title: Physical Layer Security for Massive MIMO Systems Impaired by Phase Noise

abstract:
  In this paper, we investigate the impact of phase noise on the secrecy
performance of downlink massive MIMO systems in the presence of a passive
multiple-antenna eavesdropper. Thereby, for the base station (BS) and the
legitimate users, the effect of multiplicative phase noise is taken into
account, whereas the eavesdropper is assumed to employ ideal hardware. We
derive a lower bound for the ergodic secrecy rate of a given user when matched
filter data precoding and artificial noise transmission are employed at the BS.
Based on the derived analytical expression, we investigate the impact of the
various system parameters on the secrecy rate. Our analytical and simulation
results reveal that distributively deployed local oscillators (LOs) can achieve
a better performance than one common LO for all BS antennas as long as a
sufficient amount of power is assigned for data transmission.


title:
Personalized Advertisement Recommendation: A Ranking Approach to Address
  the Ubiquitous Click Sparsity Problem

abstract:
  We study the problem of personalized advertisement recommendation (PAR),
which consist of a user visiting a system (website) and the system displaying
one of $K$ ads to the user. The system uses an internal ad recommendation
policy to map the user's profile (context) to one of the ads. The user either
clicks or ignores the ad and correspondingly, the system updates its
recommendation policy. PAR problem is usually tackled by scalable
\emph{contextual bandit} algorithms, where the policies are generally based on
classifiers. A practical problem in PAR is extreme click sparsity, due to very
few users actually clicking on ads. We systematically study the drawback of
using contextual bandit algorithms based on classifier-based policies, in face
of extreme click sparsity. We then suggest an alternate policy, based on
rankers, learnt by optimizing the Area Under the Curve (AUC) ranking loss,
which can significantly alleviate the problem of click sparsity. We conduct
extensive experiments on public datasets, as well as three industry proprietary
datasets, to illustrate the improvement in click-through-rate (CTR) obtained by
using the ranker-based policy over classifier-based policies.


title:
Insurance Applications of Some New Dependence Models derived from
  Multivariate Collective Models

abstract:
  Consider two different portfolios which have claims triggered by the same
events. Their corresponding collective model over a fixed time period is given
in terms of individual claim sizes $(X_i,Y_i), i\ge 1$ and a claim counting
random variable $N$. In this paper we are concerned with the joint distribution
function $F$ of the \ece{largest claim sizes} $(X_{N:N}, Y_{N:N})$. By allowing
$N$ to depend on some parameter, say $\theta$, then $F=F(\theta)$ is for
various choices of $N$ a tractable parametric family of bivariate distribution
functions. We present three applications of the implied parametric models to
some data from the literature and a new data set from a Swiss insurance
company. Furthermore, we investigate both distributional and asymptotic
properties of $(X_{N:N}, Y_{N:N})$.


title: The Transfer is Functorial

abstract:
  We prove that the Becker-Gottlieb transfer is functorial up to homotopy, for
all fibrations with finitely dominated fibers. This resolves a lingering
foundational question about the transfer, which was originally defined in the
late 1970s in order to simplify the proof of the Adams conjecture. Our approach
differs from previous attempts in that we closely emulate the geometric
argument in the case of a smooth fiber bundle. This leads to a
"multiplicative'" description of the transfer, different from the standard
presentation as the trace of a diagonal map.


title: Tight fans and their canonical scalings

abstract:
  A new class of full fans in an euclidean space - tight fans - is introduced.
Such fans are defined using a property of local symmetry in a face of a tiling.
Tight fans are related to the theory of parallelotopes in an euclidean space. A
theorem is proved that a fan of cells meeting in a given face of a tiling by
parallelotopes is a tight fan. A new proof was given for a theorem by Delone on
5 combinatorial types of parallelotopes meeting in a common face of codimension
3.
  Canonical scalings of an euclidean space tiling are special functions defined
on hyperfaces of the tiling. Existance of such functions for a given tiling is
known to be related to existance of a generatix of a tiling. Generatix is a
polyhedral surface with an orthogonal projection coinciding with a given
tiling. A theroem is proved that a fan has a canonical scaling iff it is
polytopical.


title: Instrumental Variable with Competing Risk Model

abstract:
  In this paper, we discuss causal inference on the efficacy of a treatment or
medication on a time-to-event outcome with competing risks. Although the
treatment group can be randomized, there can be confoundings between the
compliance and the outcome. Unmeasured confoundings may exist even after
adjustment for measured co- variates. Instrumental variable (IV) methods are
commonly used to yield consistent estimations of causal parameters in the
presence of unmeasured confoundings. Based on a semi-parametric additive hazard
model for the subdistribution hazard, we pro- pose an instrumental variable
estimator to yield consistent estimation of efficacy in the presence of
unmeasured confoundings for competing risk settings. We derived the asymptotic
properties for the proposed estimator. The estimator is shown to be well per-
formed under finite sample size according to simulation results. We applied our
method to a real transplant data example and showed that the unmeasured
confoundings lead to significant bias in the estimation of the effect (about
50% attenuated).


title: Continuum Eigenmodes in Some Linear Stellar Models

abstract:
  We apply parallel approaches in the study of continuous spectra to adiabatic
stellar models. We seek continuum eigenmodes for the LAWE formulated as both
finite difference and linear differential equations. In particular, we apply
methods of Jacobi matrices and methods of subordinancy theory in these
respective formulations. We find certain pressure-density conditions which
admit positive-measured sets of continuous oscillation spectra under plausible
conditions on density and pressure. We arrive at results of unbounded
oscillations and computational or, perhaps, dynamic instability.


title:
PageRank Pipeline Benchmark: Proposal for a Holistic System Benchmark
  for Big-Data Platforms

abstract:
  The rise of big data systems has created a need for benchmarks to measure and
compare the capabilities of these systems. Big data benchmarks present unique
scalability challenges. The supercomputing community has wrestled with these
challenges for decades and developed methodologies for creating rigorous
scalable benchmarks (e.g., HPC Challenge). The proposed PageRank pipeline
benchmark employs supercomputing benchmarking methodologies to create a
scalable benchmark that is reflective of many real-world big data processing
systems. The PageRank pipeline benchmark builds on existing prior scalable
benchmarks (Graph500, Sort, and PageRank) to create a holistic benchmark with
multiple integrated kernels that can be run together or independently. Each
kernel is well defined mathematically and can be implemented in any programming
environment. The linear algebraic nature of PageRank makes it well suited to
being implemented using the GraphBLAS standard. The computations are simple
enough that performance predictions can be made based on simple computing
hardware models. The surrounding kernels provide the context for each kernel
that allows rigorous definition of both the input and the output for each
kernel. Furthermore, since the proposed PageRank pipeline benchmark is scalable
in both problem size and hardware, it can be used to measure and quantitatively
compare a wide range of present day and future systems. Serial implementations
in C++, Python, Python with Pandas, Matlab, Octave, and Julia have been
implemented and their single threaded performance has been measured.


title: Algebraic dimension of complex nilmanifolds

abstract:
  Let M be a complex nilmanifold, that is, a compact quotient of a nilpotent
Lie group endowed with an invariant complex structure by a discrete lattice. A
holomorphic differential on M is a closed, holomorphic 1-form. We show that
$a(M)\leq k$, where $a(M)$ is the algebraic dimension $a(M)$ (i.e. the
transcendence degree of the field of meromorphic functions) and $k$ is the
dimension of the space of holomorphic differentials. We prove a similar result
about meromorphic maps to Kahler manifolds.


title: Holomorphic minorants of plurisubharmonic functions

abstract:
  Let $\varphi$ be a plurisubharmonic function on a pseudoconvex domain $D
\subset \mathbb C^n$. We show that there exists a nonzero holomorphic function
$f$ on $D$ such that some local mean value of $\varphi$ with logarithmic
additional terms majorizes $\log |f|$. A similar problem is discussed for a
locally integrable function on $D$ in terms of balayage of positive measures.
Key words: holomorphic function, plurisubharmonicity, minorant, balayage,
Jensen inequality, mean value in the ball.


title:
Emergence time, curvature, space, causality, and complexity in encoding
  a discrete impulse information process

abstract:
  Interacting random field of probabilities links Kolmogorov law 0-1 and
Bayesian probabilities observing Markov diffusion process under Yes-No actions
of random impulse. These objective probabilities measure virtual probing
impulses processing the interactions in observable process. The impulse
observation increases each posteriori correlation reducing conditional entropy
measures from finite uncertainty up to certainty of real impulse. The reduced
entropy conveys probabilistic causality with time course and temporal memory in
collecting correlations, which interactive impulse innately cuts exposing
hidden process entropy. The natural cut of this entropy reveals information
hidden in the correlation connections. Inside the merging probing impulse
emerges reversible microprocess with yes-no conjugated entangled entropy,
curvature and logical complexity. Within the impulse time interval,
entanglement starts before its space is formed and ends with beginning the
space during reversible relative time interval being small part of impulse time
interval. Merging impulse curves and rotates the impulse interactive actions in
microprocess whose space interval measures this transitive movement.The cutting
entropy sequentially converting to information memorizes the probes logic in
Bit, participating in next probe conversions and encoding which memorizes
information causality. The complexity and mass appears after the space emerges
from the entanglement.The cognition assembles common units through the multiple
attraction and resonances at forming network (IN) of triplet hierarchy, which
accept only units that concentrates and recognizes each triplet IN node. The
ended triplet of hierarchical INs measures level of the observer intelligence.
The synthesized optimal process minimizes the observations time in Artificial
designed information Observer with intellectual searching logic.


title: Optimal sequence memory in driven random networks

abstract:
  Autonomous randomly coupled neural networks display a transition to chaos at
a critical coupling strength. We here investigate the effect of a time-varying
input on the onset of chaos and the resulting consequences for information
processing. Dynamic mean-field theory yields the statistics of the activity,
the maximum Lyapunov exponent, and the memory capacity of the network. We find
an exact condition that determines the transition from stable to chaotic
dynamics and the sequential memory capacity in closed form. The input
suppresses chaos by a dynamic mechanism, shifting the transition to
significantly larger coupling strengths than predicted by local stability
analysis. Beyond linear stability, a regime of coexistent locally expansive,
but non-chaotic dynamics emerges that optimizes the capacity of the network to
store sequential input.


title: Anderson localisation in spin chains for perfect state transfer

abstract:
  Anderson localisation is an important phenomenon arising in many areas of
physics, and here we explore it in the context of quantum information devices.
Finite dimensional spin chains have been demonstrated to be important devices
for quantum information transport, and in particular can be engineered to allow
for "perfect state transfer" (PST). Here we present extensive investigations of
disordered PST spin chains, demonstrating spatial localisation and transport
retardation effects, and relate these effects to conventional Anderson
localisation. We provide thresholds for Anderson localisation in these finite
quantum information systems for both the spatial and the transport domains.
Finally, we consider the effect of disorder on the eigenstate and energy
spectrum of our Hamiltonian, where results support our conclusions on the
presence of Anderson localisation.


title: Composing inference algorithms as program transformations

abstract:
  Probabilistic inference procedures are usually coded painstakingly from
scratch, for each target model and each inference algorithm. We reduce this
effort by generating inference procedures from models automatically. We make
this code generation modular by decomposing inference algorithms into reusable
program-to-program transformations. These transformations perform exact
inference as well as generate probabilistic programs that compute expectations,
densities, and MCMC samples. The resulting inference procedures are about as
accurate and fast as other probabilistic programming systems on real-world
problems.


title: Isomorphisms of Cayley graphs on nilpotent groups

abstract:
  Let S be a finite generating set of a torsion-free, nilpotent group G. We
show that every automorphism of the Cayley graph Cay(G;S) is affine. (That is,
every automorphism of the graph is obtained by composing a group automorphism
with multiplication by an element of the group.) More generally, we show that
if Cay(G;S) and Cay(G';S') are connected Cayley graphs of finite valency on two
nilpotent groups G and G', then every isomorphism from Cay(G;S) to Cay(G';S')
factors through to a well-defined affine map from G/N to G'/N', where N and N'
are the torsion subgroups of G and G', respectively. For the special case where
the groups are abelian, these results were previously proved by A.A.Ryabchenko
and C.Loeh, respectively.


title: Normal subgroups of invertibles and of unitaries in a C*-algebra

abstract:
  We investigate the normal subgroups of the groups of invertibles and
unitaries in the connected component of the identity. By relating normal
subgroups to closed two-sided ideals we obtain a "sandwich condition"
describing all the closed normal subgroups both in the invertible and in the
the unitary case. We use this to prove a conjecture by Elliott and Rordam: in a
simple C*-algebra, the group of approximately inner automorphisms induced by
unitaries in the connected component of the identity is topologically simple.
Turning to non-closed subgroups, we show, among other things, that in simple
unital C*-algebra the commutator subgroup of the group of invertibles in the
connected component of the identity is a simple group modulo its center. A
similar result holds for unitaries under a mild extra assumption.


title: Increasing coupling of probabilistic cellular automata

abstract:
  We give a necessary and sufficient condition for the existence of an
increasing coupling of $N$ ($N \geq 2$) synchronous dynamics on $S^{\mathbb
Z^d}$(PCA). Increasing means the coupling preserves stochastic ordering. We
first present our main construction theorem in the case where $S$ is totally
ordered, applications to attractive PCA's are given. When $S$ is only partially
ordered, we show on two examples that a coupling of more than two synchronous
dynamics may not exist. We also prove an extension of our main result for a
particular class of partially ordered spaces.


title: Path transformations for local times of one-dimensional diffusions

abstract:
  Let $X$ be a regular one-dimensional transient diffusion and $L^y$ be its
local time at $y$. The stochastic differential equation (SDE) whose solution
corresponds to the process $X$ conditioned on $[L^y_{\infty}=a]$ for a given
$a\geq 0$ is constructed and a new path decomposition result for transient
diffusions is given. In the course of the construction of the SDE the concept
of {\em recurrent transformation} is introduced and {\em Bessel-type motions}
as well as their SDE representations are studied. A remarkable link between an
$h$-transform with a minimal excessive function and recurrent transformations
is found, which, as a by-product, gives a useful representation of last passage
times as a mixture of first hitting times. Moreover, the Engelbert-Schmidt
theory for the weak solutions of one dimensional SDEs is extended to the case
when the initial condition is an entrance boundary for the diffusion. This
extension was necessary for the construction of the Bessel-type motion which
played an essential part in the SDE representation of $X$ conditioned on
$[L^y_{\infty}=a]$.


title: Concentrated Differential Privacy

abstract:
  We introduce Concentrated Differential Privacy, a relaxation of Differential
Privacy enjoying better accuracy than both pure differential privacy and its
popular "(epsilon,delta)" relaxation without compromising on cumulative privacy
loss over multiple computations.


title: Symmetries and Invariants in Higher-Spin Theory

abstract:
  General aspects of higher-spin gauge theory and unfolded formulation are
briefly recalled with some emphasize on the recent results on the breaking of
$sp(8)$ symmetry by current interactions and construction of invariant
functionals relevant to the higher-spin holography.


title:
The rate of convergence of some asymptotically chi-square distributed
  statistics by Stein's method

abstract:
  We build on recent works on Stein's method for functions of multivariate
normal random variables to derive bounds for the rate of convergence of some
asymptotically chi-square distributed statistics. We obtain some general bounds
and establish some simple sufficient conditions for convergence rates of order
$n^{-1}$ for smooth test functions. These general bounds are applied to
Friedman's statistic for comparing $r$ treatments across $n$ trials and the
family of power divergence statistics for goodness-of-fit across $n$ trials and
$r$ classifications, with index parameter $\lambda\in\mathbb{R}$ (Pearson's
statistic corresponds to $\lambda=1$). We obtain a $O(n^{-1})$ bound for the
rate of convergence of Friedman's statistic for any number of treatments
$r\geq2$. We also obtain a $O(n^{-1})$ bound on the rate of convergence of the
power divergence statistics for any $r\geq2$ when $\lambda$ is a positive
integer or any real number greater than 5. We conjecture that the $O(n^{-1})$
rate holds for any $\lambda\in\mathbb{R}$.


title: A Quantum Extended Kalman Filter

abstract:
  A stochastic filter uses a series of measurements over time to produce
estimates of unknown variables based on a dynamic model. For a quantum system,
such an algorithm is provided by a quantum filter, which is also known as a
stochastic master equation (SME). For a linear quantum system subject to linear
measurements and Gaussian noise, the quantum filter reduces to a quantum Kalman
filter. In this article, we introduce a quantum extended Kalman filter (quantum
EKF), which applies a commutative approximation and a time-varying
linearization to non-commutative quantum stochastic differential equations
(QSDEs). We will show that there are conditions under which a filter similar to
the classical EKF can be implemented for quantum systems. The boundedness of
estimation errors and the filtering problems with `state-dependent' covariances
for process and measurement noises are also discussed. We demonstrate the
effectiveness of the quantum EKF by applying it to systems which involve
multiple modes, nonlinear Hamiltonians and simultaneous jump-diffusive
measurements.


title:
Uniform approximations by Fourier sums on classes of generalized Poisson
  integrals

abstract:
  We find asymptotic equalities for exact upper bounds of approximations by
Fourier sums in uniform metric on classes of $2\pi$-periodic functions,
representable in the form of convolutions of functions $\varphi$, which belong
to unit balls of spaces $L_{p}$, with generalized Poisson kernels. For obtained
asymptotic equalities we introduce the estimates of remainder, which are
expressed in the explicit form via the parameters of the problem.


title: Monopole-Enriched Groundstates of Two-Dimensional BCS Models

abstract:
  We extract the macroscopic characteristics of the groundstate sectors of two
dimensional Bose-condensed BCS models with a fixed number of magnetic flux
quanta, on length scales much larger than the characteristic size of the
Cooper-pair bound states. We show that this reduces to the problem of computing
the moduli space of gauge-inequivalent solutions to the Gross-Pitaevskii
equations on a nontrivial fibre bundle. Inspired in part by the physical
arguments of Oshikawa and Senthil in Fractionalization, Topological Order, and
Quasiparticle Statistics, we extract a large class of groundstates from this
moduli space.


title:
Nuclear effects in Drell-Yan pair production in high-energy $pA$
  collisions

abstract:
  The Drell-Yan (DY) process of dilepton pair production off nuclei is not
affected by final state interactions, energy loss or absorption. A detailed
phenomenological study of this process is thus convenient for investigation of
the onset of initial-state effects in proton-nucleus ($pA$) collisions. In this
paper, we present a comprehensive analysis of the DY process in $pA$
interactions at RHIC and LHC energies in the color dipole framework. We analyse
several effects affecting the nuclear suppression, $R_{pA}<1$, of dilepton
pairs, such as the saturation effects, restrictions imposed by energy
conservation (the initial-state effective energy loss) and the gluon shadowing,
as a function of the rapidity, invariant mass of dileptons and their transverse
momenta $p_T$. In this analysis, we take into account besides the $\gamma^*$
also the $Z^0$ contribution to the production cross section, thus extending the
predictions to large dilepton invariant masses. Besides the nuclear attenuation
of produced dileptons at large energies and forward rapidities emerging due to
the onset of shadowing effects, we predict a strong suppression at large $p_T$,
dilepton invariant masses and Feynman $x_F$ caused by the Initial State
Interaction effects in kinematic regions where no shadowing is expected. The
manifestations of nuclear effects are investigated also in terms of the
correlation function in azimuthal angle between the dilepton pair and a forward
pion $\Delta\phi$ for different energies, dilepton rapidites and invariant
dilepton masses. We predict that the characteristic double-peak structure of
the correlation function around $\Delta \phi\simeq \pi$ arises for very forward
pions and large-mass dilepton pairs.


title: Faithful completely reducible representations of modular Lie algebras

abstract:
  The Ado-Iwasawa Theorem asserts that a finite-dimensional Lie algebra $L$
over a field $F$ has a finite-dimensional faithful module $V$. There are
several extensions asserting the existence of such a module with various
additional properties. In particular, Jacobson has proved that if the field has
characteristic $p>0$, then there exists a completely reducible such module $V$.
I strengthen Jacobson's Theorem, proving that if $L$ has dimension $n$ over the
field $F$ of characteristic $p>0$, then $L$ has a faithful completely reducible
module $V$ with $\dim(V) \le p^{n^2-1}$.


title: Bounds on the Voter Model in Dynamic Networks

abstract:
  In the voter model, each node of a graph has an opinion, and in every round
each node chooses independently a random neighbour and adopts its opinion. We
are interested in the consensus time, which is the first point in time where
all nodes have the same opinion. We consider dynamic graphs in which the edges
are rewired in every round (by an adversary) giving rise to the graph sequence
$G_1, G_2, \dots $, where we assume that $G_i$ has conductance at least
$\phi_i$. We assume that the degrees of nodes don't change over time as one can
show that the consensus time can become super-exponential otherwise. In the
case of a sequence of $d$-regular graphs, we obtain asymptotically tight
results. Even for some static graphs, such as the cycle, our results improve
the state of the art. Here we show that the expected number of rounds until all
nodes have the same opinion is bounded by $O(m/(d_{min} \cdot \phi))$, for any
graph with $m$ edges, conductance $\phi$, and degrees at least $d_{min}$. In
addition, we consider a biased dynamic voter model, where each opinion $i$ is
associated with a probability $P_i$, and when a node chooses a neighbour with
that opinion, it adopts opinion $i$ with probability $P_i$ (otherwise the node
keeps its current opinion). We show for any regular dynamic graph, that if
there is an $\epsilon>0$ difference between the highest and second highest
opinion probabilities, and at least $\Omega(\log n)$ nodes have initially the
opinion with the highest probability, then all nodes adopt w.h.p. that opinion.
We obtain a bound on the convergences time, which becomes $O(\log n/\phi)$ for
static graphs.


title:
The existence and decay rates of strong solutions for Navier-Stokes
  Equations in Bessel-potential spaces

abstract:
  In this paper, we prove some results on the existence and decay properties of
high order derivatives in time and space variables for local and global
solutions of the Cauchy problem for the Navier-Stokes equations in
Bessel-potential spaces.


title:
Bias Correction of Semiparametric Long Memory Parameter Estimators via
  the Pre-filtered Sieve Bootstrap

abstract:
  This paper investigates bootstrap-based bias correction of semiparametric
estimators of the long memory parameter, $d$, in fractionally integrated
processes. The re-sampling method involves the application of the sieve
bootstrap to data pre-filtered by a preliminary semiparametric estimate of the
long memory parameter. Theoretical justification for using the bootstrap
technique to bias adjust log periodogram and semiparametric local Whittle
estimators of the memory parameter is provided in the case where the true value
of $d$ lies in the range $0\leq d<0.5$. That the bootstrap method provides
confidence intervals with the correct asymptotic coverage is also proven, with
the intervals shown to adjust explicitly for bias, as estimated via the
bootstrap. Simulation evidence comparing the performance of the bootstrap bias
correction with analytical bias-correction techniques is presented. The
bootstrap method is shown to produce notable bias reductions, in particular
when applied to an estimator for which some degree of bias reduction has
already been accomplished by analytical means.


title:
A new insight into neutrino energy loss by electron capture of iron
  group nuclei in magnetars surface

abstract:
  Based on the relativistic mean-field effective interactions theory, and Lai
dong model \citep{b37, b38, b39}, we discuss the influences of superstrong
magnetic fields (SMFs) on electron Fermi energy, nuclear blinding energy, and
single-particle level structure in magnetars surface. By using the method of
Shell-Model Monte Carlo (SMMC), and the Random Phase Approximation (RPA)
theory, we detailed analyze the neutrino energy loss rates(NELRs) by electron
capture (EC) for iron group nuclei in SMFs.


title: Minimal energy configurations of finite molecular arrays

abstract:
  In this paper we consider the problem of characterizing the minimum energy
configurations of a finite system of particles interacting between them due to
attracting or repulsive forces given by a certain inter molecular potential. We
limit ourselves to the cases of three particles arranged in a triangular array
and that of four particles in a tetrahedral array. The minimization is
constrained to fixed area in the case of the triangular array, and to fixed
volume in the tetrahedral case. For a general class of inter molecular
potentials we give conditions for the homogeneous configuration (either an
equilateral triangle or a regular tetrahedron) of the array to be stable, that
is, a minimizer of the potential energy of the system. To determine whether or
not there exist other stable states, the system of first order necessary
conditions for a minimum is treated as a bifurcation problem with the area or
volume variable as the bifurcation parameter. Because of the symmetries present
in our problem, we can apply the techniques of equivariant bifurcation theory
to show that there exist branches of non--homogeneous solutions bifurcating
from the trivial branch of homogeneous solutions at precisely the values of the
parameter of area or volume for which the homogeneous configuration changes
stability. For the triangular array, we construct numerically the bifurcation
diagrams for both a Lennard--Jones and Buckingham potentials. The numerics show
that there exist non--homogeneous stable states, multiple stable states for
intervals of values of the area parameter, and secondary bifurcations as well.


title: Analysis of a Double Kruskal Theorem

abstract:
  The strength of an extension of Kruskal's Theorem to certain pairs of
cohabitation trees is calibrated.


title:
Confidence-Constrained Maximum Entropy Framework for Learning from
  Multi-Instance Data

abstract:
  Multi-instance data, in which each object (bag) contains a collection of
instances, are widespread in machine learning, computer vision, bioinformatics,
signal processing, and social sciences. We present a maximum entropy (ME)
framework for learning from multi-instance data. In this approach each bag is
represented as a distribution using the principle of ME. We introduce the
concept of confidence-constrained ME (CME) to simultaneously learn the
structure of distribution space and infer each distribution. The shared
structure underlying each density is used to learn from instances inside each
bag. The proposed CME is free of tuning parameters. We devise a fast
optimization algorithm capable of handling large scale multi-instance data. In
the experimental section, we evaluate the performance of the proposed approach
in terms of exact rank recovery in the space of distributions and compare it
with the regularized ME approach. Moreover, we compare the performance of CME
with Multi-Instance Learning (MIL) state-of-the-art algorithms and show a
comparable performance in terms of accuracy with reduced computational
complexity.


title: Flowing in Group Field Theory Space: a Review

abstract:
  We provide a non-technical overview of recent extensions of renormalization
methods and techniques to Group Field Theories (GFTs), a class of
combinatorially non-local quantum field theories which generalize matrix models
to dimension $d \geq 3$. More precisely, we focus on GFTs with so-called
closure constraint, which are closely related to lattice gauge theories and
quantum gravity spin foam models. With the help of recent tensor model tools, a
rich landscape of renormalizable theories has been unravelled. We review our
current understanding of their renormalization group flows, at both
perturbative and non-perturbative levels.


title:
Approximate but Accurate Quantum Dynamics from the Mori Formalism: I.
  Nonequilibrium Dynamics

abstract:
  We present a formalism that explicitly unifies the commonly used
Nakajima-Zwanzig approach for reduced density matrix dynamics with the more
versatile Mori theory in the context of nonequilibrium dynamics. Employing a
Dyson-type expansion to circumvent the difficulty of projected dynamics, we
obtain a self-consistent equation for the memory kernel which requires only
knowledge of normally evolved auxiliary kernels. To illustrate the properties
of the current approach, we focus on the spin-boson model and limit our
attention to the use of a simple and inexpensive quasi-classical dynamics,
given by the Ehrenfest method, for the calculation of the auxiliary kernels.
For the first time, we provide a detailed analysis of the dependence of the
properties of the memory kernels obtained via different projection operators,
namely the thermal (Redfield-type) and population based (NIBA-type) projection
operators. We further elucidate the conditions that lead to short-lived memory
kernels and the regions of parameter space to which this program is best
suited. Via a thorough analysis of the different closures available for the
auxiliary kernels and the convergence properties of the self-consistently
extracted memory kernel, we identify the mechanisms whereby the current
approach leads to a significant improvement over the direct usage of standard
semi- and quasi-classical dynamics.


title: Continuum-wise expansiveness for generic diffeomorphisms

abstract:
  Let $M$ be a closed smooth manifold and let $f:M\to M$ be a diffeomorphism.
$C^1$-generically, a continuum-wise expansive satisfies Axiom A without cycles.
Moreover, there is a partially hyperbolic diffeomorphism $f$ such that it is
not continuum-wise expansive.


title:
Generalized Quantum Master Equations In and Out of Equilibrium: When Can
  One Win?

abstract:
  Generalized quantum master equations (GQMEs) are an important tool in
modeling chemical and physical processes. For a large number of problems it has
been shown that exact and approximate quantum dynamics methods can be made
dramatically more efficient, and in the latter case more accurate, by
proceeding via the GQME formalism. However, there are many situations where
utilizing the GQME approach seems to offer no advantage over a direct
evaluation of the property of interest. Here we provide a more detailed
understanding of the conditions under which these methods will offer benefits.
In particular, we derive exact expressions for the memory kernel for systems
both in and out of equilibrium, and show the conditions under which these
expressions will be guaranteed to return a result identical to that obtained
from direct simulation. We also show the conditions which approximate methods
must satisfy if they are to offer different results when used in conjunction
with the GQME formalism. These exact analytical results thus provide new
insights as to when proceeding via the GQME approach can improve the accuracy
or efficiency of simulations.


title:
Large-area, uniform and low-cost dual-mode plasmonic naked-eye
  colorimetry and SERS sensor with handheld Raman spectrometer

abstract:
  We demonstrated a highly sensitive, waferscale, highly uniform plasmonic
nanomushroom substrate based on plastic for nakedeye plasmonic colorimetry and
surface enhanced Raman spectroscopy (SERS). We gave it the name FlexBrite. The
dualmode functionality of FlexBrite allows for label-free qualitative analysis
by SERS with an enhancement factor (EF) of 10^8 and labelfree quantitative
analysis by naked eye colorimetry with a sensitivity of 611 nm RIU-1. The SERS
EF of FlexBrite in the wet state was found to be 4.81 X 10^8, 7 times stronger
than in the dry state, making FlexBrite suitable for aqueous environments such
as microfluid systems. The labelfree detection of biotin streptavidin
interaction by both SERS and colorimetry was demonstrated with FlexBrite. The
detection of trace amounts of the narcotic drug methamphetamine in drinking
water by SERS was implemented with a handheld Raman spectrometer and FlexBrite.
This plastic based dual-mode nano-mushroom substrate has the potential to be
used as a sensing platform for easy and fast analysis in chemical and
biological assays.


title:
Equilateral triangles in subsets of ${\Bbb R}^d$ of large Hausdorff
  dimension

abstract:
  We prove that subsets of ${\Bbb R}^d$, $d \ge 4$ of large enough Hausdorff
dimensions contain vertices of an equilateral triangle. It is known that
additional hypotheses are needed to assure the existence of equilateral
triangles in two dimensions (see \cite{CLP14}). We show that no extra
conditions are needed in dimensions four and higher. The three dimensional case
remains open.
  Some interesting parallels exist between the triangle problem in Euclidean
space and its counter-part in vector spaces over finite fields. We shall
outline these similarities in hopes of eventually achieving a comprehensive
understanding of this phenomenon in the setting of locally compact abelian
groups.


title:
Finite time blowup for high dimensional nonlinear wave systems with
  bounded smooth nonlinearity

abstract:
  We consider the global regularity problem for nonlinear wave systems $$ \Box
u = f(u) $$ on Minkowski spacetime ${\bf R}^{1+d}$ with d'Alambertian $\Box :=
-\partial_t^2 + \sum_{i=1}^d \partial_{x_i}^2$, where the field $u \colon {\bf
R}^{1+d} \to {\bf R}^m$ is vector-valued, and the nonlinearity $f \colon {\bf
R}^m \to {\bf R}^m$ is a smooth function with $f(0)=0$ and all derivatives
bounded; the higher-dimensional sine-Gordon equation $\Box u = \sin u$ is a
model example of this class of nonlinear wave system. For dimensions $d \leq
9$, it follows from the work of Heinz, Pecher, Brenner, and von Wahl that one
has smooth solutions to this equation for any smooth choice of initial data.
Perhaps surprisingly, we show that this result is almost sharp, in the sense
that for any $d \geq 11$, there exists an $m$ (in fact we can take $m=2$) and a
nonlinearity $f \colon {\bf R}^m \to {\bf R}^m$ with all derivatives bounded,
for which the above equation admits solutions that blow up in finite time. The
intermediate case $d=10$ remains open.


title:
Optimal Load and Stiffness for Displacement-Constrained Vibration Energy
  Harvesters

abstract:
  The power electronic interface to a vibration energy harvester not only
provides ac-dc conversion, but can also set the electrical damping to maximize
output power under displacement-constrained operation. This is commonly
exploited for linear two-port harvesters by synchronous switching to realize a
Coulomb-damped resonant generator, but has not been fully explored when the
harvester is asynchronously switched to emulate a resistive load. In order to
understand the potential of such an approach, the optimal values of load
resistance and other control parameters need to be known. In this paper we
determine analytically the optimal load and stiffness of a harmonically driven
two-port harvester with displacement constraints. For weak-coupling devices, we
do not find any benefit of load and stiffness adjustment beyond maintaining a
saturated power level. For strong coupling we find that the power can be
optimized to agree with the velocity damped generator beyond the first critical
force for displacement-constrained operation. This can be sustained up to a
second critical force, determined by a resonator figure-of-merit, at which the
power ultimately levels out.


title:
Supermassive black holes and their host spheroids III. The $M_{BH} -
  n_{sph}$ correlation

abstract:
  The S\'ersic $R^{1/n}$ model is the best approximation known to date for
describing the light distribution of stellar spheroidal and disk components,
with the S\'ersic index $n$ providing a direct measure of the central radial
concentration of stars. The S\'ersic index of a galaxy's spheroidal component,
$n_{sph}$, has been shown to tightly correlate with the mass of the central
supermassive black hole, $M_{BH}$. The $M_{BH}-n_{sph}$ correlation is also
expected from other two well known scaling relations involving the spheroid
luminosity, $L_{sph}$: the $L_{sph}-n_{sph}$ and the $M_{BH}-L_{sph}$.
Obtaining an accurate estimate of the spheroid S\'ersic index requires a
careful modelling of a galaxy's light distribution and some studies have failed
to recover a statistically significant $M_{BH}-n_{sph}$ correlation. With the
aim of re-investigating the $M_{BH}-n_{sph}$ and other black hole mass scaling
relations, we performed a detailed (i.e.~bulge, disks, bars, spiral arms,
rings, halo, nucleus, etc.) decomposition of 66 galaxies, with directly
measured black hole masses, that had been imaged at $3.6\rm~\mu m$ with
Spitzer. In this paper, the third of this series, we present an analysis of the
$L_{sph}-n_{sph}$ and $M_{BH}-n_{sph}$ diagrams. While early-type
(elliptical+lenticular) and late-type (spiral) galaxies split into two separate
relations in the $L_{sph}-n_{sph}$ and $M_{BH}-L_{sph}$ diagrams, they reunite
into a single $M_{BH} \propto n_{sph}^{3.39 \pm 0.15}$ sequence with relatively
small intrinsic scatter ($\epsilon \simeq 0.25 \rm~dex$). The black hole mass
appears to be closely related to the spheroid central concentration of stars,
which mirrors the inner gradient of the spheroid gravitational potential.


title: Hanabi is NP-hard, Even for Cheaters who Look at Their Cards

abstract:
  In this paper we study a cooperative card game called Hanabi from the
viewpoint of algorithmic combinatorial game theory. In Hanabi, each card has
one among $c$ colors and a number between $1$ and $n$. The aim is to make, for
each color, a pile of cards of that color with all increasing numbers from $1$
to $n$. At each time during the game, each player holds $h$ cards in hand.
Cards are drawn sequentially from a deck and the players should decide whether
to play, discard or store them for future use. One of the features of the game
is that the players can see their partners' cards but not their own and
information must be shared through hints.
  We introduce a single-player, perfect-information model and show that the
game is intractable even for this simplified version where we forego both the
hidden information and the multiplayer aspect of the game, even when the player
can only hold two cards in her hand. On the positive side, we show that the
decision version of the problem---to decide whether or not numbers from $1$
through $n$ can be played for every color---can be solved in (almost) linear
time for some restricted cases.


title: Partition Functions from Rao-Blackwellized Tempered Sampling

abstract:
  Partition functions of probability distributions are important quantities for
model evaluation and comparisons. We present a new method to compute partition
functions of complex and multimodal distributions. Such distributions are often
sampled using simulated tempering, which augments the target space with an
auxiliary inverse temperature variable. Our method exploits the multinomial
probability law of the inverse temperatures, and provides estimates of the
partition function in terms of a simple quotient of Rao-Blackwellized marginal
inverse temperature probability estimates, which are updated while sampling. We
show that the method has interesting connections with several alternative
popular methods, and offers some significant advantages. In particular, we
empirically find that the new method provides more accurate estimates than
Annealed Importance Sampling when calculating partition functions of large
Restricted Boltzmann Machines (RBM); moreover, the method is sufficiently
accurate to track training and validation log-likelihoods during learning of
RBMs, at minimal computational cost.


title:
A Latent Variable Recurrent Neural Network for Discourse Relation
  Language Models

abstract:
  This paper presents a novel latent variable recurrent neural network
architecture for jointly modeling sequences of words and (possibly latent)
discourse relations between adjacent sentences. A recurrent neural network
generates individual words, thus reaping the benefits of
discriminatively-trained vector representations. The discourse relations are
represented with a latent variable, which can be predicted or marginalized,
depending on the task. The resulting model can therefore employ a training
objective that includes not only discourse relation classification, but also
word prediction. As a result, it outperforms state-of-the-art alternatives for
two tasks: implicit discourse relation classification in the Penn Discourse
Treebank, and dialog act classification in the Switchboard corpus. Furthermore,
by marginalizing over latent discourse relations at test time, we obtain a
discourse informed language model, which improves over a strong LSTM baseline.


title: A superconvergent HDG method for the Maxwell equations

abstract:
  We present and analyze a new hybridizable discontinuous Galerkin (HDG) method
for the steady state Maxwell equations. In order to make the problem
well-posed, a condition of divergence is imposed on the electric field. Then a
Lagrange multiplier $p$ is introduced, and the problem becomes the solution of
a mixed curl-curl formulation of the Maxwell's problem. We use polynomials of
degree $k+1$, $k$, $k$ to approximate $\bfu,\nabla \times \bfu$ and $p$
respectively. In contrast, we only use a non-trivial subspace of polynomials of
degree $k+1$ to approximate the numerical tangential trace of the electric
field and polynomials of degree $k+1$ to approximate the numerical trace of the
Lagrange multiplier on the faces. On the simplicial meshes, a special choice of
the stabilization parameters is applied, and the HDG system is shown to be
well-posed. Moreover, we show that the convergence rates for $\boldsymbol{u}$
and $\nabla \times \boldsymbol{u}$ are independent of the Lagrange multiplier
$p$. If we assume the dual operator of the Maxwell equation on the domain has
adequate regularity, we show that the convergence rate for $\boldsymbol{u}$ is
$O(h^{k+2})$. From the point of view of degrees of freedom of the globally
coupled unknown: numerical trace, this HDG method achieves superconvergence for
the electric field without postprocessing. Finally, we show that on general
polyhedral elements, by a particular choice of the stabilization parameters
again, the HDG system is also well-posed and the superconvergence of the HDG
method is derived.


title: On the efficient acceleration of clouds in active galactic nuclei

abstract:
  In the broad line region of AGN, acceleration occurs naturally when a cloud
condenses out of the hot confining medium due to the increase in line opacity
as the cloud cools. However, acceleration by radiation pressure is not very
efficient when the flux is time-independent, unless the flow is
one-dimensional. Here we explore how acceleration is affected by a time-varying
flux, as AGN are known to be highly variable. If the period of flux
oscillations is longer than the thermal timescale, we expect the gas to cool
during the low flux state, and therefore line opacity should quickly increase.
The cloud will receive a small kick due to the increased radiation force. We
perform hydrodynamical simulations using Athena to confirm this effect and
quantify its importance. We find that despite the flow becoming turbulent in 2D
due to hydrodynamic instabilities, a 20% modulation of the flux leads to a net
increase in acceleration --- by more than a factor of 2 --- in both 1D and 2D.
We show that this is sufficient to produce the observed line widths, although
we only consider optically thin clouds. We discuss the implications of our
results for photoionization modeling and reverberation mapping.


title:
Amplification, Decoherence, and the Acquisition of Information by Spin
  Environments

abstract:
  Quantum Darwinism recognizes the role of the environment as a communication
channel: Decoherence can selectively amplify information about the pointer
states of a system of interest (preventing access to complementary information
about their superpositions) and can make records of this information accessible
to many observers. This redundancy explains the emergence of objective,
classical reality in our quantum Universe. Here, we demonstrate that the
amplification of information in realistic spin environments can be quantified
by the quantum Chernoff information, which characterizes the distinguishability
of partial records in individual environment subsystems. We show that, except
for a set of initial states of measure zero, the environment always acquires
redundant information. Moreover, the Chernoff information captures the rich
behavior of amplification in both finite and infinite spin environments, from
quadratic growth of the redundancy to oscillatory behavior. These results will
considerably simplify experimental testing of quantum Darwinism, e.g., using
nitrogen vacancies in diamond.


title: VIEWPOINT: A New Twist in Simulating Solar Flares

abstract:
  Simulations show for the first time how the magnetic fields that produce
solar flares can extend out of the Sun by acquiring a twist.


title:
Dynamical mass ejection from the merger of asymmetric binary neutron
  stars: Radiation-hydrodynamics study in general relativity

abstract:
  We perform neutrino radiation-hydrodynamics simulations for the merger of
asymmetric binary neutron stars in numerical relativity. Neutron stars are
modeled by soft and moderately stiff finite-temperature equations of state
(EOS). We find that the properties of the dynamical ejecta such as the total
mass, neutron richness profile, and specific entropy profile depend on the mass
ratio of the binary systems for a given EOS in a unique manner. For the soft
EOS (SFHo), the total ejecta mass depends weakly on the mass ratio, but the
average of electron number per baryon ($Y_e$) and specific entropy ($s$) of the
ejecta decreases significantly with the increase of the degree of mass
asymmetry. For the stiff EOS (DD2), with the increase of the mass asymmetry
degree, the total ejecta mass significantly increases while the average of
$Y_e$ and $s$ moderately decreases. We find again that only for the soft EOS
(SFHo), the total ejecta mass exceeds $0.01M_\odot$ irrespective of the mass
ratio chosen in this paper. The ejecta have a variety of electron number per
baryon with its average approximately between $Y_e \sim 0.2$ and $\sim 0.3$
irrespective of the EOS employed, which is well-suited for the production of
the r-process heavy elements (second and third peaks), although its averaged
value decreases with the increase of the degree of mass asymmetry.

categories: astro-ph.HE astro-ph.CO astro-ph.SR gr-qc


title:
Parton distribution functions probed in ultraperipheral collisions at
  the CERN Large Hadron Collider

abstract:
  Vector meson production in ultra-peripheral pA and AA collisions at the CERN
Large Hadron Collider (LHC) are very sensitive to Parton Distribution Functions
(PDF) as well as to their leading-order, next-to-leading-order, and medium
corrections. This process is a complimentary tool to explore the effects of
different PDFs in particle production in proton-nucleus and nucleus-nucleus
central collisions. Existing and forthcoming data available, e.g., from ALICE
and CMS, may be used in conjunction with our theoretical predictions to
constrain the PDFs. We make predictions for rapidity distributions and for
cross sections of J/$\psi$ , $\psi(2S)$ and $\Upsilon$ production at
$\sqrt{s_{NN}}=2.76$ TeV and $\sqrt{s_{NN}}=5$ TeV. We use the second energy as
representative for the Run 2 of PbPb collisions at the LHC.


title:
Full jet evolution in quark-gluon plasma and nuclear modification of jet
  production and jet shape in Pb+Pb collisions at 2.76 ATeV at the LHC

abstract:
  We study the evolution of full jet shower in quark-gluon plasma via solving a
set of coupled differential transport equations for the three-dimensional
momentum distributions of quarks and gluons contained in the full jets. In our
jet evolution equations, we include all partonic splitting processes as well as
the collisional energy loss and transverse momentum broadening for both the
leading and radiated partons of the full jets. Combining with a realistic
(2+1)-dimensional viscous hydrodynamic simulation for the space-time profiles
of the hot and dense nuclear medium produced in heavy-ion collisions, we apply
our formalism to calculate the nuclear modification of single inclusive full
jet spectra, the momentum imbalance of photon-jet and dijet pairs, and jet
shape function (at partonic level) in Pb+Pb collisions at 2.76 ATeV. The roles
of various jet-medium interaction mechanisms on the full jet modification are
studied. We find that the nuclear modification of jet shape is sensitive to the
interplay of different interaction mechanisms as well as the energies of the
full jets.


title: Optimal Geographic Caching in Finite Wireless Networks

abstract:
  Cache-enabled device-to-device (D2D) networks turn memory of the devices at
the network edge, such as smart phones and tablets, into bandwidth by enabling
asynchronous content sharing directly between proximate devices. Limited
storage capacity of the mobile devices necessitates the determination of
optimal set of contents to be cached on each device. In order to study the
problem of optimal cache placement, we model the locations of devices in a
finite region (e.g., coffee shop, sports bar, library) as a uniform binomial
point process (BPP). For this setup, we first develop a generic framework to
analyze the coverage probability of the target receiver (target-Rx) when the
requested content is available at the $k^{th}$ closest device to it. Using this
coverage probability result, we evaluate optimal caching probability of the
popular content to maximize the total hit probability. Our analysis concretely
demonstrates that optimal caching probability strongly depends on the number of
simultaneously active devices in the network.


title:
Regularity of solutions to time-harmonic Maxwell's system with various
  lower than Lipschitz coefficients

abstract:
  In this paper, we study the regularity of the solutions of Maxwell's
equations in a bounded domain. We consider several different types of low
regularity assumptions to the coefficients which are all less than Lipschitz.
We first develop a new approach by giving $\mathcal{H}^1$ estimate when the
coefficients are $\mathcal{L}^{\infty}$ bounded; and then we derive
$\mathcal{W}^{1,p}$ estimates for every $p > 2$ when one of the leading
coefficients is simply continuous; Finally, we extend the result to
$\mathcal{C}^{1,\alpha}$ almost everywhere for the solution of the homogeneous
Maxwell's equations when the coefficients are $\mathcal{W}^{1,p}, \, p>3$ and
close to the identity matrix in the sense of $\mathcal{L}^{\infty}$ norm. The
last two estimates are new, and the techniques and methods developed here can
also be applied to other problems with similar difficulties.


title:
Cyclotron maser emission from power-law electrons with strong
  pitch-angle anisotropy

abstract:
  Energetic electrons with power-law spectrum are most commonly observed in
astrophysics. This paper investigates electron cyclotron maser emission (ECME)
from the power-law electrons, in which strong pitch-angle anisotropy is
emphasized. The electron distribution function proposed in this paper can
describe various types of pitch-angle anisotropy. Results show that the
emission properties of ECME, including radiation growth, propagation, and
frequency properties, depend considerably on the types of electron pitch-angle
anisotropy, and different wave modes show different dependences on the pitch
angle of electrons. In particular, the maximum growth rate of X2 mode rapidly
decreases with respect to the electron pitch-angle cosine $\mu_0$ at which the
electron distribution peaks, while the growth rates for other modes (X1, O1,
O2) initially increase before decreasing as $\mu_0$ increases. Moreover, the O
mode as well as the X mode can be the fastest growth mode, in terms of not only
the plasma parameter but also the type of electron pitch-angle distribution.
This result presents a significant extension of the recent researches on ECME
driven by the lower-energy cutoff of power-law electrons, in which the X mode
is generally the fastest growth mode.

categories: astro-ph.SR astro-ph.HE physics.plasm-ph physics.space-ph


title:
Study of compound nucleus formation via bremsstrahlung emission in
  proton $\alpha$-particle scattering

abstract:
  In this paper a role of many-nucleon dynamics in formation of the compound
$^{5}{\rm Li}$ nucleus in the scattering of protons off $\alpha$-particles at
the proton incident energies up to 20 MeV is investigated. We propose a
bremsstrahlung model allowing to extract information about probabilities of
formation of such nucleus on the basis of analysis of experimental
cross-sections of the bremsstrahlung photons. In order to realize this
approach, the model includes elements of microscopic theory and also
probabilities of formation of the short-lived compound nucleus. Results of
calculations of the bremsstrahlung spectra are in good agreement with the
experimental cross-sections.


title: On the Complexity of Detecting Constrained Negative Cost Cycles

abstract:
  Given a positive integer $k$ and a directed graph with a cost on each edge,
the $k$-length negative cost cycle ($k$\emph{LNCC}) problem is to determine
whether there exists a negative cost cycle with at least $k$ edges, and the
fixed-point \emph{$k$-}length negative cost cycle \emph{trail (FP$k$LNCCT)}
problem is to determine whether there exists a negative trail enrouting a given
vertex (as the fixed point) and containing only cycles with at least $k$ edges.
The $k$\emph{LNCC} problem first emerged in deadlock avoidance in synchronized
streaming computing network \cite{spaa10}, generalizing two famous problems:
negative cycle detection and the $k$-cycle problem. As a warmup by-production,
the paper first shows that \emph{FP$k$LNCCT is }${\cal NP}$-complete in
multigraph\emph{ }even for\emph{ $k=3$} by reducing from the \emph{3SAT}
problem. Then as the main result, we prove the ${\cal NP}$-completeness of
$k$\emph{LNCC} by giving a sophisticated reduction from the 3 Occurrence
3-Satisfiability (\emph{3O3SAT}) problem, a known ${\cal NP}$-complete special
case of 3SAT in which a variable occurs at most three times. The complexity
result is interesting, since polynomial time algorithms are known for both
$2$\emph{LNCC} (essentially no restriction on the value of $k$) and the
$k$-cycle problem of fixed $k$. This paper closes the open problem proposed by
Li et al. in \cite{spaa10} whether $k$\emph{LNCC} admits polynomial-time
algorithms.


title:
Millimeter Wave MIMO Channel Estimation using Overlapped Beam Patterns
  and Rate Adaptation

abstract:
  This paper is concerned with the channel estimation problem in Millimeter
wave (mmWave) wireless systems with large antenna arrays. By exploiting the
inherent sparse nature of the mmWave channel, we first propose a fast channel
estimation (FCE) algorithm based on a novel overlapped beam pattern design,
which can increase the amount of information carried by each channel
measurement and thus reduce the required channel estimation time compared to
the existing non-overlapped designs. We develop a maximum likelihood (ML)
estimator to optimally extract the path information from the channel
measurements. Then, we propose a novel rate-adaptive channel estimation (RACE)
algorithm, which can dynamically adjust the number of channel measurements
based on the expected probability of estimation error (PEE). The performance of
both proposed algorithms is analyzed. For the FCE algorithm, an approximate
closed-form expression for the PEE is derived. For the RACE algorithm, a lower
bound for the minimum signal energy-to-noise ratio required for a given number
of channel measurements is developed based on the Shannon-Hartley theorem.
Simulation results show that the FCE algorithm significantly reduces the number
of channel estimation measurements compared to the existing algorithms using
non-overlapped beam patterns. By adopting the RACE algorithm, we can achieve up
to a 6dB gain in signal energy-to-noise ratio for the same PEE compared to the
existing algorithms.


title:
Estimating space-time parameters with a quantum probe in a lossy
  environment

abstract:
  We study the problem of estimating the Schwarzschild radius of a massive body
using Gaussian quantum probe states. Previous calculations assumed that the
probe state remained pure after propagating a large distance. In a realistic
scenario, there would be inevitable losses. Here we introduce a practical
approach to calculate the Quantum Fisher Informations (QFIs) for a quantum
probe that has passed through a lossy channel. Whilst for many situations loss
means coherent states are optimal, we identify certain situations for which
squeezed states have an advantage. We also study the effect of the frequency
profile of the wavepacket propagating from Alice to Bob. There exists an
optimal operating point for a chosen mode profile. In particular, employing a
smooth rectangular frequency profile significantly improves the error bound on
the Schwarzschild radius compared to a Gaussian frequency profile.


title: Smartphone microendoscopy for high resolution fluorescence imaging

abstract:
  High resolution optical endoscopes are increasingly used in diagnosis of
various medical conditions of internal organs, such as the gastrointestinal
tracts, but they are too expensive for use in resource-poor settings. On the
other hand, smartphones with high resolution cameras and Internet access have
become more affordable, enabling them to diffuse into most rural areas and
developing countries in the past decade. In this letter we describe a
smartphone microendoscope that can take fluorescence images with a spatial
resolution of 3.1 {\mu}m. Images collected from ex vivo, in vitro and in vivo
samples using the device are also presented. The compact and cost-effective
smartphone microendoscope may be envisaged as a powerful tool for detecting
pre-cancerous lesions of internal organs in low and middle income countries.


title: Temporal Opinion Spam Detection by Multivariate Indicative Signals

abstract:
  Online consumer reviews reflect the testimonials of real people, unlike
advertisements. As such, they have critical impact on potential consumers, and
indirectly on businesses. According to a Harvard study (Luca 2011), +1 rise in
star-rating increases revenue by 5-9%. Problematically, such financial
incentives have created a market for spammers to fabricate reviews, to unjustly
promote or demote businesses, activities known as opinion spam (Jindal and Liu
2008). A vast majority of existing work on this problem have formulations based
on static review data, with respective techniques operating in an offline
fashion. Spam campaigns, however, are intended to make most impact during their
course. Abnormal events triggered by spammers' activities could be masked in
the load of future events, which static analysis would fail to identify. In
this work, we approach the opinion spam problem with a temporal formulation.
Specifically, we monitor a list of carefully selected indicative signals of
opinion spam over time and design efficient techniques to both detect and
characterize abnormal events in real-time. Experiments on datasets from two
different review sites show that our approach is fast, effective, and practical
to be deployed in real-world systems.


title:
Structure of correlated initial states that guarantee completely
  positive reduced dynamics

abstract:
  We use the Koashi-Imoto decomposition of the degrees of freedom of joint
system-environment initial states to investigate the reduced dynamics. We show
that a subset of joint system-environment initial states guarantees completely
positive reduced dynamics, if and only if the system privately owns all quantum
degrees of freedom and can locally access the classical degrees of freedom,
without disturbing all joint initial states in the given subset. Furthermore,
we show that the quantum mutual information for such kinds of states must be
independent of the quantum degrees of freedom.


title: Stochastic Collection and Replenishment (SCAR): Objective Functions

abstract:
  This paper introduces two objective functions for computing the expected cost
in the Stochastic Collection and Replenishment (SCAR) scenario. In the SCAR
scenario, multiple user agents have a limited supply of a resource that they
either use or collect, depending on the scenario. To enable persistent
autonomy, dedicated replenishment agents travel to the user agents and
replenish or collect their supply of the resource, thus allowing them to
operate indefinitely in the field. Of the two objective functions, one uses a
Monte Carlo method, while the other uses a significantly faster analytical
method. Approximations to multiplication, division and inversion of Gaussian
distributed variables are used to facilitate propagation of probability
distributions in the analytical method when Gaussian distributed parameters are
used. The analytical objective function is shown to have greater than 99%
comparison accuracy when compared with the Monte Carlo objective function while
achieving speed gains of several orders of magnitude.


title:
Stochastic Collection and Replenishment (SCAR) Optimisation for
  Persistent Autonomy

abstract:
  Robots have a finite supply of resources such as fuel, battery charge, and
storage space. The aim of the Stochastic Collection and Replenishment (SCAR)
scenario is to use dedicated agents to refuel, recharge, or otherwise replenish
robots in the field to facilitate persistent autonomy. This paper explores the
optimisation of the SCAR scenario with a single replenishment agent, using
several different objective functions. The problem is framed as a combinatorial
optimisation problem, and A* is used to find the optimal schedule. Through a
computational study, a ratio objective function is shown to have superior
performance compared with a total weighted tardiness objective function, with a
greater performance advantage present when using shorter schedule lengths. The
importance of incorporating uncertainty in the objective function used in the
optimisation process is also highlighted, in particular for scenarios in which
the replenishment agent is under- or fully-utilised.


title: Modified Fermi Energy of Electrons in a Superhigh Magnetic Field

abstract:
  In this paper, we investigate the electron Landau-level stability and its
influence on the electron Fermi energy, $E_{\rm F}(e)$, in the circumstance of
magnetars, which are powered by magnetic field energy. In a magnetar, the
Landau levels of degenerate and relativistic electrons are strongly quantized.
A new quantity $g_{n}$, the electron Landau-level stability coefficient is
introduced. According to the requirement that $g_{n}$ decreases with increasing
the magnetic field intensity $B$, the magnetic-field index $\beta$ in the
expression of $E_{\rm F}(e)$ must be positive. By introducing the
Dirac$-\delta$ function, we deduce a general formulae for the Fermi energy of
degenerate and relativistic electrons, and obtain a particular solution to
$E_{\rm F}(e)$ in a superhigh magnetic field (SMF). This solution has a low
magnetic-field index of $\beta=1/6$, compared with the previous one, and works
when $\rho\geq 10^{7}$~g cm$^{-3}$ and $B_{\rm cr}\ll B\leq 10^{17}$~Gauss. By
modifying the phase space of relativistic electrons, a SMF can enhance the
electron number density $n_e$, and decrease the maximum of electron Landau
level number, which results in a redistribution of electrons. According to
Pauli exclusion principle, the degenerate electrons will fill quantum states
from the lowest Landau level to the highest Landau level. As $B$ increases,
more and more electrons will occupy higher Landau levels, though $g_{n}$
decreases with the Landau level number $n$. The enhanced $n_{e}$ in a SMF means
an increase in the electron Fermi energy and an increase in the electron
degeneracy pressure. The results are expected to facilitate the study of the
weak-interaction processes inside neutron stars and the magnetic-thermal
evolution mechanism for megnetars.


title: Spitzer Observations of Exoplanets Discovered with The Kepler K2 Mission

abstract:
  We have used the {\it Spitzer Space Telescope} to observe two transiting
planetary systems orbiting low mass stars discovered in the \Kepler \Ktwo
mission. The system K2-3 (EPIC 201367065) hosts three planets while EPIC
202083828 (K2-26) hosts a single planet. Observations of all four objects in
these two systems confirm and refine the orbital and physical parameters of the
planets. The refined orbital information and more precise planet radii possible
with \Spitzer will be critical for future observations of these and other \Ktwo
targets. For K2-3b we find marginally significant evidence for a Transit Timing
Variation between the \Ktwo and \Spitzer\ epochs.


title:
Spin ordered ground state and thermodynamic behaviors of the spin-3/2
  kagome Heisenberg antiferromagnet

abstract:
  Three different tensor network optimization algorithms are employed to
accurately determine the ground state and thermodynamic properties of the
spin-3/2 kagome Heisenberg antiferromagnet. We found that the $\sqrt{3} \times
\sqrt{3}$ state, rather than the $q = 0$ state, is the ground state of this
system, and such an ordered state is melted at any finite temperature, thereby
clarifying the existing experimental controversies. A 1/3-magnetization plateau
in the magnetic curve is observed, being consistent with the experimental
observation. The absence of a zero-magnetization plateau indicates a gapless
spin excitation that is further supported by the thermodynamic asymptotic
behaviors of the susceptibility and specific heat. At low temperatures, the
specific heat is shown to exhibit a $\sqrt{T}$ behavior, and the susceptibility
approaches a finite constant as $T\rightarrow 0$. Our TN results of
thermodynamic properties are compared with those from high temperature series
expansion. In addition, we observe a quantum phase transition between $q = 0$
and $\sqrt{3}\times\sqrt{3}$ states in a spin-3/2 kagome XXZ model at the
critical point $\Delta_c = 0.408$. This study provides reliable and useful
information for further explorations on high spin kagome physics.


title: Dipole magnetic field of neutron stars in $f(R)$ gravity

abstract:
  The structure of an interior dipole magnetic field of neutron stars in $f(R)$
gravity is considered. For this purpose, the perturbative approaches are used
when both the deviations from general relativity and the deformations of
spherically symmetric configurations associated with the presence of the
magnetic field are assumed to be small. Solutions are constructed which
describe relativistic, spherically symmetric configurations consisting of a
gravitating magnetized perfect fluid modeled by a realistic equation of state.
Comparing configurations from general relativity and modified gravity, we
reveal possible differences in the structure of the magnetic field which occur
in considering neutron stars in modified gravity.


title:
B-spline quasi-interpolation sampling representation and sampling
  recovery in Sobolev spaces of mixed smoothness

abstract:
  We proved direct and inverse theorems on B-spline quasi-interpolation
sampling representation with a Littlewood-Paley-type norm equivalence in
Sobolev spaces $W^r_p$ of mixed smoothness $r$, established estimates of the
approximation error of recovery in $L_q$-norm of functions from the unit ball
$U^r_p$ in the spaces $W^r_p$ by linear sampling algorithms based on this
representation, the asymptotic optimality of these sampling algorithms in terms
of Smolyak sampling width $r^s_n(U^r_p, L_q)$ and sampling width $r_n(U^r_p,
L_q)$.


title:
Formation, Evolution, and Revolution of Galaxies by SKA: Activities of
  SKA-Japan Galaxy Evolution Sub-SWG

abstract:
  Formation and evolution of galaxies have been a central driving force in the
studies of galaxies and cosmology. Recent studies provided a global picture of
cosmic star formation history. However, what drives the evolution of star
formation activities in galaxies has long been a matter of debate. The key
factor of the star formation is the transition of hydrogen from atomic to
molecular state, since the star formation is associated with the molecular
phase. This transition is also strongly coupled with chemical evolution,
because dust grains, i.e., tiny solid particles of heavy elements, play a
critical role in molecular formation. Therefore, a comprehensive understanding
of neutral-molecular gas transition, star formation and chemical enrichment is
necessary to clarify the galaxy formation and evolution. Here we present the
activity of SKA-JP galaxy evolution sub-science working group (subSWG) Our
activity is focused on three epochs: z \sim 0, 1, and z > 3. At z \sim 0, we
try to construct a unified picture of atomic and molecular hydrogen through
nearby galaxies in terms of metallicity and other various ISM properties. Up to
intermediate redshifts z \sim 1, we explore scaling relations including gas and
star formation properties, like the main sequence and the Kennicutt-Schmidt law
of star forming galaxies. To connect the global studies with spatially-resolved
investigations, such relations will be plausibly a viable way. For high
redshift objects, the absorption lines of HI 21-cm line will be a very
promising observable to explore the properties of gas in galaxies. By these
studies, we will surely witness a real revolution in the studies of galaxies by
SKA.


title: A graph theoretic approach for modelling wildlife corridors

abstract:
  Wildlife corridors are components of landscapes, which facilitate the
movement of organisms and processes between areas of intact habitat, and thus
provide landscape corridor. Corridors are thus regions within a given landscape
that generally comprise native vegetation, and connect otherwise fragmented,
disconnected, non-contiguous wildlife habitat patches in the landscape. The
purpose of designing corridors as a conservation strategy is primarily to
counter, and to the extent possible, mitigate the impacts of habitat
fragmentation and loss on the biodiversity of the landscape, as well as support
continuance of land use for essential local and global economic activities in
the region of reference. In this paper, we use game theory and graph theory to
model and design a wildlife corridor network in the Central India Eastern Ghats
landscape complex, with tiger (Panthera tigris tigris) as the focal species. We
construct a graph using the habitat patches supporting wild tiger populations
in the landscape complex as vertices and the possible paths between these
vertices as edges. A cost matrix is constructed to indicate the cost incurred
by the tiger for passage between the habitat patches in the landscape, by
modelling a two-person Prisoners Dilemma game. A minimum spanning tree is then
obtained by employing Kruskals algorithm, which would suggest a feasible tiger
corridor network for the tiger population within the landscape complex.
Additionally, analysis of the graph is done using various centrality measures,
in order to identify and focus on potentially important habitat patches, and
their potential community structure. Correlation analysis is performed on the
centrality indices to draw out interesting trends in the network.


title: Unconventional optical microcavities hosting multiple exceptional points

abstract:
  Recently, presence of hidden singularities known as exceptional points (EPs)
in non-Hermitian quantum systems has opened up a tremendous interest in
different domains of physics owing to their unique unconventional physical
effects. Effectively for such systems an EP appears as a fascinating
topological defect where two mutually interacting eigenstates of the system
coalesce. In this work, we report occurrence of EP via avoided crossing between
coupled resonance states in an optical microcavity with spatially varying gain
loss profile, an optical analogue of non-Hermitian system. With suitably
tailored system openness and coupling strength, internally coupled resonances
can exhibit EP in a medium with simultaneous presence of loss and gain. We
explore the characteristics behaviors of energy eigenvalues in complex energy
plane and corresponding eigenstates when the control parameters of the system
are adiabatically changed, such a way that they encircle the EP. In this
letter, we first ever exploit the above scheme to analyze the optical
performance in terms of stability and rigidity of a microcavity simultaneously
hosting such multiple EPs.


title:
Density Functional Theory based Study of Chlorine Doped WS2-metal
  Interface

abstract:
  Investigation of a TMD-metal interface is essential for the effective
functioning of monolayer TMD based field effect transistors (FETs). In this
work, we employ Density Functional Theory (DFT) calculations to analyze the
modulation of the electronic structure of monolayer WS2 with chlorine doping
and the relative changes in the contact properties when interfaced with gold
and palladium. We initially examine the atomic and electronic structures of
pure and doped monolayer WS2 supercell and explore the formation of mid gap
states with band splitting near the conduction band edge. Further we analyze
the contact nature of the pure supercell with Au and Pd. We find that while Au
is physiosorped and forms n-type contact, Pd is chemisorped and forms p-type
contact with a higher valence electron density. Next, we study the interface
formed between the Cl-doped supercell and metals and observe a reduction in the
Schottky barrier height (SBH) in comparison to the pure supercell. This
reduction found is higher for Pd in comparison to Au which is further validated
by examining the charge transfer occurring at the interface. Our study confirms
that Cl doping is an efficient mechanism to reduce the n-SBH for both Au and Pd
which form different types of contact with WS2.


title: A Two-Stage Shape Retrieval (TSR) Method with Global and Local Features

abstract:
  A robust two-stage shape retrieval (TSR) method is proposed to address the 2D
shape retrieval problem. Most state-of-the-art shape retrieval methods are
based on local features matching and ranking. Their retrieval performance is
not robust since they may retrieve globally dissimilar shapes in high ranks. To
overcome this challenge, we decompose the decision process into two stages. In
the first irrelevant cluster filtering (ICF) stage, we consider both global and
local features and use them to predict the relevance of gallery shapes with
respect to the query. Irrelevant shapes are removed from the candidate shape
set. After that, a local-features-based matching and ranking (LMR) method
follows in the second stage. We apply the proposed TSR system to MPEG-7,
Kimia99 and Tari1000 three datasets and show that it outperforms all other
existing methods. The robust retrieval performance of the TSR system is
demonstrated.


title:
Partially Block Markov Superposition Transmission of Gaussian Source
  with Nested Lattice Codes

abstract:
  This paper studies the transmission of Gaussian sources through additive
white Gaussian noise (AWGN) channels in bandwidth expansion regime, i.e., the
channel bandwidth is greater than the source bandwidth. To mitigate the error
propagation phenomenon of conventional digital transmission schemes, we propose
in this paper a new capacity-approaching joint source channel coding (JSCC)
scheme based on partially block Markov superposition transmission (BMST) of
nested lattice codes. In the proposed scheme, first, the Gaussian source
sequence is discretized by a lattice-based quantizer, resulting in a sequence
of lattice points. Second, these lattice points are encoded by a short
systematic group code. Third, the coded sequence is partitioned into blocks of
equal length and then transmitted in the BMST manner. Main characteristics of
the proposed JSCC scheme include: 1) Entropy coding is not used explicitly. 2)
Only parity-check sequence is superimposed, hence, termed partially BMST
(PBMST). This is different from the original BMST. To show the superior
performance of the proposed scheme, we present extensive simulation results
which show that the proposed scheme performs within 1.0 dB of the Shannon
limits. Hence, the proposed scheme provides an attractive candidate for
transmission of Gaussian sources.


title:
A note on small periodic solutions of discrete nonlinear Klein-Gordon
  equations

abstract:
  In this note, we consider discrete nonlinear Klein-Gordon equations with
potential. By the pioneering work of Sigal, it is known that for the
"continuous" nonlinear Klein-Gordon equation, no small time periodic solution
exists generically. However, for the discrete nonlinear Klein-Gordon equations,
we show that there exist small time periodic solutions.


title:
Feedback control: two-sided Markov-modulated Brownian motion with
  instantaneous change of phase at boundaries

abstract:
  We consider a Markov-modulated Brownian motion $\{Y(t), \rho(t)\}$ with two
boundaries at $0$ and $b > 0$, and allow for the controlling Markov chain
$\{\rho(t)\}$ to instantaneously undergo a change of phase upon hitting either
of the two boundaries at semi-regenerative epochs defined to be the first time
the process reaches a boundary since it last hits the other boundary. We call
this process a flexible Markov-modulated Brownian motion.
  Using the recently-established links between stochastic fluid models and
Markov-modulated Brownian motions, we determine important characteristics of
first exit times of a Markov-modulated Brownian motion from an interval with a
regulated boundary. These results allow us to follow a Markov-regenerative
approach and obtain the stationary distribution of the flexible process. This
highlights the effectiveness of the regenerative approach in analyzing
Markov-modulated Brownian motions subject to more general boundary behaviors
than the classic regulated boundaries.


title:
Spin-orbit coupled correlated metal phase in Kondo lattices: an
  implementation with alkaline-earth atoms

abstract:
  We show that an interplay between quantum effects, strong on-site
ferromagnetic exchange interaction and antiferromagnetic correlations in Kondo
lattices can give rise to an exotic spin-orbit coupled metallic state in
regimes where classical treatments predict a trivial insulating behavior. This
phenomenon can be simulated with ultracold alkaline-earth fermionic atoms
subject to a laser-induced magnetic field by observing dynamics of spin-charge
excitations in quench experiments.


title:
Energy transfer model for the derivative nonlinear Schrodinger equations
  on the torus

abstract:
  We consider the nonlinear derivative Schrodinger equation with a quintic
nonlinearity, on the one dimensional torus. We exhibit that the nonlinear
dynamic properties consist of four frequency modes initially excited, whose
frequencies include the resonant clusters and phase matched resonant
interactions of nonlinearities. This phenomena arrests energy transfers between
low and high modes, which are quantified by a growth in the Sobolev norm.


title: Dynamical angled brane

abstract:
  We discuss the dynamical D$p$-brane solutions describing any number of
D$p$-branes whose relative orientations are given by certain SU(2) rotations.
These are the generalization of the static angled D$p$-brane solutions. We
study the collision of dynamical D3-brane with angles in type II string theory,
and show that the particular orientation of the smeared D3-brane configuration
can provide an example of colliding branes if they have the same charges.
Otherwise a singularity appears before D3-branes collide.


title:
An explicit prime geodesic theorem for discrete tori and the
  hypergeometric functions

abstract:
  The discrete tori are graph analogues of the real tori, which are defined by
the Cayley graphs of a finite product of finite cyclic groups. In this paper,
using the theory of the heat kernel on the discrete tori established by Chinta,
Jorgenson and Karlsson, we derive an explicit prime geodesic theorem for the
discrete tori, which is not an asymptotic formula. To describe the formula, we
need generalizations of the classical Jacobi polynomials, which are defined by
the Lauricella multivariable hypergeometric function of type C.


title:
Possible role of magnetic reconnection in the electromagnetic
  counterpart of binary black hole merger

abstract:
  We propose a qualitative scenario to interpret the argued association between
the direct measurement of the gravitational wave event GW150914 by Laser
Interferometer Gravitational Wave Observatory (LIGO)-Virgo collaborations and
the hard $X$-ray transient detected by Fermi-Gamma-ray Burst Monitor (GBM)
$0.4$ sec after. In a binary system of two gravitationally collapsing objects
with a non-vanishing electric charge, the compenetration of the two
magnetospheres occurring during the coalescence, through magnetic reconnection,
produces a highly collimated relativistic outflow that becomes optically thin
and shines in the GBM field of view. We propose that this process should be
expected as a commonplace in the future joint gravitational/electromagnetic
detections and, in case of neutron star-neutron star merger event, might lead
to detectable $X$- or $\gamma$-ray precursors to, or transients associated
with, the gravitational bursts.

categories: astro-ph.HE astro-ph.CO gr-qc physics.plasm-ph


title: SKA-Japan Pulsar Science with the Square Kilometre Array

abstract:
  The Square Kilometre Array will revolutionize pulsar studies with its wide
field-of-view, wide-band observation and high sensitivity, increasing the
number of observable pulsars by more than an order of magnitude. Pulsars are of
interest not only for the study of neutron stars themselves but for their usage
as tools for probing fundamental physics such as general relativity,
gravitational waves and nuclear interaction. In this article, we summarize the
activity and interests of SKA-Japan Pulsar Science Working Group, focusing on
an investigation of modified gravity theory with the supermassive black hole in
the Galactic Centre, gravitational-wave detection from cosmic strings and
binary supermassive black holes, a study of the physical state of plasma close
to pulsars using giant radio pulses and determination of magnetic field
structure of Galaxy with pulsar pairs.


title: Estimating transport coefficients in hot and dense quark matter

abstract:
  We compute the transport coefficients, namely, the coefficients of shear and
bulk viscosity as well as thermal conductivity for hot and dense quark matter.
The calculations are performed within the Nambu- Jona Lasinio (NJL) model. The
estimation of the transport coefficients is made using a quasiparticle approach
of solving the Boltzmann kinetic equation within the relaxation time
approximation. The transition rates are calculated in a manifestly covariant
manner to estimate the thermal-averaged cross sections for quark-quark and
quark-antiquark scattering. The calculations are performed for finite chemical
potential also. Within the parameters of the model, the ratio of shear
viscosity to entropy density has a minimum at the Mott transition temperature.
At vanishing chemical potential, the ratio of bulk viscosity to entropy
density, on the other hand, decreases with temperature with a sharp decrease
near the critical temperature, and vanishes beyond it. At finite chemical
potential, however, it increases slowly with temperature beyond the Mott
temperature. The coefficient of thermal conductivity also shows a minimum at
the critical temperature.


title:
The effect of a wider initial separation on common envelope binary
  interaction simulations

abstract:
  We present hydrodynamic simulations of the common envelope binary interaction
between a giant star and a compact companion carried out with the adaptive mesh
refinement code ENZO and the smooth particle hydrodynamics code PHANTOM. These
simulations mimic the parameters of one of the simulations by Passy et al., but
assess the impact of a larger, more realistic initial orbital separation on the
simulation outcome. We conclude that for both codes the post-common envelope
separation is somewhat larger and the amount of unbound mass slightly greater
when the initial separation is wide enough that the giant does not yet overflow
or just overflows its Roche lobe. PHANTOM has been adapted to the common
envelope problem here for the first time and a full comparison with ENZO is
presented, including an investigation of convergence as well as energy and
angular momentum conservation. We also set our simulations in the context of
past simulations. This comparison reveals that it is the expansion of the giant
before rapid in-spiral and not spinning up of the star that causes a larger
final separation. We also suggest that the large range in unbound mass for
different simulations is difficult to explain and may have something to do with
simulations that are not fully converged.


title:
A Real-Time and Energy-Efficient Implementation of
  Difference-of-Gaussian with Flexible Thin-Film Transistors

abstract:
  With many advantageous features, softness and better biocompatibility,
flexible electronic devices have developed rapidly and increasingly attracted
attention. Many currently applications with flexible devices are sensors and
drivers, while there is nearly no utilization aiming at complex computation
since flexible devices have lower electron mobility, simple structure and large
process variation. In this paper, we proposed an innovative method that enabled
flexible devices to implement real-time and energy-efficient
Difference-of-Gaussian, which illustrated feasibility and potentials for them
to achieve complicated real-time computation in future generation products.


title:
Numerical modelling of microchannel gas flows in the transition flow
  regime using the cascaded lattice Boltzmann method

abstract:
  In the CLB method, a Bosanquet-type effective viscosity is employed to
account for the rarefaction effect on the gas viscosity. To gain accurate
simulations and to match the Bosanquet-type effective viscosity, the combined
bounce-back/specular-reflection boundary scheme with a modified second-order
slip boundary condition is adopted in the CLB method. The present method is
applied to study gas flow in a microchannel with periodic boundary condition
and gas flow in a long microchannel (the ratio of the length to the height
L/H=100) with pressure boundary condition over a wide range of Knudsen numbers.
The influence of the rarefaction effect on the velocity profile, the mass flow
rate, and the non-linear pressure deviation distribution along the long
microchannel are investigated.


title: Ball Convex Bodies in Minkowski Spaces

abstract:
  The notion of ball convexity, considered in finite dimensional real Banach
spaces, is a natural and useful extension of usual convexity; one replaces
intersections of half-spaces by suitable intersections of balls. A subset $S$
of a normed space is called ball convex if it coincides with its ball hull,
which is obtained as intersection of all balls (of fixed radius) containing
$S$. Ball convex sets are closely related to notions like ball polytopes,
complete sets, bodies of constant width, and spindle convexity. We will study
geometric properties of ball convex bodies in normed spaces, for example
deriving separation theorems, characterizations of strictly convex norms, and
an application to complete sets. Our main results refer to minimal
representations of ball convex bodies in terms of their ball exposed faces, to
representations of ball hulls of sets via unions of ball hulls of finite
subsets, and to ball convexity of increasing unions of ball convex bodies.


title: Prediction of a Two-dimensional Phosphorus Nitride Monolayer

abstract:
  Today, 2D semiconductor materials have been extended into the nitrogen group:
phosphorene, arsenene, antimonene and even nitrogene. Motivated by them, based
upon first-principles density functional calculations, we propose a new
two-dimensional phosphorus nitride (PN) structure that is stable well above the
room temperature, due to its extremely high cohesive energy. Unlike
phosphorene, PN structure is resistant to high temperature oxidation. The
structure is predicted to be a semiconductor with a wide, indirect band gap of
2.64 eV. More interestingly, the phosphorus nitride monolayer experiences an
indirect-to-direct band-gap transition at a relatively small tensile strain.
Such dramatic transformation in the electronic structure combined with
structural stability and oxidation resistance at high temperature could pave
the way for exciting innovations in high-speed ultrathin transistors, power
electronic modules, ultra-high efficiency LEDs and semiconductor lasers.


title: A Unified View of Quantum Correlations and Quantum Coherence

abstract:
  In this paper, we argue that quantum coherence in a bipartite system can be
contained either locally or in the correlations between the subsystems. The
portion of quantum coherence contained within correlations can be viewed as a
kind quantum correlation which we call correlated coherence. We demonstrate
that the framework provided by correlated coherence allows us retrieve the same
concepts of quantum correlations as defined by the asymmetric and symmetrized
versions of quantum discord as well as quantum entanglement, thus providing a
unified view of these correlations. We also prove that correlated coherence can
be formulated as an entanglement monotone, thus demonstrating that entanglement
may be viewed as a specialized form of coherence.


title: Cosmology with the Square Kilometre Array by SKA-Japan

abstract:
  In the past several decades, the standard cosmological model has been
established and its parameters have been measured to a high precision, while
there are still many of the fundamental questions in cosmology; such as the
physics in the very early Universe, the origin of the cosmic acceleration and
the nature of the dark matter. The future world's largest radio telescope,
Square Kilometre Array (SKA), will be able to open the new frontier of
cosmology and will be one of the most powerful tools for cosmology in the next
decade. The cosmological surveys conducted by the SKA would have the potential
not only to answer these fundamental questions but also deliver the precision
cosmology. In this article we briefly review the role of the SKA from the view
point of the modern cosmology. The cosmology science led by the SKA-Japan
Consortium (SKA-JP) Cosmology Science Working Group is also discussed.


title: Multiplicity of critical points for the fractional Allen-Cahn energy

abstract:
  In this paper we study the fractional analogue of the Allen-Cahn energy in
bounded domains, and we show that it admits a number of critical points which
goes to infinity as the perturbation parameter tends to zero.


title:
Japanese Cosmic Dawn/Epoch of Reionization Science with the Square
  Kilometre Array

abstract:
  Cosmic reionization is known to be a major phase transition of the gas in the
Universe. Since astronomical objects formed in the early Universe, such as the
first stars, galaxies and black holes, are expected to have caused cosmic
reionization, the formation history and properties of such objects are closely
related to the reionization process. In spite of the importance of exploring
reionization, our understandings regarding reionization is not sufficient yet.
Square Kilometre Array (SKA) is a next-generation large telescope that will be
operated in the next decade. Although several programs of next-generation
telescopes are currently scheduled, the SKA will be the unique telescope with a
potential to directly observe neutral hydrogen up to z~30, and provide us with
valuable information on the Cosmic Dawn (CD) and the Epoch of Reionization
(EoR). The early science with the SKA will start in a few years; it is thus the
time for us to elaborate a strategy for CD/EoR Science with the SKA. The
purpose of this document is to introduce Japanese scientific interests in the
SKA project and to report results of our investigation.


title:
Muon Spin Relaxation and Neutron Diffraction Studies of Cluster-Glass
  States in Sr1-xLaxRuO3

abstract:
  To clarify the magnetic properties of cluster-glass states in Sr1-xLaxRuO3
(0.3 <= x <= 0.5), we report herein the results of muon spin relaxation (muSR)
and neutron powder diffraction measurements. The muSR experiments showed that
magnetic clusters start developing well above the peak temperature T^* in the
ac susceptibility. The volume fraction of the magnetically ordered region
increases continuously with decreasing temperature, showing no anomaly at T^*,
and reaches nearly 100% at the lowest temperature. The temperature variation of
the volume fraction is essentially independent of the La concentration in the x
range presently investigated, although the dc magnetization is significantly
suppressed with increasing x. Neutron powder diffraction experiments revealed
that the ground state for x = 0.3 is a long-range ferromagnetic ordered state.
These results indicate that, with decreasing temperature, cluster-glass states
in Sr1-xLaxRuO3 gradually develop into long-range ferromagnetic ordered states
with decreasing temperature, and that the magnetic ordering process differs
strikingly from that expected for a conventional second-order ferromagnetic
transition.


title:
Discrete-time analysis for the integrable discrete Toda equations and
  the discrete Lotka-Volterra system

abstract:
  The discrete autonomous/non-autonomous Toda equations and the discrete
Lotka-Volterra system are important integrable discrete systems in fields such
as mathematical physics, mathematical biology and statistical physics. They
also have applications to numerical linear algebra. In this paper, we first
simultaneously obtain their general solutions. Then, we show the asymptotic
behavior of the solutions for any initial values as the discrete-time variables
go to infinity. Our two main techniques for understanding the distinct
integrable systems are to introduce two types of discrete-time variables and to
examine properties of a restricted infinite sequence, its associated
determinants and polynomials.