title: Equivalence of Emergent de Sitter Spaces from Conformal Field Theory

abstract:
  Recently, two groups have made distinct proposals for a de Sitter space that
is emergent from conformal field theory (CFT). The first proposal is that, for
two-dimensional holographic CFTs, the kinematic space of geodesics on a
spacelike slice of the asymptotically anti-de Sitter bulk is two-dimensional de
Sitter space (dS$_2$), with a metric that can be derived from the entanglement
entropy of intervals in the CFT. In the second proposal, de Sitter dynamics
emerges naturally from the first law of entanglement entropy for perturbations
around the vacuum state of CFTs. We provide support for the equivalence of
these two emergent spacetimes in the vacuum case and beyond. In particular, we
study the kinematic spaces of nontrivial solutions of $3$d gravity, including
the BTZ black string, BTZ black hole, and conical singularities. We argue that
the resulting spaces are generically globally hyperbolic spacetimes that
support dynamics given boundary conditions at future infinity. For the BTZ
black string, corresponding to a thermal state of the CFT, we show that both
prescriptions lead to an emergent hyperbolic patch of dS$_2$. We offer a
general method for relating kinematic space and the auxiliary de Sitter space
that is valid in the vacuum and thermal cases.


title: The 3D-index and normal surfaces

abstract:
  Dimofte, Gaiotto and Gukov introduced a powerful invariant, the 3D-index,
associated to a suitable ideal triangulation of a 3-manifold with torus
boundary components. The 3D-index is a collection of formal power series in
$q^{1/2}$ with integer coefficients. Our goal is to explain how the 3D-index is
a generating series of normal surfaces associated to the ideal triangulation.
This shows a connection of the 3D-index with classical normal surface theory,
and fulfills a dream of constructing topological invariants of 3-manifolds
using normal surfaces.


title:
Entanglement robustness in Heisenberg spin chains coupled to dissipative
  environment at finite temperature

abstract:
  We consider a finite one-dimensional Heisenberg XYZ spin chain under the
influence of dissipative Lindblad environment obeying the Born-Markovian
constrain in presence of an external magnetic field. We apply both closed and
open boundary conditions at zero and finite temperature. We present an exact
numerical solution for the Lindblad master equation of the system in the
Liouville space. we find that, in the free spin chain (in absence of any
environment), the entanglement at all ranges evolve in time in a non-uniform
oscillatory form that changes significantly depending on the initial state,
system size and the spatial anisotropy. The oscillatory behavior is suppressed
once the system is coupled to the environment. Furthermore, the asymptotic
behavior of the entanglement, nearest neighbor and beyond, in the system under
the influence of the environment at zero temperature is very sensitive to the
x-y spatial anisotropy, which causes them to reach either a zero or a finite
sustainable steady state value regardless of the initial state of the system.
The anisotropy in the $z-$direction may enhance the entanglement depending on
the interplay with the magnetic field applied in the same direction. As the
temperature is raised, the steady state of the short range entanglements is
found to be robust within very small non-zero temperature range, which depends
critically on the spatial anisotropy of the system. The entanglement at each
range depends differently on the spatial anisotropy. Moreover, the end to end
entanglement transfer time and speed through the open boundary chain vary
significantly based on the degree of anisotropy and the temperature of the
environment.


title:
$L_q$-estimates for stationary Stokes system with coefficients
  measurable in one direction

abstract:
  We study the stationary Stokes system with variable coefficients in the whole
space, a half space, and on bounded Lipschitz domains. In the whole and half
spaces, we obtain a priori $\dot W^1_q$-estimates for any $q\in [2,\infty)$
when the coefficients are merely measurable functions in one fixed direction.
For the system on bounded Lipschitz domains with a small Lipschitz constant, we
obtain a $W^1_q$-estimate and prove the solvability for any $q\in (1,\infty)$
when the coefficients are merely measurable functions in one direction and have
locally small mean oscillations in the orthogonal directions in each small
ball, where the direction is allowed to depend on the ball.


title: On an algorithm for receiving Sudoku matrices

abstract:
  This work examines the problem to describe an efficient algorithm for
obtaining $n^2 \times n^2$ Sudoku matrices. For this purpose, we define the
concepts of $n\times n$ $\Pi_n$-matrix and disjoint $\Pi_n$-matrices. The
article, using the set-theoretical approach, describes an algorithm for
obtaining $n^2$-tuples of $n\times n$ mutually disjoint $\Pi_n$ matrices. We
show that in input $n^2$ mutually disjoint $\Pi_n$ matrices, it is not
difficult to receive a Sudoku matrix.


title:
Observations, Thermochemical Calculations, and Modeling of Exoplanetary
  Atmospheres

abstract:
  This dissertation as a whole aims to provide means to better understand
hot-Jupiter planets through observing, performing thermochemical calculations,
and modeling their atmospheres. We used Spitzer multi-wavelength
secondary-eclipse observations and targets with high signal-to-noise ratios, as
their deep eclipses allow us to detect signatures of spectral features and
assess planetary atmospheric structure and composition with greater certainty.
Chapter 1 gives a short introduction. Chapter 2 presents the Spitzer
secondary-eclipse analysis and atmospheric characterization of WASP-14b.
WASP-14b is a highly irradiated, transiting hot Jupiter. By applying a Bayesian
approach in the atmospheric analysis, we found an absence of thermal inversion
contrary to theoretical predictions. Chapter 3 describes the infrared
observations of WASP-43b Spitzer secondary eclipses, data analysis, and
atmospheric characterization. WASP-43b is one of the closest-orbiting hot
Jupiters, orbiting one of the coolest stars with a hot Jupiter. The atmospheric
analysis ruled out a strong thermal inversion in its dayside atmosphere.
Chapter 4 presents an open-source Thermochemical Equilibrium Abundances (TEA)
code and its application to several hot Jupiters. TEA calculates the abundances
of gaseous species using the Gibbs free-energy minimization method within an
iterative Lagrangian optimization scheme. The code is written in Python and
available to the community via http://github.com/dzesmin/TEA. Chapter 5
presents my contributions to an open-source Bayesian Atmospheric Radiative
Transfer (BART) code, and its application to WASP-43b. BART characterizes
planetary atmospheres based on the observed spectroscopic information. It
initializes a planetary atmospheric model, performs radiative-transfer
calculations to produce models of planetary spectra, and using a statistical
module compares models with observations.


title: A parametrised family of Mordell curves

abstract:
  An elliptic curve defined by an equation of the type $y^2=x^3+d$ is called a
Mordell curve. We obtain a parametrised family of Mordell curves whose rank, in
general, is at least three, and whose torsion group is
$\mathbb{Z}/3\mathbb{Z}$.


title:
Predicting Social Status via Social Networks: A Case Study on
  University, Occupation, and Region

abstract:
  Social status refers to the relative position within the society. It is an
important notion in sociology and related research. The problem of measuring
social status has been studied for many years. Various indicators are proposed
to assess social status of individuals, including educational attainment,
occupation, and income/wealth. However, these indicators are sometimes
difficult to collect or measure.
  We investigate social networks for alternative measures of social status.
Online activities expose certain traits of users in the real world. We are
interested in how these activities are related to social status, and how social
status can be predicted with social network data. To the best of our knowledge,
this is the first study on connecting online activities with social status in
reality.
  In particular, we focus on the network structure of microblogs in this study.
A user following another implies some kind of status. We cast the predicted
social status of users to the "status" of real-world entities, e.g.,
universities, occupations, and regions, so that we can compare and validate
predicted results with facts in the real world. We propose an efficient
algorithm for this task and evaluate it on a dataset consisting of 3.4 million
users from Sina Weibo. The result shows that it is possible to predict social
status with reasonable accuracy using social network data. We also point out
challenges and limitations of this approach, e.g., inconsistence between online
popularity and real-world status for certain users. Our findings provide
insights on analyzing online social status and future designs of ranking
schemes for social networks.


title:
Multiplicities of charged pions and unidentified charged hadrons from
  deep-inelastic scattering of muons off an isoscalar target

abstract:
  Multiplicities of charged pions and unidentified hadrons produced in
deep-inelastic scattering were measured in bins of the Bjorken scaling variable
$x$, the relative virtual-photon energy $y$ and the relative hadron energy $z$.
Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam and
an isoscalar target ($^6$LiD). They cover the kinematic domain in the photon
virtuality $Q^2$ > 1(GeV/c$)^2$, $0.004 < x < 0.4$, $0.2 < z < 0.85$ and $0.1 <
y < 0.7$. In addition, a leading-order pQCD analysis was performed using the
pion multiplicity results to extract quark fragmentation functions.


title: A note on the nonexistence of quasi-harmonic spheres

abstract:
  In this paper we study the properties of quasi-harmonic spheres from $\R^m,
m>2$. We show that if the universal covering $\tilde N$ of $N$ admits a
nonnegative strictly convex function $\rho$ with the exponential growth
condition $\rho(y)\leq C\exp\left(\frac14\tilde d(y)^{2/m}\right)$ where
$\tilde d(y)$ is the distance function on $\tilde N$, then $N$ does not admit a
quasi-harmonic sphere, which generalize Li-Zhu's result \cite{Li2010non}. We
also show that if $u$ is a quasi-harmonic sphere, then the property that $u$ is
of finite energy ($\int_{\R^m}e(u)e^{-\abs{x}^2/4}\dif x<\infty$) is equivalent
to the property that $u$ satisfies the large energy condition
($\lim_{R\to\infty}R^{m}e^{-R^2/4}\int_{B_R(0)}e(u)e^{-\abs{x}^2/4}\diff x=0$).


title:
Graphene kirigami as a platform for stretchable and tunable quantum dot
  arrays

abstract:
  The quantum transport properties of a graphene kirigami similar to those
studied in recent experiments are calculated in the regime of elastic,
reversible deformations. Our results show that, at low electronic densities,
the conductance profile of such structures replicates that of a system of
coupled quantum dots, characterized by a sequence of minibands and stop-gaps.
The conductance and I-V curves have different characteristics in the distinct
stages of elastic deformation that characterize the elongation of these
structures. Notably, the effective coupling between localized states is
strongly reduced in the small elongation stage, whereas in the large elongation
regime the development of strong, localized pseudomagnetic field barriers can
reinforce the coupling and reestablish resonant tunneling across the kirigami.
This provides an interesting example of interplay between geometry and
pseudomagnetic field-induced confinement. The alternating miniband and
stop-gaps in the transmission lead to I-V characteristics with negative
differential conductance in well defined energy/doping ranges. These effects
should be stable in a realistic scenario that includes edge roughness and
Coulomb interactions, as these are expected to further promote localization of
states at low energies in narrow segments of graphene nanostructures.


title: The axiom system of classical harmony

abstract:
  This paper provides a new mathematical axiom system for classical harmony,
which is a prescriptive rule system for composing music, introduced in the
second half of the 18th century. The clearest model of classical harmony is
given by the homophonic four-part pieces of music. The form of these pieces is
based on the earlier four-part chorale adaptations of J. S. Bach. Our paper
logically structures the musical phenomena belonging to the research area of
classical harmony. Its main result, the fundamental theorem of tonality,
provides a way to construct a complete axiom system which incorporates the
well-known classical compositional principles about chord changing and voice
leading. In this axiom system, a piece complies with classical harmony if it
satisfies the formal requirements of four-part homophony and it does not
violate any classical chord-changing or modulational rules.


title: Low-density locality-sensitive hashing boosts metagenomic binning

abstract:
  Metagenomic binning is an essential task in analyzing metagenomic sequence
datasets. To analyze structure or function of microbial communities from
environmental samples, metagenomic sequence fragments are assigned to their
taxonomic origins. Although sequence alignment algorithms can readily be used
and usually provide high-resolution alignments and accurate binning results,
the computational cost of such alignment-based methods becomes prohibitive as
metagenomic datasets continue to grow. Alternative compositional-based methods,
which exploit sequence composition by profiling local short k-mers in
fragments, are often faster but less accurate than alignment-based methods.
Inspired by the success of linear error correcting codes in noisy channel
communication, we introduce Opal, a fast and accurate novel compositional-based
binning method. It incorporates ideas from Gallager's low-density parity-check
code to design a family of compact and discriminative locality-sensitive
hashing functions that encode long-range compositional dependencies in long
fragments. By incorporating the Gallager LSH functions as features in a simple
linear SVM, Opal provides fast, accurate and robust binning for datasets
consisting of a large number of species, even with mutations and sequencing
errors. Opal not only performs up to two orders of magnitude faster than BWA,
an alignment-based binning method, but also achieves improved binning accuracy
and robustness to sequencing errors. Opal also outperforms models built on
traditional k-mer profiles in terms of robustness and accuracy. Finally, we
demonstrate that we can effectively use Opal in the "coarse search" stage of a
compressive genomics pipeline to identify a much smaller candidate set of
taxonomic origins for a subsequent alignment-based method to analyze, thus
providing metagenomic binning with high scalability, high accuracy and high
resolution.


title: GPIC - GPU Power Iteration Cluster

abstract:
  This work presents a new clustering algorithm, the GPIC, a Graphics
Processing Unit (GPU) accelerated algorithm for Power Iteration Clustering
(PIC). Our algorithm is based on the original PIC proposal, adapted to take
advantage of the GPU architecture, maintining the algorith original properties.
The proposed method was compared against the serial and parallel Spark
implementation, achieving a considerable speed-up in the test problems.


title: The upgrade system of BESIII ETOF with MRPC technology

abstract:
  The Beijing Spectrometer III (BESIII) endcap Time-Of-Filght (ETOF) was
proposed to upgrade with Multigap Resistive Plate Chamber (MRPC) technology to
substitute the current ETOF of scintillator+PMT for extending time resolutin
better than 80 ps and enhance the particle identification capability to satisfy
the higher precision requirement of physics. The ETOF system including MRPC
modules, front end electronics (FEE), CLOCK module, fast control boards and
time to digital modules (TDIG), has been designed, constructed and done some
experimental tests seperately. Aiming at examining the quality of entire ETOF
system and training the operation of all participated parts, a cosmic ray test
system was built at the laboratory and underwent about three months to
guarantee performance. In this paper the results will be presented indicating
that the entire ETOF system works well and satisfies the requirements of the
upgrade.


title: Identifying the Spectral Representation of Hilbertian Time Series

abstract:
  We provide square-root n consistency results regarding estimation of the
spectral representation of covariance operators of Hilbertian time series, in a
setting with imperfect measurements. This is a generalization of the method
developed in Bathia et al. (2010). The generalization relies on an important
property of centered random elements in a separable Hilbert space, namely, that
they lie almost surely in the closed linear span of the associated covariance
operator. We provide a straightforward proof to this fact. This result is, to
our knowledge, overlooked in the literature. It incidentally gives a rigorous
formulation of PCA in Hilbert spaces.


title: Synthesizing Training Images for Boosting Human 3D Pose Estimation

abstract:
  Human 3D pose estimation from a single image is a challenging task with
numerous applications. Convolutional Neural Networks (CNNs) have recently
achieved superior performance on the task of 2D pose estimation from a single
image, by training on images with 2D annotations collected by crowd sourcing.
This suggests that similar success could be achieved for direct estimation of
3D poses. However, 3D poses are much harder to annotate, and the lack of
suitable annotated training images hinders attempts towards end-to-end
solutions. To address this issue, we opt to automatically synthesize training
images with ground truth pose annotations. Our work is a systematic study along
this road. We find that pose space coverage and texture diversity are the key
ingredients for the effectiveness of synthetic training data. We present a
fully automatic, scalable approach that samples the human pose space for
guiding the synthesis procedure and extracts clothing textures from real
images. Furthermore, we explore domain adaptation for bridging the gap between
our synthetic training images and real testing photos. We demonstrate that CNNs
trained with our synthetic images out-perform those trained with real photos on
3D pose estimation tasks.


title: Modeling and Simulation of Passenger Traffic in a National Airport

abstract:
  Optimal operation of a country's air transport infrastructure plays a major
role in the economic development of nations. Due to the increasing use of air
transportation in today's world, flights' boarding times have become a concern
for both airlines and airports, thus the importance of knowing beforehand how
changes in flights demand parameters and physical airport layout will affect
passengers flow and boarding times. This paper presents a pedestrian modeling
study in which a national airport passenger flow was analyzed. The study was
conducted at Vanguardia National Airport in Villavicencio, Meta, Colombia.
Different effects of structural changes are shown and provide judging elements
for decision makers regarding passenger traffic in airport design.


title: Users Polarization on Facebook and Youtube

abstract:
  On social media algorithms for content promotion, accounting for users
preferences, might limit the exposure to unsolicited contents. In this work, we
study how the same contents (videos) are consumed on different platforms --
i.e. Facebook and YouTube -- over a sample of $12M$ of users. Our findings show
that the same content lead to the formation of echo chambers, irrespective of
the online social network and thus of the algorithm for content promotion.
Finally, we show that the users' commenting patterns are accurate early
predictors for the formation of echo-chambers.


title: Secure M-PSK Communication via Directional Modulation

abstract:
  In this work, a directional modulation-based technique is devised to enhance
the security of a multi-antenna wireless communication system employing M-PSK
modulation to convey information. The directional modulation method operates by
steering the array beam in such a way that the phase of the received signal at
the receiver matches that of the intended M-PSK symbol. Due to the difference
between the channels of the legitimate receiver and the eavesdropper, the
signals received by the eavesdropper generally encompass a phase component
different than the actual symbols. As a result, the transceiver which employs
directional modulation can impose a high symbol error rate on the eavesdropper
without requiring to know the eavesdropper's channel. The optimal directional
modulation beamformer is designed to minimize the consumed power subject to
satisfying a specific resulting phase and minimal signal amplitude at each
antenna of the legitimate receiver. The simulation results show that the
directional modulation results in a much higher symbol error rate at the
eavesdropper compared to the conventional benchmark scheme, i.e., zero-forcing
precoding at the transmitter.


title:
A Euclidean Lattice Formulation of D=5 Maximally Supersymmetric
  Yang-Mills Theory

abstract:
  We construct lattice action for five-dimensional maximally supersymmetric
Yang-Mills theory. This supersymmetric lattice formulation can be used to
explore the non-perturbative regime of the continuum target theory, which has a
known gravitational dual.


title:
Vesicle adhesion reveals novel universal relationships for biophysical
  characterization

abstract:
  Adhesion plays an integral role in diverse biological functions ranging from
cellular transport to tissue development. Estimation of adhesion strength,
therefore, becomes important to gain biophysical insight into these phenomena.
In this Letter, we use curvature elasticity to present non-intuitive, yet
remarkably simple, universal relationships that capture vesicle-substrate
interactions. Our study reveals that the inverse of the height, exponential of
the contact area, and the force required to detach the vesicle from the
substrate vary linearly with the square root of the adhesion energy. These
relationships not only provide efficient strategies to tease out adhesion
energy of biological molecules but can also be used to characterize the
physical properties of elastic biomimetic nanoparticles. We validate the
modeling predictions with experimental data from two previous studies.


title:
Comparing descent obstruction and Brauer-Manin obstruction for open
  varieties

abstract:
  We provide a relation between Brauer-Manin obstruction and descent
obstruction for torsors over open varieties under a connected linear algebraic
group or a group of multiplicative type is given. Such a relation is further
refined for torsors under a torus. As an appliaction, we prove that the
semi-simple part of a connected linear algebraic group will satisfy strong
approximation with Brauer-Manin obstruction if G iteself satisfies strong
approximation with Brauer-Manin obstruction.The equivalence between descent
obstruction and etale Brauer-Manin obstruction for smooth projective varieties
is extended to smooth quasi-projective varieties, which provides the
perspective to study integral points.


title: On sign embeddings and narrow operators on $L_2$

abstract:
  The goal of this note is two-fold. First we present a brief overview of
"weak" embeddings, with a special emphasis on sign embeddings which were
introduced by H. P. Rosenthal in the early 1980s. We also discuss the related
notion of narrow operators, which was introduced by A. Plichko and M. Popov in
1990. We give examples of applications of these notions in the geometry of
Banach spaces and in other areas of analysis. We also present some open
problems.
  In the second part we prove that Rosenthal's celebrated characterization of
narrow operators on $L_1$ is also true for operators on $L_2$. This answers,
for $p=2$, a question posed by Plichko and Popov in 1990. For $1<p<2$ the
problem remains open.


title: An Experimental Study of Dynamic Dominators

abstract:
  Motivated by recent applications of dominator computations, we consider the
problem of dynamically maintaining the dominators of flow graphs through a
sequence of insertions and deletions of edges. Our main theoretical
contribution is a simple incremental algorithm that maintains the dominator
tree of a flow graph with $n$ vertices through a sequence of $k$ edge
insertions in $O(m\min\{n,k\}+kn)$ time, where $m$ is the total number of edges
after all insertions. Moreover, we can test in constant time if a vertex $u$
dominates a vertex $v$, for any pair of query vertices $u$ and $v$. Next, we
present a new decremental algorithm to update a dominator tree through a
sequence of edge deletions. Although our new decremental algorithm is not
asymptotically faster than repeated applications of a static algorithm, i.e.,
it runs in $O(mk)$ time for $k$ edge deletions, it performs well in practice.
By combining our new incremental and decremental algorithms we obtain a fully
dynamic algorithm that maintains the dominator tree through intermixed sequence
of insertions and deletions of edges. Finally, we present efficient
implementations of our new algorithms as well as of existing algorithms, and
conduct an extensive experimental study on real-world graphs taken from a
variety of application areas.


title: On the number of mutually disjoint pairs of S-permutation matrices

abstract:
  This work examines the concept of S-permutation matrices, namely $n^2 \times
n^2$ permutation matrices containing a single 1 in each canonical $n \times n$
subsquare (block). The article suggests a formula for counting mutually
disjoint pairs of $n^2 \times n^2$ S-permutation matrices in the general case
by restricting this task to the problem of finding some numerical
characteristics of the elements of specially defined for this purpose
factor-set of the set of $n \times n$ binary matrices. The paper describe an
algorithm that solves the main problem. To do that, every $n\times n$ binary
matrix is represented uniquely as a n-tuple of integers.


title:
Thermal photon production from gluon fusion induced by magnetic fields
  in relativistic heavy-ion collisions

abstract:
  We compute the production of thermal photons in relativistic heavy-ion
collisions by gluon fusion in the presence of an intense magnetic field, and
during the early stages of the reaction. This photon yield is an excess over
calculations that do not consider magnetic field effects. We add this excess to
recent hydrodynamic calculations that are close to describing the experimental
transverse momentum distribution in RHIC and LHC. We then show that with
reasonable values for the temperature, magnetic field strength, and strong
coupling constant, our results provide a very good description of such excess.
These results support the idea that the origin of at least some of the photon
excess observed in heavy-ion experiments may arise from magnetic field induced
processes.


title: Canonical binary matrices related to bipartite graphs

abstract:
  The current paper is dedicated to the problem of finding the number of
mutually non isomorphic bipartite graphs of the type $g=\langle R_g ,C_g ,E_g
\rangle$ at given $n=|R_g |$ and $m=|C_g |$, where $R_g$ and $C_g$ are the two
disjoint parts of the vertices of the graphs $g$, and $E_g$ is the set of
edges, $Eg \subseteq R_g \times C_g$. For this purpose, the concept of
canonical binary matrix is introduced. The different canonical matrices
unambiguously describe the different with exactness up to isomorphism bipartite
graphs. We have found a necessary and sufficient condition an arbitrary matrix
to be canonical. This condition could be the base for realizing recursive
algorithm for finding all $n \times m$ canonical binary matrices and
consequently for finding all with exactness up to isomorphism binary matrices
with cardinality of each part equal to $n$ and $m$.


title: Soccer Field Localization from a Single Image

abstract:
  In this work, we propose a novel way of efficiently localizing a soccer field
from a single broadcast image of the game. Related work in this area relies on
manually annotating a few key frames and extending the localization to similar
images, or installing fixed specialized cameras in the stadium from which the
layout of the field can be obtained. In contrast, we formulate this problem as
a branch and bound inference in a Markov random field where an energy function
is defined in terms of field cues such as grass, lines and circles. Moreover,
our approach is fully automatic and depends only on single images from the
broadcast video of the game. We demonstrate the effectiveness of our method by
applying it to various games and obtain promising results. Finally, we posit
that our approach can be applied easily to other sports such as hockey and
basketball.


title:
Construction of a Pragmatic Base Line for Journal Classifications and
  Maps Based on Aggregated Journal-Journal Citation Relations

abstract:
  A number of journal classification systems have been developed in
bibliometrics since the launch of the Citation Indices by the Institute of
Scientific Information (ISI) in the 1960s. These systems are used to normalize
citation counts with respect to field-specific citation patterns. The best
known system is the so-called "Web-of-Science Subject Categories" (WCs). In
other systems papers are classified by algorithmic solutions. Using the Journal
Citation Reports 2014 of the Science Citation Index and the Social Science
Citation Index (n of journals = 11,149), we examine options for developing a
new system based on journal classifications into subject categories using
aggregated journal-journal citation data. Combining routines in VOSviewer and
Pajek, a tree-like classification is developed. At each level one can generate
a map of science for all the journals subsumed under a category. Nine major
fields are distinguished at the top level. Further decomposition of the social
sciences is pursued for the sake of example with a focus on journals in
information science (LIS) and science studies (STS). The new classification
system improves on alternative options by avoiding the problem of randomness in
each run that has made algorithmic solutions hitherto irreproducible.
Limitations of the new system are discussed (e.g. the classification of
multi-disciplinary journals). The system's usefulness for field-normalization
in bibliometrics should be explored in future studies.


title:
Liouville principles and a large-scale regularity theory for random
  elliptic operators on the half-space

abstract:
  We consider the large-scale regularity of solutions to second-order linear
elliptic equations with random coefficient fields. In contrast to previous
works on regularity theory for random elliptic operators, our interest is in
the regularity at the boundary: We consider problems posed on the half-space
with homogeneous Dirichlet boundary conditions and derive an associated
$C^{1,\alpha}$-type large-scale regularity theory in the form of a
corresponding decay estimate for the homogenization-adapted tilt-excess. This
regularity theory entails an associated Liouville-type theorem. The results are
based on the existence of homogenization correctors adapted to the half-space
setting, which we construct - by an entirely deterministic argument - as a
modification of the homogenization corrector on the whole space. This adaption
procedure is carried out inductively on larger scales, crucially relying on the
regularity theory already established on smaller scales.


title: Point defects stabilise cubic Mo-N and Ta-N

abstract:
  We employ \textit{ab initio} calculations to investigate energetics of point
defects in metastable rocksalt cubic Ta-N and Mo-N. Our results reveal a strong
tendency to off-stoichiometry, i.e. defected structures are predicted to be
more stable than perfect ones with 1:1 metal-to-nitrogen stoichiometry, in
agreement with previous literature reports. While Ta-N significantly favours
metal vacancies, Mo-N exhibits similar energies of formation regardless of the
vacancy type ($V_\text{Mo}$, $V_\text{N}$) as long as their concentration is
below $\approx15\,\text{at.\%}$. The overall lowest energy of formation were
obtained for $\text{Ta}_{0.78}\text{N}$ and $\text{Mo}_{0.91}\text{N}$, which
are hence predicted to be the most stable compositions. To account for various
experimental condition during synthesis, we further evaluated the phase
stability as a function of chemical potential of individual species. The
proposed phase diagrams reveal four stable compositions,
$\text{Mo}_{0.84}\text{N}$, $\text{Mo}_{0.91}\text{N}$, $\text{MoN}_{0.69}$ and
$\text{MoN}_{0.44}$, in the case of Mo-N and nine stable compositions in the
case of Ta-N indicating the crucial role of metal under-stoichiometry, since
$\text{Ta}_{0.75}\text{N}$ and $\text{Ta}_{0.78}\text{N}$ significantly
dominate the diagram. These results are important for understanding and
designing experiments using non-equilibrium deposition techniques. Finally, we
discuss a role of defects ordering and estimate a cubic lattice parameter as a
function of a defect contents.


title: Nonlinear ring waves in a two-layer fluid

abstract:
  Surface and interfacial weakly-nonlinear ring waves in a two-layer fluid are
modelled numerically, within the framework of the recently derived
2+1-dimensional cKdV-type equation. In a case study, we consider concentric
waves from a localised initial condition and waves in a 2D version of the
dam-break problem, as well as discussing the effect of a piecewise-constant
shear flow. The modelling shows, in particular, the formation of 2D dispersive
shock waves (DSWs) and oscillatory wave trains. The surface and interfacial
DSWs generated in our numerical experiments look distinctively different.


title:
Field-Driven Self-Assembly of Magnetite Nanoparticles Investigated Using
  Small-Angle Neutron Scattering

abstract:
  The magnetic-field-induced assembly of magnetic nanoparticles (NPs) provides
a unique and flexible strategy in the design and the fabrication of functional
nanostructures and devices. We have investigated the field-driven self-assembly
of core-shell magnetite NPs dispersed in toluene by means of in situ small
angle neutron scattering (SANS). The form factor of the core-shell NPs was
characterized and analyzed using SANS with polarized neutrons. Large-scale
aggregation of magnetite NPs has formed above 0.02 T as indicated by very-small
angle neutron scattering measurements. Three-dimensional long-range ordered
superlattice of magnetite NPs was revealed under the application of moderate
magnetic field. The crystal structure of the superlattice has been identified
as a face-centered cubic one.


title:
Terahertz-induced resistance oscillations in high mobility
  two-dimensional electron systems

abstract:
  We report on a theoretical work on magnetotransport under terahertz radiation
with high mobility two-dimensional electron systems. We focus on the
interaction between the obtained radiation-induced magnetoresistance
oscillations (RIRO) and the Shubnikov-de Haas (SdHO) oscillations. We study two
effects experimentally obtained with this radiation. First, the observed
disappearance of the SdHO oscillations simultaneously with the vanishing
resistance at the zero resistance states region. And secondly the strong
modulation of the SdHO oscillations at sufficient terahertz radiation power. We
conclude that both effects share the same physical origin, the interference
between the average advanced distance by the scattered electron between
irradiated Landau states, (RIRO), and the available initial density of states
at a certain magnetic field, (SdHO). Thus, from a physical standpoint, what the
terahertz experiments and theoretical simulations reveal is, on the one hand,
the oscillating nature of the Landau states subjected to radiation and, on the
other hand, how they behave in the presence of scattering.


title:
Computation of Eigenvalues, Spectral Zeta Functions and
  Zeta-Determinants on Hyperbolic Surfaces

abstract:
  These are lecture notes from a series of three lectures given at the summer
school "Geometric and Computational Spectral Theory" in Montreal in June 2015.
The aim of the lecture was to explain the mathematical theory behind
computations of eigenvalues and spectral determinants in geometrically
non-trivial contexts.


title: CaSCADE: Compressed Carrier and DOA Estimation

abstract:
  Spectrum sensing and direction of arrival (DOA) estimation have been
thoroughly investigated, both separately and as a joint task. Estimating the
support of a set of signals and their DOAs is crucial to many signal processing
applications, such as Cognitive Radio (CR). A challenging scenario, faced by
CRs, is that of multiband signals, composed of several narrowband transmissions
spread over a wide spectrum each with unknown carrier frequencies and DOAs. The
Nyquist rate of such signals is high and constitutes a bottleneck both in the
analog and digital domains. To alleviate the sampling rate issue, several
sub-Nyquist sampling methods, such as multicoset sampling or the modulated
wideband converter (MWC), have been proposed in the context of spectrum
sensing. In this work, we first suggest an alternative sub-Nyquist sampling and
signal reconstruction method to the MWC, based on a uniform linear array (ULA).
We then extend our approach to joint spectrum sensing and DOA estimation and
propose the CompreSsed CArrier and DOA Estimation (CaSCADE) system, composed of
an L-shaped array with two ULAs. In both cases, we derive perfect recovery
conditions of the signal parameters (carrier frequencies and DOAs if relevant)
and the signal itself and provide two reconstruction algorithms, one based on
the ESPRIT method and the second on compressed sensing techniques. Both our
joint carriers and DOAs recovery algorithms overcome the well-known pairing
issue between the two parameters. Simulations demonstrate that our alternative
spectrum sensing system outperforms the MWC in terms of recovery error and
design complexity and show joint carrier frequencies and DOAs from our CaSCADE
system's sub-Nyquist samples.


title:
A plug-in bandwidth selection procedure for long run covariance
  estimation with stationary functional time series

abstract:
  In arenas of application including environmental science, economics, and
medicine, it is increasingly common to consider time series of curves or
functions. Many inferential procedures employed in the analysis of such data
involve the long run covariance function or operator, which is analogous to the
long run covariance matrix familiar to finite dimensional time series analysis
and econometrics. This function may be naturally estimated using a smoothed
periodogram type estimator evaluated at frequency zero that relies crucially on
the choice of a bandwidth parameter. Motivated by a number of prior
contributions in the finite dimensional setting, we propose a bandwidth
selection method that aims to minimize the estimator's asymptotic mean squared
normed error (AMSNE) in $L^2[0,1]^2$. As the AMSNE depends on unknown
population quantities including the long run covariance function itself,
estimates for these are plugged in in an initial step after which the estimated
AMSNE can be minimized to produce an empirical optimal bandwidth. We show that
the bandwidth produced in this way is asymptotically consistent with the AMSNE
optimal bandwidth, with quantifiable rates, under mild stationarity and moment
conditions. These results and the efficacy of the proposed methodology are
evaluated by means of a comprehensive simulation study, from which we can offer
practical advice on how to select the bandwidth parameter in this setting.


title: Complexity volumes of splittable groups

abstract:
  Using graph of groups decompositions of finitely generated groups, we define
Euler characteristic type invariants which are non-zero in many interesting
classes of finitely presented, hyperbolic, limit and CSA groups, including
elementarily free groups and one-ended torsion-free hyperbolic groups whose JSJ
decomposition contains a maximal hanging Fuchsian vertex group.


title:
Weak dispersive estimates for fractional Aharonov-Bohm-Schr\"odinger
  groups

abstract:
  We prove local smoothing, local energy decay and weighted Strichartz
inequalities for fractional Schr\"odinger equations with a Aharonov-Bohm
magnetic field in 2D. Explicit representations of the flows in terms of
spherical expansions of the Hamiltonians are involved in the study. An
improvement of the free estimate is proved, when the total flux of the magnetic
field through the unit sphere is not an integer.


title:
IPA in the Loop: Control Design for Throughput Regulation in Computer
  Processors

abstract:
  A new technique for performance regulation in event-driven systems, recently
proposed by the authors, consists of an adaptive-gain integral control. The
gain is adjusted in the control loop by a real-time estimation of the
derivative of the plant-function with respect to the control input. This
estimation is carried out by Infinitesimal Perturbation Analysis (IPA). The
main motivation comes from applications to throughput regulation in computer
processors, where to-date, testing and assessment of the proposed control
technique has been assessed by simulation. The purpose of this paper is to
report on its implementation on a machine, namely an Intel Haswell
microprocessor, and compare its performance to that obtained from cycle-level,
full system simulation environment. The intrinsic contribution of the paper to
the Workshop on Discrete Event System is in describing the process of taking an
IPA-based design and simulation to a concrete implementation, thereby providing
a bridge between theory and applications.


title: The space of arcs of an algebraic variety

abstract:
  The paper surveys several results on the topology of the space of arcs of an
algebraic variety and the Nash problem on the arc structure of singularities.


title:
Thermal Global Expansion Coefficient Measurement for a Harmonic Trapped
  Gas Across Bose-Einstein Condensation

abstract:
  We report the measurement of the global thermal expansion coefficient of a
confined Bose gas of $^{87}\rm Rb$ in a harmonic potential around the
Bose-Einstein condensation transition temperature. We use the concept of global
thermodynamic variables, previously introduced and appropriated for a
non-homogeneous system. We observe the behavior of the thermal expansion
coefficient above and below the critical temperature showing the lambda-like
shape present in superfluid helium. The study demonstrates the potentiality of
global thermodynamic variables for the investigation of properties across the
critical temperature and a new way to study the thermodynamic properties of the
quantum systems.


title: Construction methods for generalized bent functions

abstract:
  Generalized bent (gbent) functions is a class of functions $f: \mathbb{Z}_2^n
\rightarrow \mathbb{Z}_q$, where $q \geq 2$ is a positive integer, that
generalizes a concept of classical bent functions through their co-domain
extension. A lot of research has recently been devoted towards derivation of
the necessary and sufficient conditions when $f$ is represented as a collection
of Boolean functions. Nevertheless, apart from the necessary conditions that
these component functions are bent when $n$ is even (respectively semi-bent
when $n$ is odd), no general construction method has been proposed yet for $n$
odd case. In this article, based on the use of the well-known
Maiorana-McFarland (MM) class of functions, we give an explicit construction
method of gbent functions, for any even $q >2$ when $n$ is even and for any $q$
of the form $q=2^r$ (for $r>1$) when $n$ is odd. Thus, a long-term open problem
of providing a general construction method of gbent functions, for odd $n$, has
been solved. The method for odd $n$ employs a large class of disjoint spectra
semi-bent functions with certain additional properties which may be useful in
other cryptographic applications.


title: O$_2$ adsorption trends on small supported PtNi clusters

abstract:
  We present a systematic analysis of molecular oxygen (O$_2$) adsorption
trends on bimetallic PtNi clusters and their monometallic counterparts
supported on MgO(100), by means of periodic DFT calculations for sizes between
25 up to 58 atoms. O$_2$ adsorption was studied on a variety of inequivalent
sites for different structural motifs, such as truncated octahedral (TO),
cuboctahedral (CO), icosahedral (Ih) and decahedral (Dh) geometries. We found
that O$_2$ prefers to bind on top of two metal atoms, parallel to the cluster,
with an average chemisorption energy of 1.09 eV (PtNi), 1.07 eV (Pt) and 2.09
eV (Ni), respectively. The largest adsorption energy values are found to be
along the edges between two neighbouring (111)/(111) and (111)/(100) facets;
while FCC and HCP sites located on the (111) facets may show a chemisorption
value lower 0.3 eV where often fast O$_2$ dissociation easily occurs. Our
results show that, even though it is difficult to disentangle the geometrical
and electronic effects on the oxygen molecule adsorption, there is a strong
correlation between the calculated general coordination number (GCN) and the
chemisorp- tion map. Finally, the inclusion of dispersion corrections (DFT-D)
leads to an overall increase on the calculated adsorption energy values but
with a negligible alteration on the general O$_2$ adsorption trends.


title: Framed motives of relative motivic spheres

abstract:
  The category of framed correspondences $Fr_*(k)$ and framed sheaves were
invented by Voevodsky in his unpublished notes [V2]. Based on the theory,
framed motives are introduced and studied in [GP1]. These are Nisnivich sheaves
of $S^1$-spectra and the major computational tool of [GP1]. The aim of this
paper is to show the following result which is essential in proving the main
theorem of [GP1]: given an infinite perfect base field $k$, any $k$-smooth
scheme $X$ and any $n\geq 1$, the map of simplicial pointed Nisnevich sheaves
$(-,\mathbb{A}^1//\mathbb G_m)^{\wedge n}_+\to T^n$ induces a Nisnevich local
level weak equivalence of $S^1$-spectra
  $$M_{fr}(X\times (\mathbb{A}^1// \mathbb G_m)^{\wedge n})\to M_{fr}(X\times
T^n).$$ Moreover, it is proven that the sequence of $S^1$-spectra
  $$M_{fr}(X \times T^n \times \mathbb G_m) \to M_{fr}(X \times T^n
\times\mathbb A^1) \to M_{fr}(X \times T^{n+1})$$ is locally a homotopy cofiber
sequence in the Nisnevich topology. Another important result of this paper
shows that homology of framed motives is computed as linear framed motives in
the sense of [GP1]. This computation is crucial for the whole machinery of
framed motives [GP1].


title: Bacterial cartels at steady supply

abstract:
  Metagenomics has revealed hundreds of bacterial species in almost all
microbiota. In a few well-studied cases, bacterial communities have been
observed to coordinate their metabolic fluxes. In principle, bacteria can
divide tasks to reap the benefits of specialization, as in human economies.
However, the benefits and stability of an economy of bacterial specialists are
far from obvious. Here, we physically model the population dynamics of bacteria
that compete for steadily supplied resources. Importantly, we explicitly model
the metabolic fluxes yielding cellular biomass production under the constraint
of a limited enzyme budget. In our framework, we find that population dynamics
generally leads to the coexistence of different metabolic types, which satisfy
an extended competitive exclusion principle (even allowing for adaptive
mutation). We establish that these consortia act as cartels, whereby population
dynamics pins down resource concentrations at values for which no other
strategy can invade. Finally, we propose that at steady supply, cartels of
competing strategies automatically yield maximum biomass, thereby achieving a
collective optimum.


title: Gone in Six Characters: Short URLs Considered Harmful for Cloud Services

abstract:
  Modern cloud services are designed to encourage and support collaboration. To
help users share links to online documents, maps, etc., several services,
including cloud storage providers such as Microsoft OneDrive and mapping
services such as Google Maps, directly integrate URL shorteners that convert
long, unwieldy URLs into short URLs, consisting of a domain such as 1drv.ms or
goo.gl and a short token.
  In this paper, we demonstrate that the space of 5- and 6-character tokens
included in short URLs is so small that it can be scanned using brute-force
search. Therefore, all online resources that were intended to be shared with a
few trusted friends or collaborators are effectively public and can be accessed
by anyone. This leads to serious security and privacy vulnerabilities.
  In the case of cloud storage, we focus on Microsoft OneDrive. We show how to
use short-URL enumeration to discover and read shared content stored in the
OneDrive cloud, including even files for which the user did not generate a
short URL. 7% of the OneDrive accounts exposed in this fashion allow anyone to
write into them. Since cloud-stored files are automatically copied into users'
personal computers and devices, this is a vector for large-scale, automated
malware injection.
  In the case of online maps, we show how short-URL enumeration reveals the
directions that users shared with each other. For many individual users, this
enables inference of their residential addresses, true identities, and
extremely sensitive locations they visited that, if publicly revealed, would
violate medical and financial privacy.


title:
Impurity-Induced Antiferromagnetic Domains in the Periodic Anderson
  Model

abstract:
  A central feature of the Periodic Anderson Model is the competition between
antiferromagnetism, mediated by the Ruderman-Kittel-Kasuya-Yosida interaction
at small conduction electron-local electron hybridization $V$, and singlet
formation at large $V$. At zero temperature, and in dimension $d>1$, these two
phases are separated by a quantum critical point $V_c$. We use Quantum Monte
Carlo simulations to explore the effect of impurities which have a local
hybridization $V_{*} < V_c$ in the AF regime which are embedded in a bulk
singlet phase with $V > V_c$. We measure the suppression of singlet
correlations and the antiferromagnetic correlations which form around the
impurity, as well as the size of the resulting domain. Our calculations agree
qualitatively with NMR measurements in CeCoIn$_{5-x}$Cd$_x$.


title: Generalized R-squared for Detecting Dependence

abstract:
  Detecting dependence between two random variables is a fundamental problem.
Although the Pearson correlation is effective for capturing linear dependency,
it can be entirely powerless for detecting nonlinear and/or heteroscedastic
patterns. We introduce a new measure, G-squared, to test whether two univariate
random variables are independent and to measure the strength of their
relationship. The G-squared is almost identical to the square of the Pearson
correlation coefficient, R-squared, for linear relationships with constant
error variance, and has the intuitive meaning of the piecewise R-squared
between the variables. It is particularly effective in handling nonlinearity
and heteroscedastic errors. We propose two estimators of G-squared and show
their consistency. Simulations demonstrate that G-squared estimates are among
the most powerful test statistics compared with several state-of-the-art
methods.


title: Correlated Equilibria for Approximate Variational Inference in MRFs

abstract:
  Almost all of the work in graphical models for game theory has mirrored
previous work in probabilistic graphical models. Our work considers the
opposite direction: Taking advantage of recent advances in equilibrium
computation for probabilistic inference. We present formulations of inference
problems in Markov random fields (MRFs) as computation of equilibria in a
certain class of game-theoretic graphical models. We concretely establishes the
precise connection between variational probabilistic inference in MRFs and
correlated equilibria. No previous work exploits recent theoretical and
empirical results from the literature on algorithmic and computational game
theory on the tractable, polynomial-time computation of exact or approximate
correlated equilibria in graphical games with arbitrary, loopy graph structure.
We discuss how to design new algorithms with equally tractable guarantees for
the computation of approximate variational inference in MRFs. Also, inspired by
a previously stated game-theoretic view of state-of-the-art tree-reweighed
(TRW) message-passing techniques for belief inference as zero-sum game, we
propose a different, general-sum potential game to design approximate
fictitious-play techniques. We perform synthetic experiments evaluating our
proposed approximation algorithms with standard methods and TRW on several
classes of classical Ising models (i.e., with binary random variables). We also
evaluate the algorithms using Ising models learned from the MNIST dataset. Our
experiments show that our global approach is competitive, particularly shinning
in a class of Ising models with constant, "highly attractive" edge-weights, in
which it is often better than all other alternatives we evaluated. With a
notable exception, our more local approach was not as effective. Yet, in
fairness, almost all of the alternatives are often no better than a simple
baseline: estimate 0.5.


title:
InnoPOL: an EMCCD imaging polarimeter and 85-element curvature AO system
  on the 3.6-m AEOS telescope for cost effective polarimetric speckle
  suppression

abstract:
  The Hokupa'a-85 curvature adaptive optics system components have been adapted
to create a new AO-corrected coud\'{e} instrument at the 3.67m Advanced
Electro-Optical System (AEOS) telescope. This new AO-corrected optical path is
designed to deliver an f/40 diffraction-limited focus at wavelengths longer
than 800nm. A new EMCCD-based dual-beam imaging polarimeter called InnoPOL has
been designed and is presently being installed behind this corrected f/40 beam.
The InnoPOL system is a flexible platform for optimizing polarimetric
performance using commercial solutions and for testing modulation strategies.
The system is designed as a technology test and demonstration platform as the
coud\'{e} path is built using off-the-shelf components wherever possible.
Models of the polarimetric performance after AO correction show that
polarization modulation at rates as slow as 200Hz can cause speckle
correlations in brightness and focal plane location sufficient enough to change
the speckle suppression behavior of the modulators. These models are also
verified by initial EMCCD scoring camera data at AEOS. Substantial instrument
trades and development efforts are explored between instrument performance
parameters and various polarimetric noise sources.


title:
Surface-plasmon resonances of arbitrarily shaped nanometallic structures
  in the small-screening-length limit

abstract:
  According to the hydrodynamic Drude model, surface-plasmon resonances of
metallic nanostructures blueshift owing to the nonlocal response of the metal's
electron gas. The screening length characterising the nonlocal effect is often
small relative to the overall dimensions of the metallic structure, which
enables us to derive a coarse-grained nonlocal description using matched
asymptotic expansions; a perturbation theory for the blueshifts of arbitrary
shaped nanometallic structures is then developed. The effect of nonlocality is
not always a perturbation and we present a detailed analysis of the "bonding"
modes of a dimer of nearly touching nanowires where the leading-order
eigenfrequencies and eigenmode distributions are shown to be a renormalisation
of those predicted assuming a local metal permittivity.


title: The $\theta=\infty$ conjecture implies the Riemann hypothesis

abstract: We show that the $\theta=\infty$ conjecture implies the Riemann hypothesis.


title:
Voltage-dependent spin flip in magnetically-substituted graphene
  nanoribbons: Toward the realization of graphene-based spintronic devices

abstract:
  We examine the possibility of using graphene nanoribbons (GNRs) with directly
substituted chromium atoms as spintronic device. Using density functional
theory, we simulate a voltage bias across a constructed GNR in a device setup,
where a magnetic dimer has been substituted into the lattice. Through this
first principles approach, we calculate the electronic and magnetic properties
as a function of Hubbard U, voltage, and magnetic configuration. By calculating
of the total energy of each magnetic configuration, we determine that initial
antiferromagnetic ground state flips to a ferromagnetic state with applied
bias. Mapping this transition point to the calculated conductance for the
system reveals that there is a distinct change in conductance through the GNR,
which indicates the possibility of a spin valve. We also show that this
corresponds to a distinct change in the induced magnetization within the
graphene.


title:
Sequential Necessary and Sufficient Conditions for Capacity Achieving
  Distributions of Channels with Memory and Feedback

abstract:
  We derive sequential necessary and sufficient conditions for any channel
input conditional distribution ${\cal
P}_{0,n}\triangleq\{P_{X_t|X^{t-1},Y^{t-1}}:~t=0,\ldots,n\}$ to maximize the
finite-time horizon directed information defined by $$C^{FB}_{X^n \rightarrow
Y^n} \triangleq \sup_{{\cal P}_{0,n}} I(X^n\rightarrow{Y^n}),~~~ I(X^n
\rightarrow Y^n) =\sum_{t=0}^n{I}(X^t;Y_t|Y^{t-1})$$ for channel distributions
$\{P_{Y_t|Y^{t-1},X_t}:~t=0,\ldots,n\}$ and
$\{P_{Y_t|Y_{t-M}^{t-1},X_t}:~t=0,\ldots,n\}$, where
$Y^t\triangleq\{Y_0,\ldots,Y_t\}$ and $X^t\triangleq\{X_0,\ldots,X_t\}$ are the
channel input and output random processes, and $M$ is a finite nonnegative
integer.
  \noi We apply the necessary and sufficient conditions to application examples
of time-varying channels with memory and we derive recursive closed form
expressions of the optimal distributions, which maximize the finite-time
horizon directed information. Further, we derive the feedback capacity from the
asymptotic properties of the optimal distributions by investigating the limit
$$C_{X^\infty \rightarrow Y^\infty}^{FB} \triangleq \lim_{n \longrightarrow
\infty} \frac{1}{n+1} C_{X^n \rightarrow Y^n}^{FB}$$ without any \'a priori
assumptions, such as, stationarity, ergodicity or irreducibility of the channel
distribution. The necessary and sufficient conditions can be easily extended to
a variety of channels with memory, beyond the ones considered in this paper.


title: Dynamical complexity in the quantum to classical transition

abstract:
  We study the dynamical complexity of an open quantum driven double-well
oscillator, mapping its dependence on effective Planck's constant
$\hbar_{eff}\equiv\beta$ and coupling to the environment, $\Gamma$. We study
this using stochastic Schrodinger equations, semiclassical equations, and the
classical limit equation. We show that (i) the dynamical complexity initially
increases with effective Hilbert space size (as $\beta$ decreases) such that
the most quantum systems are the least dynamically complex. (ii) If the
classical limit is chaotic, that is the most dynamically complex (iii) if the
classical limit is regular, there is always a quantum system more dynamically
complex than the classical system. There are several parameter regimes where
the quantum system is chaotic even though the classical limit is not. While
some of the quantum chaotic attractors are of the same family as the classical
limiting attractors, we also find a quantum attractor with no classical
counterpart. These phenomena occur in experimentally accessible regimes.


title: Boundary-layers for a Neumann problem at higher critical exponents

abstract:
  We consider the Neumann problem $$(P)\qquad - \Delta v + v= v^{q-1} \
\text{in }\ \mathcal{D}, \ v > 0 \ \text{in } \ \mathcal{D},\ \partial_\nu v =
0 \ \text{on } \partial\mathcal{D} ,$$ where $\mathcal{D} $ is an open bounded
domain in $\mathbb{R}^N,$ $\nu$ is the unit inner normal at the boundary and
$q>2.$ For any integer, $1\le h\le N-3,$ we show that, in some suitable domains
$\mathcal D,$ problem $(P)$ has a solution which blows-up along a
$h-$dimensional minimal submanifold of the boundary $\partial\mathcal D$ as $q$
approaches from either below or above the higher critical Sobolev exponent
${2(N-h)\over N-h-2}.$


title: Lattice Quantum Gravity and Asymptotic Safety

abstract:
  We study the nonperturbative formulation of quantum gravity defined via
Euclidean dynamical triangulations (EDT) in an attempt to make contact with
Weinberg's asymptotic safety scenario. We find that a fine-tuning is necessary
in order to recover semiclassical behavior. Such a fine-tuning is generally
associated with the breaking of a target symmetry by the lattice regulator; in
this case we argue that the target symmetry is the general coordinate
invariance of the theory. After introducing and fine-tuning a nontrivial local
measure term, we find no barrier to taking a continuum limit, and we find
evidence that four-dimensional, semiclassical geometries are recovered at long
distance scales in the continuum limit. We also find that the spectral
dimension at short distance scales is consistent with 3/2, a value that could
resolve the tension between asymptotic safety and the holographic entropy
scaling of black holes. We argue that the number of relevant couplings in the
continuum theory is one, once symmetry breaking by the lattice regulator is
accounted for. Such a theory is maximally predictive, with no adjustable
parameters. The cosmological constant in Planck units is the only relevant
parameter, which serves to set the lattice scale. The cosmological constant in
Planck units is of order 1 in the ultraviolet and undergoes renormalization
group running to small values in the infrared. If these findings hold up under
further scrutiny, the lattice may provide a nonperturbative definition of a
renormalizable quantum field theory of general relativity with no adjustable
parameters and a cosmological constant that is naturally small in the infrared.


title: Properties of minimally $t$-tough graphs

abstract:
  A graph $G$ is minimally $t$-tough if the toughness of $G$ is $t$ and the
deletion of any edge from $G$ decreases the toughness. Kriesell conjectured
that for every minimally $1$-tough graph the minimum degree $\delta(G)=2$. We
show that in every minimally $1$-tough graph $\delta(G)\le\frac{n+2}{3}$. We
also prove that every minimally $1$-tough claw-free graph is a cycle. On the
other hand, we show that for every $t \in \mathbb{Q}$ any graph can be embedded
as an induced subgraph into a minimally $t$-tough graph.


title: Cooperative Interference Mitigation Algorithm in Heterogeneous Networks

abstract:
  Heterogeneous hetworks (HetNets) have been introduced as an emerging
technology in order to meet the increasing demand for mobile data. HetNets are
a combination of multi-layer networks such as macrocells and small cells. In
such networks, users may suffer significant cross-layer interference. To manage
this interference, the 3rd Generation Partnership Project (3GPP) has introduced
enhanced Inter-Cell Interference Coordination (eICIC) techniques. Almost Blank
SubFrame (ABSF) is one of the time-domain techniques used in eICIC solutions.
We propose a dynamically optimal Signal-to-Interference-and-Noise Ratio
(SINR)-based ABSF framework to ensure macro user performance while maintaining
small user performance. We also study cooperative mechanisms to help small
cells collaborate efficiently in order to reduce mutual interference.
Simulations show that our proposed scheme achieves good performance and
outperforms the existing ABSF frameworks.


title: TGIF: A New Dataset and Benchmark on Animated GIF Description

abstract:
  With the recent popularity of animated GIFs on social media, there is need
for ways to index them with rich metadata. To advance research on animated GIF
understanding, we collected a new dataset, Tumblr GIF (TGIF), with 100K
animated GIFs from Tumblr and 120K natural language descriptions obtained via
crowdsourcing. The motivation for this work is to develop a testbed for image
sequence description systems, where the task is to generate natural language
descriptions for animated GIFs or video clips. To ensure a high quality
dataset, we developed a series of novel quality controls to validate free-form
text input from crowdworkers. We show that there is unambiguous association
between visual content and natural language descriptions in our dataset, making
it an ideal benchmark for the visual content captioning task. We perform
extensive statistical analyses to compare our dataset to existing image and
video description datasets. Next, we provide baseline results on the animated
GIF description task, using three representative techniques: nearest neighbor,
statistical machine translation, and recurrent neural networks. Finally, we
show that models fine-tuned from our animated GIF description dataset can be
helpful for automatic movie description.


title:
Phase-Field Model of Cell Motility: Traveling Waves and Sharp Interface
  Limit

abstract:
  This letter is concerned with asymptotic analysis of a PDE model for motility
of a eukaryotic cell on a substrate. This model was introduced in [1], where it
was shown numerically that it successfully reproduces experimentally observed
phenomena of cell-motility such as a discontinuous onset of motion and shape
oscillations. The model consists of a parabolic PDE for a scalar phase-field
function coupled with a vectorial parabolic PDE for the actin filament network
(cytoskeleton). We formally derive the sharp interface limit (SIL), which
describes the motion of the cell membrane and show that it is a volume
preserving curvature driven motion with an additional nonlinear term due to
adhesion to the substrate and protrusion by the cytoskeleton. In a 1D model
problem we rigorously justify the SIL, and, using numerical simulations,
observe some surprising features such as discontinuity of interface velocities
and hysteresis. We show that nontrivial traveling wave solutions appear when
the key physical parameter exceeds a certain critical value and the potential
in the equation for phase field function possesses certain asymmetry.


title:
Joint In-Band Backhauling and Interference Mitigation in 5G
  Heterogeneous Networks

abstract:
  In this paper, we study the problem of joint inband backhauling and
interference mitigation in 5G heterogeneous networks (HetNets) in which a
massive multiple-input multipleoutput (MIMO) macro cell base station equipped
with a large number of antennas, overlaid with self-backhauled small cells is
assumed. This problem is cast as a network utility maximization subject to
wireless backhaul constraints. Due to the non-tractability of the problem, we
first resort to random matrix theory to get a closed-form expression of the
achievable rate and transmit power in the asymptotic regime, i.e., as the
number of antennas and users grows large. Subsequently, leveraging the
framework of stochastic optimization, the problem is decoupled into dynamic
scheduling of macro cell users and backhaul provisioning of small cells as a
function of interference and backhaul links. Via simulations, we evaluate the
performance gains of our proposed framework under different network
architectures and low/high frequency bands. Our proposed HetNet method achieves
the achievable average UE throughput of 1.7 Gbps as well as ensures 1 Gbps
cell-edge UE throughput when serving 200 UEs per km2 at 28 GHz with 1 GHz
bandwidth. In ultra-dense network, the UE throughput at 28 GHz achieves 62x
gain as compared to 2.4 GHz.


title:
$C_6$ coefficients and dipole polarizabilities for all atoms and many
  ions in rows 1-6 of the periodic table

abstract:
  Using time-dependent density functional theory (tdDFT) with exchange kernels
we calculate and test imaginary frequency-dependent dipole polarizabilities for
all atoms and many ns in rows 1-6 of the periodic table. These are then
integrated over frequency to produce $C_6$ coefficients. Results are presented
under different models: straight tdDFT calculations using two different
kernels, "benchmark" tdDFT calculations corrected by more accurate quantum
chemical and experimental data, and "benchmark" tdDFT with frozen orbital
anions. Parametrisations are presented for 411+ atoms and ions, allowing
results to be easily used by other researchers. A curious relationship,
$C_{6,XY}\propto [\alpha_X(0)\alpha_Y(0)]^{0.73}$ is found between $C_6$
coefficients and static polarizabilities $\alpha(0)$. The relationship
$C_{6,XY}=2C_{6,X}C_{6,Y}/[\alpha_X/\alpha_YC_{6,Y}+\alpha_Y/\alpha_XC_{6,X}]$
is tested and found to work well ($<5$\% errors) in about 80\% of cases, but
can break down badly ($>30$\% errors) in a small fraction of cases.


title: Performance Trade-Offs in Multi-Processor Approximate Message Passing

abstract:
  We consider large-scale linear inverse problems in Bayesian settings. Our
general approach follows a recent line of work that applies the approximate
message passing (AMP) framework in multi-processor (MP) computational systems
by storing and processing a subset of rows of the measurement matrix along with
corresponding measurements at each MP node. In each MP-AMP iteration, nodes of
the MP system and its fusion center exchange lossily compressed messages
pertaining to their estimates of the input. There is a trade-off between the
physical costs of the reconstruction process including computation time,
communication loads, and the reconstruction quality, and it is impossible to
simultaneously minimize all the costs. We pose this minimization as a
multi-objective optimization problem (MOP), and study the properties of the
best trade-offs (Pareto optimality) in this MOP. We prove that the achievable
region of this MOP is convex, and conjecture how the combined cost of
computation and communication scales with the desired mean squared error. These
properties are verified numerically.


title: Line Complexity Asymptotics of Polynomial Cellular Automata

abstract:
  Cellular automata are discrete dynamical systems that consist of patterns of
symbols on a grid, which change according to a locally determined transition
rule. In this paper, we will consider cellular automata that arise from
polynomial transition rules, where the symbols in the automaton are integers
modulo some prime $p$. We are principally concerned with the asymptotic
behavior of the line complexity sequence $a_T(k)$, which counts, for each $k$,
the number of coefficient strings of length $k$ that occur in the automaton. We
begin with the modulo $2$ case. For a given polynomial $T(x) = c_0 + c_1x + ...
+ c_nx^n$ with $c_0,c_n\neq 0$, we construct odd and even parts of the
polynomial from the strings $0c_1c_3c_5...$ and $c_0c_2c_4...$, respectively.
We prove that for polynomials for which the odd and even parts are relatively
prime, $a_T(k)$ satisfies recursions of a specific form. We also consider
powers of transition rules modulo $p$, introducing a notion of the order of a
recursion. We show that the property of "having a recursion of some order" is
preserved when the transition rule is raised to a positive integer power.
Extending to a more general setting, we investigate the asymptotics of $a_T(k)$
by considering an abstract generating function
$\phi(z)=\sum_{k=1}^\infty\alpha(k)z^k$ which satisfies a general functional
equation relating $\phi(z)$ and $\phi(z^p)$ for some prime $p$. We show that
there is a continuous, piecewise quadratic function $f$ on $[1/p, 1]$ for which
$\lim_{k\to\infty}(\alpha(k)/k^2 - f(p^{-\langle\log_p k\rangle})) = 0$, where
$\langle y\rangle$ denotes the fractional part of $y$. We use this result to
show that for certain positive integer sequences $s_k\to\infty$ with a
parameter $x\in [1/p,1]$, the ratio $\alpha(s_k(x))/s_k(x)^2$ tends to $f(x)$,
and that the limit superior and inferior of $\alpha(k)/k^2$ are given by the
extremal values of $f$.


title: Characterization of Hybrid Modes in Metamaterial Waveguides

abstract:
  In this paper, we employ the properties of metamaterials to tailor the modes
of metamaterial-dielectric waveguides operating at optical frequencies. We
survey the effect of fishnet metamaterial structural parameters such as the
magnetic oscillation strength, magnetic resonance frequency and magnetic
damping on the double-negative refractive index frequency region in
metamaterials and on the hybrid-modes in slab metamaterial-dielectric
waveguides. To identify the robustness of the metamaterials to fluctuations in
the metamaterial structural parameters, we investigate the behavior of
metamaterials under Gaussian errors on their structural parameters. Our survey
enables the identification of appropriate metamaterial unit-cell structure and
the permissive fluctuations on the structural parameters for further
applications of metamaterials in waveguide technologies.


title: A New Method for Constructing Circuit Codes

abstract:
  Circuit codes are constructed from induced cycles in the graph of the $n$
dimensional hypercube. They are both theoretically and practically important,
as circuit codes can be used as error correcting codes. When constructing
circuit codes, the length of the cycle determines its accuracy and a parameter
called the spread determines how many errors it can detect. We present a new
method for constructing a circuit code of spread $k+1$ from a circuit code of
spread $k$. This method leads to record code lengths for circuit codes of
spread $k=7 \text{ and } 8$ in dimension $22\le n\le 30$. We also derive a new
lower bound on the length of circuit codes of spread 4, improving upon the
current bound for dimension $n\ge 86$.


title:
The $a_0(980)$ and $\Lambda(1670)$ in the $\Lambda^+_c \to \pi^+ \eta
  \Lambda$ decay

abstract:
  We propose to study the $a_0(980)$ and the $\Lambda(1670)$ resonances in the
$\Lambda^+_c \to \pi^+ \eta \Lambda$ decay via the final state interactions of
the $\pi^+ \eta$ and $\eta \Lambda$ pairs. The weak interaction part proceeds
through the $c$ quark decay process: $c(ud) \to (s + u + \bar d)(ud)$, while
the hadronization part takes place in two different mechanisms. In the first
mechanism, the $sud$ cluster picks up a $q\bar{q}$ pair from the vacuum to form
the $\eta\Lambda$ meson-baryon pair while the $u\bar{d}$ pair from the weak
decay hadronizes into a $\pi^+$. In the second, the $sud$ cluster turns into a
$\Lambda$, while the $u\bar{d}$ pair from the $c$ decay picks up a $q\bar{q}$
pair and hadronizes into a meson-meson pair ($\pi\eta$ or $K\bar{K}$). Because
the final $\pi^+ \eta$ and $\eta \Lambda$ states are in pure isospin $I = 1$
and $I=0$ combinations, the $\Lambda^+_c \to \pi^+ \eta \Lambda$ decay can be
an ideal process to study the $a_0(980)$ and $\Lambda(1670)$ resonances.
Describing the final state interaction in the chiral unitary approach, we find
that the $\pi^+ \eta$ and $\eta \Lambda$ invariant mass distributions, up to an
arbitrary normalization, show clear cusp and peak structures, which can be
associated with the $a_0(980)$ and $\Lambda(1670)$ resonances, respectively.
The proposed mechanism can provide valuable information on the nature of these
resonances and can in principle be test by facilities such as BEPCII.


title: G\"odel on Deduction

abstract:
  This is an examination, a commentary, of links between some philosophical
views ascribed to G\"odel and general proof theory. In these views deduction is
of central concern not only in predicate logic, but in set theory too,
understood from an infinitistic ideal perspective. It is inquired whether this
centrality of deduction could also be kept in the intensional logic of concepts
whose building G\"odel seems to have taken as the main task of logic for the
future.


title: Derivations and the first cohomology group of trivial extension algebras

abstract:
  In this paper we investigate in details derivations on trivial extension
algebras. We obtain generalizations of both known results on derivations on
triangular matrix algebras and a known result on first cohomology group of
trivial extension algebras. As a consequence we get the characterization of
trivial extension algebras on which every derivation is inner. We show that,
under some conditions, a trivial extension algebra on which every derivation is
inner has necessarily a triangular matrix representation. The paper starts with
detailed study (with examples) of the relation between the trivial extension
algebras and the triangular matrix algebras.


title: Reconstruction of Order Flows using Aggregated Data

abstract:
  In this work we investigate tick-by-tick data provided by the TRTH database
for several stocks on three different exchanges (Paris - Euronext, London and
Frankfurt - Deutsche B\"orse) and on a 5-year span. We use a simple algorithm
that helps the synchronization of the trades and quotes data sources, providing
enhancements to the basic procedure that, depending on the time period and the
exchange, are shown to be significant. We show that the analysis of the
performance of this algorithm turns out to be a a forensic tool assessing the
quality of the aggregated database: we are able to track through the data some
significant technical changes that occurred on the studied exchanges. We also
illustrate the fact that the choices made when reconstructing order flows have
consequences on the quantitative models that are calibrated afterwards on such
data. Our study also provides elements on the trade signature, and we are able
to give a more refined look at the standard Lee-Ready procedure, giving new
elements on the way optimal lags should be chosen when using this method. The
findings are in line with both financial reasoning and the analysis of an
illustrative Poisson model of the order flow.


title:
Jorgensen's Inequality and Purely Loxodromic 2-Generator Free Kleinian
  Groups

abstract:
  Let $\xi$ and $\eta$ be two non--commuting isometries of the hyperbolic
$3$--space $\mathbb{H}^3$ so that $\Gamma=\langle\xi,\eta\rangle$ is a purely
loxodromic free Kleinian group. For $\gamma\in\Gamma$ and $z\in\mathbb{H}^3$,
let $d_{\gamma}z$ denote the distance between $z$ and $\gamma\cdot z$. Let
$z_1$ and $z_2$ be the mid-points of the shortest geodesic segments connecting
the axes of $\xi$, $\eta\xi\eta^{-1}$ and $\eta^{-1}\xi\eta$, respectively. In
this manuscript it is proved that if $d_{\gamma}z_2<1.6068...$ for every
$\gamma\in\{\eta, \xi^{-1}\eta\xi, \xi\eta\xi^{-1}\}$ and
$d_{\eta\xi\eta^{-1}}z_2\leq d_{\eta\xi\eta^{-1}}z_1$, then \[
|\text{trace}^2(\xi)-4|+|\text{trace}(\xi\eta\xi^{-1}\eta^{-1})-2|\geq
2\sinh^2\left(\tfrac{1}{4}\log\alpha\right) = 1.5937.... \] Above
$\alpha=24.8692...$ is the unique real root of the polynomial $21 x^4 - 496 x^3
- 654 x^2 + 24 x + 81$ that is greater than $9$. Also generalisations of this
inequality for finitely generated purely loxodromic free Kleinian groups are
conjectured.


title: Tractable Lineages on Treelike Instances: Limits and Extensions

abstract:
  Query evaluation on probabilistic databases is generally intractable
(#P-hard). Existing dichotomy results have identified which queries are
tractable (or safe), and connected them to tractable lineages. In our previous
work, using different tools, we showed that query evaluation is linear-time on
probabilistic databases for arbitrary monadic second-order queries, if we bound
the treewidth of the instance.
  In this paper, we study limitations and extensions of this result. First, for
probabilistic query evaluation, we show that MSO tractability cannot extend
beyond bounded treewidth: there are even FO queries that are hard on any
efficiently constructible unbounded-treewidth class of graphs. This dichotomy
relies on recent polynomial bounds on the extraction of planar graphs as
minors, and implies lower bounds in non-probabilistic settings, for query
evaluation and match counting in subinstance-closed families. Second, we show
how to explain our tractability result in terms of lineage: the lineage of MSO
queries on bounded-treewidth instances can be represented as bounded-treewidth
circuits, polynomial-size OBDDs, and linear-size d-DNNFs. By contrast, we can
strengthen the previous dichotomy to lineages, and show that there are even
UCQs with disequalities that have superpolynomial OBDDs on all
unbounded-treewidth graph classes; we give a characterization of such queries.
Last, we show how bounded-treewidth tractability explains the tractability of
the inversion-free safe queries: we can rewrite their input instances to have
bounded-treewidth.


title: Graviton laser

abstract:
  We consider the possibility of creating a graviton laser. The lasing medium
would be a system of contained, ultra cold neutrons. Ultra cold neutrons are a
quantum mechanical system that interacts with gravitational fields and with the
phonons of the container walls. It is possible to create a population inversion
by pumping the system using the phonons. We compute the rate of spontaneous
emission of gravitons and the rate of the subsequent stimulated emission of
gravitons. The gain obtainable is directly proportional to the density of the
lasing medium and the fraction of the population inversion. The applications of
a graviton laser would be interesting.


title:
Topological conjugacy of topological Markov shifts and Cuntz-Krieger
  algebras

abstract:
  For an irreducible non-permutation matrix $A$, the triplet
$({{\mathcal{O}}_A},{{\mathcal{D}}_A},\rho^A)$ for the Cuntz-Krieger algebra
${{\mathcal{O}}_A}$, its canonical maximal abelian $C^*$-subalgebra
${{\mathcal{D}}_A}$, and its gauge action $\rho^A$ is called the Cuntz-Krieger
triplet. We introduce a notion of strong Morita equivalence in the
Cuntz-Krieger triplets, and prove that two Cuntz-Krieger triplets
$({{\mathcal{O}}_A},{{\mathcal{D}}_A},\rho^A)$ and
$({{\mathcal{O}}_B},{{\mathcal{D}}_B},\rho^B)$ are strong Morita equivalent if
and only if $A$ and $B$ are strong shift equivalent.
  We also show that the generalized gauge actions on the stabilized
Cuntz-Krieger algebras are cocycle conjugate if the underlying matrices are
strong shift equivalent. By clarifying K-theoretic behavior of the cocycle
conjugacy, we investigate a relationship between cocycle conjugacy of the gauge
actions on the stabilized Cuntz-Krieger algebras and topological conjugacy of
the underlying topological Markov shifts.


title: On a cluster category of type $D_{\infty}$

abstract:
  We study the canonical orbit category of the bounded derived category of
finite dimensional representations of the quiver of type $D_{\infty}$. We prove
that this orbit category is a cluster category, that is, its cluster-tilting
subcategories form a cluster structure as defined in [\ref{BIRS}].


title:
Study of Distributed Spectrum Estimation Using Alternating Mixed
  Discrete-Continuous Adaptation

abstract:
  This paper proposes a distributed alternating mixed discrete-continuous
(DAMDC) algorithm to approach the oracle algorithm based on the diffusion
strategy for parameter and spectrum estimation over sensor networks. A least
mean squares (LMS) type algorithm that obtains the oracle matrix adaptively is
developed and compared with the existing sparsity-aware and conventional
algorithms. The proposed algorithm exhibits improved performance in terms of
mean square deviation and power spectrum estimation accuracy. Numerical results
show that the DAMDC algorithm achieves excellent performance.


title: Unified Theory of Magnetoelastic Effects in B20 chiral magnets

abstract:
  A magnetic skyrmion is a spin whirl with topological protection and high
mobility to electric current. Intrinsic magnetoelastic coupling in chiral
magnets permits manipulation of magnetic skyrmions and their lattice using
mechanical loads, which is essential for developing future spintronics devices.
It is found in experiments that the stability and deformation of skyrmions are
sensitive to stresses, while the appearance of magnetic skyrmions in turn has a
significant effect on the mechanical properties of the underlying material.
However, a theory which explains these related phenomena within a unified
framework is not seen. Here we construct a thermodynamic model for B20
helimagnets incorporating a magnetoelastic functional with necessary higher
order interactions derived by group theory. Within the model, we establish the
methodology to calculate the phase diagram and equilibrium properties of
helimagnets under coupled temperature-magneto-elastic field. Applying the model
to bulk MnSi, we calculate the temperature-magnetic field phase diagram under
stress-free condition and its variation when uniaxial compression is applied.
We also calculate the variation of all the elastic constants with magnetic
field. The results obtained agree quantitatively with corresponding
experiments. Our model provides a reliable basis for further theoretical
studies concerning any magnetoelastic related phenomena in chiral magnets.


title: Reversible "triple-Q" elastic field structures in a chiral magnet

abstract:
  The analytical solution of the periodic elastic field in chiral magnets
caused by presence of periodically distributed eigenstrains is obtained. For
the skyrmion phase, both the periodic displacement field and the stress field
are composed of three "triple-Q" structures with different wave numbers. We
find that for increasing external magnetic field, one type of "triple-Q"
displacement structure and stress structure undergo a configurational reversal,
where the initial and the final field configuration share similar pattern but
with opposite direction of all the field vectors. This result is enlightening
for designing novel skyrmion-based data-storage devices and microwave
applications. The solution obtained is of fundamental significance for
understanding the emergent mechanical properties of skyrmions in chiral
magnets.


title: Isoperimetric Regions in Nonpositively Curved Manifolds

abstract:
  Isoperimetric regions minimize the size of their boundaries among all regions
with the same volume. In Euclidean and Hyperbolic space, isoperimetric regions
are round balls. We show that isoperimetric regions in two and
three-dimensional nonpositively curved manifolds are not necessarily balls, and
need not even be connected.


title: Computable performance guarantees for compressed sensing matrices

abstract:
  The null space condition for $\ell_1$ minimization in compressed sensing is a
necessary and sufficient condition on the sensing matrices under which a sparse
signal can be uniquely recovered from the observation data via $\ell_1$
minimization. However, verifying the null space condition is known to be
computationally challenging. Most of the existing methods can provide only
upper and lower bounds on the proportion parameter that characterizes the null
space condition. In this paper, we propose new polynomial-time algorithms to
establish upper bounds of the proportion parameter. We leverage on these
techniques to find upper bounds and further develop a new procedure - tree
search algorithm - that is able to precisely and quickly verify the null space
condition. Numerical experiments show that the execution speed and accuracy of
the results obtained from our methods far exceed those of the previous methods
which rely on Linear Programming (LP) relaxation and Semidefinite Programming
(SDP).


title:
Giant modulation of the magnetic domain size induced by an electric
  field

abstract:
  The electric field (EF) effect on the magnetic domain structure of a Pt/Co
system was studied, where an EF was applied to the top surface of the Co layer.
The width of the maze domain was significantly modified by the application of
the EF at a temperature slightly below the Curie temperature. After a detailed
analysis, a change in the exchange stiffness induced by the EF application was
suggested to dominate the modulation of the domain width observed in the
experiment. The accumulation of electrons at the surface of the Co layer
resulted in an increase of the exchange stiffness and the Curie temperature.
The result was consistent with the recent theoretical prediction.


title: Thermalized connectivity networks of jammed packings

abstract:
  Jammed packings of repulsive elastic spheres have emerged as a rich model
system within which elastic properties of disordered glassy materials may be
elucidated. Most of the work on these packings have focused on the case of
vanishing temperature. Here, we explore the elastic properties of the
associated connectivity network for finite temperatures, ignoring the breaking
of bonds and the formation of new ones. Using extensive Monte Carlo
simulations, we find that, as the temperature is increased, the resulting
spring network shrinks and exhibits a rapidly softening bulk modulus via a
cusp. Moreover, the shear modulus stiffens in a fixed volume ensemble but not
in a fixed pressure ensemble. These counter-intuitive behaviors may be
understood from the characteristic spectrum of soft modes near isostaticity,
which resembles the spectrum of a rod near its buckling instability. Our
results suggest a generic mechanism for negative thermal expansion coefficients
in marginal solids. We discuss the consequences of bond breaking and an
apparent analogy between thermalization and shear.


title:
A construction method for discrete constant negative Gaussian curvature
  surfaces

abstract:
  This article is an application of the author's paper about a construction
method for discrete constant negative Gaussian curvature surfaces, the
nonlinear d'Alembert formula. The heart of this formula is the Birkhoff
decomposition, and we give a simple algorithm for the Birkhoff decomposition.
As an application, we draw figures of discrete constant negative Gaussian
curvature surfaces given by this method.


title: Overview of recent ALICE results

abstract:
  The ALICE experiment explores the properties of strongly interacting QCD
matter at extremely high temperatures created in Pb-Pb collisions at LHC and
provides further insight into small-system physics in (high-multiplicity) pp
and p-Pb collisions. The ALICE collaboration presented 27 parallel talks, 50
posters, and 1 flash talk at Quark Matter 2015 and covered various topics
including collective dynamics, correlations and fluctuations, heavy flavors,
quarkonia, jets and high $p_{\rm T}$ hadrons, electromagnetic probes, small
system physics, and the upgrade program. This paper highlights some of the
selected results.


title:
Reverse Engineering and Symbolic Knowledge Extraction on {\L}ukasiewicz
  Fuzzy Logics using Linear Neural Networks

abstract:
  This work describes a methodology to combine logic-based systems and
connectionist systems. Our approach uses finite truth valued {\L}ukasiewicz
logic, where we take advantage of fact what in this type of logics every
connective can be define by a neuron in an artificial network having by
activation function the identity truncated to zero and one. This allowed the
injection of first-order formulas in a network architecture, and also
simplified symbolic rule extraction.
  Our method trains a neural network using Levenderg-Marquardt algorithm, where
we restrict the knowledge dissemination in the network structure. We show how
this reduces neural networks plasticity without damage drastically the learning
performance. Making the descriptive power of produced neural networks similar
to the descriptive power of {\L}ukasiewicz logic language, simplifying the
translation between symbolic and connectionist structures.
  This method is used in the reverse engineering problem of finding the formula
used on generation of a truth table for a multi-valued {\L}ukasiewicz logic.
For real data sets the method is particularly useful for attribute selection,
on binary classification problems defined using nominal attribute. After
attribute selection and possible data set completion in the resulting
connectionist model: neurons are directly representable using a disjunctive or
conjunctive formulas, in the {\L}ukasiewicz logic, or neurons are
interpretations which can be approximated by symbolic rules. This fact is
exemplified, extracting symbolic knowledge from connectionist models generated
for the data set Mushroom from UCI Machine Learning Repository.


title:
Strain enhanced superconductivity of Mo$X_2$ ($X$=S or Se) bilayers with
  Na intercalation

abstract:
  Mo$X_2$ ($X$=S or Se) is a semiconductor family with two-dimensional
structure. And a recent calculation predicted the superconductivity in electron
doped MoS$_2$ monolayer. In this work, the electronic structure and lattice
dynamics of Mo$X_2$ bilayers with monolayer Na intercalated, have been
calculated. According to the electron-phonon interaction, it is predicted that
these bilayers can be transformed from indirect-gap semiconductors to a
superconductors by Na intercalation. More interestingly, the biaxial tensile
strain can significantly enhance the superconducting temperature up to $\sim10$
K in Na-intercalated MoS$_2$. In addition, the phonon mean free path at
room-temperature is also greatly improved in Na intercalated MoSe$_2$, which is
advantaged for related applications.


title: Five Essays on the Geometry of L\'aszl\'o Fejes T\'oth

abstract:
  In this paper we consider the following topics related to results of
L\'aszl\'o Fejes T\'oth: (1) The Tammes problem and Fejes T\'oth's bound on
circle packings; (2) Fejes T\'oth's problem on maximizing the minimum distance
between antipodal pairs of points on the sphere; (3) Fejes T\'oth's problem on
the maximum kissing number of packings on the sphere; (4) The Fejes T\'oth --
Sachs problem on the one--sided kissing numbers; (5) Fejes T\'oth's papers on
the isoperimetric problem for polyhedra.


title: Study of nonlocal correlations in macroscopic measurement scenario

abstract:
  Nonlocality is one of the main characteristic features of quantum systems
involving more than one spatially separated subsystems. It is manifested
theoretically as well as experimentally through violation of some local
realistic inequality. On the other hand, classical behavior of all physical
phenomena in the macroscopic limit gives a general intuition that any physical
theory for describing microscopic phenomena should resemble classical physics
in the macroscopic regime-- the so-called macro-realism. In the 2-2-2 scenario
(two parties, each performing two measurements, each measurement with two
outcomes), contemplating all the no-signaling correlations, we characterize
which of them would exhibit classical (local-realistic) behavior in the
macroscopic limit. Interestingly, we find correlations which at single copy
level violate the Bell-Clauser-Horne-Shimony-Holt inequality by an amount less
than optimal quantum violation (i.e. the Cirel'son bound $2\sqrt{2}$), but in
the macroscopic limit gives rise to a value which is higher than $2\sqrt{2}$.
Such correlations are therefore not considered as physical. Our study thus
provides a sufficient criterion to identify some of unphysical correlations.


title: Trends toward real-time network data steganography

abstract:
  Network steganography has been a well-known covert data channeling method for
over three decades. The basic set of techniques and implementation tools have
not changed significantly since their introduction in the early 1980's. In this
paper, we review the predominant methods of classical network steganography,
describing the detailed operations and resultant challenges involved in
embedding data in the network transport domain. We also consider the various
cyber threat vectors of network steganography and point out the major
differences between classical network steganography and the widely known
end-point multimedia embedding techniques, which focus exclusively on static
data modification for data hiding. We then challenge the security community by
introducing an entirely new network dat hiding methodology, which we refer to
as real-time network data steganography. Finally we provide the groundwork for
this fundamental change of covert network data embedding by forming a basic
framework for real-time network data operations that will open the path for
even further advances in computer network security.


title:
On one-loop entanglement entropy of two short intervals from OPE of
  twist operators

abstract:
  We investigate the one-loop entanglement entropy of two short intervals with
small cross ratio $x$ on a complex plane in two-dimensional conformal field
theory (CFT) using operator product expansion of twist operators. We focus on
the one-loop entanglement entropy instead of the general order $n$ R\'enyi
entropy, and this makes the calculation much easier. We consider the
contributions of stress tensor to order $x^{10}$, contributions of $W_3$
operator to order $x^{12}$, and contributions of $W_4$ operator to order
$x^{14}$. The CFT results agree with the ones in gravity.