


title: PFA(S)[S] and countably compact spaces

abstract:
  We show a number of undecidable assertions concerning countably compact
spaces hold under PFA(S)[S]. We also show the consistency without large
cardinals of "every locally compact, perfectly normal space is paracompact".


title: Quantum mechanics before the big bang in heterotic-M-theory

abstract:
  In this letter we investigate the role played by quantum mechanics before the
big-bang in heterotic-M-theory assuming an orbifold compactification of time.
As we will see particles are localized around a black hole but only in regions
where a constructive quantum interference takes place. We infer that the
creation of this interference pattern is interesting for many reasons: (A) it
is a mechanism to localize particles on $S^4$ branes; (B) the Casimir potential
for the dilaton can be interpreted as a gravitational effective potential for a
two-body problem; (C) the quantum interference is a new way to define the
branes in heterotic-M-theory. Remarkably, a modified Schroedinger equation is
obtained. The stabilization of the branes' position is related to the absence
of a cosmological singularity.


title: PFA(S)[S] for the masses

abstract:
  We present S. Todorcevic's method of forcing with a coherent Souslin tree
over restricted iteration axioms as a black box usable by those who wish to
avoid its complexities but still access its power.


title:
Exact Lattice Supersymmetry at the Quantum Level for $N=2$ Wess-Zumino
  Models in 1- and 2-Dimensions

abstract:
  Supersymmetric lattice Ward-Takahashi identities are investigated
perturbatively up to two-loop corrections for super doubler approach of $N=2$
lattice Wess-Zumino models in 1- and 2-dimensions. In this approach notorious
chiral fermion doublers are treated as physical particles and momentum
conservation is modified in such a way that lattice Leibniz rule is satisfied.
The two major difficulties to keep exact lattice supersymmetry are overcome.
This formulation defines, however, nonlocal field theory. Nevertheless we
confirm that exact supersymmetry on the lattice is realized for all
supercharges at the quantum level. Delicate issues of associativity are also
discussed.


title: Rate Matrix Estimation From Site Frequency Data

abstract:
  A procedure is described for estimating evolutionary rate matrices from
observed site frequency data. The procedure assumes (1) that the data are
obtained from a constant size population evolving according to a stationary
Wright-Fisher model; (2) that the data consist of a multiple alignment of a
moderate number of sequenced genomes drawn randomly from the population; and
(3) that within the genome a large number of independent, neutral sites
evolving with with a common mutation rate matrix can be identified. No
restrictions are imposed on the scaled rate matrix other than that the
off-diagonal elements are positive and <<1, and that the rows sum to zero. In
particular the rate matrix is not assumed to be reversible. The key to the
method is an approximate stationary solution to the forward Kolmogorov equation
for the multi-allele neutral Wright-Fisher model in the limit of low mutation
rates.


title:
Vista: A Visually, Socially, and Temporally-aware Model for Artistic
  Recommendation

abstract:
  Understanding users' interactions with highly subjective content---like
artistic images---is challenging due to the complex semantics that guide our
preferences. On the one hand one has to overcome `standard' recommender systems
challenges, such as dealing with large, sparse, and long-tailed datasets. On
the other, several new challenges present themselves, such as the need to model
content in terms of its visual appearance, or even social dynamics, such as a
preference toward a particular artist that is independent of the art they
create.
  In this paper we build large-scale recommender systems to model the dynamics
of a vibrant digital art community, Behance, consisting of tens of millions of
interactions (clicks and `appreciates') of users toward digital art.
Methodologically, our main contributions are to model (a) rich content,
especially in terms of its visual appearance; (b) temporal dynamics, in terms
of how users prefer `visually consistent' content within and across sessions;
and (c) social dynamics, in terms of how users exhibit preferences both towards
certain art styles, as well as the artists themselves.


title:
Relationship between Granger non-causality and graph structure of
  state-space representations

abstract:
  In this paper we present an equivalent form of Granger noncausality in state
space representation. As a generalization of this result, necessary and
sufficient conditions are provided for an output process to admit a particular
minimal coordinated state space representation.


title: Representation of functions on big data associated with directed graphs

abstract:
  This paper is an extension of the previous work of Chui, Filbir, and Mhaskar
(Appl. Comput. Harm. Anal. 38 (3) 2015:489-509), not only from numeric data to
include non-numeric data as in that paper, but also from undirected graphs to
directed graphs (called digraphs, for simplicity). Besides theoretical
development, this paper introduces effective mathematical tools in terms of
certain data-dependent orthogonal systems for function representation and
analysis directly on the digraphs. In addition, this paper also includes
algorithmic development and discussion of various experimental results on such
data-sets as CORA, Proposition, and Wiki-votes.


title: Intrinsically Motivated Multimodal Structure Learning

abstract:
  We present a long-term intrinsically motivated structure learning method for
modeling transition dynamics during controlled interactions between a robot and
semi-permanent structures in the world. In particular, we discuss how
partially-observable state is represented using distributions over a Markovian
state and build models of objects that predict how state distributions change
in response to interactions with such objects. These structures serve as the
basis for a number of possible future tasks defined as Markov Decision
Processes (MDPs). The approach is an example of a structure learning technique
applied to a multimodal affordance representation that yields a population of
forward models for use in planning. We evaluate the approach using experiments
on a bimanual mobile manipulator (uBot-6) that show the performance of model
acquisition as the number of transition actions increases.


title:
On the stability of Einstein static universe at background level in
  massive bigravity

abstract:
  We study the static cosmological solutions and their stability at background
level in the framework of massive bigravity theory with
Friedmann-Robertson-Walker (FRW) metrics. By the modification proposed in the
cosmological equations subject to a perfect fluid we obtain new solutions
interpreted as the Einstein static universe. It turns out that the
non-vanishing size of initial scale factor of Einstein static universe depends
on the non-vanishing three-dimensional spatial curvature of FRW metrics and
also the graviton's mass. By dynamical system approach and numerical analysis,
we find that the extracted solutions for closed and open universes can be
stable for some viable ranges of equation of state parameter, viable values of
fraction of two scale factors, and viable values of graviton's mass obeying the
hierarchy $m << M_Pl$ which is more cosmologically motivated.


title:
DCAR: A Discriminative and Compact Audio Representation to Improve Event
  Detection

abstract:
  This paper presents a novel two-phase method for audio representation,
Discriminative and Compact Audio Representation (DCAR), and evaluates its
performance at detecting events in consumer-produced videos. In the first phase
of DCAR, each audio track is modeled using a Gaussian mixture model (GMM) that
includes several components to capture the variability within that track. The
second phase takes into account both global structure and local structure. In
this phase, the components are rendered more discriminative and compact by
formulating an optimization problem on Grassmannian manifolds, which we found
represents the structure of audio effectively.
  Our experiments used the YLI-MED dataset (an open TRECVID-style video corpus
based on YFCC100M), which includes ten events. The results show that the
proposed DCAR representation consistently outperforms state-of-the-art audio
representations. DCAR's advantage over i-vector, mv-vector, and GMM
representations is significant for both easier and harder discrimination tasks.
We discuss how these performance differences across easy and hard cases follow
from how each type of model leverages (or doesn't leverage) the intrinsic
structure of the data. Furthermore, DCAR shows a particularly notable accuracy
advantage on events where humans have more difficulty classifying the videos,
i.e., events with lower mean annotator confidence.


title:
DeepQA: Improving the estimation of single protein model quality with
  deep belief networks

abstract:
  Protein quality assessment (QA) by ranking and selecting protein models has
long been viewed as one of the major challenges for protein tertiary structure
prediction. Especially, estimating the quality of a single protein model, which
is important for selecting a few good models out of a large model pool
consisting of mostly low-quality models, is still a largely unsolved problem.
We introduce a novel single-model quality assessment method DeepQA based on
deep belief network that utilizes a number of selected features describing the
quality of a model from different perspectives, such as energy, physio-chemical
characteristics, and structural information. The deep belief network is trained
on several large datasets consisting of models from the Critical Assessment of
Protein Structure Prediction (CASP) experiments, several publicly available
datasets, and models generated by our in-house ab initio method. Our experiment
demonstrate that deep belief network has better performance compared to Support
Vector Machines and Neural Networks on the protein model quality assessment
problem, and our method DeepQA achieves the state-of-the-art performance on
CASP11 dataset. It also outperformed two well-established methods in selecting
good outlier models from a large set of models of mostly low quality generated
by ab initio modeling methods. DeepQA is a useful tool for protein single model
quality assessment and protein structure prediction. The source code,
executable, document and training/test datasets of DeepQA for Linux is freely
available to non-commercial users at http://cactus.rnet.missouri.edu/DeepQA/.


title: Single-photon stimulated four wave mixing at telecom band

abstract:
  Single-photon stimulated four wave mixing (StFWM) processes have great
potential for photonic quantum information processing, compatible with optical
communication technologies and integrated optoelectronics. In this paper, we
demonstrate single-photon StFWM process in a piece of optical fiber, with
seeded photons generated by spontaneous four wave mixing process (SpFWM). The
effect of the single-photon StFWM is confirmed by time-resolved four-photon
coincidence measurement and variation of four-photon coincidence counts under
different seed-pump delays. According to the experiment results, the potential
performance of quantum cloning machine based on the process is analyzed.


title: DSD: Dense-Sparse-Dense Training for Deep Neural Networks

abstract:
  Modern deep neural networks have a large number of parameters, making them
very hard to train. We propose DSD, a dense-sparse-dense training flow, for
regularizing deep neural networks and achieving better optimization
performance. In the first D (Dense) step, we train a dense network to learn
connection weights and importance. In the S (Sparse) step, we regularize the
network by pruning the unimportant connections with small weights and
retraining the network given the sparsity constraint. In the final D (re-Dense)
step, we increase the model capacity by removing the sparsity constraint,
re-initialize the pruned parameters from zero and retrain the whole dense
network. Experiments show that DSD training can improve the performance for a
wide range of CNNs, RNNs and LSTMs on the tasks of image classification,
caption generation and speech recognition. On ImageNet, DSD improved the Top1
accuracy of GoogLeNet by 1.1%, VGG-16 by 4.3%, ResNet-18 by 1.2% and ResNet-50
by 1.1%, respectively. On the WSJ'93 dataset, DSD improved DeepSpeech and
DeepSpeech2 WER by 2.0% and 1.1%. On the Flickr-8K dataset, DSD improved the
NeuralTalk BLEU score by over 1.7. DSD is easy to use in practice: at training
time, DSD incurs only one extra hyper-parameter: the sparsity ratio in the S
step. At testing time, DSD doesn't change the network architecture or incur any
inference overhead. The consistent and significant performance gain of DSD
experiments shows the inadequacy of the current training methods for finding
the best local optimum, while DSD effectively achieves superior optimization
performance for finding a better solution. DSD models are available to download
at https://songhan.github.io/DSD.


title:
Quantum thermal transport through anharmonic systems: A self-consistent
  approach

abstract:
  We propose a feasible and effective approach to study quantum thermal
transport through anharmonic systems. The main idea is to obtain an {\it
effective} harmonic Hamiltonian for the anharmonic system by applying the
self-consistent phonon theory. Using the effective harmonic Hamiltonian we
study thermal transport within the framework of nonequilibrium Green's function
method using the celebrated Caroli formula. We corroborate our quantum
self-consistent approach using the quantum master equation that can deal with
anharmonicity exactly, but is limited to the weak system-bath coupling regime.
Finally, in order demonstrate its strength we apply the quantum self-consistent
approach to study thermal rectification in a weakly coupled two segment
anharmonic system.


title: Emergent cosmic space in Rastall theory

abstract:
  Padmanabhan's emergent cosmic space proposal is employed to study the Rastall
theory which involves modifying the conservation law of energy-momentum tensor.
As a necessary element for this approach, we firstly propose a modified Komar
energy which reflects the evolution of the energy-momentum itself in the case
of a perfect fluid. After that, an expansion law is invoked to reobtain the
Friedmann equation in this theory.


title:
The Derivative of Influence Function, Location Breakdown Point, Group
  Leverage and Regression Residuals' Plots

abstract:
  In several linear regression data sets, $Y (\in R)$ on ${\bf X} (\in R^p),$
visual comparisons of $L_1$ and $L_2$-residuals' plots indicate bad leverage
cases. The phenomenon is confirmed theoretically by introducing Location
Breakdown Point (LBP) of a functional $T$: any point where the derivative of
$T$'s Influence Function either takes values at infinities or does not exist.
Guidelines for the plots' visual comparisons as diagnostic are provided. The
new tools used include E-matrix and suggest influence diagnostic RINFIN which
measures the distance in the derivatives of $L_2$-residuals} at $({\bf x},y)$
from model $F$ and from gross-error model $F_{\epsilon, {\bf x},y}.$ The larger
RINFIN$({\bf x},y)$ is, the larger $({\bf x},y)$'s influence in
$L_2$-regression residual is. RINFIN allows measuring group influence of $k$
${\bf x}$-neighboring data cases in a size $n$ sample using their average,
$(\bar {\bf x}_k,\bar y_k),$ as one case with weight $\epsilon=k/n.$ For high
dimensional, simulated data, the misclassification proportion of bad leverage
cases in data's RINFIN-ordering decreases to zero as $p$ increases, thus
reconfirming the blessing of high dimensionality in the detection of remote
clusters. The visual diagnostic and RINFIN are successful in applications and
complement each other.


title: Sulfur and zinc abundances of red giant stars

abstract:
  Sulfur and zinc are chemically volatile elements, which play significant
roles as depletion-free tracers in studying galactic chemical evolution.
However, regarding red giants having evolved off the main sequence, reliable
abundance determinations of S and Zn seem to be difficult despite that a few
studies have been reported so far. Given this situation, we tried to establish
the abundances of these elements for an extensive sample of 239 field GK giants
(-0.8 < [Fe/H] < +0.2), by applying the spectrum-fitting technique to S I
8694-5, S I 6757, and Zn I 6362 lines and by taking into account the non-LTE
effect. Besides, similar abundance analysis was done for 160 FGK dwarfs to be
used for comparison. The non-LTE corrections for the S and Zn abundances
derived from these lines turned out < 0.1(-0.2) dex for most cases and not very
significant. It revealed that the S I 6757 feature is more reliable as an
abundance indicator than S I 8694-5 for the case of red giants, because the
latter suffers blending of unidentified lines. The finally resulting
[S/Fe]-[Fe/H] and [Zn/Fe]-[Fe/H] relations for GK giants were confirmed to be
in good agreement with those for FGK dwarfs, indicating that S and Zn
abundances of red giants are reliably determinable from the S I 6757 and Zn I
6362 lines. Accordingly, not only main-sequence stars but also evolved red
giant stars are usable for tracing the chemical evolution history of S and Zn
in the regime of disk metallicity by using these lines.


title:
An analysis of spatiotemporal localized solutions in the variable
  coefficients (3+1)-dimensional nonlinear Schr\"{o}dinger equation with six
  different forms of dispersion parameters

abstract:
  We construct spatiotemporal localized envelope solutions of a
(3+1)-dimensional nonlinear Schr\"{o}dinger equation with varying coefficients
such as dispersion, nonlinearity and gain parameters through similarity
transformation technique. The obtained localized rational solutions can serve
as prototypes of rogue waves in different branches of science. We investigate
the characteristics of constructed localized solutions in detail when it
propagates through six different dispersion profiles, namely constant, linear,
Gaussian, hyperbolic, logarithm and exponential. We also obtain expressions for
the hump and valleys of rogue wave intensity profiles for these six dispersion
profiles and study the trajectory of it in each case. Further, we analyze how
the intensity of another localized solution, namely breather, changes when it
propagates through the aforementioned six dispersion profiles. Our studies
reveal that these localized solutions co-exist with the collapsing solutions
which are already found in the (3+1)-dimensional nonlinear Schr\"{o}dinger
equation. The obtained results will help to understand the corresponding
localized wave phenomena in related fields.


title:
Disintegrated order one differential equations and algebraic general
  solutions

abstract:
  We generalize results of Rosenlicht to give a necessary and sufficient
condition for when order one differential equations of the form $D(x) = f(x)$
where $f$ is a rational function is orthogonal to the constants. Following the
main results of the paper, we also explain the connection between algebraic
general solutions and weak orthogonality to the constants; a portion of this
discussion is given in the appendix, written jointly with Joel Nagloo and Ngoc
Thieu Vo.


title: Brownian duet: A novel tale of thermodynamic efficiency

abstract:
  We calculate analytically the stochastic thermodynamic properties of an
isothermal Brownian engine driven by a duo of time-periodic forces, including
its Onsager coefficients, the stochastic work of each force, and the
corresponding stochastic entropy production. We verify the relations between
different operational regimes, maximum power, maximum efficiency and minimum
dissipation, and reproduce the signature features of the stochastic efficiency.
All these results are experimentally tested without adjustable parameters on a
colloidal system.


title: Irreducible Integrable Representations of Toroidal Lie Algebras

abstract:
  The irreducible integrable representations with finite-dimensional weight
spaces of toroidal Lie algebras on which the center acts non-trivially were
classified by S.Eswara Rao. In this paper we give a compact proof of the
results that lead to the classification theorem. Further we establish a
necessary and sufficient condition under which two such irreducible modules are
isomorphic.


title:
Fractional powers of the wave operator via Dirichlet-to-Neumann maps in
  anti-de Sitter spaces

abstract:
  We show that the fractional wave operator, which is usually studied in the
context of hypersingular integrals but had not yet appeared in mathematical
physics, can be constructed as the Dirichlet-to-Neumann map associated with the
Klein-Gordon equation in anti-de Sitter spacetimes. Several generalizations of
this relation will be discussed too.


title:
Topological Dirac semimetal phases in InSb/$\alpha$-Sn semiconductor
  superlattices

abstract:
  We demonstrate theoretically the coexistence of Dirac semimetal and
topological insulator phases in InSb/$\alpha$-Sn conventional semiconductor
superlattices, based on advanced first-principles calculations combined with
low-energy $k\cdot p$ theory. By proper interfaces designing, a large interface
polarization emerges when the growth direction is chosen along {[}111{]}. Such
an intrinsic polarized electrostatic field reduces band gap largely and invert
the band structure finally, leading to emerge of the topological Dirac
semimetal phase with a pair of Dirac nodes appearing along the (111)
crystallographic direction near the $\Gamma$ point. The surface states and
Fermi arc are clearly observed in (100) projected surface. In addition, we also
find a two-dimensional topological insulator phase with large nontrivial band
gap approaching 70 meV, which make it possible to observe the quantum spin Hall
effect at room temperature. Our proposal paves a way to realize topological
nontrivial phases coexisted in conventional semiconductor superlattices by
proper interface designing.


title:
Spectral Characters of a class of Integrable Representations of Toroidal
  Lie Algebras

abstract:
  In this paper we study the subcategory of finite-length objects of the
category of positive level integrable representations of a toroidal Lie
algebra. The main goal is to characterize the blocks of the category. In the
cases when the underlying finite type Lie algebra associated with the toroidal
Lie algebra is simply-laced, we are able to give a parametrization for the
blocks.


title:
Equivalent circuit representation of hysteresis in solar cells that
  considers interface charge accumulation: Potential cause of hysteresis in
  perovskite solar cells

abstract:
  If charge carriers accumulate in the charge transport layer of a solar cell,
then the transient response of the electric field that originates from these
accumulated charges results in hysteresis in the current-voltage ($J$-$V$)
characteristics. While this mechanism was previously known, a theoretical model
to explain these $J$-$V$ characteristics has not been considered to date. We
derived an equivalent circuit from the proposed hysteresis mechanism. By
solving the equivalent circuit model, we were able to reproduce some of the
features of hysteresis in perovskite solar cells.


title:
Berezin transform and Toeplitz operators on weighted Bergman spaces
  induced by regular weights

abstract:
  Given a regular weight $\omega$ and a positive Borel measure $\mu$ on the
unit disc $\mathbb{D}$, the Toeplitz operator associated with $\mu$ is
  $$
  \mathcal{T}_\mu(f)(z)=\int_{\mathbb{D}}
f(\zeta)\bar{B_z^\omega(\zeta)}\,d\mu(\zeta),
  $$ where $B^\omega_{z}$ are the reproducing kernels of the weighted Bergman
space $A^2_\omega$. We describe bounded and compact Toeplitz operators
$\mathcal{T}_\mu:A^p_\omega\to A^q_\omega$, $1<q,p<\infty$, in terms of
Carleson measures and the Berezin transform
  $$
  \widetilde{\mathcal{T}_\mu}(z)=\frac{\langle\mathcal{T}_\mu(B^\omega_{z}),
B^\omega_{z} \rangle_{A^2_\omega}}{\|B_z^\omega\|^2_{A^2_\omega}}.
  $$ We also characterize Schatten class Toeplitz operators in terms of the
Berezin transform and apply this result to study Schatten class composition
operators.


title:
Lotka-Volterra with randomly fluctuating environments: a full
  description

abstract:
  In this note, we study the long time behavior of Lotka-Volterra systems whose
coefficients vary randomly. Benam and Lobry established that randomly switching
between two environments that are both favorable to the same species may lead
to four different regimes: almost sure extinction of one of the two species,
random extinction of one species or the other and persistence of both species.
Our purpose here is to provide a complete description of the model. In
particular, we show that any couple of environments may lead to the four
different behaviours of the stochastic process depending on the jump rates.


title: Spontaneous symmetry breaking in 5D conformally invariant gravity

abstract:
  We explore the possibility of the spontaneous symmetry breaking in 5D
conformally invariant gravity, whose action consists of a scalar field
nonminimally coupled to the curvature with its potential. Performing
dimensional reduction via ADM decomposition, we find that the model allows an
exact solution giving rise to the 4D Minkowski vacuum. Exploiting the conformal
invariance with Gaussian warp factor, we show that it also admits a solution
which implement the spontaneous breaking of conformal symmetry. We investigate
its stability by performing the tensor perturbation and find the resulting
system is described by the conformal quantum mechanics. Possible applications
to the spontaneous symmetry breaking of time-translational symmetry along the
dynamical fifth direction and the brane-world scenario are discussed.


title:
Global well-posedness of the MHD equations in a homogeneous magnetic
  field

abstract:
  In this paper, we study the MHD equations with small viscosity and
resistivity coefficients, which may be different. This is a typical setting in
high temperature plasmas. It was proved that the MHD equations are globally
well-posed if the initial velocity is close to 0 and the initial magnetic field
is close to a homogeneous magnetic field in the weighted H\"{o}lder space,
where the closeness is independent of the dissipation coefficients.


title: Carbon-oxygen-neon mass nuclei in superstrong magnetic fields

abstract:
  The properties of $\isotope[12]{C}$, $\isotope[16]{O}$, and
$\isotope[20]{Ne}$ nuclei in strong magnetic fields $B\simeq 10^{17}\,$G are
studied in the context of strongly magnetized neutron stars and white dwarfs.
The SKY3D code is extended to incorporate the interaction of nucleons with the
magnetic field and is utilized to solve the time-independent Hartree-Fock
equations with a Skyrme interaction on a Cartesian three-dimensional grid. The
numerical solutions demonstrate a number of phenomena, which include a
splitting of the energy levels of spin-up and -down nucleons, spontaneous
rearrangment of energy levels in $\isotope[16]{O}$ at a critical field, which
leads to jump-like increases of magnetization and proton current in this
nucleus, and evolution of the intrinsically deformed $\isotope[20]{Ne}$ nucleus
towards a more spherical shape under increasing field strength. Many of the
numerical features can be understood within a simple analytical model based on
the occupation by the nucleons of the lowest states of the harmonic oscillator
in a magnetic field.


title: Intrinsic origin of electron scattering at 4H-SiC(0001)/SiO$_2$

abstract:
  We introduce a first-principles study to clarify the carrier-scattering
property at the SiC/SiO$_2$. Interestingly, the electron transport at the
conduction-band edge is significantly affected by the introduction of oxygen,
even though there are no electrically active defects. The origin of the large
scattering is explained by the behavior of the internal-space states (ISSs).
Moreover, the effect of the ISSs is larger than that of the electrically active
carbon-related defects. This result indicates that an additional scattering not
considered in a conventional Si/SiO$_2$ occurs at the SiC/SiO$_2$.


title: Consciousness and quantum mechanics of macroscopic systems

abstract:
  We propose the quantum mechanical description of complex systems should be
performed using two types of causality relation: the ordering relation ($x\prec
y$) and the subset relation ($A\subseteq B$). The structures with two ordering
operations, called the causal sites, have been already proposed in context of
quantum gravity (Christensen and Crane, 2005). We suggest they are also common
to biological physics and may describe how the brain works. In the spirit of
the Penrose ideas we identify the geometry of the space-time with universal
field of consciousness. The latter has its evident counterparts in ancient
Indian philosophy and provides a framework for unification of physical and
mental phenomena.


title:
Geodesic ball packings generated by regular prism tilings in
  $\mathbf{Nil}$ geometry

abstract:
  In this paper we study the regular prism tilings and construct ball packings
by geodesic balls related to the above tilings in the projective model of
$\mathbf{Nil}$ geometry. Packings are generated by action of the discrete prism
groups $\mathbf{pq2_{1}}$. We prove that these groups are realized by prism
tilings in $\mathbf{Nil}$ space if $(p,q)=(3,6), (4,4), (6,3)$ and determine
packing density formulae for geodesic ball packings generated by the above
prism groups. Moreover, studying these formulae we determine the conjectured
maximal dense packing arrangements and their densities and visualize them in
the projective model of $\mathbf{Nil}$ geometry. We get a dense (conjectured
locally densest) geodesic ball arrangement related to the parameters
$(p,q)=(6,3)$ where the kissing number of the packing is $14$, similarly to the
densest lattice-like $\mathbf{Nil}$ geodesic ball arrangement investigated by
the second author .


title:
Far-infrared and dust properties of present-day galaxies in the EAGLE
  simulations

abstract:
  The EAGLE cosmological simulations reproduce the observed galaxy stellar mass
function and many galaxy properties. In this work, we study the dust-related
properties of present-day EAGLE galaxies through mock observations in the
far-infrared and submm wavelength ranges obtained with the 3D dust radiative
transfer code SKIRT. To prepare an EAGLE galaxy for radiative transfer
processing, we derive a diffuse dust distribution from the gas particles and we
re-sample the star-forming gas particles and the youngest star particles into
star-forming regions that are assigned dedicated emission templates. We select
a set of redshift-zero EAGLE galaxies that matches the K-band luminosity
distribution of the galaxies in the Herschel Reference Survey (HRS), a
volume-limited sample of about 300 normal galaxies in the Local Universe. We
find overall agreement of the EAGLE dust scaling relations with those observed
in the HRS, such as the dust-to-stellar mass ratio versus stellar mass and
versus NUV-r colour relations. A discrepancy in the f_250/f_350 versus
f_350/f_500 submm colour-colour relation implies that part of the simulated
dust is insufficiently heated, likely because of limitations in our sub-grid
model for star-forming regions. We also investigate the effect of adjusting the
metal-to-dust ratio and the covering factor of the photodissociation regions
surrounding the star-forming cores. We are able to constrain the important
dust-related parameters in our method, informing the calculation of dust
attenuation for EAGLE galaxies in the UV and optical domain.


title: Heuristics for Packing Semifluids

abstract:
  Physical properties of materials are seldom studied in the context of packing
problems. In this work we study the behavior of semifluids: materials with
particular characteristics, that share properties both with solids and with
fluids. We describe the importance of some specific semifluids in an industrial
context, and propose methods for tackling the problem of packing them, taking
into account several practical requirements and physical constraints. Although
the focus of this paper is on the computation of practical solutions, it also
uncovers interesting mathematical properties of this problem, which
differentiate it from other packing problems.


title:
Automated Fourier space region-recognition filtering for off-axis
  digital holographic microscopy

abstract:
  Automated label-free quantitative imaging of biological samples can greatly
benefit high throughput diseases diagnosis. Digital holographic microscopy
(DHM) is a powerful quantitative label-free imaging tool that retrieves
structural details of cellular samples non-invasively. In off-axis DHM, a
proper spatial filtering window in Fourier space is crucial to the quality of
reconstructed phase image. Here we describe a region-recognition approach that
combines shape recognition with an iterative thresholding to extracts the
optimal shape of frequency components. The region recognition technique offers
fully automated adaptive filtering that can operate with a variety of samples
and imaging conditions. When imaging through optically scattering biological
hydrogel matrix, the technique surpasses previous histogram thresholding
techniques without requiring any manual intervention. Finally, we automate the
extraction of the statistical difference of optical height between malaria
parasite infected and uninfected red blood cells. The method described here
pave way to greater autonomy in automated DHM imaging for imaging live cell in
thick cell cultures.


title: Dissecting nucleon transition electromagnetic form factors

abstract:
  In Poincar\'e-covariant continuum treatments of the three valence-quark
bound-state problem, the force behind dynamical chiral symmetry breaking also
generates nonpointlike, interacting diquark correlations in the nucleon and its
resonances. We detail the impact of these correlations on the
electromagnetically-induced nucleon-$\Delta$ and nucleon-Roper transitions,
providing a flavour-separation of the latter and associated predictions that
can be tested at modern facilities.


title:
Tunable mechanical coupling between driven microelectromechanical
  resonators

abstract:
  We present a microelectromechanical system, in which a silicon beam is
attached to a comb-drive actuator, that is used to tune the tension in the
silicon beam, and thus its resonance frequency. By measuring the resonance
frequencies of the system, we show that the comb-drive actuator and the silicon
beam behave as two strongly coupled resonators. Interestingly, the effective
coupling rate (~ 1.5 MHz) is tunable with the comb-drive actuator (+10%) as
well as with a side-gate (-10%) placed close to the silicon beam. In contrast,
the effective spring constant of the system is insensitive to either of them
and changes only by $\pm$ 0.5%. Finally, we show that the comb-drive actuator
can be used to switch between different coupling rates with a frequency of at
least 10 kHz.


title:
Non-area-specific adjustment factor for second-order efficient empirical
  Bayes confidence interval

abstract:
  An empirical Bayes confidence interval has high user demand in many
applications. In particular, the second-order empirical Bayes confidence
interval, the coverage error of which is of the third order for large number of
areas, is widely used in small area estimation when the sample size within each
area is not large enough to make reliable direct estimates based on a
design-based approach. Yoshimori and Lahiri (2014a) proposed a new type of
confidence interval, called the second-order efficient empirical Bayes
confidence interval, whose length is less than that of the direct confidence
interval based on the design-based approach. However, this interval still has
some disadvantages: (i) it is hard to use when at least one leverage value is
high; (ii) many iterations tend to be required to obtain the estimators of one
global model variance parameter as the number of areas getting larger, due to
the area-specific adjustment factor. To prevent such issues, this paper
proposes, as never done before, a more efficient confidence interval to allow
for high leverage and reduce the number of iterations for large number of
areas, by adopting a non-area-specific adjustment factor, maintaining the
existing desired properties. We also reveal the relationship between the
general adjustment factor and the measure of uncertainty of the empirical Bayes
estimator to create a second-order confidence interval. Moreover, we present
two simulation studies and a real data analysis to show the efficiency of this
confidence interval.


title:
Kinetic Monte Carlo Simulation of Single-Electron Multiple-Trapping
  Transport in Disordered Media

abstract:
  The conventional single-particle Monte Carlo simulation of charge transport
in disordered media is based on the truncated density of localized states
(DOLS) which benefits from very short time execution. Although this model
successfully clarifies the properties of electron transport in moderately
disordered media, it overestimates the electron diffusion coefficient for
strongly disordered media. The origin of this deviation is discussed in terms
of zero-temperature approximation in the truncated DOLS and the ignorance of
spatial occupation of localized states. Here, based on the multiple-trapping
regime we introduce a modified single-particle kinetic Monte Carlo model that
can be used to investigate the electron transport in any disordered media
independent from the value of disorder parameter. In the proposed model,
instead of using a truncated DOLS we imply the raw DOLS. In addition, we have
introduced an occupation index for localized states to consider the effect of
spatial occupation of trap sites. The proposed model is justified in a simple
cubic lattice of trap sites for broad interval of disorder parameters, Fermi
levels, and temperatures.


title:
Polarized proton-deuteron scattering as a test of time-reversal
  invariance

abstract:
  Scattering of protons with transversal polarization $p_y^p$ on deuterons with
tensor polarization $P_{xz}$ provides a null-test signal for time-reversal (T)
invariance violating but parity (P) conserving effects. We calculate the
corresponding null-test observable at beam energies 100-1000 MeV within the
spin-dependent Glauber theory considering T-violating P-conserving
nucleon-nucleon interactions. The S-wave component of the deuteron wave
function as well as the D-wave are taken into account and the latter is found
to play an important role for the magnitude and the energy dependence of the
observable in question. Specifically, with inclusion of the D wave the maximum
of the obtained signal is shifted to higher beam energies, i.e. to 700-800 MeV.


title:
Separating Pathways in Double-Quantum Optical Spectroscopy Reveals
  Excitonic Interactions

abstract:
  Techniques for coherent multidimensional optical spectroscopy have been
developed and utilised to understand many different processes, including energy
transfer in photosynthesis and many-body effects in semiconductor
nanostructures. Double-quantum 2D spectroscopy is one variation that has been
particularly useful for understanding many-body effects. In condensed matter
systems, however, there are often many competing signal pathways, which can
make it difficult to isolate different contributions and retrieve quantitative
information. Here, a means of separating overlapping pathways while maintaining
the fidelity of the relevant peak/s is demonstrated. This selective approach is
used to isolate the double-quantum signal from a mixed two exciton state in a
semiconductor quantum well. The removal of overlapping peaks allows analysis of
the relevant peak-shape and thus details of interactions with the environment
and other carriers to be revealed. An alternative pulse ordering identifies a
double-quantum state associated only with GaAs defects, the signature of which
has previously been confused with other interaction induced effects. The
experimental approach described here provides access to otherwise hidden
details of excitonic interactions and demonstrates that the manner in which the
double-quantum coherence is generated can be important and provide an
additional control to help understand the many-body physics in complex systems.


title:
Model-Driven Feed-Forward Prediction for Manipulation of Deformable
  Objects

abstract:
  Robotic manipulation of deformable objects is a difficult problem especially
because of the complexity of the many different ways an object can deform.
Searching such a high dimensional state space makes it difficult to recognize,
track, and manipulate deformable objects. In this paper, we introduce a
predictive, model-driven approach to address this challenge, using a
pre-computed, simulated database of deformable object models. Mesh models of
common deformable garments are simulated with the garments picked up in
multiple different poses under gravity, and stored in a database for fast and
efficient retrieval. To validate this approach, we developed a comprehensive
pipeline for manipulating clothing as in a typical laundry task. First, the
database is used for category and pose estimation for a garment in an arbitrary
position. A fully featured 3D model of the garment is constructed in real-time
and volumetric features are then used to obtain the most similar model in the
database to predict the object category and pose. Second, the database can
significantly benefit the manipulation of deformable objects via non-rigid
registration, providing accurate correspondences between the reconstructed
object model and the database models. Third, the accurate model simulation can
also be used to optimize the trajectories for manipulation of deformable
objects, such as the folding of garments. Extensive experimental results are
shown for the tasks above using a variety of different clothing.


title: High-precision astrometry towards ELTs

abstract:
  With the aim of paving the road for future accurate astrometry with MICADO at
the European-ELT, we performed an astrometric study using two different but
complementary approaches to investigate two critical components that contribute
to the total astrometric accuracy. First, we tested the predicted improvement
in the astrometric measurements with the use of an atmospheric dispersion
corrector (ADC) by simulating realistic images of a crowded Galactic globular
cluster. We found that the positional measurement accuracy should be improved
by up to ~2 mas with the ADC, making this component fundamental for
high-precision astrometry. Second, we analysed observations of a globular
cluster taken with the only currently available Multi-Conjugate Adaptive Optics
assisted camera, GeMS/GSAOI at Gemini South. Making use of previously measured
proper motions of stars in the field of view, we were able to model the
distortions affecting the stellar positions. We found that they can be as large
as ~200 mas, and that our best model corrects them to an accuracy of ~1 mas. We
conclude that future astrometric studies with MICADO requires both an ADC and
an accurate modelling of distortions to the field of view, either through an
a-priori calibration or an a-posteriori correction.


title: On quantum critical destruction of the pseudogap phase

abstract:
  Recent data on the critical events accompanying the quenching of the
pseudogap (PG) phase in hole-doped cuprates are analysed. An original multiband
model with the spectrum influenced by doping has been used. Two critical
dopings are expected in evolving of the PG to destruction. The first of them
corresponds to metallization (antinodal) of the sample. Extended doping leads
to a second critical point where the PG is lost. In between the restoration of
the full Fermi surface proceeds. Band overlaps besides the location of the
chemical potential ({\mu}) are decisive.


title: Spectral characteristics of a fully-superconducting SQUIPT

abstract:
  We consider properties of a fully superconducting variant of the
superconducting quantum interference proximity transistor magnetic flux sensor.
We study the density of states in a finite-size superconducting metal wire in
the diffusive limit, and how it depends on the phase gradient of the order
parameter. We describe the dependence on the junction length and interface
transparency, and discuss properties relevant for using the structure in
magnetic flux detection applications.


title:
A survey of luminous high-redshift quasars with SDSS and WISE II. the
  bright end of the quasar luminosity function at z ~ 5

abstract:
  This is the second paper in a series on a new luminous z ~ 5 quasar survey
using optical and near-infrared colors. Here we present a new determination of
the bright end of the quasar luminosity function (QLF) at z ~ 5. Combined our
45 new quasars with previously known quasars that satisfy our selections, we
construct the largest uniform luminous z ~ 5 quasar sample to date, with 99
quasars in the range 4.7 <= z < 5.4 and -29 < M1450 <= -26.8, within the Sloan
Digital Sky Survey (SDSS) footprint. We use a modified 1/Va method including
flux limit correction to derive a binned QLF, and we model the parametric QLF
using maximum likelihood estimation. With the faint-end slope of the QLF fixed
as alpha = -2.03 from previous deeper samples, the best fit of our QLF gives a
flatter bright end slope beta = -3.58+/-0.24 and a fainter break magnitude
M*1450 = -26.98+/-0.23 than previous studies at similar redshift. Combined with
previous work at lower and higher redshifts, our result is consistent with a
luminosity evolution and density evolution (LEDE) model. Using the best fit
QLF, the contribution of quasars to the ionizing background at z ~ 5 is found
to be 18% - 45% with a clumping factor C of 2 - 5. Our sample suggests an
evolution of radio loud fraction with optical luminosity but no obvious
evolution with redshift.


title:
Normal modes of a superconducting transmission-line resonator with
  embedded lumped element circuit components

abstract:
  We present a method to identify the coupled, normal modes of a
superconducting transmission-line with an embedded lumped element circuit. We
evaluate the effective transmission-line non-linearities in the case of
Kerr-like Josephson interactions in the circuit and in the case where the
embedded circuit constitutes a qubit degree of freedom, which is Rabi coupled
to the field in the transmission-line. Our theory quantitatively accounts for
the very high and positive Kerr non-linearities observed in a recent experiment
[M. Reh\'ak et.al., Appl. Phys. Lett. 104, 162604], and we can evaluate the
accomplishments of modified versions of the experimental circuit.


title: Time-dependent correlations in quantum magnets at finite temperature

abstract:
  In this article we investigate the time dependence of the gap mode of copper
nitrate at various temperatures. We combine state-of-the-art theoretical
calculations with high precision neutron resonance spin-echo measurements to
understand the anomalous decoherence effects found previously in this material.
It is shown that the time domain offers a complementary view on this
phenomenon, which allows us to directly compare experimental data and
theoretical predictions without the need of further intensive data analysis,
such as (de)convolution.


title:
Studying generalised dark matter interactions with extended
  halo-independent methods

abstract:
  The interpretation of dark matter direct detection experiments is complicated
by the fact that neither the astrophysical distribution of dark matter nor the
properties of its particle physics interactions with nuclei are known in
detail. To address both of these issues in a very general way we develop a new
framework that combines the full formalism of non-relativistic effective
interactions with state-of-the-art halo-independent methods. This approach
makes it possible to analyse direct detection experiments for arbitrary dark
matter interactions and quantify the goodness-of-fit independent of
astrophysical uncertainties. We employ this method in order to demonstrate that
the degeneracy between astrophysical uncertainties and particle physics
unknowns is not complete. Certain models can be distinguished in a
halo-independent way using a single ton-scale experiment based on liquid xenon,
while other models are indistinguishable with a single experiment but can be
separated using combined information from several target elements.


title: L\'evy statistics of interacting Rydberg gases

abstract:
  A statistical analysis of the laser excitation of cold and randomly
distributed atoms to Rydberg states is developed. We first demonstrate with a
hard ball model that the distribution of energy level shifts in an interacting
gas obeys L\'evy statistics, in any dimension $d$ and for any interaction
$-C_p/R^p$ under the condition $d/p<1$. This result is confirmed with a Monte
Carlo rate equations simulation of the actual laser excitation in the
particular case $p=6$ and $d=3$. With this finding, we develop a statistical
approach for the modeling of probe light transmission through a cold atom gas
driven under conditions of electromagnetically induced transparency involving a
Rydberg state. The simulated results are in good agreement with experiment.


title: Modeling the Evolution of Line-of-Sight Blockage for V2V Channels

abstract:
  We investigate the evolution of line of sight (LOS) blockage over both time
and space for vehicle-to-vehicle (V2V) channels. Using realistic vehicular
mobility and building and foliage locations from maps, we first perform LOS
blockage analysis to extract LOS probabilities in real cities and on highways
for varying vehicular densities. Next, to model the time evolution of LOS
blockage for V2V links, we employ a three-state discrete-time Markov chain
comprised of the following states: i) LOS; ii) non-LOS due to static objects
(e.g., buildings, trees, etc.); and iii) non-LOS due to mobile objects
(vehicles). We obtain state transition probabilities based on the evolution of
LOS blockage. Finally, we perform curve fitting and obtain a set of
distance-dependent equations for both LOS and transition probabilities. These
equations can be used to generate time-evolved V2V channel realizations for
representative urban and highway environments. Our results can be used to
perform highly efficient and accurate simulations without the need to employ
complex geometry-based models for link evolution.


title: Password Generators: Old Ideas and New

abstract:
  This paper considers password generators, i.e. systems designed to generate
site-specific passwords on demand. Such systems are an alternative to password
managers. Over the last 15 years a range of password generator systems have
been described. This paper proposes the first general model for such systems,
and critically examines options for instantiating this model; options
considered include all those previously proposed as part of existing schemes as
well as certain novel possibilities. The model enables a more objective and
high-level assessment of the design of such systems; it has also been used to
sketch a possible new scheme, AutoPass, intended to incorporate the best
features of the prior art whilst also addressing many of the most serious
shortcomings of existing systems through the inclusion of novel features.


title: Holographic Corrections to the Veneziano Amplitude

abstract:
  We propose a holographic computation of the $2\rightarrow 2$ meson scattering
in a curved string background, dual to a QCD-like theory. We recover the
Veneziano amplitude and compute a perturbative correction due to the background
curvature. The result implies a small deviation from a linear trajectory, which
is a requirement of the UV regime of QCD.


title: Attention-over-Attention Neural Networks for Reading Comprehension

abstract:
  Cloze-style queries are representative problems in reading comprehension.
Over the past few months, we have seen much progress that utilizing neural
network approach to solve Cloze-style questions. In this paper, we present a
novel model called attention-over-attention reader for the Cloze-style reading
comprehension task. Our model aims to place another attention mechanism over
the document-level attention, and induces "attended attention" for final
predictions. Unlike the previous works, our neural network model requires less
pre-defined hyper-parameters and uses an elegant architecture for modeling.
Experimental results show that the proposed attention-over-attention model
significantly outperforms various state-of-the-art systems by a large margin in
public datasets, such as CNN and Children's Book Test datasets.


title:
Investigations of the effects of random sampling patterns on the
  stability of generalized sampling

abstract:
  We investigate how the choice of spatial point process for generating random
sampling patterns affects the numerical stability of non-uniform generalized
sampling between Fourier bases and Daubechies scaling functions. Specifically,
we consider binomial, Poisson and determinantal point processes and demonstrate
that the more regular point patterns from the determinantal point process are
superior.


title: Algebras whose right nucleus is a central simple algebra

abstract:
  We generalize Amitsur's construction of central simple algebras over a field
$F$ which are split by field extensions possessing a derivation with field of
constants $F$ to nonassociative algebras: for every central division algebra
$D$ over a field $F$ of characteristic zero there exists an
infinite-dimensional unital nonassociative algebra whose right nucleus is $D$
and whose left and middle nucleus are a field extension $K$ of $F$ splitting
$D$, where $F$ is algebraically closed in $K$. We then give a short direct
proof that every $p$-algebra of degree $m$, which has a purely inseparable
splitting field $K$ of degree $m$ and exponent one, is a differential extension
of $K$ and cyclic. We obtain finite-dimensional division algebras over a field
$F$ of characteristic $p>0$ whose right nucleus is a division $p$-algebra.


title: New phase space calculations for beta-decay half-lives

abstract:
  We revisit the computation of the phase space factors (PSF) involved in the
positron decay and electron capture (EC) processes for a large number of nuclei
of experimental interest. To obtain the electron/positron wave functions needed
in computation, we develop a code for solving accurately the Dirac equation
with a nuclear potential derived from a realistic proton density distribution
in the nucleus. The finite nuclear size (FNS) and screening effects are
included through recipes which differ from those used in previous calculations.
Comparing our results with former calculations employing approximate methods
but computed with the same Q-values, we find a close agreement for positron
decays, while for the EC process there are relevant differences. For the EC
process we also find that the screening effect has a notable influence on the
computed PSF values specially for light nuclei. Further, we re-computed the
same PSF values but using the most recent Q-values reported in literature. In
several cases these new Q-values differ significantly from the older ones,
which results in large differences in the PSF values as compared with previous
results. These new PSF values proposed here, can contribute to a more reliable
calculation of the beta decay rates, which are key quantities in the study of
nuclei far from the stability line, as well as to better understanding of the
stellar evolution.


title:
A Theoretical Analysis of the BDeu Scores in Bayesian Network Structure
  Learning

abstract:
  In Bayesian network structure learning (BNSL), we need the prior probability
over structures and parameters. If the former is the uniform distribution, the
latter determines the correctness of BNSL. In this paper, we compare BDeu
(Bayesian Dirichlet equivalent uniform) and Jeffreys' prior w.r.t. their
consistency. When we seek a parent set $U$ of a variable $X$, we require
regularity that if $H(X|U)\leq H(X|U')$ and $U\subsetneq U'$, then $U$ should
be chosen rather than $U'$. We prove that the BDeu scores violate the property
and cause fatal situations in BNSL. This is because for the BDeu scores, for
any sample size $n$,there exists a probability in the form
$P(X,Y,Z)={P(XZ)P(YZ)}/{P(Z)}$ such that the probability of deciding that $X$
and $Y$ are not conditionally independent given $Z$ is more than a half. For
Jeffreys' prior, the false-positive probability uniformly converges to zero
without depending on any parameter values, and no such an inconvenience occurs.


title: On the Stability of a Full-Duplex Aloha Network

abstract:
  This letter offers the first characterisation of the stability for
full-duplex large size networks. Through stochastic geometry tools, key
performance metrics like delay and maximum stable arrival rate are derived for
the non saturated system and compared to a half-duplex counterpart, also
accounting for imperfect self-interference cancellation. This analysis better
identifies that the full-duplex advantage is prominent for sparse networks,
whereas in dense topologies residual self-interference may hinder achievable
gains.


title: Orthogonal trades in complete sets of MOLS

abstract:
  Let $B_p$ be the Latin square given by the addition table for the integers
modulo an odd prime $p$. Here we consider the properties of Latin trades in
$B_p$ which preserve orthogonality with one of the $p-1$ MOLS given by the
finite field construction. We show that for certain choices of the orthogonal
mate, there is a lower bound logarithmic in $p$ for the number of times each
symbol occurs in such a trade, with an overall lower bound of
$(\log{p})^2/\log\log{p}$ for the size of such a trade. Such trades imply the
existence of orthomorphisms of the cyclic group which differ from a linear
orthomorphism by a small amount. We also show that any transversal in $B_p$
hits the main diagonal either $p$ or at most $p-\log_2{p}-1$ times. Finally, if
$p\equiv 1\mod{6}$ we show the existence of Latin square containing a $2\times
2$ subsquare which is orthogonal to $B_p$.


title: The Empirical Beta Copula

abstract:
  Given a sample from a multivariate distribution $F$, the uniform random
variates generated independently and rearranged in the order specified by the
componentwise ranks of the original sample look like a sample from the copula
of $F$. This idea can be regarded as a variant on Baker's [J. Multivariate
Anal. 99 (2008) 2312--2327] copula construction and leads to the definition of
the empirical beta copula. The latter turns out to be a particular case of the
empirical Bernstein copula, the degrees of all Bernstein polynomials being
equal to the sample size.
  Necessary and sufficient conditions are given for a Bernstein polynomial to
be a copula. These imply that the empirical beta copula is a genuine copula.
Furthermore, the empirical process based on the empirical Bernstein copula is
shown to be asymptotically the same as the ordinary empirical copula process
under assumptions which are significantly weaker than those given in Janssen,
Swanepoel and Veraverbeke [J. Stat. Plan. Infer. 142 (2012) 1189--1197].
  A Monte Carlo simulation study shows that the empirical beta copula
outperforms the empirical copula and the empirical checkerboard copula in terms
of both bias and variance. Compared with the empirical Bernstein copula with
the smoothing rate suggested by Janssen et al., its finite-sample performance
is still significantly better in several cases, especially in terms of bias.


title: Edge-Orders

abstract:
  Canonical orderings and their relatives such as st-numberings have been used
as a key tool in algorithmic graph theory for the last decades. Recently, a
unifying concept behind all these orders has been shown: they can be described
by a graph decomposition into parts that have a prescribed vertex-connectivity.
  Despite extensive interest in canonical orderings, no analogue of this
unifying concept is known for edge-connectivity. In this paper, we establish
such a concept named edge-orders and show how to compute (1,1)-edge-orders of
2-edge-connected graphs as well as (2,1)-edge-orders of 3-edge-connected graphs
in linear time, respectively. While the former can be seen as the edge-variants
of st-numberings, the latter are the edge-variants of Mondshein sequences and
non-separating ear decompositions. The methods that we use for obtaining such
edge-orders differ considerably in almost all details from the ones used for
their vertex-counterparts, as different graph-theoretic constructions are used
in the inductive proof and standard reductions from edge- to
vertex-connectivity are bound to fail.
  As a first application, we consider the famous Edge-Independent Spanning Tree
Conjecture, which asserts that every k-edge-connected graph contains k rooted
spanning trees that are pairwise edge-independent. We illustrate the impact of
the above edge-orders by deducing algorithms that construct 2- and 3-edge
independent spanning trees of 2- and 3-edge-connected graphs, the latter of
which improves the best known running time from O(n^2) to linear time.


title:
Optically induced spin-dependent diffusive transport in the presence of
  spin-orbit interaction for all-optical magnetization reversal

abstract:
  We have considered the effect of different spin-orbit interaction mechanisms
on the process of demagnetization under the influence of short-pulse lasers.
All-optical magnetization reversal of perpendicularly magnetized thin films can
occur if there are sufficient strong spin-Hall, skew scattering, and Rashba
interactions. In the presence of spin-orbit interactions, the transient charge
currents provide the generation of transverse-spin currents and accumulations,
which eventually exert spin-transfer torque on the magnetization. By combining
the optically excited spin-dependent diffusive transport with the spin and
charge currents due to skew scattering, spin-Hall, inverse spin-Hall and Rashba
interactions, into a numerical model, we demonstrate a possibility of
ultra-fast all-optical magnetization reversal. This understanding provokes
intriguing, more in-depth experimental studies on the role of spin-orbit
interaction mechanisms in optimizing structures for all-optical magnetization
reversal.


title: End-to-End Learning for Image Burst Deblurring

abstract:
  We present a neural network model approach for multi-frame blind
deconvolution. The discriminative approach adopts and combines two recent
techniques for image deblurring into a single neural network architecture. Our
proposed hybrid-architecture combines the explicit prediction of a
deconvolution filter and non-trivial averaging of Fourier coefficients in the
frequency domain. In order to make full use of the information contained in all
images in one burst, the proposed network embeds smaller networks, which
explicitly allow the model to transfer information between images in early
layers. Our system is trained end-to-end using standard backpropagation on a
set of artificially generated training examples, enabling competitive
performance in multi-frame blind deconvolution, both with respect to quality
and runtime.


title:
Diffractive and non-diffractive wounded nucleons and final states in pA
  collisions

abstract:
  We review the state-of-the-art of Glauber-inspired models for estimating the
distribution of the number of participating nucleons in pA and AA collisions.
We argue that there is room for improvement in these models when it comes to
the treatment of diffractive excitation processes, and present a new simple
Glauber-like model where these processes are better taken into account. We also
suggest a new way of using the number of participating, or wounded, nucleons to
extrapolate event characteristics from pp collisions, and hence get an estimate
of basic hadronic final-state properties in pA collisions, which may be used to
extract possible nuclear effects. The new method is inspired by the Fritiof
model, but based on the full, semi-hard multiparton interaction model of Pythia
8.