title: Interactive Tools and Tasks for the Hebrew Bible

abstract:
  This contribution to a special issue on "Computer-aided processing of
intertextuality" in ancient texts will illustrate how using digital tools to
interact with the Hebrew Bible offers new promising perspectives for
visualizing the texts and for performing tasks in education and research. This
contribution explores how the corpus of the Hebrew Bible created and maintained
by the Eep Talstra Centre for Bible and Computer can support new methods for
modern knowledge workers within the field of digital humanities and theology be
applied to ancient texts, and how this can be envisioned as a new field of
digital intertextuality. The article first describes how the corpus was used to
develop the Bible Online Learner as a persuasive technology to enhance language
learning with, in, and around a database that acts as the engine driving
interactive tasks for learners. Intertextuality in this case is a matter of
active exploration and ongoing practice. Furthermore, interactive
corpus-technology has an important bearing on the task of textual criticism as
a specialized area of research that depends increasingly on the availability of
digital resources. Commercial solutions developed by software companies like
Logos and Accordance offer a market-based intertextuality defined by the
production of advanced digital resources for scholars and students as useful
alternatives to often inaccessible and expensive printed versions. It is
reasonable to expect that in the future interactive corpus technology will
allow scholars to do innovative academic tasks in textual criticism and
interpretation. We have already seen the emergence of promising tools for text
categorization, analysis of translation shifts, and interpretation. Broadly
speaking, interactive tools and tasks within the three areas of language
learning, textual criticism, and Biblical studies illustrate a new kind of
intertextuality emerging within digital humanities.


title: OD elements of countable OD sets in the Solovay model

abstract:
  It is true in the Solovay model that every countable ordinal-definable set of
sets of reals contains only ordinal-definable elements.


title: Probing the Nuclear Spin-Lattice Relaxation Time at the Nanoscale

abstract:
  Nuclear spin-lattice relaxation times are measured on copper using magnetic
resonance force microscopy performed at temperatures down to 42 mK. The low
temperature is verified by comparison with the Korringa relation. Measuring
spin-lattice relaxation times locally at very low temperatures opens up the
possibility to measure the magnetic properties of inhomogeneous electron
systems realized in oxide interfaces, topological insulators and other strongly
correlated electron systems such as high-Tc superconductors.


title:
Circulating current in 1D Hubbard rings with long-range hopping:
  Comparison between exact diagonalization method and mean-field approach

abstract:
  The interplay between Hubbard interaction, long-range hopping and disorder on
persistent current in a mesoscopic one-dimensional conducting ring threaded by
a magnetic flux $\phi$ is analyzed in detail. Two different methods, exact
numerical diagonalization and Hartree-Fock mean field theory, are used to
obtain numerical results from the many-body Hamiltonian. The current in a
disordered ring gets enhanced as a result of electronic correlation and it
becomes more significant when contributions from higher order hoppings, even if
they are too small compared to nearest-neighbor hopping, are taken into
account. Certainly this can be an interesting observation in the era of
long-standing controversy between theoretical and experimental results of
persistent current amplitudes. Along with these we also find half-flux quantum
periodic current for some typical electron fillings and kink-like structures at
different magnetic fluxes apart from $\phi=0$ and $\pm \phi_0/2$. The scaling
behavior of current is also discussed for the sake of completeness of our
present analysis.


title: Spin Hall Effect Induced Spin Transfer Through an Insulator

abstract:
  When charge current passes through a normal metal that exhibits spin Hall
effect, spin accumulates at the edge of the sample in the transverse direction.
We predict that this spin accumulation, or spin voltage, enables quantum
tunneling of spin through an insulator or vacuum to reach a ferromagnet without
transferring charge. In a normal metal/insulator/ferromagnetic insulator
trilayer (such as Pt/oxide/YIG), the quantum tunneling explains the
spin-transfer torque and spin pumping that exponentially decay with the
thickness of the insulator. In a normal metal/insulator/ferromagnetic metal
trilayer (such as Pt/oxide/Co), the spin transfer in general does not decay
monotonically with the thickness of the insulator. Combining with the spin Hall
magnetoresistance, this tunneling mechanism points to the possibility of a new
type of tunneling spectroscopy that can probe the magnon density of states of a
ferromagnetic insulator in an all-electrical and noninvasive manner.


title:
Electronic Structure of the Dark Surface of the Weak Topological
  Insulator Bi14Rh3I9

abstract:
  The compound Bi14Rh3I9 consists of ionic stacks of intermetallic
[(Bi4Rh)3I]2+ and insulating [Bi2I8]2- layers and has been identified to be a
weak topological insulator. Scanning tunneling microscopy revealed the robust
edge states at all step edges of the cationic layer as a topological
fingerprint. However, these edge states are found 0.25 eV below the Fermi level
which is an obstacle for transport experiments. Here, we address this obstacle
by comparing results of density functional slab calculations with scanning
tunneling spectroscopy and angle-resolved photoemission spectroscopy. We show
that the n-type doping of the intermetallic layer is intrinsically caused by
the polar surface and is well screened towards the bulk. In contrast, the
anionic "spacer" layer shows a gap at the Fermi level, both, on the surface and
in the bulk, i.e. it is not surface-doped due to iodine desorption. The well
screened surface dipole implies that a buried edge state, probably already
below a single spacer layer, is located at the Fermi level. Consequently, a
multilayer step covered by a spacer layer could provide access to the transport
properties of the topological edge states. In addition, we find a lateral
electronic modulation of the topologically non-trivial surface layer which is
traced back to the coupling with the underlying zigzag chain structure of the
spacer layer.


title:
Rare Higgs three body decay induced by top-Higgs FCNC coupling in the
  littlest Higgs Model with T-parity

abstract:
  Motivated by the search for flavor-changing neutral current (FCNC) top quark
decays at the LHC, we calculate rare Higgs three body decay $H\rightarrow Wbc$
induced by top-Higgs FCNC coupling in the littlest Higgs model with
T-parity(LHT). We find that the branching ratios of $H\rightarrow Wbc$ in the
LHT model can reach $\mathcal O(10^{-7})$ in the allowed parameter space.


title:
Electron scattering on hydrogen and deuterium molecules at 14-25 keV by
  the "Troitsk nu-mass" experiment

abstract:
  We've performed precise measurements of electron scattering on molecular
hydrogen and deuterium by using the "Troitsk nu-mass" setup. Electrons were
generated by the electron gun with an energy line width better than 0.3 eV. The
electron energies were 14, 17, 18.7, 19 and 25 keV. The windowless gaseous
tritium source (WGTS) was filled by hydrogen isotopes and served as a target.
The total column density was adjusted to form a length of 0.35--0.7 of the
electron mean free path. The integral spectrum of scattered electrons was
measured by the electrostatic spectrometer with a magnetic adiabatic
collimation and relative energy resolution 8.3 10^{-5}. As a result, the shapes
of molecular excitation and ionization spectra were extracted for both
isotopes. We did not find any difference between hydrogen and deuterium
targets. The relative energy dependence was extracted too.


title:
Reactivity of OH and CH3OH between 22 and 64 K: Modelling the gas phase
  production of CH3O in Barnard 1b

abstract:
  In the last years, ultra-low temperature chemical kinetic experiments have
demonstrated that some gas-phase reactions are much faster than previously
thought. One example is the reaction between OH and CH3OH, which has been
recently found to be accelerated at low temperatures yielding CH3O as main
product. This finding opened the question of whether the CH3O observed in the
dense core Barnard 1b could be formed by the gas-phase reaction of CH3OH and
OH. Several chemical models including this reaction and grain-surface processes
have been developed to explain the observed abundance of CH$_3$O with little
success. Here we report for the first time rate coefficients for the gas-phase
reaction of OH and CH3OH down to a temperature of 22 K, very close to those in
cold interstellar clouds. Two independent experimental set-ups based on the
supersonic gas expansion technique coupled to the pulsed laser photolysis-laser
induced fluorescence technique were used to determine rate coefficients in the
temperature range 22-64 K. The temperature dependence obtained in this work can
be expressed as k(22-64 K) = (3.6+/-0.1)e-12 (T/ 300)^(-1.0+/-0.2) cm3
molecule-1 s-1. Implementing this expression in a chemical model of a cold
dense cloud results in CH3O/CH3OH abundance ratios similar or slightly lower
than the value of 3e-3 observed in Barnard 1b. This finding confirms that the
gas-phase reaction between OH and CH3OH is an important contributor to the
formation of interstellar CH3O. The role of grain-surface processes in the
formation of CH3O, although it cannot be fully neglected, remains
controversial.


title: A Variational Perspective on Accelerated Methods in Optimization

abstract:
  Accelerated gradient methods play a central role in optimization, achieving
optimal rates in many settings. While many generalizations and extensions of
Nesterov's original acceleration method have been proposed, it is not yet clear
what is the natural scope of the acceleration concept. In this paper, we study
accelerated methods from a continuous-time perspective. We show that there is a
Lagrangian functional that we call the \emph{Bregman Lagrangian} which
generates a large class of accelerated methods in continuous time, including
(but not limited to) accelerated gradient descent, its non-Euclidean extension,
and accelerated higher-order gradient methods. We show that the continuous-time
limit of all of these methods correspond to traveling the same curve in
spacetime at different speeds. From this perspective, Nesterov's technique and
many of its generalizations can be viewed as a systematic way to go from the
continuous-time curves generated by the Bregman Lagrangian to a family of
discrete-time accelerated algorithms.


title: The sphere packing problem in dimension 8

abstract:
  In this paper we prove that no packing of unit balls in Euclidean space
$\mathbb{R}^8$ has density greater than that of the $E_8$-lattice packing.


title: Noncommutative harmonic analysis on semigroup and ultracontractivity

abstract:
  We extend some classical results of Cowling and Meda to the noncommutative
setting. Let $(T_t)_{t>0}$ be a symmetric contraction semigroup on a
noncommutative space $L_p(\mathcal{M}),$ and let the functions $\phi$ and
$\psi$ be regularly related. We prove that the semigroup $(T_t)_{t>0}$ is
$\phi$-ultracontractive, i.e. $\|T_t x\|_\infty \leq C \phi(t)^{-1} \|x\|_1$
for all $x\in L_1(\mathcal{M})$ and $ t>0$ if and only if its infinitesimal
generator $L$ has the Sobolev embedding properties: $\|\psi(L)^{-\alpha} x\|_q
\leq C'\|x\|_p$ for all $x\in L_p(\mathcal{M}),$ where $1<p<q<\infty$ and
$\alpha =\frac{1}{p}-\frac{1}{q}.$ We establish some noncommutative spectral
multiplier theorems and maximal function estimates for generator of
$\phi$-ultracontractive semigroup. We also show the equivalence between
$\phi$-ultracontractivity and logarithmic Sobolev inequality for some special
$\phi$. Finally, we gives some results on local ultracontractivity.


title: Resonant Diphoton Phenomenology Simplified

abstract:
  A framework is proposed to describe resonant diphoton phenomenology at hadron
colliders in full generality. It can be employed for a comprehensive
model-independent interpretation of the experimental data. Within the general
framework, few benchmark scenarios are defined as representative of the various
phenomenological options and/or of motivated new physics scenarios. Their usage
is illustrated by performing a characterization of the 750 GeV excess, based on
a recast of available experimental results.
  We also perform an assessment of which properties of the resonance could be
inferred, after discovery, by a careful experimental study of the diphoton
distributions. These include the spin J of the new particle and its dominant
production mode. Partial information on its CP-parity can also be obtained, but
only for $J\geq2$. The complete determination of the resonance CP properties
requires studying the pattern of the initial state radiation that accompanies
the resonant diphoton production.


title: Rotating Drops of Axion Dark Matter

abstract:
  We consider how QCD axions produced by the misalignment mechanism could form
galactic dark matter halos. We recall that stationary, gravitationally stable
axion field configurations have the size of an asteroid with masses of order
$10^{-13} $ solar masses (because gradient pressure is insufficient to support
a larger object). We call such field configurations "drops". We explore whether
rotating drops could be larger, and find that their mass could increase by a
factor ~ 10. Remarkably this mass is comparable to the mass of miniclusters
generated from misalignment axions in the scenario where the axion is born
after inflation. We speculate that misalignment axions today are in the form of
drops, contributing to dark matter like a distribution of asteroids (and not as
a coherent oscillating background field). We consider some observational
signatures of the drops, which seem consistent with a galactic halo made of
axion dark matter.


title: Restriction estimates using polynomial partitioning II

abstract:
  We improve the estimates in the restriction problem in dimension $n \ge 4$.
To do so, we establish a weak version of a $k$-linear restriction estimate for
any $k$. The exponents in this weak $k$-linear estimate are sharp for all $k$
and $n$.


title: The need for the Higgs boson in the Standard Model

abstract:
  We review the role of the Higgs boson in preserving unitarity of the
scattering amplitudes in the Standard Model (SM). We will look at the processes
$\nu_e + \bar{\nu}_e \rightarrow W^-_L +W^+_L $, $ W^-_L + W^+_L \rightarrow
W^-_L +W^+_L $ and $e^- + e^+ \rightarrow W^-_L +W^+_L $ for longitudinally
polarized gauge bosons. Special emphasis will be put in using algebraic methods
to evaluate the amplitudes and cross sections. This note is based on Lectures
given at the IDPASC Schools in Udine (2012) and Braga (2014).


title: Quantum Quenches in the Luttinger model and its close relatives

abstract:
  A number of results on quantum quenches in the Luttinger and related models
are surveyed with emphasis on post-quench correlations. For the Luttinger model
and initial gaussian states, we discuss both sudden and smooth quenches of the
interaction and the emergence of a steady state described by a generalized
Gibbs ensemble. Comparisons between analytics and numerics, and the question of
universality or lack thereof are also discussed. The relevance of the
theoretical results to current and future experiments in the fields of
ultracold atomic gases and mesoscopic systems of electrons is also briefly
touched upon. Wherever possible, our approach is pedagogical and
self-contained. This work is dedicated to the memory of our colleague Alejandro
Muramatsu.


title: Noncommutative augmentation categories

abstract:
  To a differential graded algebra with coefficients in a noncommutative
algebra, by dualisation we associate an $A_\infty$-category whose objects are
augmentations. This generalises the augmentation category of Bourgeois and
Chantraine to the noncommutative world.


title: Dual gauge field theory of quantum liquid crystals in two dimensions

abstract:
  We present a self-contained review of the theory of dislocation-mediated
quantum melting at zero temperature in two spatial dimensions. The theory
describes the liquid-crystalline phases with spatial symmetries in between a
quantum crystalline solid and an isotropic superfluid: quantum nematics and
smectics. It is based on an Abelian-Higgs-type duality mapping of phonons onto
gauge bosons ("stress photons"), which encode for the capacity of the crystal
to propagate stresses. Dislocations and disclinations, the topological defects
of the crystal, are sources for the gauge fields and the melting of the crystal
can be understood as the proliferation (condensation) of these defects, giving
rise to the Anderson-Higgs mechanism on the dual side. For the liquid crystal
phases, the shear sector of the gauge bosons becomes massive signaling that
shear rigidity is lost. Resting on symmetry principles, we derive the
phenomenological imaginary time actions of quantum nematics and smectics and
analyze the full spectrum of collective modes. The quantum nematic is a
superfluid having a true rotational Goldstone mode due to rotational symmetry
breaking, and the origin of this 'deconfined' mode is traced back to the
crystalline phase. The two-dimensional quantum smectic turns out to be a
dizzyingly anisotropic phase with the collective modes interpolating between
the solid and nematic in a non-trivial way. We also consider electrically
charged bosonic crystals and liquid crystals, and carefully analyze the
electromagnetic response of the quantum liquid crystal phases. In particular,
the quantum nematic is a real superconductor and shows the Meissner effect.
Their special properties inherited from spatial symmetry breaking show up
mostly at finite momentum, and should be accessible by momentum-sensitive
spectroscopy.


title: Mass spectra in softly broken ${\cal N}=2$ SQCD

abstract:
  Considered are ${\cal N}=2\, SU(N_c)$ or $U(N_c)$ SQCD with $N_F<2N_c-1$
quark flavors with the quark mass term $m{\rm Tr}\,({\bar Q} Q)$ in the
superpotential. ${\cal N}=2$ supersymmetry is softly broken down to ${\cal
N}=1$ by the mass term $\mu_{\rm x}{\rm Tr}\,(X^2)$ of colored adjoint scalar
partners of gluons, $\mu_{\rm x}\ll\Lambda_2$ ($\Lambda_2$ is the scale factor
of the $SU(N_c)$ gauge coupling).
  There is a large number of different types of vacua in these theories with
both unbroken and spontaneously broken flavor symmetry, $U(N_F)\rightarrow
U({\rm n}_1)\times U({\rm n}_2)$. We consider in this paper the large subset of
these vacua with the unbroken nontrivial $Z_{2N_c-N_F\geq 2}$ discrete
symmetry, at different hierarchies between the Lagrangian parameters
$m\gtrless\Lambda_2,\,\, \mu_{\rm x}\gtrless m$. The forms of low energy
Lagrangians, quantum numbers of light particles and mass spectra are described
in the main text for all these vacua.
  The calculations of power corrections to the leading terms of the low energy
quark and dyon condensates are presented in two important Appendices. These
calculations confirm additionally in a non-trivial way a self-consistency of
the whole approach.
  Our results differ essentially from corresponding results in recent related
papers arXiv:1304.0822, arXiv:1403.6086, and arXiv:1704.06201 of M.Shifman and
A.Yung (and in a number of their numerous previous papers on this subject), and
we explain in the text the reasons for these differences (see also the extended
critique of a number of results of these authors in section 8 of
arXiv:1308.5863).


title:
Non-equilibrium ionization by a periodic electron beam. I. Synthetic
  coronal spectra and implications for interpretation of observations

abstract:
  Context. Coronal heating is currently thought to proceed via the mechanism of
nanoflares, small-scale and possibly recurring heating events that release
magnetic energy. Aims. We investigate the effects of a periodic high-energy
electron beam on the synthetic spectra of coronal Fe ions. Methods. Initially,
the coronal plasma is assumed to be Maxwellian with a temperature of 1 MK. The
high-energy beam, described by a kappa-distribution, is then switched on every
period $P$ for the duration of P/2. The periods are on the order of several
tens of seconds, similar to exposure times or cadences of space-borne
spectrometers. Ionization, recombination, and excitation rates for the
respective distributions are used to calculate the resulting non-equilibrium
ionization state of Fe and the instantaneous and period-averaged synthetic
spectra. Results. Under the presence of the periodic electron beam, the plasma
is out of ionization equilibrium at all times. The resulting spectra averaged
over one period are almost always multithermal if interpreted in terms of
ionization equilibrium for either a Maxwellian or a kappa-distribution.
Exceptions occur, however; the EM-loci curves appear to have a nearly
isothermal crossing-point for some values of kappa_s. The instantaneous spectra
show fast changes in intensities of some lines, especially those formed outside
of the peak of the respective EM(T) distributions if the ionization equilibrium
is assumed.


title: Mixed and stabilized finite element methods for the obstacle problem

abstract:
  We discretize the Lagrange multiplier formulation of the obstacle problem by
mixed and stabilized finite element methods. A priori and a posteriori error
estimates are derived and numerically verified.


title: Betweenness Centrality of Cartesian Product of Graphs

abstract:
  Betweenness centrality is a widely-used measure in the analysis of large
complex networks. It measures the potential or power of a vertex to control the
communication over the network under the assumption that information primarily
flows over the shortest paths between them. In this paper we prove several
results on betweenness centrality of Cartesian product of graphs.


title: Item2Vec: Neural Item Embedding for Collaborative Filtering

abstract:
  Many Collaborative Filtering (CF) algorithms are item-based in the sense that
they analyze item-item relations in order to produce item similarities.
Recently, several works in the field of Natural Language Processing (NLP)
suggested to learn a latent representation of words using neural embedding
algorithms. Among them, the Skip-gram with Negative Sampling (SGNS), also known
as word2vec, was shown to provide state-of-the-art results on various
linguistics tasks. In this paper, we show that item-based CF can be cast in the
same framework of neural word embedding. Inspired by SGNS, we describe a method
we name item2vec for item-based CF that produces embedding for items in a
latent space. The method is capable of inferring item-item relations even when
user information is not available. We present experimental results that
demonstrate the effectiveness of the item2vec method and show it is competitive
with SVD.


title:
A p-adaptive local discontinuous galerkin level set method for Willmore
  flow

abstract:
  The level set method is often used to capture interface behavior in two or
three dimensions. In this paper, we present a combination of local
discontinuous Galerkin (LDG) method and level set method for simulating
Willmore flow. The LDG scheme is energy stable and mass conservative, which are
good properties comparing with other numerical methods. In addition, to enhance
the efficiency of the proposed LDG scheme and level set method, we employ a
p-adaptive local discontinuous Galerkin technique, which applies high order
polynomial approximations around the zero level set and low order ones away
from the zero level set. A major advantage of the level set method is that the
topological changes are well defined and easily performed. In particular, given
the stiffness of Willmore flow, a high order semi-implicit Runge-Kutta method
is employed for time discretization, which allows larger time step. The
equations at the implicit time level are linear, we demonstrate an efficient
and practical multi-grid solver to solve the equations. Numerical examples are
given to illustrate the combination of the LDG scheme and level set method
provides an efficient and practical approach when simulating the Willmore flow.


title: Impact of subsampling and pruning on random forests

abstract:
  Random forests are ensemble learning methods introduced by Breiman (2001)
that operate by averaging several decision trees built on a randomly selected
subspace of the data set. Despite their widespread use in practice, the
respective roles of the different mechanisms at work in Breiman's forests are
not yet fully understood, neither is the tuning of the corresponding
parameters. In this paper, we study the influence of two parameters , namely
the subsampling rate and the tree depth, on Breiman's forests performance. More
precisely, we show that fully developed sub-sampled forests and pruned (without
subsampling) forests have similar performances, as long as respective
parameters are well chosen. Moreover , experiments show that a proper tuning of
subsampling or pruning lead in most cases to an improvement of Breiman's
original forests errors.


title:
Josephson effect in multi-terminal superconductor-ferromagnet junctions
  coupled via triplet components

abstract:
  On the basis of the Usadel equation we study a multi-terminal Josephson
junction. This junction is composed by "magnetic" superconductors
S$_{\text{m}}$ which have singlet pairing and are separated from the normal
n~wire by spin filters so that the Josephson coupling is caused only by fully
polarized triplet components. We show that there is no interaction between
triplet Cooper pairs with antiparallel total spin orientations. The presence of
an additional singlet superconductor S attached to the n wire leads to a finite
Josephson current $I_{\text{Q}}$ with an unusual current--phase relation. The
density of states in the n wire for different orientations of spins of Cooper
pairs is calculated. We derive a general formula for the current $I_{\text{Q}}$
in a multi-terminal Josephson contact and apply this formula for analysis of
two four-terminal Josephson junctions of different structures. It is shown in
particular that both the "nematic" and the "magnetic" cases can be realized in
these junctions. In a two-terminal structure with parallel filter orientations
and in a three-terminal structure with antiparallel filter orientations of the
"magnetic" superconductors with attached additional singlet superconductor, we
find a nonmonotonic temperature dependence of the critical current. Also, in
these structures, the critical current shows a Riedel peak like dependence on
the exchange field in the "magnetic" superconductors. Although there is no
current through the S/n interface due to orthogonality of the singlet and
triplet components, the phase of the order parameter in the superconuctor S is
shown to affect the Josephson current in a multi-terminal structure.


title:
Strong Correlation Effects on Topological Quantum Phase Transitions in
  Three Dimensions

abstract:
  We investigate the role of short-ranged electron-electron interactions in a
paradigmatic model of three dimensional topological insulators, using dynamical
mean-field theory and focusing on non magnetically ordered solutions. The
non-interacting band-structure is controlled by a mass term M, whose value
discriminates between three different insulating phases, a trivial band
insulator and two distinct topologically non-trivial phases. We characterize
the evolution of the transitions between the different phases as a function of
the local Coulomb repulsion U and find a remarkable dependence of the U -M
phase diagram on the value of the local Hund's exchange coupling J. However,
regardless the value of J, following the evolution of the topological
transition line between a trivial band insulator and a topological insulator,
we find a critical value of U separating a continuous transition from a
first-order one. When the Hund's coupling is significant, a Mott insulator is
stabilized at large U . In proximity of the Mott transition we observe the
emergence of an anomalous "Mott-like" strong topological insulating state.


title: Novel Speech Features for Improved Detection of Spoofing Attacks

abstract:
  Now-a-days, speech-based biometric systems such as automatic speaker
verification (ASV) are highly prone to spoofing attacks by an imposture. With
recent development in various voice conversion (VC) and speech synthesis (SS)
algorithms, these spoofing attacks can pose a serious potential threat to the
current state-of-the-art ASV systems. To impede such attacks and enhance the
security of the ASV systems, the development of efficient anti-spoofing
algorithms is essential that can differentiate synthetic or converted speech
from natural or human speech. In this paper, we propose a set of novel speech
features for detecting spoofing attacks. The proposed features are computed
using alternative frequency-warping technique and formant-specific block
transformation of filter bank log energies. We have evaluated existing and
proposed features against several kinds of synthetic speech data from ASVspoof
2015 corpora. The results show that the proposed techniques outperform existing
approaches for various spoofing attack detection task. The techniques
investigated in this paper can also accurately classify natural and synthetic
speech as equal error rates (EERs) of 0% have been achieved.


title: Dynamic Scene Deblurring using a Locally Adaptive Linear Blur Model

abstract:
  State-of-the-art video deblurring methods cannot handle blurry videos
recorded in dynamic scenes, since they are built under a strong assumption that
the captured scenes are static. Contrary to the existing methods, we propose a
video deblurring algorithm that can deal with general blurs inherent in dynamic
scenes. To handle general and locally varying blurs caused by various sources,
such as moving objects, camera shake, depth variation, and defocus, we estimate
pixel-wise non-uniform blur kernels. We infer bidirectional optical flows to
handle motion blurs, and also estimate Gaussian blur maps to remove optical
blur from defocus in our new blur model. Therefore, we propose a single energy
model that jointly estimates optical flows, defocus blur maps and latent
frames. We also provide a framework and efficient solvers to minimize the
proposed energy model. By optimizing the energy model, we achieve significant
improvements in removing general blurs, estimating optical flows, and extending
depth-of-field in blurry frames. Moreover, in this work, to evaluate the
performance of non-uniform deblurring methods objectively, we have constructed
a new realistic dataset with ground truths. In addition, extensive experimental
on publicly available challenging video data demonstrate that the proposed
method produces qualitatively superior performance than the state-of-the-art
methods which often fail in either deblurring or optical flow estimation.


title: Cops and Robbers ordinals of cop-win trees

abstract:
  A relational characterization of cop-win graphs was provided by Nowakowski
and Winkler in their seminal paper on the game of Cops and Robbers. As a
by-product of that characterization, each cop-win graph is assigned a unique
ordinal, which we refer to as a CR-ordinal. For finite graphs, CR-ordinals
correspond to the length of the game assuming optimal play, with the cop
beginning the game in a least favourable initial position. For infinite graphs,
however, the possible values of CR-ordinals have not been considered in the
literature until the present work. We classify the CR-ordinals of cop-win trees
as either a finite ordinal, or those of the form $\alpha + \omega$, where
$\alpha$ is a limit ordinal. For general infinite cop-win graphs, we provide an
example whose CR-ordinal is not of this form. We finish with some problems on
characterizing the CR-ordinals in the general case of cop-win graphs.


title: Improving Urban Mobility by Understanding its Complexity

abstract:
  Urban mobility systems are composed multiple elements with strong
interactions, i.e. their future is co-determined by the state of other
elements. Thus, studying components in isolation, i.e. using a reductionist
approach, is inappropriate. I propose five recommendations to improve urban
mobility based on insights from the scientific study of complex systems: use
adaptation over prediction, regulate interactions to avoid friction, use
sensors to recover real time information, develop adaptive algorithms to
exploit that information, and deploy agents to act on the urban environment.


title:
Structure coefficients for Jack characters: approximate factorization
  property

abstract:
  Jack characters are a generalization of the characters of the symmetric
groups; a generalization that is related to Jack symmetric functions. We
investigate the structure coefficients for Jack characters; they are a
generalization of the connection coefficients for the symmetric groups. More
specifically, we study the cumulants which measure the discrepancy between
these structure coefficients and the simplistic structure coefficients related
to the disjoint product. We show that Jack characters satisfy approximate
factorization property: their cumulants are of very small degree and the
character related to a given partition is approximately equal to the product of
the characters related to its parts. This result will play a key role in the
proof of Gaussianity of fluctuations for a class of random Young diagrams
related to the Jack polynomials.


title:
Influence of Fr\"ohlich polaron coupling on renormalized electron bands
  in polar semiconductors. Results for zincblende GaN

abstract:
  \ni We develop a simple method to study the zero-point and thermally
renormalized electron energy $\varepsilon_{\mathbf{k}n}(T)$ for $\mathbf{k}n$
the conduction band minimum or valence maximum in polar semiconductors. We use
the adiabatic approximation, including an imaginary broadening parameter
$i\delta$ to supress noise in the density-functional integrations. Fr\"{o}hlich
polaron methods provide analytic expressions for the contribution of the
problematic optical phonon mode. We use this to correct the renormalization
obtained from the adiabatic approximation. Test calculations are done for
zincblende GaN for an 18x18x18 integration grid. The Fr\"ohlich correction is
of order -0.02 eV for the zero-point energy shift of the conduction band
minimum, and +0.03 eV for the valence band maximum; the correction to
renormalization of the 3.28 eV gap is -0.05 eV, a significant fraction of the
total zero point renormalization of -0.15 eV.


title:
Wellposedness and decay rates for the Cauchy problem of the
  Moore-Gibson-Thompson equation arising in high intensity ultrasound

abstract:
  In this paper, we study the Moore--Gibson--Thompson equation in
$\mathbb{R}^N$, which is a third order in time equation that arises in viscous
thermally relaxing fluids and also in viscoelastic materials (then under the
name of \emph{standard linear viscoelastic} model). First, we use some Lyapunov
functionals in the Fourier space to show that, under certain assumptions on
some parameters in the equation, an energy norm related with the solution
decays with a rate $(1+t)^{-N/4}$. But this does not give the decay rate of the
solution itself. Hence, in the second part of the paper, we show an explicit
representation of the solution in the frequency domain by analyzing the
eigenvalues of the Fourier image of the solution and writing the solution
accordingly. We use this eigenvalues expansion method to give the decay rate of
the solution (and its derivatives), which (for the solution) results in
$(1+t)^{1-N/4}$ for $N=1,2$ and $(1+t)^{1/2-N/4}$ when $N\geq 3$.


title: Saturation of repeated quantum measurements

abstract:
  We study sequential measurement scenarios where the system is repeatedly
subjected to the same measurement process. We first provide examples of such
repeated measurements where further repetitions of the measurement do not
increase our knowledge on the system after some finite number of measurement
steps. We also prove, however, that repeating the L\"uders measurement of an
unsharp two-outcome observable never saturates in this sense, and we
characterize the observable measured in the limit of infinitely many
repetitions. Our result implies that a repeated measurement can be used to
correct the inherent noise of an unsharp observable.


title:
Microscopic Statistical Characterisation of the Congested Traffic Flow
  and Some Salient Empirical Features

abstract:
  We present large scale and detailed analysis of the microscopic empirical
data of the traffic flow, focusing on the non-linear interactions between the
vehicles when the traffic is congested. By implementing a "renormalisation"
procedure that averages over relatively unimportant factors, we extract the
effective dependence of the acceleration on the vehicle headway, velocity and
relative velocity, that characterises not just a few vehicles but the traffic
system as a whole. Several interesting features of the detailed
vehicle-to-vehicle interactions are revealed, including the stochastic
distribution of human responses, relative importance of non-linear terms in
different density regimes, symmetric response to the relative velocity, and the
insensitivity of the acceleration to the velocity within a certain headway and
velocity range. The latter leads to a multitude of steady-states without a
fundamental diagram, showing strong evidence of the "synchronised phase",
substantiated with additional microscopic details. We discuss the richness of
the available data for the understanding of the human driving behaviours, and
its usefulness in construction and calibration of both deterministic and
stochastic microscopic traffic models.


title: How many quasiparticles can be in a superconductor?

abstract:
  Experimentally and mysteriously, the concentration of quasiparticles in a
gapped superconductor at low temperatures always by far exceeds its equilibrium
value. We study the dynamics of localized quasiparticles in superconductors
with a spatially fluctuating gap edge. The competition between phonon-induced
quasiparticle recombination and generation by a weak non-equilibrium agent
results in an upper bound for the concentration that explains the mystery.


title: Comparisons of Black Hole Entropy

abstract:
  In this thesis I examine several different concepts of black hole entropy in
order to understand whether they describe the same quantity. I look at
statistical and entanglement entropies, Wald entropy and Carlip's entropy from
conformal field theory, and compare their behavior in a few specific aspects:
divergence at the BH horizon, dependence on space time curvature and behavior
under a geometric variation. I find that statistical and entanglement entropy
may be similar but they seem to differ from the entropy of Wald and Carlip.
Chapters 2 and 3 overlap with 1010.4157 and 1310.3938. Chapter 4 does not
appear elsewhere.


title:
A singular, admissible extension which splits algebraically, but not
  strongly, of the algebra of bounded operators on a Banach space

abstract:
  Let $E$ be the Banach space constructed by Read (J. London Math. Soc. 1989)
such that the Banach algebra $\mathscr{B}(E)$ of bounded operators on $E$
admits a discontinuous derivation. We show that $\mathscr{B}(E)$ has a
singular, admissible extension which splits algebraically, but does not split
strongly. This answers a natural question going back to the work of Bade,
Dales, and Lykova (Mem. Amer. Math. Soc. 1999), and complements recent results
of Laustsen and Skillicorn (C. R. Math. Acad. Sci. Paris, to appear).


title: Efficient Generation of Inductive Validity Cores for Safety Properties

abstract:
  Symbolic model checkers can construct proofs of properties over very complex
models. However, the results reported by the tool when a proof succeeds do not
generally provide much insight to the user. It is often useful for users to
have traceability information related to the proof: which portions of the model
were necessary to construct it. This traceability information can be used to
diagnose a variety of modeling problems such as overconstrained axioms and
underconstrained properties, and can also be used to measure completeness of a
set of requirements over a model. In this paper, we present a new algorithm to
efficiently compute the inductive validity core (IVC) within a model necessary
for inductive proofs of safety properties for sequential systems. The algorithm
is based on the UNSAT core support built into current SMT solvers and a novel
encoding of the inductive problem to try to generate a minimal inductive
validity core. We prove our algorithm is correct, and describe its
implementation in the JKind model checker for Lustre models. We then present an
experiment in which we benchmark the algorithm in terms of speed, diversity of
produced cores, and minimality, with promising results.


title: Complex interpolation of variable Triebel-Lizorkin spaces

abstract:
  We study complex interpolation of variable Triebel-Lizorkin spaces,
especially we present the complex interpolation of $F_{p(\cdot),q}^{\alpha }$
and $F_{p(\cdot ),p(\cdot )}^{\alpha (\cdot )}$ spaces. Also, some limiting
cases are given.


title: Theoretical spectroscopy of quasars within Karlsson's law

abstract:
  The law introduced by Karlsson in spectroscopy of low-redshift quasars
involves the Lyman spectrum of hydrogen atoms. Thus, it appears necessary to
study the concepts introduced by a standard spectroscopy of quasars, studied
here, with those deducted from $\Lambda$-CDM.A visible absorption of a sharp
and saturated spectral line in a gas requires a long path without perturbations
as collisions or cosmological redshift. Spectra of absorbed, saturated lines of
quasars obeying Karlsson's law mainly result from interactions of natural,
thermal light radiated by quasar with relatively cold, low presure atomic
hydrogen. These lines are produced by three processes: a) A conventional
absorption in a relatively cold gas produces a set of lines; b) These lines are
multiplied by absorption after fundamental 3K or 4K redshifts, where K is
Karlsson's constant: Spectra show that redshifts 3K (or 4K) exactly bring
absorbed Lyman beta (or gamma) line on Lyman alpha: redshift almost disappears,
and gas lines are intensely absorbed in the absence of alpha absorption; c)
Redshifts occur in regions where light at alpha frequency is poorly absorbed
due to permanent redshift, except when excitation of hydrogen to 2P level is
sufficient for a superradiant flash emission at alpha frequency. This causes an
intense absorption of high radiance rays from quasar, so the absorption of a
line at current Lyman alpha frequency. Lightning and pumping produce relaxation
oscillations that write many absorption lines. Redshifts by H atoms in 2P
levels are due to parametric interactions composed of Impulsive Stimulated
Raman Scatterings (ISRS): excited hydrogen atoms catalyze energy exchanges
between observed ray and background cold thermal radiation, in agreement with
thermodynamics. Description of Universe becomes much simpler, but less
marvelous.


title: Non-symmetric polarization

abstract:
  Let $P$ be an $m$-homogeneous polynomial in $n$-complex variables $x_1,
\dotsc, x_n$. Clearly, $P$ has a unique representation in the form
\begin{equation*} P(x)= \sum_{1 \leq j_1 \leq \dotsc \leq j_m \leq n} c_{(j_1,
\dotsc, j_m)} \, x_{j_1} \dotsb x_{j_m} \,, \end{equation*} and the $m$"~form
\begin{equation*} L_P(x^{(1)}, \dotsc, x^{(m)})= \sum_{1 \leq j_1 \leq \dotsc
\leq j_m \leq n} c_{(j_1, \dotsc, j_m)} \, x^{(1)}_{j_1} \dotsb x^{(m)}_{j_m}
\end{equation*} satisfies $L_P(x,\dotsc, x) = P(x)$ for every
$x\in\mathbb{C}^n$. We show that, although $L_P$ in general is non-symmetric,
for a large class of reasonable norms $ \lVert \cdot \rVert $ on $\mathbb{C}^n$
the norm of $L_P$ on $(\mathbb{C}^n, \lVert \cdot \rVert )^m$ up to a
logarithmic term $(c \log n)^{m^2}$ can be estimated by the norm of $P$ on $
(\mathbb{C}^n, \lVert \cdot \rVert )$; here $c \ge 1$ denotes a universal
constant. Moreover, for the $\ell_p$"~norms $ \lVert \cdot \rVert_p$, $1 \leq p
< 2$ the logarithmic term in the number $n$ of variables is even superfluous.


title: 5-regular oriented graphs with optimum skew energy

abstract:
  Let $G$ be a simple undirected graph and $G^\sigma$ be the corresponding
oriented graph of $G$ with the orientation $\sigma$. The skew energy of
$G^\sigma$, denoted by $\varepsilon_s(G^\sigma)$, is defined as the sum of the
singular values of the skew adjacency matrix $S(G^\sigma)$. In 2010, Adiga et
al. certified that $\varepsilon_s(G^\sigma) \leq n\sqrt{\Delta}$, where
$\Delta$ is the maximum degree of $G$ of order $n$. In this paper, we determine
all connected 5-regular oriented graphs of order $n$ with maximum skew-energy.


title: Theory of spin loss at metallic interfaces

abstract:
  Interfacial spin-flip scattering plays an important role in magnetoelectronic
devices. Spin loss at metallic interfaces is usually quantified by matching the
magnetoresistance data for multilayers to the Valet-Fert model, while treating
each interface as a fictitious bulk layer whose thickness is $\delta$ times the
spin-diffusion length. By employing the properly generalized circuit theory and
the scattering matrix approaches, we derive the relation of the parameter
$\delta$ to the spin-flip transmission and reflection probabilities at an
individual interface. It is found that $\delta$ is proportional to the square
root of the probability of spin-flip scattering. We calculate the spin-flip
transmission probability for flat and rough Cu/Pd interfaces using the
Landauer-B\"uttiker method based on the first-principles electronic structure
and find $\delta$ in reasonable agreement with experiment.


title:
Solar r-process-constrained actinide production in neutrino-driven winds
  of supernovae

abstract:
  Long-lived radioactive nuclei play an important role as
nucleo-cosmochronometers and as cosmic tracers of nucleosynthetic source
activity. In particular nuclei in the actinide region like thorium, uranium,
and plutonium can testify to the enrichment of an environment by the still
enigmatic astrophysical sources that are responsible for the production of
neutron-rich nuclei by the rapid neutron-capture process (r-process).
Supernovae and merging neutron-star (NS) or NS-black hole binaries are
considered as most likely sources of the r-nuclei. But arguments in favour of
one or the other or both are indirect and make use of assumptions; they are
based on theoretical models with remaining simplifications and shortcomings. An
unambiguous observational determination of a production event is still missing.
In order to facilitate searches in this direction, e.g.\ by looking for
radioactive tracers in stellar envelopes, the interstellar medium or
terrestrial reservoirs, we provide improved theoretical estimates and
corresponding uncertainty ranges for the actinide production ($^{232}$Th,
$^{235,236,238}$U, $^{237}$Np, $^{244}$Pu, and $^{247}$Cm) in neutrino-driven
winds of core-collapse supernovae. Since state-of-the-art supernova models do
not yield r-process viable conditions ---but still lack, for example, the
effects of strong magnetic fields--- we base our investigation on a simple
analytical, Newtonian, adiabatic and steady-state wind model and consider the
superposition of a large number of contributing components, whose
nucleosynthesis-relevant parameters (mass weight, entropy, expansion time
scale, and neutron excess) are constrained by the assumption that the
integrated wind nucleosynthesis closely reproduces the solar system
distribution of r-process elements. We also test the influence of uncertain
nuclear physics.


title: Universal probability-free prediction

abstract:
  We construct universal prediction systems in the spirit of Popper's
falsifiability and Kolmogorov complexity and randomness. These prediction
systems do not depend on any statistical assumptions (but under the IID
assumption they dominate, to within the usual accuracy, conformal prediction).
Our constructions give rise to a theory of algorithmic complexity and
randomness of time containing analogues of several notions and results of the
classical theory of Kolmogorov complexity and randomness.


title: Symmetric Kronecker products and semiclassical wave packets

abstract:
  We investigate the iterated Kronecker product of a square matrix with itself
and prove an invariance property for symmetric subspaces. This motivates the
definition of an iterated symmetric Kronecker product and the derivation of an
explicit formula for its action on vectors. We apply our result for describing
a linear change in the matrix parametrization of semiclassical wave packets.


title:
Summation Theory II: Characterizations of
  $\boldsymbol{R\Pi\Sigma^*}$-extensions and algorithmic aspects

abstract:
  Recently, $R\Pi\Sigma^*$-extensions have been introduced which extend Karr's
$\Pi\Sigma^*$-fields substantially: one can represent expressions not only in
terms of transcendental sums and products, but one can work also with products
over primitive roots of unity. Since one can solve the parameterized
telescoping problem in such rings, covering as special cases the summation
paradigms of telescoping and creative telescoping, one obtains a rather
flexible toolbox for symbolic summation. This article is the continuation of
this work. Inspired by Singer's Galois theory of difference equations we will
work out several alternative characterizations of $R\Pi\Sigma^*$-extensions:
adjoining naively sums and products leads to an $R\Pi\Sigma^*$-extension iff
the obtained difference ring is simple iff the ring can be embedded into the
ring of sequences iff the ring can be given by the interlacing of
$\Pi\Sigma^*$-extensions. From the viewpoint of applications this leads to a
fully automatic machinery to represent indefinite nested sums and products in
such $R\Pi\Sigma^*$-rings. In addition, we work out how the parameterized
telescoping paradigm can be used to prove algebraic independence of indefinite
nested sums. Furthermore, one obtains an alternative reduction tactic to solve
the parameterized telescoping problem in basic $R\Pi\Sigma^*$-extensions
exploiting the interlacing property.


title:
The evolution of complete non-compact graphs by powers of Gauss
  curvature

abstract:
  We study the evolution of convex complete non-compact graphs by positive
powers of Gauss curvature. We show that if the initial complete graph has a
local uniform convexity, then the graph evolves by any positive power of Gauss
curvature for all time. In particular, the initial graph is not necessarily
differentiable.


title:
Mining Valence, Arousal, and Dominance - Possibilities for Detecting
  Burnout and Productivity?

abstract:
  Similar to other industries, the software engineering domain is plagued by
psychological diseases such as burnout, which lead developers to lose interest,
exhibit lower activity and/or feel powerless. Prevention is essential for such
diseases, which in turn requires early identification of symptoms. The
emotional dimensions of Valence, Arousal and Dominance (VAD) are able to derive
a person's interest (attraction), level of activation and perceived level of
control for a particular situation from textual communication, such as emails.
As an initial step towards identifying symptoms of productivity loss in
software engineering, this paper explores the VAD metrics and their properties
on 700,000 Jira issue reports containing over 2,000,000 comments, since issue
reports keep track of a developer's progress on addressing bugs or new
features. Using a general-purpose lexicon of 14,000 English words with known
VAD scores, our results show that issue reports of different type (e.g.,
Feature Request vs. Bug) have a fair variation of Valence, while increase in
issue priority (e.g., from Minor to Critical) typically increases Arousal.
Furthermore, we show that as an issue's resolution time increases, so does the
arousal of the individual the issue is assigned to. Finally, the resolution of
an issue increases valence, especially for the issue Reporter and for quickly
addressed issues. The existence of such relations between VAD and issue report
activities shows promise that text mining in the future could offer an
alternative way for work health assessment surveys.


title:
Constructive method for detecting the information backflow of bijective
  non-completely-positive-divisible dynamics

abstract:
  We investigate the relation between two approaches to the characterisation of
quantum Markovianity, divisibility and lack of information backflow. We show
that a bijective dynamical map is completely-positive-divisible if and only if
a monotonic non-increase of distinguishability is observed for two equiprobable
states of the evolving system and an ancilla. Moreover our proof is
constructive: given any such map that is not completely-positive-divisible, we
give an explicit construction of two states that, when taken with the same a
priori probability, exhibit information back-flow. Finally, while an ancilla is
necessary for the equivalence to hold in general, we show that it is always
possible to witness the non-Markovianity of bijective maps without using any
entanglement between system and ancilla.


title: The Galois coaction on $\phi^4$ periods

abstract:
  We report on calculations of Feynman periods of primitive log-divergent
$\phi^4$ graphs up to eleven loops. The structure of $\phi^4$ periods is
described by a series of conjectures. In particular, we discuss the possibility
that $\phi^4$ periods are a comodule under the Galois coaction. Finally, we
compare the results with the periods of primitive log-divergent non-$\phi^4$
graphs up to eight loops and find remarkable differences to $\phi^4$ periods.
Explicit results for all periods we could compute are provided in ancillary
files.


title: Secrecy Sum Rate Maximization in Non-Orthogonal Multiple Access

abstract:
  Non-orthogonal multiple access (NOMA) has been recognized as a promising
technique for providing high data rates in 5G systems. This letter is to study
physical layer security in a single-input single-output (SISO) NOMA system
consisting of a transmitter, multiple legitimate users and an eavesdropper. The
aim of this letter is to maximize the secrecy sum rate (SSR) of the NOMA system
subject to the users' quality of service (QoS) requirements. We firstly
identify the feasible region of the transmit power for satisfying all users'
QoS requirements. Then we derive the closed-form expression of an optimal power
allocation policy that maximizes the SSR. Numerical results are provided to
show a significant SSR improvement by NOMA compared with conventional
orthogonal multiple access (OMA).


title: Extending the LCDM model through shear-free anisotropies

abstract:
  If the spacetime metric has anisotropic spatial curvature, one can afford to
expand the universe isotropically, provided that the energy-momentum tensor
satisfy a certain con- straint. This leads to the so-called shear-free metrics,
which have the interesting property of violating the cosmological principle
while still preserving the isotropy of the cosmic mi- crowave background (CMB)
radiation. In this work we show that shear-free cosmologies correspond to an
attractor solution in the space of models with anisotropic spatial curva- ture.
Through a rigorous definition of linear perturbation theory in these
spacetimes, we show that shear-free models represent a viable alternative to
describe the large-scale evo- lution of the universe, leading, in particular,
to a kinematically equivalent Sachs-Wolfe effect. Alternatively, we discuss
some specific signatures that shear-free models would imprint on the
temperature spectrum of CMB.


title: A linear algorithm for Brick Wang tiling

abstract:
  The Wang tiling is a classical problem in combinatorics. A major theoretical
question is to find a (small) set of tiles which tiles the plane only
aperiodically. In this case, resulting tilings are rather restrictive. On the
other hand, Wang tiles are used as a tool to generate textures and patterns in
computer graphics. In these applications, a set of tiles is normally chosen so
that it tiles the plane or its sub-regions easily in many different ways. With
computer graphics applications in mind, we introduce a class of such tileset,
which we call sequentially permissive tilesets, and consider tiling problems
with constrained boundary. We apply our methodology to a special set of Wang
tiles, called Brick Wang tiles, introduced by Derouet-Jourdan et al. in 2015 to
model wall patterns. We generalise their result by providing a linear algorithm
to decide and solve the tiling problem for arbitrary planar regions with holes.


title: A reduction theorem for $\tau$-rigid modules

abstract:
  We prove a theorem which gives a bijection between the support $\tau$-tilting
modules over a given finite-dimensional algebra $A$ and the support
$\tau$-tilting modules over $A/I$, where $I$ is the ideal generated by the
intersection of the center of $A$ and the radical of $A$. This bijection is
both explicit and well-behaved. We give various corollaries of this, with a
particular focus on blocks of group rings of finite groups. In particular we
show that there are $\tau$-tilting finite wild blocks with more than one simple
module. We then go on to classify all support $\tau$-tilting modules for all
algebras of dihedral, semidihedral and quaternion type, as defined by Erdmann,
which include all tame blocks of group rings. Note that since these algebras
are symmetric, this is the same as classifying all basic two-term tilting
complexes, and it turns out that a tame block has at most $32$ different basic
two-term tilting complexes. We do this by using the aforementioned reduction
theorem, which reduces the problem to ten different algebras only depending on
the ground field $k$, all of which happen to be string algebras. To deal with
these ten algebras we give a combinatorial classification of all $\tau$-rigid
modules over (not necessarily symmetric) string algebras.


title: NGC 5195 in M51: Feedback `Burps' after a Massive Meal?

abstract:
  We describe a double-arc-like X-ray structure lying ~15-30" (~0.8-1.7 kpc)
south of the NGC 5195 nucleus visible in the merged exposures of long Chandra
pointings of M51. The curvature and orientation of the arcs argues for a
nuclear origin. The arcs are radially separated by ~15" (~1$ kpc), but are
rotated relative to each other by ~30 deg. From an archival image, we find a
slender Halpha-emitting region just outside the outer edge of the outer X-ray
arc, suggesting that the X-ray-emitting gas plowed up and displaced the
Halpha-emitting material from the galaxy core. Star formation may have
commenced in that arc. Halpha emission is present at the inner arc, but appears
more complex in structure. In contrast to an explosion expected to be
azimuthally symmetric, the X-ray arcs suggest a focused outflow. We interpret
the arcs as episodic outbursts from the central super-massive black hole
(SMBH). We conclude that NGC 5195 represents the nearest galaxy exhibiting
on-going, large-scale outflows of gas, in particular, two episodes of a focused
outburst of the SMBH. The arcs represent a clear demonstration of feedback.


title:
Photoluminescence excitation and spectral hole burning spectroscopy of
  silicon vacancy centers in diamond

abstract:
  Silicon-vacancy (SiV) centers in diamond are promising systems for quantum
information applications due to their bright single photon emission and
optically accessible spin states. Furthermore, SiV centers in low-strain
diamond are insensitive to pertubations of the dielectric environment, i.e.
they show very weak spectral diffusion. This property renders ensembles of SiV
centers interesting for sensing applications. We here report on
photoluminescence excitation (PLE) spectroscopy on an SiV ensemble in a low
strain, CVD-grown high quality diamond layer, where we measure the fine
structure with high resolution and obtain the linewidths and splittings of the
SiV centers. We investigate the temperature dependence of the width and
position of the fine structure peaks. Our measurements reveal linewidths of
about 10 GHz as compared to a lifetime limited width on the order of 0.1 GHz.
This difference arises from the inhomogeneous broadening of the transitions
caused by residual strain. To overcome inhomogeneous broadening we use spectral
hole burning spectroscopy which enables us to measure a nearly lifetime limited
homogeneous linewidth of 279 MHz. Furthermore, we demonstrate evidence of
coherent interaction in the system by driving a $\Lambda$-scheme. Additional
measurements on single emitters created by ion implantation confirm the
homogeneous linewidths seen in the spectral hole burning experiments and relate
the ground state splitting to the decoherence rate.


title:
Confinement effects in ultra-thin ZnO polymorph films: electronic and
  optical properties

abstract:
  Relying on generalized-gradient and hybrid first-principles simulations, this
work provides a complete characterization of the electronic properties of ZnO
ultra-thin films, cut along the Body-Centered-Tetragonal(010), Cubane(100),
h-BN(0001), Zinc-Blende(110), Wurtzite(10$\bar{1}$0) and (0001) orientations.
The characteristics of the local densities of states are analyzed in terms of
the reduction of the Madelung potential on under-coordinated atoms and surface
states/resonances appearing at the top of the VB and bottom of the CB. The gap
width in the films is found to be larger than in the corresponding bulks, which
is assigned to quantum confinement effects. The components of the high
frequency dielectric constant are determined and the absorption spectra of the
films are computed. They display specific features just above the absorption
threshold due to transitions from or to the surface resonances. This study
provides a first understanding of finite size effects on the electronic
properties of ZnO thin films and a benchmark which is expected to foster
experimental characterization of ultra-thin films via spectroscopic techniques.


title: A note on Hilbert-Kunz multiplicity

abstract:
  In this note we first give a new bound on $e_{HK}(\sim)$ the Hilbert-Kunz
multiplicity of invariant rings, by the help of the Noether's bound. Then, we
simplify, extend and present applications of the reciprocity formulae due to L.
Smith. He proved the formula over polynomial rings and his result is tight in
the following sense: Over complete intersection rings with isolated singularity
we show that the reciprocity formulae "$e_{HK}(R/I)+ e_{HK}(R/J) =
e_{HK}(R/\underline{f})$" is equivalent with $\pd(I)<\infty$ when $I$ is an
$\fm$-primary unmixed ideal linked to $J$ along with a regular sequence
$\underline{f}$.


title: An Effectful Treatment of Dependent Types

abstract:
  We extend Levy's call-by-push-value (CBPV) analysis from simple to dependent
type theory (DTT) in order to study the interaction between computational
effects and dependent types. We define the naive system of dependently typed
CBPV, dCBPV-, and its extension with a principle of Kleisli extensions for
dependent functions, dCBPV+. We investigate these systems from the points of
view of syntax, categorical semantics, concrete models and operational
semantics, in presence of a range of effects. We observe that, while the
expressive power of dCBPV+ is needed if we want well-defined call-by-value
(CBV) and call-by-name (CBN) translations of DTT, it is a less straightforward
system than dCBPV-, in presence of some effects. Indeed, to be able to
construct specific models and to retain the subject reduction property in the
operational semantics, we are required to impose certain subtyping conditions,
the idea being that the type of a computation may only become more (not less)
specified as certain effects are executed.


title: Frozen Fronts Selection in flow against self-sustained chemical waves

abstract:
  Autocatalytic reaction fronts between two reacting species in the absence of
fluid flow, propagate as solitary waves. The coupling between autocatalytic
reaction front and forced hydrodynamic flow may lead to stationary front whose
velocity and shape depend on the underlying flow field. We focus on the issue
of the chemo-hydrodynamic coupling between forced advection opposed to
self-sustained chemical waves which can lead to static stationary fronts, i.e
Frozen Fronts, $FF$. Towards that purpose, we perform experiments, analytical
computations and numerical simulations with the autocatalytic Iodate Arsenious
Acid reaction ($IAA$) over a wide range of flow velocities around a solid disk.
For the same set of control parameters, we observe two types of frozen fronts:
an upstream $FF$ which avoid the solid disk and a downstream $FF$ with two
symmetric branches emerging from the solid disk surface. We delineate the range
over which we do observe these Frozen Fronts. We also address the relevance of
the so-called eikonal, thin front limit to describe the observed fronts and
select the frozen front shapes.


title:
Probabilistic Estimates of the Maximum Norm of Random Neumann Fourier
  Series

abstract:
  We study the maximum norm behavior of $L^2$-normalized random Fourier cosine
series with a prescribed large wave number. Precise bounds of this type are an
important technical tool in estimates for spinodal decomposition, the
celebrated phase separation phenomenon in metal alloys. We derive rigorous
asymptotic results as the wave number converges to infinity, and shed light on
the behavior of the maximum norm for medium range wave numbers through
numerical simulations. Finally, we develop a simplified model for describing
the magnitude of extremal values of random Neumann Fourier series. The model
describes key features of the development of maxima and can be used to predict
them. This is achieved by decoupling magnitude and sign distribution, where the
latter plays an important role for the study of the size of the maximum norm.
Since we are considering series with Neumann boundary conditions, particular
care has to be placed on understanding the behavior of the random sums at the
boundary.


title:
On the second smallest and the largest normalized Laplacian eigenvalues
  of a graph

abstract:
  Let $G$ be a simple connected graph with order $n$. Let $\mathcal{L}(G)$ be
the normalized Laplacian matrix of $G$. Let $\lambda_{k}(G)$ be the $k$-th
smallest normalized Laplacian eigenvalue of $G$. Denote $\rho(A)$ the spectral
radius of the matrix $A$. In this paper, we study the behaviors of
$\lambda_{2}(G)$ and $\rho(\mathcal{L}(G))$ when the graph is perturbed by
three operations.


title: CO-to-H_2 Conversion Factor of Molecular Clouds using X-Ray Shadows

abstract:
  A new method to determine the CO-to-H$_2$ conversion factor $X_{\rm CO}$
using absorption of diffuse X-ray emission by local molecular clouds was
developed. It was applied to the Ophiucus (G353+17) and Corona Australis
(G359-18) clouds using CO-line and soft X-ray archival data. We obtained a
value $X_{\rm CO} =1.85 \pm 0.45 \times 10^{20} {\rm H_2 cm^{-2}/(K~ km~
s^{-1})}$ as the average of least-$chi^2$ fitting results for R4 (0.7 keV) and
R5 (0.8 keV) bands.
  Full resolution pdf available at
http://www.ioa.s.u-tokyo.ac.jp/~sofue/htdocs/2016Xco/


title: Frame-dragging Effect in Strong Gravity Regime

abstract:
  The exact frame-dragging (or Lense-Thirring (LT) precession) rates for Kerr,
Kerr-Taub-NUT (KTN) and Taub-NUT spacetimes have been derived. Remarkably, in
the case of the `zero angular momentum' Taub-NUT spacetime, the frame-dragging
effect is shown not to vanish, when considered for spinning test gyroscope. In
the case of the interior of the pulsars, the exact frame-dragging rate
monotonically decreases from the center to the surface along the pole and but
it shows an `anomaly' along the equator. Moving from the equator to the pole,
it is observed that this `anomaly' disappears after crossing a critical angle.
The `same' anomaly can also be found in the KTN spacetime. The resemblance of
the anomalous LT precessions in the KTN spacetimes and the spacetime of the
pulsars could be used to identify a role of Taub-NUT solutions in the
astrophysical observations or equivalently, a signature of the existence of NUT
charge in the pulsars.


title:
The effect of superfluid hydrodynamics on pulsar glitch sizes and
  waiting times

abstract:
  Pulsar glitches, sudden jumps in frequency observed in many radio pulsars,
may be the macroscopic manifestation of superfluid vortex avalanches on the
microscopic scale. Small scale quantum mechanical simulations of vortex motion
in a decelerating container have shown that such events are possible and
predict power-law distributions for the size of the events, and exponential
distributions for the waiting time. Despite a paucity of data, this prediction
is consistent with the size and waiting time distributions of most glitching
pulsars. Nevertheless a few object appear to glitch quasi-periodically, and
exhibit many large glitches, while a recent study of the Crab pulsar has
suggested a cut-off deviations from a power-law distribution for smaller
glitches. In this paper we incorporate the results of quantum mechanical
simulations in a macroscopic scale superfluid hydrodynamics simulation. We show
that the effect of vortex coupling to the neutron and proton fluids in the
neutron star naturally leads to deviations from power-law distributions for
sizes and from exponential distributions for waiting times. In particular we
predict a cut-off in the size distribution for small glitches.


title: Optimal Control of the Thermistor Problem in Three Spatial Dimensions

abstract:
  This paper is concerned with the state-constrained optimal control of the
three-dimensional thermistor problem, a fully quasilinear coupled system of a
parabolic and elliptic PDE with mixed boundary conditions. This system models
the heating of a conducting material by means of direct current. Local
existence, uniqueness and continuity for the state system are derived by
employing maximal parabolic regularity in the fundamental theorem of Pr\"uss.
Global solutions are addressed, which includes analysis of the linearized state
system via maximal parabolic regularity, and existence of optimal controls is
shown if the temperature gradient is under control. The adjoint system
involving measures is investigated using a duality argument. These results
allow to derive first-order necessary conditions for the optimal control
problem in form of a qualified optimality system. The theoretical findings are
illustrated by numerical results.


title:
Mass of the b-quark and B-decay constants from Nf=2+1+1 twisted-mass
  Lattice QCD

abstract:
  We present precise lattice computations for the b-quark mass, the quark mass
ratios mb/mc and mb/ms as well as the leptonic B-decay constants. We employ
gauge configurations with four dynamical quark flavors, up/down, strange and
charm, at three values of the lattice spacing (a ~ 0.06 - 0.09 fm) and for pion
masses as low as 210 MeV. Interpolation in the heavy quark mass to the bottom
quark point is performed using ratios of physical quantities computed at nearby
quark masses exploiting the fact that these ratios are exactly known in the
static quark mass limit. Our results are also extrapolated to the physical pion
mass and to the continuum limit and read: mb(MSbar, mb) = 4.26(10) GeV, mb/mc =
4.42(8), mb/ms = 51.4(1.4), fBs = 229(5) MeV, fB = 193(6) MeV, fBs/fB =
1.184(25) and (fBs/fB)/(fK/fpi) = 0.997(17).


title:
Linear Programming Approaches for Power Savings in Software-defined
  Networks (The Extended Version)

abstract:
  Software-defined networks have been proposed as a viable solution to decrease
the power consumption of the networking component in data center networks.
Still the question remains on which scheduling algorithms are most suited to
achieve this goal. We propose 4 different linear programming approaches that
schedule requested traffic flows on SDN switches according to different
objectives. Depending on pre-defined software quality requirements such as
delay and performance, a single variation or a combination of variations can be
selected to optimize the power saving and the performance metrics. Our
simulation results demonstrate that all our algorithm variations outperform the
shortest path scheduling algorithm, our baseline on power savings, less or more
strongly depending on the power model chosen. We show that in FatTree networks,
where switches can save up to 60% of power in sleeping mode, we can achieve 15%
minimum improvement assuming a one-to-one traffic scenario. Two of our
algorithm variations privilege performance over power saving and still provide
around 45% of the maximum achievable savings.


title: Diversity in Object Proposals

abstract:
  Current top performing object recognition systems build on object proposals
as a preprocessing step. Object proposal algorithms are designed to generate
candidate regions for generic objects, yet current approaches are limited in
capturing the vast variety of object characteristics. In this paper we analyze
the error modes of the state-of-the-art Selective Search object proposal
algorithm and suggest extensions to broaden its feature diversity in order to
mitigate its error modes. We devise an edge grouping algorithm for handling
objects without clear boundaries. To further enhance diversity, we incorporate
the Edge Boxes proposal algorithm, which is based on fundamentally different
principles than Selective Search. The combination of segmentations and edges
provides rich image information and feature diversity which is essential for
obtaining high quality object proposals for generic objects. For a preset
amount of object proposals we achieve considerably better results by using our
combination of different strategies than using any single strategy alone.


title: Order-Invariant Types and Their Applications

abstract:
  Our goal is to show that the standard model-theoretic concept of types can be
applied in the study of order-invariant properties, i.e., properties definable
in a logic in the presence of an auxiliary order relation, but not actually
dependent on that order relation. This is somewhat surprising since
order-invariant properties are more of a combinatorial rather than a logical
object. We provide two applications of this notion. One is a proof, from the
basic principles, of a theorem by Courcelle stating that over trees,
order-invariant MSO properties are expressible in MSO with counting
quantifiers. The other is an analog of the Feferman-Vaught theorem for
order-invariant properties.


title:
Experimental evidence for bulk superconductivity in pure Bismuth single
  crystal at ambient pressure

abstract:
  Bulk rhombohedral Bismuth (Bi) at ambient pressure is a semimetal and it
remains in the normal state down to 10~mK. The superconductivity (SC) in bulk
Bi is thought to be very unlikely due to extremely low carrier density. The
question of SC in Bi has remained unsolved both theoretically and
experimentally. Here, we report first ever observation of bulk SC in highly
pure Bi single crystals (99.9999\%) below 0.53~mK under ambient pressure with
an estimated critical magnetic field of 5.2~$\mu$T at 0~K. The conventional
Bardeen-Cooper-Schrieffer (BCS) theory cannot explain the observed SC in Bi,
since the adiabatic approximation of the BCS theory, $\omega_D/E_F<< 1$, does
not hold true for Bi. Bi has a multi-valley type electronic band structure and
SC in Bi could be brought about by the inter-valley electron-phonon coupling.
Such a scenario calls for new theoretical ideas to understand SC in such low
carrier systems with unusual band structure in the non-adiabatic limit,
$\omega_D/E_F \gtrsim 1$. The observation of SC in Bi makes it the lowest
carrier density superconductor surpassing the record held by doped SrTiO$_3$
for nearly 50 years.


title:
The magnetic ground state of Sr2IrO4 and implications for
  second-harmonic generation

abstract:
  The currently accepted magnetic ground state of Sr2IrO4 (the -++- state)
preserves inversion symmetry. This is at odds, though, with recent experiments
that indicate a magnetoelectric ground state, leading to the speculation that
orbital currents or more exotic magnetic multipoles might exist in this
material. Here, we analyze various magnetic configurations and demonstrate that
two of them, the magnetoelectric -+-+ state and the non-magnetoelectric ++++
state, can explain these recent second-harmonic generation (SHG) experiments,
obviating the need to invoke orbital currents. The SHG-probed magnetic order
parameter has the symmetry of a parity-breaking multipole in the -+-+ state and
of a parity-preserving multipole in the ++++ state. We speculate that either
might have been created by the laser pump used in the experiments. An
alternative is that the observed magnetic SHG signal is a surface effect. We
suggest experiments that could be performed to test these various
possibilities, and also address the important issue of the suppression of the
RXS intensity at the L2 edge.


title:
Role of scalar dibaryon and $f_0(500)$ in the isovector channel of
  low-energy neutron-proton scattering

abstract:
  We calculate the total and the differential cross section for $np$ scattering
at low energies in the isospin $I=1$ channel within the so-called extended
Linear Sigma Model. This model contains conventional (pseudo)scalar and
(axial--)vector mesons, as well as the nucleon and its chiral partner within
the mirror assignment. In order to obtain good agreement with experimental data
analysis results we need to consider two additional resonances: the lightest
scalar state $f_{0}(500)$ and a dibaryon state with quantum numbers $I=1,$
$J^{P}=0^{+}$ (also known as $^{1}S_{0}$ resonance). The resonance $f_{0}(500)$
is coupled to nucleons in a chirally invariant way through the mirror
assignment and is crucial for a qualitatively correct description of the shape
of the differential cross section. On the other hand, the dibaryon is exchanged
in the $s$--channel and is responsible of the large cross section close to
threshold. We compare our results to data analysis results performed by the
SAID program of the CNS Data Analysis Center (in the following "SAID results").


title: Interactions between unidirectional quantized vortex rings

abstract:
  We have used the vortex filament method to numerically investigate the
interactions between pairs of quantized vortex rings that are initially
traveling in the same direction but with their axes offset by a variable impact
parameter. The interaction of two circular rings of comparable radii produce
outcomes that can be categorized into four regimes, dependent only on the
impact parameter; the two rings can either miss each other on the inside or
outside, or they can reconnect leading to final states consisting of either one
or two deformed rings. The fraction of of energy went into ring deformations
and the transverse component of velocity of the rings are analyzed for each
regime. We find that rings of very similar radius only reconnect for a very
narrow range of the impact parameter, much smaller than would be expected from
geometrical cross-section alone. In contrast, when the radii of the rings are
very different, the range of impact parameters producing a reconnection is
close to the geometrical value. A second type of interaction considered is the
collision of circular rings with a highly deformed ring. This type of
interaction appears to be a productive mechanism for creating small vortex
rings. The simulations are discussed in the context of experiments on colliding
vortex rings and quantum turbulence in superfluid helium in the zero
temperature limit.


title: Gradient approximation and extremum seeking via needle variations

abstract:
  We consider a gradient approximation scheme that is based on applying needle
shaped inputs. By using ideas known from the classic proof of the Pontryagin
Maximum Principle we derive an approximation that reveals that the considered
system moves along a weighted averaged gradient. Moreover, based on the same
ideas, we give similar results for arbitrary periodic inputs. We also present a
new gradient-based optimization algorithm that is motivated by our calculations
and that can be interpreted as a combination of the heavy ball method and
Nesterov's method.


title:
Harvesting vibrational energy with liquid-bridged electrodes:
  thermodynamics in mechanically and electrically driven RC-circuits

abstract:
  We theoretically study a vibrating pair of parallel electrodes bridged by a
(deformed) liquid droplet, which is a recently developed microfluidic device to
harvest vibrational energy. The device can operate with various liquids,
including liquid metals, electrolytes, as well as ionic liquids. We numerically
solve the Young-Laplace equation for all droplet shapes during a vibration
period, from which the time-dependent capacitance follows that serves as input
for an equivalent circuit model. We first investigate two existing energy
harvesters (with a constant and a vanishing bias potential), for which we
explain an open issue related to their optimal electrode separations, which is
as small as possible or as large as possible in the two cases, respectively.
Then we propose a new engine with a time-dependent bias voltage, with which the
harvested work and the power can be increased by orders of magnitude at low
vibration frequencies and by factors 2-5 at high frequencies, where frequencies
are to be compared to the inverse RC-time of the circuit.


title: Nuclear shell structures in terms of classical periodic orbits

abstract:
  Semiclassical periodic-orbit theory (POT) is applied to the physics of
nuclear structures, with the use of a realistic nuclear mean-field model given
by the radial power-law potential. Evolution of deformed shell structures,
which are responsible for various nuclear deformations, are clearly understood
from the contribution of short classical periodic orbits (POs). Bifurcations of
short POs, which imply underlying local dynamical symmetry, play significant
role there. The effect of the spin degree of freedom is also investigated in
relevance to the pseudospin symmetry in spherical nuclei and the prolate-oblate
asymmetry in shell structures of nuclei with quadrupole-type deformations.


title:
Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D
  topological insulator

abstract:
  Topological insulators have been proposed to be best characterized as bulk
magnetoelectric materials that show response functions quantized in terms of
fundamental physical constants. Here we lower the chemical potential of
three-dimensional (3D) Bi$_2$Se$_3$ films to $\sim$ 30 meV above the Dirac
point, and probe their low-energy electrodynamic response in the presence of
magnetic fields with high-precision time-domain terahertz polarimetry. For
fields higher than 5 T, we observed quantized Faraday and Kerr rotations,
whereas the DC transport is still semi-classical. A non-trivial Berry phase
offset to these values gives evidence for axion electrodynamics and the
topological magnetoelectric effect. The time structure used in these
measurements allows a direct measure of the fine structure constant based on a
topological invariant of a solid-state system.


title: On the Brauer-Picard groups of fusion categories

abstract:
  We develop methods of computation of the Brauer-Picard groups of fusion
categories and apply them to compute such groups for several classes of fusion
categories of prime power dimension: representation categories of elementary
abelian groups with twisted associativity constraint, extra special p-groups,
and the Kac-Paljutkin Hopf algebra. We conclude that many finite groups of Lie
type occur as composition factors of the Brauer-Picard groups of pointed fusion
categories.


title:
Learning Network of Multivariate Hawkes Processes: A Time Series
  Approach

abstract:
  Learning the influence structure of multiple time series data is of great
interest to many disciplines. This paper studies the problem of recovering the
causal structure in network of multivariate linear Hawkes processes. In such
processes, the occurrence of an event in one process affects the probability of
occurrence of new events in some other processes. Thus, a natural notion of
causality exists between such processes captured by the support of the
excitation matrix. We show that the resulting causal influence network is
equivalent to the Directed Information graph (DIG) of the processes, which
encodes the causal factorization of the joint distribution of the processes.
Furthermore, we present an algorithm for learning the support of excitation
matrix (or equivalently the DIG). The performance of the algorithm is evaluated
on synthesized multivariate Hawkes networks as well as a stock market and
MemeTracker real-world dataset.


title:
Torsion points of sections of Lagrangian torus fibrations and the Chow
  ring of hyper-K\"ahler manifolds

abstract:
  Let $\phi:X\rightarrow B$ be a Lagrangian fibration on a projective
irreducible hyper-K\"ahler manifold of dimension $\leq8$. Let $M\in {\rm
Pic}\,X$ be a line bundle whose restriction to the general fiber $X_b$ of
  $\phi$ is topologically trivial. We prove that if the fibration has maximal
variation or is isotrivial, the set of points $b$ such that the restriction
  $M_{\mid X_b}$ is torsion is dense in $B$. We give an application to the Chow
ring of $X$. We prove a similar result for elliptic fibrations which gives a
toy model for the argument.


title:
Identification of the relaxation kernel in diffusion processes and
  viscoelasticity with memory via deconvolution

abstract:
  We present an algorithm for the identification of the relaxation kernel in
the theory of diffusion systems with memory (or of viscoelasticity) which is
linear, in the sense that we propose a linear Volterra integral equation of
convolution type whose solution is the relaxation kernel. The algorithm is
based on the observation of the flux through a part of the boundary of a body.


title:
Inferring Gender from Names on the Web: A Comparative Evaluation of
  Gender Detection Methods

abstract:
  Computational social scientists often harness the Web as a "societal
observatory" where data about human social behavior is collected. This data
enables novel investigations of psychological, anthropological and sociological
research questions. However, in the absence of demographic information, such as
gender, many relevant research questions cannot be addressed. To tackle this
problem, researchers often rely on automated methods to infer gender from name
information provided on the web. However, little is known about the accuracy of
existing gender-detection methods and how biased they are against certain
sub-populations. In this paper, we address this question by systematically
comparing several gender detection methods on a random sample of scientists for
whom we know their full name, their gender and the country of their workplace.
We further suggest a novel method that employs web-based image retrieval and
gender recognition in facial images in order to augment name-based approaches.
Our findings show that the performance of name-based gender detection
approaches can be biased towards countries of origin and such biases can be
reduced by combining name-based an image-based gender detection methods.


title: TaIrTe4 a ternary Type-II Weyl semi-metal

abstract:
  In metallic condensed matter systems two different types of Weyl fermions can
in principle emerge, with either a vanishing (type-I) or with a finite
(type-II) density of states at the Weyl node energy. So far only WTe2 and MoTe2
were predicted to be type-II Weyl semi-metals. Here we identify TaIrTe4 as a
third member of this family of topological semi-metals. TaIrTe4 has the
attractive feature that it hosts only four well-separated Weyl points, the
minimum imposed by symmetry. Moreover, the resulting topological surface states
- Fermi arcs connecting Weyl nodes of opposite chirality - extend to about 1/3
of the surface Brillouin zone. This large momentum-space separation is very
favorable for detecting the Fermi arcs spectroscopically and in transport
experiments.


title: Preprojective algebra structure on skew-group algebras

abstract:
  We give a class of finite subgroups $G<SL(n, k)$ for which the skew-group
algebra $k[x_1,\ldots, x_n]\#G$ does not admit the grading structure of a
higher preprojective algebra. Namely, we prove that if a finite group $G<SL(n,
k)$ is conjugate to a finite subgroup of $SL(n_1, k)\times SL(n_2, k)$, for
some $n_1, n_2\geq 1$, then the skew-group algebra $k[x_1,\ldots,x_n]\#G$ is
not Morita equivalent to a higher preprojective algebra. This is related to the
preprojective algebra structure on the tensor product of two Koszul bimodule
Calabi-Yau algebras. We prove that such an algebra cannot be endowed with a
grading structure as required for a higher preprojective algebra.
  Moreover, we construct explicitly the bound quiver of the higher
preprojective algebra over a finite-dimensional Koszul algebra of finite global
dimension. We show in addition that preprojective algebras over higher
representation-infinite Koszul algebras are derivation-quotient algebras whose
relations are given by a superpotential.


title:
Tunable light trapping and absorption enhancement with graphene ring
  arrays

abstract:
  Surface plasmon resonance (SPR) has been intensively studied and widely
employed for light trapping and absorption enhancement. In the mid-infrared and
terahertz (THz) regime, graphene supports the tunable SPR via manipulating its
Fermi energy and enhances light-matter interaction at the selective wavelength.
In this work, periodic arrays of graphene rings are proposed to introduce
tunable light trapping with good angle polarization tolerance and enhance the
absorption in the light-absorbing materials nearby to more than one order.
Moreover, the design principle here could be set as a template to achieve
multi-band plasmonic absorption enhancement by introducing more graphene
concentric rings into each unit cell. This work not only opens up new ways of
employing graphene SPR, but also leads to practical applications in
high-performance simultaneous multi-color photodetection with high efficiency
and tunable spectral selectivity.


title:
Optmized stability of a modulated driver in a plasma wakefield
  accelerator

abstract:
  We analyze the transverse stability for a configuration of multiple gaussian
bunches subject to the self-generated plasma wakefield. Through a
semi-analytical approach we first study the equilibrium configuration for the
modulated beam and then we investigate the evolution of the equilibrium
configuration due to the emittance-driven expansion of the beam front that
results in a rigid backward shift. The rear-directed shift brings the modulated
beam out of the equilibrium, with the possibility for some of the bunch
particles to be lost with a consequent deterioration of the driver. We look
therefore for the proper position of the single bunches that maximize the
stability without severely affecting the accelerating field behind the driver.
We then compare the results with 3D PIC simulations.


title:
Automatic Discrimination of Color Retinal Images using the Bag of Words
  Approach

abstract:
  Diabetic retinopathy (DR) and age related macular degeneration (ARMD) are
among the major causes of visual impairment worldwide. DR is mainly
characterized by red spots, namely microaneurysms and bright lesions,
specifically exudates whereas ARMD is mainly identified by tiny yellow or white
deposits called drusen. Since exudates might be the only manifestation of the
early diabetic retinopathy, there is an increase demand for automatic
retinopathy diagnosis. Exudates and drusen may share similar appearances, thus
discriminating between them is of interest to enhance screening performance. In
this research, we investigative the role of bag of words approach in the
automatic diagnosis of retinopathy diabetes. We proposed to use a single based
and multiple based methods for the construction of the visual dictionary by
combining the histogram of word occurrences from each dictionary and building a
single histogram. The introduced approach is evaluated for automatic diagnosis
of normal and abnormal color fundus images with bright lesions. This approach
has been implemented on 430 fundus images, including six publicly available
datasets, in addition to one local dataset. The mean accuracies reported are
97.2% and 99.77% for single based and multiple based dictionaries respectively.


title:
Precise Deviations Results for the Maxima of Some Determinantal Point
  Processes: the Upper Tail

abstract:
  We prove precise deviations results in the sense of Cram\'er and Petrov for
the upper tail of the distribution of the maximal value for a special class of
determinantal point processes that play an important role in random matrix
theory. Here we cover all three regimes of moderate, large and superlarge
deviations for which we determine the leading order description of the tail
probabilities. As a corollary of our results we identify the region within the
regime of moderate deviations for which the limiting Tracy-Widom law still
predicts the correct leading order behavior. Our proofs use that the
determinantal point process is given by the Christoffel-Darboux kernel for an
associated family of orthogonal polynomials. The necessary asymptotic
information on this kernel has mostly been obtained in [Kriecherbauer T.,
Schubert K., Sch\"uler K., Venker M., Markov Process. Related Fields 21 (2015),
639-694]. In the superlarge regime these results of do not suffice and we put
stronger assumptions on the point processes. The results of the present paper
and the relevant parts of [Kriecherbauer T., Schubert K., Sch\"uler K., Venker
M., Markov Process. Related Fields 21 (2015), 639-694] have been proved in the
dissertation [Sch\"uler K., Ph.D. Thesis, Universit\"at Bayreuth, 2015].


title: Effective Hamiltonian for protected edge states in graphene

abstract:
  Edge states in topological insulators (TIs) disperse symmetrically about one
of the time-reversal invariant momenta $\Lambda$ in the Brillouin zone (BZ)
with protected degeneracies at $\Lambda$. Commonly TIs are distinguished from
trivial insulators by the values of one or multiple topological invariants that
require an analysis of the bulk band structure across the BZ. We propose an
effective two-band Hamiltonian for the electronic states in graphene based on a
Taylor expansion of the tight-binding Hamiltonian about the time-reversal
invariant $M$ point at the edge of the BZ. This Hamiltonian provides a faithful
description of the protected edge states for both zigzag and armchair ribbons
though the concept of a BZ is not part of such an effective model. We show that
the edge states are determined by a band inversion in both reciprocal and real
space, which allows one to select $\Lambda$ for the edge states without
affecting the bulk spectrum.


title: Fast Scalable Construction of (Minimal Perfect Hash) Functions

abstract:
  Recent advances in random linear systems on finite fields have paved the way
for the construction of constant-time data structures representing static
functions and minimal perfect hash functions using less space with respect to
existing techniques. The main obstruction for any practical application of
these results is the cubic-time Gaussian elimination required to solve these
linear systems: despite they can be made very small, the computation is still
too slow to be feasible.
  In this paper we describe in detail a number of heuristics and programming
techniques to speed up the resolution of these systems by several orders of
magnitude, making the overall construction competitive with the standard and
widely used MWHC technique, which is based on hypergraph peeling. In
particular, we introduce broadword programming techniques for fast equation
manipulation and a lazy Gaussian elimination algorithm. We also describe a
number of technical improvements to the data structure which further reduce
space usage and improve lookup speed.
  Our implementation of these techniques yields a minimal perfect hash function
data structure occupying 2.24 bits per element, compared to 2.68 for MWHC-based
ones, and a static function data structure which reduces the multiplicative
overhead from 1.23 to 1.03.


title:
Topological honeycomb magnon Hall effect: A calculation of thermal Hall
  conductivity of magnetic spin excitations

abstract:
  Quite recently, magnon Hall effect of spin excitations has been observed
experimentally on the kagome and pyrochlore lattices. Thermal Hall conductivity
$\kappa^{xy}$, changes sign as a function of magnetic field or temperature on
the kagome lattice, and $\kappa^{xy}$ changes sign upon reversing the sign of
the magnetic field on the pyrochlore lattice. Motivated by these recent
exciting experimental observations, we theoretically propose a simple
realization of magnon Hall effect in a two-band model on the honeycomb lattice.
The magnon Hall effect of spin excitations arises in the usual way via the
breaking of inversion symmetry of the lattice, however, by a
next-nearest-neighbour Dzyaloshinsky-Moriya (DM) interaction. We find that
$\kappa^{xy}$ has a fixed sign for all parameter regimes considered. These
results are in contrast to the Lieb, kagome and pyrochlore lattices. We further
show that the low-temperature dependence on the magnon Hall conductivity
follows a $T^{2}$ law, as opposed to the kagome and pyrochlore lattices. These
results suggest an experimental procedure to measure thermal Hall conductivity
within a class of 2D honeycomb quantum magnets and ultracold atoms trapped in
honeycomb optical lattice.