title: Thermoelectric properties of topological insulator $\mathrm{BaSn_2}$

abstract:
  Recently, $\mathrm{BaSn_2}$ is predicted to be a strong topological insulator
by the first-principle calculations. It is well known that topological
insulator has a close connection to thermoelectric material, such as
$\mathrm{Bi_2Te_3}$ family. In this work, we investigate thermoelectric
properties of $\mathrm{BaSn_2}$ by the first-principles combined with Boltzmann
transport theory. The electronic part is carried out by a modified Becke and
Johnson (mBJ) exchange potential, including spin-orbit coupling (SOC), while
the phonon part is performed using generalized gradient approximation (GGA). It
is found that the electronic transport coefficients between the in-plane and
cross-plane directions show the strong anisotropy, while lattice lattice
thermal conductivities show an almost isotropy. Calculated results show a very
low lattice thermal conductivity for $\mathrm{BaSn_2}$, and the corresponding
average lattice thermal conductivity at room temperature is 1.69 $\mathrm{W
m^{-1} K^{-1}}$, which is comparable or lower than those of lead chalcogenides
and bismuth-tellurium systems as classic thermoelectric materials. Due to the
complicated scattering mechanism, calculating scattering time $\tau$ is
challenging. By using a empirical $\tau$=$10^{-14}$ s, the n-type figure of
merit $ZT$ is greater than 0.40 in wide temperature range. Experimentally, it
is possible to attain better thermoelectric performance, or to enhance one by
strain or tuning size parameter. This work indicates that $\mathrm{BaSn_2}$ may
be a potential thermoelectric material, which can stimulate further theoretical
and experimental works.


title: Methodical Fitting for Mathematical Models of Rubber-like Materials

abstract:
  A great variety of models can describe the non-linear response of rubber to
uni-axial tension. Yet an in-depth understanding of the successive stages of
large extension is still lacking. We show that the response can be broken down
in three steps, which we delineate by relying on a simple formatting of the
data, the so-called Mooney transform. First, the small-to-moderate regime,
where the polymeric chains unfold easily and the Mooney plot is almost linear.
Second, the strain-hardening regime, where blobs of bundled chains unfold to
stiffen the response in correspondence to the "upturn" of the Mooney plot.
Third, the limiting-chain regime, with a sharp stiffening occurring as the
chains extend towards their limit. We provide strain-energy functions with
terms accounting for each stage, that (i) give an accurate local and then
global fitting of the data; (ii) are consistent with weak non-linear elasticity
theory; and (iii) can be interpreted in the framework of statistical mechanics.
We apply our method to Treloar's classical experimental data and also to some
more recent data. Our method not only provides models that describe the
experimental data with a very low quantitative relative error, but also shows
that the theory of non-linear elasticity is much more robust that seemed at
first sight.


title: Stochastic quantum Zeno-based detection of noise correlations

abstract:
  A system under constant observation is practically freezed to the measurement
subspace. If the system driving is a random classical field, the survival
probability of the system in the subspace becomes a random variable described
by the Stochastic Quantum Zeno Dynamics (SQZD) formalism. Here, we study the
time and ensemble average of this random survival probability and demonstrate
how time correlations in the noisy environment determine whether the two
averages do coincide or not. These environment time correlations can
potentially generate non-Markovian dynamics of the quantum system depending on
the structure and energy scale of the system Hamiltonian. We thus propose a way
to probe this interesting property of the environment by means of the system
survival probability. This will further contribute to the development of new
schemes for quantum sensing technologies, where nanodevices may be exploited to
image external structures or biological molecules via the surface field they
generate.


title:
Asteroseismology of 1523 misclassified red giants using
  $\textit{Kepler}$ data

abstract:
  We analysed solar-like oscillations in 1523 $\textit{Kepler}$ red giants
which have previously been misclassified as subgiants, with predicted $\nu_{\rm
max}$ values (based on the Kepler Input Catalogue) between 280$\mu$Hz to
700$\mu$Hz. We report the discovery of 626 new oscillating red giants in our
sample, in addition to 897 oscillators that were previously characterized by
Hekker et al. (2011) from one quarter of $\textit{Kepler}$ data. Our sample
increases the known number of oscillating low-luminosity red giants by $26\%$
(up to $\sim$ 1900 stars). About three quarters of our sample are classified as
ascending red-giant-branch stars, while the remainder are red-clump stars. A
novel scheme was applied to determine $\Delta \nu$ for 108 stars with $\nu_{\rm
max}$ close to the Nyquist frequency (240$\mu$Hz < $\nu_{\rm max}$ <
320$\mu$Hz). Additionally, we identified 47 stars oscillating in the
super-Nyquist frequency regime, up to 387$\mu$Hz, using long-cadence light
curves. We show that the misclassifications are most likely due to large
uncertainties in KIC surface gravities, and do not result from the absence of
broadband colors or from different physical properties such as reddening,
spatial distribution, mass or metallicity. The sample will be valuable to study
oscillations in low-luminosity red giants and to characterize planet candidates
around those stars.


title:
Enantiodromic effective generators of a Markov jump process with
  Gallavotti-Cohen symmetry

abstract:
  This paper deals with the properties of the stochastic generators of the
effective (driven) processes associated with atypical values of
transition-dependent time-integrated currents with Gallavotti-Cohen symmetry in
Markov jump processes. Exploiting the concept of biased ensemble of
trajectories by introducing a biasing field $s$, we show that the stochastic
generators of the effective processes associated with the biasing fields $s$
and $E-s$ are enantiodromic with respect to each other where $E$ is the
conjugated field to the current. We illustrate our findings by considering an
exactly solvable creation-annihilation process of classical particles with
nearest-neighbor interactions defined on a one-dimensional lattice.


title: Dynamic particle packing in freezing colloidal suspensions

abstract:
  In the field of freezing colloidal suspensions, it is important to understand
the particle-scale behavior of particle packing. Here, we reveal the dynamics
of particle packing by identifying the behavior of each single particle in
situ. The typical pattern consists of locally ordered clusters and amorphous
defects. The microscopic mechanism of pattern formation is ascribed to the
non-equilibrium particle-packing process on the particle scale, described with
the P\'eclet number. The macroscopic migration of a particle layer is also
revealed by an analytical model involving parameters of freezing speed and
initial volume fraction of particles.


title: Reweighting with Boosted Decision Trees

abstract:
  Machine learning tools are commonly used in modern high energy physics (HEP)
experiments. Different models, such as boosted decision trees (BDT) and
artificial neural networks (ANN), are widely used in analyses and even in the
software triggers.
  In most cases, these are classification models used to select the "signal"
events from data. Monte Carlo simulated events typically take part in training
of these models. While the results of the simulation are expected to be close
to real data, in practical cases there is notable disagreement between
simulated and observed data. In order to use available simulation in training,
corrections must be introduced to generated data. One common approach is
reweighting - assigning weights to the simulated events. We present a novel
method of event reweighting based on boosted decision trees. The problem of
checking the quality of reweighting step in analyses is also discussed.


title: Recovery of $L^p$-potential in the plane

abstract:
  An inverse problem for the two-dimensional Schrodinger equation with
$L^p_{com}$-potential, $p>1$, is considered. Using the
$\overline{\partial}$-method, the potential is recovered from the
Dirichlet-to-Neumann map on the boundary of a domain containing the support of
the potential. We do not assume that the potential is small or that the Faddeev
scattering problem does not have exceptional points. The paper contains a new
estimate on the Faddeev Green function that immediately implies the absence of
exceptional points near the origin and infinity when $v\in L^p_{com}$.


title:
Relativistic nature of carriers: Origin of electron-hole conduction
  asymmetry in m o n o l a ye r gr a p h e n e

abstract:
  We report electron-hole conduction asymmetry in monolayer graphene.
Previously, it has been claimed that electron-hole conduction asymmetry is due
to imbalanced carrier injection from metallic electrodes. Here, we show that
metallic contacts have negligible impact on asymmetric conduction and may be
either sample or device-dependent phenomena. Electrical measurements show that
monolayer graphene based devices exhibit suppressed electron conduction
compared to hole conduction due to the presence of donor impurities which
scatter electrons more efficiently. This can be explained by the relativistic
nature of charge carriers in a graphene monolayer and can be reconciled with
the fact that in a relativistic quantum system transport cross section does
depend on the sign of scattering potential in contrast to a nonrelativistic
quantum system.


title: Metric Measure Space as a Framework for Gravitation

abstract:
  In this manuscript, we show how conformal invariance can be incorporated in a
classical theory of gravitation, in the context of metric measure space. Metric
measure space involves a geometrical scalar $f$, dubbed as density function,
which here appears as a conformal degree of freedom. In this framework, we
present conformally invariant field equations, the relevant identities and
geodesic equations. In metric measure space, the volume element and accordingly
the operators with integral based definitions are modified. For instance, the
divergence operator in this space differs from the Riemannian one. As a result,
a gravitational theory formulated in this space has a generalized second
Bianchi identity and a generalized conservation of energy-momentum tensor. It
is shown how, by using the generalized identity for conservation of
energy-momentum tensor, one can obtain a conformally invariant geodesic
equation. By comparison of the geodesic equations in metric measure space with
the Bohmian trajectories, in both relativistic and non-relativistic regimes, a
relation between density function $f$ and the quantum potential is proposed.
This suggests metric measure space to be considered as a suitable framework for
geometric description of Bohm's quantum mechanics. On the other hand, as it is
known, Weyl geometry is one of the main approaches to construct conformally
invariant gravitational models. Regarding the fact that the connection in the
integrable Weyl space is modified and in metric measure space remains the same
as it is in the Riemann space, the mathematical analogy between these two
spaces is also discussed.


title: Unifying Markov Properties for Graphical Models

abstract:
  Several types of graphs with different conditional independence
interpretations --- also known as Markov properties --- have been proposed and
used in graphical models. In this paper we unify these Markov properties by
introducing a class of graphs with four types of edges --- lines, arrows, arcs,
and dotted lines --- and a single separation criterion. We show that
independence structures defined by this class specialize to each of the
previously defined cases, when suitable subclasses of graphs are considered. In
addition, we define a pairwise Markov property for the subclass of chain mixed
graphs which includes chain graphs with the LWF interpretation, as well as
summary graphs (and consequently ancestral graphs). We prove the equivalence of
this pairwise Markov property to the global Markov property for compositional
graphoid independence models.


title:
On bipartite unitary matrices generating subalgebra-preserving quantum
  operations

abstract:
  We study the structure of bipartite unitary operators which generate via the
Stinespring dilation theorem, quantum operations preserving some given matrix
algebra, independently of the ancilla state. We characterize completely the
unitary operators preserving diagonal, block-diagonal, and tensor product
algebras. Some unexpected connections with the theory of quantum Latin squares
are explored, and we introduce and study a Sinkhorn-like algorithm used to
randomly generate quantum Latin squares.


title:
Analysis of Bayesian Classification based Approaches for Android Malware
  Detection

abstract:
  Mobile malware has been growing in scale and complexity spurred by the
unabated uptake of smartphones worldwide. Android is fast becoming the most
popular mobile platform resulting in sharp increase in malware targeting the
platform. Additionally, Android malware is evolving rapidly to evade detection
by traditional signature-based scanning. Despite current detection measures in
place, timely discovery of new malware is still a critical issue. This calls
for novel approaches to mitigate the growing threat of zero-day Android
malware. Hence, in this paper we develop and analyze proactive Machine Learning
approaches based on Bayesian classification aimed at uncovering unknown Android
malware via static analysis. The study, which is based on a large malware
sample set of majority of the existing families, demonstrates detection
capabilities with high accuracy. Empirical results and comparative analysis are
presented offering useful insight towards development of effective
static-analytic Bayesian classification based solutions for detecting unknown
Android malware.


title: phi-LSTM: A Phrase-based Hierarchical LSTM Model for Image Captioning

abstract:
  A picture is worth a thousand words. Not until recently, however, we noticed
some success stories in understanding of visual scenes: a model that is able to
detect/name objects, describe their attributes, and recognize their
relationships/interactions. In this paper, we propose a phrase-based
hierarchical Long Short-Term Memory (phi-LSTM) model to generate image
description. The proposed model encodes sentence as a sequence of combination
of phrases and words, instead of a sequence of words alone as in those
conventional solutions. The two levels of this model are dedicated to i) learn
to generate image relevant noun phrases, and ii) produce appropriate image
description from the phrases and other words in the corpus. Adopting a
convolutional neural network to learn image features and the LSTM to learn the
word sequence in a sentence, the proposed model has shown better or competitive
results in comparison to the state-of-the-art models on Flickr8k and Flickr30k
datasets.


title:
Stochastic Evolution Equations in Banach Spaces and Applications to
  Heath-Jarrow-Morton-Musiela Equation

abstract:
  In this paper we study the stochastic evolution equation (1.1) in
martingale-type 2 Banach spaces (with the linear part of the drift being only a
generator of a C0-semigroup). We prove the existence and the uniqueness of
solutions to this equation. We apply the abstract results to the
Heath-Jarrow-Morton-Musiela (HJMM) equation (6.3). In particular, we prove the
existence and the uniqueness of solutions to the latter equation in the
weighted Lebesgue and Sobolev spaces respectively. We also find a sufficient
condition for the existence and the uniqueness of an invariant measure for the
Markov semigroup associated to equation (6.3) in the weighted Lebesgue spaces.


title:
An approach for finding fully Bayesian optimal designs using
  normal-based approximations to loss functions

abstract:
  The generation of decision-theoretic Bayesian optimal designs is complicated
by the significant computational challenge of minimising an analytically
intractable expected loss function over a, potentially, high-dimensional design
space. A new general approach for approximately finding Bayesian optimal
designs is proposed which uses computationally efficient normal-based
approximations to posterior summaries to aid in approximating the expected
loss. This new approach is demonstrated on illustrative, yet challenging,
examples including hierarchical models for blocked experiments, and
experimental aims of parameter estimation and model discrimination. Where
possible, the results of the proposed methodology are compared, both in terms
of performance and computing time, to results from using computationally more
expensive, but potentially more accurate, Monte Carlo approximations. Moreover
the methodology is also applied to problems where the use of Monte Carlo
approximations is computationally infeasible.


title: Linear Kernels for Separating a Graph into Components of Bounded Size

abstract:
  Graph separation and partitioning are fundamental problems that have been
extensively studied both in theory and practice. The \textsc{$p$-Size
Separator} problem, closely related to the \textsc{Balanced Separator} problem,
is to check whether we can delete at most $k$ vertices in a given graph $G$
such that each connected component of the remaining graph has at most $p$
vertices. This problem is NP-hard for each fixed integer $p\geq 1$ and it
becomes the famous \textsc{Vertex Cover} problem when $p=1$. It is known that
the problem with parameter $k$ is W[1]-hard for unfixed $p$. In this paper, we
prove a kernel of $O(pk)$ vertices for this problem, i.e., a linear vertex
kernel for each fixed $p \geq 1$. In fact, we first obtain an $O(p^2k)$ vertex
kernel by using a nontrivial extension of the expansion lemma. Then we further
reduce the kernel size to $O(pk)$ by using some `local adjustment' techniques.
Our proofs are based on extremal combinatorial arguments and the main result
can be regarded as a generalization of the Nemhauser and Trotter's theorem for
the \textsc{Vertex Cover} problem. These techniques are possible to be used to
improve kernel sizes for more problems, especially problems with kernelization
algorithms based on techniques similar to the expansion lemma or crown
decompositions.


title:
Understanding molecular harmonic emission at relatively long intense
  laser pulses: Beyond the Born-Oppenheimer approximation

abstract:
  The underlying physics behind the molecular harmonic emission in relatively
long sin$^2$-like laser pulses is investigated. We numerically solved the
full-dimensional electronic time-dependent Schr\"{o}dinger equation beyond the
Born-Oppenheimer approximation for simple molecular ion H$_2^+$. The occurrence
and the effect of electron localization, non-adiabatic redshift and spatially
asymmetric emission are evaluated to understand better complex patterns
appearing in the high-order harmonic generation (HHG) spectrum.
  Results show that the complex patterns in the HHG spectrum originate mainly
from a non-adiabatic response of the molecule to the rapidly changing laser
field and also from a spatially asymmetric emission along the polarization
direction. The effect of electron localization on the HHG spectrum was not
observed as opposed to what is reported in the literature.


title: Semi-geostrophic System with Variable Coriolis parameter

abstract:
  We prove short time existence and uniqueness of smooth solutions ( in
$C^{k+2,\alpha}$ with $k\geq 2$) to the 2-D semi-geostrophic system and
semi-geostrophic shallow water system with variable Coriolis parameter $f$ and
periodic boundary conditions, under the natural convexity condition on the
initial data. The dual space used in analysis of the semi-geostrophic system
with constant $f$ does not exist for the variable Coriolis parameter case, and
we develop a time-stepping procedure to overcome this difficulty.


title:
Generalized Galilean transformations of tensors and cotensors with
  application to general fluid motion

abstract:
  Galilean transformation properties of different physical quantities are
investigated from the point of view of four dimensional Galilean relativistic
(non-relativistic) space-time. The objectivity of balance equations of general
heat conducting fluids and of the related physical quantities is treated as an
application.


title:
Generalized Vandermonde Determinants and Characterization of
  Divisibility Sequences

abstract:
  We present a different proof of the characterization of non--degenerate
recurrence sequences, which are also divisibility sequences, given by Van der
Poorten, Bezevin, and Petho in their paper "A Full Characterisation of
Divisibility Sequence". Our proof is based on an interesting determinant
identity related to impulse sequences, arising from the evaluation of a
generalized Vandermonde determinant. As a consequence of this new proof we can
find a more precise form for the resultant sequence presented in their paper,
in the general case of non--degenerate divisibility sequences having minimal
polynomial with multiple roots.


title: A distance expanding flow on exact Lagrangian cobordism classes

abstract:
  Given an exact Lagrangian $L$ of an exact symplectic manifold $(M,d\lambda
)$, Cornea and Shelukhin recently introduced a remarkable "cobordism metric"
$d_c$ on the exact Lagrangian cobordism class $\mathcal{L}(L)$ of $L$. In this
note we show that the Liouville flow of $(M,d\lambda )$ induces a flow on
$(\mathcal{L}(L),d_c)$ which expands cobordism distances. In particular we
deduce that $(\mathcal{L}(L),d_c)$ has infinite diameter whenever the Liouville
flow is complete. We also discuss (Hamiltonian and Lagrangian) Hofer-geometric
versions of our result. The proof only uses elementary differential geometry.


title: A rigorous treatment of moist convection in a single column

abstract:
  We study a single column model of moist convection in the atmosphere. We
state the conditions for it to represent a stable steady state. We then evolve
the column by subjecting it to an upward displacement which can release
instability, leading to a time dependent sequence of stable steady states. We
propose a definition of measure valued solution to describe the time dependence
and prove its existence.


title:
Low-temperature behavior of transmission phase shift across a Kondo
  correlated quantum dot

abstract:
  We study the transmission phase shift across a Kondo correlated quantum dot
in a GaAs heterostructure at temperatures below the Kondo temperature ($T <
T_{\rm K}$), where the phase shift is expected to show a plateau at $\pi/2$ for
an ideal Kondo singlet ground state. Our device is tuned such that the ratio
$\Gamma/U$ of level width $\Gamma$ to charging energy $U$ is quite large
($\lesssim 0.5$ rather than $\ll 1$). This situation is commonly used in GaAs
quantum dots to ensure Kondo temperatures large enough ($\simeq 100$ mK here)
to be experimentally accessible; however it also implies that charge
fluctuations are more pronounced than typically assumed in theoretical studies
focusing on the regime $\Gamma/U \ll 1$ needed to ensure a well-defined local
moment. Our measured phase evolves monotonically by $\pi$ across the two
Coulomb peaks, but without being locked at $\pi/2$ in the Kondo valley for $T
\ll T_{\rm K}$, due to a significant influence of large $\Gamma/U$. Only when
$\Gamma/U$ is reduced sufficiently does the phase start to be locked around
$\pi/2$ and develops into a plateau at $\pi/2$. Our observations are consistent
with numerical renormalization group calculations, and can be understood as a
direct consequence of the Friedel sum rule that relates the transmission phase
shift to the local occupancy of the dot, and thermal average of a transmission
coefficient through a resonance level near the Fermi energy.


title: Phyllotaxis, disk packing and Fibonacci numbers

abstract:
  We consider the evolution of the packing of disks (representing the position
of buds) that are introduced at the top of a surface which has the form of a
growing stem. They migrate downwards, while conforming to three principles,
applied locally: dense packing, homogeneity and continuity. We show that spiral
structures characterised by the widely observed Fibonacci sequence
(1,1,2,3,5,8,13...), as well as related structures, occur naturally under such
rules. Typical results are presented in a animation.


title:
Superconductivity-Induced Ferromagnetism and Weyl Superconductivity in
  Nb-doped Bi$_2$Se$_3$

abstract:
  A recent experiment on Nb-doped Bi2Se3 showed that zero field magnetization
appears below the superconducting transition temperature. This gives evidence
that the superconducting state breaks time-reversal symmetry spontaneously and
possibly be in the chiral topological phase. This is in sharp contrast to the
Cu-doped case which is possibly in the nematic phase and breaks rotational
symmetry spontaneously. By deriving the free energy of the system from a
microscopic model, we show that the magnetic moments of the Nb atoms can be
polarized by the chiral Cooper pairs and enlarge the phase space of the chiral
topological phase compared to the nematic phase. We further show that the
chiral topological phase is a Weyl superconducting phase with bulk nodal points
which are connected by surface Majorana arcs.


title: The Quantum Steeplechase

abstract:
  Quantum Steeplechase is the study of a Luttinger liquid (LL) in one dimension
in the presence of a finite number of barriers and wells clustered around an
origin. The powerful non-chiral bosonization technique (NCBT) is introduced to
write down closed formulas for the two-point functions in the sense of the
random phase approximation (RPA). Unlike g-ology based methods that are tied to
the translationally invariant, free particle basis, the NCBT explicitly makes
use of the translationally non-invariant single particle wavefunctions. The
present method that provides the most singular part of the asymptotically exact
Green function in a closed form, is in contrast to competing methods that
require a combination of renormalization group and/or numerical methods in
addition to the bosonization techniques.


title: Formation of sand ripples under a turbulent liquid flow

abstract:
  Sand ripples are commonly observed in both nature and industry. For example,
they are found on riverbeds and in oil pipelines that transport sand. In both
natural and industrial cases, ripples increase friction between the bed and
fluid and are related to flooding, high pressure drops, and transients. Ripples
appear when sediments are entrained as bed load (a mobile granular layer) and
are usually considered to be the result of initial bedforms that eventually
saturate. Given the small aspect ratio of the initial bedforms, linear analyses
can be used to understand the formation of ripples. This paper presents a
linear stability analysis of a granular bed under a turbulent flow of a liquid.
This analysis takes into consideration all the main mechanisms and parameters
involved in the turbulent liquid case, including some important parameters that
have not yet been considered together such as the bed compactness and the
bed-load threshold shear stress. The results of this analysis are compared with
published experimental results and they show good agreement.


title: A new restriction for initially stressed elastic solids

abstract:
  We introduce a fundamental restriction on the strain energy function and
stress tensor for initially stressed elastic solids. The restriction applies to
strain energy functions $W$ that are explicit functions of the elastic
deformation gradient $\mathbf{F}$ and initial stress $\boldsymbol \tau$, i.e.
$W:= W(\mathbf F, \boldsymbol \tau)$. The restriction is a consequence of
energy conservation and ensures that the predicted stress and strain energy do
not depend upon an arbitrary choice of reference configuration. We call this
restriction: initial stress reference independence (ISRI). It transpires that
almost all strain energy functions found in the literature do not satisfy ISRI,
and may therefore lead to unphysical behaviour, which we illustrate via a
simple example. To remedy this shortcoming we derive three strain energy
functions that do satisfy the restriction. We also show that using initial
strain (often from a virtual configuration) to model initial stress leads to
strain energy functions that automatically satisfy ISRI. Finally, we reach the
following important result: ISRI reduces the number of unknowns of the linear
stress tensor of initially stressed solids. This new way of reducing the linear
stress may open new pathways for the non-destructive determination of initial
stresses via ultrasonic experiments, among others.


title: Chance constraint based multi agent navigation under uncertainty

abstract:
  We present Probabilistic Reciprocal Velocity Obstacle or PRVO as a general
algorithm for navigating multiple robots under perception and motion
uncertainty. PRVO is defined as the space of velocities that ensures dynamic
collision avoidance between a pair of robots with a specified probability. Our
approach is based on defining chance constraints over the inequalities defined
by the deterministic Reciprocal Velocity Obstacle (RVO). The computational
complexity of the proposed probabilistic RVO is comparable to the deterministic
counterpart. This is achieved by a series of reformulations where we first
substitute the computationally intractable chance constraints with a family of
surrogate constraints and then adopt a time scaling based solution methodology
to efficiently characterize their solution space. Further, we also show that
the solution space of each member of the family of surrogate constraints can be
mapped in closed form to the probability with which the original chance
constraints are satisfied and thus consequently to probability of collision
avoidance. We validate our formulations through numerical simulations where we
highlight the importance of incorporating the effect of motion uncertainty and
the advantages of PRVO over existing formulations which handles the effect of
uncertainty by using conservative bounding volumes.


title: DEBH: Detection and Elimination Black Holes in Mobile Ad Hoc Network

abstract:
  Security in Mobile Ad hoc Network (MANET) is one of the key challenges due to
its special features e.g. hop-by-hop communications, dynamic topology, and open
network boundary that received tremendous attention by scholars. Traditional
security methods are not applicable in MANET due to its special properties. In
this paper, a novel approach called Detecting and Eliminating Black Holes
(DEBH) is proposed that uses a data control packet and an additional Black hole
Check (BCh) table for detecting and eliminating malicious nodes. Benefiting
from trustable nodes, the processing overhead of the security method decreases
by passing time. Ad hoc On-demand Distance Vector (AODV) routing protocol is
used as the routing protocol in our design. After finding the freshest path
using AODV, our design checks the safety of selected path. In case of detecting
any malicious node, it is isolated from the entire network by broadcasting a
packet that contains the ID of malicious nodes. Simulation results show that
DEBH increases network throughput and decreases packet overhead and delay in
comparison with other studied approaches. Moreover, DEBH is able to detect all
active malicious nodes which generates fault routing information.


title: Theory of chirped photonic crystals in biological broadband reflectors

abstract:
  One-dimensional photonic crystals with slowly varying, i.e. "chirped",
lattice period are responsible for broadband light reflectance in many diverse
biological contexts, ranging from the shiny coatings of various beetles to the
eyes of certain butterflies. We present a quantum scattering analogy for light
reflection from these adiabatically chirped photonic crystals (ACPCs) and apply
a WKB-type approximation to obtain a closed-form expression for the
reflectance. From this expression we infer several design principles, including
a differential equation for the chirp pattern required to elicit a given
reflectance spectrum and the minimal number of bilayers required to exceed a
desired reflectance threshold. Comparison of the number of bilayers found in
ACPCs throughout nature and our predicted minimal required number also gives a
quantitative measure of the optimality of chirped biological reflectors.
Together these results elucidate the design principles of chirped reflectors in
nature and their possible application to future optical technologies.


title: Chaos in DNA Evolution

abstract:
  In this paper, we explain why the chaotic model (CM) of Bahi and Michel
(2008) accurately simulates gene mutations over time. First, we demonstrate
that the CM model is a truly chaotic one, as defined by Devaney. Then, we show
that mutations occurring in gene mutations have the same chaotic dynamic, thus
making the use of chaotic models relevant for genome evolution.


title:
CO-Induced Restructuring on Stepped Pt Surfaces: A Molecular Dynamics
  Study

abstract:
  The effects of plateau width and step edge kinking on carbon monoxide
(CO)-induced restructuring of platinum surfaces were explored using molecular
dynamics (MD) simulations. Platinum crystals displaying four different vicinal
surfaces [(321), (765), (112), and (557)] were constructed and exposed to
partial coverages of carbon monoxide. Platinum-CO interactions were fit to
recent experimental data and density functional theory (DFT) calculations,
providing a classical interaction model that captures the atop binding
preference on Pt. The differences in Pt-Pt binding strength between edge atoms
on the various facets were found to play a significant role in step edge
wandering and reconstruction events. Because the mechanism for step doubling
relies on a stochastic meeting of two wandering edges, the widths of the
plateaus on the original surfaces was also found to play a role in these
reconstructions. On the Pt(321) surfaces, the CO adsorbate was found to assist
in reordering the kinked step edges into straight {100} edge segments.


title:
Magnetism and Spin Transport of Carbon Chain between Armchair Graphene
  Nanoribbon electrodes

abstract:
  The magnetic and spin transport properties of a carbon chain between two
armchair graphene nanoribbon (AGNR) electrodes were studied using tight-binding
Hamiltonian, mean-field Hubbard model and Landauer-Butikker formalism. The
results showed that only odd-numbered carbon chains show intrinsic magnetic
moments in chain-graphene junctions. It was also found that the electronic,
magnetic and spin transport properties of carbon chain-graphene junctions
strongly depend on the position and the length of the carbon chains between
AGNR electrodes. Interestingly, we found a fully spin-polarized transmission
near the Fermi energy in all odd-numbered carbon chain-graphene junctions,
regardless of their lengths and without any magnetic field and magnetic
electrodes.


title: On flat epimorphisms of rings and pointwise localizations

abstract:
  In this paper all rings are commutative. We prove some new results on flat
epimorphisms of rings and pointwise localizations. Especially among them, it is
proved that a ring $R$ is an absolutely flat (von-Neumann regular) ring if and
only if it is isomorphic to the pointwise localization $R^{(-1)}R$, or
equivalently, each $R-$algebra is $R-$flat. For a given minimal prime ideal
$\mathfrak{p}$ of a ring $R$, the surjectivity of the canonical map
$R\rightarrow R_{\mathfrak{p}}$ is characterized. Finally, we give a new proof
to the fact that in a flat epimorphism of rings, the contraction-extension of
an ideal equals the same ideal.


title: Multivariate Delta Goncarov and Abel Polynomials

abstract:
  Classical Gon\v{c}arov polynomials are polynomials which interpolate
derivatives. Delta Gon\v{c}arov polynomials are polynomials which interpolate
delta operators, e.g., forward and backward difference operators. We extend
fundamental aspects of the theory of classical bivariate Gon\v{c}arov
polynomials and univariate delta Gon\v{c}arov polynomials to the multivariate
setting using umbral calculus. After introducing systems of delta operators, we
define multivariate delta Gon\v{c}arov polynomials, show that the associated
interpolation problem is always solvable, and derive a generating function (an
Appell relation) for them. We show that systems of delta Gon\v{c}arov
polynomials on an interpolation grid $Z \subseteq \mathbb{R}^d$ are of binomial
type if and only if $Z = A\mathbb{N}^d$ for some $d\times d$ matrix $A$. This
motivates our definition of delta Abel polynomials to be exactly those delta
Gon\v{c}arov polynomials which are based on such a grid. Finally, compact
formulas for delta Abel polynomials in all dimensions are given for separable
systems of delta operators. This recovers a former result for classical
bivariate Abel polynomials and extends previous partial results for classical
trivariate Abel polynomials to all dimensions.


title: Giant Magnetoresistance in Bilayer Graphene Nanoflakes

abstract:
  Coherent spin transport through bilayer graphene (BLG) nanoflakes sandwiched
between two electrodes made of single-layer zigzag graphene nanoribbon was
investigated by means of Landauer-Buttiker formalism. Application of a magnetic
field only on BLG structure as a channel produces a perfect spin polarization
in a large energy region. Moreover, the conductance could be strongly modulated
by magnetization of the zigzag edge of AB-stacked BLG, and the junction,
entirely made of carbon, produces a giant magnetoresistance (GMR) up to
$10^6\%$. Intestinally, GMR and spin polarization could be tuned by varying BLG
width and length. Generally, MR in a AB-stacked BLG strongly increases
(decreases) with length (width).


title: Proving chaotic behaviour of CBC mode of operation

abstract:
  The cipher block chaining (CBC) block cipher mode of operation was invented
by IBM (International Business Machine) in 1976. It presents a very popular way
of encrypting which is used in various applications. In this paper, we have
mathematically proven that, under some conditions, the CBC mode of operation
can admit a chaotic behaviour according to Devaney. Some cases will be properly
studied in order to put in evidence this idea.


title: Computation Offloading Decisions for Reducing Completion Time

abstract:
  We analyze the conditions in which offloading computation reduces completion
time. We extend the existing literature by deriving an inequality (Eq. 4) that
relates computation offloading system parameters to the bits per instruction
ratio of a computational job. This ratio is the inverse of the arithmetic
intensity. We then discuss how this inequality can be used to determine the
computations that can benefit from offloading as well as the computation
offloading systems required to make offloading beneficial for particular
computations.


title:
Displacement and annihilation of Dirac gap-nodes in d-wave iron-based
  superconductors

abstract:
  Several experimental and theoretical arguments have been made in favor of a
$d-$wave symmetry for the superconducting state in some Fe-based materials. It
is a common belief that a $d-$wave gap in the Fe-based superconductors must
have nodes on the Fermi surfaces centered at the $\Gamma$ point of the
Brillouin zone. Here we show that, while this is the case for a single Fermi
surface made out of a single orbital, the situation is more complex if there is
an even number of Fermi surfaces made out of different orbitals. In particular,
we show that for the two $\Gamma$-centered hole Fermi surfaces made out of
$d_{xz}$ and $d_{yz}$ orbitals, the nodal points still exist near $T_{c}$ along
the symmetry-imposed directions, but are are displaced to momenta between the
two Fermi surfaces. If the two hole pockets are close enough, pairs of nodal
points can merge and annihilate at some $T<T_{c}$, making the $d-$wave state
completely nodeless. These results imply that photoemission evidence for a
nodeless gap on the $d_{xz}/d_{yz}$ Fermi surfaces of KFe$_{2}$As$_{2}$ does
not rule out $d-$wave gap symmetry in this material, while a nodeless gap
observed on the $d_{xy}$ pocket in K$_{x}$Fe$_{2-y}$Se$_{2}$ is truly
inconsistent with the $d-$wave gap symmetry.


title:
Enhancement of Rashba spin-orbit coupling by electron-electron
  interaction

abstract:
  We studied how the electron-electron (e-e) interaction enhances the strength
of the Rashba spin-orbit coupling (RSOC) and opens the possibility of
generating a spin-polarized output current from an unpolarized electric current
without any magnetic elements. In this regard, we proposed a novel design of a
graphene-like junction based on the $e$-$e$ interaction and the $RSOC$. The
results showed that the $e$-$e$ interaction with $RSOC$ opens a spin energy gap
and extremely enhances the $RSOC$ in this spin energy gap. Interestingly, the
junction produces a large spin-polarized current and could act as a
high-efficiency spin filter device (nearly 100\% spin polarization) at room
temperature even at low Rashba and e-e interaction strengths. However, with an
appropriate design, we showed that RSOC could strongly weaken the
spin-polarized current and the spin energy gap, which is solely produced by the
$e$-$e$ interaction, but a high spin polarization persists in some energy
ranges.


title:
Back to Basics: Unsupervised Learning of Optical Flow via Brightness
  Constancy and Motion Smoothness

abstract:
  Recently, convolutional networks (convnets) have proven useful for predicting
optical flow. Much of this success is predicated on the availability of large
datasets that require expensive and involved data acquisition and laborious la-
beling. To bypass these challenges, we propose an unsuper- vised approach
(i.e., without leveraging groundtruth flow) to train a convnet end-to-end for
predicting optical flow be- tween two images. We use a loss function that
combines a data term that measures photometric constancy over time with a
spatial term that models the expected variation of flow across the image.
Together these losses form a proxy measure for losses based on the groundtruth
flow. Empiri- cally, we show that a strong convnet baseline trained with the
proposed unsupervised approach outperforms the same network trained with
supervision on the KITTI dataset.


title: Glauber theory and the quantum coherence of curvature inhomogeneities

abstract:
  The curvature inhomogeneities are systematically scrutinized in the framework
of the Glauber approach. The amplified quantum fluctuations of the scalar and
tensor modes of the geometry are shown to be first-order coherent while the
interference of the corresponding intensities is larger than in the case of
Bose-Einstein correlations. After showing that the degree of second-order
coherence does not suffice to characterize unambiguously the curvature
inhomogeneities, we argue that direct analyses of the degrees of third and
fourth-order coherence are necessary to discriminate between different
correlated states and to infer more reliably the statistical properties of the
large-scale fluctuations. We speculate that the moments of the multiplicity
distributions of the relic phonons might be observationally accessible thanks
to new generations of instruments able to count the single photons of the
Cosmic Microwave Background in the THz region.

categories: hep-th astro-ph.CO gr-qc hep-ph quant-ph


title:
Resiliency in Distributed Sensor Networks for PHM of the Monitoring
  Targets

abstract:
  In condition-based maintenance, real-time observations are crucial for
on-line health assessment. When the monitoring system is a wireless sensor
network, data loss becomes highly probable and this affects the quality of the
remaining useful life prediction. In this paper, we present a fully distributed
algorithm that ensures fault tolerance and recovers data loss in wireless
sensor networks. We first theoretically analyze the algorithm and give
correctness proofs, then provide simulation results and show that the algorithm
is (i) able to ensure data recovery with a low failure rate and (ii) preserves
the overall energy for dense networks.


title: Centrality Measures in Networks

abstract:
  We show that prominent centrality measures in network analysis are all based
on additively separable and linear treatments of statistics that capture a
node's position in the network. This enables us to provide a taxonomy of
centrality measures that distills them to varying on two dimensions: (i) which
information they make use of about nodes' positions, and (ii) how that
information is weighted as a function of distance from the node in question.
The three sorts of information about nodes' positions that are usually used --
which we refer to as "nodal statistics" -- are the paths from a given node to
other nodes, the walks from a given node to other nodes, and the geodesics
between other nodes that include a given node. Using such statistics on nodes'
positions, we also characterize the types of trees such that centrality
measures all agree, and we also discuss the properties that identify some
path-based centrality measures.


title: Excitonic superfluid phase in Double Bilayer Graphene

abstract:
  Spatially indirect excitons can be created when an electron and a hole,
confined to separate layers of a double quantum well system, bind to form a
composite Boson. Because there is no recombination pathway such excitons are
long lived making them accessible to transport studies. Moreover, the ability
to independently tune both the intralayer charge density and interlayer
electron-hole separation provides the capability to reach the low-density,
strongly interacting regime where a BEC-like phase transition into a superfluid
ground state is anticipated. To date, transport signatures of the superfluid
condensate phase have been seen only in quantum Hall bilayers composed of
double well GaAs heterostructures. Here we report observation of the exciton
condensate in the quantum Hall effect regime of double layer structures of
bilayer graphene. Correlation between the layers is identified by quantized
Hall drag appearing at matched layer densities, and the dissipationless nature
of the phase is confirmed in the counterflow geometry. Independent tuning of
the layer densities and interlayer bias reveals a selection rule involving both
the orbital and valley quantum number between the symmetry-broken states of
bilayer graphene and the condensate phase, while tuning the layer imbalance
stabilizes the condensate to temperatures in excess of 4K. Our results
establish bilayer graphene quantum wells as an ideal system in which to study
the rich phase diagram of strongly interacting Bosonic particles in the solid
state.


title: Centrally Large Subalgebras and Tracial ${\mathcal{Z}}$-Absorption

abstract:
  Let $A$ be a simple infinite dimensional stably finite unital C*-algebra, and
let $B$ be a centrally large subalgebra of $A$. We prove that if $A$ is
tracially ${\mathcal{Z}}$-absorbing if and only if $B$ is tracially
${\mathcal{Z}}$-absorbing. If $A$ and $B$ are also separable and nuclear, we
prove that $A$ is ${\mathcal{Z}}$-absorbing if and only if $B$ is
${\mathcal{Z}}$-absorbing.


title:
Model plasma membrane indicates the inner leaflet is poised to initiate
  compositional heterogeneities

abstract:
  We investigate a model of an asymmetric bilayer consisting of sphigomyelin,
phosphatidylcholine, and cholesterol in the outer leaflet, and
phosphatidyl\-ethanolamine, (PE), phosphatidylserine, and cholesterol in the
inner leaflet. Composition fluctuations are coupled to membrane fluctuations
via the bending energy which depends upon the local spontaneous curvature
dominated by the PE in the inner leaflet. This brings about a microemulsion in
that leaflet with a characteristic wavelength of 37 nm as shown by the PE-PE
structure function. Thus the inner leaflet will respond to an external
perturbation most strongly at this length. However the correlation length is
approximately 1 nm so that composition variations are not seen in the inner
leaflet itself. Depending upon the strength of the coupling between leaflets,
the outer leaflet is either a normal fluid or is also a microemulsion. In this
model then, the lipids of the plasma membrane would not evince inhomogeneities,
but would be primed to create them from the inner leaflet in response to
non-lipid perturbations.


title: Bound for preperiodic points for maps with good reduction

abstract:
  Let $K$ be a number field and let $\phi$ in $K(z)$ be a rational function of
degree $d\geq 2$. Let $S$ be the places of bad reduction for $\phi$ (including
the archimedan places). Let $Per(\phi,K)$, $PrePer(\phi, K)$, and
$Tail(\phi,K)$ be the set of $K$-rational periodic, preperiodic, and purely
preperiodic points of $\phi$, respectively. The present paper presents two main
results. The first result gives a bound for $|PrePer(\phi,K)|$ in terms of the
number of places of bad reduction $|S|$ and the degree $d$ of the rational
function $\phi$. This bound significantly improves a previous bound given by J.
Canci and L. Paladino 2014. For the second result, assuming that $|Per(\phi,K)|
\geq 4$ (resp. $|Tail(\phi,K)| \geq 3$), we prove bounds for $|Tail(\phi,K)|$
(resp. $|Per(\phi,K)|$) that depend only on the number of places of bad
reduction $|S|$ (and not on the degree $d$). We show that the hypotheses of
this result are sharp, giving counterexamples to any possible result of this
form when $|Per(\phi,K)| < 4$ (resp. $|Tail(\phi,K)| < 3$).


title: Steganalyzer performances in operational contexts

abstract:
  Steganography and steganalysis are two important branches of the information
hiding field of research. Steganography methods consist in hiding information
in such a way that the secret message is undetectable for the uninitiated.
Steganalyzis encompasses all the techniques that attempt to detect the presence
of such hidden information. This latter is usually designed by making
classifiers able to separate innocent images from steganographied ones
according to their differences on well-selected features. We wonder, in this
article whether it is possible to construct a kind of universal steganalyzer
without any knowledge regarding the steganographier side. The effects on the
classification score of a modification of either parameters or methods between
the learning and testing stages are then evaluated, while the possibility to
improve the separation score by merging many methods during learning stage is
deeper investigated.


title:
The Growth of Oligarchy in a Yard-Sale Model of Asset Exchange: A
  Logistic Equation for Wealth Condensation

abstract:
  The addition of wealth-attained advantage (WAA) to the Yard-Sale Model (YSM)
of asset exchange has been demonstrated to induce wealth condensation. In a
model of WAA for which the bias is a continuous function of the wealth
difference of the transacting agents, the condensation was shown to arise from
a second-order phase transition to a coexistence regime. In this paper, we
present the first analytic time-dependent results for this model, by showing
that the condensed wealth obeys a logistic equation in time.


title: Learning Word Embeddings from Intrinsic and Extrinsic Views

abstract:
  While word embeddings are currently predominant for natural language
processing, most of existing models learn them solely from their contexts.
However, these context-based word embeddings are limited since not all words'
meaning can be learned based on only context. Moreover, it is also difficult to
learn the representation of the rare words due to data sparsity problem. In
this work, we address these issues by learning the representations of words by
integrating their intrinsic (descriptive) and extrinsic (contextual)
information. To prove the effectiveness of our model, we evaluate it on four
tasks, including word similarity, reverse dictionaries,Wiki link prediction,
and document classification. Experiment results show that our model is powerful
in both word and document modeling.


title: Bayesian Estimation of Thermonuclear Reaction Rates

abstract:
  The problem of estimating non-resonant astrophysical S-factors and
thermonuclear reaction rates, based on measured nuclear cross sections, is of
major interest for nuclear energy generation, neutrino physics, and element
synthesis. Many different methods have been applied in the past to this
problem, almost all of them based on traditional statistics. Bayesian methods,
on the other hand, are now in widespread use in the physical sciences. In
astronomy, for example, Bayesian statistics is applied to the observation of
extra-solar planets, gravitational waves, and type Ia supernovae. However,
nuclear physics, in particular, has been slow to adopt Bayesian methods. We
present astrophysical S-factors and reaction rates based on Bayesian
statistics. We develop a framework that incorporates robust parameter
estimation, systematic effects, and non-Gaussian uncertainties in a consistent
manner. The method is applied to the d(p,$\gamma$)$^3$He,
$^3$He($^3$He,2p)$^4$He, and $^3$He($\alpha$,$\gamma$)$^7$Be reactions,
important for deuterium burning, solar neutrinos, and big bang nucleosynthesis.


title:
Optimal fitting of gaussian-apodized or under-resolved emission lines in
  Fourier Transform spectra providing new insights on the velocity structure of
  NGC 6720

abstract:
  An analysis of the kinematics of NGC 6720 is performed on the commissioning
data obtained with SITELLE, the Canada-France-Hawaii Telescope's new imaging
Fourier transform spectrometer. In order to measure carefully the small
broadening effect of a shell expansion on an unresolved emission line, we have
determined a computationally robust implementation of the convolution of a
Gaussian with a sinc instrumental line shape which avoids arithmetic overflows.
This model can be used to measure line broadening of typically a few km/s even
at low spectral resolution (R less than 5000). We have also designed the
corresponding set of Gaussian apodizing functions that are now used by ORBS,
the SITELLE's reduction pipeline. We have implemented this model in ORCS, a
fitting engine for SITELLE's data, and used it to derive the [SII] density map
of the central part of the nebula. The study of the broadening of the [NII]
lines shows that the Main Ring and the Central Lobe are two different shells
with different expansion velocities. We have also derived deep and spatially
resolved velocity maps of the Halo in [NII] and Halpha and found that the
brightest bubbles are originating from two bipolar structures with a velocity
difference of more than 35 km/s lying at the poles of a possibly unique Halo
shell expanding at a velocity of more than 15 km/s.


title:
Protein Folding in the 2D Hydrophobic-Hydrophilic (HP) Square Lattice
  Model is Chaotic

abstract:
  Among the unsolved problems in computational biology, protein folding is one
of the most interesting challenges. To study this folding, tools like neural
networks and genetic algorithms have received a lot of attention, mainly due to
the NP-completeness of the folding process. The background idea that has given
rise to the use of these algorithms is obviously that the folding process is
predictable. However, this important assumption is disputable as chaotic
properties of such a process have been recently highlighted. In this paper,
which is an extension of a former work accepted to the 2011 International Joint
Conference on Neural Networks (IJCNN11), the topological behavior of a
well-known dynamical system used for protein folding prediction is evaluated.
It is mathematically established that the folding dynamics in the 2D
hydrophobic-hydrophilic (HP) square lattice model, simply called "the 2D model"
in this document, is indeed a chaotic dynamical system as defined by Devaney.
Furthermore, the chaotic behavior of this model is qualitatively and
quantitatively deepened, by studying other mathematical properties of disorder,
namely: the indecomposability, instability, strong transitivity, and constants
of expansivity and sensitivity. Some consequences for both biological paradigms
and structure prediction using this model are then discussed. In particular, it
is shown that some neural networks seems to be unable to predict the evolution
of this model with accuracy, due to its complex behavior.


title:
Visual Processing by a Unified Schatten-$p$ Norm and $\ell_q$ Norm
  Regularized Principal Component Pursuit

abstract:
  In this paper, we propose a non-convex formulation to recover the authentic
structure from the corrupted real data. Typically, the specific structure is
assumed to be low rank, which holds for a wide range of data, such as images
and videos. Meanwhile, the corruption is assumed to be sparse. In the
literature, such a problem is known as Robust Principal Component Analysis
(RPCA), which usually recovers the low rank structure by approximating the rank
function with a nuclear norm and penalizing the error by an $\ell_1$-norm.
Although RPCA is a convex formulation and can be solved effectively, the
introduced norms are not tight approximations, which may cause the solution to
deviate from the authentic one. Therefore, we consider here a non-convex
relaxation, consisting of a Schatten-$p$ norm and an $\ell_q$-norm that promote
low rank and sparsity respectively. We derive a proximal iteratively reweighted
algorithm (PIRA) to solve the problem. Our algorithm is based on an alternating
direction method of multipliers, where in each iteration we linearize the
underlying objective function that allows us to have a closed form solution. We
demonstrate that solutions produced by the linearized approximation always
converge and have a tighter approximation than the convex counterpart.
Experimental results on benchmarks show encouraging results of our approach.


title: Topological Radicals of Nest Algebras

abstract:
  Let N be a nest on a Hilbert space H and AlgN the corresponding nest algebra.
We determine the hypocompact radical of AlgN . Other topological radicals are
also characterized.


title: On the growth of torsion in the cohomology of arithmetic groups

abstract:
  Let G be a semisimple Lie group with associated symmetric space D, and let
Gamma subset G be a cocompact arithmetic group. Let L be a lattice inside a Z
Gamma-module arising from a rational finite-dimensional complex representation
of G. Bergeron and Venkatesh recently gave a precise conjecture about the
growth of the order of the torsion subgroup H_i (Gamma_k; L )_tors as Gamma_k
ranges over a tower of congruence subgroups of Gamma. In particular they
conjectured that the ratio (log |H_i (Gamma_k ; L)_tors|)/[Gamma : Gamma_k]
should tend to a nonzero limit if and only if i= (dim(D)-1)/2 and G is a group
of deficiency 1. Furthermore, they gave a precise expression for the limit. In
this paper, we investigate computationally the cohomology of several
(non-cocompact) arithmetic groups, including GL_n (Z) for n=3,4,5 and GL_2 (O)
for various rings of integers, and observe its growth as a function of level.
In all cases where our dataset is sufficiently large, we observe excellent
agreement with the same limit as in the predictions of Bergeron--Venkatesh. Our
data also prompts us to make two new conjectures on the growth of torsion not
covered by the Bergeron--Venkatesh conjecture.


title: Using the Output Embedding to Improve Language Models

abstract:
  We study the topmost weight matrix of neural network language models. We show
that this matrix constitutes a valid word embedding. When training language
models, we recommend tying the input embedding and this output embedding. We
analyze the resulting update rules and show that the tied embedding evolves in
a more similar way to the output embedding than to the input embedding in the
untied model. We also offer a new method of regularizing the output embedding.
Our methods lead to a significant reduction in perplexity, as we are able to
show on a variety of neural network language models. Finally, we show that
weight tying can reduce the size of neural translation models to less than half
of their original size without harming their performance.


title: Hawking radiation from acoustic black holes in two space dimensions

abstract:
  We study the Hawking radiation for the acoustic black hole. In the beginning
we follow the outline of T.Jacobson but then we use a different $2+1$ vacuum
state similar to the vacuum state constructed by W.Unruh. We also use a special
form of the wave packets. The focus of the paper is to treat the 2 dimensional
case, in particular, the case when the radial and angular velocity are
variable.


title: Special and exceptional mock-Lie algebras

abstract:
  We observe several facts and make conjectures about commutative algebras
satisfying the Jacobi identity. The central question is which of those algebras
admit a faithful representation (i.e., in Lie parlance, satisfy the Ado
theorem, or, in Jordan parlance, are special).


title: On Schrodinger's bridge problem

abstract:
  In the first part of this paper we generalize the result of Georgiou-Pavon
that a positive square matrix can be scaled uniquely to a column stochastic
matrix which maps a given positive probability vector to another given positive
probability vector. In the second part of this paper we prove that a positive
quantum channel can be scaled to another positive quantum channel which maps a
given positive definite density matrix to another given positive definite
density matrix using Brower's fixed point theorem. This result proves the
Georgiou-Pavon conjecture for two positive definite density matrices in their
recent paper. We show uniqueness of fixed points for certain two positive
definite density matrices.


title: Lie algebras and around: selected questions

abstract:
  Several open questions are discussed. The topics include cohomology of
current and related Lie algebras, algebras represented as the sum of
subalgebras, structures and phenomena peculiar to characteristic $2$, and
variations on themes of Ado, Whitehead, and Banach.


title:
A Hybrid, PDE-ODE Control Strategy for Intercepting an Intelligent,
  well-informed Target in a Stationary, Cluttered Environment

abstract:
  In [1,2] a new class of intelligent controllers that can semantically embed
an agent in a spatial context constraining its behavior in a goal-oriented
manner was suggested. A controller of such a class can guide an agent in a
stationary unknown environment to a fixed target zone along an obstacle-free
trajectory. Here, an extension is suggested that would enable the interception
of an intelligent target that is maneuvering to evade capture amidst stationary
clutter (i.e. the target zone is moving). This is achieved by forcing the
differential properties of the potential field used to induce the control
action to satisfy the wave equation. Background of the problem, theoretical
developments, as well as, proofs of the ability of the modified control to
intercept the target along an obstacle-free trajectory are supplied. Simulation
results are also provided.


title: Dirac-Krein systems on star graphs

abstract:
  We study the spectrum of a self-adjoint Dirac-Krein operator with potential
on a compact star graph $\mathcal G$ with a finite number $n$ of edges. This
operator is defined by a Dirac-Krein differential expression with summable
matrix potentials on each edge, by self-adjoint boundary conditions at the
outer vertices, and by a self-adjoint matching condition at the common central
vertex of $\mathcal G$. Special attention is paid to Robin matching conditions
with parameter $\tau \in\mathbb R\cup\{\infty\}$. Choosing the decoupled
operator with Dirichlet condition at the central vertex as a reference
operator, we derive Krein's resolvent formula, introduce corresponding
Weyl-Titchmarsh functions, study the multiplicities, dependence on $\tau$, and
interlacing properties of the eigenvalues, and prove a trace formula. Moreover,
we show that, asymptotically for $R\to \infty$, the difference of the number of
eigenvalues in the intervals $[0,R)$ and $[-R,0)$ deviates from some integer
$\kappa_0$, which we call dislocation index, at most by $n+2$.


title: AllConcur: Leaderless Concurrent Atomic Broadcast (Extended Version)

abstract:
  Many distributed systems require coordination between the components
involved. With the steady growth of such systems, the probability of failures
increases, which necessitates scalable fault-tolerant agreement protocols. The
most common practical agreement protocol, for such scenarios, is leader-based
atomic broadcast. In this work, we propose AllConcur, a distributed system that
provides agreement through a leaderless concurrent atomic broadcast algorithm,
thus, not suffering from the bottleneck of a central coordinator. In AllConcur,
all components exchange messages concurrently through a logical overlay network
that employs early termination to minimize the agreement latency. Our
implementation of AllConcur supports standard sockets-based TCP as well as
high-performance InfiniBand Verbs communications. AllConcur can handle up to
135 million requests per second and achieves 17x higher throughput than today's
standard leader-based protocols, such as Libpaxos. Thus, AllConcur is highly
competitive with regard to existing solutions and, due to its decentralized
approach, enables hitherto unattainable system designs in a variety of fields.


title: Simple realizability of complete abstract topological graphs simplified

abstract:
  An abstract topological graph (briefly an AT-graph) is a pair
$A=(G,\mathcal{X})$ where $G=(V,E)$ is a graph and $\mathcal{X}\subseteq {E
\choose 2}$ is a set of pairs of its edges. The AT-graph $A$ is simply
realizable if $G$ can be drawn in the plane so that each pair of edges from
$\mathcal{X}$ crosses exactly once and no other pair crosses. We show that
simply realizable complete AT-graphs are characterized by a finite set of
forbidden AT-subgraphs, each with at most six vertices. This implies a
straightforward polynomial algorithm for testing simple realizability of
complete AT-graphs, which simplifies a previous algorithm by the author. We
also show an analogous result for independent $\mathbb{Z}_2$-realizability,
where only the parity of the number of crossings for each pair of independent
edges is specified.


title:
3-D Registration on Carotid Artery imaging data: MRI for different
  timesteps

abstract:
  A common problem which is faced by the researchers when dealing with arterial
carotid imaging data is the registration of the geometrical structures between
different imaging modalities or different timesteps. The use of the "Patient
Position" DICOM field is not adequate to achieve accurate results due to the
fact that the carotid artery is a relatively small structure and even
imperceptible changes in patient position and/or direction make it difficult.
While there is a wide range of simple/advanced registration techniques in the
literature, there is a considerable number of studies which address the
geometrical structure of the carotid artery without using any registration
technique. On the other hand the existence of various registration techniques
prohibits an objective comparison of the results using different registration
techniques. In this paper we present a method for estimating the statistical
significance that the choice of the registration technique has on the carotid
geometry. One-Way Analysis of Variance(ANOVA) showed that the p-values were
<0.0001 for the distances of the lumen from the centerline for both right and
left carotids of the patient case that was studied.


title: A Virtual Network PaaS for 3GPP 4G and Beyond Core Network Services

abstract:
  Cloud computing and Network Function Virtualization (NFV) are emerging as key
technologies to overcome the challenges facing 4G and beyond mobile systems.
Over the last few years, Platform-as-a-Service (PaaS) has gained momentum and
has become more widely adopted throughout IT enterprises. It simplifies the
applications provisioning and accelerates time-to-market while lowering costs.
Telco can leverage the same model to provision the 4G and beyond core network
services using NFV technology. However, many challenges have to be addressed,
mainly due to the specificities of network services. This paper proposes an
architecture for a Virtual Network Platform-as-a-Service (VNPaaS) to provision
3GPP 4G and beyond core network services in a distributed environment. As an
illustrative use case, the proposed architecture is employed to provision the
3GPP Home Subscriber Server (HSS) as-a-Service (HSSaaS). The HSSaaS is built
from Virtualized Network Functions (VNFs) resulting from a novel decomposition
of HSS. A prototype is implemented and early measurements are made.


title:
Propagation of singular behavior for Gaussian perturbations of random
  matrices

abstract:
  We study the asymptotic behavior of the eigenvalues of Gaussian perturbations
of large Hermitian random matrices for which the limiting eigenvalue density
vanishes at a singular interior point or vanishes faster than a square root at
a singular edge point. First, we show that the singular behavior propagates
macroscopically for sufficiently small Gaussian perturbations, and we describe
the macroscopic eigenvalue behavior for Gaussian perturbations of critical
size. Secondly, for sufficiently small Gaussian perturbations of unitary
invariant random matrices, we prove that the microscopic eigenvalue
correlations near the singular point are described by the same limiting kernel
as in the unperturbed case. We also interpret our results in terms of
nonintersecting Brownian paths with random starting positions, and we establish
multi-time generalizations of the microscopic results.


title:
Design rules for interfacial thermal conductance - building better
  bridges

abstract:
  We study the thermal conductance across solid-solid interfaces as the
composition of an intermediate matching layer is varied. In absence of
phonon-phonon interactions, an added layer can make the interfacial conductance
increase or decrease depending on the interplay between (1) an increase in
phonon transmission due to better bridging between the contacts, and (2) a
decrease in the number of available conduction channels that must conserve
their momenta transverse to the interface. When phonon-phonon interactions are
included, the added layer is seen to aid conductance when the decrease in
resistances at the contact-layer boundaries compensate for the additional layer
resistance. For the particular systems explored in this work, the maximum
conductance happens when the layer mass is close to the geometric mean of the
contact masses. The surprising result, usually associated with coherent
antireflection coatings, follows from a monotonic increase in the boundary
resistance with the interface mass ratio. This geometric mean condition readily
extends to a compositionally graded interfacial layer with an exponentially
varying mass that generates the thermal equivalent of a broadband impedance
matching network.


title:
Sparse Beltrami coefficients, integral means of conformal mappings and
  the Feynman-Kac formula

abstract:
  In this note, we give an estimate for the dimension of the image of the unit
circle under a quasiconformal mapping whose dilatation has small support. We
also prove an analogous estimate for the rate of growth of a solution of a
second-order parabolic equation given by the Feynman-Kac formula (with a
sparsely supported potential) and introduce a dictionary between the two
settings.


title: Single-world theory of the extended Wigner's world experiment

abstract:
  Frauchiger and Renner have recently claimed to prove that "Single-world
interpretations of quantum theory cannot be self-consistent". This is
contradicted by a construction due to Bell, inspired by Bohmian mechanics,
which shows that any quantum system can be modelled in such a way that there is
only one "world" at any time, but the predictions of quantum theory are
reproduced. This Bell-Bohmian theory is applied to the experiment proposed by
Frauchiger and Renner, and their argument is critically examined. It is
concluded that it is their version of "standard quantum theory", incorporating
state vector collapse upon measurement, that is not self-consistent.


title:
Efficient non-anonymous composition operator for modeling complex
  dependable systems

abstract:
  A new model composer is proposed to automatically generate non-anonymous
model replicas in the context of performability and dependability evaluation.
It is a state-sharing composer that extends the standard anonymous replication
composer in order to share the state of a replica among a set of other specific
replicas or among the eplica and another external model. This new composition
operator aims to improve expressiveness and performance with respect to the
standard anonymous replicator, namely the one adopted by the M{\"o}bius
modeling framework.


title:
Structure of the correlation function at the accumulation points of the
  logistic map

abstract:
  The correlation function of the trajectory exactly at the Feigenbaum point of
the logistic map is investigated and checked by numerical experiments. Taking
advantage of recent closed analytical results on the symbol-to-symbol
correlation function of the generating partition, we are in position to justify
the deep algorithmic structure of the correlation function apart from numerical
constants. A generalization is given for arbitrary $m\cdot 2^{\infty}$
Feigenbaum attractors.


title:
Symbol-to-symbol correlation function at the Feigenbaum point of the
  logistic map

abstract:
  Recently, simple dynamical systems such as the 1-d maps on the interval,
gained significant attention in the context of statistical physics and complex
systems. The decay of correlations in these systems, can be characterized and
measured by correlation functions. In the context of symbolic dynamics of the
non-chaotic multifractal attractors (i.e. Feigenbaum attractors), one
observable, the symbol-to-symbol correlation function, for the generating
partition of the logistic map, is rigorously introduced and checked with
numerical experiments. Thanks to the Metropolis-Stein-Stein (MSS) algorithm
this observable can be calculated analytically, giving predictions in absolute
accordance with numerical computations. The deep, algorithmic structure of the
observable is revealed clearly reflecting the complexity of the multifractal
attractor.


title:
Stability and Strength of Atomically Thin Borophene from First
  Principles Calculations

abstract:
  A new two-dimensional (2D) material, borophene (2D boron sheet), has been
grown successfully recently on single crystal Ag substrates by two parallel
experiments [Mannix \textit{et al., Science}, 2015, \textbf{350}, 1513] [Feng
\textit{et al., Nature Chemistry}, 2016, \textbf{advance online publication}].
Three main structures have been proposed ($\beta_{12}$, $\chi_3$ and striped
borophene). However, the stability of three structures is still in debate.
Using first principles calculations, we examine the dynamical, thermodynamical
and mechanical stability of $\beta_{12}$, $\chi_3$ and striped borophene.
Free-standing $\beta_{12}$ and $\chi_3$ borophene is dynamically,
thermodynamically, and mechanically stable, while striped borophene is
dynamically and thermodynamically unstable due to high stiffness along $a$
direction. The origin of high stiffness and high instability in striped
borophene along $a$ direction can both be attributed to strong directional
bonding. This work provides a benchmark for examining the relative stability of
different structures of borophene.


title: The ground truth about metadata and community detection in networks

abstract:
  Across many scientific domains, there is a common need to automatically
extract a simplified view or coarse-graining of how a complex system's
components interact. This general task is called community detection in
networks and is analogous to searching for clusters in independent vector data.
It is common to evaluate the performance of community detection algorithms by
their ability to find so-called "ground truth" communities. This works well in
synthetic networks with planted communities because such networks' links are
formed explicitly based on those known communities. However, there are no
planted communities in real world networks. Instead, it is standard practice to
treat some observed discrete-valued node attributes, or metadata, as ground
truth. Here, we show that metadata are not the same as ground truth, and that
treating them as such induces severe theoretical and practical problems. We
prove that no algorithm can uniquely solve community detection, and we prove a
general No Free Lunch theorem for community detection, which implies that there
can be no algorithm that is optimal for all possible community detection tasks.
However, community detection remains a powerful tool and node metadata still
have value so a careful exploration of their relationship with network
structure can yield insights of genuine worth. We illustrate this point by
introducing two statistical techniques that can quantify the relationship
between metadata and community structure for a broad class of models. We
demonstrate these techniques using both synthetic and real-world networks, and
for multiple types of metadata and community structure.

categories: cs.SI physics.data-an physics.soc-ph stat.ML


title: Noncrossing partitions for periodic braids

abstract:
  An element in Artin's braid group $B_n$ is called periodic if it has a power
which lies in the center of $B_n$. The conjugacy problem for periodic braids
can be reduced to the following: given a divisor $1\le d<n-1$ of $n-1$ and an
element $\alpha$ in the super summit set of $\epsilon^d$, find $\gamma\in B_n$
such that $\gamma^{-1}\alpha\gamma=\epsilon^d$, where
$\epsilon=(\sigma_{n-1}\cdots\sigma_1)\sigma_1$.
  In this article we characterize the elements in the super summit set of
$\epsilon^d$ in the dual Garside structure by studying the combinatorics of
noncrossing partitions arising from periodic braids. Our characterization
directly provides a conjugating element $\gamma$. And it determines the size of
the super summit set of $\epsilon^d$ by using the zeta polynomial of the
noncrossing partition lattice.


title: Deconstructing the Welch Equation Using $p$-adic Methods

abstract:
  The Welch map $x \rightarrow g^{x-1+c}$ is similar to the discrete
exponential map $x \rightarrow g^x$, which is used in many cryptographic
applications including the ElGamal signature scheme. This paper analyzes the
number of solutions to the Welch equation: $g^{x-1+c} \equiv x \pmod{p^e}$
where $p$ is a prime and $g$ is a unit modulo $p$, and looks at other patterns
of the equation that could possibly be exploited in a similar cryptographic
system. Since the equation is modulo $p^e$, where $p$ is a prime number,
$p$-adic methods of analysis are used in counting the number of solutions
modulo $p^e$. These methods include: $p$-adic interpolation, Hensel's lemma and
Chinese Remainder Theorem.


title: Large deviations for equilibrium measures and selection of subaction

abstract:
  Given a Lipschitz function $f:\{1,...,d\}^\mathbb{N} \to \mathbb{R}$, for
each $\beta>0$ we denote by $\mu_\beta$ the equilibrium measure of $\beta f$
and by $h_\beta$ the main eigenfunction of the Ruelle Operator $L_{\beta f}$.
Assuming that $\{\mu_{\beta}\}_{\beta>0}$ satisfy a large deviation principle,
we prove the existence of the uniform limit $V=
\lim_{\beta\to\infty}\frac{1}{\beta}\log(h_{\beta})$. Furthermore, the
expression of the deviation function is determined by its values at the points
of the union of the supports of maximizing measures. We study a class of
potentials having two ergodic maximizing measures and prove that a L.D.P. is
satisfied. The deviation function is explicitly exhibited and does not coincide
with the one that appears in the paper by Baraviera-Lopes-Thieullen which
considers the case of potentials having a unique maximizing measure.


title:
Counting Solutions to Discrete Non-Algebraic Equations Modulo Prime
  Powers

abstract:
  As society becomes more reliant on computers, cryptographic security becomes
increasingly important. Current encryption schemes include the ElGamal
signature scheme, which depends on the complexity of the discrete logarithm
problem. It is thought that the functions that such schemes use have inverses
that are computationally intractable. In relation to this, we are interested in
counting the solutions to a generalization of the discrete logarithm problem
modulo a prime power. This is achieved by interpolating to p-adic functions,
and using Hensel's lemma, or other methods in the case of singular lifting, and
the Chinese Remainder Theorem.


title: A new insight into the consistency of smoothed particle hydrodynamics

abstract:
  In this paper the problem of consistency of smoothed particle hydrodynamics
(SPH) is solved. A novel error analysis is developed in $n$-dimensional space
using the Poisson summation formula, which enables the treatment of the kernel
and particle approximation errors in combined fashion. New consistency integral
relations are derived for the particle approximation which correspond to the
cosine Fourier transform of the classically known consistency conditions for
the kernel approximation. The functional dependence of the error bounds on the
SPH interpolation parameters, namely the smoothing length $h$ and the number of
particles within the kernel support ${\cal{N}}$ is demonstrated explicitly from
which consistency conditions are seen to follow naturally. As
${\cal{N}}\to\infty$, the particle approximation converges to the kernel
approximation independently of $h$ provided that the particle mass scales with
$h$ as $m\propto h^{\beta}$, with $\beta >n$. This implies that as $h\to 0$,
the joint limit $m\to 0$, ${\cal{N}}\to\infty$, and $N\to\infty$ is necessary
for complete convergence to the continuum, where $N$ is the total number of
particles. The analysis also reveals the presence of a dominant error term of
the form $(\ln {\cal{N}})^{n}/{\cal{N}}$, which tends asymptotically to
$1/{\cal{N}}$ when ${\cal{N}}\gg 1$, as it has long been conjectured based on
the similarity between the SPH and the quasi-Monte Carlo estimates.

categories: physics.comp-ph astro-ph.CO astro-ph.GA physics.flu-dyn


title:
Universal threshold for femtosecond laser ablation with oblique
  illumination

abstract:
  We quantify the dependence of the single-shot ablation threshold on the angle
of incidence and polarization of a femtosecond laser beam, for three dissimilar
solid-state materials: a metal, a dielectric and a semiconductor. Using the
constant, linear value of the index of refraction, we calculate the laser
fluence transmitted through the air-material interface at the point of ablation
threshold. We show that, in spite of the highly nonlinear ionization dynamics
involved in the ablation process, the so defined transmitted threshold fluence
is universally independent of the angle of incidence and polarization of the
laser beam for all three material types. We suggest that angular dependence of
ablation threshold can be utilized for profiling fluence distributions in
ultra-intense femtosecond laser beams.


title: Shell Model States in the Continuum

abstract:
  We suggest a method for calculating scattering phase shifts and energies and
widths of resonances which utilizes only eigenenergies obtained in variational
calculations with oscillator basis and their dependence on oscillator basis
spacing $\hbar\Omega$. We make use of simple expressions for the $S$-matrix at
eigenstates of a finite (truncated) Hamiltonian matrix in the oscillator basis
obtained in the HORSE ($J$-matrix) formalism of quantum scattering theory. The
validity of the suggested approach is verified in calculations with model
Woods--Saxon potentials and applied to calculations of $n\alpha$ resonances and
non-resonant scattering using the no-core shell model.


title:
Smoothness of stable holonomies inside center-stable manifolds and the
  $C^2$ hypothesis in Pugh-Shub and Ledrappier-Young theory

abstract:
  Under a suitable bunching condition, we establish that stable holonomies
inside center-stable manifolds for $C^{1+\beta}$ diffeomorphisms are uniformly
bi-Lipschitz and in fact $C^{1+\text{H\"older}}$. This verifies that the
Pugh-Shub theory for ergodicity holds for suitably center-bunched,
$C^{1+\beta}$, essentially accessible, partially hyperbolic diffeomorphism and
verifies that the Ledrappier-Young entropy formulas hold for $C^{1+\beta}$
diffeomorphisms of compact manifolds.


title: On relations for zeros of $f$-polynomials and $f^{+}$-polynomials

abstract:
  Let $\Phi$ be an irreducible (possibly noncrystallographic) root system of
rank $l$ of type $P$. For the corresponding cluster complex $\Delta(P)$, which
is known as pure $(l-1)$-dimensional simplicial complex, we define the
generating function of the number of faces of $\Delta(P)$ with dimension $i-1$,
which is called the {\it $f$-polynomial}. We show that the $f$-polynomial has
exactly $l$ simple real zeros on the interval $(0, 1)$ and the smallest root
for the infinite series of type $A_l$, $B_l$ and $D_l$ monotone decreasingly
converges to zero as the rank $l$ tends to infinity. We also consider the
generating function (called the {\it $f^{+}$-polynomial}) of the number of
faces of the positive part $\Delta_{+}(P)$ of the complex $\Delta(P)$ with
dimension $i-1$, whose zeros are real and simple and are located in the
interval $(0, 1]$, including a simple root at $t=1$. We show that the roots $\{
t^{+}_{P, \nu+1} \}_{\nu=1}^{l-1}$ in decreasing order of $f^{+}$-polynomial
alternate with the roots $\{ t_{P, \nu} \}_{\nu=1}^{l}$ in decreasing order of
$f$-polynomial.


title:
Radiative Symmetry Breaking in the Supersymmetric Minimal B-L Extended
  Standard Model

abstract:
  The Standard Model (SM) of particle physics is a precise model of electroweak
interactions, however there is growing tension between the SM and observations
(neutrino oscillations, dark matter, dark energy, baryogenesis, among others).
There is no reason to expect the validity of the ad hoc SM to remain intact at
energy scales above a few TeV, thus a more fundamental theory will almost
certainly be required.
  Motivated by these considerations, we investigate a Supersymmetric version of
a natural extension of the SM, the $U(1)_{B-L}$ model, that is obtained by
gauging the accidental B-L symmetry that exists in the ordinary SM. The
Supersymmetric $U(1)_{B-L}$ extended SM can resolve the neutrino mass problem,
the dark matter problem, the hierarchy problem, and provides a mechanism for
establishing the observed baryon asymmetry of the Universe.
  When we include quantum corrections to the Higgs potential of the model, we
find that Radiative $B-L$ symmetry breaking occurs through the interplay
between large Majorana Yukawa couplings and SUSY breaking masses, and the SM
neutrino masses arise through the Type-I seesaw mechanism. We deduce from the
form RGEs that $B-L$ will be broken near the TeV scale when the Majorana Yukawa
couplings are of order 0.5, leading to TeV scale right-handed neutrinos, which
could be accessible at the LHC. We discuss the different vacua of the theory
and the viability of a right-handed neutrino dark matter candidate in the
R-parity conserving and violating sectors. A new $\mathbb{Z}_{2}$ parity is
postulated in the R-parity violating sector in which case the lightest right
handed neutrino becomes a viable Dark Matter candidate in addition to the
gravitino.


title: Online Feature Selection with Group Structure Analysis

abstract:
  Online selection of dynamic features has attracted intensive interest in
recent years. However, existing online feature selection methods evaluate
features individually and ignore the underlying structure of feature stream.
For instance, in image analysis, features are generated in groups which
represent color, texture and other visual information. Simply breaking the
group structure in feature selection may degrade performance. Motivated by this
fact, we formulate the problem as an online group feature selection. The
problem assumes that features are generated individually but there are group
structure in the feature stream. To the best of our knowledge, this is the
first time that the correlation among feature stream has been considered in the
online feature selection process. To solve this problem, we develop a novel
online group feature selection method named OGFS. Our proposed approach
consists of two stages: online intra-group selection and online inter-group
selection. In the intra-group selection, we design a criterion based on
spectral analysis to select discriminative features in each group. In the
inter-group selection, we utilize a linear regression model to select an
optimal subset. This two-stage procedure continues until there are no more
features arriving or some predefined stopping conditions are met. %Our method
has been applied Finally, we apply our method to multiple tasks including image
classification %, face verification and face verification. Extensive empirical
studies performed on real-world and benchmark data sets demonstrate that our
method outperforms other state-of-the-art online feature selection %method
methods.


title:
The MOSDEF survey: AGN multi-wavelength identification, selection biases
  and host galaxy properties

abstract:
  We present results from the MOSFIRE Deep Evolution Field (MOSDEF) survey on
the identification, selection biases, and host galaxy properties of 55 X-ray,
IR and optically-selected active galactic nuclei (AGN) at $1.4 < z < 3.8$. We
obtain rest-frame optical spectra of galaxies and AGN and use the BPT diagram
to identify optical AGN. We examine the uniqueness and overlap of the AGN
identified at different wavelengths. There is a strong bias against identifying
AGN at any wavelength in low mass galaxies, and an additional bias against
identifying IR AGN in the most massive galaxies. AGN hosts span a wide range of
star formation rate (SFR), similar to inactive galaxies once stellar mass
selection effects are accounted for. However, we find (at $\sim 2-3\sigma$
significance) that IR AGN are in less dusty galaxies with relatively higher SFR
and optical AGN in dusty galaxies with relatively lower SFR. X-ray AGN
selection does not display a bias with host galaxy SFR. These results are
consistent with those from larger studies at lower redshifts. Within
star-forming galaxies, once selection biases are accounted for, we find AGN in
galaxies with similar physical properties as inactive galaxies, with no
evidence for AGN activity in particular types of galaxies. This is consistent
with AGN being fueled stochastically in any star-forming host galaxy. We do not
detect a significant correlation between SFR and AGN luminosity for individual
AGN hosts, which may indicate the timescale difference between the growth of
galaxies and their supermassive black holes.


title: Curvature-induced stiffening of a fish fin

abstract:
  How fish modulate their fin stiffness during locomotive manoeuvres remains
unknown. We show that changing the fin's curvature modulates its stiffness.
Modelling the fin as bendable bony rays held together by a membrane, we deduce
that fin curvature is manifested as a misalignment of the principal bending
axes between neighbouring rays. An external force causes neighbouring rays to
bend and splay apart, and thus stretches the membrane. This coupling between
bending the rays and stretching the membrane underlies the increase in
stiffness. Using analysis of a 3D reconstruction of a Mackerel (Scomber
japonicus) pectoral fin, we calculate the range of stiffnesses this fin is
expected to span by changing curvature. The 3D reconstruction shows that, even
in its geometrically flat state, a functional curvature is embedded within the
fin microstructure owing to the morphology of individual rays. Since the
ability of a propulsive surface to transmit force to the surrounding fluid is
limited by its stiffness, the fin curvature controls the coupling between the
fish and its surrounding fluid. Thereby, our results provide mechanical
underpinnings and morphological predictions for the hypothesis that the spanned
range of fin stiffnesses correlates with the behaviour and the ecological niche
of the fish.


title:
A study on the growth mechanism and the process parameters controlling
  aluminum oxide thin films deposition by pulsed pressure MOCVD

abstract:
  Aluminum oxide thin films were deposited on silicon substrates under
different deposition conditions using pulse pressure metal organic chemical
vapour deposition (PP-MOCVD). The current study investigates into the growth
mechanism of the deposited film and the control of the film morphology by
varying the processing parameters of PP-MOCVD - choice of solvent,
concentration, and presence of a shield. Aluminum sec-butoxide (ASB) was used
as the aluminum source while hexane and toluene were used as the solvents. The
films were deposited at 475oC at different precursor concentrations. It was
observed that the choice of solvent has no effect on the surface morphology,
but it influenced the deposition rate. The improved deposition rate, relatively
close enthalpy of vaporisation ({\Delta}H) values and uniformity of the film,
irrespective of the growth conditions, showed that hexane was a better solvent
for ASB than toluene. A hybrid mode of vapour deposition and vapour
condensation model for thin film growth is proposed where five different
mechanisms lead to a solid film formation. These include vapour phase
deposition under low arrival rate, vapour phase deposition under high arrival
rate, Leidenfrost aerosol formation, heterogeneous particle formation and
liquid droplet impingement. The important parameter that needs to be controlled
is the precursor flux arrival rate which can be controlled by varying the
precursor concentration, use of a solvent with a low {\Delta}H and the presence
of a shield over the substrate, which influences the surface morphology and the
growth rate of the films.


title:
Reducing State Explosion for Software Model Checking with Relaxed Memory
  Consistency Models

abstract:
  Software model checking suffers from the so-called state explosion problem,
and relaxed memory consistency models even worsen this situation. What is
worse, parameterizing model checking by memory consistency models, that is, to
make the model checker as flexible as we can supply definitions of memory
consistency models as an input, intensifies state explosion. This paper
explores specific reasons for state explosion in model checking with multiple
memory consistency models, provides some optimizations intended to mitigate the
problem, and applies them to McSPIN, a model checker for memory consistency
models that we are developing. The effects of the optimizations and the
usefulness of McSPIN are demonstrated experimentally by verifying copying
protocols of concurrent copying garbage collection algorithms. To the best of
our knowledge, this is the first model checking of the concurrent copying
protocols under relaxed memory consistency models.


title: Anomaly of strings of 6d $\mathcal{N}{=}(1,0)$ theories

abstract:
  We obtain the anomaly polynomial of strings of general 6d
$\mathcal{N}{=}(1,0)$ theories in terms of anomaly inflow. Our computation
sheds some light on the reason why the simplest 6d $\mathcal{N}{=}(1,0)$ theory
has $E_8$ flavor symmetry, and also partially explains a curious numerology in
F-theory.


title:
VoxResNet: Deep Voxelwise Residual Networks for Volumetric Brain
  Segmentation

abstract:
  Recently deep residual learning with residual units for training very deep
neural networks advanced the state-of-the-art performance on 2D image
recognition tasks, e.g., object detection and segmentation. However, how to
fully leverage contextual representations for recognition tasks from volumetric
data has not been well studied, especially in the field of medical image
computing, where a majority of image modalities are in volumetric format. In
this paper we explore the deep residual learning on the task of volumetric
brain segmentation. There are at least two main contributions in our work.
First, we propose a deep voxelwise residual network, referred as VoxResNet,
which borrows the spirit of deep residual learning in 2D image recognition
tasks, and is extended into a 3D variant for handling volumetric data. Second,
an auto-context version of VoxResNet is proposed by seamlessly integrating the
low-level image appearance features, implicit shape information and high-level
context together for further improving the volumetric segmentation performance.
Extensive experiments on the challenging benchmark of brain segmentation from
magnetic resonance (MR) images corroborated the efficacy of our proposed method
in dealing with volumetric data. We believe this work unravels the potential of
3D deep learning to advance the recognition performance on volumetric image
segmentation.


title: Geodesic and curvature of piecewise flat Finsler surfaces

abstract:
  A piecewise flat Finsler metric on a triangulated surface $M$ is a metric
whose restriction to any triangle is a flat triangle in some Minkowski space
with straight edges. One of the main purposes of this work is to study the
properties of geodesics on a piecewise flat Finsler surface, especially when it
meets a vertex. Using the edge-crossing equation, we define two classes of
piecewise flat Finsler surfaces, namely, Landsberg type and Berwald type. We
deduce an explicit condition for a geodesic to be extendable at a vertex, and
define the curvature which measures the \textit{amount} of such extensions. The
dependence of the curvature on an incoming or outgoing tangent direction
corresponds to the feature of flag curvature in Finsler geometry. When the
piecewise flat Finsler surface is of Landsberg type, the curvature is only
relevant to the vertex, and we prove a combinatoric Gauss-Bonnet formula which
generalizes both the Gauss-Bonnet formulas for piecewise flat Riemannian
manifolds and for smooth Landsberg surfaces.