title:
Hybrid-DCA: A Double Asynchronous Approach for Stochastic Dual
  Coordinate Ascent

abstract:
  In prior works, stochastic dual coordinate ascent (SDCA) has been
parallelized in a multi-core environment where the cores communicate through
shared memory, or in a multi-processor distributed memory environment where the
processors communicate through message passing. In this paper, we propose a
hybrid SDCA framework for multi-core clusters, the most common high performance
computing environment that consists of multiple nodes each having multiple
cores and its own shared memory. We distribute data across nodes where each
node solves a local problem in an asynchronous parallel fashion on its cores,
and then the local updates are aggregated via an asynchronous across-node
update scheme. The proposed double asynchronous method converges to a global
solution for $L$-Lipschitz continuous loss functions, and at a linear
convergence rate if a smooth convex loss function is used. Extensive empirical
comparison has shown that our algorithm scales better than the best known
shared-memory methods and runs faster than previous distributed-memory methods.
Big datasets, such as one of 280 GB from the LIBSVM repository, cannot be
accommodated on a single node and hence cannot be solved by a parallel
algorithm. For such a dataset, our hybrid algorithm takes 30 seconds to achieve
a duality gap of $10^{-6}$ on 16 nodes each using 8 cores, which is
significantly faster than the best known distributed algorithms, such as
CoCoA+, that take more than 300 seconds on 16 nodes.


title: Pedestrians rotation measurement in bidirectional streams

abstract:
  This study presents an experimental measurement of pedestrians' body rotation
in bidirectional streams. A mock-up corridor monitored using a camera placed on
azimuthal position is used to study pedestrians' behavior in unidirectional and
bidirectional flows. Additionally, a commercial tablet is fixed on the chest of
sample pedestrians to examine their body rotation (or yawing) which cannot be
obtained using position tracking alone. Angular velocity is recorded and
simultaneously stored in a central location using a wireless network, thus
allowing the analysis of body movements with a high sampling rate and a limited
delay. To investigate the influence of major/minor flow proportion (flow-ratio)
on bidirectional streams two different situations were tested: the balanced
configuration (with equal flows in both directions) and an unbalanced
configuration (with different major and minor flow). Results clearly show that
unidirectional flow is more stable compared to the bidirectional case,
requiring less time to cross the experimental section and showing a very small
amount of rotation during the whole experiment. Both bidirectional
configurations showed high values of body rotation, in particular during lane
formation and dissolution. Finally, rotation directly measured on pedestrians'
body was compared with the one obtained indirectly by analyzing pedestrians'
trajectories. The comparison shows that, at least from a qualitative point of
view, both methods are in agreement, thus suggesting that even properties which
can only be measured by motion sensing could be obtained indirectly through the
analysis of trajectories. Concluding, it has been suggested that while lanes
help smooth out bidirectional flows, larger instabilities are observed compared
to the unidirectional case. Lane separation and/or appropriate guidance are
therefore required.


title:
The A-B transition in superfluid 3He under confinement in a thin slab
  geometry

abstract:
  The influence of confinement on the topological phases of superfluid 3He is
studied using the torsional pendulum method. We focus on the phase transition
between the chiral A-phase and the time-reversal-invariant B-phase, motivated
by the prediction of a spatiallymodulated (stripe) phase at the A-B phase
boundary. We confine superfluid 3He to a single 1.08 {\mu}m thick nanofluidic
cavity incorporated into a high-precision torsion pendulum, and map the phase
diagram between 0.1 and 5.6 bar. We observe only small supercooling of the
A-phase, in comparison to bulk or when confined in aerogel. This has a
non-monotonic pressure dependence, suggesting that a new intrinsic B-phase
nucleation mechanism operates under confinement, mediated by the putative
stripe phase. Both the phase diagram and the relative superfluid fraction of
the A and B phases, show that strong coupling is present at all pressures, with
implications for the stability of the stripe phase.


title:
Learning Deep Architectures for Interaction Prediction in
  Structure-based Virtual Screening

abstract:
  We introduce a deep learning architecture for structure-based virtual
screening that generates fixed-sized fingerprints of proteins and small
molecules by applying learnable atom convolution and softmax operations to each
compound separately. These fingerprints are further transformed non-linearly,
their inner-product is calculated and used to predict the binding potential.
Moreover, we show that widely used benchmark datasets may be insufficient for
testing structure-based virtual screening methods that utilize machine
learning. Therefore, we introduce a new benchmark dataset, which we constructed
based on DUD-E and PDBBind databases.


title: Be Stars Seen by Space Photometry

abstract:
  Classical Be stars are introduced as object class and their particular
potential for space based photometry is highlighted. A brief summary of the
various types of variability observed in Be stars makes clear that an
interpretation of every single frequency as a pulsation mode falls short,
instead there are as well purely circumstellar variations and those that
originate in the immediate stellar to circumstellar interaction region. In
particular the latter offer great potential, as they are linked to one of the
few remaining great riddles of Be stars, namely how they feed their disks.


title:
Gupta-Bleuler's quantization of a parity-odd CPT-even electrodynamics of
  the standard model extension

abstract:
  {Following a successfully quantization scheme previously }{{% developed {\ in
Ref. \cite{GUPTAEVEN} for a}} parity-even {gauge sector} {of the SME, we}} have
established the Gupta-Bleuler {% quantization {of a} {\ parity-odd} and
CPT-even }electrodynamics of {the }standard model extension (SME) {without
recoursing to a small photon mass regulator}. {Keeping the photons massless,}
{% {we have adopted the gauge fixing condition:}} $G(A_{\mu })=(\partial
_{0}+\kappa^{0j}\partial _{j}) (A_{0}+\kappa ^{0k}A_{k})+\partial _{i}A^{i}$% .
The{\ four} polarization vectors of the gauge field are {% exactly} determined
by solving an eigenvalue problem,{\ exhibiting birefringent second order
contributions in the Lorentz-violating parameters}% . They allow to express the
Hamiltonian in terms of annihilation and creation operators whose positivity is
guaranteed by imposing a weak Gupta-Bleuler constraint, defining the physical
states. Consequently, we compute the field commutation relation which has been
expressed in terms of Pauli-Jordan functions modified by Lorentz violation
whose light-cone structures have allowed to analyze the microcausality issue.


title:
The Security of Hardware-Based Omega(n^2) Cryptographic One-Way
  Functions: Beyond Satisfiability and P=NP

abstract:
  We present a class of hardware-based cryptographic one-way functions that, in
practice, would be hard to invert even if P=NP and linear-time satisfiability
algorithms exist. Such functions use a hardware-based component with omega(n^2)
size circuits, and omega(n^2) run time.


title:
A New Measurement of the Spectral Lag of Gamma-Ray Bursts and its
  Implications for Spectral Evolution Behaviors

abstract:
  We carry out a systematical study of the spectral lag properties of 50
single-pulsed Gamma-Ray Bursts (GRBs) detected by Fermi/GBM. By dividing the
light curves into multiple consecutive energy channels we provide a new
measurement of the spectral lag which is independent on energy channel
selections. We perform a detailed statistical study of our new measurements. We
find two similar power-law energy dependencies of both the pulse arrival time
and pulse width. Our new results on the power-law indices would favor the
relativistic geometric effects for the origin of spectral lag. However, a
complete theoretical framework that can fully account for the diverse energy
dependencies of both arrival time and pulse width revealed in this work is
still missing. We also study the spectral evolution behaviors of the GRB
pulses. We find that the GRB pulse with negligible spectral lag would usually
have a shorter pulse duration and would appear to have a "hardness-intensity
tracking" (HIT) behavior and the GRB pulse with a significant spectral lag
would usually have a longer pulse duration and would appear to have a
"hard-to-soft" (HTS) behavior.


title: Twin Supergravities from Yang-Mills Squared

abstract:
  We consider `twin supergravities' - pairs of supergravities with
$\mathcal{N}_+$ and $\mathcal{N}_-$ supersymmetries,
$\mathcal{N}_+>\mathcal{N}_-$, with identical bosonic sectors - in the context
of tensoring super Yang-Mills multiplets. It is demonstrated that the pairs of
twin supergravity theories are related through their left and right super
Yang-Mills factors. This procedure generates new theories from old. In
particular, the matter coupled $\mathcal{N}_-$ twins in $D=3,5,6$ and the
$\mathcal{N}_-=1$ twins in $D=4$ have not, as far as we are aware, been
obtained previously using the double-copy construction, adding to the growing
list of double-copy constructible theories. The use of fundamental matter
multiplets in the double-copy construction leads us to introduce a
bi-fundamental scalar that couples to the well-known bi-adjoint scalar field.
It is also shown that certain matter coupled supergravities admit more than one
factorisation into left and right super Yang-Mills-matter theories.


title: Simpler PAC-Bayesian Bounds for Hostile Data

abstract:
  PAC-Bayesian learning bounds are of the utmost interest to the learning
community. Their role is to connect the generalization ability of an
aggregation distribution $\rho$ to its empirical risk and to its
Kullback-Leibler divergence with respect to some prior distribution $\pi$.
Unfortunately, most of the available bounds typically rely on heavy assumptions
such as boundedness and independence of the observations. This paper aims at
relaxing these constraints and provides PAC-Bayesian learning bounds that hold
for dependent, heavy-tailed observations (hereafter referred to as
\emph{hostile data}). In these bounds the Kullack-Leibler divergence is
replaced with a general version of Csisz\'ar's $f$-divergence. We prove a
general PAC-Bayesian bound, and show how to use it in various hostile settings.


title:
Asymptotics for the fractional Allen-Cahn equation and stationary
  nonlocal minimal surfaces

abstract:
  This article is mainly devoted to the asymptotic analysis of a fractional
version of the (elliptic) Allen-Cahn equation in a bounded domain
$\Omega\subset\mathbb{R}^n$, with or without a source term in the right hand
side of the equation (commonly called chemical potential). Compare to the usual
Allen-Cahn equation, the Laplace operator is here replaced by the fractional
Laplacian $(-\Delta)^s$ with $s\in(0,1/2)$, as defined in Fourier space. In the
singular limit $\varepsilon\to 0$, we show that arbitrary solutions with
uniformly bounded energy converge both in the energetic and geometric sense to
surfaces of prescribed nonlocal mean curvature in $\Omega$ whenever the
chemical potential remains bounded in suitable Sobolev spaces. With no chemical
potential, the notion of surface of prescribed nonlocal mean curvature reduces
to the stationary version of the nonlocal minimal surfaces introduced by L.A.
Caffarelli, J.M. Roquejoffre, and O. Savin. Under the same Sobolev regularity
assumption on the chemical potential, we also prove that surfaces of prescribed
nonlocal mean curvature have a Minkowski codimension equal to one, and that the
associated sets have a locally finite fractional $2s^\prime$-perimeter in
$\Omega$ for every $s^\prime\in(0,1/2)$.


title:
Real loci in (log-) Calabi-Yau manifolds via Kato-Nakayama spaces of
  toric degenerations

abstract:
  We study the real loci of toric degenerations of complex varieties with
reducible central fibre. We show that the topology of such degenerations can be
explicitly described via the Kato-Nakayama space of the central fibre as a log
space. We furthermore provide generalities of real structures in log geometry
and their lift to Kato-Nakayama spaces. A key point of this paper is a
description of the Kato-Nakayama space of a toric degeneration and its real
locus, both as bundles determined by combinatorial data. We provide several
examples including real toric degenerations of K3-surfaces and a toric
degeneration of local $\textbb{P}^2$.


title:
Graphene-WS$_2$ heterostructures for tunable spin injection and spin
  transport

abstract:
  We report the first measurements of spin injection in to graphene through a
20 nm thick tungsten disulphide (WS$_2$) layer, along with a modified spin
relaxation time ({\tau}s) in graphene in the WS$_2$ environment, via spin-valve
and Hanle spin-precession measurements, respectively. First, during the
spin-injection into graphene through a WS$_2$-graphene interface, we can tune
the interface resistance at different current bias and modify the spin
injection efficiency, in a correlation with the conductivity-mismatch theory.
Temperature assisted tunneling is identified as a dominant mechanism for the
charge transport across the interface. Second, we measure the spin transport in
graphene, underneath the WS$_2$ crystal and observe a significant reduction in
the {\tau}s down to 17 ps in graphene in the WS$_2$ covered region, compared to
that in its pristine state. The reduced {\tau}s indicates the WS$_2$-proximity
induced additional dephasing of the spins in graphene.


title:
Imaging electronic states on topological semimetals using scanning
  tunneling microscopy

abstract:
  Following the intense studies on topological insulators, significant efforts
have recently been devoted to the search for gapless topological systems. These
materials not only broaden the topological classification of matter but also
provide a condensed matter realization of various relativistic particles and
phenomena previously discussed mainly in high energy physics. Weyl semimetals
host massless, chiral, low-energy excitations in the bulk electronic band
structure, whereas a symmetry protected pair of Weyl fermions gives rise to
massless Dirac fermions. We employed scanning tunneling microscopy/spectroscopy
to explore the behavior of electronic states both on the surface and in the
bulk of topological semimetal phases. By mapping the quasiparticle interference
and emerging Landau levels at high magnetic field in Dirac semimetals
Cd$_3$As$_2$ and Na$_3$Bi, we observed extended Dirac-like bulk electronic
bands. Quasiparticle interference imaged on Weyl semimetal TaAs demonstrated
the predicted momentum dependent delocalization of Fermi arc surface states in
the vicinity of the surface-projected Weyl nodes.


title: A Language-theoretic View on Network Protocols

abstract:
  Input validation is the first line of defense against malformed or malicious
inputs. It is therefore critical that the validator (which is often part of the
parser) is free of bugs.
  To build dependable input validators, we propose using parser generators for
context-free languages. In the context of network protocols, various works have
pointed at context-free languages as falling short to specify precisely or
concisely common idioms found in protocols. We review those assessments and
perform a rigorous, language-theoretic analysis of several common protocol
idioms. We then demonstrate the practical value of our findings by developing a
modular, robust, and efficient input validator for HTTP relying on context-free
grammars and regular expressions.


title: On the general solution of the Heideman-Hogan family of recurrences

abstract:
  We consider a family of nonlinear rational recurrences of odd order which was
introduced by Heideman and Hogan. All of these recurrences have the Laurent
property, implying that for a particular choice of initial data (all initial
values set to 1) they generate an integer sequence. For these particular
sequences, Heideman and Hogan gave a direct proof of integrality by showing
that the terms of the sequence also satisfy a linear recurrence relation with
constant coefficients. Here we present an analogous result for the general
solution of each of these recurrences.


title:
Distinguishing number and distinguishing index of Kronecker product of
  two graphs

abstract:
  The distinguishing number (index) $D(G)$ ($D'(G)$) of a graph $G$ is the
least integer $d$ such that $G$ has an vertex labeling (edge labeling) with $d$
labels that is preserved only by a trivial automorphism. The Kronecker product
$G\times H$ of two graphs $G$ and $H$ is the graph with vertex set $V (G)\times
V (H)$ and edge set $\{\{(u, x), (v, y)\} | \{u, v\} \in E(G) ~and ~\{x, y\}
\in E(H)\}$. In this paper we study the distinguishing number and the
distinguishing index of Kronecker product of two graphs.


title: On the dynamic consistency of hierarchical risk-averse decision problems

abstract:
  In this paper, we consider a risk-averse decision problem for
controlled-diffusion processes, with dynamic risk measures, in which there are
two risk-averse decision makers (i.e., {\it leader} and {\it follower}) with
different risk-averse related responsibilities and information. Moreover, we
assume that there are two objectives that these decision makers are expected to
achieve. That is, the first objective being of {\it stochastic controllability}
type that describes an acceptable risk-exposure set vis-\'a-vis some uncertain
future payoff, and while the {\it second one} is making sure the solution of a
certain risk-related system equation has to stay always above a given
continuous stochastic process, namely {\it obstacle}. In particular, we
introduce multi-structure, time-consistent, dynamic risk measures induced from
conditional $g$-expectations, where the latter are associated with the
generator functionals of two backward-SDEs that implicitly take into account
the above two objectives along with the given continuous obstacle process.
Moreover, under certain conditions, we establish the existence of optimal
hierarchical risk-averse solutions, in the sense of viscosity solutions, to the
associated risk-averse dynamic programming equations that formalize the way in
which both the {\it leader} and {\it follower} consistently choose their
respective risk-averse decisions. Finally, we remark on the implication of our
result in assessing the influence of the {\it leader'}s decisions on the
risk-averseness of the {\it follower} in relation to the direction of {\it
leader-follower} information flow.


title: Challenges in Planet Formation

abstract:
  Over the past two decades, large strides have been made in the field of
planet formation. Yet fundamental questions remain. Here we review our state of
understanding of five fundamental bottlenecks in planet formation. These are:
1) the structure and evolution of protoplanetary disks; 2) the growth of the
first planetesimals; 3) orbital migration driven by interactions between
proto-planets and gaseous disk; 4) the origin of the Solar System's orbital
architecture; and 5) the relationship between observed super-Earths and our own
terrestrial planets. Given our lack of understanding of these issues, even the
most successful formation models remain on shaky ground.


title:
Octant of $\theta_{23}$ at long baseline neutrino experiments in the
  light of Non Unitary Leptonic mixing

abstract:
  The octant of the atmospheric mixing angle $\theta_{23}$ is still
undetermined by neutrino oscillation experiments. Long-baseline experiments
like NO$\nu$A, T2K and DUNE offer good prospects for determining the octant of
$\theta_{23}$. However, their capability to do so may be compromised by the
possible presence of non-unitarity in the leptonic mixing matrix. In this
paper, we study in detail the octant degeneracy with and without non-unitarity
at the level of oscillation probabilities and events for these experiments. We
also analyze their octant sensitivity and discovery reach and show that they
are hampered in the presence of non-unitarity.


title: Output-sensitive Complexity of Multiobjective Combinatorial Optimization

abstract:
  We study output-sensitive algorithms and complexity for multiobjective
combinatorial optimization problems. In this computational complexity
framework, an algorithm for a general enumeration problem is regarded efficient
if it is output-sensitive, i.e., its running time is bounded by a polynomial in
the input and the output size. We provide both practical examples of MOCO
problems for which such an efficient algorithm exists as well as problems for
which no efficient algorithm exists under mild complexity theoretic
assumptions.


title:
From worldline to quantum superconformal mechanics with/without
  oscillatorial terms: $D(2,1;\alpha)$ and $sl(2|1)$ models

abstract:
  In this paper we quantize superconformal $\sigma$-models defined by worldline
supermultiplets. Two types of superconformal mechanics, with and without a DFF
term, are considered. Without a DFF term (Calogero potential only) the
supersymmetry is unbroken. The models with a DFF term correspond to deformed
(if the Calogero potential is present) or undeformed oscillators. For these
(un)deformed oscillators the classical invariant superconformal algebra acts as
a spectrum-generating algebra of the quantum theory. Besides the $osp(1|2)$
examples, we explicitly quantize the superconformally-invariant worldine
$\sigma$-models defined by the ${\cal N}=4$ $(1,4,3)$ supermultiplet (with
$D(2,1;\alpha)$ invariance, for $\alpha\neq 0,-1$) and by the ${\cal N}=2$
$(2,2,0)$ supermultiplet (with two-dimensional target and $sl(2|1)$
invariance). The parameter $\alpha$ is the scaling dimension of the $(1,4,3)$
supermultiplet and, in the DFF case, has a direct interpretation as a vacuum
energy. In the DFF case, for the $sl(2|1)$ models, the scaling dimension
$\lambda$ is quantized (either $\lambda=\frac{1}{2}+{\mathbb Z}$ or
$\lambda={\mathbb Z}$). The ordinary two-dimensional oscillator is recovered,
after imposing a superselection restriction, from the $\lambda=-\frac{1}{2}$
model. In particular a single bosonic vacuum is selected. The spectrum of the
unrestricted two-dimensional theory is decomposed into an infinite set of
lowest weight representations of $sl(2|1)$. Extra fermionic raising operators,
not belonging to the original $sl(2|1)$ superalgebra, allow (for
$\lambda=\frac{1}{2}+{\mathbb Z}$) to construct the whole spectrum from the two
degenerate (one bosonic and one fermionic) vacua.


title: Translating solutions to the Gauss curvature flow with flat sides

abstract:
  We derive local $C^{2}$ estimates for complete non-compact translating
solitons of the Gauss curvature flow in $\mathbb{R}^3$ which are graphs over a
convex domain $\Omega$. This is closely is related to deriving local $C^{1,1}$
estimates for the degenerate Monge-Amp\'ere equation. As a result, given a
weakly convex bounded domain $\Omega$, we establish the existence of a
$C^{1,1}_{\text{loc}}$ translating soliton. In particular, when the boundary
$\partial \Omega$ has a line segment, we show the existence of flat sides of
the translator from a local a'priori non-degeneracy estimate near the
free-boundary.


title: K-theoretic obstructions to bounded t-structures

abstract:
  Schlichting conjectured that the negative K-groups of small abelian
categories vanish and proved this for noetherian abelian categories and for all
abelian categories in degree $-1$. The main results of this paper are that
$K_{-1}(E)$ vanishes when $E$ is a small stable $\infty$-category with a
bounded t-structure and that $K_{-n}(E)$ vanishes for all $n\geq 1$ when
additionally the heart of $E$ is noetherian. It follows that Barwick's theorem
of the heart holds for nonconnective K-theory spectra when the heart is
noetherian. We give several applications, to non-existence results for bounded
t-structures and stability conditions, to possible K-theoretic obstructions to
the existence of the motivic t-structure, and to vanishing results for the
negative K-groups of a large class of dg algebras and ring spectra.


title: On the maximum number of colorings of a graph

abstract:
  Let $\mathcal{C}_k(n)$ be the family of all connected $k$-chromatic graphs of
order $n$. Given a natural number $x\geq k$, we consider the problem of finding
the maximum number of $x$-colorings among graphs in $\mathcal{C}_k(n)$. When
$k\leq 3$ the answer to this problem is known, and when $k\geq 4$ the problem
is wide open. For $k\geq 4$ it was conjectured that the maximum number of
$x$-colorings is $x(x-1)\cdots (x-k+1)\,x^{n-k}$. In this article, we prove
this conjecture under the additional condition that the independence number of
the graphs is at most $2$.


title: Trap split with Laguerre-Gaussian beams

abstract:
  The optical trapping techniques have been extensively used in physics,
biophysics, micro-chemistry, and micro-mechanics to allow trapping and
manipulation of materials ranging from particles, cells, biological substances,
and polymers to DNA and RNA molecules. In this Letter, we present a convenient
and effective way to generate a novel phenomenon of trapping, named trap split,
in a conventional four-level double-\Lambda atomic system driven by four
femtosecond Laguerre-Gaussian laser pulses. We find that trap split can be
always achieved when atoms are trapped by such laser pulses, as compared to
Gaussian ones. This work would greatly facilitate the trapping and manipulating
the particles and generation of trap split. It may also suggest the possibility
of extension into new research fields, such as micro-machining and biophysics.


title: On the change of density of states in two-body interactions

abstract:
  We derive a general relation in two-body scattering theory that more directly
relates the change of density of states (DDOS) due to interaction to the shape
of the potential. The relation allows us to infer certain global properties of
the DDOS from the global properties of the potential. In particular, we show
that DDOS is negative at all energies and for all partial waves, for potentials
that are more repulsive than $+1/r^2$ everywhere. This behavior represents a
different class of global properties of DDOS from that described by the
Levinson's theorem.


title:
Covariant and infrared-free graviton two-point function in de Sitter
  spacetime II

abstract:
  The solution to the linearized Einstein equation in de Sitter (dS) spacetime
and the corresponding two-point function are explicitly written down in a gauge
with two parameters `$a$' and `$b$'. The quantization procedure, independent of
the choice of the coordinate system, is based on a rigorous group theoretical
approach. Our result takes the form of a universal spin-two
(transverse-traceless) sector and a gauge-dependent spin-zero (pure-trace)
sector. Scalar equations are derived for the structure functions of each part.
We show that the spin-two sector can be written as the resulting action of a
second-order differential operator (the spin-two projector) on a massless
minimally coupled scalar field (the spin-two structure function). The operator
plays the role of a symmetric rank-$2$ polarization tensor and has a spacetime
dependence. The calculated spin-two projector grows logarithmically with
distance and also no dS-invariant solution for either structure functions
exist. We show that the logarithmically growing part and the dS-breaking
contribution to the spin-zero part can be dropped out, respectively, for
suitable choices of parameters `$a$' and `$b$'. Considering the
transverse-traceless graviton two-point function, however, shows that dS
breaking is universal (cannot be gauged away). More exactly, if one wants to
respect the covariance and positiveness conditions, the quantization of the dS
graviton field (as for any gauge field) cannot be carried out directly in a
Hilbert space and involves unphysical negative norm states. However, a suitable
adaptation (Krein spaces) of the Gupta-Bleuler scheme for massless fields,
based on the group theoretical approach, enables us to obtain the corresponding
two-point function satisfying the conditions of locality, covariance,
transversality, index symmetrizer, and tracelessness.


title: Positive steady state in multi-species models of real food webs

abstract:
  Real food web data available in the literature presents us with the relations
between various species, sizes of these species, metabolic types of the species
and other useful information, which allows us to define parameters for the
mathematical dynamical models of these food webs, and perform theoretical
studies of these models. Unfortunately, the researches often face the problem
of the extinction of the species in such situations, which could be an
important limiting factor. In this paper, we propose a simple algorithm of
parameterisation that leads to the existence of positive steady state and
improves persistence of the species in multi-species models of real food webs.


title:
Stochastic Modeling and Statistical Inference of Intrinsic Noise in Gene
  Regulation System via Chemical Master Equation

abstract:
  Intrinsic noise, the stochastic cell-to-cell fluctuations in mRNAs and
proteins, has been observed and proved to play important roles in cellular
systems. Due to the recent development in single-cell-level measurement
technology, the studies on intrinsic noise are becoming increasingly popular
among scholars. The chemical master equation (CME) has been used to model the
evolutions of complex chemical and biological systems since 1940, and are often
served as the standard tool for modeling intrinsic noise in gene regulation
system. A CME-based model can capture the discrete, stochastic, and dynamical
nature of gene regulation system, and may offer casual and physical explanation
of the observed data at single-cell level. Nonetheless, the complexity of CME
also pose serious challenge for researchers in proposing practical modeling and
inference frameworks. In this article, we will review the existing works on the
modelings and inference of intrinsic noise in gene regulation system within the
framework of CME model. We will explore the principles in constructing a CME
model for studying gene regulation system and discuss the popular
approximations of CME. Then we will study the simulation simulation methods as
well as the analytical and numerical approaches that can be used to obtain
solution to a CME model. Finally we will summary the exiting statistical
methods that can be used to infer the unknown parameters or structures in CME
model using single-cell-level gene expression data.


title: 3D Hand Pose Tracking and Estimation Using Stereo Matching

abstract:
  3D hand pose tracking/estimation will be very important in the next
generation of human-computer interaction. Most of the currently available
algorithms rely on low-cost active depth sensors. However, these sensors can be
easily interfered by other active sources and require relatively high power
consumption. As a result, they are currently not suitable for outdoor
environments and mobile devices. This paper aims at tracking/estimating hand
poses using passive stereo which avoids these limitations. A benchmark with
18,000 stereo image pairs and 18,000 depth images captured from different
scenarios and the ground-truth 3D positions of palm and finger joints (obtained
from the manual label) is thus proposed. This paper demonstrates that the
performance of the state-of-the art tracking/estimation algorithms can be
maintained with most stereo matching algorithms on the proposed benchmark, as
long as the hand segmentation is correct. As a result, a novel stereo-based
hand segmentation algorithm specially designed for hand tracking/estimation is
proposed. The quantitative evaluation demonstrates that the proposed algorithm
is suitable for the state-of-the-art hand pose tracking/estimation algorithms
and the tracking quality is comparable to the use of active depth sensors under
different challenging scenarios.


title: Enhancement of small-scale turbulent dynamo by large-scale shear

abstract:
  Small-scale dynamos are ubiquitous in a broad range of turbulent flows with
large-scale shear, ranging from solar and galactic magnetism to accretion
disks, cosmology and structure formation. Using high-resolution direct
numerical simulations we show that in non-helically forced turbulence with zero
mean magnetic field, large-scale shear supports small-scale dynamo action,
i.e., the dynamo growth rate increases with shear and shear enhances or even
produces turbulence, which, in turn, further increases the dynamo growth rate.
When the production rates of turbulent kinetic energy due to shear and forcing
are comparable, we find scalings for the growth rate $\gamma$ of the
small-scale dynamo and the turbulent velocity $u_{\rm rms}$ with shear rate $S$
that are independent of the magnetic Prandtl number: $\gamma \propto |S|$ and
$u_{\rm rms} \propto |S|^{2/3}$. For large fluid and magnetic Reynolds numbers,
$\gamma$, normalized by its shear-free value, depends only on shear. Having
compensated for shear-induced effects on turbulent velocity, we find that the
normalized growth rate of the small-scale dynamo exhibits the scaling,
$\widetilde{\gamma}\propto |S|^{2/3}$, arising solely from the induction
equation for a given velocity field.


title:
Inertial Regularization and Selection (IRS): Sequential Regression in
  High-Dimension and Sparsity

abstract:
  In this paper, we develop a new sequential regression modeling approach for
data streams. Data streams are commonly found around us, e.g in a retail
enterprise sales data is continuously collected every day. A demand forecasting
model is an important outcome from the data that needs to be continuously
updated with the new incoming data. The main challenge in such modeling arises
when there is a) high dimensional and sparsity, b) need for an adaptive use of
prior knowledge, and/or c) structural changes in the system. The proposed
approach addresses these challenges by incorporating an adaptive L1-penalty and
inertia terms in the loss function, and thus called Inertial Regularization and
Selection (IRS). The former term performs model selection to handle the first
challenge while the latter is shown to address the last two challenges. A
recursive estimation algorithm is developed, and shown to outperform the
commonly used state-space models, such as Kalman Filters, in experimental
studies and real data.


title: Sets of Priors Reflecting Prior-Data Conflict and Agreement

abstract:
  In Bayesian statistics, the choice of prior distribution is often debatable,
especially if prior knowledge is limited or data are scarce. In imprecise
probability, sets of priors are used to accurately model and reflect prior
knowledge. This has the advantage that prior-data conflict sensitivity can be
modelled: Ranges of posterior inferences should be larger when prior and data
are in conflict. We propose a new method for generating prior sets which, in
addition to prior-data conflict sensitivity, allows to reflect strong
prior-data agreement by decreased posterior imprecision.


title: Eulerian polynomials and descent statistics

abstract:
  We prove several identities expressing polynomials counting permutations by
various descent statistics in terms of Eulerian polynomials, extending results
of Stembridge, Petersen, and Br\"and\'en. Additionally, we find $q$-exponential
generating functions for $q$-analogues of these descent statistic polynomials
that also keep track of the inversion number or inverse major index. We also
present identities relating several of these descent statistic polynomials to
refinements of type B Eulerian polynomials and flag descent polynomials by the
number of negative letters of a signed permutation. Our methods include
permutation enumeration techniques involving noncommutative symmetric
functions, Br\"and\'en's modified Foata-Strehl action, and a group action of
Petersen on signed permutations. Notably, the modified Foata-Strehl action
yields an analogous relation between Narayana polynomials and the joint
distribution of the peak number and descent number over 231-avoiding
permutations, which we also interpret in terms of binary trees and Dyck paths.


title: Maximizing the number of $x$-colorings of $4$-chromatic graphs

abstract:
  Let $\mathcal{C}_4(n)$ be the family of all connected $4$-chromatic graphs of
order $n$. Given an integer $x\geq 4$, we consider the problem of finding the
maximum number of $x$-colorings of a graph in $\mathcal{C}_4(n)$. It was
conjectured that the maximum number of $x$-colorings is equal to
$(x)_{\downarrow 4}(x-1)^{n-4}$ and the extremal graphs are those which have
clique number $4$ and size $n+2$.
  In this article, we reduce this problem to a \textit{finite} family of
graphs. We show that there exist a finite family $\mathcal{F}$ of connected
$4$-chromatic graphs such that if the number of $x$-colorings of every graph
$G$ in $\mathcal{F}$ is less than $(x)_{\downarrow 4}(x-1)^{|V(G)|-4}$ then the
conjecture holds to be true.


title: Partitioning Trillion-edge Graphs in Minutes

abstract:
  We introduce XtraPuLP, a new distributed-memory graph partitioner designed to
process trillion-edge graphs. XtraPuLP is based on the scalable label
propagation community detection technique, which has been demonstrated as a
viable means to produce high quality partitions with minimal computation time.
On a collection of large sparse graphs, we show that XtraPuLP partitioning
quality is comparable to state-of-the-art partitioning methods. We also
demonstrate that XtraPuLP can produce partitions of real-world graphs with
billion+ vertices in minutes. Further, we show that using XtraPuLP partitions
for distributed-memory graph analytics leads to significant end-to-end
execution time reduction.


title:
Resilience by Structural Entrenchment: Dynamics of Single-Layer and
  Multiplex Networks Following Sudden Changes to Tie Costs

abstract:
  We examine a model of network formation in single-layer and multiplex
networks in which individuals have positive incentives for social ties, closed
triangles, and spillover edges. In particular, we investigate the influence of
shocks to the network in which the cost of social ties changes after an initial
equilibrium. We highlight the emergence of structural entrenchment: the
retention of structural features, such as closed triangles and spillover edges,
which are formed under historically different conditions from those currently
driving network evolution. This work has broad implications for understanding
path dependence in the structure and dynamics of single-layer and multiplex
networks.


title:
Robust Bayesian Reliability for Complex Systems under Prior-Data
  Conflict

abstract:
  In reliability engineering, data about failure events is often scarce. To
arrive at meaningful estimates for the reliability of a system, it is therefore
often necessary to also include expert information in the analysis, which is
straightforward in the Bayesian approach by using an informative prior
distribution. A problem called prior-data conflict then can arise: observed
data seem very surprising from the viewpoint of the prior, i.e., information
from data is in conflict with prior assumptions. Models based on conjugate
priors can be insensitive to prior-data conflict, in the sense that the spread
of the posterior distribution does not increase in case of such a conflict,
thus conveying a false sense of certainty. An approach to mitigate this issue
is presented, by considering sets of prior distributions to model limited
knowledge on Weibull distributed component lifetimes, treating systems with
arbitrary layout using the survival signature. This approach can be seen as a
robust Bayesian procedure or imprecise probability method that reflects
surprisingly early or late component failures by wider system reliability
bounds.


title: Automorphisms acting on the left-orderings of a bi-orderable group

abstract:
  We generalize a result of T. Koberda by showing that the natural action of
the automorphism group on the space of left-orderings is faithful for all
nonabelian bi-orderable groups G, as well as for a certain class of
left-orderable groups that includes the braid groups. As a corollary we show
that the action of the automorphism group of G on the boundary of G is faithful
whenever G is bi-orderable and hyperbolic. We also analyze the action of the
commensurator of G on its space of virtual left-orderings.


title:
On the Hyperbolicity and Stability of $3+1$ Formulations of Metric
  $f(R)$ Gravity

abstract:
  $3+1$ formulations of the Einstein field equations have become an invaluable
tool in Numerical relativity, having been used successfully in modeling
spacetimes of black hole collisions, stellar collapse and other complex
systems. It is plausible that similar considerations could prove fruitful for
modified gravity theories. In this article, we pursue from a numerical
relativistic viewpoint the $3+1$ formulation of metric $f(R)$ gravity as it
arises from the fourth order equations of motion, without invoking the
dynamical equivalence with Brans-Dicke theories. We present the resulting
system of evolution and constraint equations for a generic function $f(R)$,
subject to the usual viability conditions. We confirm that the time propagation
of the $f(R)$ Hamiltonian and Momentum constraints take the same Mathematical
form as in general relativity, irrespective of the $f(R)$ model. We further
recast the 3+1 system in a form akin to the BSSNOK formulation of numerical
relativity. Without assuming any specific model, we show that the ADM version
of $f(R)$ is weakly hyperbolic and is plagued by similar zero speed modes as in
the general relativity case. On the other hand the BSSNOK version is strongly
hyperbolic and hence a promising formulation for numerical simulations in
metric $f(R)$ theories.


title: A deformation of the Curtright action

abstract:
  We present a deformation of the action principle for a free tensor field of
mixed symmetry (2,1) --the Curtright action, a dual formulation of
five-dimensional linearized gravity. It is constructed as the dual theory of
the Einstein-Hilbert action linearized around a de Sitter background, and its
derivation relies on the use of the two-potential formalism as an intermediate
step. The resulting action principle is spatially non-local and space-time
covariance is not manifest, thus overcoming previous no-go results.


title:
Thermodynamic Anomaly Above the Superconducting Critical Temperature in
  the Quasi One-Dimensional Superconductor Ta$_4$Pd$_3$Te$_{16}$

abstract:
  We study the intrinsic transport anisotropy and fermiology of the quasi
one-dimensional superconductor Ta$_4$Pd$_3$Te$_{16}$. Below $T^*=20$ K we
detect a thermodynamic phase transition that predominantly affects the
conductivity perpendicular to the quasi one-dimensional chains, consistent with
a thermodynamic transition related to the presence of charge order that
precedes superconductivity. Remarkably the Fermi surface pockets detected by de
Haas-van Alphen (dHvA) oscillations are unaffected by this transition,
suggesting that the ordered state does not break any translational symmetries
but rather alters the scattering of the quasiparticles themselves.


title: Sums of squares in Quaternion rings

abstract:
  Lagrange's Four Squares Theorem states that any positive integer can be
expressed as the sum of four integer squares. We investigate the analogous
question over Quaternion rings, focusing on squares of elements of Quaternion
rings with integer coefficients. We determine the minimum necessary number of
squares for infinitely many Quaternion rings, and give global upper and lower
bounds.


title:
Precise measurements on a quantum phase transition in antiferromagnetic
  spinor Bose-Einstein condensates

abstract:
  We have experimentally investigated the quench dynamics of antiferromagnetic
spinor Bose-Einstein condensates in the vicinity of a zero temperature quantum
phase transition at zero quadratic Zeeman shift $q$. The rate of instability
shows good agreement with predictions based upon solutions to the Bogoliubov
de-Gennes equations. A key feature of this work was removal of magnetic field
inhomogeneities, resulting in a steep change in behavior near the transition
point. The quadratic Zeeman shift at the transition point was resolved to 250
milliHertz uncertainty, equivalent to an energy resolution of $k_B \times 12$
picoKelvin. To our knowledge, this is the first demonstration of sub-Hz
precision measurement of a phase transition in quantum gases. Our results point
to the use of dynamics, rather than equilibrium studies for high precision
measurements of phase transitions in quantum gases.


title: A Polynomial Kernel for Distance-Hereditary Vertex Deletion

abstract:
  A graph is distance-hereditary if for any pair of vertices, their distance in
every connected induced subgraph containing both vertices is the same as their
distance in the original graph. The Distance-Hereditary Vertex Deletion problem
asks, given a graph $G$ on $n$ vertices and an integer $k$, whether there is a
set $S$ of at most $k$ vertices in $G$ such that $G-S$ is distance-hereditary.
This problem is important due to its connection to the graph parameter
rank-width that distance-hereditary graphs are exactly graphs of rank-width at
most $1$. Eiben, Ganian, and Kwon (MFCS' 16) proved that Distance-Hereditary
Vertex Deletion can be solved in time $2^{\mathcal{O}(k)}n^{\mathcal{O}(1)}$,
and asked whether it admits a polynomial kernelization. We show that this
problem admits a polynomial kernel, answering this question positively. For
this, we use a similar idea for obtaining an approximate solution for Chordal
Vertex Deletion due to Jansen and Pilipczuk (SODA' 17) to obtain an approximate
solution with $\mathcal{O}(k^3\log n)$ vertices when the problem is a
YES-instance, and we exploit the structure of split decompositions of
distance-hereditary graphs to reduce the total size.


title: Merging white dwarfs and SN Ia

abstract:
  Using population synthesis, we study a double-degenerate (DD) scenario for
SNe Ia, aiming to estimate the maximum possible contribution to the rate of SNe
from this scenario and the dependence of the delay-time distribution (DTD) on
it. We make an extreme assumption that all mergers of super-Chandrasekhar pairs
of CO white dwarfs (WDs) and mergers of CO WDs more massive than 0.47 $M_\odot$
with hybrid or helium WDs more massive than 0.37$M_\odot$ produce SNe Ia. The
models are parametrized by the product of the common envelope efficiency and
the parameter of binding energy of stellar envelopes $\alpha_{ce}\lambda$,
which we vary between 0.25 and 2. The best agreement with observations is
obtained for $\alpha_{ce}\lambda$=2. A substantial contribution to the rate of
SNe Ia is provided by the pairs with a hybrid WD. The estimated Galactic rate
of SNe Ia is $6.5 10^{-3}$ per yr (for the mass of the bulge and thin disk
equal to $7.2 10^{10} M_\odot$), which is comparable to the observational
estimate $(5.4\pm0.12) 10^{-3}$ per yr. The model DTD for 1 to 8 Gyr range
satisfactorily fits DTD for SNe Ia in the field galaxies (Maoz et al. 2012).
For this epoch, model DTD is a power low with an index -1.64. At earlier and
later epochs our DTD has a deficit of events, as in other studies. Marginal
agreement with observational DTD is achieved even if only CO+CO WD with
$M_1\geq0.8\,M_\odot$ and $M_2\geq0.6\,M_\odot$ produce SNe Ia. A better
agreement of observed and model DTD may be obtained if tidal effects are weaker
than assumed and/or metallicity of population is much lower than solar.


title: Template Matching Advances and Applications in Image Analysis

abstract:
  In most computer vision and image analysis problems, it is necessary to
define a similarity measure between two or more different objects or images.
Template matching is a classic and fundamental method used to score
similarities between objects using certain mathematical algorithms. In this
paper, we reviewed the basic concept of matching, as well as advances in
template matching and applications such as invariant features or novel
applications in medical image analysis. Additionally, deformable models and
templates originating from classic template matching were discussed. These
models have broad applications in image registration, and they are a
fundamental aspect of novel machine vision or deep learning algorithms, such as
convolutional neural networks (CNN), which perform shift and scale invariant
functions followed by classification. In general, although template matching
methods have restrictions which limit their application, they are recommended
for use with other object recognition methods as pre- or post-processing steps.
Combining a template matching technique such as normalized cross-correlation or
dice coefficient with a robust decision-making algorithm yields a significant
improvement in the accuracy rate for object detection and recognition.


title: Symbolic Iterative Solution of Two-Point Boundary Value Problems

abstract:
  In this work we give an efficient method involving symbolic manipulation,
Picard iteration, and auxiliary variables for approximating solutions of
two-point boundary value problems.


title: Efficient Global Indoor Localization for Micro Aerial Vehicles

abstract:
  Indoor localization for autonomous micro aerial vehicles (MAVs) requires
specific localization techniques, since the Global Positioning System (GPS) is
usually not available. We present an efficient onboard computer vision approach
that estimates 2D positions of an MAV in real-time. This global localization
system does not suffer from error accumulation over time and uses a $k$-Nearest
Neighbors ($k$-NN) algorithm to predict positions based on textons---small
characteristic image patches that capture the texture of an environment. A
particle filter aggregates the estimates and resolves positional ambiguities.
To predict the performance of the approach in a given setting, we developed an
evaluation technique that compares environments and identifies critical areas
within them. We conducted flight tests to demonstrate the applicability of our
approach. The algorithm has a localization accuracy of approximately 0.6 m on a
5 m$\times$5 m area at a runtime of 32 ms on board of an MAV. Based on random
sampling, its computational effort is scalable to different platforms, trading
off speed and accuracy.


title:
Indirect Interactions Between Proton Donors Separated by Several
  Hydrogen Bonds

abstract:
  We expand the definition of our recently proposed proton conduction
mechanism, the packed-acid mechanism, which occurs under conditions of
concentrated proton donors. The original definition stated that acid-acid
interactions, which help overcome the barrier of the rate-determining step,
occur only when a hydrogen bond is formed directly between proton donors. Here,
it is shown that proton donors can interact with each other even when the
donors are separated via several H-bonds. The effect of these interactions on
proton diffusivity is confirmed by ab initio calculations.


title: Spectral Analysis Code: PARAS SPEC

abstract:
  The light emitted from the stellar photosphere serves as a unique signature
for the nature of stars. The behaviour of these stellar lines depend upon the
surface temperature, mass, evolutionary status and chemical composition of the
star. With the advent of high-resolution spectrographs coupled with medium to
large aperture telescopes around the globe, there is plenty of high-resolution
and high signal-to-noise ratio data available to the astronomy community. Apart
from radial velocity (RV) studies, such data offer us the unique opportunity to
study chemical composition and atmospheric properties of the star. The
procedure used to derive these parameters must be automated and well adaptable
to data available from any high-resolution spectrograph. We hereby present an
IDL code, PARAS SPEC, which was primary designed to handle high-resolution
spectroscopy data from PARAS spectrograph coupled with the 1.2~m telescope at
Mt. Abu, India. This code is designed to adapt with data from other
spectrographs as well. The code PARAS SPEC estimates the stellar atmospheric
parameters from the analysis of stellar spectra based on two primary methods,
synthetic spectral fitting and equivalent width method. Synthetic spectral
fitting method involves fitting of the observed spectrum with different
synthetic spectra for a set of stellar parameters. The second method is based
on equivalent widths (EWs) that are used to derive abundances for a set of Fe~I
and Fe~II lines from the observed spectra. The detailed methodology used to
design this code and comparison of the results from literature values are
presented in this paper.


title: Hybrid Static/Dynamic Schedules for Tiled Polyhedral Programs

abstract:
  Polyhedral compilers perform optimizations such as tiling and
parallelization; when doing both, they usually generate code that executes
"barrier-synchronized wavefronts" of tiles. We present a system to express and
generate code for hybrid schedules, where some constraints are automatically
satisfied through the structure of the code, and the remainder are dynamically
enforced at run-time with data flow mechanisms. We prove bounds on the added
overheads that are better, by at least one polynomial degree, than those of
previous techniques.
  We propose a generic mechanism to implement the needed synchronization, and
show it can be easily realized for a variety of targets: OpenMP, Pthreads, GPU
(CUDA or OpenCL) code, languages like X10, Habanero, Cilk, as well as data flow
platforms like DAGuE, and OpenStream and MPI. We also provide a simple concrete
implementation that works without the need of any sophisticated run-time
mechanism.
  Our experiments show our simple implementation to be competitive or better
than the wavefront-synchronized code generated by other systems. We also show
how the proposed mechanism can achieve 24% to 70% reduction in energy.


title:
Tripartite Bell-type inequalities for measures of quantum coherence and
  skew information

abstract:
  We construct the tripartite Bell-type inequalities of product states for
l1-norm of coherence, relative entropy of coherence and skew information. Some
three-qubit entangled states violate these inequalities. Particulary, the
tripartite Bell-type inequality for relative entropy of coherence is always
violated by the W class pure or mixed states as well as the GHZ class pure or
mixed states, being used as entanglement witness.


title: SPiKeS: Superpixel-Keypoints Structure for Robust Visual Tracking

abstract:
  In visual tracking, part-based trackers are attractive since they are robust
against occlusion and deformation. However, a part represented by a rectangular
patch does not account for the shape of the target, while a superpixel does
thanks to its boundary evidence. Nevertheless, tracking superpixels is
difficult due to their lack of discriminative power. Therefore, to enable
superpixels to be tracked discriminatively as object parts, we propose to
enhance them with keypoints. By combining properties of these two features, we
build a novel element designated as a Superpixel-Keypoints structure (SPiKeS).
Being discriminative, these new object parts can be located efficiently by a
simple nearest neighbor matching process. Then, in a tracking process, each
match votes for the target's center to give its location. In addition, the
interesting properties of our new feature allows the development of an
efficient model update for more robust tracking. According to experimental
results, our SPiKeS-based tracker proves to be robust in many challenging
scenarios by performing favorably against the state-of-the-art.


title:
Determining Transport Coefficients for a Microscopic Simulation of a
  Hadron Gas

abstract:
  Quark-Gluon plasmas produced in relativistic heavy-ion collisions quickly
expand and cool, entering a phase consisting of multiple interacting hadronic
resonances just below the QCD deconfinement temperature, $T\sim 155$ MeV.
Numerical microscopic simulations have emerged as the principal method for
modeling the behavior of the hadronic stage of heavy-ion collisions, but the
transport properties that characterize these simulations are not well
understood. Methods are presented here for extracting the shear viscosity, and
two transport parameters that emerge in Israel-Stewart hydrodynamics. The
analysis is based on studying how the stress-energy tensor responds to velocity
gradients. Results agree with expectations based on Kubo relations.


title:
Are mmWave Low-Complexity Beamforming Structures Energy-Efficient?
  Analysis of the Downlink MU-MIMO

abstract:
  Future cellular systems based on the use of above-6 GHz frequencies, the
so-called millimeter wave (mmWave) bandwidths, will heavily rely on the use of
antenna arrays both at the transmitter and at the receiver, possibly with a
large number of elements. For complexity reasons, fully digital precoding and
postcoding structures may turn out to be unfeasible, and thus suboptimal
structures, making use of simplified hardware and a limited number of RF
chains, have been investigated. This paper considers and makes a comparative
assessment, both from a spectral efficiency and energy efficiency point of
view, of several suboptimal precoding and postcoding beamforming structures for
the downlink of a cellular multiuser MIMO (MU-MIMO) system. Based on the most
recently available data for the energy consumption of phase shifters and
switches, we show that there are cases where fully-digital beamformers may
achieve a larger energy efficiency than lower-complexity solutions, as well as
that structures based on the exclusive use of switches achieve quite
unsatisfactory performance in realistic scenarios.


title: From Ontology to Structured Applied Epistemology

abstract:
  Developing and organizing new knowledge is a core activity for scholars.
Recently, ontologies have been introduced as an approach for organizing
knowledge. However, most ontologies do not readily support the development and
organization of new knowledge. By comparison, to ontology, epistemology is the
study of what can be known. Aspects of epistemology include the acquisition of
and justification for new knowledge. Thus, we need to coordinate ontology with
epistemology. Because we are developing frameworks for capturing knowledge
across several scholarly domains, we describe the work in this paper as
exploring structured applied epistemology. Unlike other recent proposals for
new approaches to scholarly publishing, we propose an integrated and
comprehensive approach. We have explored direct representation based on the
rigorous Basic Formal Ontology and in this paper, we consider how epistemology
can be incorporated with that. In addition to highly-structured scientific
research reports, we also consider how to develop highly-structured
descriptions of historical events on which historical analyses can be based.


title: Semistable Graph Homology

abstract:
  Using the orbicell decomposition of the Deligne-Mumford compactification of
the moduli space of Riemann surfaces studied previously, a chain complex based
on semistable ribbon graphs is constructed which is an extension of Konsevich's
graph homology.


title:
Quantum Chromodynamics, Antiferromagnets and XY Models from a Unified
  Point of View

abstract:
  Antiferromagnets and quantum XY magnets in three space dimensions are
described by an effective Lagrangian that exhibits the same structure as the
effective Lagrangian of quantum chromodynamics with two light flavors. These
systems all share a spontaneously broken internal symmetry O($N$) $\to$
O($N$-1). Although the respective scales differ by many orders of magnitude,
the general structure of the low-temperature expansion of the partition
function is the same. In the nonabelian case, logarithmic terms of the form
$T^8 \ln T$ emerge at three-loop order, while for $N$=2 the series only
involves powers of $T^2$. The manifestation of the Goldstone boson interaction
in the pressure, order parameter, and susceptibility is explored in presence of
an external field.


title: Power of one non-clean qubit

abstract:
  The one-clean qubit model (or the DQC1 model) is a restricted model of
quantum computing where only a single qubit of the initial state is pure and
others are maximally mixed. Although the model is not universal, it can
efficiently solve several problems whose classical efficient solutions are not
known. Furthermore, it was recently shown that if the one-clean qubit model is
classically efficiently simulated, the polynomial hierarchy collapses to the
second level. A disadvantage of the one-clean qubit model is, however, that the
clean qubit is too clean: for example, in realistic NMR experiments,
polarizations are not enough high to have the perfectly pure qubit. In this
paper, we consider a more realistic one-clean qubit model, where the clean
qubit is not clean, but depolarized. We first show that, for any polarization,
a multiplicative-error calculation of the output probability distribution of
the model is possible in a classical polynomial time if we take an
appropriately large multiplicative error. The result is in a strong contrast to
that of the ideal one-clean qubit model where the classical efficient
multiplicative-error calculation (or even the sampling) with the same amount of
error causes the collapse of the polynomial hierarchy. We next show that, for
any polarization lower-bounded by an inverse polynomial, a classical efficient
sampling (in terms of a sufficiently small multiplicative error or an
exponentially-small additive error) of the output probability distribution of
the model is impossible unless BQP is contained in the second level of the
polynomial hierarchy, which suggests the hardness of the classical efficient
simulation of the one non-clean qubit model.

categories: quant-ph cond-mat.stat-mech cond-mat.str-el cs.CC


title:
Toward Personalized Training and Skill Assessment in Robotic Minimally
  Invasive Surgery

abstract:
  Despite the immense technology advancement in the surgeries the criteria of
assessing the surgical skills still remains based on subjective standards. With
the advent of robotic-assisted surgery, new opportunities for objective and
autonomous skill assessment is introduced. Previous works in this area are
mostly based on structured-based method such as Hidden Markov Model (HMM) which
need enormous pre-processing. In this study, in contrast with them, we develop
a new shaped-based framework for automatically skill assessment and
personalized surgical training with minimum parameter tuning. Our work has
addressed main aspects of skill evaluation; develop gesture recognition model
directly on temporal kinematic signal of robotic-assisted surgery, and build
automated personalized RMIS gesture training framework which . We showed that
our method, with an average accuracy of 82% for suturing, 70% for needle
passing and 85% for knot tying, performs better or equal than the
state-of-the-art methods, while simultaneously needs minimum pre-processing,
parameter tuning and provides surgeons with online feedback for their
performance during training.


title:
Relaxation of photoexcitations in polaron-induced magnetic
  microstructures

abstract:
  We investigate the evolution of a photoexcitation in correlated materials
over a wide range of time scales. The system studied is a one-dimensional model
of a manganite with correlated electron, spin, orbital, and lattice degrees of
freedom, which we relate to the three-dimensional material
Pr$_{1-x}$Ca$_{x}$MnO$_3$. The ground-state phases for the entire composition
range are determined and rationalized by a coarse-grained polaron model. At
half-doping a pattern of antiferromagnetically coupled Zener polarons is
realized. Using time-dependent density-matrix renormalization group (tDMRG), we
treat the electronic quantum dynamics following the excitation. The emergence
of quasiparticles is addressed, and the relaxation of the nonequilibrium
quasiparticle distribution is investigated via a linearized quantum-Boltzmann
equation. Our approach shows that the magnetic microstructure caused by the
Zener polarons leads to an increase of the relaxation times of the excitation.


title: Radiative transfer modelling of parsec-scale dusty warped discs

abstract:
  Warped discs have been found on (sub-)parsec scale in some nearby Seyfert
nuclei, identified by their maser emission. Using dust radiative transfer
simulations we explore their observational signatures in the infrared in order
to find out whether they can partly replace the molecular torus. Strong
variations of the brightness distributions are found, depending on the
orientation of the warp with respect to the line of sight. Whereas images at
short wavelengths typically show a disc-like and a point source component, the
warp itself only becomes visible at far-infrared wavelengths. A similar variety
is visible in the shapes of the spectral energy distributions. Especially for
close to edge-on views, the models show silicate feature strengths ranging from
deep absorption to strong emission for variations of the lines of sight towards
the warp. To test the applicability of our model, we use the case of the
Circinus galaxy, where infrared interferometry has revealed a highly elongated
emission component matching a warped maser disc in orientation and size. Our
model is for the first time able to present a physical explanation for the
observed dust morphology as coming from the AGN heated dust. As opposed to
available torus models, a warped disc morphology produces a variety of silicate
feature shapes for grazing lines of sight, close to an edge-on view. This could
be an attractive alternative to a claimed change of the dust composition for
the case of the nearby Seyfert 2 galaxy NGC 1068, which harbours a warped maser
disc as well.


title:
Irregular Stochastic differential equations driven by a family of Markov
  processes

abstract:
  Using heat kernel estimates, we prove the pathwise uniqueness for strong
solutions of irregular stochastic differential equation driven by a family of
Markov process, whose generator is a non-local and non-symmetric L\'evy type
operator. Due to the extra term $1_{[0,\sigma(X_{s-},z)]}(r)$ in multiplicative
noise, we need to derive some new regularity results for the generator and use
a trick of mixing $L_1$ and $L_2$-estimates by Kurtz and Protter \cite{Ku-Po}.


title:
Spitzer Observations Confirm and Rescue the Habitable-Zone Super-Earth
  K2-18b for Future Characterization

abstract:
  The recent detections of two transit events attributed to the super-Earth
candidate K2-18b have provided the unprecedented prospect of spectroscopically
studying a habitable-zone planet outside the Solar System. Orbiting a nearby
M2.5 dwarf and receiving virtually the same stellar insolation as Earth, K2-18b
would be a prime candidate for the first detailed atmospheric characterization
of a habitable-zone exoplanet using HST and JWST. Here, we report the detection
of a third transit of K2-18b near the predicted transit time using the Spitzer
Space Telescope. The Spitzer detection demonstrates the periodic nature of the
two transit events discovered by K2, confirming that K2-18 is indeed orbited by
a super-Earth in a 33-day orbit and ruling out the alternative scenario of two
similarly-sized, long-period planets transiting only once within the 75-day K2
observation. We also find, however, that the transit event detected by Spitzer
occurred 1.85 hours (7-sigma) before the predicted transit time. Our joint
analysis of the Spitzer and K2 photometry reveals that this early occurrence of
the transit is not caused by transit timing variations (TTVs), but the result
of an inaccurate K2 ephemeris due to a previously undetected data anomaly in
the K2 photometry likely caused by a cosmic ray hit. We refit the ephemeris and
find that K2-18b would have been lost for future atmospheric characterizations
with HST and JWST if we had not secured its ephemeris shortly after the
discovery. We caution that immediate follow-up observations as presented here
will also be critical in confirming and securing future planets discovered by
TESS, in particular if only two transit events are covered by the relatively
short 27-day TESS campaigns.


title: Random Multiple Access for M2M Communications with QoS Guarantees

abstract:
  We propose a novel random multiple access (RMA) scheme with quality of
service (QoS) guarantees for machine-to-machine (M2M) communications. We
consider a slotted uncoordinated data transmission period during which machine
type communication (MTC) devices transmit over the same radio channel. Based on
the latency requirements, MTC devices are divided into groups of different
sizes, and the transmission frame is divided into subframes of different
lengths. In each subframe, each group is assigned an access probability based
on which an MTC device decides to transmit replicas of its packet or remain
silent. The base station (BS) employs successive interference cancellation
(SIC) to recover all the superposed packets. We derive the closed form
expressions for the average probability of device resolution for each group,
and we use these expressions to design the access probabilities. The accuracy
of the expressions is validated through Monte Carlo simulations. We show that
the designed access probabilities can guarantee the QoS requirements with high
reliability and high energy efficiency. Finally, we show that RMA can
outperform standard coordinated access schemes as well as some of the recently
proposed M2M access schemes for cellular networks.


title:
Large-Scale Classification of IPv6-IPv4 Siblings with Variable Clock
  Skew

abstract:
  Linking the growing IPv6 deployment to existing IPv4 addresses is an
interesting field of research, be it for network forensics, structural
analysis, or reconnaissance. In this work, we focus on classifying pairs of
server IPv6 and IPv4 addresses as siblings, i.e., running on the same machine.
Our methodology leverages active measurements of TCP timestamps and other
network characteristics, which we measure against a diverse ground truth of 682
hosts. We define and extract a set of features, including estimation of
variable (opposed to constant) remote clock skew. On these features, we train a
manually crafted algorithm as well as a machine-learned decision tree. By
conducting several measurement runs and training in cross-validation rounds, we
aim to create models that generalize well and do not overfit our training data.
We find both models to exceed 99% precision in train and test performance. We
validate scalability by classifying 149k siblings in a large-scale measurement
of 371k sibling candidates. We argue that this methodology, thoroughly
cross-validated and likely to generalize well, can aid comparative studies of
IPv6 and IPv4 behavior in the Internet. Striving for applicability and
replicability, we release ready-to-use source code and raw data from our study.


title: Information-theoretic Physical Layer Security for Satellite Channels

abstract:
  Shannon introduced the classic model of a cryptosystem in 1949, where Eve has
access to an identical copy of the cyphertext that Alice sends to Bob. Shannon
defined perfect secrecy to be the case when the mutual information between the
plaintext and the cyphertext is zero. Perfect secrecy is motivated by
error-free transmission and requires that Bob and Alice share a secret key.
Wyner in 1975 and later I.~Csisz\'ar and J.~K\"orner in 1978 modified the
Shannon model assuming that the channels are noisy and proved that secrecy can
be achieved without sharing a secret key. This model is called wiretap channel
model and secrecy capacity is known when Eve's channel is noisier than Bob's
channel.
  In this paper we review the concept of wiretap coding from the satellite
channel viewpoint. We also review subsequently introduced stronger secrecy
levels which can be numerically quantified and are keyless unconditionally
secure under certain assumptions. We introduce the general construction of
wiretap coding and analyse its applicability for a typical satellite channel.
From our analysis we discuss the potential of keyless information theoretic
physical layer security for satellite channels based on wiretap coding. We also
identify system design implications for enabling simultaneous operation with
additional information theoretic security protocols.


title: Dual Ore's theorem for distributive intervals of small index

abstract:
  This paper proves a dual version of a theorem of Oystein Ore for every
distributive interval of finite groups [H,G] of index |G:H|<9720, and for every
boolean interval of rank <7. It has applications to representation theory for
every finite group.


title: Minimum triplet covers of binary phylogenetic $X$-trees

abstract:
  Trees with labelled leaves and with all other vertices of degree three play
an important role in systematic biology and other areas of classification. A
classical combinatorial result ensures that such trees can be uniquely
reconstructed from the distances between the leaves (when the edges are given
any strictly positive lengths). Moreover, a linear number of these pairwise
distance values suffices to determine both the tree and its edge lengths. A
natural set of pairs of leaves is provided by any `triplet cover' of the tree
(based on the fact that each non-leaf vertex is the median vertex of three
leaves). In this paper we describe a number of new results concerning triplet
covers of minimum size. In particular, we characterize such covers in terms of
an associated graph being a 2-tree. Also, we show that minimum triplet covers
are `shellable' and thereby provide a set of pairs for which the inter-leaf
distance values will uniquely determine the underlying tree and its associated
branch lengths.


title:
Negative dispersion medium at 1064 nm in an optomechanical resonator for
  enhancing the sensitivity bandwidth in a gravitational-wave detector

abstract:
  Recently, we had proposed an optically-pumped five-level Gain EIT (GEIT)
system, which has a transparency dip superimposed on a gain profile and
exhibits a negative dispersion suitable for the white light cavity (WLC)
enhanced interferometric gravitational wave detector [Phys. Rev. D. 92, 082002
(2015)]. Using this system as the negative dispersion medium (NDM) in the
WLC-SR (signal recycling) scheme, we get an enhancement in the quantum noise
(QN) limited sensitivity-bandwidth product by a factor of ~18. We have also
shown how to realize such a system in practice using Zeeman sublevels in
$^{87}$Rb at 795nm [Opt. Commun. 402, 382-388 (2017)]. However, aLIGO operates
at 1064nm and suitable transitions in Rb or other alkali atoms are not
available at this wavelength. Therefore, it is necessary to consider a system
that is consistent with the operating wavelength of aLIGO. Here, we present the
realization of such an NDM at 1064nm with a microresonator, which supports
optomechanical interaction. A strong control field is applied at a higher
frequency, and, under certain conditions, a probe field at a lower frequency
experiences a peak at the center of an absorption profile, and a negative
dispersion in the transmission. Unlike in the GEIT case, we use the
compound-cavity signal-recycling (CC-SR) scheme, where an auxiliary mirror is
inserted in the dark port of the detector, and show that the enhancement factor
can be as high as ~15. However, using the parameters required for the
sensitivity enhancement, the optomechanical system enters an instability region
where the control field is depleted. We present an observer based feedback
control process used to stabilize the CC-SR system.


title:
Differential Modulation for Asynchronous Two-Way-Relay Systems over
  Frequency-Selective Fading Channels

abstract:
  In this paper, we propose two schemes for asynchronous multi-relay two-way
relay (MR-TWR) systems in which neither the users nor the relays know the
channel state information (CSI). In an MR-TWR system, two users exchange their
messages with the help of $N_R$ relays. Most of the existing works on MR-TWR
systems based on differential modulation assume perfect symbol-level
synchronization between all communicating nodes. However, this assumption is
not valid in many practical systems, which makes the design of differentially
modulated schemes more challenging. Therefore, we design differential
modulation schemes that can tolerate timing misalignment under
frequency-selective fading. We investigate the performance of the proposed
schemes in terms of either probability of bit error or pairwise error
probability. Through numerical examples, we show that the proposed schemes
outperform existing competing solutions in the literature, especially for high
signal-to-noise ratio (SNR) values.


title: Complex behavior in chains of nonlinear oscillators

abstract:
  This article outlines sufficient conditions under which a one-dimensional
chain of identical nonlinear oscillators can display complex spatio-temporal
behavior. The units are described by phase equations and consist of excitable
oscillators. The interactions are local and the network is poised to a critical
state by balancing excitation and inhibition locally. The results presented
here suggest that in networks composed of many oscillatory units with local
interactions, excitability together with balanced interactions are sufficient
to give rise to complex emergent features. For values of the parameters where
complex behavior occurs, the system also displays a high-dimensional
bifurcation where an exponentially large number of equilibria are borne in
pairs out of multiple saddle-node bifurcations.


title:
Representation Learning with Deconvolution for Multivariate Time Series
  Classification and Visualization

abstract:
  We propose a new model based on the deconvolutional networks and SAX
discretization to learn the representation for multivariate time series.
Deconvolutional networks fully exploit the advantage the powerful
expressiveness of deep neural networks in the manner of unsupervised learning.
We design a network structure specifically to capture the cross-channel
correlation with deconvolution, forcing the pooling operation to perform the
dimension reduction along each position in the individual channel.
Discretization based on Symbolic Aggregate Approximation is applied on the
feature vectors to further extract the bag of features. We show how this
representation and bag of features helps on classification. A full comparison
with the sequence distance based approach is provided to demonstrate the
effectiveness of our approach on the standard datasets. We further build the
Markov matrix from the discretized representation from the deconvolution to
visualize the time series as complex networks, which show more class-specific
statistical properties and clear structures with respect to different labels.


title: Bifurcation Adds Flavor to Basketball

abstract:
  We report an emergence of bifurcation in basketball, a single-particle system
governed by Newtonian mechanics. When shooting the basketball, the obvious
control parameters are the launch speed and the launch angle. We propose to use
the three-dimensional velocity phase-space volume associated with the given
launch parameters to quantify the difficulty of the shooting. The optimal
launch angle that maximizes the associated phase-space volume undergoes a
bifurcation as the launch speed is increased, if the shooter is farther than a
critical distance away from the hoop. Thus, the bifurcation makes it very
important to control the launch speed accurately. If the air resistance is
removed, the bifurcation disappears and the phase-space volume distribution
becomes dispersionless and shrinks in magnitude.


title: Beyond Expansion III: Reciprocal Geodesics

abstract:
  We prove the existence of infinitely many low-lying and fundamental closed
geodesics on the modular surface which are reciprocal, that is, invariant under
time reversal. The method combines ideas from Parts I and II of this series,
namely the dispersion method in bilinear forms, as applied to thin semigroups
coming from restricted continued fractions.


title:
Enhanced entanglement of two different mechanical resonators via
  coherent feedback

abstract:
  It was shown [New J. Phys. 17, 103037 (2015)] that large and robust
entanglement between two different mechanical resonators could be achieved,
either dynamically or in the steady state, in an optomechanical system in which
the two mechanical resonators are coupled to a single cavity mode driven by a
suitably chosen two-tone field. An important limitation of the scheme is that
the cavity decay rate must be much smaller than the two mechanical frequencies
and their difference. Here we show that the entanglement can be remarkably
enhanced, and the validity of the scheme can be largely extended, by adding a
coherent feedback loop that effectively reduces the cavity decay rate.


title: Bayesian Nonparametric Modeling of Heterogeneous Groups of Censored Data

abstract:
  Datasets containing large samples of time-to-event data arising from several
small heterogeneous groups are commonly encountered in statistics. This
presents problems as they cannot be pooled directly due to their heterogeneity
or analyzed individually because of their small sample size. Bayesian
nonparametric modelling approaches can be used to model such datasets given
their ability to flexibly share information across groups. In this paper, we
will compare three popular Bayesian nonparametric methods for modelling the
survival functions of heterogeneous groups. Specifically, we will first compare
the modelling accuracy of the Dirichlet process, the hierarchical Dirichlet
process, and the nested Dirichlet process on simulated datasets of different
sizes, where group survival curves differ in shape or in expectation. We, then,
will compare the models on a real-world injury dataset.


title:
Viscous Hydrodynamics Simulations of Circumbinary Accretion Discs:
  Variability, Quasi-Steady State, and Angular Momentum Transfer

abstract:
  We carry out numerical simulations of circumbinary discs, solving the viscous
hydrodynamics equations on a polar grid covering an extended disc outside the
binary co-orbital region. We use carefully controlled outer boundary conditions
and long-term integrations to ensure that the disc reaches a quasi-steady
state, in which the time-averaged mass accretion rate onto the binary,
$\langle\dot{M}\rangle$, matches the mass supply rate at the outer disc. We
focus on binaries with comparable masses and a wide range of eccentricities
($e_\mathrm{B}$). For $e_\mathrm{B} \lesssim 0.05$, the mass accretion rate of
the binary is modulated at about $5$ times the binary period; otherwise it is
modulated at the binary period. The inner part of the circumbinary disc ($r
\lesssim 6 a_\mathrm{B}$) generally becomes coherently eccentric. For low and
high $e_\mathrm{B}$, the disc line of apsides precesses around the binary, but
for intermediate $e_\mathrm{B}$ ($0.2 - 0.4$), it instead becomes locked with
that of the binary. By considering the balance of angular momentum transport
through the disc by advection, viscous stress, and gravitational torque, we
determine the time-averaged net angular momentum transfer rate to the binary,
$\langle\dot{J}\rangle$. The specific angular momentum, $l_0 =
\langle\dot{J}\rangle/\langle\dot{M}\rangle$, depends non-monotonically on
$e_\mathrm{B}$. Contrary to previous claims, we find that $l_0$ is positive for
most $e_\mathrm{B}$, implying that the binary receives net angular momentum,
which may cause its separation to grow with time. The minimum $l_0$ occurs at
intermediate $e_\mathrm{B}$ ($0.2 - 0.4$), corresponding to the regime where
the inner eccentric disc is apsidally aligned with the binary.


title: Lorentz invariance and the zero-point stress-energy tensor

abstract:
  Some 65 years ago (1951) Wolfgang Pauli noted that the net zero-point energy
density could be set to zero by a carefully fine-tuned cancellation between
bosons and fermions. In the current article I will argue in a slightly
different direction: The zero-point energy density is only one component of the
zero-point stress energy tensor, and it is this tensor quantity that is in many
ways the more fundamental object of interest. I shall demonstrate that Lorentz
invariance of the zero-point stress energy tensor implies finiteness of the
zero-point stress energy tensor, and vice versa. Under certain circumstances,
(in particular, but not limited to, the finite QFTs), Pauli's cancellation
mechanism will survive the introduction of particle interactions. I shall then
relate the discussion to BSM physics, to the cosmological constant, and to
Sakharov-style induced gravity.


title: A Submillimeter Continuum Survey of Local Dust-Obscured Galaxies

abstract:
  We conduct a 350 micron dust continuum emission survey of 17 dust-obscured
galaxies (DOGs) at z = 0.05-0.08 with the Caltech Submillimeter Observatory
(CSO). We detect 14 DOGs with S_350 = 114-650 mJy and S/N > 3. By including two
additional DOGs with submillimeter data in the literature, we are able to study
dust contents for a sample of 16 local DOGs that consists of 12 bump and 4
power-law types. We determine their physical parameters with a two-component
modified blackbody function model. The derived dust temperatures are in the
range 57-122 K and 22-35 K for the warm and cold dust components, respectively.
The total dust mass and the mass fraction of warm dust component are
3-34$\times10^{7} M_\odot$ and 0.03-2.52%, respectively. We compare these
results with those of other submillimeter-detected infrared luminous galaxies.
The bump DOGs, the majority of the DOG sample, show similar distributions of
dust temperatures and total dust mass to the comparison sample. The power-law
DOGs show a hint of smaller dust masses than other samples, but need to be
tested with a larger sample. These findings support that the reason why DOGs
show heavy dust obscuration is not an overall amount of dust content, but
probably the spatial distribution of dust therein.


title: RG flow of entanglement entropy to thermal entropy

abstract:
  Utilizing the holographic technique, we investigate how the entanglement
entropy evolves along the RG flow. After introducing a new generalized
temperature which satisfies the thermodynamics-like law even in the IR regime,
we find that the renormalized entropy and the generalized temperature in the IR
limit approach the thermal entropy and thermodynamic temperature of a real
thermal system. This result implies that the microscopic quantum entanglement
entropy in the IR region leads to the thermodynamic relation up to small
quantum corrections caused by the quantum entanglement near the entangling
surface. Intriguingly, this IR feature of the entanglement entropy universally
happens regardless of the detail of the dual field theory and the shape of the
entangling surface. We check this IR universality with a most general geometry
called the hyperscaling violation geometry which is dual to a relativistic
non-conformal field theory.


title:
Charge Density Wave Phase Transition on the Surface of Electrostatically
  Doped Multilayer Graphene

abstract:
  We demonstrate that charge density wave (CDW) phase transition occurs on the
surface of electronically doped multilayer graphene when the Fermi level
approaches the M points (also known as van Hove singularities where the density
of states diverge) in the Brillouin zone of graphene band structure. The
occurrence of such CDW phase transitions are supported by both the electrical
transport measurement and optical measurements in electrostatically doped
multilayer graphene. The CDW transition is accompanied with the sudden change
of graphene channel resistance at T$_m$= 100K, as well as the splitting of
Raman G peak (1580 cm$^{-1}$). The splitting of Raman G peak indicats the
lifting of in-plane optical phonon branch degeneracy and the non-degenerate
phonon branches are correlated to the lattice reconstructions of graphene --
the CDW phase transition.


title:
The Effect of Modified Gravity on the Odds of the Bound Violations of
  the Turn-Around Radii

abstract:
  The turn-around radii of the galaxy groups show the imprint of a long battle
between their self-gravitational forces and the accelerating space. The
standard $\Lambda$CDM cosmology based on the general relativity (GR) predicts
the existence of an upper bound on the expectation value of the turn-around
radius which is rarely violated by individual galaxy groups. We speculate that
a deviation of the gravitational law from GR on the cosmological scale could
cause an appreciable shift of the mean turn-around radius to higher values and
make the occurrence of the bound violation more probable. Analyzing the data
from high-resolution N-body simulations for two specific models with modified
gravity (MG) and the standard GR+$\Lambda$CDM cosmology, we determine the
turn-around radii of the massive Rockstar groups from the peculiar motions of
the galactic halos located in the bound zone where the fifth force generated by
MG is expected to be at most partially shielded. We detect a $4\sigma$ signal
of difference in the odds of the bound violations between a fiducial MG and the
GR models, proving that the odds of the bound violations increase with the
strength of the fifth force produced by the presence of MG. The advantage of
using the odds of the bound violations as a complementary diagnostics to probe
the nature of gravity is discussed.


title: A Note on Average of Roots of Unity

abstract:
  We consider the problem of characterizing all functions $f$ defined on the
set of integers modulo $n$ with the property that an average of some $n$th
roots of unity determined by $f$ is always an algebraic integer. Examples of
such functions with this property are linear functions. We show that, when $n$
is a prime number, the converse also holds. That is, any function with this
property is representable by a linear polynomial. Finally, we give an
application of the main result to the problem of determining self perfect
isometries for the cyclic group of prime order $p$.


title: On homogeneous hypersurfaces in ${\mathbb C}^3$

abstract:
  We consider a family $M_t^n$, with $n\ge 2$, $t>1$, of real hypersurfaces in
a complex affine $n$-dimensional quadric arising in connection with the
classification of homogeneous compact simply-connected real-analytic
hypersurfaces in ${\mathbb C}^n$ due to Morimoto and Nagano. To finalize their
classification, one needs to resolve the problem of the embeddability of
$M_t^n$ in ${\mathbb C}^n$ for $n=3,7$. In our earlier article we showed that
$M_t^7$ is not embeddable in ${\mathbb C}^7$ for every $t$ and that $M_t^3$ is
embeddable in ${\mathbb C}^3$ for all $1<t<1+10^{-6}$. In the present paper, we
improve on the latter result by showing that the embeddability of $M_t^3$ in
fact takes place for $1<t<\sqrt{(2+\sqrt{2})/3}$. This is achieved by analyzing
the explicit totally real embedding of the sphere $S^3$ in ${\mathbb C}^3$
constructed by Ahern and Rudin. For $t\ge\sqrt{(2+\sqrt{2})/3}$ the problem of
the embeddability of $M_t^3$ remains open.


title:
Evolutionary State-Space Model and Its Application to Time-Frequency
  Analysis of Local Field Potentials

abstract:
  We propose an evolutionary state space model (E-SSM) for analyzing high
dimensional brain signals whose statistical properties evolve over the course
of a non-spatial memory experiment. Under E-SSM, brain signals are modeled as
mixtures of components (e.g., AR(2) process) with oscillatory activity at
pre-defined frequency bands. To account for the potential non-stationarity of
these components (since the brain responses could vary throughout the entire
experiment), the parameters are allowed to vary over epochs. Compared with
classical approaches such as independent component analysis and filtering, the
proposed method accounts for the entire temporal correlation of the components
and accommodates non-stationarity. For inference purpose, we propose a novel
computational algorithm based upon using Kalman smoother, maximum likelihood
and blocked resampling. The E-SSM model is applied to simulation studies and an
application to a multi-epoch local field potentials (LFP) signal data collected
from a non-spatial (olfactory) sequence memory task study. The results confirm
that our method captures the evolution of the power for different components
across different phases in the experiment and identifies clusters of electrodes
that behave similarly with respect to the decomposition of different sources.
These findings suggest that the activity of different electrodes does change
over the course of an experiment in practice, treating these epoch recordings
as realizations of an identical process could lead to misleading results. In
summary, the proposed method underscores the importance of capturing the
evolution in brain responses over the study period.


title: Bridging Neural Machine Translation and Bilingual Dictionaries

abstract:
  Neural Machine Translation (NMT) has become the new state-of-the-art in
several language pairs. However, it remains a challenging problem how to
integrate NMT with a bilingual dictionary which mainly contains words rarely or
never seen in the bilingual training data. In this paper, we propose two
methods to bridge NMT and the bilingual dictionaries. The core idea behind is
to design novel models that transform the bilingual dictionaries into adequate
sentence pairs, so that NMT can distil latent bilingual mappings from the ample
and repetitive phenomena. One method leverages a mixed word/character model and
the other attempts at synthesizing parallel sentences guaranteeing massive
occurrence of the translation lexicon. Extensive experiments demonstrate that
the proposed methods can remarkably improve the translation quality, and most
of the rare words in the test sentences can obtain correct translations if they
are covered by the dictionary.


title:
Encoding Temporal Markov Dynamics in Graph for Visualizing and Mining
  Time Series

abstract:
  Time series and signals are attracting more attention across statistics,
machine learning and pattern recognition as it appears widely in the industry
especially in sensor and IoT related research and applications, but few
advances has been achieved in effective time series visual analytics and
interaction due to its temporal dimensionality and complex dynamics. Inspired
by recent effort on using network metrics to characterize time series for
classification, we present an approach to visualize time series as complex
networks based on the first order Markov process in its temporal ordering. In
contrast to the classical bar charts, line plots and other statistics based
graph, our approach delivers more intuitive visualization that better preserves
both the temporal dependency and frequency structures. It provides a natural
inverse operation to map the graph back to raw signals, making it possible to
use graph statistics to characterize time series for better visual exploration
and statistical analysis. Our experimental results suggest the effectiveness on
various tasks such as pattern discovery and classification on both synthetic
and the real time series and sensor data.


title: Quantum Cluster Superalgebras

abstract:
  In this paper, we introduce and study the quantum deformations of the cluster
superalgebra. Then we prove the quantum version of the Laurent phenomenon for
the super-case.


title:
Hamiltonian Truncation Study of Supersymmetric Quantum Mechanics:
  S-Matrix and Metastable States

abstract:
  We implement the Rayleigh-Ritz method in supersymmetric quantum mechanics
with flat directions, and extract the S-matrix and metastable resonances. The
effectiveness of the method is demonstrated in two strongly coupled systems: an
N=1 toy supermembrane model, and an N=4 model with a U(1) gauge multiplet and a
charged chiral multiplet.


title: Intrusion Alert Prediction Using a Hidden Markov Model

abstract:
  Intrusion detection is only a starting step in securing IT infrastructure.
Prediction of intrusions is the next step to provide an active defense against
incoming attacks. Current intrusion prediction methods focus mainly on
prediction of either intrusion type or intrusion category and do not use or
provide contextual information such as source and target IP address. In
addition most of them are dependant on domain knowledge and specific scenario
knowledge. The proposed algorithm employs a bag-of-words model together with a
hidden Markov model which not depend on specific domain knowledge. Since this
algorithm depends on a training process it is adaptable to different
conditions. A key advantage of the proposed algorithm is the inclusion of
contextual data such as source IP address, destination IP range, alert type and
alert category in its prediction, which is crucial for an eventual response.
Experiments conducted using a public data set generated over 2500 alert
predictions and achieved accuracy of 81% and 77% for single step and five step
predictions respectively for prediction of the next alert cluster. It also
achieved an accuracy of prediction of 95% and 92% for single step and five step
predictions respectively for prediction of the next alert category. The
proposed methods achieved a prediction accuracy improvement of 5% for alert
category over existing variable length Markov chain intrusion prediction
methods, while providing more information for a possible defense.