title:
A quantitative analysis of metrics on $\mathbf{R}^n$ with almost
  constant positive scalar curvature, with applications to fast diffusion flows

abstract:
  We prove a quantitative structure theorem for metrics on $\mathbf{R}^n$ that
are conformal to the flat metric, have almost constant positive scalar
curvature, and cannot concentrate more than one bubble. As an application of
our result, we show a quantitative rate of convergence in relative entropy for
a fast diffusion equation in $\mathbf{R}^n$ related to the Yamabe flow.


title:
Generation of light with multimode time-delayed entanglement using
  storage in a solid state spin-wave quantum memory

abstract:
  Here we demonstrate generating and storing entanglement in a solid state
spin-wave quantum memory with on-demand read out using the process of rephased
amplified spontaneous emission (RASE). Amplified spontaneous emission (ASE),
resulting from an inverted ensemble of Pr$^{3+}$ ions doped into a Y$_2$SiO$_5$
crystal, generates entanglement between collective states of the praseodymium
ensemble and the output light. The ensemble is then rephased using a four-level
photon echo technique. Entanglement between the ASE and its echo is confirmed
and the inseparability violation preserved when the RASE is stored as a
spin-wave for up to 5 $\mu$s. RASE is shown to be temporally multimode with
almost perfect distinguishability between two temporal modes demonstrated.
These results pave the way for the use of multimode solid state quantum
memories in scalable quantum networks.


title: Flag-Based Control of Quantum Purity for $n=2$ Systems

abstract:
  This paper investigates the fast Hamiltonian control of $n=2$ density
operators by continuously varying the flag as one moves away from the
completely mixed state. In general, the critical points and zeros of the purity
derivative can only be solved analytically in the limit of minimal purity. We
derive differential equations that maintain these features as the purity
increases. In particular, there is a thread of points in the Bloch ball that
locally maximizes the purity derivative, and a corresponding thread that
minimizes it. Additionally, we show there is a closed surface of points inside
of which the purity derivative is positive, and inside of which is negative. We
argue that this approach may be useful in studying higher-dimensional systems.


title: C*-algebras associated to graphs of groups

abstract:
  To a large class of graphs of groups we associate a C*-algebra universal for
generators and relations. We show that this C*-algebra is stably isomorphic to
the crossed product induced from the action of the fundamental group of the
graph of groups on the boundary of its Bass-Serre tree. We characterise when
this action is minimal, and find a sufficient condition under which it is
locally contractive. In the case of generalised Baumslag-Solitar graphs of
groups (graphs of groups in which every group is infinite cyclic) we also
characterise topological freeness of this action. We are then able to establish
a dichotomy for simple C*-algebras associated to generalised Baumslag-Solitar
graphs of groups: they are either a Kirchberg algebra, or a stable
Bunce-Deddens algebra.


title: On the Twisted KK-Theory and Positive Scalar Curvature Problem

abstract:
  Positiveness of scalar curvature and Ricci curvature requires vanishing the
obstruction $\theta(M)$ which is computed in some KK-theory of C*-algebras
index as a pairing of spin Dirac operator and Mishchenko bundle associated to
the manifold. U. Pennig had proved that the obstruction $\theta(M)$ does not
vanish if $M$ is an enlargeable closed oriented smooth manifold of even
dimension larger than or equals to 3, the universal cover of which admits a
spin structure. Using the equivariant cohomology of holonomy groupoids we prove
the theorem in the general case without restriction of evenness of dimension.
Our groupoid method is different from the method used by B. Hanke and T. Schick
in reduction to the case of even dimension.


title:
Recognition of Visually Perceived Compositional Human Actions by
  Multiple Spatio-Temporal Scales Recurrent Neural Networks

abstract:
  The current paper proposes a novel neural network model for recognizing
visually perceived human actions. The proposed multiple spatio-temporal scales
recurrent neural network (MSTRNN) model is derived by introducing multiple
timescale recurrent dynamics to the conventional convolutional neural network
model. One of the essential characteristics of the MSTRNN is that its
architecture imposes both spatial and temporal constraints simultaneously on
the neural activity which vary in multiple scales among different layers. As
suggested by the principle of the upward and downward causation, it is assumed
that the network can develop meaningful structures such as functional hierarchy
by taking advantage of such constraints during the course of learning. To
evaluate the characteristics of the model, the current study uses three types
of human action video dataset consisting of different types of primitive
actions and different levels of compositionality on them. The performance of
the MSTRNN in testing with these dataset is compared with the ones by other
representative deep learning models used in the field. The analysis of the
internal representation obtained through the learning with the dataset
clarifies what sorts of functional hierarchy can be developed by extracting the
essential compositionality underlying the dataset.


title:
Supermassive Black Holes with High Accretion Rates in Active Galactic
  Nuclei. VI. Velocity-resolved Reverberation Mapping of H$\beta$ Line

abstract:
  In the sixth of the series of papers reporting on a large reverberation
mapping (RM) campaign of active galactic nuclei (AGNs) with high accretion
rates, we present velocity-resolved time lags of H$\beta$ emission lines for
nine objects observed in the campaign during 2012$-$2013. In order to correct
the line-broadening caused by seeing and instruments before the analysis of
velocity-resolved RM, we adopt Richardson-Lucy deconvolution to reconstruct
their H$\beta$ profiles. The validity and effectiveness of the deconvolution
are checked out by Monte Carlo simulation. Five among the nine objects show
clear dependence of time delay on velocity. Mrk 335 and Mrk 486 show signatures
of gas inflow whereas the clouds in the broad-line regions (BLRs) of Mrk 142
and MCG +06-26-012 tend to be radial outflowing. Mrk 1044 is consistent with
the case of virialized motions. The lags of the rest four are not
velocity-resolvable. The velocity-resolved RM of super-Eddington accreting
massive black holes (SEAMBHs) shows that they have diversity of the kinematics
in their BLRs. Comparing with the AGNs with sub-Eddington accretion rates, we
do not find significant differences in the BLR kinematics of SEAMBHs.


title: Poisson Law for returns of Maps on Compact Manifolds

abstract:
  We consider invariant measures of maps on manifolds whose correlations decay
at a sufficient rate and which satisfy a geometric contraction property. We
then prove the that the limiting distribution of returns to geometric balls is
Poissonian. This does not assume an tower construction. The decay of
correlations is used to show that the independence generated results in the
Poisson distribution for returns that are sufficiently separated. A geometric
contraction property is then used to show that short return times have a
vanishing contribution to the return times distribution. We then also show that
the set of very short returns which are of a small linear order of the
logarithm of the radius of the balls has a vanishing measure. We obtain error
terms which decay polynomially in the logarithm of the radius. We also obtain a
extreme value law for such systems.


title: Real multiplication through explicit correspondences

abstract:
  We compute equations for real multiplication on the divisor classes of genus
two curves via algebraic correspondences. We do so by implementing van
Wamelen's method for computing equations for endomorphisms of Jacobians on
examples drawn from the algebraic models for Hilbert modular surfaces computed
by Elkies and Kumar. We also compute a correspondence over the universal family
for the Hilbert modular surface of discriminant 5 and use our equations to
prove a conjecture of A. Wright on dynamics over the moduli space of Riemann
surfaces.


title: Massively Multilingual Word Embeddings

abstract:
  We introduce new methods for estimating and evaluating embeddings of words in
more than fifty languages in a single shared embedding space. Our estimation
methods, multiCluster and multiCCA, use dictionaries and monolingual data; they
do not require parallel data. Our new evaluation method, multiQVEC-CCA, is
shown to correlate better than previous ones with two downstream tasks (text
categorization and parsing). We also describe a web portal for evaluation that
will facilitate further research in this area, along with open-source releases
of all our methods.


title: Generalized Surface Polaritons and their quantum spin Hall effect

abstract:
  Surface polaritons, e.g., surface plasmon polaritons, are invaluable tools in
nanophotonics. However, considerable plasmon loss narrows the application
regime of plasmonic devices. Here we reveal some general conditions for
lossless surface polaritons to emerge at the interface of a gain and a loss
media. The gain medium does not only compensate the energy loss, but also
modifies surface wave oscillation mechanisms. A new type of surface polaritons
induced by the sign switch of the imaginary part of the permittivity across the
interface is discovered. The surface polaritons exhibit spin Hall effect due to
spin-momentum locking and unique Berry phase. The spin Hall coefficient changes
the sign across the parity-time symmetric limit and becomes quantized for
perfect metal-dielectric interface and for dielectric-dielectric interface with
very large permittivity contrast, carrying opposite topological numbers. Our
study opens a new direction for manipulating light with surface polaritons in
non-Hermitian optical systems.


title: On Feature based Delaunay Triangulation for Palmprint Recognition

abstract:
  Authentication of individuals via palmprint based biometric system is
becoming very popular due to its reliability as it contains unique and stable
features. In this paper, we present a novel approach for palmprint recognition
and its representation. To extract the palm lines, local thresholding technique
Niblack binarization algorithm is adopted. The endpoints of these lines are
determined and a connection is created among them using the Delaunay
triangulation thereby generating a distinct topological structure of each
palmprint. Next, we extract different geometric as well as quantitative
features from the triangles of the Delaunay triangulation that assist in
identifying different individuals. To ensure that the proposed approach is
invariant to rotation and scaling, features were made relative to topological
and geometrical structure of the palmprint. The similarity of the two
palmprints is computed using the weighted sum approach and compared with the
k-nearest neighbor. The experimental results obtained reflect the effectiveness
of the proposed approach to discriminate between different palmprint images and
thus achieved a recognition rate of 90% over large databases.


title:
Completing electron scattering studies with the inert gas column:e - Rn
  scattering and Ionization

abstract:
  Interest in the inert or noble- gas atoms in general arises because they are
ideal as test systems for various theoretical models of electron scattering and
also since their interaction processes serve as reference for the determination
of instrumental responses in electron scattering experiments. The ionization
cross section data of ground state inert gas atoms He through Xe are considered
to be benchmark data. Our aim in this paper is to provide theoretical results
on electron scattering with Radon atoms, as it would complete the studies on
the entire inert gas column. That is possible with this particular column only,
in view of the preceding literature on He through Xe . Inert gas radon is
radioactive, and would be a difficult target for electron scattering
experiments. In the present calculations, the complications arising from
radioactivity are not considered. We provide hitherto unavailable cross
sections on atomic radon, and also provide opportunity of the comparison of
electron impact cross sections over all the inert gas targets.


title: Fantastic 4 system for NIST 2015 Language Recognition Evaluation

abstract:
  This article describes the systems jointly submitted by Institute for
Infocomm (I$^2$R), the Laboratoire d'Informatique de l'Universit\'e du Maine
(LIUM), Nanyang Technology University (NTU) and the University of Eastern
Finland (UEF) for 2015 NIST Language Recognition Evaluation (LRE). The
submitted system is a fusion of nine sub-systems based on i-vectors extracted
from different types of features. Given the i-vectors, several classifiers are
adopted for the language detection task including support vector machines
(SVM), multi-class logistic regression (MCLR), Probabilistic Linear
Discriminant Analysis (PLDA) and Deep Neural Networks (DNN).


title: On The Robustness of Price-Anticipating Kelly Mechanism

abstract:
  The price-anticipating Kelly mechanism (PAKM) is one of the most extensively
used strategies to allocate divisible resources for strategic users in
communication networks and computing systems. The users are deemed as selfish
and also benign, each of which maximizes his individual utility of the
allocated resources minus his payment to the network operator. However, in many
applications a user can use his payment to reduce the utilities of his
opponents, thus playing a misbehaving role. It remains mysterious to what
extent the misbehaving user can damage or influence the performance of benign
users and the network operator. In this work, we formulate a non-cooperative
game consisting of a finite amount of benign users and one misbehaving user.
The maliciousness of this misbehaving user is captured by his willingness to
pay to trade for unit degradation in the utilities of benign users. The network
operator allocates resources to all the users via the price-anticipating Kelly
mechanism. We present six important performance metrics with regard to the
total utility and the total net utility of benign users, and the revenue of
network operator under three different scenarios: with and without the
misbehaving user, and the maximum. We quantify the robustness of PAKM against
the misbehaving actions by deriving the upper and lower bounds of these
metrics. With new approaches, all the theoretical bounds are applicable to an
arbitrary population of benign users. Our study reveals two important insights:
i) the performance bounds are very sensitive to the misbehaving user's
willingness to pay at certain ranges; ii) the network operator acquires more
revenues in the presence of the misbehaving user which might disincentivize his
countermeasures against the misbehaving actions.


title:
Thermalization and many-body localization in systems under dynamic
  nuclear polarization

abstract:
  We study the role of dipolar interactions in the standard protocol used to
achieve dynamic nuclear polarization (DNP). In the so-called spin-temperature
regime, where the interactions establish an effective thermodynamic behavior in
the out-of-equilibrium stationary state, we provide numerical predictions for
the level of hyperpolarization. We show that nuclear spins equilibrate to the
effective spin-temperature established among the electron spins of radicals, as
expected from the quantum theory of thermalization. Moreover, we present an
analytical technique to estimate the spin temperature, and thus, the nuclear
hyperpolarization in the steady state, as a function of interaction strength
and quenched disorder. This reproduces both our numerical data and experimental
results. Our central finding is that the nuclear hyperpolarization increases
steadily upon reducing the interaction strength (by diluting the radical
density). Interestingly, the highest polarization is reached at a point where
the establishment of a spin temperature is just about to break down due to the
incipient many-body localization transition in the electron spin system.


title:
Proximal Point Algorithms for Nonsmooth Convex Optimization with Fixed
  Point Constraints

abstract:
  The problem of minimizing the sum of nonsmooth, convex objective functions
defined on a real Hilbert space over the intersection of fixed point sets of
nonexpansive mappings, onto which the projections cannot be efficiently
computed, is considered. The use of proximal point algorithms that use the
proximity operators of the objective functions and incremental optimization
techniques is proposed for solving the problem. With the focus on fixed point
approximation techniques, two algorithms are devised for solving the problem.
One blends an incremental subgradient method, which is a useful algorithm for
nonsmooth convex optimization, with a Halpern-type fixed point iteration
algorithm. The other is based on an incremental subgradient method and the
Krasnosel'ski\u\i-Mann fixed point algorithm. It is shown that any weak
sequential cluster point of the sequence generated by the Halpern-type
algorithm belongs to the solution set of the problem and that there exists a
weak sequential cluster point of the sequence generated by the
Krasnosel'ski\u\i-Mann-type algorithm, which also belongs to the solution set.
Numerical comparisons of the two proposed algorithms with existing subgradient
methods for concrete nonsmooth convex optimization show that the proposed
algorithms achieve faster convergence.


title:
Rotational Properties of the Odd-$Z$ Transfermium Nucleus $^{255}$Lr by
  a Particle-number-conserving Method in the Cranked Shell Model

abstract:
  Experimentally observed ground state band based on the $1/2^{-}[521]$ Nilsson
state and the first exited band based on the $7/2^{-}[514]$ Nilsson state in
the odd-$Z$ nucleus $^{255}$Lr are studied by the cranked shell model (CSM)
with the paring correlations treated by the particle-number-conserving (PNC)
method. This is the first time the detailed theoretical investigations being
performed on these rotational bands. Both the experimental kinematic and
dynamic moment of inertia ($\mathcal{J}^{(1)}$ and $\mathcal{J}^{(2)}$) versus
rotational frequency are reproduced quite well by the PNC-CSM calculations. By
comparing the theoretical kinematic moment of inertia $\mathcal{J}^{(1)}$ with
the experimental ones extracted from different spin assignments, the spin
$17/2^{-}\rightarrow13/2^{-}$ is assigned to the lowest-lying $196.6(5)$ keV
transition of the $1/2^{-}[521]$ band, and $15/2^{-}\rightarrow11/2^{-}$ to the
$189(1)$ keV transition of the $7/2^{-}[514]$ band, respectively. The proton
$N=7$ major shell is included in the calculations. The intruder of the high$-j$
low$-\Omega$ orbitals $1j_{15/2}$ $ (1/2^{-}[770])$ at the high spin leads to
the band-crossing at $\hbar\omega\approx0.20$ ($\hbar\omega\approx0.25$) MeV
for the $7/2^{-}[514]$ $\alpha=-1/2$ ($\alpha=+1/2$) band, and at
$\hbar\omega\approx0.175$ MeV for the $1/2^{-}[521]$ $\alpha=-1/2$ band,
respectively. Further investigations show that the band-crossing frequencies
are quadrupole deformation dependent.


title:
Probing Higgs Width and Top Quark Yukawa Coupling from $t\bar{t}H$ and
  $t\bar{t}t\bar{t}$ Productions

abstract:
  We demonstrate that four top-quark production is a powerful tool to constrain
the top Yukawa coupling. The constraint is robust in the sense that it does not
rely on the Higgs boson decay. Taking into account the projection of the
$t\bar{t}H$ production by the ATLAS collaobration, we obtain a bound on Higgs
boson width, $\Gamma_H\leq 3.1~\Gamma_H^{\rm SM}$, at the 14 TeV LHC with an
integrated luminosity of $300~{\rm fb}^{-1}$. Increasing the luminosity to
$500~{\rm fb}^{-1}$ yields $\Gamma_H\leq 2.1~\Gamma_H^{\rm SM}$.


title: Time-series spectroscopy of the pulsating eclipsing binary XX Cephei

abstract:
  Oscillating Algol-type eclipsing binaries (oEA) are very interesting objects
that have three observational features of eclipse, pulsation, and mass
transfer. Direct measurement of their masses and radii from the double-lined
radial velocity data and photometric light curves would be the most essential
for understanding their evolutionary process and for performing the
asteroseismological study. We present the physical properties of the oEA star
XX Cep from high-resolution time-series spectroscopic data. The effective
temperature of the primary star was determined to be 7,946 $\pm$ 240 K by
comparing the observed spectra and the Kurucz models. We detected the
absorption lines of the secondary star, which had never been detected in
previous studies, and obtained the radial velocities for both components. With
the published $BVRI$ light curves, we determined the absolute parameters for
the binary via Wilson-Devinney modeling. The masses and radii are $M_{1} = 2.49
\pm 0.06$ $M_\odot$, $M_{2} = 0.38 \pm 0.01$ $M_\odot$, $R_{1} = 2.27 \pm 0.02$
$R_\odot$, and $R_{2} = 2.43 \pm 0.02$ $R_\odot$, respectively. The primary
star is about $45 \%$ more massive and $60 \%$ larger than the zero-age main
sequence (ZAMS) stars with the same effective temperature. It is probably
because XX Cep has experienced a very different evolutionary process due to
mass transfer, contrasting with the normal main sequence stars. The primary
star is located inside the theoretical instability strip of $\delta$ Sct-type
stars on HR diagram. We demonstrated that XX Cep is an oEA star, consisting of
a $\delta$ Sct-type pulsating primary component and an evolved secondary
companion.


title: Broad-band linear polarization in late-type active dwarfs

abstract:
  We present recent polarimetric results of magnetically active late-type
dwarfs. The polarization in these stars is found to be wavelength dependent,
decreasing towards the longer wavelength. The average values of degree of
polarization in these active dwarfs are found to be 0.16+/-0.01, 0.080+/-0.006,
0.056+/-0.004 and 0.042+/-0.003 per cent in B, V, R, and I bands, respectively.
Present results indicate that polarization in the majority of active dwarfs are
primarily due to sum of the polarization by magnetic intensification and
scattering. However, supplementary sources of the polarization are also found
to be present in some active stars. The correlations between the degree of
polarization and various activity parameters like Rossby number, chromospheric
activity indicator and coronal activity indicator are found to be stronger in B
band and weaker in I band.


title:
YOURPRIVACYPROTECTOR, A recommender system for privacy settings in
  social networks

abstract:
  Ensuring privacy of users of social networks is probably an unsolvable
conundrum. At the same time, an informed use of the existing privacy options by
the social network participants may alleviate - or even prevent - some of the
more drastic privacy-averse incidents. Unfortunately, recent surveys show that
an average user is either not aware of these options or does not use them,
probably due to their perceived complexity. It is therefore reasonable to
believe that tools assisting users with two tasks: 1) understanding their
social net behavior in terms of their privacy settings and broad privacy
categories, and 2)recommending reasonable privacy options, will be a valuable
tool for everyday privacy practice in a social network context. This paper
presents YourPrivacyProtector, a recommender system that shows how simple
machine learning techniques may provide useful assistance in these two tasks to
Facebook users. We support our claim with empirical results of application of
YourPrivacyProtector to two groups of Facebook users.


title:
On the measure-theoretic entropy and topological pressure of free
  semigroup actions(to appear in ETDS)

abstract:
  In this paper, we introduce the notions of topological pressure and
measure-theoretic entropy for a free semigroup action. Suppose that a free
semigroup acts on a compact metric space by continuous self-maps. To this
action, we assign a skew-product transformation whose fiber topological
pressure is taken to be the topological pressure of the initial action. Some
properties of these two notions are given, and then we give two main results.
One is the relationship between the topological pressure of the skew-product
transformation and the topological pressure of the free semigroup action, the
other is the partial variational principle about the topological pressure.
Moreover, we apply this partial variational principle to study the
measure-theoretic entropy and the topological entropy of finite affine
transformations on a metrizable group.


title: Shi-type estimates of the Ricci flow based on Ricci curvature

abstract:
  We construct a uniform local bound of curvature operator from local bounds of
Ricci curvature and injectivity radius among all $n$-dimensional Ricci flows.
Thus new compactness theorems for the Ricci flow and Ricci solitons are
derived. In particular, we show that every Ricci flow with $|Ric|\leq K$ must
satisfy $|Rm|\leq Ct^{-1}$ for all $t\in (0,T]$, where $C$ depends only on the
dimension $n$ and $T$ depends on $K$ and the injectivity radius $inj_{g(t)}$.
  In the second part of this paper, we discuss the behavior of Ricci curvature
and its derivative when the injectivity radius is thoroughly unknown. In
particular, another Shi-type estimate for Ricci curvature is derived when the
derivative of Ricci curvature is controlled by the derivative of scalar
curvature.


title: Automatic and Quantitative evaluation of attribute discovery methods

abstract:
  Many automatic attribute discovery methods have been developed to extract a
set of visual attributes from images for various tasks. However, despite good
performance in some image classification tasks, it is difficult to evaluate
whether these methods discover meaningful attributes and which one is the best
to find the attributes for image descriptions. An intuitive way to evaluate
this is to manually verify whether consistent identifiable visual concepts
exist to distinguish between positive and negative images of an attribute. This
manual checking is tedious, labor intensive and expensive and it is very hard
to get quantitative comparisons between different methods. In this work, we
tackle this problem by proposing an attribute meaningfulness metric, that can
perform automatic evaluation on the meaningfulness of attribute sets as well as
achieving quantitative comparisons. We apply our proposed metric to recent
automatic attribute discovery methods and popular hashing methods on three
attribute datasets. A user study is also conducted to validate the
effectiveness of the metric. In our evaluation, we gleaned some insights that
could be beneficial in developing automatic attribute discovery methods to
generate meaningful attributes. To the best of our knowledge, this is the first
work to quantitatively measure the semantic content of automatically discovered
attributes.


title:
The cosmic evolution of massive black holes in the Horizon-AGN
  simulation

abstract:
  We analyse the demographics of black holes (BHs) in the large-volume
cosmological hydrodynamical simulation Horizon-AGN. This simulation
statistically models how much gas is accreted onto BHs, traces the energy
deposited into their environment and, consequently, the back-reaction of the
ambient medium on BH growth. The synthetic BHs reproduce a variety of
observational constraints such as the redshift evolution of the BH mass density
and the mass function. Strong self-regulation via AGN feedback, weak supernova
feedback, and unresolved internal processes result in a tight BH-galaxy mass
correlation. Starting at z~2, tidal stripping creates a small population of BHs
over-massive with respect to the halo. The fraction of galaxies hosting a
central BH or an AGN increases with stellar mass. The AGN fraction agrees
better with multi-wavelength studies, than single-wavelength ones, unless
obscuration is taken into account. The most massive halos present BH
multiplicity, with additional BHs gained by ongoing or past mergers. In some
cases, both a central and an off-centre AGN shine concurrently, producing a
dual AGN. This dual AGN population dwindles with decreasing redshift, as found
in observations. Specific accretion rate and Eddington ratio distributions are
in good agreement with observational estimates. The BH population is dominated
in turn by fast, slow, and very slow accretors, with transitions occurring at
z=3 and z=2 respectively.


title: Prediction of weakly locally stationary processes by auto-regression

abstract:
  In this contribution we introduce weakly locally stationary time series
through the local approximation of the non-stationary covariance structure by a
stationary one. This allows us to define autoregression coefficients in a
non-stationary context, which, in the particular case of a locally stationary
Time Varying Autoregressive (TVAR) process, coincide with the generating
coefficients. We provide and study an estimator of the time varying
autoregression coefficients in a general setting. The proposed estimator of
these coefficients enjoys an optimal minimax convergence rate under limited
smoothness conditions. In a second step, using a bias reduction technique, we
derive a minimax-rate estimator for arbitrarily smooth time-evolving
coefficients, which outperforms the previous one for large data sets. In turn,
for TVAR processes, the predictor derived from the estimator exhibits an
optimal minimax prediction rate.


title:
On $5$-manifolds with free fundamental group and simple boundary links
  in $S^5$

abstract:
  We classify compact oriented $5$-manifolds with free fundamental group and
$\pi_{2}$ a torsion free abelian group in terms of the second homotopy group
considered as $\pi_1$-module, the cup product on the second cohomology of the
universal covering, and the second Stiefel-Whitney class of the universal
covering. We apply this to the classification of simple boundary links of
$3$-spheres in $S^5$. Using this we give a complete algebraic picture of closed
$5$-manifolds with free fundamental group and trivial second homology group.


title: Immersive Augmented Reality Training for Complex Manufacturing Scenarios

abstract:
  In the complex manufacturing sector a considerable amount of resources are
focused on developing new skills and training workers. In that context,
increasing the effectiveness of those processes and reducing the investment
required is an outstanding issue. In this paper we present an experiment that
shows how modern Human Computer Interaction (HCI) metaphors such as
collaborative mixed-reality can be used to transmit procedural knowledge and
could eventually replace other forms of face-to-face training. We implement a
real-time Immersive Augmented Reality (IAR) setup with see-through cameras that
allows for collaborative interactions that can simulate conventional forms of
training. The obtained results indicate that people who took the IAR training
achieved the same performance than people in the conventional face-to-face
training condition. These results, their implications for future training and
the use of HCI paradigms in this context are discussed in this paper.


title: Instabilities of Spin-Liquid States in a Quantum Kagome Antiferromagnet

abstract:
  The emergent behavior of spin liquids that are born out of geometrical
frustration makes them an intriguing state of matter. We show that in the
quantum kagome antiferromagnet ZnCu$_3$(OH)$_6$SO$_4$ several different
correlated, yet fluctuating states exist. By combining complementary
local-probe techniques with neutron scattering, we discover a crossover from a
critical regime into a gapless spin-liquid phase with decreasing temperature.
An additional unconventional instability of the latter phase leads to a second,
distinct spin-liquid state that is stabilized at the lowest temperatures. We
advance such complex behavior as a feature common to different frustrated
quantum magnets.


title:
Instantaneous blow-up versus global well-posedness and asymptotic
  behavior for linear pseudoparabolic equations

abstract:
  We study linear pseudoparabolic equations with unbounded and time-dependent
coefficients. We solve the case which has remained open in several recent
studies of pseudoparabolic equations with unbounded and time-dependent
coefficients. In this work we get a sharp condition for the existence or
non-existence of solutions. Conditions on the initial function and coefficient
are provided so that every nontrivial positive solution blows up
instantaneously. When the coefficient and the initial function do not grow too
rapidly, we establish the existence and uniqueness of global solutions, for
both time-independent and time-dependent potentials. This is done via the
analysis of the Bessel convolution multiplication operators. Asymptotic
behavior and comparison principles are also established. The global
well-posedness results can be extended to the equation with convection.


title:
Investigating Reliability Aspects of Memristor based RRAM with Reference
  to Write Voltage and Frequency

abstract:
  In this paper, we report the effect of write voltage and frequency on
memristor based Resistive Random Access Memory (RRAM). The above said
parameters have been investigated on the linear drift model of memristor. With
a variation of write voltage from 0.2V to 1.2V and a subsequent frequency
modulation from 1, 2, 4, 10, 100 and 200 Hz the corresponding effects on memory
window, Low Resistance State (LRS) and High Resistance State (HRS) have been
reported. Thus the lifetime ({\tau}) reliability analysis of memristor based
RRAM is carried out using above results. It is found that, the HRS is
independent of write voltage, whereas LRS shows dependency on write voltage and
frequency. The simulation results showcase that the memristor possess higher
memory window and lifetime ({\tau}) in the higher voltage with lower frequency
region, which has been attributed to the fewer data losses in the memory
architecture.


title: A bilinear Rubio de Francia inequality for arbitrary squares

abstract:
  We prove the boundedness of a smooth bilinear Rubio de Francia operator
associated with an arbitrary collection of squares (with sides parallel to the
axes) in the frequency plane\[\left(f, g \right)\mapsto \left( \sum\_{\omega
\in \Omega}\left| \int\_{\mathbb{R}^2} \hat{f}(\xi) \hat{g}(\eta)
\Phi\_{\omega}(\xi, \eta) e^{2 \pi i x\left(\xi+\eta \right)} d \xi d
\eta\right|^r \right)^{1/r},\] provided $r\textgreater{}2$. More exactly, we
show that the above operator maps $L^p \times L^q \to L^s$ whenever $p, q, s'$
are in the "local $L^{r'}$" range, i.e. $\displaystyle
\frac{1}{p}+\frac{1}{q}+\frac{1}{s'}=1$, $\displaystyle0 \leq \frac{1}{p},
\frac{1}{q} \textless{}\frac{1}{r'}$, and
$\displaystyle\frac{1}{s'}\textless{}\frac{1}{r'}$. Note that we allow for
negative values of $s'$, which correspond to quasi-Banach spaces $L^s$.


title:
Trajectory Generation for Quadrotor Based Systems using Numerical
  Optimal Control

abstract:
  The recent works on quadrotor have focused on more and more challenging tasks
on increasingly complex systems. Systems are often augmented with slung loads,
inverted pendulums or arms, and accomplish complex tasks such as going through
a window, grasping, throwing or catching. Usually, controllers are designed to
accomplish a specific task on a specific system using analytic solutions, so
each application needs long preparations. On the other hand, the direct
multiple shooting approach is able to solve complex problems without any
analytic development, by using on-the-shelf optimization solver. In this paper,
we show that this approach is able to solve a wide range of problems relevant
to quadrotor systems, from on-line trajectory generation for quadrotors, to
going through a window for a quadrotor-and-pendulum system, through
manipulation tasks for a aerial manipulator.


title:
RPYS i/o: A web-based tool for the historiography and visualization of
  citation classics, sleeping beauties, and research fronts

abstract:
  Reference Publication Year Spectroscopy (RPYS) and Multi-RPYS provide
algorithmic approaches to reconstructing the intellectual histories of
scientific fields. With this brief communication, we describe a technical
advancement for developing research historiographies by introducing RPYS i/o,
an online tool for performing standard RPYS and Multi-RPYS analyses
interactively (at http://comins.leydesdorff.net/). The tool enables users to
explore seminal works underlying a research field and to plot the influence of
these seminal works over time. This suite of visualizations offers the
potential to analyze and visualize the myriad of temporal dynamics of
scientific influence, such as citation classics, sleeping beauties, and the
dynamics of research fronts. We demonstrate the features of the tool by
analyzing--as an example--the references in documents published in the journal
Philosophy of Science.


title: Greedy algorithms for prediction

abstract:
  In many prediction problems, it is not uncommon that the number of variables
used to construct a forecast is of the same order of magnitude as the sample
size, if not larger. We then face the problem of constructing a prediction in
the presence of potentially large estimation error. Control of the estimation
error is either achieved by selecting variables or combining all the variables
in some special way. This paper considers greedy algorithms to solve this
problem. It is shown that the resulting estimators are consistent under weak
conditions. In particular, the derived rates of convergence are either minimax
or improve on the ones given in the literature allowing for dependence and
unbounded regressors. Some versions of the algorithms provide fast solution to
problems such as Lasso.


title: A Generalized Axis Theorem for Cube Complexes

abstract:
  We consider a finitely generated virtually abelian group $G$ acting properly
and without inversions on a CAT(0) cube complex $X$. We prove that $G$
stabilizes a finite dimensional CAT(0) subcomplex $Y \subseteq X$ that is
isometrically embedded in the combinatorial metric. Moreover, we show that $Y$
is a product of finitely many quasilines. The result represents a higher
dimensional generalization of Haglund's axis theorem.


title: Emission redistribution from a quantum dot-bowtie nanoantenna

abstract:
  We present a combined experimental and simulation study of a single
self-assembled InGaAs quantum dot coupled to a nearby ($\sim 25nm$) plasmonic
antenna. Micro-photoluminescence spectroscopy shows a $\sim 2.4\times$ increase
of intensity, which is attributed to spatial far-field redistribution of the
emission from the quantum dot-antenna system. Power-dependent studies show
similar saturation powers of $2.5\mu W$ for both coupled and uncoupled quantum
dot emission in polarization-resolved measurements. Moreover, time-resolved
spectroscopy reveals the absence of Purcell-enhancement of the quantum dot
coupled to the antenna as compared to an uncoupled dot, yielding comparable
exciton lifetimes of $\tau\sim0.5ns$. This observation is supported by
numerical simulations, suggesting only minor Purcell-effects of $<2\times$ for
emitter-antenna separations $>25nm$. The observed increased emission from a
coupled quantum dot-plasmonic antenna system is found to be in good qualitative
agreement with numerical simulations and will lead to a better understanding of
light-matter-coupling in such novel semiconductor-plasmonic hybrid systems


title: On the Chern numbers for pseudo-free circle actions

abstract:
  Let $(M,\psi)$ be a $(2n+1)$-dimensional oriented closed manifold equipped
with a pseudo-free $S^1$-action $\psi : S^1 \times M \rightarrow M$. We first
define a \textit{local data} $\mathcal{L}(M,\psi)$ of the action $\psi$ which
consists of pairs $(C, (p(C) ; \overrightarrow{q}(C)))$ where $C$ is an
exceptional orbit, $p(C)$ is the order of isotropy subgroup of $C$, and
$\overrightarrow{q}(C) \in (\mathbb{Z}_{p(C)}^{\times})^n$ is a vector whose
entries are the weights of the slice representation of $C$. In this paper, we
give an explicit formula of the Chern number $\langle c_1(E)^n, [M/S^1]
\rangle$ modulo $\mathbb{Z}$ in terms of the local data, where $E = M
\times_{S^1} \mathbb{C}$ is the associated complex line orbibundle over
$M/S^1$. Also, we illustrate several applications to various problems arising
in equivariant symplectic topology.


title: Exchangeable exogenous shock models

abstract:
  We characterize a comprehensive family of $d$-variate exogenous shock models.
Analytically, we consider a family of multivariate distribution functions that
arises from ordering, idiosyncratically distorting, and finally multiplying the
arguments. Necessary and sufficient conditions on the involved distortions to
yield a multivariate distribution function are given. Probabilistically, the
attainable set of distribution functions corresponds to a large class of
exchangeable exogenous shock models. Besides, the vector of exceedance times of
an increasing additive stochastic process across independent exponential
trigger variables is shown to constitute an interesting subclass of the
considered distributions and yields a second probabilistic model. The
alternative construction is illustrated in terms of two examples.


title:
"Almost-stable" matchings in the Hospitals / Residents problem with
  Couples

abstract:
  The Hospitals / Residents problem with Couples (HRC) models the allocation of
intending junior doctors to hospitals where couples are allowed to submit joint
preference lists over pairs of (typically geographically close) hospitals. It
is known that a stable matching need not exist, so we consider MIN BP HRC, the
problem of finding a matching that admits the minimum number of blocking pairs
(i.e., is "as stable as possible"). We show that this problem is NP-hard and
difficult to approximate even in the highly restricted case that each couple
finds only one hospital pair acceptable. However if we further assume that the
preference list of each single resident and hospital is of length at most 2, we
give a polynomial-time algorithm for this case. We then present the first
Integer Programming (IP) and Constraint Programming (CP) models for MIN BP HRC.
Finally, we discuss an empirical evaluation of these models applied to
randomly-generated instances of MIN BP HRC. We find that on average, the CP
model is about 1.15 times faster than the IP model, and when presolving is
applied to the CP model, it is on average 8.14 times faster. We further observe
that the number of blocking pairs admitted by a solution is very small, i.e.,
usually at most 1, and never more than 2, for the (28,000) instances
considered.


title:
Surface plasmon resonance spectroscopy of single bowtie nano-antennas
  using a differential reflectivity method

abstract:
  We report on the structural and optical properties of individual bowtie
nanoantennas both on glass and semiconducting GaAs substrates. The antennas on
glass (GaAs) are shown to be of excellent quality and high uniformity reflected
by narrow size distributions with standard deviations for the triangle and gap
size of $\sigma_s^{glass}=4.5nm$ ($\sigma_s^{GaAs}=2.6nm$) and
$\sigma_g^{glass}=5.4nm$ ($\sigma_g^{GaAs}=3.8nm$), respectively. The
corresponding optical properties of individual nanoantennas studied by
differential reflection spectroscopy show a strong reduction of the localised
surface plasmon polariton resonance linewidth from $0.21eV$ to $0.07eV$ upon
reducing the antenna size from $150nm$ to $100nm$. This is attributed to the
absence of inhomogeneous broadening as compared to optical measurements on
nanoantenna ensembles. The inter-particle coupling of an individual bowtie
nanoantenna, which gives rise to strongly localised and enhanced
electromagnetic hotspots, is demonstrated using polarization-resolved
spectroscopy, yielding a large degree of linear polarization of
$\rho_{max}\sim80\%$. The combination of highly reproducible nanofabrication
and fast, non-destructive and non-contaminating optical spectroscopy paves the
route towards future semiconductor-based nano-plasmonic circuits, consisting of
multiple photonic and plasmonic entities.


title:
Distributed Scenario-Based Optimization for Asset Management in a
  Hierarchical Decision Making Environment

abstract:
  Asset management attempts to keep the power system in working conditions. It
requires much coordination between multiple entities and long term planning
often months in advance. In this work we introduce a mid-term asset management
formulation as a stochastic optimization problem, that includes three
hierarchical layers of decision making, namely the mid-term, short-term and
real-time. We devise a tractable scenario approximation technique for
efficiently assessing the complex implications a maintenance schedule inflicts
on a power system. This is done using efficient Monte-Carlo simulations that
trade-off between accuracy and tractability. We then present our implementation
of a distributed scenario-based optimization algorithm for solving our
formulation, and use an updated PJM 5-bus system to show a solution that is
cheaper than other maintenance heuristics that are likely to be considered by
TSOs.


title: Lifetime-Based Memory Management for Distributed Data Processing Systems

abstract:
  In-memory caching of intermediate data and eager combining of data in shuffle
buffers have been shown to be very effective in minimizing the re-computation
and I/O cost in distributed data processing systems like Spark and Flink.
However, it has also been widely reported that these techniques would create a
large amount of long-living data objects in the heap, which may quickly
saturate the garbage collector, especially when handling a large dataset, and
hence would limit the scalability of the system. To eliminate this problem, we
propose a lifetime-based memory management framework, which, by automatically
analyzing the user-defined functions and data types, obtains the expected
lifetime of the data objects, and then allocates and releases memory space
accordingly to minimize the garbage collection overhead. In particular, we
present Deca, a concrete implementation of our proposal on top of Spark, which
transparently decomposes and groups objects with similar lifetimes into byte
arrays and releases their space altogether when their lifetimes come to an end.
An extensive experimental study using both synthetic and real datasets shows
that, in comparing to Spark, Deca is able to 1) reduce the garbage collection
time by up to 99.9%, 2) to achieve up to 22.7x speed up in terms of execution
time in cases without data spilling and 41.6x speedup in cases with data
spilling, and 3) to consume up to 46.6% less memory.


title: Multiple Wavelet Coherency Analysis and Forecasting of Metal Prices

abstract:
  The assessment of co-movement among metals is crucial to better understand
the behaviors of the metal prices and the interactions with others that affect
the changes in prices. In this study, both Wavelet Analysis and VARMA (Vector
Autoregressive Moving Average) models are utilized. First, Multiple Wavelet
Coherence (MWC), where Wavelet Analysis is needed, is utilized to determine
dynamic correlation time interval and scales. VARMA is then used for
forecasting which results in reduced errors.
  The daily prices of steel, aluminium, copper and zinc between 10.05.2010 and
29.05.2014 are analyzed via wavelet analysis to highlight the interactions.
Results uncover interesting dynamics between mentioned metals in the
time-frequency space. VARMA (1,1) model forecasting is carried out considering
the daily prices between 14.11.2011 and 16.11.2012 where the interactions are
quite high and prediction errors are found quite limited with respect to
ARMA(1.1). It is shown that dynamic co-movement detection via four variables
wavelet coherency analysis in the determination of VARMA time interval enables
to improve forecasting power of ARMA by decreasing forecasting errors.


title:
Magnetic order and spin excitations in the Kitaev--Heisenberg model on
  the honeycomb lattice

abstract:
  We consider the quasi-two-dimensional pseudo-spin-1/2 Kitaev - Heisenberg
model proposed for A2IrO3 (A=Li, Na) compounds. The spin-wave excitation
spectrum, the sublattice magnetization, and the transition temperatures are
calculated in the random phase approximation (RPA) for four different ordered
phases, observed in the parameter space of the model: antiferomagnetic, stripe,
ferromagnetic, and zigzag phases. The N\'{e}el temperature and temperature
dependence of the sublattice magnetization are compared with the experimental
data on Na2IrO3.


title:
The method of uniqueness and the optical conductivity of graphene: new
  application of a powerful technique for multi-loop calculations

abstract:
  We review the method of uniqueness which is a powerful technique for
multi-loop calculations in higher dimensional theories with conformal symmetry.
We use the method in momentum space and show that it allows a very transparent
evaluation of a two-loop massless propagator Feynman diagram with a non-integer
index on the central line. The result is applied to the computation of the
optical conductivity of graphene at the infra-red Lorentz invariant fixed
point. The effect of counter-terms is analysed. A brief comparison with the
non-relativistic case is included.


title: Winning Cores in Parity Games

abstract:
  We introduce the novel notion of winning cores in parity games and develop a
deterministic polynomial-time under-approximation algorithm for solving parity
games based on winning core approximation. Underlying this algorithm are a
number properties about winning cores which are interesting in their own right.
In particular, we show that the winning core and the winning region for a
player in a parity game are equivalently empty. Moreover, the winning core
contains all fatal attractors but is not necessarily a dominion itself.
Experimental results are very positive both with respect to quality of
approximation and running time. It outperforms existing state-of-the-art
algorithms significantly on most benchmarks.


title: H\"older regularity of generic manifold

abstract:
  In this paper we study H\"older continuity of the pluricomplex Green function
with logarithmic growth at infinity of a smooth generic submanifold of $\C^n$.
In particular we prove that the pluricomplex Green function of any $C^2$-smooth
generic compact submanifold of $\C^n$ (without boundary) is Lipschitz
continuous in $\C^n$.


title:
The dust environment of comet 67P/Churyumov-Gerasimenko from Rosetta
  OSIRIS and VLT observations in the 4.5 to 2.9 au heliocentric distance range
  inbound

abstract:
  The ESA Rosetta spacecraft, currently orbiting around comet 67P, has already
provided in situ measurements of the dust grain properties from several
instruments, particularly OSIRIS and GIADA. We propose adding value to those
measurements by combining them with ground-based observations of the dust tail
to monitor the overall, time-dependent dust-production rate and size
distribution. To constrain the dust grain properties, we take Rosetta OSIRIS
and GIADA results into account, and combine OSIRIS data during the approach
phase (from late April to early June 2014) with a large data set of
ground-based images that were acquired with the ESO Very Large Telescope (VLT)
from February to November 2014. A Monte Carlo dust tail code has been applied
to retrieve the dust parameters. Key properties of the grains (density,
velocity, and size distribution) were obtained from Rosetta observations: these
parameters were used as input of the code to considerably reduce the number of
free parameters. In this way, the overall dust mass-loss rate and its
dependence on the heliocentric distance could be obtained accurately. The dust
parameters derived from the inner coma measurements by OSIRIS and GIADA and
from distant imaging using VLT data are consistent, except for the power index
of the size-distribution function, which is $\alpha$=--3, instead of
$\alpha$=--2, for grains smaller than 1 mm. This is possibly linked to the
presence of fluffy aggregates in the coma. The onset of cometary activity
occurs at approximately 4.3 au, with a dust production rate of 0.5 kg/s,
increasing up to 15 kg/s at 2.9 au. This implies a dust-to-gas mass ratio
varying between 3.8 and 6.5 for the best-fit model when combined with
water-production rates from the MIRO experiment.


title:
Infalling clouds on to supermassive black hole binaries - II. Binary
  evolution and the final parsec problem

abstract:
  The formation of massive black hole binaries (MBHBs) is an unavoidable
outcome of galaxy evolution via successive mergers. However, the mechanism that
drives their orbital evolution from parsec separations down to the
gravitational wave (GW) dominated regime is poorly understood, and their final
fate is still unclear. If such binaries are embedded in gas-rich and turbulent
environments, as observed in remnants of galaxy mergers, the interaction with
gas clumps (such as molecular clouds) may efficiently drive their orbital
evolution. Using numerical simulations, we test this hypothesis by studying the
dynamical evolution of an equal-mass, circular MBHB accreting infalling
molecular clouds. We investigate different orbital configurations, modelling a
total of 13 systems to explore different possible impact parameters and
relative inclinations of the cloud-binary encounter. We focus our study on the
prompt, transient phase during the first few orbits when the dynamical
evolution of the binary is fastest, finding that this evolution is dominated by
the exchange of angular momentum through gas capture by the individual black
holes and accretion. Building on these results, we construct a simple model for
evolving a MBHB interacting with a sequence of clouds, which are randomly drawn
from reasonable populations with different levels of anisotropy in their
angular momenta distributions. We show that the binary efficiently evolves down
to the GW emission regime within a few hundred million years, overcoming the
'final parsec' problem regardless of the stellar distribution.


title: Origin of the chaotic motion of the Saturnian satellite Atlas

abstract:
  We revisit the dynamics of Atlas. Using Cassini ISS astrometric observations
spanning February 2004 to August 2013, Cooper et al. (2015) found evidence that
Atlas is currently perturbed by both a 54:53 corotation eccentricity resonance
(CER) and a 54:53 Lindblad eccentricity resonance (LER) with Prometheus. They
demonstrated that the orbit of Atlas is chaotic, with a Lyapunov time of order
10 years, as a direct consequence of the coupled resonant interaction (CER/LER)
with Prometheus. Here we investigate the interactions between the two
resonances using the CoraLin analytical model (El Moutamid et al. 2014),
showing that the chaotic zone fills almost all the corotation sites occupied by
the satellite's orbit. Four 70:67 apse-type mean motion resonances with Pandora
are also overlapping, but these resonances have a much weaker effect. Frequency
analysis allows us to highlight the coupling between the 54:53 resonances, and
confirms that a simplified system including the perturbations due to Prometheus
and Saturn's oblateness only captures the essential features of the dynamics.


title:
Variation of Spectral and Timing Properties in the Extended Burst Tails
  from the Magnetar 4U 0142+61

abstract:
  Extended emission episodes with intensity above the pre-burst level are
observed following magnetar bursts from a number of soft gamma repeaters (SGRs)
and anomalous X-ray pulsars (AXPs). Such extended tail emission were observed
subsequent to two events detected from AXP 4U 0142+61. We investigated in
detail the evolution of spectral and temporal properties during these two tail
segments using RXTE/PCA observations, and report distinct variations both in
the spectral and temporal behavior throughout the tails. In particular, sudden
enhancement of pulsation amplitude in conjunction with bursts, and smooth
decline of X-ray emission (cooling) during the tail were observed in both
cases. We suggest that an inefficiently radiating trapped fireball formed
during the burst, which can heat up the stellar surface, is able to explain the
tail properties and its energetics. We also present the episodic detection of
absorption and emission features during tails. One possible mechanism that has
been proposed to give rise to such spectral lines is the proton/ion cyclotron
resonance process which has been suggested to offer a valuable tool in probing
the complex magnetic field of magnetars.


title: Voltage stress minimization by optimal reactive power control

abstract:
  A standard operational requirement in power systems is that the voltage
magnitudes lie within prespecified bounds. Conventional engineering wisdom
suggests that such a tightly-regulated profile, imposed for system design
purposes and good operation of the network, should also guarantee a secure
system, operating far from static bifurcation instabilities such as voltage
collapse. In general however, these two objectives are distinct and must be
separately enforced. We formulate an optimization problem which maximizes the
distance to voltage collapse through injections of reactive power, subject to
power flow and operational voltage constraints. By exploiting a linear
approximation of the power flow equations we arrive at a convex reformulation
which can be efficiently solved for the optimal injections. We also address the
planning problem of allocating the resources by recasting our problem in a
sparsity-promoting framework that allows us to choose a desired trade-off
between optimality of injections and the number of required actuators. Finally,
we present a distributed algorithm to solve the optimization problem, showing
that it can be implemented on-line as a feedback controller. We illustrate the
performance of our results with the IEEE30 bus network.


title: Threshold games and cooperation on multiplayer graphs

abstract:
  Objective: The study investigates the effect on cooperation in multiplayer
games, when the population from which all individuals are drawn is structured -
i.e. when a given individual is only competing with a small subset of the
entire population.
  Method: To optimize the focus on multiplayer effects, a class of games were
chosen for which the payoff depends nonlinearly on the number of cooperators -
this ensures that the game cannot be represented as a sum of pair-wise
interactions, and increases the likelihood of observing behaviour different
from that seen in two-player games. The chosen class of games are named
"threshold games", and are defined by a threshold, $M > 0$, which describes the
minimal number of cooperators in a given match required for all the
participants to receive a benefit. The model was studied primarily through
numerical simulations of large populations of individuals, each with
interaction neighbourhoods described by various classes of networks.
  Results: When comparing the level of cooperation in a structured population
to the mean-field model, we find that most types of structure lead to a
decrease in cooperation. This is both interesting and novel, simply due to the
generality and breadth of relevance of the model - it is likely that any model
with similar payoff structure exhibits related behaviour.
  More importantly, we find that the details of the behaviour depends to a
large extent on the size of the immediate neighbourhoods of the individuals, as
dictated by the network structure. In effect, the players behave as if they are
part of a much smaller, fully mixed, population, which we suggest an expression
for.


title: Wayfinding and cognitive maps for pedestrian models

abstract:
  Usually, routing models in pedestrian dynamics assume that agents have
fulfilled and global knowledge about the building's structure. However, they
neglect the fact that pedestrians possess no or only parts of information about
their position relative to final exits and possible routes leading to them. To
get a more realistic description we introduce the systematics of gathering and
using spatial knowledge. A new wayfinding model for pedestrian dynamics is
proposed. The model defines for every pedestrian an individual knowledge
representation implying inaccuracies and uncertainties. In addition,
knowledge-driven search strategies are introduced. The presented concept is
tested on a fictive example scenario.


title:
Proper Weak Regular Splitting and its Application to Convergence of
  Alternating Iterations

abstract:
  The theory of matrix splitting is a useful tool for finding solution of
rectangular linear system of equations, iteratively. The purpose of this paper
is two-fold. Firstly, we revisit theory of weak regular splittings for
rectangular matrices. Secondly, we propose an alternating iterative method for
solving rectangular linear systems by using the Moore-Penrose inverse and
discuss its convergence theory, by extending the work of Benzi and Szyld
Numererische Mathematik 76 (1997) 309-321; MR1452511]. Furthermore, a
comparison result is obtained which insures faster convergence rate of the
proposed alternating iterative scheme.


title:
Combining fast inertial dynamics for convex optimization with Tikhonov
  regularization

abstract:
  In a Hilbert space setting $\mathcal H$, we study the convergence properties
as $t \to + \infty$ of the trajectories of the second-order differential
equation \begin{equation*}
  \mbox{(AVD)}_{\alpha, \epsilon} \quad \quad \ddot{x}(t) + \frac{\alpha}{t}
\dot{x}(t) + \nabla \Phi (x(t)) + \epsilon (t) x(t) =0, \end{equation*} where
$\nabla\Phi$ is the gradient of a convex continuously differentiable function
$\Phi: \mathcal H \to \mathbb R$, $\alpha$ is a positive parameter, and
$\epsilon (t) x(t)$ is a Tikhonov regularization term, with $\lim_{t \to
\infty}\epsilon (t) =0$. In this damped inertial system, the damping
coefficient $\frac{\alpha}{t}$ vanishes asymptotically, but not too quickly, a
key property to obtain rapid convergence of the values. In the case $\epsilon
(\cdot) \equiv 0$, this dynamic has been highlighted recently by Su, Boyd, and
Cand\`es as a continuous version of the Nesterov accelerated method. Depending
on the speed of convergence of $\epsilon (t)$ to zero, we analyze the
convergence properties of the trajectories of $\mbox{(AVD)}_{\alpha,
\epsilon}$. We obtain results ranging from the rapid convergence of $\Phi
(x(t))$ to $\min \Phi$ when $\epsilon (t)$ decreases rapidly to zero, up to the
strong ergodic convergence of the trajectories to the element of minimal norm
of the set of minimizers of $\Phi$, when $\epsilon (t)$ tends slowly to zero.


title: Commissioning of a dual-phase xenon TPC at Nikhef

abstract:
  A dual-phase xenon time-projection chamber was built at Nikhef in Amsterdam
as a direct dark matter detection R&D facility. In this paper, the setup is
presented and the first results from a calibration with a $^{22}$Na gamma-ray
source are presented. The results show an average light yield of (5.6 $\pm$
0.3) photoelectrons/keV (calculated to 122 keV and zero field) and an electron
lifetime of (429 $\pm$ 26) $\mu$s. The best energy resolution $\sigma_E/E$ is
(5.8 $\pm$ 0.2)% at an energy of 511 keV. This was achieved using a combination
of the scintillation and the ionization signals. A photomultiplier tube gain
calibration technique, based on the electroluminescence signals occurring from
isolated electrons, is presented and its advantages and limitations are
discussed.


title:
SALT long-slit spectroscopy of HE 0435-4312: fast displacement in the Mg
  II emission line

abstract:
  The Mg II emission line is visible in the optical band for intermediate
redshift quasars (0.4 < z < 1.6) and it is thus an extremely important tool to
measure the black hole mass and to understand the structure of the Broad Line
Region. We aim to determine the substructure and the variability of the Mg II
line with the aim to identify which part of the line comes from a medium in
Keplerian motion. Using the Southern African Large Telescope (SALT) with the
Robert Stobie Spectrograph (RSS) we performed ten spectroscopic observations of
quasar HE 0435-4312 (z = 1.2231) over a period of three years (Dec 23/24, 2012
to Dec 7/8, 2015). Both the Mg II line and the Fe II pseudo-continuum increase
with time. We clearly detect the systematic shift of the Mg II line with
respect to the Fe II over the years, corresponding to the acceleration of 104
pm 14 km/s/year in the quasar rest frame. The Mg II line shape is clearly
non-Gaussian but single-component, and the increase in line equivalent width
and line shift is not accompanied with significant evolution of the line shape.
We analyse the conditions in the Mg II and Fe II formation region and we note
that the very large difference in the covering factor and the turbulent
velocity also support the conclusion that the two regions are spatially
separated. The measured acceleration of the line systematic shift is too large
to connect it with the orbital motion at a distance of the Broad Line Region
(BLR) in this source. It may imply a precessing inner disk illuminating the
BLR. Further monitoring is still needed to better constrain the variability
mechanism.


title: Quantum transport in ferromagnetic graphene: Role of Berry curvature

abstract:
  The magnetic effects in ferromagnetic graphene basically depend on the
principle of exchange interaction when ferromagntism is induced by depositing
an insulator layer on graphene. Here we deal with the consequences of
non-uniformity in the exchange coupling strength of the ferromagnetic graphene.
We discuss how the in- homogeneity in the coordinate and momentum of the
exchange vector field can provide interesting results in the conductivity
analysis of the ferromagnetic graphene. Our analysis is based on the Kubo
formalism of quantum transport.


title:
On Globally Diffeomorphic Polynomial Maps via Newton Polytopes and
  Circuit Numbers

abstract:
  In this article we analyze the global diffeomorphism property of polynomial
maps $F:\mathbb{R}^n\rightarrow\mathbb{R}^n$ by studying the properties of the
Newton polytopes at infinity corresponding to the sum of squares polynomials
$\|F\|_2^2$. This allows us to identify a class of polynomial maps $F$ for
which their global diffeomorphism property on $\mathbb{R}^n$ is equivalent to
their Jacobian determinant $\text{det }JF$ vanishing nowhere on $\mathbb{R}^n$.
In other words, we identify a class of polynomial maps for which the Real
Jacobian Conjecture, which was proven to be false in general, still holds.


title:
Reply to "Comment on `Breakdown of the expansion of finite-size
  corrections to the hydrogen Lamb shift in moments of charge distribution'"

abstract:
  To comply with the critique of the Comment [J. Arrington, arXiv:1602.01461],
we consider another modification of the proton electric form factor, which
resolves the "proton-radius puzzle". The proposed modification satisfies all
the consistency criteria put forward in the Comment, and yet has a similar
impact on the puzzle as that of the original paper. Contrary to the concluding
statement of the Comment, it is not difficult to find an ad hoc modification of
the form factor at low $Q$ that resolves the discrepancy and is consistent with
analyticity constraints. We emphasize once again that we do not consider such
an ad hoc modification of the proton form factor to be a solution of the puzzle
until a physical mechanism for it is found.


title:
Decoherence due to gravitational time dilation: analysis of competing
  decoherence effects

abstract:
  Recently, a static gravitational field, such as that of the Earth, was
proposed as a new source of decoherence [1]. We study the conditions under
which it becomes the dominant decoherence effect in typical interferometric
experiments. The following competing sources are considered: spontaneous
emission of light, absorption, scattering with the thermal photons and
collisions with the residual gas. We quantify all these effects. As we will
see, current experiments are off by several orders of magnitude. New ideas are
needed in order to achieve the necessary requirements: having as large as
system as possible, to increase gravitational decoherence, cool it and isolated
well enough to reduce thermal and collisional decoherence, and resolve very
small distances.


title: Topological Hochschild homology and the Hasse-Weil zeta function

abstract:
  We consider the Tate cohomology of the circle group acting on the topological
Hochschild homology of schemes. We show that in the case of a scheme smooth and
proper over a finite field, this cohomology theory naturally gives rise to the
cohomological interpretation of the Hasse-Weil zeta function by regularized
determinants envisioned by Deninger. In this case, the periodicity of the zeta
function is reflected by the periodicity of said cohomology theory, whereas
neither is periodic in general.


title: A short proof of a result of Katz and West

abstract:
  We give a short proof of a result due to Katz and West: Let $R$ be a
Noetherian ring and $I_1,\ldots,I_t$ ideals of $R$. Let $M$ and $N$ be finitely
generated $R$-modules and $N' \subseteq N$ a submodule. For every fixed $i \ge
0$, the sets $\mathrm{Ass}_R\left( \mathrm{Ext}_R^i(M, N/I_1^{n_1}\cdots
I_t^{n_t} N') \right)$ and $\mathrm{Ass}_R\left( \mathrm{Tor}_i^R(M,
N/I_1^{n_1}\cdots I_t^{n_t} N') \right)$ are independent of $(n_1,\ldots,n_t)$
for all sufficiently large $n_1,\ldots,n_t$.


title: On the Capacity of the Half-Duplex MIMO Gaussian Diamond Channel

abstract:
  In this paper, we analyze the 2-relay multiple-input multiple-output (MIMO)
Gaussian diamond channel. We show that a multihopping decode-and-forward with
multiple access (MDF-MAC) protocol achieves rates within a constant gap from
capacity when a channel parameter $\Delta$ is greater than zero. We also
identify the transmit covariance matrices to be used by each relay in the
multiple-access (MAC) state of the MDF-MAC protocol. As done for the
single-antenna 2-relay Gaussian diamond channel, the channel parameter $\Delta$
is defined to be the difference between the product of the capacities of the
links from the source to the two relays and the product of the capacities of
the links from the two relays to the destination.


title: Gysin maps, duality and Schubert classes

abstract:
  We establish a Gysin formula for Schubert bundles and a strong version of the
duality theorem in Schubert calculus on Grassmann bundles. We then combine them
to compute the fundamental classes of Schubert bundles in Grassmann bundles,
which yields a new proof of the Giambelli formula for vector bundles.


title:
Lower bounds for the variance of sequences in arithmetic progressions:
  primes and divisor functions

abstract:
  We develop a general method for lower bounding the variance of sequences in
arithmetic progressions mod $q$, summed over all $q \leq Q$, building on
previous work of Liu, Perelli, Hooley, and others. The proofs lower bound the
variance by the minor arc contribution in the circle method, which we lower
bound by comparing with suitable auxiliary exponential sums that are easier to
understand.
  As an application, we prove a lower bound of $(1-\epsilon) QN\log(Q^2/N)$ for
the variance of the von Mangoldt function $(\Lambda(n))_{n=1}^{N}$, on the
range $\sqrt{N} (\log N)^C \leq Q \leq N$. Previously such a result was only
available assuming the Riemann Hypothesis. We also prove a lower bound
$\gg_{k,\delta} Q N (\log N)^{k^2 - 1}$ for the variance of the divisor
functions $d_k(n)$, valid on the range $N^{1/2+\delta} \leq Q \leq N$, for any
natural number $k \geq 2$.


title:
On the inconsistency between cosmic stellar mass density and star
  formation rate up to $z\sim8$

abstract:
  In this paper, we test the discrepancy between the stellar mass density and
instantaneous star formation rate in redshift range $0<z<8$ using a large
observational data sample. We first compile the measurements of the stellar
mass densities up to $z\sim 8$. Comparing the observed stellar mass densities
with the time-integral of instantaneous star formation history, we find that
the observed stellar mass densities are lower than that implied from star
formation history at $z<4$. We also use Markov chain monte carlo method to
derive the best-fitting star formation history from the observed stellar mass
density data. At $0.5<z<6$, the observed star formation rate densities are
larger than the best-fitting one, especially at $z\sim2$ where by a factor of
about two. However, at lower ($z<0.5$) and higher redshifts ($z>6$), the
derived star formation history is consistent with the observations. This is the
first time to test the discrepancy between the observed stellar mass density
and instantaneous star formation rate up to very high redshift $z\approx8$
using the Markov chain monte carlo method and a varying recycling factor.
Several possible reasons for this discrepancy are discussed, such as
underestimation of stellar mass density, initial mass function and cosmic
metallicity evolution.


title: Linear equations on real algebraic surfaces

abstract:
  We prove that if a linear equation, whose coefficients are continuous
rational functions on a nonsingular real algebraic surface, has a continuous
solution, then it also has a continuous rational solution. This is known to
fail in higher dimensions.


title:
Coexistence of low moment magnetism and superconductivity in tetragonal
  FeS and suppression of $T_\mathrm{c}$ under pressure

abstract:
  We report local probe ($\mu$SR) measurements on the recently discovered
tetragonal FeS superconductor which has been predicted to be electronically
very similar to superconducting FeSe. Most remarkably, we find that low moment
($10^{-2}-10^{-3}\mu_\mathrm{B})$ disordered magnetism with a transition
temperature of $T_\mathrm{N}\approx 20$ K microscopically coexists with bulk
superconductivity below $T_\mathrm{c}=4.3(1)$ K. From transverse field $\mu$SR
we obtain an in-plane penetration depth $\lambda_\mathrm{ab}(0)=223(2)$ nm for
FeS. The temperature dependence of the corresponding superfluid density
$\lambda_\mathrm{ab}^{-2}(T)$ indicates a fully gapped superconducting state
and is consistent with a two gap s-wave model. Additionally, we find that the
superconducting $T_\mathrm{c}$ of FeS continuously decreases for hydrostatic
pressures up to 2.2 GPa.


title: Next-to-leading power threshold logarithms: a status report

abstract:
  There is ample evidence, dating as far back as Low's theorem, that the
universality of soft emissions extends beyond leading power in the soft energy.
This universality can, in principle, be exploited to generalise the formalism
of threshold resummations beyond leading power in the threshold variable. In
the past years, several phenomenological approaches have been partially
successful in performing such a resummation. Here, we briefly review some
recent developments which pave the way to a solution of this problem, at least
for electroweak annihilation processes.


title: Photon from the annihilation process with CGC in the $pA$ collision

abstract:
  We discuss the photon production in the $pA$ collision in a framework of the
color glass condensate (CGC) with expansion in terms of the proton color source
$\rho_p$. We work in a regime where the color density $\rho_A$ of the nucleus
is large enough to justify the CGC treatment, while soft gluons in the proton
could be dominant over quark components but do not yet belong to the CGC
regime, so that we can still expand the amplitude in powers of $\rho_p$. The
zeroth-order contribution to the photon production is known to appear from the
Bremsstrahlung process and the first-order corrections consist of the
Bremsstrahlung diagrams with pair produced quarks and the annihilation diagrams
of quarks involving a gluon sourced by $\rho_p$. Because the final states are
different there is no interference between these two processes. In this work we
elucidate calculation procedures in details focusing on the annihilation
diagrams only. Using the McLerran-Venugopalan model for the color average we
numerically calculate the photon production rate and discuss functional forms
that fit the numerical results.


title:
Light localization in hollow core fibers with a complicated shape of the
  core cladding boundary

abstract:
  In this paper we present a theoretical and numerical analysis of light
localization in hollow core microstructured fibers (HCMFs) with a complicated
shape of the core cladding boundary. The analysis is based on well established
models (for example, the ARROW model) and also on the models proposed for the
first time. In particular, we consider local and nonlocal mechanisms of light
localization in the waveguide structures with a determined type of discrete
rotational symmetry of the core cladding boundary. We interpret and analyze
mechanisms of light localization in negative curvature hollow core
microstructured fibers (NC HCMFs) and simplified HC PCFs with a polygonal shape
of the core cladding boundary.


title: The Series Product for Gaussian Quantum Input Processes

abstract:
  We present the theory for connecting quantum Markov components into a network
with quantum input processes in a Gaussian state (including thermal and
squeezed), not necessarily vacuum fields.One would expect on physical grounds
that the connection rules should be independent of the state of the input to
the network. To compute statistical properties, we use a version of Wicks'
Theorem involving fictitious vacuum fields (Fock space based representation of
the fields) and while this aids computation, and gives a rigorous formulation,
the various representations need not be unitarily equivalent. In particular, a
naive application of the connection rules would lead to the wrong answer. We
establish the correct interconnection rules, and show that while the quantum
stochastic differential equations of motion display explicitly the covariances
(thermal and squeezing parameters) of the Gaussian input fields We introduce
the Wick-Stratonovich form which leads to a way of writing these equations that
does not depend on these covariances and so corresponds to the universal
equations written in terms of formal quantum input processes. We show that a
wholly consistent theory of quantum open systems in series can be developed in
this way, and as required physically, is universal and in particular
representation-free.


title: Counting configuration-free sets in groups

abstract:
  We provide new examples of the asymptotic counting for the number of subsets
on groups of given size which are free of certain configurations. These
examples include sets without solutions to equations in non-abelian groups, and
linear configurations in abelian groups defined from group homomorphisms. The
results are obtained by combining the methodology of hypergraph containers
joint with arithmetic removal lemmas. As a consequence, random counterparts are
presented as well.


title:
Large nonsaturating magnetoresistance and signature of non-degenerate
  Dirac nodes in ZrSiS

abstract:
  While the discovery of Dirac and Weyl type excitations in electronic systems
is a major breakthrough in recent condensed matter physics, finding appropriate
materials for fundamental physics and technological applications, is an
experimental challenge. In all the reported materials, linear dispersion
survives only up to a few hundred meV from the Dirac or Weyl nodes. On the
other hand, real materials are subject to uncontrolled doping during
preparation and thermal effect near room temperature can hinder the rich
physics. In ZrSiS, ARPES measurements have shown an unusually robust linear
dispersion (up to $\sim$2 eV) with multiple non-degenerate Dirac nodes. In this
context, we present the magnetotransport study on ZrSiS crystal, which
represents a large family of materials (\textit{WHM} with \textit{W} = Zr, Hf;
\textit{H} = Si, Ge, Sn; \textit{M} = O, S, Se, Te) with identical band
topology. Along with extremely large and non-saturating magnetoresistance (MR),
$\sim$ 1.4 $\times$ 10$^{5}$ \% at 2 K and 9 T, it shows strong anisotropy
depending on the direction of the magnetic field. Quantum oscillation and Hall
effect measurements have revealed large hole and small electron Fermi pockets.
Non-trivial $\pi$ Berry phase confirms the Dirac fermionic nature for both
types of charge carriers. The long-sought relativistic phenomenon of massless
Dirac fermions, known as Adler-Bell-Jackiw chiral anomaly, has also been
observed.


title:
Yukawa couplings in 6D gauge-Higgs unification on $T^2/Z_N$ with
  magnetic fluxes

abstract:
  We discuss the Yukawa couplings in 6D gauge-Higgs unification models on
$T^2/Z_N$ in the presence of magnetic fluxes. We provide general formulae for
them, and numerically evaluate their magnitude in a specific model on
$T^2/Z_3$. Thanks to the nontrivial profiles of the zero-mode wave functions,
the top quark Yukawa coupling can be reproduced without introducing a large
representation of the gauge group for matter fields. However, it is difficult
to realize small Yukawa couplings only by the magnetic fluxes and the
Wilson-line phases because of the complicated structure of the mode functions
on $T^2/Z_N$ ($N=3,4,6$).


title:
Efficient distribution and improved security for reliable cloud storage
  system

abstract:
  The distributed data storage systems are constructed by large number of nodes
which are interconnected over a network. Each node in such peer-to-peer network
is vulnerable and at a potential risk for attack. The attackers can eavesdrop
the nodes and possibly modify their data. Hence distributed storage systems
should be secure apart from satisfying the reconstruction and repair
requirements. We constructed a distributed storage system, Twin MDS code
framework which is more efficient than the regenerating codes based storage
systems. We prove that this Twin MDS code framework gives better performance
than MBR codes and equal with MSR codes in the distribution process and
investigate its security performance comparing with the security of the MBR and
MSR codes. Such Twin MDS code framework is examined in an eavesdropper model
where passive attackers can access to the stored data or/and downloaded data
during the repair process. We demonstrate that the Twin MDS code framework
manages better results than MBR and MSR codes regarding the security in the
system.


title:
Counting spanning trees on fractal graphs and their asymptotic
  complexity

abstract:
  Using the method of spectral decimation and a modified version of Kirchhoff's
Matrix-Tree Theorem, a closed form solution to the number of spanning trees on
approximating graphs to a fully symmetric self-similar structure on a finitely
ramified fractal is given in Theorem \ref{thm:maintheoremfull}. We show how
spectral decimation implies the existence of the asymptotic complexity constant
and obtain some bounds for it. Examples calculated include the Sierpinski
Gasket, a non post critically finite analog of the Sierpinski Gasket, the
Diamond fractal, and the Hexagasket. For each example, the asymptotic
complexity constant is found.


title: The quest for an electric dipole moment of the neutron

abstract:
  Until this day no electric dipole moment of the neutron (nEDM) has been
observed. Why it is so vanishing small, escaping detection in the last 50
years, is not easy to explain. In general it is considered as the most
sensitive probe for the violation of the combined symmetry of charge and parity
(CP). A discovery could shed light on the poorly understood matter/anti-matter
asymmetry of the universe. As nucleon it might one day help to distinguish
different sources of CP-violation in combination with measurements of the
electron and diamagnetic EDMs. This proceedings articles presents an overview
of the most important concepts in searches for an nEDM and presents a brief
overview of the world wide efforts.


title:
Protecting entanglement from correlated amplitude damping channel using
  weak measurement and quantum measurement reversal

abstract:
  Based on the quantum technique of weak measurement, we propose a scheme to
protect the entanglement from correlated amplitude damping decoherence. In
contrast to the results of memoryless amplitude damping channel, we show that
the memory effects play a significant role in the suppression of entanglement
sudden death and protection of entanglement under severe decoherence. Moreover,
we find that the initial entanglement could be drastically amplified by the
combination of weak measurement and quantum measurement reversal even under the
correlated amplitude damping channel. The underlying mechanism can be
attributed to the probabilistic nature of weak measurements.


title:
Nonlinear Instability and Intermittent Nature of Magnetic Reconnection
  in Solar Chromosphere

abstract:
  The recent observations of Singh et al. (2012) have shown multiple plasma
ejections and the intermittent nature of magnetic reconnection in the solar
chromosphere, highlighting the need for fast reconnection to occur in highly
collisional plasma. However, the physical process through which fast magnetic
reconnection occurs in partially ionized plasma, like the solar chromosphere,
is still poorly understood. It has been shown that for sufficiently high
magnetic Reynolds numbers, Sweet-Parker current sheets can become unstable
leading to tearing mode instability and plasmoid formation, but when dealing
with a partially ionized plasma the strength of coupling between the ions and
neutrals plays a fundamental role in determining the dynamics of the system. We
propose that as the reconnecting current sheet thins and the tearing
instability develops, plasmoid formation passes through strongly,
intermediately, and weakly coupled (or decoupled) regimes, with the time scale
for the tearing mode instability depending on the frictional coupling between
ions and neutrals. We present calculations for the relevant time scales for
fractal tearing in all three regimes. We show that as a result of the tearing
mode instability and the subsequent non-linear instability due to the
plasmoid-dominated reconnection, the Sweet-Parker current sheet tends to have a
fractal-like structure, and when the chromospheric magnetic field is
sufficiently strong the tearing instability can reach down to kinetic scales,
which are hypothesized to be necessary for fast reconnection.


title: The Cool Giant HD 77361 - A Super Li-Rich Star

abstract:
  Super Li-rich stars form a very small and enigmatic group whose existence
cannot be explained in terms of the standard stellar evolution theory. The goal
of our study is to check the reality of this group of cool giants based on an
independent technique. We have carried out such a check using the K giant HD
77361 (HR 3597), which has previously been assigned to this rare type, as an
example. We have redetermined the effective temperature Teff and surface
gravity log g for this star. We have applied two different methods, photometric
and spectroscopic, to estimate Teff (the accuracy of the Li-abundance
determination depends significantly on this parameter). The value of log g has
been found from the highly accurate parallax of this nearby star. To apply the
photometric method of determining Teff, we have performed UBV observations of
the star, which yielded V = 6.18 +/- 0.03, B - V = 1.13 +/- 0.01, and U - B =
1.18+/-0.05. The following parameters of the star have been found: effective
temperature Teff = 4370+/- 100 K, surface gravity log g = 2.30 +/- 0.10, iron
abundance log e(Fe) = 7.49 +/- 0.14, microturbulence Vt = 1.1 +/- 0.2 km/s,
rotational velocity V sin i = 4.5 km/s, and mass M = 1.3 +/- 0.2 Msun. The
lithium abundance has been determined from a non-LTE analysis of three Li I
lines: the resonance line at 6707.8 ?A and the subordinate lines at 6103.6 and
8126.4 ?A (the latter in a blend with a CN molecular line). We have found a
high lithium abundance, log e(Li) = 3.75 +/- 0.11, which exceeds considerably
the initial abundance log e(Li) = 3.2 +/- 0.1 for young stars in the solar
neighborhood. Thus, we have confirmed that the K giant HD 77361 actually
belongs to the type of super Li-rich stars.


title: Conformal Killing 2-forms on 4-dimensional manifolds

abstract:
  We study 4-dimensional simply connected Lie groups $G$ with left-invariant
Riemannian metric $g$ admitting non-trivial conformal Killing 2-forms. We show
that either the real line defined by such a form is invariant under the group
action, or the metric is half conformally flat. In the first case, the problem
reduces to the study of invariant conformally K\"ahler structures, whereas in
the second case, the Lie algebra of $G$ belongs (up to homothety) to a finite
list of families of metric Lie algebras.


title: The Structure of $W_4$-Immersion-Free Graphs

abstract:
  We study the structure of graphs that do not contain the wheel on 5 vertices
W4 as an immersion, and show that these graphs can be constructed via 1, 2, and
3-edge-sums from subcubic graphs and graphs of bounded treewidth.


title: Quasi-integrable deformations of the $SU(3)$ Affine Toda Theory

abstract:
  We consider deformations of the $SU(3)$ Affine Toda theory (AT) and
investigate the integrability properties of the deformed theories. We find that
for some special deformations all conserved quantities change to being
conserved only asymptotically, {\it i.e.} in the process of the scattering of
two solitons these charges do vary in time, but they return, after the
scattering, to the values they had prior to the scattering. This phenomenon,
which we have called quasi-integrability, is related to special properties of
the two-soliton solutions under space-time parity transformations. Some
properties of the AT solitons are discussed, especially those involving
interesting static multi-soliton solutions. We support our analytical studies
with detailed numerical ones in which the time evolution has been simulated by
the 4th order Runge-Kutta method. We find that for some perturbations the
solitons repel and for the others they form a quasi-bound state. When we send
solitons towards each other they can repel when they come close together with
or without `flipping' the fields of the model. The solitons radiate very little
and appear to be stable. These results support the ideas of
quasi-integrability, {\it i.e.} that many effects of integrability also
approximately hold for the deformed models.


title: Code Generation for Event-B

abstract:
  Stepwise refinement and Design-by-Contract are two formal approaches for
modelling systems. These approaches are widely used in the development of
systems. Both approaches have (dis-)advantages. This thesis aims to answer, is
it possible to combine both approaches in the development of systems, providing
the user with the benefits of both? We answer this question by translating the
stepwise refinement method with Event-B to Design-by-Contract with Java and
JML, so users can take full advantage of both formal approaches without losing
their benefits. This thesis presents a set of syntactic rules that translates
Event-B to JML-annotated Java code. It also presents the implementation of the
syntactic rules as the EventB2Java tool. We used the tool to translate several
Event-B models. It generated JML-annotated Java code for all the considered
models that serve as initial implementation. We also used EventB2Java for the
development of two software applications. Additionally, we compared EventB2Java
against two other tools for Event-B code generation. EventB2Java enables users
to start the software development process in Event-B, where users can model the
system and prove its consistency, to then transition to JML-annotated Java
code, where users can continue the development process.


title: Slave fermion formalism for the tetrahedral spin chain

abstract:
  We use the SU(2) slave fermion approach to study a tetrahedral spin 1/2
chain, which is a one-dimensional generalization of the two dimensional Kitaev
honeycomb model. Using the mean field theory, coupled with a gauge fixing
procedure to implement the single occupancy constraint, we obtain the phase
diagram of the model. We then show that it matches the exact results obtained
earlier using the Majorana fermion representation. We also compute the
spin-spin correlation in the gapless phase and show that it is a spin liquid.
Finally, we map the one-dimensional model in terms of the slave fermions to the
model of 1D p-wave superconducting model with complex parameters and show that
the parameters of our model fall in the topological trivial regime and hence
does not have edge Majorana modes.


title:
Generic non-uniqueness of complete $H$-surfaces embedded in
  $\mathbb{H}^3$

abstract:
  We prove that, given $|H|<1$, a generic simple closed curve embedded in the
asymptotic boundary of $\mathbb{H}^3$ (with respect to the supremum metric)
bounds more than one complete surface embedded in $\mathbb{H}^3$ which has
constant mean curvature $H$. We remark that this is not true for the space of
simple closed $\text{C}^1$-curves.


title: Non-binary branching process and Non-Markovian exploration process

abstract:
  We study the exploration (or height) process of a continuous time non-binary
Galton-Watson random tree, in the subcritical, critical and supercritical
cases. Thus we consider the branching process in continuous time (Z_{t})_{t\geq
0}, which describes the number of offspring alive at time t. We then
renormalize our branching process and exploration process, and take the weak
limit as the size of the population tends to infinity. Finally we deduce a
Ray-Knight representation.


title: Imaginary projections of polynomials

abstract:
  We introduce the imaginary projection of a multivariate polynomial $f \in
\mathbb{C}[\mathbf{z}]$ as the projection of the variety of $f$ onto its
imaginary part, $\mathcal{I}(f) \ = \ \{\text{Im}(\mathbf{z}) \, : \,
\mathbf{z} \in \mathcal{V}(f) \}$. Since a polynomial $f$ is stable if and only
if $\mathcal{I}(f) \cap \mathbb{R}_{>0}^n \ = \ \emptyset$, the notion offers a
novel geometric view underlying stability questions of polynomials.
  We show that the connected components of the complement of the closure of the
imaginary projections are convex, thus opening a central connection to the
theory of amoebas and coamoebas. Building upon this, the paper establishes
structural properties of the components of the complement, such as lower bounds
on their maximal number, proves a complete classification of the imaginary
projections of quadratic polynomials and characterizes the limit directions for
polynomials of arbitrary degree.


title:
Computing with hardware neurons: spiking or classical? Perspectives of
  applied Spiking Neural Networks from the hardware side

abstract:
  While classical neural networks take a position of a leading method in the
machine learning community, spiking neuromorphic systems bring attention and
large projects in neuroscience. Spiking neural networks were shown to be able
to substitute networks of classical neurons in applied tasks. This work
explores recent hardware designs focusing on perspective applications (like
convolutional neural networks) for both neuron types from the energy efficiency
side to analyse whether there is a possibility for spiking neuromorphic
hardware to grow up for a wider use. Our comparison shows that spiking hardware
is at least on the same level of energy efficiency or even higher than
non-spiking on a level of basic operations. However, on a system level, spiking
systems are outmatched and consume much more energy due to inefficient data
representation with a long series of spikes. If spike-driven applications,
minimizing an amount of spikes, are developed, spiking neural systems may reach
the energy efficiency level of classical neural systems. However, in the near
future, both type of neuromorphic systems may benefit from emerging memory
technologies, minimizing the energy consumption of computation and memory for
both neuron types. That would make infrastructure and data transfer energy
dominant on the system level. We expect that spiking neurons have some
benefits, which would allow achieving better energy results. Still the problem
of an amount of spikes will still be the major bottleneck for spiking hardware
systems.


title: Stark effect spectroscopy of mono- and few-layer MoS$_{2}$

abstract:
  We demonstrate electrical control of the A-exciton interband transition in
mono- and few-layer $MoS_{2}$ crystals embedded into photocapacitor devices via
the DC Stark effect. Electric field dependent low-temperature photoluminescence
spectroscopy reveals a significant tuneability of the A-exciton transition
energy, up to $\sim 16 meV$, from which we extract the mean DC exciton
polarisability $<\bar{\beta}>_{N} = (0.58 \pm 0.25) \cdot 10^{-8} DmV^{-1}$.
The exciton polarisability is shown to be layer-independent, indicating a
strong localisation of both electron and hole wave functions in each individual
layer.


title: Issues with the Smith-Wilson method

abstract:
  The objective of the present paper is to analyse various features of the
Smith-Wilson method used for discounting under the EU regulation Solvency II,
with special attention to hedging. In particular, we show that all key rate
duration hedges of liabilities beyond the Last Liquid Point will be peculiar.
Moreover, we show that there is a connection between the occurrence of negative
discount factors and singularities in the convergence criterion used to
calibrate the model. The main tool used for analysing hedges is a novel
stochastic representation of the Smith-Wilson method. Further, we provide
necessary conditions needed in order to construct similar, but hedgeable,
discount curves.