title:
An Approximate Nash Equilibrium for Pure Jump Markov Games of
  Mean-field-type on Continuous State Space

abstract:
  We investigate mean-field games from the point of view of a large number of
indistinguishable players which eventually converges to infinity. The players
are weakly coupled via their empirical measure. The dynamics of the states of
the individual players is governed by a non-autonomous pure jump type semi
group in a Euclidean space, which is not necessarily smoothing. Investigations
are conducted in the framework of non-linear Markov processes. We show that the
individual optimal strategy results from a consistent coupling of an optimal
control problem with a forward non-autonomous dynamics. In the limit as the
number $N$ of players goes to infinity this leads to a jump-type analog of the
well-known non-linear McKean-Vlasov dynamics. The case where one player has an
individual preference different from the ones of the remaining players is also
covered. The two results combined reveal an epsilon-Nash Equilibrium for the
$N$-player games.


title:
The Erd\H{o}s-Rothschild problem on edge-colourings with forbidden
  monochromatic cliques

abstract:
  Let $\mathbf{k} := (k_1,\dots,k_s)$ be a sequence of natural numbers. For a
graph $G$, let $F(G;\mathbf{k})$ denote the number of colourings of the edges
of $G$ with colours $1,\dots,s$ such that, for every $c \in \{1,\dots,s\}$, the
edges of colour $c$ contain no clique of order $k_c$. Write $F(n;\mathbf{k})$
to denote the maximum of $F(G;\mathbf{k})$ over all graphs $G$ on $n$ vertices.
This problem was first considered by Erd\H{o}s and Rothschild in 1974, but it
has been solved only for a very small number of non-trivial cases.
  We prove that, for every $\mathbf{k}$ and $n$, there is a complete
multipartite graph $G$ on $n$ vertices with $F(G;\mathbf{k}) =
F(n;\mathbf{k})$. Also, for every $\mathbf{k}$ we construct a finite
optimisation problem whose maximum is equal to the limit of $\log_2
F(n;\mathbf{k})/{n\choose 2}$ as $n$ tends to infinity. Our final result is a
stability theorem for complete multipartite graphs $G$, describing the
asymptotic structure of such $G$ with $F(G;\mathbf{k}) = F(n;\mathbf{k}) \cdot
2^{o(n^2)}$ in terms of solutions to the optimisation problem.


title:
The semi-digital hadronic calorimeter (SDHCAL) for future leptonic
  colliders

abstract:
  The first technological SDHCAL prototype having been successfully tested, a
new phase of R&D, to validate completely the SDHCAL option for the
International Linear Detector (ILD) project of the International Linear
Collider (ILC), has started with the conception and the realisation of a new
prototype. The new one is intended to host few but large active layers of the
future SDHCAL. The new active layers, made of Glass Resistive Plate Chambers
(GRPC) with sizes larger than 2m^2 will be equipped with a new version of the
electronic readout, fulfilling the requirements of the future ILD detector. The
new GRPC are conceived to improve the homogeneity with a new gas distribution
scheme. Finally the mechanical structure will be achieved using the electron
beam welding technique. The progress realised will be presented and future
steps will be discussed.


title: Ruled surfaces of finite type in 3-dimensional Heisenberg group

abstract:
  In this paper, on the first, we prove $\Delta r=2H$ where $\Delta $ is the
Laplacian operator, $r=\left( r_{1},r_{2},r_{3}\right) $ the position vector
field and $H$ is the mean curvature vector field of a surface $\mathcal{S}$ in
the 3-dimensional Heisenberg group $H_{3}.$ In the second, we classify the
ruled surfaces by straight geodesic lines, which are of finite type in $H_{3}.$
The straight geodesic lines belong to $\ker \omega ,$ where $\omega $ is the
Darboux form.


title: Ad-Blocking and Counter Blocking: A Slice of the Arms Race

abstract:
  Adblocking tools like Adblock Plus continue to rise in popularity,
potentially threatening the dynamics of advertising revenue streams. In
response, a number of publishers have ramped up efforts to develop and deploy
mechanisms for detecting and/or counter-blocking adblockers (which we refer to
as anti-adblockers), effectively escalating the online advertising arms race.
In this paper, we develop a scalable approach for identifying third-party
services shared across multiple web-sites and use it to provide a first
characterization of anti-adblocking across the Alexa Top-5K websites. We map
websites that perform anti-adblocking as well as the entities that provide
anti-adblocking scripts. We study the modus operandi of these scripts and their
impact on popular adblockers. We find that at least 6.7% of websites in the
Alexa Top-5K use anti-adblocking scripts, acquired from 12 distinct entities --
some of which have a direct interest in nourishing the online advertising
industry.


title:
Exploratory Chandra observation of the ultraluminous quasar SDSS
  J010013.02+280225.8 at redshift 6.30

abstract:
  We report exploratory \chandra\ observation of the ultraluminous quasar SDSS
J010013.02+280225.8 at redshift 6.30. The quasar is clearly detected by
\chandra\ with a possible component of extended emission. The rest-frame 2-10
keV luminosity is 9.0$^{+9.1}_{-4.5}$ $\times$ 10$^{45}$ erg s$^{-1}$ with
inferred photon index of $\Gamma$ = 3.03$^{+0.78}_{-0.70}$. This quasar is
X-ray bright, with inferred X-ray-to-optical flux ratio \aox\
$=-1.22^{+0.07}_{-0.05}$, higher than the values found in other quasars of
comparable ultraviolet luminosity. The properties inferred from this
exploratory observation indicate that this ultraluminous quasar might be
growing with super-Eddington accretion and probably viewed with small
inclination angle. Deep X-ray observation will help to probe the plausible
extended emission and better constraint the spectral features for this
ultraluminous quasar.


title:
Semantics of Higher-Order Quantum Computation via Geometry of
  Interaction

abstract:
  While much of the current study on quantum computation employs low-level
formalisms such as quantum circuits, several high-level languages/calculi have
been recently proposed aiming at structured quantum programming. The current
work contributes to the semantical study of such languages by providing
interaction-based semantics of a functional quantum programming language; the
latter is, much like Selinger and Valiron's, based on linear lambda calculus
and equipped with features like the ! modality and recursion. The proposed
denotational model is the first one that supports the full features of a
quantum functional programming language; we prove adequacy of our semantics.
The construction of our model is by a series of existing techniques taken from
the semantics of classical computation as well as from process theory. The most
notable among them is Girard's Geometry of Interaction (GoI), categorically
formulated by Abramsky, Haghverdi and Scott. The mathematical genericity of
these techniques---largely due to their categorical formulation---is exploited
for our move from classical to quantum.


title: Fermi-Pasta-Ulam recurrence and modulation instability

abstract:
  We give a qualitative explanation of the analog of the Fermi-Pasta-Ulam (FPU)
recurrence in a one-dimensional focusing nonlinear Schrodinger equation (NLSE).
That recurrence can be considered as a result of the nonlinear development of
modulation instability. All known exact localized solitons-type solutions
describing propagation on the background of the modulationally unstable
condensate show the recurrence to the condensate state after its interaction
with solitons. The condensate state locally recovers its original form with the
same amplitude but a different phase after soliton leave its initial region.
This is the analog of the FPU recurrence for the NLSE. Based on the
integrability of the NLSE, we demonstrate that the FPU recurrence takes place
not only for condensate but for more general solution in the form of the
cnoidal wave. This solution is periodic in space and can be represented as a
solitonic lattice. That lattice reduces to isolated soliton solution in the
limit of large distance between solitons. The lattice transforms into the
condensate in the opposite limit of dense soliton packing. The cnoidal wave is
also modulationally unstable due to soliton overlapping. This instability at
the linear stage does not provide the cnoidal wave recurrence. The recurrence
happens at the nonlinear stage of the modulation instability. From the
practical point of view the latter property is very important, especially for
the fiber communication systems which use soliton as an information carrier.

categories: nlin.SI cond-mat.stat-mech physics.optics physics.plasm-ph


title:
Search for the Lepton Flavour Violating Decay $\mu^{+} \to e^+ \gamma$
  with the Full Dataset of the MEG Experiment

abstract:
  The final results of the search for the lepton flavour violating decay
$\mu^{+} \rightarrow {\rm e^{+}} \gamma$ based on the full dataset collected by
the MEG experiment at the Paul Scherrer Institut in the period 2009--2013 and
totalling $7.5\times 10^{14}$ stopped muons on target are presented. No
significant excess of events is observed in the dataset with respect to the
expected background and a new upper limit on the branching ratio of this decay
of $BR( \mu^{+} \rightarrow {\rm e^{+}} \gamma ) < 4.2 \times 10^{-13}$ (90\%\
confidence level) is established, which represents the most stringent limit on
the existence of this decay to date.


title: Efficient Algorithms for Mixed Creative Telescoping

abstract:
  Creative telescoping is a powerful computer algebra paradigm -initiated by
Doron Zeilberger in the 90's- for dealing with definite integrals and sums with
parameters. We address the mixed continuous-discrete case, and focus on the
integration of bivariate hypergeometric-hyperexponential terms. We design a new
creative telescoping algorithm operating on this class of inputs, based on a
Hermite-like reduction procedure. The new algorithm has two nice features: it
is efficient and it delivers, for a suitable representation of the input, a
minimal-order telescoper. Its analysis reveals tight bounds on the sizes of the
telescoper it produces.


title: Parametric down-conversion with nonideal and random quasi-phase-matching

abstract:
  Quasi-phase-matching (QPM) has enriched the capacity of parametric
down-conversion (PDC) in generating biphotons for many fundamental tests and
advanced applications. However, it is not clear how the nonidealities and
randomness in the QPM grating of a parametric down-converter may affect the
quantum properties of the biphotons. This paper intends to provide insights
into the interplay between PDC and nonideal or random QPM structures. Using a
periodically poled nonlinear crystal with short periodicity, we conduct
experimental and theoretical studies of PDC subject to nonideal duty cycle and
random errors in domain lengths. We report the observation of biphotons
emerging through noncritical birefringent-phase-matching, which is impossible
to occur in PDC with an ideal QPM grating, and a biphoton spectrum determined
by the details of nonidealities and randomness. We also observed QPM biphotons
with a diminished strength. These features are both confirmed by our theory.
Our work provides new perspectives for biphoton engineering with QPM.


title:
Path decomposition of a spectrally negative L\'evy process, and local
  time of a diffusion in this environment

abstract:
  We study the convergence in distribution of the supremum of the local time
and of the favorite site for a transient diffusion in a spectrally negative
L\'evy potential. To do so, we study the h-valleys of a spectrally negative
L\'evy process, and we prove in partiular that the renormalized sequence of the
h-minima converges to the jumping times sequence of a standard Poisson process.


title: Tuning the receding contact angle on hydrogels by addition of particles

abstract:
  Control of the swelling, chemical functionalization, and adhesivity of
hydrogels are finding new applications in a wide range of material systems. We
investigate experimentally the effect of adsorbed particles on hydrogels on the
depinning of contact lines. In our experiments, a water drop containing
polystyrene microspheres is deposited on a swelling hydrogel, which leads to
the drop absorption and particle deposition. Two regimes are observed: a
decreasing drop height with a pinned contact line followed by a receding
contact line. We show that increasing the particles concentration increases the
duration of the first regime and significantly decreases the total absorption
time. The adsorbed particles increase the pinning force at the contact line.
Finally, we develop a method to measure the receding contact angle with the
consideration of the hydrogel swelling.


title:
Interfacial structure and electronic properties of AFM/FM magnetic
  multilayer revealed by Scanning Tunneling Microscope

abstract:
  Mixing of atoms at the interface was studied for Mn/Fe magnetic
hetero-epitaxial layers on Cu(001) by scanning tunneling
microscopy/spectroscopy. The formation of a surface alloy was observed when the
Mn layer was thinner than 3 atomic layers. From the fourth layer, Fe
segregation is suppressed, and a pure Mn surface appears. Accordingly,
spectroscopic measurements revealed the electronic difference between the
surface alloy and Mn layers. The surface electronic structure of the fourth Mn
layer is slightly different from that of the fifth layers, which is attributed
to the hybridization of the fourth layer with the underneath Fe-Mn alloy.


title:
Word2Vec is a special case of Kernel Correspondence Analysis and Kernels
  for Natural Language Processing

abstract:
  We show that correspondence analysis (CA) is equivalent to defining a Gini
index with appropriately scaled one-hot encoding. Using this relation, we
introduce a nonlinear kernel extension to CA. This extended CA gives a known
analysis for natural language via specialized kernels that use an appropriate
contingency table. We propose a semi-supervised CA, which is a special case of
the kernel extension to CA. Because CA requires excessive memory if applied to
numerous categories, CA has not been used for natural language processing. We
address this problem by introducing delayed evaluation to randomized singular
value decomposition. The memory-efficient CA is then applied to a word-vector
representation task. We propose a tail-cut kernel, which is an extension to the
skip-gram within the kernel extension to CA. Our tail-cut kernel outperforms
existing word-vector representation methods.


title: An empirical model to form and evolve galaxies in dark matter halos

abstract:
  Based on the star formation histories (SFH) of galaxies in halos of different
masses, we develop an empirical model to grow galaxies in dark mattet halos.
This model has very few ingredients, any of which can be associated to
observational data and thus be efficiently assessed. By applying this model to
a very high resolution cosmological $N$-body simulation, we predict a number of
galaxy properties that are a very good match to relevant observational data.
Namely, for both centrals and satellites, the galaxy stellar mass function
(SMF) up to redshift $z\simeq4$ and the conditional stellar mass functions
(CSMF) in the local universe are in good agreement with observations. In
addition, the 2-point correlation is well predicted in the different stellar
mass ranges explored by our model. Furthermore, after applying stellar
population synthesis models to our stellar composition as a function of
redshift, we find that the luminosity functions in $^{0.1}u$, $^{0.1}g$,
$^{0.1}r$, $^{0.1}i$ and $^{0.1}z$ bands agree quite well with the SDSS
observational results down to an absolute magnitude at about -17.0. The SDSS
conditional luminosity functions (CLF) itself is predicted well. Finally, the
cold gas is derived from the star formation rate (SFR) to predict the HI gas
mass within each mock galaxy. We find a remarkably good match to observed
HI-to-stellar mass ratios. These features ensure that such galaxy/gas catalogs
can be used to generate reliable mock redshift surveys.


title: Random motion on finite rings, I: commutative rings

abstract:
  We consider irreversible Markov chains on finite commutative rings randomly
generated using both addition and multiplication. We restrict ourselves to the
case where the addition is uniformly random and multiplication is arbitrary.
  We first prove formulas for eigenvalues and multiplicities of the transition
matrices of these chains using the character theory of finite abelian groups.
The examples of principal ideal rings (such as $\mathbb{Z}_{n}$) and finite
chain rings (such as $\mathbb{Z}_{p^k}$) are particularly illuminating and are
treated separately. We then prove a recursive formula for the stationary
probabilities for any ring, and use it to prove explicit formulas for the
probabilities for finite chain rings when multiplication is also uniformly
random. Finally, we prove constant mixing time for our chains using coupling.


title: Arithmetically-free group-gradings of Lie algebras: II

abstract:
  We study group-graded Lie algebras L with finite support X. We show that L is
nilpotent of |X|-bounded class if X is arithmetically-free. Conversely: we show
that Y supports the grading of a non-nilpotent Lie algebra if Y is not
arithmetically-free.


title: YETI observations of the young transiting planet candidate CVSO 30 b

abstract:
  CVSO 30 is a unique young low-mass system, because, for the first time, a
close-in transiting and a wide directly imaged planet candidates are found
around a common host star. The inner companion, CVSO 30 b, is the first
possible young transiting planet orbiting a previously known weak-lined T-Tauri
star. With five telescopes of the 'Young Exoplanet Transit Initiative' (YETI)
located in Asia, Europe and South America we monitored CVSO 30 over three years
in a total of 144 nights and detected 33 fading events. In two more seasons we
carried out follow-up observations with three telescopes. We can confirm that
there is a change in the shape of the fading event between different
observations and that the fading event even disappears and reappears. A total
of 38 fading event light curves were simultaneously modelled. We derived the
planetary, stellar, and geometrical properties of the system and found them
slightly smaller but in agreement with the values from the discovery paper. The
period of the fading event was found to be 1.36 s shorter and 100 times more
precise than the previous published value. If CVSO 30 b would be a giant planet
on a precessing orbit, which we cannot confirm, yet, the precession period may
be shorter than previously thought. But if confirmed as a planet it would be
the youngest transiting planet ever detected and will provide important
constraints on planet formation and migration time-scales.


title: Wireless Quantum Key Distribution in Indoor Environments

abstract:
  We propose and study the feasibility of wireless quantum key distribution
(QKD) in indoor environments. Such systems are essential in providing wireless
access to the developing quantum communications networks. We find a practical
regime of operation, where, in the presence of external light sources and loss,
secret keys can be exchanged. Our findings identify the trade-off between the
acceptable amount of background light and the receiver field of view, where the
latter affects the ease of access to the QKD system. In particular, we show
that, using a proper setting, we can provide mobility for the QKD users without
imposing stringent conditions on beam steering.


title:
Volatile carbon locking and release in protoplanetary disks. A study of
  TW Hya and HD 100546

abstract:
  The composition of planetary solids and gases is largely rooted in the
processing of volatile elements in protoplanetary disks. To shed light on the
key processes, we carry out a comparative analysis of the gas-phase carbon
abundance in two systems with a similar age and disk mass, but different
central stars: HD 100546 and TW Hya. We combine our recent detections of
C$^{0}$ in these disks with observations of other carbon reservoirs (CO,
C$^{+}$, C$_{2}$H) and gas mass and warm gas tracers (HD, O$^{0}$), as well as
spatially resolved ALMA observations and the spectral energy distribution. The
disks are modelled with the DALI 2D physical-chemical code. Stellar abundances
for HD 100546 are derived from archival spectra. Upper limits on HD emission
from HD 100546 place an upper limit on the total disk mass of
$\leq0.1\,M_{\odot}$. The gas-phase carbon abundance in the atmosphere of this
warm Herbig disk is at most moderately depleted compared to the interstellar
medium, with [C]/[H]$_{\rm gas}=(0.1-1.5)\times 10^{-4}$. HD 100546 itself is a
$\lambda\,$Bo\"{o}tis star, with solar abundances of C and O but a strong
depletion of rock-forming elements. In the gas of the T Tauri disk TW Hya, both
C and O are strongly underabundant, with [C]/[H]$_{\rm gas}=(0.2-5.0)\times
10^{-6}$ and C/O${>}1$. We discuss evidence that the gas-phase C and O
abundances are high in the warm inner regions of both disks. Our analytical
model, including vertical mixing and a grain size distribution, reproduces the
observed [C]/[H]$_{\rm gas}$ in the outer disk of TW Hya and allows to make
predictions for other systems.


title: A generalized Neyman-Pearson lemma for sublinear expectations

abstract:
  In this paper, the Neyman-Pearson lemma for general sublinear expectations is
studied. We weaken the assumptions for sublinear expectations in [1] and give a
completely new method to study this problem. Applying Mazur-Orlicz Theorem and
the decomposition theorem of finitely additive set functions, we prove that the
optimal test still has the reminiscent form as in the classical Neyman-Pearson
lemma. Finally, for the special sublinear expectation which can be represented
by a family of probability measures, we give a sufficient condition for the
existence of the optimal test and show the form of the optimal test selected in
L_{c}^1-space which is introduced by Peng [10] in his nonlinear-expectation
framework.


title: Stability of stratified two-phase flows in inclined channels

abstract:
  Linear stability of stratified gas-liquid and liquid-liquid plane-parallel
flows in inclined channels is studied with respect to all wavenumber
perturbations. The main objective is to predict parameter regions in which
stable stratified configuration in inclined channels exists. Up to three
distinct base states with different holdups exist in inclined flows, so that
the stability analysis has to be carried out for each branch separately.
Special attention is paid to the multiple solution regions to reveal the
feasibility of non-unique stable stratified configurations in inclined
channels. The stability boundaries of each branch of steady state solutions are
presented on the flow pattern map and are accompanied by critical wavenumbers
and spatial profiles of the most unstable perturbations. Instabilities of
different nature are visualized by streamlines of the neutrally stable
perturbed flows, consisting of the critical perturbation superimposed on the
base flow. The present analysis confirms the existence of two stable stratified
flow configurations in a region of low flow rates in countercurrent
liquid-liquid flows. These configurations become unstable with respect to shear
mode of instability. It was revealed that in slightly upward inclined flows the
lower and middle solutions for the holdup are stable in a part of the triple
solution region, while the upper solution is always unstable. In the case of
downward flows, in the triple solution region, none of the solutions are stable
with respect to short-wave perturbations. These flows are stable only in the
single solution region at low flow rates of the heavy phase, where long-wave
perturbations are the most unstable ones.


title: Worst-case shape optimization for the Dirichlet energy

abstract:
  We consider the optimization problem for a shape cost functional
$F(\Omega,f)$ which depends on a domain $\Omega$ varying in a suitable
admissible class and on a "right-hand side" $f$. More precisely, the cost
functional $F$ is given by an integral which involves the solution $u$ of an
elliptic PDE in $\Omega$ with right-hand side $f$; the boundary conditions
considered are of the Dirichlet type. When the function $f$ is only known up to
some degree of uncertainty, our goal is to obtain the existence of an optimal
shape in the worst possible situation. Some numerical simulations are provided,
showing the difference in the optimal shape between the case when $f$ is
perfectly known and the case when only the worst situation is optimized.


title: A tabu search method for the optimisation of fluid power circuits

abstract:
  This paper describes the development of an efficient algorithm for the
optimization of fluid power circuits. The algorithm is based around the
concepts of Tabu search, where different timescale memory cycles are used as a
metaheuristic to guide a hill climbing search method out of local optima and
locate the globally optimum solution. Results are presented which illustrate
the effectiveness of the method on mathematical test functions. In addition to
these test functions, some results are presented for real problems in hydraulic
circuit design by linking the method to the Bathfp dynamic simulation software.
In one such example the solutions obtained are compared to those found using
simple steady state calculations.


title: Direct Detection of Exothermic Dark Matter with Light Mediator

abstract:
  We study the dark matter (DM) direct detection for the models with the
effects of the isospin-violating couplings, exothermic scatterings, and/or the
lightness of the mediator, proposed to relax the tension between the CDMS-Si
signals and null experiments. In the light of the new updates of the LUX and
CDMSlite data, we find that many of the previous proposals are now ruled out,
including the Ge-phobic exothermic DM model and the Xe-phobic DM one with a
light mediator. We also examine the exothermic DM models with a light mediator
but without the isospin violation, and we are unable to identify any available
parameter space that could simultaneously satisfy all the experiments. The only
models that can partially relax the inconsistencies are the Xe-phobic
exothermic DM models with or without a light mediator. But even in this case, a
large portion of the CDMS-Si regions of interest has been constrained by the
LUX and SuperCDMS data.


title: Plasma-enhanced chemical vapor deposition of amorphous Si on graphene

abstract:
  Plasma-enhanced chemical vapor deposition of thin a-Si:H layers on
transferred large area graphene is investigated. Radio frequency (RF, 13.56
MHz) and very high frequency (VHF, 140 MHz) plasma processes are compared. Both
methods provide conformal coating of graphene with Si layers as thin as 20 nm
without any additional seed layer. The RF plasma process results in
amorphization of the graphene layer. In contrast, the VHF process keeps the
high crystalline quality of the graphene layer almost intact. Correlation
analysis of Raman 2D and G band positions indicates that Si deposition induces
reduction of the initial doping in graphene and an increase of compressive
strain. Upon rapid thermal annealing the amorphous Si layer undergoes
dehydrogenation and transformation into a polycrystalline film whereby a high
crystalline quality of graphene is preserved.


title: Wrong-Way Risk Models: A Comparison of Analytical Exposures

abstract:
  In this paper, we compare static and dynamic (reduced form) approaches for
modeling wrong-way risk in the context of CVA. Although all these approaches
potentially suffer from arbitrage problems, they are popular (respectively) in
industry and academia, mainly due to analytical tractability reasons. We
complete the stochastic intensity models with another dynamic approach,
consisting in the straight modeling of the survival (Az\'ema supermartingale)
process using the $\Phi$-martingale. Just like the other approaches, this
method allows for automatic calibration to a given default probability curve.
We derive analytically the positive exposures $V^+_t$ "conditional upon
default" associated to prototypical market price processes of FRA and IRS in
all cases. We further discuss the link between the "default" condition and
change-of-measure techniques. The expectation of $V^+_t$ conditional upon
$\tau=t$ is equal to the unconditional expectation of $V^+_t\zeta_t$. The
process $\zeta$ is explicitly derived in the dynamic approaches: it is proven
to be positive and to have unit expectation. Unfortunately however, it fails to
be a martingale, so that Girsanov machinery cannot be used. Nevertheless, the
expectation of $V^+_t\zeta_t$ can be computed explicitly, leading to analytical
expected positive exposure profiles in the considered examples.


title:
Recurrent Neural Network for Text Classification with Multi-Task
  Learning

abstract:
  Neural network based methods have obtained great progress on a variety of
natural language processing tasks. However, in most previous works, the models
are learned based on single-task supervised objectives, which often suffer from
insufficient training data. In this paper, we use the multi-task learning
framework to jointly learn across multiple related tasks. Based on recurrent
neural network, we propose three different mechanisms of sharing information to
model text with task-specific and shared layers. The entire network is trained
jointly on all these tasks. Experiments on four benchmark text classification
tasks show that our proposed models can improve the performance of a task with
the help of other related tasks.


title: Enumeration of Enumeration Algorithms

abstract:
  In this paper, we enumerate enumeration problems and algorithms. This survey
is under construction. If you know some results not in this survey or there is
anything wrong, please let me know.


title: Shape Coexistence in 78 Ni and the new Island of Inversion

abstract:
  Large Scale Shell Model calculations (SM-CI) predict that the region of
deformation which comprises the heaviest Chromium and Iron isotopes at and
beyond N=40 will merge with a new one at N=50 in an astonishing parallel to the
N=20 and N=28 case in the Neon and Magnesium isotopes. We propose a valence
space including the full pf-shell for the protons and the full sdg shell for
the neutrons; which represents a comeback of the the harmonic oscillator shells
in the very neutron rich regime. The onset of deformation is understood in the
framework of the algebraic SU3-like structures linked to quadrupole dominance.
Our calculations preserve the doubly magic nature of the ground state of 78 Ni,
which, however, exhibits a well deformed prolate band at low excitation energy,
providing a striking example of shape coexistence far from stability.


title:
Abstract Program Slicing: an Abstract Interpretation-based approach to
  Program Slicing

abstract:
  In the present paper we formally define the notion of abstract program
slicing, a general form of program slicing where properties of data are
considered instead of their exact value. This approach is applied to a language
with numeric and reference values, and relies on the notion of abstract
dependencies between program components (statements).
  The different forms of (backward) abstract slicing are added to an existing
formal framework where traditional, non-abstract forms of slicing could be
compared. The extended framework allows us to appreciate that abstract slicing
is a generalization of traditional slicing, since traditional slicing (dealing
with syntactic dependencies) is generalized by (semantic) non-abstract forms of
slicing, which are actually equivalent to an abstract form where the identity
abstraction is performed on data.
  Sound algorithms for computing abstract dependencies and a systematic
characterization of program slices are provided, which rely on the notion of
agreement between program states.


title: Quantum Integrable Systems from Conformal Blocks

abstract:
  In this note, we extend the striking connections between quantum integrable
systems and conformal blocks recently found in http://arxiv.org/abs/1602.01858
in several directions. First, we explicitly demonstrate that the action of
quartic conformal Casimir operator on general d-dimensional scalar conformal
blocks, can be expressed in terms of certain combinations of commuting
integrals of motions of the two particle hyperbolic BC2 Calogero-Sutherland
system. The permutation and reflection properties of the underlying Dunkl
operators play crucial roles in establishing such a connection. Next, we show
that the scalar superconformal blocks in SCFTs with four and eight supercharges
and suitable chirality constraints can also be identified with the
eigenfunctions of the same Calogero-Sutherland system, this demonstrates the
universality of such a connection. Finally, we observe that the so-called
"seed" conformal blocks for constructing four point functions for operators
with arbitrary space-time spins in four dimensional CFTs can also be linearly
expanded in terms of Calogero-Sutherland eigenfunctions.


title:
Detecting Violent and Abnormal Crowd activity using Temporal Analysis of
  Grey Level Co-occurrence Matrix (GLCM) Based Texture Measures

abstract:
  The severity of sustained injury resulting from assault-related violence can
be minimised by reducing detection time. However, it has been shown that human
operators perform poorly at detecting events found in video footage when
presented with simultaneous feeds. We utilise computer vision techniques to
develop an automated method of abnormal crowd detection that can aid a human
operator in the detection of violent behaviour. We observed that behaviour in
city centre environments often occur in crowded areas, resulting in individual
actions being occluded by other crowd members. We propose a real-time
descriptor that models crowd dynamics by encoding changes in crowd texture
using temporal summaries of Grey Level Co-Occurrence Matrix (GLCM) features. We
introduce a measure of inter-frame uniformity (IFU) and demonstrate that the
appearance of violent behaviour changes in a less uniform manner when compared
to other types of crowd behaviour. Our proposed method is computationally cheap
and offers real-time description. Evaluating our method using a privately held
CCTV dataset and the publicly available Violent Flows, UCF Web Abnormality, and
UMN Abnormal Crowd datasets, we report a receiver operating characteristic
score of 0.9782, 0.9403, 0.8218 and 0.9956 respectively.


title:
Magnetic properties of perovskites
  La$_{0.7}$Sr$_{0.3}$Mn$_{0.7}^{3+}$Mn$_{0.3-x}^{4+}$Ti$_x$O$_3$:Monte Carlo
  simulation versus experiments

abstract:
  This work presents a Monte Carlo study of the phase transition in the
perovskites La$_{0.7}$Sr$_{0.3}$Mn$_{0.7}^{3+}$Mn$_{0.3-x}^{4+}$Ti$_x$O$_3$
($x$= 0.1, 0.2, and 0.25). We take into accountnearest-neighbor (NN)
interactions between magnetic ions Mn$^{3+}$($S=2$) and Mn$^{4+}$($S=3/2$)
using a spin model describing a strong anisotropy on the $z$ axis. We have
calculated the uniform and staggered magnetizations as well as the
Edwards-Anderson order parameter as functions of temperature, with and without
an applied magnetic field. Fitting the experimental Curie temperature at $x=0$,
we estimated values of various exchange interactions in the system. The
dominant one is that between Mn$^{3+}$ and Mn$^{4+}$ which is at the origin of
the ferromagnetic ordering. Effects of the very small interaction $J\_2$
between NN Mn$^{3+}$ is analyzed: we show that it can cause an
antiferromagnetic phase above $T\_c$ which disappears at smaller $J\_2$ or at
Mn$^{3+}$ concentrations smaller than 0.55. Our results show a good agreement
with experiments on the magnetizations for substitution concentration $x=0.1$,
0.2 and 0.3. We also studied the applied-field effect on the magnetization and
our obtained results are compared with experiments performed at $x=10\%$.


title: Rate of convergence for polymers in a weak disorder

abstract:
  We consider directed polymers in random environment on the lattice Z d at
small inverse temperature and dimension d $\ge$ 3. Then, the normalized
partition function W n is a regular martingale with limit W. We prove that n
(d--2)/4 (W n -- W)/W n converges in distribution to a Gaussian law. Both the
polynomial rate of convergence and the scaling with the martingale W n are
different from those for polymers on trees.


title:
Near-Linear Lower Bounds for Distributed Distance Computations, Even in
  Sparse Networks

abstract:
  We develop a new technique for constructing sparse graphs that allow us to
prove near-linear lower bounds on the round complexity of computing distances
in the CONGEST model. Specifically, we show an $\widetilde{\Omega}(n)$ lower
bound for computing the diameter in sparse networks, which was previously known
only for dense networks [Frishknecht et al., SODA 2012]. In fact, we can even
modify our construction to obtain graphs with constant degree, using a simple
but powerful degree-reduction technique which we define.
  Moreover, our technique allows us to show $\widetilde{\Omega}(n)$ lower
bounds for computing $(\frac{3}{2}-\varepsilon)$-approximations of the diameter
or the radius, and for computing a $(\frac{5}{3}-\varepsilon)$-approximation of
all eccentricities. For radius, we are unaware of any previous lower bounds.
For diameter, these greatly improve upon previous lower bounds and are tight up
to polylogarithmic factors [Frishknecht et al., SODA 2012], and for
eccentricities the improvement is both in the lower bound and in the
approximation factor [Holzer and Wattenhofer, PODC 2012].
  Interestingly, our technique also allows showing an almost-linear lower bound
for the verification of $(\alpha,\beta)$-spanners, for $\alpha < \beta+1$.


title:
Incorporating Loose-Structured Knowledge into Conversation Modeling via
  Recall-Gate LSTM

abstract:
  Modeling human conversations is the essence for building satisfying chat-bots
with multi-turn dialog ability. Conversation modeling will notably benefit from
domain knowledge since the relationships between sentences can be clarified due
to semantic hints introduced by knowledge. In this paper, a deep neural network
is proposed to incorporate background knowledge for conversation modeling.
Through a specially designed Recall gate, domain knowledge can be transformed
into the extra global memory of Long Short-Term Memory (LSTM), so as to enhance
LSTM by cooperating with its local memory to capture the implicit semantic
relevance between sentences within conversations. In addition, this paper
introduces the loose structured domain knowledge base, which can be built with
slight amount of manual work and easily adopted by the Recall gate. Our model
is evaluated on the context-oriented response selecting task, and experimental
results on both two datasets have shown that our approach is promising for
modeling human conversations and building key components of automatic chatting
systems.


title:
Pressure-induced gap closing and metallization of MoSe$_{2}$ and
  MoTe$_{2}$

abstract:
  Layered molybdenum dichalchogenides are semiconductors whose gap is
controlled by delicate interlayer interactions. The gap tends to drop together
with the interlayer distance, suggesting collapse and metallization under
pressure. We predict, based on first principles calculations, that layered
semiconductors 2H$_c$-MoSe$_2$ and 2H$_c$-MoTe$_2$ should undergo metallization
at pressures between 28 and 40 GPa (MoSe$_2$) and 13 and 19 GPa (MoTe$_2$).
Unlike MoS$_2$ where a 2H$_c$ $\to$ 2H$_a$ layer sliding transition is known to
take place, these two materials appear to preserve the original 2H$_c$ layered
structure at least up to 100 GPa and to increasingly resist lubric layer
sliding under pressure. Similar to metallized MoS$_2$ they are predicted to
exhibit a low density of states at the Fermi level, and presumably very modest
superconducting temperatures if any. We also study the $\beta$-MoTe$_2$
structure, metastable with a higher enthalpy than 2H$_c$-MoTe$_2$. Despite its
ready semimetallic and (weakly) superconducting character already at zero
pressure, metallicity is not expected to increase dramatically with pressure.


title: Homotopically discrete higher categorical structures

abstract:
  We introduce the notion of homotopically discrete n-fold category as an
n-fold generalization of a groupoid with no non-trivial loops. We give two
equivalent descriptions of this structure: in terms of a Segal-type model and
in terms of iterated internal equivalence relations. We also show that
homotopically discrete n-fold categories form an n-fold categorical model of
0-types.


title: Remarks on the $P_c$ structures and triangle singularities

abstract:
  It was proposed that the narrow $P_c(4450)$ structure observed by the LHCb
Collaboration in the reaction $\Lambda_b\to J/\psi p K$ might be due to a
triangle singularity around the $\chi_{c1}$--proton threshold at 4.45~GeV. We
discuss the occurrence of a similar triangle singularity in the $J/\psi p$
invariant mass distribution for the decay $\Lambda_b\to J/\psi p \pi$, which
could explain the bump around 4.45~GeV in the data. More precise measurements
of this process would provide valuable information towards an understanding of
the $P_c$ structures.


title: Growth of Dimension in Complete Simple Games

abstract:
  The concept of dimension in simple games was introduced as a measure of the
remoteness of a given game from a weighted game. Taylor and Zwicker (1993)
demonstrated that the dimension of a simple game can grow exponentially in the
number of players. However, the problem of worst-case growth of the dimension
in complete games was left open. Freixas and Puente (2008) showed that complete
games of arbitrary dimension exist and, in particular, their examples
demonstrate that the worst-case growth of dimension in complete games is at
least linear. In this paper, using a novel technique of Kurz and Napel (2016),
we demonstrate that the worst-case growth of dimension in complete simple games
is exponential in the number of players.


title:
Inverse scattering at fixed energy on three-dimensional asymptotically
  hyperbolic St{\"a}ckel manifolds

abstract:
  In this paper, we study an inverse scattering problem at fixed energy on
three-dimensional asymptotically hyperbolic St{\"a}ckel manifolds having the
topology of toric cylinders and satisfying the Robertson condition. On these
manifolds the Helmholtz equation can be separated into a system of a radial ODE
and two angular ODEs. We can thus decompose the full scattering operator onto
generalized harmonics and the resulting partial scattering matrices consist in
a countable set of $2 \times 2$ matrices whose coefficients are the so-called
transmission and reflection coefficients. It is shown that the reflection
coefficients are nothing but generalized Weyl-Titchmarsh functions associated
with the radial ODE. Using a novel multivariable version of the Complex Angular
Momentum method, we show that the knowledge of the scattering operator at a
fixed non-zero energy is enough to determine uniquely the metric of the
three-dimensional St{\"a}ckel manifold up to natural obstructions.


title: New Class of SO(10) Models for Flavor

abstract:
  We present a new class of unified models based on SO(10) symmetry which
provides insights into the masses and mixings of quarks and leptons, including
the neutrinos. The key feature of our proposal is the absence of Higgs boson
10_H belonging to the fundamental representation that is normally employed.
Flavor mixing is induced via vector-like fermions in the 16 + 16-bar
representation. A variety of scenarios, both supersymmetric and otherwise, are
analyzed involving a 126_H along with either a 45_H or a 210_H of Higgs boson
employed for symmetry breaking. It is shown that this framework, with only a
limited number of parameters, provides an excellent fit to the full fermion
spectrum, utilizing either type-I or type-II seesaw mechanism. These flavor
models can be potentially tested and distinguished in their predictions for
proton decay branching ratios, which are analyzed.


title: Exact groupoids

abstract:
  Our purpose is to introduce in the setting of locally compact groupoids the
analogues of the well known equivalent definitions of exactness for discrete
groups. We study the relations between these notions. The best results are
obtained for a class of \'etale groupoids that we call inner amenable, since
for locally compact groups this notion coincides with the notion of inner
amenability. We give examples of such groupoids which include transformation
groupoids associated to actions of discrete groups by homeomorphisms on locally
compact spaces. We have no example of \'etale groupoids which are not inner
amenable. For inner amenable \'etale groupoids we extend what is known for
discrete groups in proving the equivalence of six natural notions of exactness:
(1) strong amenability at infinity; (2) amenability at infinity; (3) nuclearity
of the uniform (Roe) algebra of the groupoid; (4) exactness of this
$C^*$-algebra; (5) exactness of the reduced $C^*$-algebra; (6) exactness of the
groupoid in the sense of Kirchberg-Wassermann.
  We give several illustrations of our results and review the results obtained
by several authors that highlight the crucial role of exactness in order to
clarify the relation between the amenability of a groupoid and the fact that
its full and reduced $C^*$-algebras coincide. We end our paper with open
questions and an appendix on fibrewise compactifications because our work
requires to extend from discrete groups to \'etale groupoids the notion of
Stone-Cech compactification on which the groupoid acts.


title: Lossless Compression in HEVC with Integer-to-Integer Transforms

abstract:
  Many approaches have been proposed to support lossless coding within video
coding standards that are primarily designed for lossy coding. The simplest
approach is to just skip transform and quantization and directly entropy code
the prediction residual, which is used in HEVC version 1. However, this simple
approach is inefficient for compression. More efficient approaches include
processing the residual with DPCM prior to entropy coding. This paper explores
an alternative approach based on processing the residual with
integer-to-integer (i2i) transforms. I2i transforms map integers to integers,
however, unlike the integer transforms used in HEVC for lossy coding, they do
not increase the dynamic range at the output and can be used in lossless
coding. Experiments with the HEVC reference software show competitive results.


title:
The Quantum Black Hole as a Hydrogen Atom: Microstates Without Strings
  Attached

abstract:
  Applying an expansion in spherical harmonics, turns the black hole with its
microstates into something about as transparent as the hydrogen atom was in the
early days of quantum mechanics. It enables us to present a concise description
of the evolution laws of these microstates, linking them to perturbative
quantum field theory, in the background of the Schwarzschild metric. Three
pieces of insight are obtained: One, we learn how the gravitational back
reaction, whose dominant component can be calculated exactly, turns particles
entering the hole, into particles leaving it, by exchanging the momentum- and
position operators; two, we find out how this effect removes firewalls, both on
the future and the past event horizon, and three, we discover that the presence
of region II in the Penrose diagram forces a topological twist in the
background metric, culminating in antipodal identification. Although a cut-off
is required that effectively replaces the transverse coordinates by a lattice,
the effect of such a cut-off minimizes when the spherical wave expansion is
applied. This expansion then reveals exactly how antipodal identification
restores unitarity - for each partial wave separately. We expect that these
ideas will provide new insights in some highly non-trivial topological
space-time features at the Planck scale.


title: Pushing the limits of the CyberGrasp for haptic rendering

abstract:
  The CyberGrasp is a well known dataglove-exoskeleton device combination that
allows to render haptic feedback to the human fingers. Its design, however,
restricts its usability for teleoperation through a limited control bandwidth
and position sensor resolution. Therefore the system is restricted to low
achievable contact stiffness and feedback gain magnitudes in haptic rendering.
Moreover, the system prohibits simple adaption of its controller
implementation. In this paper, the ExHand Box is presented, a newly designed
back-end to widen the CyberGrasp's bandwidth restrictions and to open it up for
fully customized controller implementations. The ExHand Box provides a new
computer, interface electronics and motor controllers for the otherwise
unmodified CyberGlove and CyberGrasp hand systems. The loop frequency of the
new system can be freely varied up to 2 kHz and custom controllers can be
implemented through an automatic code generation interface. System performance
identification experiments are presented that demonstrate improved behavior in
hard contact situations over a range of sampling periods. Maximum contact
stiffnesses of up to 50kN/m in a stable condition are demonstrated, which is
significantly higher than what could be achieved with the non-customized
original system version. Moreover, a bilateral control experiment is conducted
to demonstrate the new system's usability for generic teleoperation research.
In this experiment a raycasting algorithm is introduced for pre-contact
detection in order to compensate for high delay and jitter communication links
between master and slave as they appear in an Ethernet network. It is
demonstrated that the contact stiffness can be maintained in the order of
magnitude of the system performance identification with a demonstrated
stiffness of 41kN/m in a stable condition.


title: Selectively Balancing Unit Vectors

abstract:
  A set $U$ of unit vectors is selectively balancing if one can find two
disjoint subsets $U^+$ and $U^-$, not both empty, such that the Euclidean
distance between the sum of $U^+$ and the sum of $U^-$ is smaller than $1$. We
prove that the minimum number of unit vectors that guarantee a selectively
balancing set in $\mathbb{R}^n$ is asymptotically $\frac{1}{2} n \log n$.


title: Two-Finger Keyboard Layout Problem: An Application On Turkish Language

abstract:
  Smart phone and tablet usage has sharply increased for the last decade. While
entering test on these devices, virtual keyboards are generally used instead of
conventional hardware keyboards. In this study, a new problem which is
two-finger keyboard layout problem and solution approach is presented for
increasing user test entrance performance, especially on virtual keyboards.
Defined two-finger keyboard layout problem is modeled as Quadratic Assignment
Problem. Because of combinatorial structure of the problem a genetic algorithm
is developed. Its result is given to mathematical model as initial solution for
finding better solutions with mathematical model. Proposed approach is applied
on Turkish language. The new two finger keyboard layout for Turkish language is
compared with F and QWERTY keyboard layouts based on certain performance
measurement techniques.


title:
The New Multi-Edge Metric-Constrained PEG/QC-PEG Algorithms for
  Designing the Binary LDPC Codes With Better Cycle-Structures

abstract:
  To obtain a better cycle-structure is still a challenge for the low-density
parity-check (LDPC) code design. This paper formulates two metrics firstly so
that the progressive edge-growth (PEG) algorithm and the approximate cycle
extrinsic message degree (ACE) constrained PEG algorithm are unified into one
integrated algorithm, called the metric-constrained PEG algorithm (M-PEGA).
Then, as an improvement for the M-PEGA, the multi-edge metric-constrained PEG
algorithm (MM-PEGA) is proposed based on two new concepts, the multi-edge local
girth and the edge-trials. The MM-PEGA with the edge-trials, say a positive
integer $r$, is called the $r$-edge M-PEGA, which constructs each edge of the
non-quasi-cyclic (non-QC) LDPC code graph through selecting a check node whose
$r$-edge local girth is optimal. In addition, to design the QC-LDPC codes with
any predefined valid design parameters, as well as to detect and even to avoid
generating the undetectable cycles in the QC-LDPC codes designed by the QC-PEG
algorithm, the multi-edge metric constrained QC-PEG algorithm (MM-QC-PEGA) is
proposed lastly. It is verified by the simulation results that increasing the
edge-trials of the MM-PEGA/MM-QC-PEGA is expected to have a positive effect on
the cycle-structures and the error performances of the LDPC codes designed by
the MM-PEGA/MM-QC-PEGA.


title:
Universal rules for visible-light absorption in hybrid perovskite
  materials

abstract:
  A variety of organic-inorganic hybrid perovskites (APbX3) consisting of mixed
center cations [A = CH3NH3+, HC(NH2)2+, Cs+] with different PbX3- cages (X = I,
Br, Cl) have been developed to realize high-efficiency solar cells.
Nevertheless, clear understanding for the effects of A and X on the optical
transition has been lacking. Here, we present universal rules that allow the
unified interpretation of the optical absorption in various hybrid perovskites.
In particular, we find that the influence of the A-site cation on the light
absorption is rather significant and the absorption coefficient (alpha) reduces
to half when CH3NH3+ is replaced with HC(NH2)2+ in the APbI3 system. Our
density functional theory (DFT) calculations reproduce all of the fine
absorption features observed in HC(NH2)2PbI3 and CH3NH3PbBr3, allowing the
unique assignment of the interband transitions in the Brillouin zone. In
contrast to general understanding that the A-site cation involves weakly in the
optical process, our theoretical calculations reveal that the center cation
plays a critical role in the interband transition and the absorption strength
in the visible region is modified by the strong A-X interaction. Furthermore,
our systematic analyses show that the variation of the absorption spectrum with
X can be described simply by the well-known sum rule. The universal rules
established in this study explain the large reduction of alpha in HC(NH2)2PbI3
and predict CsPbI3 as the highest alpha material.


title:
Evidence that the maximum electron energy in hotspots of FR II galaxies
  is not determined by synchrotron cooling

abstract:
  It has been suggested that relativistic shocks in extragalactic sources may
accelerate the highest energy cosmic rays. The maximum energy to which cosmic
rays can be accelerated depends on the structure of magnetic turbulence near
the shock but recent theoretical advances indicate that relativistic shocks are
probably unable to accelerate particles to energies much larger than a PeV. We
study the hotspots of powerful radiogalaxies, where electrons accelerated at
the termination shock emit synchrotron radiation. The turnover of the
synchrotron spectrum is typically observed between infrared and optical
frequencies, indicating that the maximum energy of non-thermal electrons
accelerated at the shock is < TeV for a canonical magnetic field of ~100 micro
Gauss. Based on theoretical considerations we show that this maximum energy
cannot be constrained by synchrotron losses as usually assumed, unless the jet
density is unreasonably large and most of the jet upstream energy goes to
non-thermal particles. We test this result by considering a sample of hotspots
observed with high spatial resolution at radio, infrared and optical
wavelengths.


title: Critical Casimir interactions between Janus particles

abstract:
  Recently there is strong experimental and theoretical interest in studying
the self-assembly and the phase behavior of patchy and of Janus particles,
which form colloidal suspensions. Although in this quest a variety of effective
interactions have been proposed and used in order to achieve directed assembly,
the critical Casimir effect stands out as being particularly suitable in this
respect because it provides both attractive and repulsive interactions as well
as the potential of a sensitive temperature control of their strength.
Specifically, we have calculated the critical Casimir force between a single
Janus particle and a laterally homogeneous substrate as well as a substrate
with a chemical step. We have used the Derjaguin approximation and compared it
with results from full mean field theory. A modification of the Derjaguin
approximation turns out to be generally reliable. Based on this approach we
have derived the effective force and the effective potential between two Janus
cylinders as well as between two Janus spheres.


title:
Anisotropy of Low Energy Direct Photons in Relativistic Heavy Ion
  Collisions

abstract:
  We investigate the behavior of low energy photons radiated by the
deceleration processes of two colliding nuclei in relativistic heavy ion
collisions using the Wigner function approach for electromagnetic radiation
fields. The angular distribution reveals the information of the initial
geometric configurations. Such a property is reflected in the anisotropic
parameter $v_{2}$, showing an increasing $v_{2}$ as energy decreases, which is
a behavior qualitatively different from $v_{2}$ from hadrons produced in the
collisions.


title:
Structural and magnetic study of PrMn$_{1-x}$Fe$_x$O$_3$ $(0 \leq x \leq
  1)$ compounds

abstract:
  The structural and magnetic study of PrMn1-xFexO3(0 <= x <= 1) substitutional
orthorhombical system, was performed on polycrystalline (x <= 0.5) as well as
on the single crystalline (0.5 <= x <= 1) samples.


title:
A NLTE line formation for neutral and singly-ionised titanium in model
  atmospheres of the reference A-K stars

abstract:
  We construct a comprehensive model atom for TiI-II using more than 3600
measured and predicted energy levels of TiI and 1800 energy levels of TiII, and
quantum mechanical photoionisation cross-sections. Non-local thermodynamical
equilibrium (NLTE) line formation for the two ions of titanium is treated
through a wide range of spectral types from A to K, including metal-poor stars
with [Fe/H] down to -2.6 dex. NLTE leads to systematically depleted total
absorption in the TiI lines and to positive abundance corrections. The
magnitude of NLTE abundance corrections is smaller compared to the available
literature data for the cool (FGK type) atmospheres. NLTE leads to strengthened
TiII lines and to negative NLTE abundance corrections. For the first time, we
performed the NLTE calculations for TiI-II in the 6500 K < Teff < 13000 K
range. The deviations from LTE grow towards higher effective temperature. For
four A type stars we derived the NLTE and LTE abundances from lines of TiI and
TiII. In LTE an abundance discrepancy of up to 0.22 dex was obtained between
TiI and TiII, and it vanishes in NLTE. For other four A-B stars, with only TiII
lines observed, NLTE leads to smaller line-to-line scatter compared to LTE. An
efficiency of inelastic TiI + HI collisions was empirically estimated from
analysis of TiI and TiII lines in 17 cool stars in a wide metallicity range
-2.6 < [Fe/H] < 0.0. Consistent NLTE abundances from lines of TiI and TiII were
obtained applying classical Drawinian rates for the stars with log g > 4.1, and
neglecting inelastic collisions with HI for the VMP giant HD 122563. For the
very metal-poor turn-off stars ([Fe/H] < -2 and log g < 4.1), the abundance
difference TiI-TiII was obtained to be positive already in LTE and it increases
in NLTE. The accurate collisional data for TiI and TiII are desired to find a
clue to this problem.


title: Bernstein-Zelevinsky derivatives, branching rules and Hecke algebras

abstract:
  Let $G$ be a split reductive group over a $p$-adic field $F$. Let $B$ be a
Borel subgroup and $U$ the maximal unipotent subgroup of $B$.
  Let $\psi$ be a Whittaker character of $U$. Let $I$ be an Iwahori subgroup of
$G$. We describe the Iwahori-Hecke algebra action on the Gelfand-Graev
representation $(\mathrm{ind}_{U}^{G}\psi)^I$ by an explicit projective module.
As a consequence, for $G=GL(n,F)$, we define and describe Bernstein-Zelevinsky
derivatives of representations generated by $I$-fixed vectors in terms of the
corresponding Iwahori-Hecke algebra modules. Furthermore, using Lusztig's
reductions, we show that the Bernstein-Zelevinsky derivatives can be determined
using graded Hecke algebras.
  We give two applications of our study. Firstly, we compute the
Bernstein-Zelevinsky derivatives of generalized Speh modules, which recovers a
result of Lapid-M\'inguez and Tadi\'c. Secondly, we give a realization of the
Iwahori-Hecke algebra action on some generic representations of $GL(n+1,F)$,
restricted to $GL(n,F)$, which is further used to verify a conjecture on an
Ext-branching problem of D. Prasad for a class of examples.


title: A note on sums of three square-zero matrices

abstract:
  It is known that every complex trace-zero matrix is the sum of four
square-zero matrices, but not necessarily of three such matrices. In this note,
we prove that for every trace-zero matrix $A$ over an arbitrary field, there is
a non-negative integer $p$ such that the extended matrix $A \oplus 0_p$ is the
sum of three square-zero matrices (more precisely, one can simply take $p$ as
the number of rows of $A$). Moreover, we demonstrate that if the underlying
field has characteristic $2$ then every trace-zero matrix is the sum of three
square-zero matrices. We also discuss a counterpart of the latter result for
sums of idempotents.


title:
Single-atom single-photon coupling facilitated by atomic-ensemble
  dark-state mechanisms

abstract:
  We propose to couple single atomic qubits to photons incident on a cavity
containing an atomic ensemble of a different species that mediates the coupling
via Rydberg interactions. Subject to a classical field and the cavity field,
the ensemble forms a collective dark state which is resonant with the input
photon, while excitation of a qubit atom leads to a secondary "dark" state that
splits the cavity resonance. The two different dark state mechanisms yield zero
and $\pi$ reflection phase shifts and can be used to implement quantum gates
between atomic and optical qubits.


title:
Conformal perturbation of off-critical correlators in the 3D Ising
  universality class

abstract:
  Thanks to the impressive progress of conformal bootstrap methods we have now
very precise estimates of both scaling dimensions and OPE coefficients for
several 3D universality classes. We show how to use this information to obtain
similarly precise estimates for off-critical correlators using conformal
perturbation. We discuss in particular the $< \sigma (r) \sigma (0) >$, $<
\epsilon (r) \epsilon (0) >$ and $< \sigma (r) \epsilon (0) >$ two point
functions in the high and low temperature regimes of the 3D Ising model and
evaluate the leading and next to leading terms in the $s = t r^{\Delta_{t}}$
expansion, where $t$ is the reduced temperature. Our results for $< \sigma (r)
\sigma (0) >$ agree both with Monte Carlo simulations and with a set of
experimental estimates of the critical scattering function.


title:
A Semi-automatic Method for Efficient Detection of Stories on Social
  Media

abstract:
  Twitter has become one of the main sources of news for many people. As
real-world events and emergencies unfold, Twitter is abuzz with hundreds of
thousands of stories about the events. Some of these stories are harmless,
while others could potentially be life-saving or sources of malicious rumors.
Thus, it is critically important to be able to efficiently track stories that
spread on Twitter during these events. In this paper, we present a novel
semi-automatic tool that enables users to efficiently identify and track
stories about real-world events on Twitter. We ran a user study with 25
participants, demonstrating that compared to more conventional methods, our
tool can increase the speed and the accuracy with which users can track stories
about real-world events.


title: Self-current induced spin-orbit torque in FeMn/Pt multilayers

abstract:
  Extensive efforts have been devoted to the study of spin-orbit torque in
ferromagnetic metal/heavy metal bilayers and exploitation of it for
magnetization switching using an in-plane current. As the spin-orbit torque is
inversely proportional to the thickness of the ferromagnetic layer, sizable
effect has only been realized in bilayers with an ultrathin ferromagnetic
layer. Here we demonstrate that, by stacking ultrathin Pt and FeMn alternately,
both ferromagnetic properties and current induced spin-orbit torque can be
achieved in FeMn/Pt multilayers without any constraint on its total thickness.
The critical behavior of these multilayers follows closely three-dimensional
Heisenberg model with a finite Curie temperature distribution. The spin torque
effective field is about 4 times larger than that of NiFe/Pt bilayer with a
same equivalent NiFe thickness. The self-current generated spin torque is able
to switch the magnetization reversibly without the need for an external field
or a thick heavy metal layer. The removal of both thickness constraint and
necessity of using an adjacent heavy metal layer opens new possibilities for
exploiting spin-orbit torque for practical applications.


title: Random walks on the BMW monoid: an algebraic approach

abstract:
  We consider Metropolis-based systematic scan algorithms for generating
Birman-Murakami-Wenzl (BMW) monoid basis elements of the BMW algebra. As the
BMW monoid consists of tangle diagrams, these scanning strategies can be
rephrased as random walks on links and tangles. We translate these walks into
left multiplication operators in the corresponding BMW algebra. Taking this
algebraic perspective enables the use of tools from representation theory to
analyze the walks; in particular, we develop a norm arising from a trace
function on the BMW algebra to analyze the time to stationarity of the walks.


title:
User Scheduling and Optimal Power Allocation for Full-Duplex Cellular
  Networks

abstract:
  The problem of user scheduling and power allocation in full-duplex (FD)
cellular networks is considered, where a FD base station communicates
simultaneously with one half-duplex (HD) user on each downlink and uplink
channel. First, we propose low complexity user scheduling algorithms aiming at
maximizing the sum rate of the considered FD system. Second, we derive the
optimal power allocation for the two communication links, which is then
exploited to introduce efficient metrics for FD/HD mode switching in the
scheduling procedure, in order to further boost the system rate performance. We
analyze the average sum rate of the proposed algorithms over Rayleigh fading
and provide closed-form expressions. Our representative performance evaluation
results for the algorithms with and without optimal power control offer useful
insights on the interplay among rate, transmit powers, self-interference (SI)
cancellation capability, and available number of users in the system.


title: Quench of symmetry broken ground states

abstract:
  We analyze the problem of how different ground states associated to the same
set of the Hamiltonian parameters evolve after a sudden quench. To realize our
analysis we define a quantitative approach to the local distinguishability
between different ground states of a magnetically ordered phase in terms of the
trace distance between the reduced density matrices obtained projecting two
ground states in the same subset. Before the quench, regardless the particular
choice of the subset, any system in a magnetically ordered phase is
characterized by ground states that are locally distinguishable. On the other
hand, after the quench, the maximum of the distinguishability shows an
exponential decay in time. Hence, in the limit of very large time, all the
informations about the particular initial ground state are lost even if the
systems are integrable. We prove our claims in the framework of the
magnetically ordered phases that characterize both the $XY$ model and
$N$-cluster Ising models. The fact that we find similar behavior in models
within different classes of symmetry makes us confident about the generality of
our results.


title: Two Roads Diverged: A Semantic Network Analysis of Guanxi on Twitter

abstract:
  Guanxi, roughly translated as "social connection", is a term commonly used in
the Chinese language. In this research, we employed a linguistic approach to
explore popular discourses on Guanxi. Although sharing the same Confucian
roots, Chinese communities inside and outside Mainland China have undergone
different historical trajectories. Hence, we took a comparative approach to
examine guanxi in Mainland China and in Taiwan, Hong Kong, and Macau (TW-HK-M).
Comparing guanxi discourses in two Chinese societies aims at revealing the
divergence of guanxi culture. The data for this research were collected on
Twitter over a three-week period by searching tweets containing guanxi written
in Simplified Chinese characters and in Traditional Chinese characters. After
building, visualising, and conducting community detection on both semantic
networks, two guanxi discourses were then compared in terms of their major
concept sub-communities. This research aims at addressing two questions: Has
the meaning of guanxi transformed in contemporary Chinese societies? And how do
different socio-economic configurations affect the practice of guanxi? Results
suggest that guanxi in interpersonal relationships has adapted to a new family
structure in both Chinese societies. In addition, the practice of guanxi in
business varies in Mainland China and in TW-HK-M. Furthermore, an extended
domain was identified where guanxi is used in a macro-level discussion of state
relations. Network representations of the guanxi discourses enabled reification
of the concept and shed lights on the understanding of social connections and
social orders in contemporary China.

categories: physics.soc-ph cs.CY cs.SI physics.data-an


title: Metastability in the reversible inclusion process

abstract:
  We study the condensation regime of the finite reversible inclusion process,
i.e., the inclusion process on a finite graph $S$ with an underlying random
walk that admits a reversible measure. We assume that the random walk kernel is
irreducible and its reversible measure takes maximum value on a subset of
vertices $S_\star\subset S$. We consider initial conditions corresponding to a
single condensate that is localized on one of those vertices and study the
metastable (or tunneling) dynamics. We find that, if the random walk restricted
to $S_\star$ is irreducible, then there exists a single time-scale for the
condensate motion. In this case we compute this typical time-scale and
characterize the law of the (properly rescaled) limiting process. If the
restriction of the random walk to $S_\star$ has several connected components, a
metastability scenario with multiple time-scales emerges. We prove such a
scenario, involving two additional time-scales, in a one-dimensional setting
with two metastable states and nearest-neighbor jumps.


title: A user's guide to the topological Tverberg conjecture

abstract:
  The topological Tverberg conjecture was considered a central unsolved problem
of topological combinatorics. The conjecture asserts that for any integers
$r,d>1$ and any continuous map $f:\Delta\to\mathbb R^d$ of the
$(d+1)(r-1)$-dimensional simplex there are pairwise disjoint faces
$\sigma_1,\ldots,\sigma_r\subset\Delta$ such that $f(\sigma_1)\cap \ldots \cap
f(\sigma_r)\ne\emptyset$.
  The conjecture was proved for a prime power $r$. Recently counterexamples for
other $r$ were found. Analogously, the $r$-fold van Kampen-Flores conjecture
holds for a prime power $r$ but does not hold for other $r$. The arguments form
a beautiful and fruitful interplay between combinatorics, algebra and topology.
We present a simplified exposition accessible to non-specialists in the area.
We also mention some recent developments and open problems.


title:
Automatic Classification of Irregularly Sampled Time Series with Unequal
  Lengths: A Case Study on Estimated Glomerular Filtration Rate

abstract:
  A patient's estimated glomerular filtration rate (eGFR) can provide important
information about disease progression and kidney function. Traditionally, an
eGFR time series is interpreted by a human expert labelling it as stable or
unstable. While this approach works for individual patients, the time consuming
nature of it precludes the quick evaluation of risk in large numbers of
patients. However, automating this process poses significant challenges as eGFR
measurements are usually recorded at irregular intervals and the series of
measurements differs in length between patients. Here we present a two-tier
system to automatically classify an eGFR trend. First, we model the time series
using Gaussian process regression (GPR) to fill in `gaps' by resampling a fixed
size vector of fifty time-dependent observations. Second, we classify the
resampled eGFR time series using a K-NN/SVM classifier, and evaluate its
performance via 5-fold cross validation. Using this approach we achieved an
F-score of 0.90, compared to 0.96 for 5 human experts when scored amongst
themselves.


title: Involutions and higher order automorphisms of Higgs bundle moduli spaces

abstract:
  We consider the moduli space $\mathcal{M}(G)$ of $G$-Higgs bundles over a
compact Riemann surface $X$, where $G$ is a complex semisimple Lie group. This
is a hyperk\"ahler manifold homeomorphic to the moduli space $\mathcal{R}(G)$
of representations of the fundamental group of $X$ in $G$. In this paper we
study finite order automorphisms of $\mathcal{M}(G)$ obtained by combining the
action of an element of order $n$ in $H^1(X,Z)\rtimes \mbox{Out}(G)$, where $Z$
is the centre of $G$ and $\mbox{Out}(G)$ is the group of outer automorphisms of
$G$, with the multiplication of the Higgs field by an $n$th-root of unity, and
describe the subvarieties of fixed points. We give special attention to the
case of involutions, defined by the action of an element of order $2$ in
$H^1(X,Z)\rtimes\mbox{Out}(G)$ combined with the multiplication of the Higgs
field by $\pm 1$. In this situation, the subvarieties of fixed points are
hyperk\"ahler submanifolds of $\mathcal{M}(G)$ in the (+1)-case, corresponding
to the moduli space of representations of the fundamental group in certain
reductive complex subgroups of $G$ defined by holomorphic involutions of $G$;
while in the (-1)-case they are Lagrangian subvarieties corresponding to the
moduli space of representations of the fundamental group of $X$ in real forms
of $G$ and certain extensions of these. We illustrate the general theory with
the description of involutions for $G=\mbox{SL}(n,\mathbb{C})$ and involutions
and order three automorphism defined by triality for
$G=\mbox{Spin}(8,\mathbb{C})$.


title: Process tomography of quantum channels using classical light

abstract:
  High-dimensional entanglement with spatial modes of light promises increased
security and information capacity over quantum channels. Unfortunately,
entanglement decays due to perturbations, corrupting quantum links which cannot
be repaired without a tomography of the channel. Paradoxically, the channel
tomography itself is not possible without a working link. Here we overcome this
problem with a robust approach to characterising quantum channels by means of
classical light. Using free-space communication in a turbulent atmosphere as an
example, we show that the state evolution of classically entangled degrees of
freedom is equivalent to that of quantum entangled pho- tons, thus providing
new physical insights into the notion of classical entanglement. The analysis
of quantum channels by means of classical light in real time unravels
stochastic dynamics in terms of pure state trajectories and thus enables
precise quantum error-correction in short and long haul optical communication,
in both free-space and fibre.


title:
Long Fading Mid-Infrared Emission in Transient Coronal Line Emitters:
  Dust Echo of Tidal Disruption Flare

abstract:
  The sporadic accretion following the tidal disruption of a star by a
super-massive black hole (TDE) leads to a bright UV and soft X-ray flare in the
galactic nucleus. The gas and dust surrounding the black hole responses to such
a flare with an echo in emission lines and infrared emission. In this paper, we
report the detection of long fading mid-IR emission lasting up to 14 years
after the flare in four TDE candidates with transient coronal lines using the
WISE public data release. We estimate that the reprocessed mid-IR luminosities
are in the range between $4\times 10^{42}$ and $2\times 10^{43}$ erg~s$^{-1}$
and dust temperature in the range of 570-800K when WISE first detected these
sources three to five years after the flare. Both luminosity and dust
temperature decreases with time. We interpret the mid-IR emission as the
infrared echo of the tidal disruption flare. We estimate the UV luminosity at
the peak flare to be 1 to 30 times $10^{44}$ erg s$^{-1}$ and for warm dust
masses to be in the range of 0.05-1.3 Msun within a few parsecs. Our results
suggest that the mid-infrared echo is a general signature of TDE in the
gas-rich environment.


title:
Understanding Social-Force Model in Psychological Principles of
  Collective Behavior

abstract:
  To well understand crowd behavior, microscopic models have been developed in
recent decades, in which an individual's behavioral/psychological status can be
modeled and simulated. A well-known model is the social-force model innovated
by physical scientists (Helbing and Molnar, 1995; Helbing, Farkas and Vicsek,
2000; Helbing et al., 2002). This model has been widely accepted and mainly
used in simulation of crowd evacuation in the past decade. A problem, however,
is that the testing results of the model were not explained in consistency with
the psychological findings, resulting in misunderstanding of the model by
psychologists. This paper will bridge the gap between psychological studies and
physical explanation about this model. We reinterpret this physics-based model
from a psychological perspective, clarifying that the model is consistent with
psychological theories on stress, including time-related stress and
interpersonal stress. Based on the conception of stress, we renew the model at
both micro-and-macro level, referring to multi-agent simulation in a
microscopic sense and fluid-based analysis in a macroscopic sense. The
cognition and behavior of individual agents are critically modeled as response
to environmental stimuli. Existing simulation results such as faster-is-slower
effect will be reinterpreted by Yerkes-Dodson law, and herding and grouping
effect as well as oscillation phenomenon are further discussed for pedestrian
crowd. In brief the social-force model exhibits a bridge between the physics
laws and psychological principles regarding crowd motion, and this paper will
renew and reinterpret the model on the foundation of psychological studies.

categories: physics.soc-ph cs.MA cs.SI nlin.AO physics.flu-dyn


title:
Comment on "A study of phantom scalar field cosmology using Lie and
  Noether symmetries" [Int. J. Mod. Phys. D 25 (2016) 1650051]

abstract:
  We show that the recent results of \ [Int. J. Mod. Phys. D 25 (2016) 1650051]
on the application of Lie/Noether symmetries in scalar field cosmology are
well-known in the literature while the problem could have been solved easily
under a coordinate transformation. That follows from the property, that the
admitted group of invariant transformations of dynamical system is independent
on the coordinate system.


title: Monogamy Relation in No-disturbance Theories

abstract:
  The monogamy is a fundamental property of Bell nonlocality and contextuality.
In this article, we studied the $n$-cycle noncontextual inequalities and
generalized CHSH inequalities in detail and found the sufficient conditions for
those inequalities to be hold. According to those conditions, we provide
several kind of tradeoff relations: monogamy of generalized Bell inequalities
in non-signaling framework, monogamy of cycle type noncontextual inequalities
and monogamy between Bell inequality and noncontextual inequality in general
no-disturbance framework. At last, some generic tradeoff relations of
generalized CHSH inequalities for $n$-party physical systems, which are beyond
one-to-many scenario, are discussed.


title:
Tests of sunspot number sequences: 4. Discontinuities around 1946 in
  various sunspot number and sunspot group number reconstructions

abstract:
  We use 5 test data series to quantify putative discontinuities around 1946 in
5 annual-mean sunspot number or group number sequences. The series tested are:
the original and new versions of the Wolf/Zurich/International sunspot number
composite [$R_{ISNv1}$ and $R_{ISNv2}$] ; the corrected version of $R_{ISNv1}$
[$R_C$]; the backbone group number [$R_{BB}$]; and the group number composite
[$R_{UEA}$]. The test data are: the group number $N_G$ and total sunspot area
$A_G$ from the RGO photoheliographic data; the CaK index from re-analysis of
MWO CaII K spectroheliograms; the group number from the MWO sunspot drawings,
$N_{MWO}$; and ionospheric critical frequencies at Slough [$foF2$]. The test
data all vary with sunspot numbers, in some cases non-linearly. Tests use both
before-and-after fit-residual comparison and correlation methods, applied to
intervals iterated to minimise errors and eliminate the effect of the
discontinuity date. It is not assumed that the correction required is by a
constant factor, nor even linear in sunspot number. A non-linear correction is
required by $R_C$, $R_{BB}$ and $R_{ISNv1}$, but not by $R_{ISNv2}$ or
$R_{UEA}$. The test datasets give very similar results in all cases. By
multiplying the probability distribution functions together we obtain the
optimum correction for each data series that must be applied to
pre-discontinuity data to make them consistent with the post-discontinuity
data. It is shown that, on average, values for 1932-1943 are too small
(relative to later values) by about 12.3% for $R_{ISNv1}$ but are too large for
$R_{ISNv2}$ and $R_{BB}$ by 3.8% and 5.2%. The correction applied to generate
$R_C$ from $R_{ISNv1}$ reduces this average factor to 0.5% but does not remove
the non-linear variation, and other errors remain uncorrected. A test is
provided by $R_{UEA}$, which is identical to the RGO $N_G$ values over the
interval used.


title: Automatic Detection and Categorization of Election-Related Tweets

abstract:
  With the rise in popularity of public social media and micro-blogging
services, most notably Twitter, the people have found a venue to hear and be
heard by their peers without an intermediary. As a consequence, and aided by
the public nature of Twitter, political scientists now potentially have the
means to analyse and understand the narratives that organically form, spread
and decline among the public in a political campaign. However, the volume and
diversity of the conversation on Twitter, combined with its noisy and
idiosyncratic nature, make this a hard task. Thus, advanced data mining and
language processing techniques are required to process and analyse the data. In
this paper, we present and evaluate a technical framework, based on recent
advances in deep neural networks, for identifying and analysing
election-related conversation on Twitter on a continuous, longitudinal basis.
Our models can detect election-related tweets with an F-score of 0.92 and can
categorize these tweets into 22 topics with an F-score of 0.90.


title:
Mass-loss of an isolated gravitating system due to energy carried away
  by gravitational waves with a cosmological constant

abstract:
  We derive the asymptotic solutions for vacuum spacetimes with non-zero
cosmological constant $\Lambda$, using the Newman-Penrose formalism. Our
approach is based exclusively on the physical spacetime, i.e. we do not
explicitly deal with conformal rescaling nor the conformal spacetime. By
investigating the Schwarzschild-de Sitter spacetime in spherical coordinates,
we subsequently stipulate the fall-offs of the null tetrad and spin
coefficients for asymptotically de Sitter spacetimes such that the terms which
would give rise to the Bondi mass-loss due to energy carried by gravitational
radiation (i.e. involving $\sigma^o$) must be non-zero. After solving the
vacuum Newman-Penrose equations asymptotically, we propose a generalisation to
the Bondi mass involving $\Lambda$ and obtain a positive-definite mass-loss
formula by integrating the Bianchi identity involving $D'\Psi_2$ over a compact
2-surface on $\mathcal{I}$. Whilst our original intention was to study
asymptotically de Sitter spacetimes, the use of spherical coordinates implies
that this readily applies for $\Lambda<0$, and yields exactly the known
asymptotically flat spacetimes when $\Lambda=0$. In other words, our asymptotic
vacuum solutions with $\Lambda\neq0$ reduce smoothly to those where
$\Lambda=0$, in spite of the distinct characters of $\mathcal{I}$ being
spacelike, timelike and null for de Sitter, anti-de Sitter and Minkowski,
respectively. Unlike for $\Lambda=0$ where no incoming radiation corresponds to
setting $\Psi^o_0=0$ on some initial null hypersurface, for $\Lambda\neq0$, no
incoming radiation requires $\Psi^o_0=0$ everywhere.


title:
Low-energy singlet sector in spin-$\frac{1}{2}$ $J_1$--$J_2$ Heisenberg
  model on square lattice

abstract:
  Based on a special variant of plaquette expansion, an operator is constructed
whose eigenvalues give the low-energy singlet spectrum of spin-$\frac12$
Heisenberg antiferromagnet on square lattice with nearest- and frustrating
next-nearest-neighbor exchange couplings $J_1$ and $J_2$. It is well known that
a non-magnetic phase arises in this model at $0.4\lesssim J_2/J_1\lesssim 0.6$
sandwiched by two N\'eel ordered phases. In agreement with previous results, we
observe a first-order quantum phase transition (QPT) at $J_2\approx 0.64J_1$
from the non-magnetic phase to the N\'eel one. Large gap ($\gtrsim0.4J_1$) is
found in the singlet spectrum at $J_2<0.64J_1$ that excludes a gapless
spin-liquid state at $0.4\lesssim J_2/J_1\lesssim 0.6$ and the deconfined
quantum criticality scenario for the QPT to another N\'eel phase. We observe a
first-order QPT at $J_2\approx 0.55J_1$ presumably between two non-magnetic
phases.


title: Optimal Switching for Hybrid Semilinear Evolutions

abstract:
  We consider the optimization of a dynamical system by switching at discrete
time points between abstract evolution equations composed by nonlinearly
perturbed strongly continuous semigroups, nonlinear state reset maps at mode
transition times and Lagrange-type cost functions including switching costs. In
particular, for a fixed sequence of modes, we derive necessary optimality
conditions using an adjoint equation based representation for the gradient of
the costs with respect to the switching times. For optimization with respect to
the mode sequence, we discuss a mode-insertion gradient. The theory unifies and
generalizes similar approaches for evolutions governed by ordinary and delay
differential equations. More importantly, it also applies to systems governed
by semilinear partial differential equations including switching the principle
part. Examples from each of these system classes are discussed.


title: Low-energy limit of the extended Linear Sigma Model

abstract:
  The extended Linear Sigma Model (eLSM) is an effective hadronic model based
on the linear realization of chiral symmetry $SU(N_f)_L \times SU(N_f)_R$, with
(pseudo)scalar and (axial-)vector mesons as degrees of freedom. In this paper,
we study the low-energy limit of the eLSM for $N_f=2$ flavors by integrating
out all fields except for the pions, the (pseudo-)Nambu--Goldstone bosons of
chiral symmetry breaking. We only keep terms entering at tree level and up to
fourth order in powers of derivatives of the pion fields. Up to this order,
there are four low-energy coupling constants in the resulting low-energy
effective action. We show that the latter is formally identical to Chiral
Perturbation Theory (ChPT), after choosing a representative for the coset space
generated by chiral symmetry breaking and expanding up to fourth order in
powers of derivatives of the pion fields. Two of the low-energy coupling
constants of the eLSM are uniquely determined by a fit to hadron masses and
decay widths. We find that their tree-level values are in reasonable agreement
with the corresponding low-energy coupling constants of ChPT. The other two
low-energy coupling constants are functions of parameters that can in principle
be determined by $\pi\pi$ scattering, which has not yet been studied within the
eLSM. Therefore, we use the respective values from ChPT to make a prediction
for the values of these parameters in the eLSM Lagrangian.


title:
Critical points of the cosmic velocity field and the uncertainties in
  the value of the Hubble constant

abstract:
  The existence of critical points for the peculiar velocity field is a natural
feature of the correlated vector field. These points appear at the junctions of
velocity domains with different orientations of their averaged velocity
vectors. Since peculiar velocities are the important cause of the scatter in
the Hubble expansion rate, we propose that a more precise determination of the
Hubble constant can be made by restricting analysis to a subsample of
observational data containing only the zones around the critical points of the
peculiar velocity field, associated with voids and saddle points. On
large-scales the critical points, where the first derivative of the
gravitational potential vanishes, can easily be identified using the density
field and classified by the behavior of the Hessian of the gravitational
potential. We use high-resolution N-body simulations to show that these regions
are stable in time and hence are excellent tracers of the initial conditions.
Furthermore, we show that the variance of the Hubble flow can be substantially
minimized by restricting observations to the subsample of such regions of
vanishing velocity instead of aiming at increasing the statistics by averaging
indiscriminately using the full data sets, as is the common approach.


title: Tweet Acts: A Speech Act Classifier for Twitter

abstract:
  Speech acts are a way to conceptualize speech as action. This holds true for
communication on any platform, including social media platforms such as
Twitter. In this paper, we explored speech act recognition on Twitter by
treating it as a multi-class classification problem. We created a taxonomy of
six speech acts for Twitter and proposed a set of semantic and syntactic
features. We trained and tested a logistic regression classifier using a data
set of manually labelled tweets. Our method achieved a state-of-the-art
performance with an average F1 score of more than $0.70$. We also explored
classifiers with three different granularities (Twitter-wide, type-specific and
topic-specific) in order to find the right balance between generalization and
overfitting for our task.


title: Monocular Urban Localization using Street View

abstract:
  This paper presents a metric global localization in the urban environment
only with a monocular camera and the Google Street View database. We fully
leverage the abundant sources from the Street View and benefits from its
topo-metric structure to build a coarse-to-fine positioning, namely a
topological place recognition process and then a metric pose estimation by
local bundle adjustment. Our method is tested on a 3 km urban environment and
demonstrates both sub-meter accuracy and robustness to viewpoint changes,
illumination and occlusion. To our knowledge, this is the first work that
studies the global urban localization simply with a single camera and Street
View.


title:
Coupling of Coexisting Non-Collinear Spin States in the Fe Monolayer on
  Re(0001)

abstract:
  Spin-polarized scanning tunneling microscopy is used to investigate the
magnetic state of the Fe monolayer on Re(0001). Two coexisting atomic-scale
non-collinear spin textures are observed with a sharp transition between them
on the order of one atomic lattice spacing. A strict position correlation
between the two spin states is observed both in experiments and in Monte Carlo
simulations, demonstrating their strong coupling behavior.


title:
Restriction and induction of indecomposable modules over the
  Temperley-Lieb algebras

abstract:
  Both the original Temperley-Lieb algebras $\mathsf{TL}_{n}$ and their dilute
counterparts $\mathsf{dTL}_{n}$ form families of filtered algebras:
$\mathsf{TL}_{n}\subset \mathsf{TL}_{n+1}$ and
$\mathsf{dTL}_{n}\subset\mathsf{dTL}_{n+1}$, for all $n\geq 0$. For each such
inclusion, the restriction and induction of every finite-dimensional
indecomposable module over $\mathsf{TL}_{n}$ (or $\mathsf{dTL}_{n}$) is
computed. To accomplish this, a thorough description of each indecomposable is
given, including its projective cover and injective hull, some short exact
sequences in which it appears, its socle and head, and its extension groups
with irreducible modules. These data are also used to prove the completeness of
the list of indecomposable modules, up to isomorphism. In fact, two
completeness proofs are given, the first is based on elementary homological
methods and the second uses Auslander-Reiten theory. The latter proof offers a
detailed example of this algebraic tool that may be of independent interest.


title:
Detection of high Lyman continuum leakage from four low-redshift compact
  star-forming galaxies

abstract:
  Following our first detection reported in Izotov et al. (2016), we present
the detection of Lyman continuum (LyC) radiation of four other compact
star-forming galaxies observed with the Cosmic Origins Spectrograph (COS)
onboard the Hubble Space Telescope (HST). These galaxies, at redshifts of
z~0.3, are characterized by high emission-line flux ratios [OIII]5007/[OII]3727
> 5. The escape fractions of the LyC radiation fesc(LyC) in these galaxies are
in the range of ~6%-13%, the highest values found so far in low-redshift
star-forming galaxies. Narrow double-peaked Lyalpha emission lines are detected
in the spectra of all four galaxies, compatible with predictions for Lyman
continuum leakers. We find escape fractions of Lyalpha, fesc(Lyalpha) ~20%-40%,
among the highest known for Lyalpha emitters (LAEs). Surface brightness
profiles produced from the COS acquisition images reveal bright star-forming
regions in the center and exponential discs in the outskirts with disc scale
lengths alpha in the range ~0.6-1.4 kpc. Our galaxies are characterized by low
metallicity, ~1/8-1/5 solar, low stellar mass ~(0.2 - 4)e9 Msun, high star
formation rates SFR~14-36 Msun/yr, and high SFR densities Sigma~2-35
Msun/yr/kpc^2. These properties are comparable to those of high-redshift
star-forming galaxies. Finally, our observations, combined with our first
detection reported in Izotov et al. (2016), reveal that a selection for compact
star-forming galaxies showing high [OIII]5007/[OII]3727 ratios appears to pick
up very efficiently sources with escaping Lyman continuum radiation: all five
of our selected galaxies are LyC leakers.


title: Self-Organized Bistability Associated With First-Order Phase Transitions

abstract:
  Self-organized criticality elucidates the conditions under which physical and
biological systems tune themselves to the edge of a second-order phase
transition, with scale invariance. Motivated by the empirical observation of
bimodal distributions of activity in neuroscience and other fields, we propose
and analyze a theory for the self-organization to the point of
phase-coexistence in systems exhibiting a first-order phase transition. It
explains the emergence of regular avalanches with attributes of
scale-invariance which coexist with huge anomalous ones, with realizations in
many fields.


title:
Electrical and optical conductivities of hole gas in $p$-doped bulk
  III-V semiconductors

abstract:
  We study electrical and optical conductivities of hole gas in $p$-doped bulk
III-V semiconductors described by the Luttinger Hamiltonian. We provide exact
analytical expressions of the Drude conductivity, inverse relaxation time for
various impurity potentials, Drude weight and optical conductivity in terms of
the Luttinger parameters $\gamma_1 $ and $\gamma_2$. The back scattering is
completely suppressed as a result of the helicity conservation of the heavy and
light hole states. We find that the inverse relaxation time of heavy holes is
much less than that of the light holes for Coulomb-type and Gaussian-type
impurity potentials and vice-versa for short-range impurity potentials. The
Drude conductivity increases non-linearly with the increase of the hole
density. The exponent of the density dependence of the conductivity is obtained
in Thomas-Fermi limit. The Drude weight varies linearly with the density even
in presence of the spin-orbit coupling. The finite-frequency optical
conductivity goes as $\sqrt{\omega}$ and its amplitude strongly depends on the
Luttinger parameters. The Luttinger parameters can be extracted from the
optical conductivity measurement.


title: Character varieties and actions on products of trees

abstract:
  It is well known that surface groups admit free and proper actions on finite
products of infinite valence trees. In this note, we address the question of
whether there can be a free and proper action on a finite product of bounded
valence trees. We provide some obstructions and an arithmetic criterion for
existence. The bulk of the paper is devoted to an approach to verifying the
arithmetic criterion by studying the character variety of certain surface
groups over fields of positive characteristic. The methods may be useful for
attempting to determine when groups admit good linear representations in other
contexts.