title: An entropic characterization of long memory stationary process

abstract:
  Long memory or long range dependency is an important phenomenon that may
arise in the analysis of time series or spatial data. Most of the definitions
of long memory of a stationary process $X=\{X_1, X_2,\cdots,\}$ are based on
the second-order properties of the process. The excess entropy of a stationary
process is the summation of redundancies which relates to the rate of
convergence of the conditional entropy $H(X_n|X_{n-1},\cdots, X_1)$ to the
entropy rate. It is proved that the excess entropy is identical to the mutual
information between the past and the future when the entropy $H(X_1)$ is
finite. We suggest the definition that a stationary process is long memory if
the excess entropy is infinite. Since the definition of excess entropy of a
stationary process requires very weak moment condition on the distribution of
the process, it can be applied to processes whose distributions without bounded
second moment. A significant property of excess entropy is that it is invariant
under invertible transformation, which enables us to know the excess entropy of
a stationary process from the excess entropy of other process. For stationary
Guassian process, the excess entropy characterization of long memory relates to
popular characterization well. It is proved that the excess entropy of
fractional Gaussian noise is infinite if the Hurst parameter $H \in (1/2, 1)$.


title: Variations on a theme by Higman

abstract:
  We propose elementary and explicit presentations of groups that have no
amenable quotients and yet are SQ-universal. Examples include groups with a
finite classifying space, no Kazhdan subgroups and no Haagerup quotients.


title:
A hybrid approach for cooperative output regulation with sampled
  compensator

abstract:
  This work investigates the cooperative output regulation problem of linear
multi-agent systems with hybrid sampled data control. Due to the limited data
sensing and communication, in many practical situations, only sampled data are
available for the cooperation of multi-agent systems. To overcome this problem,
a distributed hybrid controller is presented for the cooperative output
regulation, and cooperative output regulation is achieved by well designed
state feedback law. Then it proposed a method for the designing of sampled data
controller to solve the cooperative output regulation problem with continuous
linear systems and discrete-time communication data. Finally, numerical
simulation example for cooperative tracking and a simulation example for
optimal control of micro-grids are proposed to illustrate the result of the
sampled data control law.


title:
Hybrid copula mixed models for combining case-control and cohort studies
  in meta-analysis of diagnostic tests

abstract:
  Copula mixed models for trivariate (or bivariate) meta-analysis of diagnostic
test accuracy studies accounting (or not) for disease prevalence have been
proposed in the biostatistics literature to synthesize information. However,
many systematic reviews often include case-control and cohort studies, so one
can either focus on the bivariate meta-analysis of the case control studies or
the trivariate meta-analysis of the cohort studies, as only the latter contains
information on disease prevalence. In order to remedy this situation of wasting
data we propose a hybrid copula mixed model via a combination of the bivariate
and trivariate copula mixed model for the data from the case-control studies
and cohort studies, respectively. Hence, this hybrid model can account for
study design and also due its generality can deal with dependence in the joint
tails. We apply the proposed hybrid copula mixed model to a review of the
performance of contemporary diagnostic imaging modalities for detecting
metastases in patients with melanoma.


title:
Multichannel Scattering and Loss Processes of Ultracold Atoms in
  Anisotropic Harmonic Waveguides

abstract:
  We have developed the general grid method for multi-channel scattering of
bosonic atoms inside a harmonic waveguide with transverse anisotropy. This
approach is employed to analyze elastic as well as inelastic multi-channel
confined scattering. For the elastic scattering, the effects of the range and
form of interatomic potential and the waveguide anisotropy on the confinement
induced resonance are studied. We have also investigated quantitatively the
reactive rate constant in confined atom-atom collisions. It is found that a
slight anisotropy to the confining trap considerably enhances the reactive rate
constant in multi-channel regime.


title: Character sheaves on neutrally solvable groups

abstract:
  Let $G$ be an algebraic group over an algebraically closed field $\mathtt{k}$
of characteristic $p>0$. In this paper we develop the theory of character
sheaves on groups $G$ such that their neutral connected components $G^\circ$
are solvable algebraic groups. For such algebraic groups $G$ (which we call
neutrally solvable) we will define the set $\operatorname{CS}(G)$ of character
sheaves on $G$ as certain special (isomorphism classes of) objects in the
category $\mathscr{D}_G(G)$ of $G$-equivariant
$\overline{\mathbb{Q}}_\ell$-complexes (where we fix a prime $\ell\neq p$) on
$G$. We will describe a partition of the set $\operatorname{CS}(G)$ into finite
sets known as $\mathbb{L}$-packets and we will associate a modular category
$\mathscr{M}_L$ with each $\mathbb{L}$-packet $L$ of character sheaves using a
truncated version of convolution of character sheaves. In the case where
$\mathtt{k}=\overline{\mathbb{F}}_q$ and $G$ is equipped with an
$\mathbb{F}_q$-Frobenius $F$ we will study the relationship between $F$-stable
character sheaves on $G$ and the irreducible characters of (all pure inner
forms of) $G^F$. In particular, we will prove that the notion of almost
characters (introduced by T. Shoji using Shintani descent) is well defined for
neutrally solvable groups and that these almost characters coincide with the
"trace of Frobenius" functions associated with $F$-stable character sheaves. We
will also prove that the matrix relating the irreducible characters and almost
characters is block diagonal where the blocks on the diagonal are parametrized
by $F$-stable $\mathbb{L}$-packets. Moreover, we will prove that the block in
this transition matrix corresponding to any $F$-stable $\mathbb{L}$-packet $L$
can be described as the crossed S-matrix associated with the auto-equivalence
of the modular category $\mathscr{M}_L$ induced by $F$.


title: An Online Structural Plasticity Rule for Generating Better Reservoirs

abstract:
  In this article, a novel neuro-inspired low-resolution online unsupervised
learning rule is proposed to train the reservoir or liquid of Liquid State
Machine. The liquid is a sparsely interconnected huge recurrent network of
spiking neurons. The proposed learning rule is inspired from structural
plasticity and trains the liquid through formation and elimination of synaptic
connections. Hence, the learning involves rewiring of the reservoir connections
similar to structural plasticity observed in biological neural networks. The
network connections can be stored as a connection matrix and updated in memory
by using Address Event Representation (AER) protocols which are generally
employed in neuromorphic systems. On investigating the 'pairwise separation
property' we find that trained liquids provide 1.36 $\pm$ 0.18 times more
inter-class separation while retaining similar intra-class separation as
compared to random liquids. Moreover, analysis of the 'linear separation
property' reveals that trained liquids are 2.05 $\pm$ 0.27 times better than
random liquids. Furthermore, we show that our liquids are able to retain the
'generalization' ability and 'generality' of random liquids. A memory analysis
shows that trained liquids have 83.67 $\pm$ 5.79 ms longer fading memory than
random liquids which have shown 92.8 $\pm$ 5.03 ms fading memory for a
particular type of spike train inputs. We also throw some light on the dynamics
of the evolution of recurrent connections within the liquid. Moreover, compared
to 'Separation Driven Synaptic Modification' - a recently proposed algorithm
for iteratively refining reservoirs, our learning rule provides 9.30%, 15.21%
and 12.52% more liquid separations and 2.8%, 9.1% and 7.9% better
classification accuracies for four, eight and twelve class pattern recognition
tasks respectively.


title:
Selfish Computation Offloading for Mobile Cloud Computing in Dense
  Wireless Networks

abstract:
  Offloading computation to a mobile cloud is a promising solution to augment
the computation capabilities of mobile devices. In this paper we consider
selfish mobile devices in a dense wireless network, in which individual mobile
devices can offload computations via multiple access points (APs) to a mobile
cloud so as to minimize their computation costs, and we provide a game
theoretical analysis of the problem. We show that in the case of an elastic
cloud, all improvement paths are finite, and thus a pure strategy Nash
equilibrium exists and can be computed easily. In the case of a non-elastic
cloud we show that improvement paths may cycle, yet we show that a pure Nash
equilibrium exists and we provide an efficient algorithm for computing one.
Furthermore, we provide an upper bound on the price of anarchy (PoA) of the
game. We use simulations to evaluate the time complexity of computing Nash
equilibria and to provide insights into the PoA under realistic scenarios. Our
results show that the equilibrium cost may be close to optimal, and the cost
difference is due to too many mobile users offloading simultaneously.


title: Horizontal $\alpha$-Harmonic Maps

abstract:
  Given a $C^1$ planes distribution $P_T$ on all ${\mathbb R}^m$ we consider
{\em horizontal $\alpha$-harmonic maps}, $\alpha\ge 1/2$, with respect to such
a distribution. These are maps $u\in H^{\alpha}({{\mathbb R}}^k,{{\mathbb
R}}^m)$ satisfying $P_T\nabla u=\nabla u$ and $P_T(u)(-\Delta)^{\alpha}u=0$ in
${\mathcal D}'({{\mathbb R}}^k).$
  If the distribution of planes is integrable then we recover the classical
case of $\alpha$-harmonic maps with values into a manifold. In this paper we
shall focus our attention to the case $\alpha=1/2$ in dimension $1$ and
$\alpha=2$ in dimension $2$ and we investigate the regularity of the {\em
horizontal $\alpha$-harmonic maps}. In both cases we show that such maps
satisfy a Schr\"odinger type system with an antisymmetric potential, that
permits us to apply the previous results obtained by the authors. Finally we
study the regularity of {\em variational $\alpha$-harmonic} maps which are
critical points of $\|(-\Delta)^{\alpha/2} u\|^2_{L^2}$ under the constraint to
be tangent (horizontal) to a given planes distribution. We produce a
convexification of this variational problem which permits to write it's Euler
Lagrange equations.


title: Ensemble Enabled Weighted PageRank

abstract:
  This paper describes our solution for WSDM Cup 2016. Ranking the query
independent importance of scholarly articles is a critical and challenging
task, due to the heterogeneity and dynamism of entities involved. Our approach
is called Ensemble enabled Weighted PageRank (EWPR). To do this, we first
propose Time-Weighted PageRank that extends PageRank by introducing a time
decaying factor. We then develop an ensemble method to assemble the authorities
of the heterogeneous entities involved in scholarly articles. We finally
propose to use external data sources to further improve the ranking accuracy.
Our experimental study shows that our EWPR is a good choice for ranking
scholarly articles.


title: OGLE-2012-BLG-0724Lb: A Saturn-mass Planet around an M-dwarf

abstract:
  We report the discovery of a planet by the microlensing method,
OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this
event was one of the shortest seen for a planetary event, the anomaly was well
covered thanks to high cadence observations taken by the survey groups OGLE and
MOA. By analyzing the light curve, this planetary system is found to have a
mass ratio $q=(1.58\pm0.15)\times10^{-3}$. By conducting a Bayesian analysis,
we estimate that the host star is an M-dwarf star with a mass of $M_{\rm
L}=0.29_{-0.16}^{+0.33} \ M_{\odot}$ located at $D_{\rm L}=6.7_{-1.2}^{+1.1} \
{\rm kpc}$ away from the Earth and the companion's mass is $m_{\rm
P}=0.47_{-0.26}^{+0.54} \ M_{\rm Jup}$. The projected planet-host separation is
$a_{\perp}=1.6_{-0.3}^{+0.4} \ {\rm AU}$. Because the lens-source relative
proper motion is relatively high, future high resolution images would detect
the lens host star and determine the lens properties uniquely. This system is
likely a Saturn-mass exoplanet around an M-dwarf and such systems are commonly
detected by gravitational microlensing. This adds an another example of a
possible pileup of sub-Jupiters $(0.2 < m_{\rm P}/M_{\rm Jup} < 1)$ in contrast
to a lack of Jupiters ($\sim 1 - 2 \ M_{\rm Jup}$) around M-dwarfs, supporting
the prediction by core accretion models that Jupiter-mass or more massive
planets are unlikely to form around M-dwarfs.


title: Fluid Limit of a PS-queue with Multistage Service

abstract:
  The PS-model treated in this paper is motivated by freelance job websites
where multiple freelancers compete for a single job. In the context of such
websites, multistage service of a job means collection of applications from
multiple freelancers. Under Markovian stochastic assumptions, we develop fluid
limit approximations for the PS-model in overload. Based on this approximation,
we estimate what proportion of freelancers get the jobs they apply for. In
addition, the PS-model studied here is an instant of PS with routing and
impatience, for which no Lyapunov function is known, and we suggest some
partial solutions.


title: CUORE-0 detector: design, construction and operation

abstract:
  The CUORE experiment will search for neutrinoless double-beta decay of
$^{130}$Te with an array of 988 TeO$_2$ bolometers arranged in 19 towers.
CUORE-0, the first tower assembled according to the CUORE procedures, was built
and commissioned at Laboratori Nazionali del Gran Sasso, and took data from
March 2013 to March 2015. In this paper we describe the design, construction
and operation of the CUORE-0 experiment, with an emphasis on the improvements
made over a predecessor experiment, Cuoricino. In particular, we demonstrate
with CUORE-0 data that the design goals of CUORE are within reach.


title: On extension functions for image space with different separation axioms

abstract:
  In this paper we study a sufficient conditions for continuous and almost
continuous extensions of f to space X for an image space Y with different
separation axioms.


title: Folded Goursat surface and banana-shaped seedpod

abstract:
  Thin vegetal shells have recently been a significant source of inspiration
for the de\text{sign} of smart materials and soft actuators. Herein is
presented a novel analytical family of isometric deformations with folds,
inspired by a banana-shaped seedpod, which converts a vertical closing into
either an horizontal closing or an opening depending on the location of the
fold. Similarly to the seedpod, optimum shapes for opening ease are the most
elongated ones.


title:
Understanding Rating Behaviour and Predicting Ratings by Identifying
  Representative Users

abstract:
  Online user reviews describing various products and services are now abundant
on the web. While the information conveyed through review texts and ratings is
easily comprehensible, there is a wealth of hidden information in them that is
not immediately obvious. In this study, we unlock this hidden value behind user
reviews to understand the various dimensions along which users rate products.
We learn a set of users that represent each of these dimensions and use their
ratings to predict product ratings. Specifically, we work with restaurant
reviews to identify users whose ratings are influenced by dimensions like
'Service', 'Atmosphere' etc. in order to predict restaurant ratings and
understand the variation in rating behaviour across different cuisines. While
previous approaches to obtaining product ratings require either a large number
of user ratings or a few review texts, we show that it is possible to predict
ratings with few user ratings and no review text. Our experiments show that our
approach outperforms other conventional methods by 16-27% in terms of RMSE.


title: Hot subdwarf stars and their connection to thermonuclear supernovae

abstract:
  Hot subdwarf stars (sdO/Bs) are evolved core helium-burning stars with very
thin hydrogen envelopes, which can be formed by common envelope ejection. Close
sdB binaries with massive white dwarf (WD) companions are potential progenitors
of thermonuclear supernovae type Ia (SN Ia). We discovered such a progenitor
candidate as well as a candidate for a surviving companion star, which escapes
from the Galaxy. More candidates for both types of objects have been found by
crossmatching known sdB stars with proper motion and light curve catalogues.
The Gaia mission will provide accurate astrometry and light curves of all the
stars in our hot subdwarf sample and will allow us to compile a much larger
all-sky catalogue of those stars. In this way we expect to find hundreds of
progenitor binaries and ejected companions.


title: Inversion of Stokes Profiles with Systematic Effects

abstract:
  Quantitative thermodynamical, dynamical and magnetic properties of the solar
and stellar plasmas are obtained by interpreting their emergent non-polarized
and polarized spectrum. This inference requires the selection of a set of
spectral lines particularly sensitive to the physical conditions in the plasma
and a suitable parametric model of the solar/stellar atmosphere. Nonlinear
inversion codes are then used to fit the model to the observations. However,
the presence of systematic effects like nearby or blended spectral lines,
telluric absorption or incorrect correction of the continuum, among others, can
strongly affect the results. We present an extension to current inversion codes
that can deal with these effects in a transparent way. The resulting algorithm
is very simple and can be applied to any existing inversion code with the
addition of a few lines of code as an extra step in each iteration.


title: Managing Overstaying Electric Vehicles in Park-and-Charge Facilities

abstract:
  With the increase in adoption of Electric Vehicles (EVs), proper utilization
of the charging infrastructure is an emerging challenge for service providers.
Overstaying of an EV after a charging event is a key contributor to low
utilization. Since overstaying is easily detectable by monitoring the power
drawn from the charger, managing this problem primarily involves designing an
appropriate "penalty" during the overstaying period. Higher penalties do
discourage overstaying; however, due to uncertainty in parking duration, less
people would find such penalties acceptable, leading to decreased utilization
(and revenue). To analyze this central trade-off, we develop a novel framework
that integrates models for realistic user behavior into queueing dynamics to
locate the optimal penalty from the points of view of utilization and revenue,
for different values of the external charging demand. Next, when the model
parameters are unknown, we show how an online learning algorithm, such as UCB,
can be adapted to learn the optimal penalty. Our experimental validation, based
on charging data from London, shows that an appropriate penalty can increase
both utilization and revenue while significantly reducing overstaying.


title:
Demand Prediction and Placement Optimization for Electric Vehicle
  Charging Stations

abstract:
  Effective placement of charging stations plays a key role in Electric Vehicle
(EV) adoption. In the placement problem, given a set of candidate sites, an
optimal subset needs to be selected with respect to the concerns of both (a)
the charging station service provider, such as the demand at the candidate
sites and the budget for deployment, and (b) the EV user, such as charging
station reachability and short waiting times at the station. This work
addresses these concerns, making the following three novel contributions: (i) a
supervised multi-view learning framework using Canonical Correlation Analysis
(CCA) for demand prediction at candidate sites, using multiple datasets such as
points of interest information, traffic density, and the historical usage at
existing charging stations; (ii) a mixed-packing-and- covering optimization
framework that models competing concerns of the service provider and EV users;
(iii) an iterative heuristic to solve these problems by alternately invoking
knapsack and set cover algorithms. The performance of the demand prediction
model and the placement optimization heuristic are evaluated using real world
data.


title:
Fast algorithms for large scale generalized distance weighted
  discrimination

abstract:
  High dimension low sample size statistical analysis is important in a wide
range of applications. In such situations, the highly appealing discrimination
method, support vector machine, can be improved to alleviate data piling at the
margin. This leads naturally to the development of distance weighted
discrimination (DWD), which can be modeled as a second-order cone programming
problem and solved by interior-point methods when the scale (in sample size and
feature dimension) of the data is moderate. Here, we design a scalable and
robust algorithm for solving large scale generalized DWD problems. Numerical
experiments on real data sets from the UCI repository demonstrate that our
algorithm is highly efficient in solving large scale problems, and sometimes
even more efficient than the highly optimized LIBLINEAR and LIBSVM for solving
the corresponding SVM problems.


title:
Biochemical machines for the interconversion of mutual information and
  work

abstract:
  We propose a physically-realisable biochemical device that is coupled to a
biochemical reservoir of mutual information, fuel molecules and a chemical
bath. Mutual information allows work to be done on the bath even when the fuel
molecules appear to be in equilibrium; alternatively, mutual information can be
created by driving from the fuel or the bath. The system exhibits diverse
behaviour, including a regime in which the information, despite increasing
during the reaction, enhances the extracted work. We further demonstrate that a
modified device can function without the need for external manipulation,
eliminating the need for a complex and potentially costly control.


title:
Probing the Dzyaloshinskii-Moriya interaction in CoFeB ultrathin films
  using domain wall creep and Brillouin light spectroscopy

abstract:
  We have characterized the strength of the interfacial Dyzaloshinskii-Moriya
interaction (DMI) in ultrathin perpendicularly magnetized CoFeB/MgO films,
grown on different underlayers of W, TaN, and Hf, using two experimental
methods. First, we determined the effective DMI field from measurements of
field-driven domain wall motion in the creep regime, where applied in-plane
magnetic fields induce an anisotropy in the wall propagation that is correlated
with the DMI strength. Second, Brillouin light spectroscopy was employed to
quantify the frequency non-reciprocity of spin waves in the CoFeB layers, which
yielded an independent measurement of the DMI. By combining these results, we
show that DMI estimates from the different techniques only yield qualitative
agreement, which suggests that open questions remain on the underlying models
used to interpret these results.


title: From Control System Security Indices to Attack Identifiability

abstract:
  In this paper, we investigate detectability and identifiability of attacks on
linear dynamical systems that are subjected to external disturbances. We
generalize a concept for a security index, which was previously introduced for
static systems. The generalized index exactly quantifies the resources
necessary for targeted attacks to be undetectable and unidentifiable in the
presence of disturbances. This information is useful for both risk assessment
and for the design of anomaly detectors. Finally, we show how techniques from
the fault detection literature can be used to decouple disturbances and to
identify attacks, under certain sparsity constraints.


title:
Reentrant condensation transition in a two species driven diffusive
  system

abstract:
  We study an interacting box-particle system on a one-dimensional periodic
ring involving two species of particles $A$ and $B$. In this model, from a
randomly chosen site, a particle of species $A$ can hop to its right neighbor
with a rate that depends on the number of particles of the species $B$ at that
site. On the other hand, particles of species $B$ can be transferred between
two neighboring sites with rates that depends on the number of particles of
species $B$ at the two adjacent sites$-$this process however can occur only
when the two sites are devoid of particles of the species $A$. We study
condensation transition for a specific choice of rates and find that the system
shows a reentrant phase transition of species $A$ $-$ the species $A$ passes
successively through fluid-condensate-fluid phases as the coupling parameter
between the dynamics of the two species is varied. On the other hand, the
transition of species $B$ is from condensate to fluid phase and hence does not
show reentrant feature.


title:
Valid parameter space of a bivariate Gaussian Markov random field with a
  generalized block-Toeplitz precision matrix

abstract:
  Gaussian Markov random fields (GMRFs) are extensively used in statistics to
model area-based data and usually depend on several parameters in order to
capture complex spatial correlations. In this context, it is important to
determine the valid parameter space, namely the domain ensuring (semi)
positive-definiteness of the precision matrix. Depending on the structure of
the latter, this task can be challenging. While univari- ate GMRFs with
block-Toeplitz precision are well studied in the literature, not much is
analytically known about bivariate GMRFs. So far, only restrictive sufficient
conditions and brute-force approaches were proposed, which are computationally
expensive for the size of modern datasets. In this paper, we consider a
bivariate GMRF, which is part of a hierarchical model used in spatial
statistics to analyze data coming from projec- tions of regional climate
change. By extending classical convergence results of univariate fields with
toroidal boundary conditions to fields without boundary conditions, we pro-
vide asymptotically closed-form expressions of the valid parameter space. We
develop a general methodology that can be used to determine the valid parameter
space of bivariate GMRFs whose precision matrix has a generalized
block-Toeplitz structure and for which classical convergence results are not
directly applicable. Finally, we quantify the rate of convergence of our
approach through a numerical study in R.


title: A wearable haptic game controller

abstract:
  This paper outlines the development of a wearable game controller
incorporating vibrotacticle haptic feedback that provides a low cost, versatile
and intuitive interface for controlling digital games. The device differs from
many traditional haptic feedback implementation in that it combines
vibrotactile based haptic feedback with gesture based input, thus becoming a
two way conduit between the user and the virtual environment. The device is
intended to challenge what is considered an "interface" and draws on work in
the area of Actor-Network theory to purposefully blur the boundary between man
and machine. This allows for a more immersive experience, so rather than making
the user feel like they are controlling an aircraft the intuitive interface
allows the user to become the aircraft that is controlled by the movements of
the user's hand. This device invites playful action and thrill. It bridges new
territory on portable and low cost solutions for haptic controllers in a gaming
context.


title:
Energy-transport models for spin transport in ferromagnetic
  semiconductors

abstract:
  Explicit energy-transport equations for the spinorial carrier transport in
ferromagnetic semiconductors are calculated from a general spin
energy-transport system that was derived by Ben Abdallah and El Hajj from a
spinorial Boltzmann equation. The novelty of our approach are the simplifying
assumptions leading to explicit models which extend both spin drift-diffusion
and semiclassical energy-transport equations. The explicit models allow us to
examine the interplay between the spin and charge degrees of freedom. In
particular, the monotonicity of the entropy (or free energy) and gradient
estimates are shown for these models and the existence of weak solutions to a
time-discrete version of one of the models is proved, using novel truncation
arguments. Numerical experiments in one-dimensional multilayer structures using
a finite-volume discretization illustrate the effect of the temperature and the
polarization parameter.


title:
On Distributed Internal Model Principle for Output Regulation over
  Time-Varying Networks of Linear Heterogeneous Agents

abstract:
  We study a multi-agent output regulation problem, where not all agents have
access to the exosystem's dynamics. We propose a distributed controller that
solves the problem for linear, heterogeneous, and uncertain agent dynamics as
well as time-varying directed networks. The distributed controller consists of
two parts: (1) an exosystem generator that creates a local copy of the
exosystem dynamics by using consensus protocols, and (2) a dynamic compensator
that uses (again) consensus to approach the internal model of the exosystem and
thereby achieves perfect output regulation. Our approach leverages methods from
internal model based controller synthesis, multi-agent consensus over directed
networks, and stability of time-varying linear systems; the derived result is
an adaptation of the (centralized) internal model principle to the distributed,
networked setting.


title:
Geometry, supertransfer, and optimality in the light harvesting of
  purple bacteria

abstract:
  The remarkable rotational symmetry of the photosynthetic antenna complexes of
purple bacteria has long been thought to enhance their light harvesting and
excitation energy transport. We study the role of symmetry by modeling
hypothetical antennas whose symmetry is broken by altering the orientations of
the bacteriochlorophyll pigments. We find that in both LH2 and LH1 complexes,
symmetry increases energy transfer rates by enabling the cooperative, coherent
process of supertransfer. The enhancement is particularly pronounced in the LH1
complex, whose natural geometry outperforms the average randomized geometry by
5.5 standard deviations, the most significant coherence-related enhancement
found in a photosynthetic complex.


title: SWIPT in 3-D Bipolar Ad Hoc Networks with Sectorized Antennas

abstract:
  In this letter, we study the simultaneous wireless information and power
transfer (SWIPT) concept in 3-D bipolar ad hoc networks with spatial
randomness. Due to three spatial dimensions of the network, we introduce a 3-D
antenna sectorization that exploits the horizontal and the vertical spatial
separation. The impact of 3-D antenna sectorization on SWIPT performance is
evaluated for the power-splitting technique by using stochastic geometry tools.
Theoretical and numerical results show that 3-D sectorization achieves a more
accurate beam steering in the 3-D space, which can be beneficial for both the
information and the power transfer.


title: Preferred axis in cosmology

abstract:
  The foundation of modern cosmology relies on the so-called cosmological
principle which states an homogeneous and isotropic distribution of matter in
the universe on large scales. However, recent observations, such as the
temperature anisotropy of the cosmic microwave background (CMB) radiation, the
motion of galaxies in the universe, the polarization of quasars and the
acceleration of the cosmic expansion, indicate preferred directions in the sky.
If these directions have a cosmological origin, the cosmological principle
would be violated, and modern cosmology should be reconsidered. In this paper,
by considering the preferred axis in the CMB parity violation, we find that it
coincides with the preferred axes in CMB quadrupole and CMB octopole, and they
all align with the direction of the CMB kinematic dipole. In addition, the
preferred directions in the velocity flows, quasar alignment, anisotropy of the
cosmic acceleration, the handedness of spiral galaxies, and the angular
distribution of the fine-structure constant are also claimed to be aligned with
the CMB kinematic dipole. Since CMB dipole was confirmed to be caused by the
motion of our local group of galaxies relative to the reference frame of the
CMB, the coincidence of all these preferred directions hints that these
anomalies have a common origin, which is not cosmological or due to a
gravitational effect. The systematical or contaminative errors in observation
or in data analysis, which can be directly related to the motion of our local
group of galaxies, can play an important role in explaining the anomalies.


title:
Contractions with Polynomial Characteristic Functions II. Analytic
  Approach

abstract:
  The simplest and most natural examples of completely nonunitary contractions
on separable complex Hilbert spaces which have polynomial characteristic
functions are the nilpotent operators. The main purpose of this paper is to
prove the following theorem: Let $T$ be a completely nonunitary contraction on
a Hilbert space $\mathcal{H}$. If the characteristic function $\Theta_T$ of $T$
is a polynomial of degree $m$, then there exist a Hilbert space $\mathcal{M}$,
a nilpotent operator $N$ of order $m$, a coisometry $V_1 \in
\mathcal{L}(\overline{ran} (I - N N^*) \oplus \mathcal{M}, \overline{ran} (I -
T T^*))$, and an isometry $V_2 \in \mathcal{L}(\overline{ran} (I - T^* T),
\overline{ran} (I - N^* N) \oplus \mathcal{M})$, such that \[ \Theta_T = V_1
\begin{bmatrix} \Theta_N & 0 0 & I_{\mathcal{M}} \end{bmatrix} V_2. \]


title: Different lattice geometries with synthetic dimension

abstract:
  The possibility of creating different geometries with the help of an extra
synthetic dimension in optical lattices is studied. Additional linear potential
and Raman assisted tunnelings are used to engineer well controlled tunnelings
between available states. The great flexibility of the system allows us to
obtain different geometries of synthetic lattices with possibility of adding
synthetic gauge fields.


title: Acyclic Constraint Logic and Games

abstract:
  Non-deterministic Constraint Logic is a family of graph games introduced by
Demaine and Hearn that facilitates the construction of complexity proofs. It is
convenient for the analysis of games, providing a uniform view. We focus on the
acyclic version, apply this to Klondike, Mahjong Solitaire and Nonogram (that
requires planarity), and discuss the more complicated game of Dou Shou Qi.
While for the first three games we reobtain known characterizations in a simple
and uniform manner, the result for Dou Shou Qi is new.


title: Introduction to high-energy gamma-ray astronomy

abstract:
  The present issue is the first of of a two-volume review devoted to gamma-ray
astronomy above 100 MeV which has witnessed considerable progress over the last
20 years. The motivations for research in this area are explained, the
follow-on articles of these two thematic issues are introduced and a brief
history of the field is given.


title:
K-optimal designs for parameters of shifted Ornstein-Uhlenbeck processes
  and sheets

abstract:
  Continuous random processes and fields are regularly applied to model
temporal or spatial phenomena in many different fields of science, and model
fitting is usually done with the help of data obtained by observing the given
process at various time points or spatial locations. In these practical
applications sampling designs which are optimal in some sense are of great
importance. We investigate the properties of the recently introduced K-optimal
design for temporal and spatial linear regression models driven by
Ornstein-Uhlenbeck processes and sheets, respectively, and highlight the
differences compared with the classical D-optimal sampling. A simulation study
displays the superiority of the K-optimal design for large parameter values of
the driving random process.


title: Threshold models of cascades in large-scale networks

abstract:
  The spread of new beliefs, behaviors, conventions, norms, and technologies in
social and economic networks are often driven by cascading mechanisms, and so
are contagion dynamics in financial networks. Global behaviors generally emerge
from the interplay between the structure of the interconnection topology and
the local agents' interactions. We focus on the Linear Threshold Model (LTM) of
cascades first introduced by Granovetter (1978). This can be interpreted as the
best response dynamics in a network game whereby agents choose strategically
between two actions and their payoff is an increasing function of the number of
their neighbors choosing the same action. Each agent is equipped with an
individual threshold representing the number of her neighbors who must have
adopted a certain action for that to become the agent's best response. We
analyze the LTM dynamics on large-scale networks with heterogeneous agents.
Through a local mean-field approach, we obtain a nonlinear, one-dimensional,
recursive equation that approximates the evolution of the LTM dynamics on most
of the networks of a given size and distribution of degrees and thresholds.
Specifically, we prove that, on all but a fraction of networks with given
degree and threshold statistics that is vanishing as the network size grows
large, the actual fraction of adopters of a given action in the LTM dynamics is
arbitrarily close to the output of the aforementioned recursion. We then
analyze the dynamic behavior of this recursion and its bifurcations from a
dynamical systems viewpoint. Applications of our findings to some real network
testbeds show good adherence of the theoretical predictions to numerical
simulations.


title:
Asymptotic order of the quantization errors for self-affine measures on
  Bedford-McMullen carpets

abstract:
  Let $E$ be a Bedford-McMullen carpet determined by a set of affine mappings
$(f_{ij})_{(i,j)\in G}$ and $\mu$ a self-affine measure on $E$ associated with
a probability vector $(p_{ij})_{(i,j)\in G}$. We prove that, for every
$r\in(0,\infty)$, the upper and lower quantization coefficient are always
positive and finite in its exact quantization dimension $s_r$. As a
consequence, the $k$th quantization error for $\mu$ of order $r$ is of the same
order as $k^{-\frac{1}{s_r}}$. In sharp contrast to the Hausdorff measure for
Bedford-McMullen carpets, our result is independent of the horizontal fibres of
the carpets.


title: Count-Min Tree Sketch: Approximate counting for NLP

abstract:
  The Count-Min Sketch is a widely adopted structure for approximate event
counting in large scale processing. In a previous work we improved the original
version of the Count-Min-Sketch (CMS) with conservative update using
approximate counters instead of linear counters. These structures are
computationaly efficient and improve the average relative error (ARE) of a CMS
at constant memory footprint. These improvements are well suited for NLP tasks,
in which one is interested by the low-frequency items. However, if Log counters
allow to improve ARE, they produce a residual error due to the approximation.
In this paper, we propose the Count-Min Tree Sketch (Copyright 2016 eXenSa. All
rights reserved) variant with pyramidal counters, which are focused toward
taking advantage of the Zipfian distribution of text data.


title: Indirect Dark Matter Detection for Flattened Dwarf Galaxies

abstract:
  Gamma-ray experiments seeking to detect evidence of dark matter annihilation
in dwarf spheroidal galaxies require knowledge of the distribution of dark
matter within these systems. We analyze the effects of flattening on the
annihilation (J) and decay (D) factors of dwarf spheroidal galaxies with both
analytic and numerical methods. Flattening has two consequences: first, there
is a geometric effect as the squeezing (or stretching) of the dark matter
distribution enhances (or diminishes) the J-factor; second, the line of sight
velocity dispersion of stars must hold up the flattened baryonic component in
the flattened dark matter halo. We provide analytic formulae and a simple
numerical approach to estimate the correction to the J- and D-factors required
over simple spherical modeling. The formulae are validated with a series of
equilibrium models of flattened stellar distributions embedded in flattened
dark-matter distributions. We compute corrections to the J- and D-factors for
the Milky Way dwarf spheroidal galaxies under the assumption that they are all
prolate or all oblate and find that the hierarchy of J-factors for the dwarf
spheroidals is slightly altered (typical correction factors for an ellipticity
of $0.4$ are $0.75$ for the oblate case and $1.6$ for the prolate case). We
demonstrate that spherical estimates of the D-factors are very insensitive to
the flattening and introduce uncertainties significantly less than the
uncertainties in the D-factors from the other observables for all the dwarf
spheroidals (for example, ${}^{+10\mathrm{\,percent}}_{-3\mathrm{\,percent}}$
for a typical ellipticity of $0.4$). We conclude by investigating the spread in
correction factors produced by triaxial figures and provide uncertainties in
the J-factors for the dwarf spheroidals using different physically-motivated
assumptions for their intrinsic shape and axis alignments. (abridged)


title: On coefficient functionals associated with the Zalcman conjecture

abstract:
  We consider certain subfamilies, of the family of univalent functions in the
open unit disk, defined by means of sufficient coefficient conditions for
univalency. This article is devoted to studying the problem of the well-known
conjecture of Zalcman consisting of a generalized coefficient functional, the
so-called generalized Zalcman conjecture problem, for functions belonging to
those subfamilies. We estimate the bounds associated with the generalized
coefficient functional and show that the estimates are sharp.


title:
Deep Saliency with Encoded Low level Distance Map and High Level
  Features

abstract:
  Recent advances in saliency detection have utilized deep learning to obtain
high level features to detect salient regions in a scene. These advances have
demonstrated superior results over previous works that utilize hand-crafted low
level features for saliency detection. In this paper, we demonstrate that
hand-crafted features can provide complementary information to enhance
performance of saliency detection that utilizes only high level features. Our
method utilizes both high level and low level features for saliency detection
under a unified deep learning framework. The high level features are extracted
using the VGG-net, and the low level features are compared with other parts of
an image to form a low level distance map. The low level distance map is then
encoded using a convolutional neural network(CNN) with multiple 1X1
convolutional and ReLU layers. We concatenate the encoded low level distance
map and the high level features, and connect them to a fully connected neural
network classifier to evaluate the saliency of a query region. Our experiments
show that our method can further improve the performance of state-of-the-art
deep learning-based saliency detection methods.


title:
Calibration of LAMOST Stellar Surface Gravities Using the Kepler
  Asteroseismic Data

abstract:
  Asteroseismology is a powerful tool to precisely determine the evolutionary
status and fundamental properties of stars. With the unprecedented precision
and nearly continuous photometric data acquired by the NASA Kepler mission,
parameters of more than 10$^4$ stars have been determined nearly consistently.
However, most studies still use photometric effective temperatures (Teff) and
metallicities ([Fe/H]) as inputs, which are not sufficiently accurate as
suggested by previous studies. We adopted the spectroscopic Teff and [Fe/H]
values based on the LAMOST low-resolution spectra (R~1,800), and combined them
with the global oscillation parameters to derive the physical parameters of a
large sample of stars. Clear trends were found between {\Delta}logg(LAMOST -
seismic) and spectroscopic Teff as well as logg, which may result in an
overestimation of up to 0.5 dex for the logg of giants in the LAMOST catalog.
We established empirical calibration relations for the logg values of dwarfs
and giants. These results can be used for determining the precise distances to
these stars based on their spectroscopic parameters.


title:
Tunable and temporally stable ferroelectric imprint through polarization
  coupling

abstract:
  Here we demonstrate a method to tune ferroelectric imprint, which is stable
in time, based on the coupling between the non-switchable polarization of ZnO
and switchable polarization of PbZrxTi(1-x)O3. SrRuO3/PbZrxTi(1-x)O3
/ZnO/SrRuO3 heterostructures were grown with different ZnO thicknesses. It is
shown that the coercive voltages and ferroelectric imprint varies linearly with
the thickness of ZnO. It is also demonstrated that the ferroelectric imprint
remains stable with electric field cycling and electric field stress assisted
aging.


title: On isotropic cloaking and interior transmission eigenvalue problems

abstract:
  This paper is concerned with the invisibility cloaking in acoustic wave
scattering from a new perspective. We are especially interested in achieving
the invisibility cloaking by completely regular and isotropic mediums. It is
shown that an interior transmission eigenvalue problem arises in our study,
which is the one considered theoretically in \cite{CCH}. Based on such an
observation, we propose a cloaking scheme that takes a three-layer structure
including a cloaked region, a lossy layer and a cloaking shell. The target
medium in the cloaked region can be arbitrary but regular, whereas the mediums
in the lossy layer and the cloaking shell are both regular and isotropic. We
establish that if a certain non-transparency condition is satisfied, then there
exists an infinite set of incident waves such that the cloaking device is
nearly-invisible under the corresponding wave interrogation. The set of waves
is generated from the Herglotz-approximation of the associated interior
transmission eigenfunctions. We provide both theoretical and numerical
justifications.


title: Exploring Segment Representations for Neural Segmentation Models

abstract:
  Many natural language processing (NLP) tasks can be generalized into
segmentation problem. In this paper, we combine semi-CRF with neural network to
solve NLP segmentation tasks. Our model represents a segment both by composing
the input units and embedding the entire segment. We thoroughly study different
composition functions and different segment embeddings. We conduct extensive
experiments on two typical segmentation tasks: named entity recognition (NER)
and Chinese word segmentation (CWS). Experimental results show that our neural
semi-CRF model benefits from representing the entire segment and achieves the
state-of-the-art performance on CWS benchmark dataset and competitive results
on the CoNLL03 dataset.


title:
Radius of convexity of partial sums of odd functions in the
  close-to-convex family

abstract:
  We consider the class of all analytic and locally univalent functions $f$ of
the form $f(z)=z+\sum_{n=2}^\infty a_{2n-1} z^{2n-1}$, $|z|<1$, satisfying the
condition $$ {\rm Re}\,\left(1+\frac{zf^{\prime\prime}(z)}{f^\prime
(z)}\right)>-\frac{1}{2}. $$ We show that every section
$s_{2n-1}(z)=z+\sum_{k=2}^na_{2k-1}z^{2k-1}$, of $f$, is convex in the disk
$|z|<\sqrt{2}/3$. We also prove that the radius $\sqrt{2}/3$ is best possible,
i.e. the number $\sqrt{2}/3$ cannot be replaced by a larger one.


title: Revisiting the OH-CH correlation in diffuse clouds

abstract:
  Based on the analysis of available published data and archival data along 24
sightlines (5 of which are new) we derive more accurate estimates of the column
densities of OH and CH towards diffuse/translucent clouds and revisit the
typically observed correlation between the abundances of these species. The
increase in the sample size was possible because of the equivalence of the
column densities of CH derived from a combination of the transitions at 3137 &
3143 Angstrom, and a combination of transitions at 3886 & 3890 Angstrom, which
we have demonstrated here. We find that with the exception of four diffuse
clouds, the entire source sample shows a clear correlation between the column
densities of OH and CH similar to previous observations. The analysis presented
also verifies the theoretically predicted oscillator strengths of the OH A--X
(3078 & 3082 Angstrom), CH B--X (3886 & 3890 Angstrom) and C--X (3137 & 3143
Angstrom) transitions. We estimate N(H) and N(H2) from the observed E(B-V) and
N(CH) respectively. The N(OH)/N(CH) ratio is not correlated with the molecular
fraction of hydrogen in the diffuse/translucent clouds. We show that with the
exception of HD 34078 for all the clouds the observed column density ratios of
CH and OH can be reproduced by simple chemical models which include gas-grain
interaction and gas-phase chemistry. The enhanced N(OH)/N(CH) ratio seen
towards the 3 new sightlines can be reproduced primarily by considering
different cosmic ray ionization rates.


title: Pressure tuning the Fermi-surface topology of the Weyl semimetal NbP

abstract:
  We report on the pressure evolution of the Fermi surface topology of the Weyl
semimetal NbP, probed by Shubnikov-de Haas oscillations in the
magnetoresistance combined with ab-initio calculations of the band-structure.
Although we observe a drastic effect on the amplitudes of the quantum
oscillations, the frequencies only exhibit a weak pressure dependence up to 2.8
GPa. The pressure-induce variations in the oscillation frequencies are
consistent with our band-structure calculations. Furthermore, we can relate the
changes in the amplitudes to small modifications in the shape of the Fermi
surface. Our findings evidenced the stability of the electronic band structure
of NbP and demonstrate the power of combining quantum-oscillation studies and
band-structure calculations to investigate pressure effects on the
Fermi-surface topology in Weyl semimetals.


title:
Data stream mining for predicting software build outcomes using source
  code metrics

abstract:
  Software development projects involve the use of a wide range of tools to
produce a software artifact. Software repositories such as source control
systems have become a focus for emergent research because they are a source of
rich information regarding software development projects. The mining of such
repositories is becoming increasingly common with a view to gaining a deeper
understanding of the development process.


title: Polyhedral products, flag complexes and monodromy representations

abstract:
  This article presents a machinery based on polyhedral products that produces
faithful representations of graph products of finite groups and direct products
of finite groups into automorphisms of free groups $\rm Aut(F_n)$ and outer
automorphisms of free groups $\rm Out(F_n)$, respectively, as well as faithful
representations of products of finite groups into the linear groups $\rm
SL(n,\mathbb Z)$ and $\rm GL(n,\mathbb Z)$. These faithful representations are
realized as monodromy representations.


title: Vectorial Hankel operators, Carleson embeddings, and notions of $BMOA$

abstract:
  We consider operators of the type $D^\alpha:H^2(\mathcal{H})\to
H^2(\mathcal{H})$, where $D^\alpha$ denotes a fractional differentiation
operator, and $\Gamma_\phi$ is a Hankel operator. For $\alpha>0$, we
characterize boundedness in terms of a natural anti-analytic Carleson embedding
condition. We obtain three notable corollaries. The first is that our main
result does not extend to $\alpha=0$, i.e. Nehari-Page BMOA is not
characterized by the natural anti-analytic Carleson embedding condition. The
second is that when we add an adjoint embedding condition, we obtain a
sufficient but not necessary condition for boundedness of $\Gamma_\phi$. The
third is that there exists a bounded analytic function for which the associated
anti-analytic Carleson embedding is unbounded. As a consequence, boundedness of
an analytic Carleson embedding does not imply that the anti-analytic ditto is
bounded. This answers a question by Nazarov, Pisier, Treil, and Volberg.


title: Sparse domination of sharp variational truncations

abstract:
  We provide a versatile formulation of Lacey's recent sparse pointwise
domination technique with a local weak type estimate on a nontangential maximal
function as the only hypothesis. We verify this hypothesis for sharp
variational truncations of singular integrals in the case when unweighted $L^2$
estimates are available. This extends previously known sharp weighted estimates
for smooth variational truncations to the case of sharp variational
truncations. We also include a sparse domination result for iterated
commutators of multilinear operators with BMO functions.


title: The young centre of the Earth

abstract:
  We treat, as an illustrative example of gravitational time dilation in
relativity, the observation that the center of the Earth is younger than the
surface by an appreciable amount. Richard Feynman first made this insightful
point and presented an estimate of the size of the effect in a talk; a
transcription was later published in which the time difference is quoted as
'one or two days'. However, a back-of-the-envelope calculation shows that the
result is in fact a few years. In this paper we present this estimate alongside
a more elaborate analysis yielding a difference of two and a half years. The
aim is to provide a fairly complete solution to the relativity of the 'aging'
of an object due to differences in the gravitational potential. This solution -
accessible at the undergraduate level - can be used for educational purposes,
as an example in the classroom. Finally, we also briefly discuss why exchanging
'years' for 'days' - which in retrospect is a quite simple, but significant,
mistake - has been repeated seemingly uncritically, albeit in a few cases only.
The pedagogical value of this discussion is to show students that any number or
observation, no matter who brought it forward, must be critically examined.


title:
Intelligent Agent-Based Stimulation for Testing Robotic Software in
  Human-Robot Interactions

abstract:
  The challenges of robotic software testing extend beyond conventional
software testing. Valid, realistic and interesting tests need to be generated
for multiple programs and hardware running concurrently, deployed into dynamic
environments with people. We investigate the use of Belief-Desire-Intention
(BDI) agents as models for test generation, in the domain of human-robot
interaction (HRI) in simulations. These models provide rational agency,
causality, and a reasoning mechanism for planning, which emulate both
intelligent and adaptive robots, as well as smart testing environments directed
by humans. We introduce reinforcement learning (RL) to automate the exploration
of the BDI models using a reward function based on coverage feedback. Our
approach is evaluated using a collaborative manufacture example, where the
robotic software under test is stimulated indirectly via a simulated human
co-worker. We conclude that BDI agents provide intuitive models for test
generation in the HRI domain. Our results demonstrate that RL can fully
automate BDI model exploration, leading to very effective coverage-directed
test generation.


title: Strange duality on rational surfaces

abstract:
  We study Le Potier's strange duality conjecture on a rational surface. We
focus on the case involving the moduli space of rank 2 sheaves with trivial
first Chern class and second Chern class 2, and the moduli space of
1-dimensional sheaves with determinant $L$ and Euler characteristic 0. We show
the conjecture for this case is true under some suitable conditions on $L$,
which applies to $L$ ample on any Hirzebruch surface
$\Sigma_e:=\mathbb{P}(\mathcal{O}_{\mathbb{P}^1}\oplus\mathcal{O}_{\mathbb{P}^1}(e))$
except for $e=1$. When $e=1$, our result applies to $L=aG+bF$ with $b\geq
a+[a/2]$, where $F$ is the fiber class, $G$ is the section class with $G^2=-1$
and $[a/2]$ is the integral part of $a/2$.


title: Pebbling Meets Coloring: Reversible Pebble Game On Trees

abstract:
  The reversible pebble game is a combinatorial game played on rooted DAGs.
This game was introduced by Bennett (1989) motivated by applications in
designing space efficient reversible algorithms. Recently, Chan (2013) showed
that the reversible pebble game number of any DAG is the same as its
Dymond-Tompa pebble number and Raz-Mckenzie pebble number.
  We show, as our main result, that for any rooted directed tree T, its
reversible pebble game number is always just one more than the edge rank
coloring number of the underlying undirected tree U of T. It is known that
given a DAG G as input, determining its reversible pebble game number is
PSPACE-hard. Our result implies that the reversible pebble game number of trees
can be computed in polynomial time.
  We also address the question of finding the number of steps required to
optimally pebble various families of trees. It is known that trees can be
pebbled in $n^{O(\log(n))}$ steps where $n$ is the number of nodes in the tree.
Using the equivalence between reversible pebble game and the Dymond-Tompa
pebble game (Chan, 2013), we show that complete binary trees can be pebbled in
$n^{O(\log\log(n))}$ steps, a substantial improvement over the naive upper
bound of $n^{O(\log(n))}$. It remains open whether complete binary trees can be
pebbled in polynomial (in $n$) number of steps. Towards this end, we show that
almost optimal (i.e., within a factor of $(1 + \epsilon)$ for any constant
$\epsilon > 0$) pebblings of complete binary trees can be done in polynomial
number of steps.
  We also show a time-space trade-off for reversible pebbling for families of
bounded degree trees by a divide-and-conquer approach: for any constant
$\epsilon > 0$, such families can be pebbled using $O(n^\epsilon)$ pebbles in
$O(n)$ steps. This generalizes an analogous result of Kralovic (2001) for
chains.


title: Numerical design of nonuniform disk-loaded waveguides

abstract:
  On the base of modified mode matching method we obtain some results that can
be useful in the process of tuning of nonunifrom disk-loaded structures. Our
consideration has shown that there are some parameters that depend only on the
geometric sizes of sells and equals known values for the needed phase
distribution of the amplitudes of field expansion. Changing the geometric sized
in such way that these parameters will tend to a given values, we can
numerically design the structure that have the given phase distribution of
these amplitudes. We consider these tuning parameters as a good instrument
under simulation of inhomogeneous structures with sizes that usually used in
accelerators.


title: $n$-representations of Quivers

abstract:
  Let $n \geq 2$. We introduce the notion of $n$-representations of quivers,
and we explicitly provide concrete examples of $2$-representations of quivers.
We establish the categories of $n$-representations and investigate kernels and
cokernels in the categories of $n$-representations of quivers. Further, we
construct them in terms of kernels and cokernels of morphisms in the usual
categories of quiver representations. We show that every morphism in the
categories of $n$-representations has a canonical decomposition. Most
importantly, we prove that the categories of $n$-representations of quivers are
$k$-linear abelian categories.


title: Model independent analysis of nearly L\'evy correlations

abstract:
  A model-independent method for the analysis of the two-particle short-range
correlations is presented, that can be utilized to describe e.g. Bose-Einstein
(HBT), dynamical (ridge) or other correlation functions, that have a nearly
L\'evy or streched exponential shape. For the special case of L\'evy exponent
alpha = 1, the earlier Laguerre expansions are recovered, for the alpha = 2
special case, a new expansion method is obtained for nearly Gaussian
correlation functions. Multi-dimensional L\'evy expansions are also introduced
and their potential application to analyze rigde correlation data is discussed.

categories: physics.data-an hep-ex hep-ph nucl-ex nucl-th


title: New method of solving the many-body Schr\"odinger equation

abstract:
  A method of solving the Schr\"{o}dinger equation based on the use of constant
particle-particle interaction potential surfaces (IPS) is proposed. The
many-body wave function is presented in a configuration interaction form, with
coefficients depending on the total interaction potential. The corresponding
set of linear ordinary differential equations for the coefficients was
developed. To reduce the computational work, a hierarchy of approximations
based on interaction potential surfaces of a part of the particle system was
worked out. The solution of a simple exactly solvable model and He-like ions
proves that this method is more accurate than the conventional configuration
interaction method and demonstrates a better convergence with a basis set
increase.


title:
Ab initio Study of Aspirin Adsorption on Single-walled Carbon and Carbon
  Nitride Nanotubes

abstract:
  We use ab intio density functional theory to investigate the adsorption
properties of acetylsalicylic acid or aspirin on a (10, 0) carbon nanotube
(CNT) and a (8, 0) triazine-based graphitic carbon nitride nanotube (CNNT). It
is found that an aspirin molecule binds stronger to the CNNT with its
adsorption energy of 0.67 eV than to the CNT with 0.51 eV. The stronger
adsorption energy on the CNNT is ascribed to the high reactivity of its N atoms
with high electron affinity. The CNNT exhibits local electric dipole moments,
which cause strong charge redistribution in the aspirin molecule adsorbed on
the CNNT than on the CNT. We also explore the influence of an external electric
field on the adsorption properties of aspirin on these nanotubes by examining
the modifications in their electronic band structures, partial densities of
states, and charge distributions. It is found that an electric field applied
along a particular direction induces aspirin molecular states in the in-gap
region of the CNNT implying a potential application of aspirin detection.


title:
Right buffer sizing matters: some dynamical and statistical studies on
  Compound TCP

abstract:
  Motivated by recent concerns that queuing delays in the Internet are on the
rise, we conduct a performance evaluation of Compound TCP (C-TCP) in two
topologies: a single bottleneck and a multi-bottleneck topology, under
different traffic scenarios. The first topology consists of a single bottleneck
router, and the second consists of two distinct sets of TCP flows, regulated by
two edge routers, feeding into a common core router. We focus on some dynamical
and statistical properties of the underlying system. From a dynamical
perspective, we develop fluid models in a regime wherein the number of flows is
large, bandwidth-delay product is high, buffers are dimensioned small
(independent of the bandwidth-delay product) and routers deploy a Drop-Tail
queue policy. A detailed local stability analysis for these models yields the
following key insight: smaller buffers favour stability. Additionally, we
highlight that larger buffers, in addition to increasing latency, are prone to
inducing limit cycles in the system dynamics, via a Hopf bifurcation. These
limit cycles in turn cause synchronisation among the TCP flows, and also result
in a loss of link utilisation. For the topologies considered, we also
empirically analyse some statistical properties of the bottleneck queues. These
statistical analyses serve to validate an important modelling assumption: that
in the regime considered, each bottleneck queue may be approximated as either
an $M/M/1/B$ or an $M/D/1/B$ queue. This immediately makes the modelling
perspective attractive and the analysis tractable. Finally, we show that
smaller buffers, in addition to ensuring stability and low latency, would also
yield fairly good system performance, in terms of throughput and flow
completion times.


title:
Robust pricing--hedging duality for American options in discrete time
  financial markets

abstract:
  We investigate pricing-hedging duality for American options in discrete time
financial models where some assets are traded dynamically and others, e.g. a
family of European options, only statically. In the first part of the paper we
consider an abstract setting, which includes the classical case with a fixed
reference probability measure as well as the robust framework with a
non-dominated family of probability measures. Our first insight is that by
considering a (universal) enlargement of the space, we can see American options
as European options and recover the pricing-hedging duality, which may fail in
the original formulation. This may be seen as a weak formulation of the
original problem. Our second insight is that lack of duality is caused by the
lack of dynamic consistency and hence a different enlargement with dynamic
consistency is sufficient to recover duality: it is enough to consider
(fictitious) extensions of the market in which all the assets are traded
dynamically. In the second part of the paper we study two important examples of
robust framework: the setup of Bouchard and Nutz (2015) and the martingale
optimal transport setup of Beiglb\"ock et al. (2013), and show that our general
results apply in both cases and allow us to obtain pricing-hedging duality for
American options.


title: Constraints on galactic wind models

abstract:
  Observational implications are derived for two standard models of
supernovae-driven galactic winds: a freely expanding steady-state wind and a
wind sourced by a self-similarly expanding superbubble including thermal heat
conduction. It is shown that, for the steady-state wind, matching the measured
correlation between the soft x-ray luminosity and star formation rate of
starburst galaxies is equivalent to producing a scaled wind mass-loading factor
relative to the star-formation rate of 0.5 - 3, in agreement with the amount
inferred from metal absorption line measurements. The match requires the
asymptotic wind velocity v_inf to scale with the star formation rate SFR (in
solar masses per year) approximately as v_inf ~ (700 - 1000) km/s SFR^{1/6}.
The corresponding mass injection rate is close to the amount naturally provided
by thermal evaporation from the wall of a superbubble in a galactic disc,
suggesting thermal evaporation may be a major source of mass-loading. The
predicted mass-loading factors from thermal evaporation within the galactic
disc alone, however, are somewhat smaller, 0.2 - 2, so that a further
contribution from cloud ablation or evaporation may be required. Both models
may account for the 1.4GHz luminosity of unresolved radio sources within
starburst galaxies for plausible parameters describing the distribution of
relativistic electrons. Further observational tests to distinguish the models
are suggested.


title:
M$^2$S-Net: Multi-Modal Similarity Metric Learning based Deep
  Convolutional Network for Answer Selection

abstract:
  Recent works using artificial neural networks based on distributed word
representation greatly boost performance on various natural language processing
tasks, especially the answer selection problem. Nevertheless, most of the
previous works used deep learning methods (like LSTM-RNN, CNN, etc.) only to
capture semantic representation of each sentence separately, without
considering the interdependence between each other. In this paper, we propose a
novel end-to-end learning framework which constitutes deep convolutional neural
network based on multi-modal similarity metric learning (M$^2$S-Net) on
pairwise tokens. The proposed model demonstrates its performance by surpassing
previous state-of-the-art systems on the answer selection benchmark, i.e.,
TREC-QA dataset, in both MAP and MRR metrics.


title: Exact WKB Analysis of N = 2 Gauge Theories

abstract:
  We study N = 2 supersymmetric gauge theories with gauge group SU(2) coupled
to fundamental flavours, covering all asymptotically free and conformal cases.
We re-derive, from the conformal field theory perspective, the differential
equations satisfied by omega deformed instanton partition functions. We confirm
their validity at leading order in one of the deformation parameters via a
saddle-point analysis of the partition function. In the semi-classical limit we
show that these differential equations take a form amenable to exact WKB
analysis. We compute the monodromy group associated to the differential
equations in terms of deformed and Borel resummed Seiberg-Witten data. For each
case, we study pairs of Stokes graphs that are related by flips and pops, and
show that the monodromy groups allow one to confirm the Stokes automorphisms
that arise as the phase of the deformation parameter is varied. Finally, we
relate the Borel resummed monodromies with the traditional Seiberg-Witten
variables in the semi-classical limit.


title: Simple and accurate analytical calculation of shortest path lengths

abstract:
  We present an analytical approach to calculating the distribution of shortest
paths lengths (also called intervertex distances, or geodesic paths) between
nodes in unweighted undirected networks. We obtain very accurate results for
synthetic random networks with specified degree distribution (the so-called
configuration model networks). Our method allows us to accurately predict the
distribution of shortest path lengths on real-world networks using their degree
distribution, or joint degree-degree distribution. Compared to some other
methods, our approach is simpler and yields more accurate results. In order to
obtain the analytical results, we use the analogy between an infection reaching
a node in $n$ discrete time steps (i.e., as in the susceptible-infected
epidemic model) and that node being at a distance $n$ from the source of the
infection.

categories: physics.soc-ph cond-mat.stat-mech cs.DM cs.SI


title:
Resonance fluorescence and laser spectroscopy of three-dimensionally
  confined excitons in monolayer WSe$_2$

abstract:
  Resonant optical excitation of few-level quantum systems enables coherent
quantum control, resonance fluorescence, and direct characterization of
dephasing mechanisms. Experimental demonstrations have been achieved in a
variety of atomic and solid-state systems. An alternative but intriguing
quantum photonic platform is based on single layer transition metal
chalcogenide semiconductors, which exhibit a direct band-gap with optically
addressable exciton valley-pseudospins in a uniquely two-dimensional form. Here
we perform resonance and near-resonance excitation of three-dimensionally
confined excitons in monolayer WSe$_2$ to reveal near ideal single photon
fluorescence with count rates up to 3 MHz and uncover a weakly-fluorescent
exciton state ~ 5 meV blue-shifted from the ground-state exciton. We perform
high-resolution photoluminescence excitation spectroscopy of the localized
excitons, providing important information to unravel the precise nature of the
quantum states. Successful demonstration of resonance fluorescence paves the
way to probe the localized exciton coherence. Moreover, these results yield a
route for investigations of the spin and valley coherence of confined excitons
in two-dimensional semiconductors.


title: Phonon-Dressed Two-Dimensional Carriers on the ZnO Surface

abstract:
  Two-dimensional (2D) metallic states formed on the ZnO(10$\bar{1}$0) surface
by hydrogen adsorption have been investigated using angle-resolved
photoelectron spectroscopy (ARPES). The observed metallic state is
characterized by a peak-dip-hump structure at just below the Fermi level and a
long tail structure extending up to 600 meV in binding energy. The peak and
hump positions are separated by about 70 meV, a value close to the excitation
energy of longitudinal optical (LO) phonons. Spectral functions formulated on
the basis of the 2D electron-phonon coupling well reproduce the ARPES intensity
distribution of the metallic states. This spectral analysis suggests that the
2D electrons accumulated on the ZnO surface couple to the LO phonons and that
this coupling is the origin of the anomalous long tail. Our results indicate
that the 2D electrons at the ZnO surface are described as the electron liquid
model.


title:
Performance, robustness and sensitivity analysis of the nonlinear tuned
  vibration absorber

abstract:
  The nonlinear tuned vibration absorber (NLTVA) is a recently-developed
nonlinear absorber which generalizes Den Hartog's equal peak method to
nonlinear systems. If the purposeful introduction of nonlinearity can enhance
system performance, it can also give rise to adverse dynamical phenomena,
including detached resonance curves and quasiperiodic regimes of motion.
Through the combination of numerical continuation of periodic solutions,
bifurcation detection and tracking, and global analysis, the present study
identifies boundaries in the NLTVA parameter space delimiting safe, unsafe and
unacceptable operations. The sensitivity of these boundaries to uncertainty in
the NLTVA parameters is also investigated.


title:
An Attentive Neural Architecture for Fine-grained Entity Type
  Classification

abstract:
  In this work we propose a novel attention-based neural network model for the
task of fine-grained entity type classification that unlike previously proposed
models recursively composes representations of entity mention contexts. Our
model achieves state-of-the-art performance with 74.94% loose micro F1-score on
the well-established FIGER dataset, a relative improvement of 2.59%. We also
investigate the behavior of the attention mechanism of our model and observe
that it can learn contextual linguistic expressions that indicate the
fine-grained category memberships of an entity.


title: Frequency-Tunable Microwave Field Detection in an Atomic Vapor Cell

abstract:
  We use an atomic vapor cell as a frequency tunable microwave field detector
operating at frequencies from GHz to tens of GHz. We detect microwave magnetic
fields from 2.3 GHz to 26.4 GHz, and measure the amplitude of the sigma+
component of an 18 GHz microwave field. Our proof-of-principle demonstration
represents a four orders of magnitude extension of the frequency tunable range
of atomic magnetometers from their previous dc to several MHz range. When
integrated with a high resolution microwave imaging system, this will allow for
the complete reconstruction of the vector components of a microwave magnetic
field and the relative phase between them. Potential applications include
near-field characterisation of microwave circuitry and devices, and medical
microwave sensing and imaging.

categories: physics.atom-ph physics.ins-det physics.med-ph quant-ph


title:
Thermophoretically induced large-scale deformations around microscopic
  heat centers

abstract:
  Selectively heating a microscopic colloidal particle embedded in a soft
elastic matrix is a situation of high practical relevance. For instance, during
hyperthermic cancer treatment, cell tissue surrounding heated magnetic
colloidal particles is destroyed. Experiments on soft elastic polymeric
matrices suggest a very long-ranged, non-decaying radial component of the
thermophoretically induced displacement fields around the microscopic heat
centers. We theoretically confirm this conjecture using a macroscopic
hydrodynamic two-fluid description. Both, thermophoretic and elastic effects
are included in this theory. Indeed, we find that the elasticity of the
environment can cause the experimentally observed large-scale radial
displacements in the embedding matrix. Additional experiments confirm the
central role of elasticity. Finally, a linearly decaying radial component of
the displacement field in the experiments is attributed to the finite size of
the experimental sample. Similar results are obtained from our theoretical
analysis under modified boundary conditions.


title:
Experimental Study of Dust Acoustic Waves in the Strongly Correlated
  Regime

abstract:
  Low frequency dust acoustic waves (DAW) were excited in a laboratory argon
dusty plasma by modulating the discharge voltage with a low frequency AC
signal. Metallic graphite particles were used as dust grains and a digital FFT
technique was used to obtain dispersion characteristics. The experimental
dispersion relation shows the reduction of phase velocity and a regime where
$\partial \omega/\partial k < 0$. A comparison is made with existing
theoretical model.


title:
Multilingual Part-of-Speech Tagging with Bidirectional Long Short-Term
  Memory Models and Auxiliary Loss

abstract:
  Bidirectional long short-term memory (bi-LSTM) networks have recently proven
successful for various NLP sequence modeling tasks, but little is known about
their reliance to input representations, target languages, data set size, and
label noise. We address these issues and evaluate bi-LSTMs with word,
character, and unicode byte embeddings for POS tagging. We compare bi-LSTMs to
traditional POS taggers across languages and data sizes. We also present a
novel bi-LSTM model, which combines the POS tagging loss function with an
auxiliary loss function that accounts for rare words. The model obtains
state-of-the-art performance across 22 languages, and works especially well for
morphologically complex languages. Our analysis suggests that bi-LSTMs are less
sensitive to training data size and label corruptions (at small noise levels)
than previously assumed.


title:
Distillation of secret key from a class of compound memoryless quantum
  sources

abstract:
  We consider secret-key distillation from tripartite compound
classical-quantum-quantum (cqq) sources with free forward public communication
under strong security criterion. We design protocols which are universally
reliable and secure in this scenario. These are shown to achieve asymptotically
optimal rates as long as a certain regularity condition is fulfilled by the the
set of its generating density matrices. We derive a multi-letter formula which
describes the optimal forward secret-key capacity for all compound cqq sources
being regular in this sense. We also determine the forward secret-key
distillation capacity for situations, where the legitimate sending party has
perfect knowledge of his/her marginal state deriving from the source
statistics. In this case regularity conditions can be dropped. Our results show
that the capacities with and without the mentioned kind of state knowledge are
equal as long as the source is generated by a regular set of density matrices.
We demonstrate that regularity of cqq sources is not only a technical but also
an operational issue. For this reason, we give an example of a source which has
zero secret-key distillation capacity without sender knowledge, while achieving
positive rates is possible if sender marginal knowledge is provided.


title: Ramification theory and formal orbifolds in arbitrary dimension

abstract:
  Formal orbifolds are defined in higher dimension. Their \'etale fundamental
groups are also defined. It is shown that the fundamental groups of formal
orbifolds have certain finiteness property and it is also shown that they can
be used to approximate the \'etale fundamental groups of normal varieties.
Etale site on formal orbifolds are also defined. This framework allows one to
study wild ramification in an organised way. Brylinski-Kato filtration,
Lefschetz theorem for fundamental groups and $l$-adic sheaves in these contexts
are also studied.


title:
A variational approach to the liquid-vapor phase transition for hardcore
  ions in the bulk and in nanopores

abstract:
  We employ a field-theoretical variational approach to study the behavior of
ionic solutions in the grand canonical ensemble. To describe properly the
hardcore interactions between ions, we use a cutoff in Fourier space for the
electrostatic contribution of the grand potential and the Carnahan-Starling
equation of state with a modified chemical potential for the pressure one. We
first calibrate our method by comparing its predictions at room temperature
with Monte Carlo results for excess chemical potential and energy. We then
validate our approach in the bulk phase by describing the classical "ionic
liquid-vapor" phase transition induced by ionic correlations at low
temperature, before applying it to electrolytes at room temperature confined to
nanopores embedded in a low dielectric medium and coupled to an external
reservoir of ions. The ionic concentration in the nanopore is then correctly
described from very low bulk concentrations, where dielectric exclusion shifts
the transition up to room temperature for sufficiently tight nanopores, to high
concentrations where hardcore interactions dominate which, as expected, modify
only slightly this ionic "capillary evaporation".


title:
On Arakawa-Kaneko zeta-functions associated with $GL_2(\mathbb{C})$ and
  their functional relations

abstract:
  We construct a certain class of Arakawa--Kaneko zeta-functions associated
with $GL_2(\mathbb{C})$, which includes the ordinary Arakawa--Kaneko
zeta-function. We also define poly-Bernoulli polynomials associated with
$GL_2(\mathbb{C})$ which appear in their special values of these
zeta-functions. We prove some functional relations for these zeta-functions,
which are regarded as interpolation formulas of various relations among
poly-Bernoulli numbers. Considering their special values, we prove difference
relations and duality relations for poly-Bernoulli polynomials associated with
$GL_2(\mathbb{C})$.


title:
Link Capacity Planning for Fault Tolerant Operation in Hybrid SDN/OSPF
  Networks

abstract:
  Link capacity dimensioning is the periodic task where ISPs have to make
provisions for sudden traffic bursts and network failures to assure
uninterrupted operations. This provision comes in the form of link working
capacities with noticeable amounts of headroom, i.e., spare capacities that are
used in case of congestions or network failures. Distributed routing protocols
like OSPF provide convergence after network failures and have proven their
reliable operation over decades, but require overprovisioning and headroom of
over 50%. However, SDN has recently been proposed to either replace or work
together with OSPF in routing Internet traffic. This paper addresses the
question of how to robustly dimension the link capacities in emerging hybrid
SDN/OSPF networks. We analyze the networks with various implementations of
hybrid SDN/OSPF control planes, and show that our idea of SDN Partitioning
requires less amounts of spare capacity compared to legacy or other hybrid
SDN/OSPF schemes, outperformed only by a full SDN deployment.


title:
The SP theory of intelligence and the representation and processing of
  knowledge in the brain

abstract:
  The "SP theory of intelligence", with its realisation in the "SP computer
model", aims to simplify and integrate observations and concepts across
AI-related fields, with information compression as a unifying theme. This paper
describes how abstract structures and processes in the theory may be realised
in terms of neurons, their interconnections, and the transmission of signals
between neurons. This part of the SP theory -- "SP-neural" -- is a tentative
and partial model for the representation and processing of knowledge in the
brain. In the SP theory (apart from SP-neural), all kinds of knowledge are
represented with "patterns", where a pattern is an array of atomic symbols in
one or two dimensions. In SP-neural, the concept of a "pattern" is realised as
an array of neurons called a "pattern assembly", similar to Hebb's concept of a
"cell assembly" but with important differences. Central to the processing of
information in the SP system is the powerful concept of "multiple alignment",
borrowed and adapted from bioinformatics. Processes such as pattern
recognition, reasoning and problem solving are achieved via the building of
multiple alignments, while unsupervised learning -- significantly different
from the "Hebbian" kinds of learning -- is achieved by creating patterns from
sensory information and also by creating patterns from multiple alignments in
which there is a partial match between one pattern and another. Short-lived
neural structures equivalent to multiple alignments will be created via an
inter-play of excitatory and inhibitory neural signals. The paper discusses
several associated issues, with relevant empirical evidence.


title:
Fabrication of FeSi and Fe3Si compounds by electron beam induced mixing
  of [Fe/Si]2 and [Fe3/Si]2 multilayers grown by focused electron beam induced
  deposition

abstract:
  Fe-Si binary compounds have been fabricated by focused electron beam induced
deposition by the alternating use of iron pentacarbonyl, Fe(CO)5, and
neopentasilane, Si5H12 as precursor gases. The fabrication procedure consisted
in preparing multilayer structures which were treated by low-energy electron
irradiation and annealing to induce atomic species intermixing. In this way we
are able to fabricate FeSi and Fe3Si binary compounds from [Fe=Si]2 and
[Fe3=Si]2 multilayers, as shown by transmission electron microscopy
investigations. This fabrication procedure is useful to obtain nanostructured
binary alloys from precursors which compete for adsorption sites during growth
and, therefore, cannot be used simultaneously.


title:
Scaling theory of thermal rounding phenomena in depinning and related
  transitions

abstract:
  We present a scaling theory for the effect of thermal fluctuations on the
characteristics of the depinning transition, and also in the closely related
directed percolation model. Thermal effects act as a sort of external field
that produces a rounding of the sharp transition occurring at zero temperature.
The theory allows to predict the value of the thermal rounding exponent that
quantifies the rounding effect. It also gives insight into the spatial and
temporal correlations between thermally activated events, which are highly
non-trivial.


title:
Measurements of the charge asymmetry in top-quark pair production in the
  dilepton final state at $\sqrt{s}=8$ TeV with the ATLAS detector

abstract:
  Measurements of the top--antitop quark pair production charge asymmetry in
the dilepton channel, characterized by two high-${p}_{\rm{T}}$ leptons
(electrons or muons), are presented using data corresponding to an integrated
luminosity of $20.3$ $\textrm{fb}^{-1}$ from $pp$ collisions at a
center-of-mass energy of $\sqrt{s} = 8$ TeV collected with the ATLAS detector
at the Large Hadron Collider at CERN. Inclusive and differential measurements
as a function of the invariant mass, transverse momentum, and longitudinal
boost of the $t\bar{t}$ system are performed both in the full phase space and
in a fiducial phase space closely matching the detector acceptance. Two
observables are studied: $A^{\ell\ell}_{\textrm{C}}$ based on the selected
leptons and $A^{t\bar{t}}_{\textrm{C}}$ based on the reconstructed $t\bar{t}$
final state. The inclusive asymmetries are measured in the full phase space to
be $A^{\ell\ell}_{\textrm{C}} = 0.008 \pm 0.006$ and $A^{t\bar{t}}_{\textrm{C}}
= 0.021 \pm 0.016$, which are in agreement with the Standard Model predictions
of $A^{\ell\ell}_{\textrm{C}} = 0.0064 \pm 0.0003 $ and
$A^{t\bar{t}}_{\textrm{C}} = 0.0111 \pm 0.0004$.


title:
On the viscous Cahn-Hilliard equation with singular potential and
  inertial term

abstract:
  We consider a relaxation of the viscous Cahn-Hilliard equation induced by the
second-order inertial term~$u_{tt}$. The equation also contains a semilinear
term $f(u)$ of "singular" type. Namely, the function $f$ is defined only on a
bounded interval of ${\mathbb R}$ corresponding to the physically admissible
values of the unknown $u$, and diverges as $u$ approaches the extrema of that
interval. In view of its interaction with the inertial term $u_{tt}$, the term
$f(u)$ is difficult to be treated mathematically. Based on an approach
originally devised for the strongly damped wave equation, we propose a suitable
concept of weak solution based on duality methods and prove an existence
result.


title: Discretizing the Heston Model: An Analysis of the Weak Convergence Rate

abstract:
  In this manuscript we analyze the weak convergence rate of a discretization
scheme for the Heston model. Under mild assumptions on the smoothness of the
payoff and on the Feller index of the volatility process, respectively, we
establish a weak convergence rate of order one. Moreover, under almost minimal
assumptions we obtain weak convergence without a rate. These results are
accompanied by several numerical examples. Our error analysis relies on a
classical technique from Talay & Tubaro, a recent regularity estimate for the
Heston PDE by Feehan & Pop and Malliavin calculus.


title: Insertion-tolerance and repetitiveness of random graphs

abstract:
  Bond percolation on Cayley graphs provides examples of random graphs. Other
examples arise from the dynamical study of proper repetitive subgraphs of
Cayley graphs. In this paper we demonstrate that these two families have
mutually singular laws as a corollary of a general lemma about countable Borel
equivalence relations on first countable Hausdorff spaces.


title: Using semidirect product of (semi)groups in public key cryptography

abstract:
  In this survey, we describe a general key exchange protocol based on
semidirect product of (semi)groups (more specifically, on extensions of
(semi)groups by automorphisms), and then focus on practical instances of this
general idea. This protocol can be based on any group or semigroup, in
particular on any non-commutative group. One of its special cases is the
standard Diffie-Hellman protocol, which is based on a cyclic group. However,
when this protocol is used with a non-commutative (semi)group, it acquires
several useful features that make it compare favorably to the Diffie-Hellman
protocol. The focus then shifts to selecting an optimal platform (semi)group,
in terms of security and efficiency. We show, in particular, that one can get a
variety of new security assumptions by varying an automorphism used for a
(semi)group extension.


title:
Easy to Win, Hard to Master: Optimal Strategies in Parity Games with
  Costs

abstract:
  The winning condition of a parity game with costs requires an arbitrary, but
fixed bound on the cost incurred between occurrences of odd colors and the next
occurrence of a larger even one. Such games quantitatively extend parity games
while retaining most of their attractive properties, i.e, determining the
winner is in NP and co-NP and one player has positional winning strategies.
  We show that the characteristics of parity games with costs are vastly
different when asking for strategies realizing the minimal such bound: The
solution problem becomes PSPACE-complete and exponential memory is both
necessary in general and always sufficient. Thus, solving and playing parity
games with costs optimally is harder than just winning them. Moreover, we show
that the tradeoff between the memory size and the realized bound is gradual in
general. All these results hold true for both a unary and binary encoding of
costs.
  Moreover, we investigate Streett games with costs. Here, playing optimally is
as hard as winning, both in terms of complexity and memory.


title: Jarzynski's theorem for lattice gauge theory

abstract:
  Jarzynski's theorem is a well-known equality in statistical mechanics, which
relates fluctuations in the work performed during a non-equilibrium
transformation of a system, to the free-energy difference between two
equilibrium ensembles. In this article, we apply Jarzynski's theorem in lattice
gauge theory, for two examples of challenging computational problems, namely
the calculation of interface free energies and the determination of the
equation of state. We conclude with a discussion of further applications of
interest in QCD and in other strongly coupled gauge theories, in particular for
the Schroedinger functional and for simulations at finite density using
reweighting techniques.


title:
Global integration of the Schr\"odinger equation within the wave
  operator formalism: The role of the effective Hamiltonian in multidimensional
  active spaces

abstract:
  A global solution of the Schr\"odinger equation, obtained recently within the
wave operator formalism for explicitly time-dependent Hamiltonians [J. Phys. A:
Math. Theor. 48, 225205 (2015)], is generalized to take into account the case
of multidimensional active spaces. An iterative algorithm is derived to obtain
the Fourier series of the evolution operator issuing from a given
multidimensional active subspace and then the effective Hamiltonian
corresponding to the model space is computed and analysed as a measure of the
cyclic character of the dynamics. Studies of the laser controlled dynamics of
diatomic models clearly show that a multidimensional active space is required
if the wavefunction escapes too far from the initial subspace. A suitable
choice of the multidimensional active space, including the initial and target
states, increases the cyclic character and avoids divergences occuring when
one-dimensional active spaces are used. The method is also proven to be
efficient in describing dissipative processes such as photodissociation.


title:
Transport through a quantum spin Hall antidot as a spectroscopic probe
  of spin textures

abstract:
  We investigate electron transport through an antidot embedded in a narrow
strip of two-dimensional topological insulator. We focus on the most generic
and experimentally relevant case with broken axial spin symmetry.
Spin-non-conservation allows additional scattering processes which change the
transport properties profoundly. We start from an analytical model for
noninteracting transport, which we also compare with a numerical tight-binding
simulation. We then extend this model by including Coulomb repulsion on the
antidot, and we study the transport in the Coulomb-blockade limit. We
investigate sequential tunneling and cotunneling regimes, and we find that the
current-voltage characteristic allows a spectroscopic measurement of the
edge-state spin textures.


title: Gravity: a gauge theory perspective

abstract:
  The evolution of a generally covariant theory is under-determined. One
hundred years ago such dynamics had never before been considered; its
ramifications were perplexing, its future important role for all the
fundamental interactions under the name gauge principle could not be foreseen.
We recount some history regarding Einstein, Hilbert, Klein and Noether and the
novel features of gravitational energy that led to Noether's two theorems.
Under-determined evolution is best revealed in the Hamiltonian formulation. We
developed a covariant Hamiltonian formulation. The Hamiltonian boundary term
gives covariant expressions for the quasi-local energy, momentum and angular
momentum. Gravity can be considered as a gauge theory of the local Poincar\'e
group. The dynamical potentials of the Poincar\'e gauge theory of gravity are
the frame and the connection. The spacetime geometry has in general both
curvature and torsion. Torsion naturally couples to spin; it could have a
significant magnitude and yet not be noticed, except on a cosmological scale
where it could have significant effects.


title:
Covariant Hamiltonian boundary term: Reference and quasi-local
  quantities

abstract:
  The Hamiltonian for dynamic geometry generates the evolution of a spatial
region along a vector field. It includes a boundary term which determines both
the value of the Hamiltonian and the boundary conditions. The value gives the
quasi-local quantities: energy-momentum, angular-momentum and center-of-mass.
The boundary term depends not only on the dynamical variables but also on their
reference values; the latter determine the ground state (having vanishing
quasi-local quantities). For our preferred boundary term for Einstein's GR we
propose 4D isometric matching and extremizing the energy to determine the
reference metric and connection values.


title: Local stability and Hopf bifurcation analysis for Compound TCP

abstract:
  We conduct a local stability and Hopf bifurcation analysis for Compound TCP,
with small Drop-tail buffers, in three topologies. The first topology consists
of two sets of TCP flows having different round trip times, and feeding into a
core router. The second topology corresponds to two queues in tandem, and
consists of two distinct sets of TCP flows, regulated by a single edge router
and feeding into a core router. The third topology comprises of two distinct
sets of TCP flows, regulated by two separate edge routers, and feeding into a
common core router. For each of these cases, we conduct a detailed local
stability analysis and obtain conditions on the network and protocol parameters
to ensure stability. If these conditions get marginally violated, our analysis
shows that the underlying systems would lose local stability via a Hopf
bifurcation. After exhibiting a Hopf, a key concern is to determine the
asymptotic orbital stability of the bifurcating limit cycles. We present a
detailed analytical framework to address the stability of the limit cycles, and
the type of the Hopf bifurcation by invoking Poincare normal forms and the
center manifold theory. We conduct packet-level simulations to highlight the
existence and stability of the limit cycles in the queue size dynamics.