title:
Heat kernel asymptotics on sequences of elliptically degenerating
  Riemann surfaces

abstract:
  This is the first of two articles in which we define an elliptically
degenerating family of hyperbolic Riemann surfaces and study the asymptotic
behavior of the associated spectral theory. Our study is motivated by a result
from \cite{He 83}, which Hejhal attributes to Selberg, proving spectral
accumulation for the family of Hecke triangle groups. In this article, we prove
various results regarding the asymptotic behavior of heat kernels and traces of
heat kernels for both real and complex time. In \cite{GJ 16}, we will use the
results from this article and study the asymptotic behavior of numerous
spectral functions through elliptic degeneration, including spectral counting
functions, Selberg's zeta function, Hurwitz-type zeta functions, determinants
of the Laplacian, wave kernels, spectral projections, small eigenfunctions, and
small eigenvalues. The method of proof we employ follows the template set in
previous articles which study spectral theory on degenerating families of
finite volume Riemann surfaces (\cite{HJL 95}, \cite{HJL 97}, \cite{JoLu 97a},
and \cite{JoLu 97b}) and on degenerating families of finite volume hyperbolic
three manifolds (\cite{DJ 98}). Although the types of results developed here
and in \cite{GJ 16} are similar to those in existing articles, it is necessary
to thoroughly present all details in the setting of elliptic degeneration in
order to uncover all nuances in this setting.


title: Terraces for Small Groups

abstract:
  We use heuristic algorithms to find terraces for small groups. We show that
Bailey's Conjecture (that all groups other than the non-cyclic elementary
abelian 2-groups are terraced) holds up to order 511, except possibly at orders
256 and 384. We also show that Keedwell's Conjecture (that all non-abelian
groups of order at least 10 are sequenceable) holds up to order 255, and for
the groups $A_6$, $S_6$, $PSL(2,q_1)$ and $PGL(2, q_2)$ where $q_1$ and $q_2$
are prime powers with $3 \leq q_1 \leq 11$ and $3 \leq q_2 \leq 8$. A
sequencing for a group of a given order implies the existence of a complete
latin square at that order. We show that there is a sequenceable group for each
odd order up to 555 at which there is a non-abelian group. This gives 31 new
orders at which complete latin squares are now known to exist, the smallest of
which is 63. In addition, we consider terraces with some special properties,
including constructing a directed $T_2$-terrace for the non-abelian group of
order 21 and hence a Roman-2 square of order 21 (the first known such square of
odd order). Finally we report the total number terraces and directed terraces
for groups of order at most 15.


title:
Stability of global equilibrium for the multi-species Boltzmann equation
  in $L^\infty$ settings

abstract:
  We prove the stability of global equilibrium in a multi-species mixture,
where the different species can have different masses, on the $3$-dimensional
torus. We establish stability estimates in $L^\infty_{x,v}(w)$ where $w=w(v)$
is either polynomial or exponential, with explicit threshold. Along the way we
extend recent estimates and stability results for the mono-species Boltzmann
operator not only to the multi-species case but also to more general hard
potential and Maxwellian kernels.


title: Arborified multiple zeta values

abstract:
  We describe some particular finite sums of multiple zeta values which arise
from J. Ecalle's "arborification", a process which can be described as a
surjective Hopf algebra morphism from the Hopf algebra of decorated rooted
forests onto a Hopf algebra of shuffles or quasi-shuffles. This formalism holds
for both the iterated sum picture and the iterated integral picture. It
involves a decoration of the forests by the positive integers in the first
case, by only two colours in the second case.


title: Mesoscopic eigenvalue statistics of Wigner matrices

abstract:
  We prove that the linear statistics of the eigenvalues of a Wigner matrix
converge to a universal Gaussian process on all mesoscopic spectral scales,
i.e. scales larger than the typical eigenvalue spacing and smaller than the
global extent of the spectrum.


title:
An Algorithm For The Construction of The Tight Span of Finite Subsets of
  The Manhattan Plane

abstract:
  We give a simple algorithm for the construction of the tight span of a finite
subset of the Manhattan plane.


title: A New ZrCuSiAs-Type Superconductor: ThFeAsN

abstract:
  We report the first nitrogen-containing iron-pnictide superconductor ThFeAsN,
which is synthesized by a solid-state reaction in an evacuated container. The
compound crystallizes in a ZrCuSiAs-type structure with the space group P4/nmm
and lattice parameters a=4.0367(1) {\AA} and c=8.5262(2) {\AA} at 300 K. The
electrical resistivity and dc magnetic susceptibility measurements indicate
superconductivity at 30 K for the nominally undoped ThFeAsN.


title: Multidimensional L\'evy White Noises in Weighted Besov Spaces

abstract:
  In this paper, we study the Besov regularity of d-dimensional L\'evy white
noises. More precisely, we describe new sample paths properties of a given
white noise in terms of weighted Besov spaces. In particular, the smoothness
and integrability properties of L\'evy white noises are characterized using the
Blumenthal-Getoor indices. Our techniques rely on wavelet methods and
generalized moments estimates for L\'evy white noises.


title: A nested polyhedra model of turbulence

abstract:
  A discretization of the wave-number space is proposed, using nested
polyhedra, in the form of alternating dodecahedra and icosahedra that are
self-similarly scaled. This particular choice allows the possibility of forming
triangles using only discretized wave-vectors when the scaling between two
consecutive dodecahedra is equal to the golden ratio, and the icosahedron
between the two dodecahedra is the dual of the inner dodecahedron.
Alternatively, the same discretization can be described as a logarithmically
spaced (with a scaling equal to the golden ratio), nested
dodecahedron-icosahedron compounds. A wave-vector which points from the origin
to a vertex of such a mesh, can always find two other discretized wave-vectors
that are also on the vertices of the mesh (which is not true for an arbitrary
mesh). Thus, the nested polyhedra grid can be thought of as a reduction (or
decimation) of the Fourier space using a particular set of self-similar triads
aranged approximately in a spherical form. For each vertex (i.e. discretized
wave-vector) in this space, there are either 9 or 15 pairs of vertices (i.e.
wave-vectors) with which the initial vertex can interact to form a triangle.
This allows the reduction of the convolution integral in the Navier-Stokes
equation to a sum over 9 or 15 interaction pairs. Transforming the equation in
Fourier space, to a network of interacting nodes, that can be constructed as a
numerical model, which evolves each component of the velocity vector on each
node of the network. Such a model gives the usual Kolmogorov spectrum. Since
the scaling is logarithmic, and the number of nodes for each scale is constant,
a very large inertial range can be considered with a much lower number of
degrees of freedom. Incidentally, by assuming isotropy and a certain relation
between the phases, the model can be used to systematically derive three
dimensional shell models.


title:
Rungs 1 to 4 of DFT Jacob's ladder: extensive test on the lattice
  constant, bulk modulus, and cohesive energy of solids

abstract:
  A large panel of old and recently proposed exchange-correlation functionals
belonging to rungs 1 to 4 of Jacob's ladder of density functional theory are
tested (with and without a dispersion correction term) for the calculation of
the lattice constant, bulk modulus, and cohesive energy of solids. Particular
attention will be paid to the functionals MGGA_MS2 [J. Sun et al., J. Chem.
Phys. 138, 044113 (2013)], mBEEF [J. Wellendorff et al., J. Chem. Phys. 140,
144107 (2014)], and SCAN [J. Sun et al., Phys. Rev. Lett. 115, 036402 (2015)]
that are approximations of the meta-generalized gradient type and were
developed with the goal to be universally good. Another goal is also to
determine for which semilocal functionals and groups of solids it is beneficial
(or not necessary) to use the Hartree-Fock exchange or a dispersion correction
term.


title:
Discovery of spin-up in the X-ray pulsar companion of the hot subdwarf
  HD 49798

abstract:
  The hot subdwarf HD 49798 has an X-ray emitting compact companion with a
spin-period of 13.2 s and a dynamically measured mass of 1.28+/-0.05 M_sun,
consistent with either a neutron star or a white dwarf. Using all the available
XMM-Newton and Swift observations of this source, we could perform a
phase-connected timing analysis extending back to the ROSAT data obtained in
1992. We found that the pulsar is spinning up at a rate of
(2.15+/-0.05)x10^{-15} s/s. This result is best interpreted in terms of a
neutron star accreting from the wind of its subdwarf companion, although the
remarkably steady period derivative over more than 20 years is unusual in
wind-accreting neutron stars. The possibility that the compact object is a
massive white dwarf accreting through a disk cannot be excluded, but it
requires a larger distance and/or properties of the stellar wind of HD 49798
different from those derived from the modelling of its optical/UV spectra.


title:
Ion cyclotron resonance heating systems upgrade toward high power and CW
  operations in WEST

abstract:
  The design of the WEST (Tungsten-W Environment in Steady-state Tokamak) Ion
cyclotron resonance heating antennas is based on a previously tested
conjugate-T Resonant Double Loops prototype equipped with internal vacuum
matching capacitors. The design and construction of three new WEST ICRH
antennas are being carried out in close collaboration with ASIPP, within the
framework of the Associated Laboratory in the fusion field between IRFM and
ASIPP. The coupling performance to the plasma and the load-tolerance have been
improved, while adding Continuous Wave operation capability by introducing
water cooling in the entire antenna. On the generator side, the operation class
of the high power tetrodes is changed from AB to B in order to allow high power
operation (up to 3 MW per antenna) under higher VSWR (up to 2:1). Reliability
of the generators is also improved by increasing the cavity breakdown voltage.
The control and data acquisition system is also upgraded in order to resolve
and react on fast events, such as ELMs. A new optical arc detection system
comes in reinforcement of the V r /V f and SHAD systems.


title: A Novel Sufficient Condition for Generalized Orthogonal Matching Pursuit

abstract:
  Generalized orthogonal matching pursuit (gOMP), also called orthogonal
multi-matching pursuit, is an extension of OMP in the sense that $N\geq1$
indices are identified per iteration. In this paper, we show that if the
restricted isometry constant (RIC) $\delta_{NK+1}$ of a sensing matrix $\A$
satisfies $\delta_{NK+1} < 1/\sqrt {K/N+1}$, then under a condition on the
signal-to-noise ratio, gOMP identifies at least one index in the support of any
$K$-sparse signal $\x$ from $\y=\A\x+\v$ at each iteration, where $\v$ is a
noise vector. Surprisingly, this condition does not require $N\leq K$ which is
needed in Wang, \textit{et al} 2012 and Liu, \textit{et al} 2012. Thus, $N$ can
have more choices. When $N=1$, it reduces to be a sufficient condition for OMP,
which is less restrictive than that proposed in Wang 2015. Moreover, in the
noise-free case, it is a sufficient condition for accurately recovering $\x$ in
$K$ iterations which is less restrictive than the best known one. In
particular, it reduces to the sharp condition proposed in Mo 2015 when $N=1$.


title: Inferential Privacy Guarantees for Differentially Private Mechanisms

abstract:
  The correlations and network structure amongst individuals in datasets
today---whether explicitly articulated, or deduced from biological or
behavioral connections---pose new issues around privacy guarantees, because of
inferences that can be made about one individual from another's data. This
motivates quantifying privacy in networked contexts in terms of "inferential
privacy"---which measures the change in beliefs about an individual's data from
the result of a computation---as originally proposed by Dalenius in the 1970's.
Inferential privacy is implied by differential privacy when data are
independent, but can be much worse when data are correlated; indeed, simple
examples, as well as a general impossibility theorem of Dwork and Naor,
preclude the possibility of achieving non-trivial inferential privacy when the
adversary can have arbitrary auxiliary information. In this paper, we ask how
differential privacy guarantees translate to guarantees on inferential privacy
in networked contexts: specifically, under what limitations on the adversary's
information about correlations, modeled as a prior distribution over datasets,
can we deduce an inferential guarantee from a differential one?
  We prove two main results. The first result pertains to distributions that
satisfy a natural positive-affiliation condition, and gives an upper bound on
the inferential privacy guarantee for any differentially private mechanism.
This upper bound is matched by a simple mechanism that adds Laplace noise to
the sum of the data. The second result pertains to distributions that have weak
correlations, defined in terms of a suitable "influence matrix". The result
provides an upper bound for inferential privacy in terms of the differential
privacy parameter and the spectral norm of this matrix.


title: Modelling, controlling, predicting blackouts

abstract:
  The electric power system is one of the cornerstones of modern society. One
of its most serious malfunctions is the blackout, a catastrophic event that may
disrupt a substantial portion of the system, playing havoc to human life and
causing great economic losses. Thus, understanding the mechanisms leading to
blackouts and creating a reliable and resilient power grid has been a major
issue, attracting the attention of scientists, engineers and stakeholders. In
this paper, we study the blackout problem in power grids by considering a
practical phase-oscillator model. This model allows one to simultaneously
consider different types of power sources (e.g., traditional AC power plants
and renewable power sources connected by DC/AC inverters) and different types
of loads (e.g., consumers connected to distribution networks and consumers
directly connected to power plants). We propose two new control strategies
based on our model, one for traditional power grids, and another one for smart
grids. The control strategies show the efficient function of the fast-response
energy storage systems in preventing and predicting blackouts in smart grids.
This work provides innovative ideas which help us to build up a robuster and
more economic smart power system.


title:
Electron-boson spectral density function of correlated multiband systems
  obtained from optical data: Ba0.6K0.4Fe2As2 and LiFeAs

abstract:
  We introduce an approximate method which can be used to simulate the optical
conductivity data of correlated multiband systems for normal and
superconducting cases by taking advantage of a reverse process of a usual
optical data analysis, which has been used to extract the electron-boson
spectral density function from measured optical spectra of single-band systems,
like cuprates. We applied this method to optical conductivity data of two
multiband pnictide systems (Ba0.6K0.4Fe2As2 and LiFeAs) and obtained the
electron-boson spectral density functions. The obtained electron-boson spectral
density consists of a sharp mode and a broad background. The obtained spectral
density functions of the multiband systems show similar properties as those of
cuprates in several aspects. We expect that our method helps to reveal the
nature of strong correlations in the multiband pnictide superconductors.


title: Hoaxy: A Platform for Tracking Online Misinformation

abstract:
  Massive amounts of misinformation have been observed to spread in
uncontrolled fashion across social media. Examples include rumors, hoaxes, fake
news, and conspiracy theories. At the same time, several journalistic
organizations devote significant efforts to high-quality fact checking of
online claims. The resulting information cascades contain instances of both
accurate and inaccurate information, unfold over multiple time scales, and
often reach audiences of considerable size. All these factors pose challenges
for the study of the social dynamics of online news sharing. Here we introduce
Hoaxy, a platform for the collection, detection, and analysis of online
misinformation and its related fact-checking efforts. We discuss the design of
the platform and present a preliminary analysis of a sample of public tweets
containing both fake news and fact checking. We find that, in the aggregate,
the sharing of fact-checking content typically lags that of misinformation by
10--20 hours. Moreover, fake news are dominated by very active users, while
fact checking is a more grass-roots activity. With the increasing risks
connected to massive online misinformation, social news observatories have the
potential to help researchers, journalists, and the general public understand
the dynamics of real and fake news sharing.


title: Rapidly Mixing Markov Chains: A Comparison of Techniques (A Survey)

abstract:
  We survey existing techniques to bound the mixing time of Markov chains. The
mixing time is related to a geometric parameter called conductance which is a
measure of edge-expansion. Bounds on conductance are typically obtained by a
technique called "canonical paths" where the idea is to find a set of paths,
one between every source-destination pair, such that no edge is heavily
congested. However, the canonical paths approach cannot always show rapid
mixing of a rapidly mixing chain. This drawback disappears if we allow the flow
between a pair of states to be spread along multiple paths. We prove that for a
large class of Markov chains canonical paths does capture rapid mixing.
Allowing multiple paths to route the flow still does help a great deal in
proofs, as illustrated by a result of Morris & Sinclair (FOCS'99) on the rapid
mixing of a Markov chain for sampling 0/1 knapsack solutions.
  A different approach to prove rapid mixing is "Coupling". Path Coupling is a
variant discovered by Bubley & Dyer (FOCS'97) that often tremendously reduces
the complexity of designing good Couplings. We present several applications of
Path Coupling in proofs of rapid mixing. These invariably lead to much better
bounds on mixing time than known using conductance, and moreover Coupling based
proofs are typically simpler. This motivates the question of whether Coupling
can be made to work whenever the chain is rapidly mixing. This question was
answered in the negative by Kumar & Ramesh (FOCS'99), who showed that no
Coupling strategy can prove the rapid mixing of the Jerrum-Sinclair chain for
sampling perfect and near-perfect matchings.


title:
Quadrupolar Effects on Nuclear Spins of Neutral Arsenic Donors in
  Silicon

abstract:
  We present electrically detected electron nuclear double resonance
measurements of the nuclear spins of ionized and neutral arsenic donors in
strained silicon. In addition to a reduction of the hyperfine coupling, we find
significant quadrupole interactions of the nuclear spin of the neutral donors
of the order of 10 kHz. By comparing these to the quadrupole shifts due to
crystal fields measured for the ionized donors, we identify the effect of the
additional electron on the electric field gradient at the nucleus. This extra
component is expected to be caused by the coupling to electric field gradients
created due to changes in the electron wavefunction under strain.


title: A Bayesian Model of Multilingual Unsupervised Semantic Role Induction

abstract:
  We propose a Bayesian model of unsupervised semantic role induction in
multiple languages, and use it to explore the usefulness of parallel corpora
for this task. Our joint Bayesian model consists of individual models for each
language plus additional latent variables that capture alignments between roles
across languages. Because it is a generative Bayesian model, we can do
evaluations in a variety of scenarios just by varying the inference procedure,
without changing the model, thereby comparing the scenarios directly. We
compare using only monolingual data, using a parallel corpus, using a parallel
corpus with annotations in the other language, and using small amounts of
annotation in the target language. We find that the biggest impact of adding a
parallel corpus to training is actually the increase in mono-lingual data, with
the alignments to another language resulting in small improvements, even with
labeled data for the other language.


title: Perturbative loop corrections and nonlocal gravity

abstract:
  Nonlocal gravity has been shown to provide a phenomenologically viable
infrared modification of GR. A natural question is whether the required
nonlocality can emerge from perturbative quantum loop corrections due to light
particles. We show that this is not the case. For the value of the mass scale
of the non-local models required by cosmology, the perturbative form factors
obtained from the loop corrections, in the present cosmological epoch, are in
the regime where they are local. The mechanism behind the generation of the
required nonlocality must be more complex, possibly related to strong infrared
effects and non-perturbative mass generation for the conformal mode.


title:
Two-color coherent control of femtosecond above-threshold photoemission
  from a tungsten nanotip

abstract:
  We demonstrate coherent control of multiphoton and above-threshold
photoemission from a single solid-state nanoemitter driven by a fundamental and
a weak second harmonic laser pulse. Depending on the relative phase of the two
pulses, electron emission is modulated with a contrast of the oscillating
current signal of up to 94%. Electron spectra reveal that all observed photon
orders are affected simultaneously and similarly. We confirm that photoemission
takes place within 10 fs. Accompanying simulations indicate that the current
modulation with its large contrast results from two interfering quantum
pathways leading to electron emission.


title:
Optimal Control of a Parabolic Distributed Parameter System Using a
  Barycentric Shifted Gegenbauer Pseudospectral Method

abstract:
  In this paper, we introduce a novel pseudospectral method for the numerical
solution of optimal control problems governed by a parabolic distributed
parameter system. The infinite-dimensional optimal control problem is reduced
into a finite-dimensional nonlinear programming problem through shifted
Gegenbauer quadratures constructed using a stable barycentric representation of
Lagrange interpolating polynomials and explicit barycentric weights for the
shifted Gegenbauer-Gauss (SGG) points. A rigorous error analysis of the method
is presented, and a numerical test example is given to show the accuracy and
efficiency of the proposed pseudospectral method.


title:
Rotating effects on the Landau quantization for an atom with a magnetic
  quadrupole moment

abstract:
  Based on the single particle approximation [V. F. Dmitriev {\it et al}, Phys.
Rev. C {\bf50}, 2358 (1994), C.-C. Chen, Phys. Rev. A {\bf51}, 2611 (1995)],
the Landau quantization associated with an atom with a magnetic quadrupole
moment is introduced, and then, rotating effects on this analogue of the Landau
quantization is investigated. It is shown that rotating effects can modify the
cyclotron frequency and breaks the degeneracy of the analogue of the Landau
levels.


title:
Regularity and growth conditions for fast escaping points of entire
  functions

abstract:
  Let $f$ be a transcendental entire function. The quite fast escaping set,
$Q(f)$, and the set $Q_2(f),$ which was defined recently, are equal to the fast
escaping set, $A(f),$ under certain conditions. In this paper we generalise
these sets by introducing a family of sets $Q_m(f)$, $m \in \mathbb{N}.$ We
also give one regularity and one growth condition which imply that $Q_m(f)$ is
equal to $A(f)$ and we show that all functions of finite order and positive
lower order satisfy $Q_m(f)=A(f)$ for any $m$. Finally, we relate the new
regularity condition to a sufficient condition for $Q_2(f)=A(f)$ introduced in
recent work.


title: Optimized Polynomial Evaluation with Semantic Annotations

abstract:
  In this paper we discuss how semantic annotations can be used to introduce
mathematical algorithmic information of the underlying imperative code to
enable compilers to produce code transformations that will enable better
performance. By using this approaches not only good performance is achieved,
but also better programmability, maintainability and portability across
different hardware architectures. To exemplify this we will use polynomial
equations of different degrees.


title:
Characterization of Dimethylsulfoxide / Glycerol Mixtures: A Binary
  Solvent System for the Study of "Friction-Dependent" Chemical Reactivity

abstract:
  The properties of binary mixtures of dimethylsulfoxide and glycerol, measured
by several techniques, are reported. Special attention is given to those
properties contributing or affecting chemical reactions. In this respect the
investigated mixture behaves as a relatively simple solvent and it is
especially well suited for studies on the influence of viscosity in chemical
reactivity. This is due to the relative invariance of the dielectric properties
of the mixture. However, special caution must be taken with specific solvation,
as the hydrogen-bonding properties of the solvent changes with the molar
fraction of glycerol.


title:
Improved analyses for $\mu^-e^-\rightarrow e^-e^-$ in muonic atoms by
  contact interactions

abstract:
  The charged lepton flavor violating (CLFV) processes of $\mu^-e^-\rightarrow
e^-e^-$ decay by four Fermi contact interactions in a muonic atom for various
atoms are investigated. The wave functions of bound and scattering state
leptons are properly treated by solving Dirac equations with Coulomb
interaction of the finite nuclear charge distributions. This new effect
contributes significantly in particular for heavier atoms, where the obtained
decay rate is about one order of magnitude larger than the previous estimation
for $^{208}$Pb. We find that, as the atomic number $Z$ increases, the
$\mu^-e^-\rightarrow e^-e^-$ decay rates increase more rapidly than the result
of the previous work of $Z^3$, suggesting this decay as one of the promising
processes to search for CLFV interaction.


title: Collecting Examples for Instance-Spanning Constraints

abstract:
  This report presents a meta analysis of various sources from literature,
research projects, and experience with the goal of collecting examples for
instance-spanning constraints to be implemented through Process-Aware
Information Systems.


title:
Analyzing Games with Ambiguous Player Types using the ${\rm MINthenMAX}$
  Decision Model

abstract:
  In many common interactive scenarios, participants lack information about
other participants, and specifically about the preferences of other
participants. In this work, we model an extreme case of incomplete information,
which we term games with type ambiguity, where a participant lacks even
information enabling him to form a belief on the preferences of others. Under
type ambiguity, one cannot analyze the scenario using the commonly used
Bayesian framework, and therefore he needs to model the participants using a
different decision model.
  In this work, we present the ${\rm MINthenMAX}$ decision model under
ambiguity. This model is a refinement of Wald's MiniMax principle, which we
show to be too coarse for games with type ambiguity. We characterize ${\rm
MINthenMAX}$ as the finest refinement of the MiniMax principle that satisfies
three properties we claim are necessary for games with type ambiguity. This
prior-less approach we present her also follows the common practice in computer
science of worst-case analysis.
  Finally, we define and analyze the corresponding equilibrium concept assuming
all players follow ${\rm MINthenMAX}$. We demonstrate this equilibrium by
applying it to two common economic scenarios: coordination games and bilateral
trade. We show that in both scenarios, an equilibrium in pure strategies always
exists and we analyze the equilibria.


title:
The structure of low-lying states in ${}^{140}$Sm studied by Coulomb
  excitation

abstract:
  The electromagnetic structure of $^{140}$Sm was studied in a low-energy
Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE
facility at CERN. The $2^+$ and $4^+$ states of the ground-state band and a
second $2^+$ state were populated by multi-step excitation. The analysis of the
differential Coulomb excitation cross sections yielded reduced transition
probabilities between all observed states and the spectroscopic quadrupole
moment for the $2_1^+$ state. The experimental results are compared to
large-scale shell model calculations and beyond-mean-field calculations based
on the Gogny D1S interaction with a five-dimensional collective Hamiltonian
formalism. Simpler geometric and algebraic models are also employed to
interpret the experimental data. The results indicate that $^{140}$Sm shows
considerable $\gamma$ softness, but in contrast to earlier speculation no signs
of shape coexistence at low excitation energy. This work sheds more light on
the onset of deformation and collectivity in this mass region.


title:
Dynamical conductivity and its fluctuations along the crossover to
  many-body localization

abstract:
  We present a numerical study of the many-body localization (MBL) phenomenon
in the high-temperature limit within an anisotropic Heisenberg model with
random local fields. Taking the dynamical spin conductivity $\sigma(\omega)$ as
the test quantity, we investigate the full frequency dependence of
sample-to-sample fluctuations and their scaling properties as a function of the
system size $L\leq 28$ and the frequency resolution. We identify differences
between the general interacting case $\Delta>0$ and the anisotropy $\Delta=0$,
the latter corresponding to the standard Anderson localization. Except for the
extreme MBL case when the relative sample-to-sample fluctuations became large,
numerical results allow for the extraction of the low-$\omega$ dependence of
the conductivity. Results for the d.c. value $\sigma_0$ indicate a crossover
into the MBL regime, i.e. an exponential-like variation with the disorder
strength $W$. For the same regime, our numerical analysis indicates that the
low-frequency exponent $\alpha$ exhibits a small departure from $\alpha\sim 1$
only.


title: Random Locations of Periodic Stationary Processes

abstract:
  We consider a family of random locations, called intrinsic location
functionals, of periodic stationary processes. This family includes but is not
limited to the location of the path supremum and first/last hitting times. We
first show that the set of all possible distributions of intrinsic location
functionals for periodic stationary processes is the convex hull generated by a
specific group of distributions. We then focus on two special subclasses of
these random locations. For the first subclass, the density has a uniform lower
bound; for the second subclass, the possible distributions are closely related
to the concept of joint mixability.


title: Quantum Larmor radiation in de Sitter spacetime

abstract:
  We study the radiation emitted by inertial charge evolving on the expanding
de Sitter spacetime. Performing a perturbative calculation, within scalar
quantum electrodynamics (sQED), we obtain the transition amplitude for the
process and using this we define the energy radiated by the source. In the
non-relativistic limit we find that the leading term is compatible with the
classical result (Larmor formula). The first quantum correction is found to be
negative, a result which is in line with a number of similar quantum field
theory results. For the ultra-relativistic case we find a logarithmic
divergence of the emitted energy for large frequencies, which we link to the
nature of the spacetime. We compare our results with that of Nomura et al.
(2006), where the authors make a similar calculation for a general conformally
flat spacetime.


title: Delta State Replicated Data Types

abstract:
  CRDTs are distributed data types that make eventual consistency of a
distributed object possible and non ad-hoc. Specifically, state-based CRDTs
ensure convergence through disseminating the entire state, that may be large,
and merging it to other replicas; whereas operation-based CRDTs disseminate
operations (i.e., small states) assuming an exactly-once reliable dissemination
layer. We introduce Delta State Conflict-Free Replicated Data Types
($\delta$-CRDTs) that can achieve the best of both worlds: small messages with
an incremental nature, as in operation-based CRDTs, disseminated over
unreliable communication channels, as in traditional state-based CRDTs. This is
achieved by defining delta mutators to return a delta-state, typically with a
much smaller size than the full state, that to be joined with both local and
remote states. We introduce the $\delta$-CRDT framework, and we explain it
through establishing a correspondence to current state-based CRDTs. In
addition, we present an anti-entropy algorithm for eventual convergence, and
another one that ensures causal consistency. Finally, we introduce several
$\delta$-CRDT specifications of both well-known replicated datatypes and novel
datatypes, including a generic map composition.


title: Non-Markovianity of geometrical qudit decoherence

abstract:
  In the following paper, we generalize the geometrical framework of qubit
decoherence to higher dimensions. The quantum mixed state is represented by the
probability distribution, which is the K\"ahler function on the projective
Hilbert space. The Markovian master equation for density operators turns out to
be equivalent to the Fokker-Planck equation for quantum probability
distributions. Several examples are analyzed, featuring different
generalizations of the Pauli channel.


title:
Estimation of physical conditions in the cold phase of the ISM in the
  sub-DLA system at z = 2.06 in the spectrum of the quasar J2123-0050

abstract:
  An independent analysis of the molecular hydrogen absorption system at z =
2.059 in the spectrum of the quasar J2123-0050 is presented. The H_2 system
consists of two components (A and B) with column densities log N^A(H_2) =
17.94+/-0.01 and log N^B(H_2) = 15.16+/-0.02. The spectrum exhibits the lines
of HD molecules (log N^A(HD) = 13.87+/-0.06) and the neutral species C I and Cl
I associated with the H_2 absorption system. For the molecular hydrogen lines
near the quasar's Ly_beta and O VI emission lines, we detect a nonzero residual
flux, ~3% of the total flux, caused by the effect of partial coverage of the
quasar's broad-line region by an H_2 cloud. The uniqueness of the system being
investigated is manifested in a high abundance of the neutral species H_2 and C
I at the lowest H I column density, log N(H I) = 19.18+/-0.15, among the high
redshift systems. The N(HD)/2N(H_2) ratio for component A has turned out to be
also unusually high, (4.26+/-0.60)x10^{-5}. We have investigated the physical
conditions in components A and B. Component A represents the optically thick
case; the gas has a low number density (n~30 cm^{-3}) and a temperature T~140
K. In component B, the medium is optically thin with n<100 cm^{-3} and T<100 K.
The ultraviolet (UV) background intensity in the clouds exceeds the mean
intensity in our Galaxy by almost an order of magnitude. A high gas ionization
fraction, n(H+)/n(H)~10^{-2}, which can be the result of partial shielding of
the system from hard UV radiation, is needed to describe the high HD and C I
column densities. Using our simulations with the PDR Meudon code, we can
reconstruct the observed column densities of the species within the model with
a constant density n(H)=40 cm^{-3}. A high H_2 formation rate (higher than the
mean Galactic value by a factor of 10-40) and high gas ionization fraction and
UV background intensity are needed in this case.


title: Support points and the Bieberbach conjecture in higher dimension

abstract:
  We describe some open questions related to support points in the class $S^0$
and introduce some useful techniques toward a higher dimensional Bieberbach
conjecture.


title:
AC Power Flow Data in MATPOWER and QCQP Format: iTesla, RTE Snapshots,
  and PEGASE

abstract:
  In this paper, we publish nine new test cases in MATPOWER format. Four test
cases are French very high-voltage grid generated by the offline plateform of
iTesla: part of the data was sampled. Four test cases are RTE snapshots of the
full French very high-voltage and high-voltage grid that come from French
SCADAs via the Convergence software. The ninth and largest test case is a
pan-European ficticious data set that stems from the PEGASE project. It
complements the four PEGASE test cases that we previously published in MATPOWER
version 5.1 in March 2015. We also provide a MATLAB code to transform the data
into standard mathematical optimization format. Computational results
confirming the validity of the data are presented in this paper.


title:
Broadband Observations of the Gamma-ray Emitting Narrow Line Seyfert 1
  Galaxy SBS 0846+513

abstract:
  We present the results of our broadband study of the $\gamma$-ray emitting
narrow line Seyfert 1 (NLSy1) galaxy SBS 0846+513 ($z=0.585$). This includes
multi-band flux variations, $\gamma$-ray spectral analysis, broad band spectral
energy distribution (SED) modeling, and intranight optical variability (INOV)
observations carried over 6 nights between 2012 November and 2013 March using
the 2 m Himalayan Chandra Telescope and the 1.3 m telescope at Devasthal.
Multiple episodes of flaring activity are seen in the $\gamma$-ray light curve
of the source which are also reflected in the observations at lower
frequencies. A statistically significant curvature is noticed in the seven
years averaged $\gamma$-ray spectrum, thus indicating its similarity with
powerful flat spectrum radio quasars (FSRQs). Modeling the SEDs with a one zone
leptonic emission model hints the optical-UV spectrum to be dominated by
synchrotron radiation, whereas, inverse Compton scattering of broad line region
photons reproduces the $\gamma$-ray part of the SEDs. The source was found to
be variable on all the six nights of optical observations with a variation of
$\sim$0.3 magnitude within a single night, coinciding with a high $\gamma$-ray
activity state. The observed large amplitude INOV clearly indicates the
presence of a closely aligned beamed relativistic jet in SBS 0846+513. Our
broadband study supports the recent claims in literature that $\gamma$-ray
emitting NLSy1 galaxies are similar to blazars and constitute the low black
hole mass counterparts to FSRQs.


title:
Geometry of the closed unit ball of the space of bilinear forms on
  $\ell_{\infty}^{2}$

abstract:
  We obtain all extreme and exposed points of the closed unit ball of the space
of bilinear forms $T:\ell_{\infty}^{2}\times\ell_{\infty}^{2}\rightarrow
\mathbb{R}.$ We also show that any (norm one) bilinear form $T:\ell_{\infty
}^{2}\times\ell_{\infty}^{2}\rightarrow\mathbb{R}$ for which the optimal
constant of the Littlewood's $4/3$ inequality is achieved is necessarily an
extreme point. In the case of complex scalars we combine analytical and
numerical evidences supporting that, at least for complex bilinear forms with
real coefficients, the optimal constant of Littlewood's $4/3$ inequality seems
to the the trivial, i.e., $1.$


title:
Effective use of the PGAS Paradigm: Driving Transformations and
  Self-Adaptive Behavior in DASH-Applications

abstract:
  DASH is a library of distributed data structures and algorithms designed for
running the applications on modern HPC architectures, composed of hierarchical
network interconnections and stratified memory. DASH implements a PGAS
(partitioned global address space) model in the form of C++ templates, built on
top of DART -- a run-time system with an abstracted tier above existing
one-sided communication libraries.
  In order to facilitate the application development process for exploiting the
hierarchical organization of HPC machines, DART allows to reorder the placement
of the computational units. In this paper we present an automatic, hierarchical
units mapping technique (using a similar approach to the Hilbert curve
transformation) to reorder the placement of DART units on the Cray XC40 machine
Hazel Hen at HLRS. To evaluate the performance of new units mapping which takes
into the account the topology of allocated compute nodes, we perform latency
benchmark for a 3D stencil code. The technique of units mapping is generic and
can be be adopted in other DART communication substrates and on other hardware
platforms.
  Furthermore, high--level features of DASH are presented, enabling more
complex automatic transformations and optimizations in the future.


title: $n$-transitivity of bisection groups of a Lie groupoid

abstract:
  The notion of $n$-transitivity can be carried over from groups of
diffeomorphisms on a manifold $M$ to groups of bisections of a Lie groupoid
over $M$. The main theorem states that the $n$-transitivity is fulfilled for
all $n\in\mathbb N$ by an arbitrary group of $C^r$-bisections of a Lie groupoid
$\Gamma$ of class $C^r$, where $1\leq r\leq\omega$, under mild conditions. For
instance, the group of all bisections of any Lie groupoid and the group of all
Lagrangian bisections of any symplectic groupoid are $n$-transitive in the
sense of this theorem. In particular, if $\Gamma$ is source connected for any
arrow $\gamma\in\Gamma$ there is a bisection passing through $\gamma$.


title: Towering phenomena for the Yamabe equation on symmetric manifolds

abstract:
  Let $(M,g)$ be a compact smooth connected Riemannian manifold (without
boundary) of dimension $N\ge7$. Assume $M$ is symmetric with respect to a point
$\xi_0$ with non-vanishing Weyl's tensor. We consider the linear perturbation
of the Yamabe problem $$(P_\epsilon)\qquad-\mathcal L_g u+\epsilon
u=u^{N+2\over N-2}\ \hbox{in}\ (M,g) .$$ We prove that for any $k\in \mathbb
N$, there exists $\epsilon_k>0$ such that for all $\epsilon\in (0, \epsilon_k)$
the problem $(P_\epsilon)$ has a symmetric solution $u_\epsilon ,$ which looks
like the superposition of $k$ positive bubbles centered at the point $\xi_0$ as
$\epsilon\to 0$. In particular, $\xi_0$ is a {\em towering} blow-up point.


title:
Horizon, homogeneity and flatness problems -- do their resolutions
  really depend upon inflation?

abstract:
  We point out that the horizon problem encountered in standard text-books or
review papers on cosmology is, in general, derived for world models based on
Robertson-Walker line element where homogeneity and isotropy of the universe --
\`a la cosmological principle -- is assumed to begin with and is guaranteed for
all epochs. Actually what all happens in that scenario is that in such a
universe, whose evolutionary behaviour is described by a single scale factor,
which may be time dependent but is otherwise independent of spatial
coordinates, the light signals in a finite time might not be covering all the
available space. Further, the flatness problem, as it is posed, is not even
falsifiable. The usual argument offered in the literature is that the present
density of the universe is very close to the critical density value and that
the universe must be flat since otherwise in past at $\sim10^{-35}$ second
(near the epoch of inflation) there will be extremely low departures of density
from the critical density value (of the order $\sim10^{-53}$), requiring a sort
of fine tuning. We show that even if the present value of the density parameter
were very different, still at $10^{-35}$ second it would differ from unity by
the same fraction. Thus a use of fine tuning argument to promote $k = 0$ model
amounts to {\em a priori} rejection of all models with $k \ne 0$. Without
casting any aspersions on the inflationary theory, which after all is the most
promising paradigm to explain the pattern of anisotropies observed in the
cosmic microwave background, we argue that one cannot use homogeneity and
flatness in support of inflation.


title: Convexity at finite temperature and non-extensive thermodynamics

abstract:
  Assuming that tunnel effect between two degenerate bare minima occurs, in a
scalar field theory at finite volume, this article studies the consequences for
the effective potential, to all loop orders. Convexity is achieved only if the
two bare minima are taken into account in the path integral, and a new
derivation of the effective potential is given, in the large volume limit. The
effective potential has then has a universal form, it is suppressed by the
space time volume, and does not feature spontaneous symmetry breaking as long
as the volume is finite. The finite temperature analysis leads to surprising
thermal properties, following from the non-extensive expression for the free
energy. Although the physical relevance of these results is not clear, the
potential application to ultra-light scalar particles is discussed.


title: Parallel Texts in the Hebrew Bible, New Methods and Visualizations

abstract:
  In this article we develop an algorithm to detect parallel texts in the
Masoretic Text of the Hebrew Bible. The results are presented online and
chapters in the Hebrew Bible containing parallel passages can be inspected
synoptically. Differences between parallel passages are highlighted. In a
similar way the MT of Isaiah is presented synoptically with 1QIsaa. We also
investigate how one can investigate the degree of similarity between parallel
passages with the help of a case study of 2 Kings 19-25 and its parallels in
Isaiah, Jeremiah and 2 Chronicles.


title:
Centralized group key management scheme for secure multicast
  communication without re-keying

abstract:
  In the secure group communication, data is transmitted in such a way that
only the group members are able to receive the messages. The main problem in
the solution using symmetric key is heavy re-keying cost. To reduce re-keying
cost tree based architecture is used. But it requires extra overhead to balance
the key- tree in order to achieve logarithmic re-keying cost. The main
challenging issue in dynamic and secure multimedia multicast communication is
to design a centralized group key management scheme with minimal computational,
communicational and storages complexities without breaching security issues.
Several authors have proposed different centralized group key management
schemes, wherein one of them proposes reducing communicational complexity but
increases computational and storage costs however another proposes decreasing
the computational and storage costs which eventually breaches forward and
backward secrecy. In this paper we propose a comparatively more efficient
centralized group key management scheme that not only minimize the
computational, communicational and storages complexities but also maintaining
the security at the optimal level. The message encryptions and decryptions
costs are also minimized. Further, we also provide an extended multicast
scheme, in which the several requests towards leaving or joining the group can
be done by large number of members simultaneously. In order to obtain better
performance of multicast encryption, the symmetric-key and asymmetric-key
cryptosystems may be combined.


title:
The First GeV Outburst of the Radio-loud Narrow Line Seyfert 1 galaxy
  PKS 1502+036

abstract:
  The $\gamma$-ray loud narrow line Seyfert 1 ($\gamma$-NLSy1) galaxy PKS
1502+036 ($z=0.409$) exhibited its first $\gamma$-ray outburst on 2015 December
20. In the energy range of 0.1-300 GeV, the highest flux measured by {\it
Fermi}-Large Area Telescope is (3.90 $\pm$ 1.52) $\times$ 10$^{-6}$ ph
cm$^{-2}$ s$^{-1}$, which is the highest $\gamma$-ray flux ever detected from
this object. The associated spectral shape is soft ($\Gamma_{0.1-300~{\rm
GeV}}=2.57\pm0.17$) and this corresponds to an isotropic $\gamma$-ray
luminosity of (1.2 $\pm$ 0.6) $\times$ 10$^{48}$ erg s$^{-1}$. We generate the
broadband spectral energy distribution (SED) during the GeV flare and reproduce
it using a one zone leptonic emission model. The optical-UV spectrum can be
explained by a combination of synchrotron and the accretion disk emission,
whereas, the X-ray to $\gamma$-ray SED can be satisfactorily reproduced by
inverse-Compton scattering of thermal photons originated from the torus. The
derived SED parameters hint for the increase in the bulk Lorentz factor as a
major cause of the flare and the location of the emission region is estimated
as outside the broad line region but still inside torus. A comparison of the
GeV flaring SED of PKS 1502+036 with that of two other $\gamma$-NLSy1 galaxies,
namely, 1H 0323+342 ($z=0.061$) and PMN J0948+0022 ($z=0.585$), and also with
FSRQ 3C 279 ($z=0.536$) has led to the conclusion that the GeV flaring SEDs of
$\gamma$-NLSy1 galaxies resemble with FSRQs and a major fraction of their
bolometric luminosity is emitted at $\gamma$-ray energies.


title: Development of a low-level Ar-37 calibration standard

abstract:
  Argon-37 is an environmental signature of an underground nuclear explosion.
Producing and quantifying low-level Ar-37 standards is an important step in the
development of sensitive field measurement instruments. This paper describes
progress at Pacific Northwest National Laboratory in developing a process to
generate and quantify low-level Ar-37 standards, which can be used to calibrate
sensitive field systems at activities consistent with soil background levels.
This paper presents a discussion of the measurement analysis, along with
assumptions and uncertainty estimates.


title:
Minimum-Time Transitions between Thermal Equilibrium States of the
  Quantum Parametric Oscillator

abstract:
  In this article, we use geometric optimal control to completely solve the
problem of minimum-time transitions between thermal equilibrium states of the
quantum parametric oscillator, which finds applications in various physical
contexts. We discover a new kind of optimal solutions, absent from all the
previous treatments of the problem.


title: Thermal stability of two-dimensional Topological Color Code

abstract:
  Thermal stability of the Topological Color Code in presence of a thermal bath
is studied. We study the Lindblad evolution of the observables in the weak
coupling limit of the Born-Markov approximation. The auto-correlation functions
of the observables are used as a figure of merit for the thermal stability. We
show that all of the observables auto-correlation functions decay exponentially
in time. By finding a lower bound of the decay rate, which is a constant
independent of the system size, we show that the Topological Color Code is
unstable against thermal fluctuations from the bath at finite temperature, even
though it is stable at T=0 against local quantum perturbations.


title: Text Understanding with the Attention Sum Reader Network

abstract:
  Several large cloze-style context-question-answer datasets have been
introduced recently: the CNN and Daily Mail news data and the Children's Book
Test. Thanks to the size of these datasets, the associated text comprehension
task is well suited for deep-learning techniques that currently seem to
outperform all alternative approaches. We present a new, simple model that uses
attention to directly pick the answer from the context as opposed to computing
the answer using a blended representation of words in the document as is usual
in similar models. This makes the model particularly suitable for
question-answering problems where the answer is a single word from the
document. Ensemble of our models sets new state of the art on all evaluated
datasets.


title: Physical models for the normal YORP and diurnal Yarkovsky effects

abstract:
  We propose an analytic model for the normal YORP and diurnal Yarkovsky
effects experienced by a convex asteroid. Both the YORP torque and the
Yarkovsky force are expressed as integrals of a universal function over the
surface of an asteroid. Although in general this function can only be
calculated numerically from the solution of the heat conductivity equation,
approximate solutions can be obtained in quadratures for important limiting
cases. We consider 3 such simplified models: Rubincam's approximation (zero
heat conductivity), low thermal inertia limit (including the next order
correction and thus valid for small heat conductivity), and high thermal
inertia limit (valid for large heat conductivity). All three simplified models
are compared with the exact solution.


title:
Improved separation of soft and hard components in multiple Coulomb
  scattering

abstract:
  Evaluation of the angular distribution function of particles scattered in an
amorphous medium is improved by deforming the integration path in the Fourier
integral representation into the complex plane. That allows us to present the
distribution function as a sum of two positive components, soft and hard, the
soft component being close to a Gaussian, and the hard component vanishing in
the forward direction, while including the Rutherford asymptotics and all the
power corrections to it at large scattering angles. Detailed properties of
those components, and their interplay at intermediate deflection angles are
discussed. Comparison with the Moli\`{e}re theory is given.


title:
Reconstructing the topology on monoids and polymorphism clones of the
  rationals

abstract:
  We show how to reconstruct the topology on the monoid of endomorphisms of the
rational numbers under the strict or reflexive order relation, and the
polymorphism clone of the rational numbers under the reflexive relation. In
addition we show how automatic homeomorphicity results can be lifted to
polymorphism clones generated by monoids.


title:
Perfect and $\varepsilon$-Perfect Simulation Methods for the One
  Dimensional Kac Equation

abstract:
  We review the derivation of the Kac master equation model for random
collisions of particles, its relationship to the Poisson process, and existing
algorithms for simulating values from the marginal distribution of velocity for
a single particle at any given time. We describe and implement a new algorithm
that efficiently and more fully leverages properties of the Poisson process,
show that it performs at least as well as existing methods, and give empirical
evidence that it may perform better at capturing the tails of the single
particle velocity distribution. Finally, we derive and implement a novel
"$\varepsilon$-perfect sampling" algorithm for the limiting marginal
distribution as time goes to infinity. In this case the importance is a proof
of concept that has the potential to be expanded to more interesting (DSMC)
direct simulation Monte Carlo applications.


title:
A stochastic model of solid state thin film deposition: application to
  chalcopyrite growth

abstract:
  Developing high fidelity quantitative models of solid state reaction systems
can be challenging, especially in deposition systems where, in addition to the
multiple competing processes occurring simultaneously, the solid interacts with
its atmosphere. In this work, we develop a model for the growth of a thin solid
film where species from the atmosphere adsorb, diffuse, and react with the
film. The model is mesoscale and describes an entire film with thickness on the
order of microns. Because it is stochastic, the model allows us to examine
inhomogeneities and agglomerations that would be impossible to characterize
with deterministic methods. We demonstrate the modeling approach with the
example of chalcopyrite Cu(InGa)(SeS)$_2$ thin film growth via precursor
reaction, which is a common industrial method for fabricating thin film
photovoltaic modules. The model is used to understand how and why through-film
variation in the composition of Cu(InGa)(SeS)$_2$ thin films arises and
persists. We believe that the model will be valuable as an effective
quantitative description of many other materials systems used in
semiconductors, energy storage, and other fast-growing industries.


title: On-chip quantum interference of a superconducting microsphere

abstract:
  We propose and analyze an all-magnetic scheme to perform a Young's double
slit experiment with a micron-sized superconducting sphere of mass $\gtrsim
{10}^{13}$ amu. We show that its center of mass could be prepared in a spatial
quantum superposition state with an extent of the order of half a micrometer.
The scheme is based on magnetically levitating the sphere above a
superconducting chip and letting it skate through a static magnetic potential
landscape where it interacts for short intervals with quantum circuits. In this
way, a protocol for fast quantum interferometry using quantum magnetomechanics
is passively implemented. Such a table-top earth-based quantum experiment would
operate in a parameter regime where gravitational energy scales become
relevant. In particular, we show that the faint parameter-free
gravitationally-induced decoherence collapse model, proposed by Di\'osi and
Penrose, could be unambiguously falsified.


title: Variational integrators for interconnected Lagrange-Dirac systems

abstract:
  Interconnected systems are an important class of mathematical models, as they
allow for the construction of complex, hierarchical, multiphysics, and
multiscale models by the interconnection of simpler subsystems. Lagrange--Dirac
mechanical systems provide a broad category of mathematical models that are
closed under interconnection, and in this paper, we develop a framework for the
interconnection of discrete Lagrange--Dirac mechanical systems, with a view
towards constructing geometric structure-preserving discretizations of
interconnected systems. This work builds on previous work on the
interconnection of continuous Lagrange--Dirac systems (Jacobs and Yoshimura
2014) and discrete Dirac variational integrators (Leok and Ohsawa 2011). We
test our results by simulating some of the continuous examples given in Jacobs
and Yoshimura 2014.


title: An approach to categorification of Verma modules

abstract:
  We give a geometric categorification of the Verma modules $M(\lambda)$ for
quantum $\mathfrak{sl}_2$.


title:
Galaxy Luminosity Function of Dynamically Young Abell 119 Cluster:
  Probing the Cluster Assembly

abstract:
  We present the galaxy luminosity function (LF) of the Abell 119 cluster down
to $M_r\sim-14$ mag based on deep images in the $u$-, $g$-, and $r$-bands taken
by using MOSAIC II CCD mounted on the Blanco 4m telescope at the CTIO. The
cluster membership was accurately determined based on the radial velocity
information as well as on the color-magnitude relation for bright galaxies and
the scaling relation for faint galaxies. The overall LF exhibits a bimodal
behavior with a distinct dip at $r\sim18.5$ mag ($M_r\sim-17.8$ mag), which is
more appropriately described by a two-component function. The shape of the LF
strongly depends on the cluster-centric distance and on the local galaxy
density. The LF of galaxies in the outer, low-density region exhibits a steeper
slope and more prominent dip compared with that of counterparts in the inner,
high-density region. We found evidence for a substructure in the projected
galaxy distribution in which several overdense regions in the Abell 119 cluster
appear to be closely associated with the surrounding, possible filamentary
structure. The combined LF of the overdense regions exhibits a two-component
function with a distinct dip, while the LF of the central region is well
described by a single Schechter function. We suggest that, in the context of
the hierarchical cluster formation scenario, the observed overdense regions are
the relics of galaxy groups, retaining their two-component LFs with a dip,
which acquired their shapes through galaxy merging process in group
environments, before they fall into a cluster.


title:
Minimax principles, Hardy-Dirac inequalities and operator cores for two
  and three dimensional Coulomb-Dirac operators

abstract:
  For $n\in\{2,3\}$ we prove minimax characterisations of eigenvalues in the
gap of the $n$ dimensional Dirac operator with an potential, which may have a
Coulomb singularity with a coupling constant up to the critical value
$1/(4-n)$. This result implies a so-called Hardy-Dirac inequality, which can be
used to define a distinguished self-adjoint extension of the Coulomb-Dirac
operator defined on
$\mathsf{C}_{0}^{\infty}(\mathbb{R}^n\setminus\{0\};\mathbb{C}^{2(n-1)})$, as
long as the coupling constant does not exceed $1/(4-n)$. We also find an
explicit description of an operator core of this operator.


title:
Lifshitz-scaling to Lorentz-violating high derivative operator and
  gamma-ray busts

abstract:
  In this work we have used a Ho\v{r}ava-Lifshitz scaling to rewrite a
Lorentz-violating higher-order derivative electrodynamics controlled by a
background four-vector $n_{\mu}$. The photon propagator was obtained and we
have analyzed the dispersion relation and the observational results of
gamma-ray burst (GRB) experiments were used. The limits of the critical
exponent were discussed in the light of the GRB data and the physical
implications were compared with the current GRB-Lorentz-invariance-violation
literature. We show that the bound for the Lorentz-violating coupling for
dimension-six operators, obtained from a Ho\v{r}ava-Lifshitz scaling, is eight
orders of magnitude better than the result found without considering a
Ho\v{r}ava-Lifshitz scaling, also this bound is nearby one, which is expected
to be relevant phenomenologically.


title:
Measuring Type Ia Supernova Populations of Stretch and Color and
  Predicting Distance Biases

abstract:
  Simulations of Type Ia Supernovae (SNIa) surveys are a critical tool for
correcting biases in the analysis of SNIa to infer cosmological parameters.
Large scale Monte Carlo simulations include a thorough treatment of observation
history, measurement noise, intrinsic scatter models and selection effects. In
this paper, we improve simulations with a robust technique to evaluate the
underlying populations of SNIa color and stretch that correlate with
luminosity. In typical analyses, the standardized SNIa brightness is determined
from linear `Tripp' relations between the light curve color and luminosity and
between stretch and luminosity. However, this solution produces Hubble residual
biases because intrinsic scatter and measurement noise result in measured color
and stretch values that do not follow the Tripp relation. We find a $10\sigma$
bias (up to 0.3 mag) in Hubble residuals versus color and $5\sigma$ bias (up to
0.2 mag) in Hubble residuals versus stretch in a joint sample of 920
spectroscopically confirmed SNIa from PS1, SNLS, SDSS and several low-z
surveys. After we determine the underlying color and stretch distributions, we
use simulations to predict and correct the biases in the data. We show that
removing these biases has a small impact on the low-z sample, but reduces the
intrinsic scatter $\sigma_{\textrm{int}}$ from $0.101$ to $0.083$ in the
combined PS1, SNLS and SDSS sample. Past estimates of the underlying
populations were too broad, leading to a small bias in the equation-of-state of
dark energy $w$ of $\Delta w=0.005$.


title: A Survey of Representation Stability Theory

abstract:
  In this survey article we summarize the current state of research in
representation stability theory. We look at three different, yet related,
approaches, using (1) the category of FI-modules, (2) Schur-Weyl duality, and
(3) finitely-generated modules over certain infinite dimensional vector spaces.
The main example is the stability of representations of the symmetric group,
though there have also been some notable generalizations of representation
stability to other groups. This work summarizes the research that both authors
engaged in over the course of the summer of 2015.


title: Volume Entropy

abstract:
  Building on a technical result by Brunnemann and Rideout on the spectrum of
the Volume operator in Loop Quantum Gravity, we show that the dimension of the
space of the quadrivalent, diffeomorphism invariant states with no zero-volume
nodes describing a region with total volume smaller than $V$, has \emph{finite}
dimension, bounded by $V \log V$. This allows us to introduce the notion of
"volume entropy" for this phase space: the von Neumann entropy associated to
the measurement of volume.


title:
A Data-Scalable Randomized Misfit Approach for Solving Large-Scale
  PDE-Constrained Inverse Problems

abstract:
  A randomized misfit approach is presented for the efficient solution of
large-scale PDE-constrained inverse problems with high-dimensional data. The
purpose of this paper is to offer a theory-based framework for random
projections in this inverse problem setting. The stochastic approximation to
the misfit is analyzed using random projection theory. By expanding beyond mean
estimator convergence, a practical characterization of randomized misfit
convergence can be achieved. The theoretical results developed hold with any
valid random projection in the literature. The class of feasible distributions
is broad yet simple to characterize compared to previous stochastic misfit
methods. This class includes very sparse random projections which provide
additional computational benefit. A different proof for a variant of the
Johnson-Lindenstrauss lemma is also provided. This leads to a different
intuition for the $O(\epsilon^{-2})$ factor in bounds for Johnson-Lindenstrauss
results. The main contribution of this paper is a theoretical result showing
the method guarantees a valid solution for small reduced misfit dimensions. The
interplay between Johnson-Lindenstrauss theory and Morozov's discrepancy
principle is shown to be essential to the result. The computational cost
savings for large-scale PDE-constrained problems with high- dimensional data is
discussed. Numerical verification of the developed theory is presented for
model problems of estimating a distributed parameter in an elliptic partial
differential equation. Results with different random projections are presented
to demonstrate the viability and accuracy of the proposed approach.


title:
Scalar-multi-tensorial equivalence for higher order $f\left(
  R,\nabla_{\mu}
  R,\nabla_{\mu_{1}}\nabla_{\mu_{2}}R,...,\nabla_{\mu_{1}}...\nabla_{\mu_{n}
  }R\right)$ theories of gravity

abstract:
  The equivalence between theories depending on the derivatives of $R$, i.e.
$f\left( R,\nabla R,...,\nabla^{n}R\right) $, and scalar-multi-tensorial
theories is verified. The analysis is done in both metric and Palatini
formalisms. It is shown that $f\left( R,\nabla R,...,\nabla^{n}R\right) $
theories are equivalent to scalar-multi-tensorial ones resembling Brans-Dicke
theories with kinetic terms $\omega_{0}=0$ and $\omega_{0}= - \frac{3}{2}$ for
metric and Palatini formalisms respectively. This result is analogous to what
happens for $f(R)$ theories. It is worthy emphasizing that the
scalar-multi-tensorial theories obtained here differ from Brans-Dicke ones due
to the presence of multiple tensorial fields absent in the last. Furthermore,
sufficient conditions are established for $f\left( R,\nabla
R,...,\nabla^{n}R\right) $ theories to be written as scalar-multi-tensorial
theories. Finally, some examples are studied and the comparison of $f\left(
R,\nabla R,...,\nabla^{n}R\right) $ theories to $f\left( R,\Box
R,...\Box^{n}R\right) $ theories is performed.

categories: gr-qc astro-ph.CO hep-th math-ph math.MP


title: High precision grasp pose detection in dense clutter

abstract:
  This paper considers the problem of grasp pose detection in point clouds. We
follow a general algorithmic structure that first generates a large set of
6-DOF grasp candidates and then classifies each of them as a good or a bad
grasp. Our focus in this paper is on improving the second step by using depth
sensor scans from large online datasets to train a convolutional neural
network. We propose two new representations of grasp candidates, and we
quantify the effect of using prior knowledge of two forms: instance or category
knowledge of the object to be grasped, and pretraining the network on simulated
depth data obtained from idealized CAD models. Our analysis shows that a more
informative grasp candidate representation as well as pretraining and prior
knowledge significantly improve grasp detection. We evaluate our approach on a
Baxter Research Robot and demonstrate an average grasp success rate of 93% in
dense clutter. This is a 20% improvement compared to our prior work.


title: Atomic diffusion and mixing in old stars VI: The lithium content of M30

abstract:
  The prediction of the PLANCK-constrained primordial lithium abundance in the
Universe is in discordance with the observed Li abundances in warm Population
II dwarf and subgiant stars. Among the physically best motivated ideas, it has
been suggested that this discrepancy can be alleviated if the stars observed
today had undergone photospheric depletion of lithium. The cause of this
depletion is investigated by accurately tracing the behaviour of the lithium
abundances as a function of effective temperature. Globular clusters are ideal
laboratories for such an abundance analysis as the relative stellar parameters
of their stars can be precisely determined. We performed a homogeneous chemical
abundance analysis of 144 stars in the metal-poor globular cluster M30, ranging
from the cluster turnoff point to the tip of the red giant branch. NLTE
abundances for Li, Ca, and Fe were derived where possible. Stellar parameters
were derived by matching isochrones to the observed V vs V-I colour-magnitude
diagram. Independent effective temperatures were obtained from automated
profile fitting of the Balmer lines and by applying colour-T_eff calibrations
to the broadband photometry. Li abundances of the turnoff and early subgiant
stars form a thin plateau that is broken off abruptly in the middle of the SGB
as a result of the onset of Li dilution caused by the first dredge-up.
Abundance trends with effective temperature for Fe and Ca are observed and
compared to predictions from stellar structure models including atomic
diffusion and ad hoc additional mixing below the surface convection zone. The
comparison shows that the stars in M30 are affected by atomic diffusion and
additional mixing. After applying a conservative correction for atomic
diffusion, we find an initial Li abundance of A(Li) = $2.48\pm0.10$ for the
globular cluster M30.


title: Identifiability of an X-rank decomposition of polynomial maps

abstract:
  In this paper, we study a polynomial decomposition model that arises in
problems of system identification, signal processing and machine learning. We
show that this decomposition is a special case of the X-rank decomposition ---
a powerful novel concept in algebraic geometry that generalizes the tensor CP
decomposition. We prove new results on generic/maximal rank and on
identifiability of a particular polynomial decomposition model. In the paper,
we try to make results and basic tools accessible for general audience
(assuming no knowledge of algebraic geometry or its prerequisites).


title:
Electromagnetic Simulation and Design of a Novel Waveguide RF Wien
  Filter for Electric Dipole Moment Measurements of Protons and Deuterons

abstract:
  The conventional Wien filter is a device with orthogonal static magnetic and
electric fields, often used for velocity separation of charged particles. Here
we describe the electromagnetic design calculations for a novel waveguide RF
Wien filter that will be employed to solely manipulate the spins of protons or
deuterons at frequencies of about 0.1 to 2 MHz at the COoler SYnchrotron COSY
at J\"ulich. The device will be used in a future experiment that aims at
measuring the proton and deuteron electric dipole moments, which are expected
to be very small. Their determination, however, would have a huge impact on our
understanding of the universe.


title: Exact factorizations and extensions of fusion categories

abstract:
  We introduce and study the new notion of an {\em exact factorization}
$\mathcal{B}=\mathcal{A}\bullet \mathcal{C}$ of a fusion category $\mathcal{B}$
into a product of two fusion subcategories $\mathcal{A},\mathcal{C}\subseteq
\mathcal{B}$ of $\mathcal{B}$. This is a categorical generalization of the well
known notion of an exact factorization of a finite group into a product of two
subgroups. We then relate exact factorizations of fusion categories to exact
sequences of fusion categories with respect to an indecomposable module
category, which was introduced and studied by P. Etingof and the author in
\cite{EG}. We also apply our results to study extensions of a group-theoretical
fusion category by another one, provide some examples, and propose a few
natural questions.


title: Local(ish) gravity theories in conformal superspace

abstract:
  Motivated by well-known obstacles to quantum gravity, I look for the most
general geometrodynamical symmetries compatible with a reduced physical
configuration space for metric gravity. I argue that they lead either to a
completely static Universe, or one embodying spatial conformal diffeomorphisms.
Demanding locality for an action compatible with these principles determines
the sort of terms one can add, both for the purely gravitational part as well
as matter couplings. The symmetries guarantee that there are two gravitational
propagating physical degrees of freedom (and no explicit
refoliation-invariance). The simplest such system has a geometric
interpretation as a geodesic model in infinite dimensional conformal
superspace. An approximate solution to the equations of motion corresponds to a
static Bianchi IX spatial ansatz. The unique coupling to electromagnetism
forces its propagation equations to be hyperbolic, enabling us to \"build" a
standard space-time causal structure. There are, however, deviations from the
standard Maxwell equations when space-time anisotropies become too large.
Regarding quantization, with the geometric interpretation and the lack of
refoliation invariance, the path integral treatment of the symmetries becomes
much less involved than the similar approaches to GR. The symmetries form an
(infinite-dimensional) Lie algebra, and no BFV treatment is necessary. We find
that the propagator around the flat solution has up to 6-th order spatial
derivatives, giving it plausible regularization properties as in
Horava-Lifschitz.


title:
Coordination Event Detection and Initiator Identification in Time Series
  Data

abstract:
  Behavior initiation is a form of leadership and is an important aspect of
social organization that affects the processes of group formation, dynamics,
and decision-making in human societies and other social animal species. In this
work, we formalize the "Coordination Initiator Inference Problem" and propose a
simple yet powerful framework for extracting periods of coordinated activity
and determining individuals who initiated this coordination, based solely on
the activity of individuals within a group during those periods. The proposed
approach, given arbitrary individual time series, automatically (1) identifies
times of coordinated group activity, (2) determines the identities of
initiators of those activities, and (3) classifies the likely mechanism by
which the group coordination occurred, all of which are novel computational
tasks. We demonstrate our framework on both simulated and real-world data:
trajectories tracking of animals as well as stock market data. Our method is
competitive with existing global leadership inference methods but provides the
first approaches for local leadership and coordination mechanism
classification. Our results are consistent with ground-truthed biological data
and the framework finds many known events in financial data which are not
otherwise reflected in the aggregate NASDAQ index. Our method is easily
generalizable to any coordinated time-series data from interacting entities.

categories: cs.SI cs.AI cs.MA econ.EM physics.data-an


title: Growth and Division of Active Droplets: A Model for Protocells

abstract:
  It has been proposed that during the early steps in the origin of life, small
droplets could have formed via the segregation of molecules from complex
mixtures by phase separation. These droplets could have provided chemical
reaction centers. However, whether these droplets could divide and propagate is
unclear. Here we examine the behavior of droplets in systems that are
maintained away from thermodynamic equilibrium by an external supply of energy.
In these systems, droplets grow by the addition of droplet material generated
by chemical reactions. Surprisingly, we find that chemically driven droplet
growth can lead to shape instabilities that trigger the division of droplets
into two smaller daughters. Therefore, chemically active droplets can exhibit
cycles of growth and division that resemble the proliferation of living cells.
Dividing active droplets could serve as a model for prebiotic protocells, where
chemical reactions in the droplet play the role of a prebiotic metabolism.


title: The time evolution of HH 1 from four epochs of HST images

abstract:
  We present an analysis of four epochs of H$\alpha$ and [S II]
$\lambda\lambda$ 6716/6731 HST images of HH 1. For determining proper motions
we explore a new method based on analysis of spatially degraded images obtained
convolving the images with wavelet functions of chosen widths. With this
procedure we are able to generate maps of proper motion velocities along and
across the outflow axis, as well as (angularly integrated) proper motion
velocity distributions. From the four available epochs, we find the time
evolution of the velocities, intensities and spatial distribution of the line
emission. We find that over the last two decades HH 1 shows a clear
acceleration. Also, the H$\alpha$ and [S II] intensities have first dropped,
and then recovered in the more recent (2014) images. Finally, we show a
comparison between the two available HST epochs of [O III] $\lambda$ 5007 (1994
and 2014), in which we see a clear drop in the value of the [O III]/H$\alpha$
ratio.


title: McCulloch-Pitts brains and pseudorandom functions

abstract:
  In a pioneering classic, Warren McCulloch and Walter Pitts proposed a model
of the central nervous system. Motivated by EEG recordings of normal brain
activity, Chv\'atal and Goldsmith asked whether or not these dynamical systems
can be engineered to produce trajectories which are irregular, disorderly,
apparently unpredictable. We show that they cannot build weak pseudorandom
functions.


title: Back to Parmenides

abstract:
  After a brief introduction to issues that plague the realization of a theory
of quantum gravity, I suggest that the main one concerns a quantization of the
principle of relative simultaneity. This leads me to a distinction between time
and space, to a further degree than that present in the canonical approach to
general relativity. With this distinction, one can make sense of superpositions
as interference between alternative paths in the relational configuration space
of the entire Universe. But the full use of relationalism brings us to a
timeless picture of Nature, as it does in the canonical approach (which
culminates in the Wheeler-DeWitt equation). After a discussion of Parmenides
and the Eleatics' rejection of time, I show that there is middle ground between
their view of absolute timelessness and a view of physics taking place in
timeless configuration space. In this middle ground, even though change does
not fundamentally exist, the illusion of change can be recovered in a way not
permitted by Parmenides. It is recovered through a particular density
distribution over configuration space which gives rise to 'records'.
Incidentally, this distribution seems to have the potential to dissolve further
aspects of the measurement problem that can still be argued to haunt the
application of decoherence to Many-Worlds quantum mechanics. I end with a
discussion indicating that the conflict between the conclusions of this paper
and our view of the continuity of the self may still intuitively bother us.
Nonetheless, those conclusions should be no more challenging to our intuition
than Derek Parfit's thought experiments on the subject.


title: Itinerant scenario for Fe-pnictides: comparison with quantum Monte Carlo

abstract:
  Recent applications of Quantum Monte Carlo (QMC) technique to Fe-based
superconductors opened a way to directly verify the applicability of the
itinerant scenario for these systems. Fe-based superconductors undergo various
instabilities upon lowering temperature (magnetism, superconductivity,
nematicity/orbital order), and one can check whether the hierarchy of
instabilities obtained within the itinerant approach is the same as in unbiased
QMC simulations. In a recent paper [arXiv:1512:08523] the authors considered
the simplest two-band model with interaction tailored to favor orbital order.
The type of the orbital order found in QMC is different from the one found in
earlier itinerant analysis. We report the results of our calculations within
the itinerant scenario and argue that they are in perfect agreement with QMC.


title: Quark Contraction Tool -- QCT

abstract:
  We present a Mathematica package for the calculation of Wick contractions in
quantum field theories - QCT. Furthermore the package aims at automatically
generating code for the calculation of physical matrix elements, suitable for
numerical evaluation in a C++ program. To that end commonly used algebraic
manipulations for the calculation of matrix elements in lattice QCD are
implemented.


title: Rigidity of an Isometric $SL(3,\mathbb{R})$-Action

abstract:
  We characterize the universal covering of connected analytic
pseudo-Riemannian manifolds which admit a non-trivial and isometric action of
the simple Lie group $SL(3,\mathbb{R})$ with a dense orbit preserving a finite
volume. If such manifold is also weakly irreducible we prove that $M$ is
isometric to, or a quotient space of, a simple Lie group containing
$SL(3,\mathbb{R})$.


title:
Role of Dzyaloshinskii-Moriya interaction for magnetism in
  transition-metal chains at Pt step-edges

abstract:
  We explore the emergence of chiral magnetism in one-dimensional monatomic Mn,
Fe, and Co chains deposited at the Pt(664) step-edge carrying out an ab-initio
study based on density functional theory (DFT). The results are analyzed
employing several models: (i) a micromagnetic model, which takes into account
the Dzyaloshinskii-Moriya interaction (DMI) besides the spin stiffness and the
magnetic anisotropy energy, and (ii) the Fert-Levy model of the DMI for diluted
magnetic impurities in metals. Due to the step-edge geometry, the direction of
the Dzyaloshinskii vector (D-vector) is not predetermined by symmetry and
points in an off-symmetry direction. For the Mn chain we predict a long-period
cycloidal spin-spiral ground state of unique rotational sense on top of an
otherwise atomic-scale antiferromagnetic phase. The spins rotate in a plane
that is tilted relative to the Pt surface by $62^\circ$ towards the upper step
of the surface. The Fe and Co chains show a ferromagnetic ground state since
the DMI is too weak to overcome their respective magnetic anisotropy barriers.
Beyond the discussion of the monatomic chains we provide general expressions
relating ab-initio results to realistic model parameters that occur in a
spin-lattice or in a micromagnetic model. We prove that a planar homogeneous
spiral of classical spins with a given wave vector rotating in a plane whose
normal is parallel to the D-vector is an exact stationary state solution of a
spin-lattice model for a periodic solid that includes Heisenberg exchange and
DMI. The validity of the Fert-Levy model for the evaluation of micromagnetic
DMI parameters and for the analysis of ab-initio calculations is explored for
chains. The results suggest that some care has to be taken when applying the
model to infinite periodic one-dimensional systems.


title:
To Grow is Not Enough: Impact of Noise on Cell Environmental Response
  and Fitness

abstract:
  Quantitative single cell measurements have shown that cell cycle duration
(the time between cell divisions) for diverse cell types is a noisy variable.
The underlying distribution is mean scalable with a universal shape for many
cell types in a variety of environments. Here we show through both experiment
and theory that increasing the amount of noise in the regulation of the cell
cycle negatively impacts the growth rate but positively correlates with
improved cellular response to fluctuating environments. Our findings suggest
that even non-cooperative cells in exponential growth phase do not optimize
fitness through growth rate alone, but also optimize adaptability to changing
conditions. In a manner similar to genetic evolution, increasing the noise in
biochemical processes correlates with improved response of the system to
environmental changes.


title: Cross-response in correlated financial markets: individual stocks

abstract:
  Previous studies of the stock price response to trades focused on the
dynamics of single stocks, i.e. they addressed the self-response. We
empirically investigate the price response of one stock to the trades of other
stocks in a correlated market, i.e. the cross-responses. How large is the
impact of one stock on others and vice versa? -- This impact of trades on the
price change across stocks appears to be transient instead of permanent as we
discuss from the viewpoint of market efficiency. Furthermore, we compare the
self-responses on different scales and the self- and cross-responses on the
same scale. We also find that the cross-correlation of the trade signs turns
out to be a short-memory process.


title:
Causal inference for data-driven debugging and decision making in cloud
  computing

abstract:
  Cloud computing involves complex technical and economical systems and
interactions. This brings about various challenges, two of which are: (1)
debugging and control to optimize the performance of computing systems, with
the help of sandbox experiments, and (2) privacy-preserving prediction of the
cost of ``spot'' resources for decision making of cloud clients. In this paper,
we formalize debugging by counterfactual probabilities and control by
post-(soft-)interventional probabilities. We prove that counterfactuals can
approximately be calculated from a ``stochastic'' graphical causal model (while
they are originally defined only for ``deterministic'' functional causal
models), and based on this sketch a data-driven approach to address problem
(1). To address problem (2), we formalize bidding by post-(soft-)interventional
probabilities and present a simple mathematical result on approximate
integration of ``incomplete'' conditional probability distributions. We show
how this can be used by cloud clients to trade off privacy against
predictability of the outcome of their bidding actions in a toy scenario. We
report experiments on simulated and real data.


title:
Existence of SRB Measures for A Class of Partially Hyperbolic Attractors
  in Banach spaces

abstract:
  In this paper, we study the existence of SRB measures for infinite
dimensional dynamical systems in a Banach space. We show that if the system has
a partially hyperbolic attractor with nontrivial finite dimensional unstable
directions, then it has an SRB measure.


title: Randomized algorithms for finding a majority element

abstract:
  Given $n$ colored balls, we want to detect if more than $\lfloor n/2\rfloor$
of them have the same color, and if so find one ball with such majority color.
We are only allowed to choose two balls and compare their colors, and the goal
is to minimize the total number of such operations. A well-known exercise is to
show how to find such a ball with only $2n$ comparisons while using only a
logarithmic number of bits for bookkeeping. The resulting algorithm is called
the Boyer--Moore majority vote algorithm. It is known that any deterministic
method needs $\lceil 3n/2\rceil-2$ comparisons in the worst case, and this is
tight. However, it is not clear what is the required number of comparisons if
we allow randomization. We construct a randomized algorithm which always
correctly finds a ball of the majority color (or detects that there is none)
using, with high probability, only $7n/6+o(n)$ comparisons. We also prove that
the expected number of comparisons used by any such randomized method is at
least $1.019n$.


title: A Low-noise Germanium Ionization Spectrometer for Low-background Science

abstract:
  Recent progress on the development of very low noise high purity germanium
ionization spectrometers has produced an instrument of 1.2 kg mass and
excellent noise performance. The detector was installed in a low-background
cryostat intended for use in a direct detection search for low mass, WIMP dark
matter. This Transaction reports the thermal characterization of the cryostat,
specifications of the newly prepared 1.2 kg p-type point contact germanium
detector, and the spectroscopic performance of the integrated system. The
integrated detector and low background cryostat achieved
full-width-at-half-maximum noise performance of 98 eV for an electronic pulse
generator peak and 1.9 keV for the 1332 keV Co-60 gamma ray.


title:
Lead-Free Halide Double Perovskites via Heterovalent Substitution of
  Noble Metals

abstract:
  Lead-based halide perovskites are emerging as the most promising class of
materials for next generation optoelectronics. However, despite the enormous
success of lead-halide perovskite solar cells, the issues of stability and
toxicity are yet to be resolved. Here we report on the computational design and
the experimental synthesis of a new family of Pb-free inorganic halide
double-perovskites based on bismuth or antimony and noble metals. Using
first-principles calculations we show that this hitherto unknown family of
perovskites exhibits very promising optoelectronic properties, such as tunable
band gaps in the visible range and low carrier effective masses. Furthermore,
we successfully synthesize the double perovskite Cs2BiAgCl6, we perform
structural refinement using single-crystal X-ray diffraction, and we
characterize its optical properties via optical absorption and
photoluminescence measurements. This new perovskite belongs to the Fm-3m space
group, and consists of BiCl6 and AgCl6 octahedra alternating in a rock-salt
face-centered cubic structure. From UV-Vis and PL measurements we obtain an
indirect gap of 2.2 eV. The new compound is very stable under ambient
conditions.


title: Average cross-responses in correlated financial market

abstract:
  There are non-vanishing price responses across different stocks in correlated
financial markets. We further study this issue by performing different
averages, which identify active and passive cross-responses. The two average
cross-responses show different characteristic dependences on the time lag. The
passive cross-response exhibits a shorter response period with sizeable
volatilities, while the corresponding period for the active cross-response is
longer. The average cross-responses for a given stock are evaluated either with
respect to the whole market or to different sectors. Using the response
strength, the influences of individual stocks are identified and discussed.
Moreover, the various cross-responses as well as the average cross-responses
are compared with the self-responses. In contrast, the short memory of trade
sign cross-correlation for stock pairs, the sign cross-correlation has long
memory when averaged over different pairs of stocks.


title: Classification of Constructible Cosheaves

abstract:
  In this paper we prove an equivalence theorem originally observed by Robert
MacPherson. On one side of the equivalence is the category of cosheaves that
are constructible with respect to a locally cone-like stratification. Our
constructibility condition is new and only requires that certain inclusions of
open sets are sent to isomorphisms. On the other side of the equivalence is the
category of functors from the entrance path category, which has points for
objects and certain homotopy classes of paths for morphisms. When our
constructible cosheaves are valued in $\mathsf{Set}$ we prove an additional
equivalence with the category of stratified coverings.


title:
Theoretical investigation of electron-hole complexes in anisotropic
  two-dimensional materials

abstract:
  Trions and biexcitons in anisotropic two-dimensional materials are
investigated within an effective mass theory. Explicit results are obtained for
phosphorene and arsenene, materials that share features such as a direct
quasi-particle gap and anisotropic conduction and valence bands. Trions are
predicted to have remarkably high binding energies and an elongated
electron-hole structure with a preference for alignment along the armchair
direction, where the effective masses are lower. We find that biexciton binding
energies are also notably large, especially for monolayer phosphorene, where
they are found to be twice as large as those for typical monolayer transition
metal dichalcogenides.


title:
Web matrices: structural properties and generating combinatorial
  identities

abstract:
  In this paper we present new results for the combinatorics of web diagrams
and web worlds. These are discrete objects that arise in the physics of
calculating scattering amplitudes in non-abelian gauge theories. Web-colouring
and web-mixing matrices (collectively known as web matrices) are indexed by
ordered pairs of web-diagrams and contain information relating the number of
colourings of the first web diagram that will produce the second diagram.
  We introduce the black diamond product on power series and show how it
determines the web-colouring matrix of disjoint web worlds. Furthermore, we
show that combining known physical results with the black diamond product gives
a new technique for generating combinatorial identities. Due to the complicated
action of the product on power series, the resulting identities appear highly
non-trivial.
  We present two results to explain repeated entries that appear in the web
matrices. The first of these shows how diagonal web matrix entries will be the
same if the comparability graphs of their associated decomposition posets are
the same. The second result concerns general repeated entries in conjunction
with a flipping operation on web diagrams.
  We present a combinatorial proof of idempotency of the web-mixing matrices,
previously established using physical arguments only. We also show how the
entries of the square of the web-colouring matrix can be achieved by a linear
transformation that maps the standard basis for formal power series in one
variable to a sequence of polynomials. We look at one parameterized web world
that is related to indecomposable permutations and show how determining the
web-colouring matrix entries in this case is equivalent to a combinatorics on
words problem.


title: Does thiosemicarbazide lead nitrate (TSLN) crystal exist?

abstract:
  The authors of a recent paper (Optik 125 (2014) 2022-2025) claim to have
grown a so called thiosemicarbazide lead nitrate (TSLN) crystal by the slow
evaporation method. In this comment we prove that TSLN is actually
thiosemicarbazide.


title: Unphysical Poles of Domain Wall Fermions at finite $L_s$

abstract:
  We investigate the origin and behavior of oscillations observed in the hadron
correlators constructed from the domain wall fermion (DWF) for different
parameters involved in lattice QCD simulations. This oscillatory behavior at
early time slices hinders the extraction of excited states in hadron
spectroscopy. Furthermore, the deviation from exponential decay may have a
significant impact on fermion loop calculations performed on the lattice. We
present results for several well-known implementations of the DWF actions. We
extend the study of Shamir DWF action to include Bori\c{c}i and M\"{o}bius DWF
actions by analyzing the poles of 4D quark propagator. For each action
considered, we find an unphysical mode when analyzing the pole structure of the
free DWF propagator for a finite extent of the $5^{\text{th}}$ dimension $L_s$,
and we show that this mode is responsible for the oscillatory behavior observed
in hadron correlators. We have performed numerical checks on these results and
have found that the presence of oscillatory behavior is sensitive to the DWF
parameters $a_5$, $b_5$, $c_5$ and DW height $M$. To minimize oscillations, our
results suggest that one should choose $M a_5<1$ for the Shamir and Bori\c{c}i
DWFs, and $M(b_5-c_5)<1$ for M\"{o}bius DWF when $M>1$. For each calculation
considered, the Bor\c{c}i DWF displayed the smallest magnitude of oscillation
when compared to the Shamir and M\"{o}bius DWF actions using the same input
parameters.


title: Phase Retrieval of Real-Valued Signals in a Shift-Invariant Space

abstract:
  Phase retrieval arises in various fields of science and engineering and it is
well studied in a finite-dimensional setting. In this paper, we consider an
infinite-dimensional phase retrieval problem to reconstruct real-valued signals
living in a shift-invariant space from its phaseless samples taken either on
the whole line or on a set with finite sampling rate. We find the equivalence
between nonseparability of signals in a linear space and its phase
retrievability with phaseless samples taken on the whole line. For a spline
signal of order $N$, we show that it can be well approximated, up to a sign,
from its noisy phaseless samples taken on a set with sampling rate $2N-1$. We
propose an algorithm to reconstruct nonseparable signals in a shift-invariant
space generated by a compactly supported continuous function. The proposed
algorithm is robust against bounded sampling noise and it could be implemented
in a distributed manner.