title:
Built-in Foreground/Background Prior for Weakly-Supervised Semantic
  Segmentation

abstract:
  Pixel-level annotations are expensive and time consuming to obtain. Hence,
weak supervision using only image tags could have a significant impact in
semantic segmentation. Recently, CNN-based methods have proposed to fine-tune
pre-trained networks using image tags. Without additional information, this
leads to poor localization accuracy. This problem, however, was alleviated by
making use of objectness priors to generate foreground/background masks.
Unfortunately these priors either require training pixel-level
annotations/bounding boxes, or still yield inaccurate object boundaries. Here,
we propose a novel method to extract markedly more accurate masks from the
pre-trained network itself, forgoing external objectness modules. This is
accomplished using the activations of the higher-level convolutional layers,
smoothed by a dense CRF. We demonstrate that our method, based on these masks
and a weakly-supervised loss, outperforms the state-of-the-art tag-based
weakly-supervised semantic segmentation techniques. Furthermore, we introduce a
new form of inexpensive weak supervision yielding an additional accuracy boost.


title:
Evidence for a dynamically refracted primary bow in weakly bound $^9$Be
  rainbow scattering from $^{16}$O

abstract:
  We present for the first time evidence for the existence of a dynamically
refracted primary bow for $^{9}$Be+$^{16}$O scattering. This is demonstrated
through the use of coupled channel calculations with an extended double folding
potential derived from the density-dependent effective two-body force and
precise microscopic cluster wave functions for $^{9}$Be. The calculations
reproduce the experimental Airy structure in $^{9}$Be+$^{16}$O scattering
well.It is found that coupling of a weakly bound $^{9}$Be nucleus to excited
states plays the role of a booster lens, dynamically enhancing the refraction
over the {\it static} refraction due to the Luneburg lens mean field potential
between the ground states of $^{9}$Be and $^{16}$O.


title:
Do Mathematicians, Economists and Biomedical Scientists Trace Large
  Topics More Strongly Than Physicists?

abstract:
  In this work, we extend our previous work on largeness tracing among
physicists to other fields, namely mathematics, economics and biomedical
science. Overall, the results confirm our previous discovery, indicating that
scientists in all these fields trace large topics. Surprisingly, however, it
seems that researchers in mathematics tend to be more likely to trace large
topics than those in the other fields. We also find that on average, papers in
top journals are less largeness-driven. We compare researchers from the USA,
Germany, Japan and China and find that Chinese researchers exhibit consistently
larger exponents, indicating that in all these fields, Chinese researchers
trace large topics more strongly than others. Further correlation analyses
between the degree of largeness tracing and the numbers of authors,
affiliations and references per paper reveal positive correlations -- papers
with more authors, affiliations or references are likely to be more
largeness-driven, with several interesting and noteworthy exceptions: in
economics, papers with more references are not necessary more largeness-driven,
and the same is true for papers with more authors in biomedical science. We
believe that these empirical discoveries may be valuable to science
policy-makers.


title:
G345.45+1.50: An expanding ring-like structure with massive star
  formation

abstract:
  Ring-like structures in the ISM are commonly associated with high-mass stars.
Kinematic studies of large structures in GMCs toward these ring-like structures
may help us to understand how massive stars form. The origin and properties of
the ring-like structure G345.45+1.50 is investigated through observations of
the 13CO(3-2) line. The aim of the observations is to determine the kinematics
in the region and to compare physical characteristics estimated from gas
emission with those previously determined using dust continuum emission. The
13CO(3-2) line was mapped toward the whole ring using the APEX telescope. The
ring is found to be expanding with a velocity of 1.0 km/s, containing a total
mass of 6.9e3 Msun, which agrees well with that determined using 1.2 mm dust
continuum emission. An expansion timescale of 3e6 yr and a total energy of 7e46
erg are estimated. The origin of the ring might have been a supernova
explosion, since a 35.5 cm source, J165920-400424, is located at the center of
the ring without an infrared counterpart. The ring is fragmented, and 104
clumps were identified with diameters of between 0.3 and 1.6 pc, masses of
between 2.3 and 7.5e2 Msun, and densities of between 1.0e2 and 1.0e4 cm^-3. At
least 18% of the clumps are forming stars, as is shown in infrared images.
Assuming that the clumps can be modeled as Bonnor-Ebert spheres, 13 clumps are
collapsing, and the rest of them are in hydrostatic equilibrium with an
external pressure with a median value of 4e4 K cm^-3. In the region, the
molecular outflow IRAS 16562-3959 is identified, with a velocity range of 38.4
km/s, total mass of 13 Msun, and kinematic energy of 7e45 erg. Finally, five
filamentary structures were found at the edge of the ring with an average size
of 3 pc, a width of 0.6 pc, a mass of 2e2 Msun, and a column density of 6e21
cm^-2.


title: Schwarz maps of Algebraic Linear Ordinary Differential Equations

abstract:
  A linear ordinary differential equation is called algebraic if all its
solution are algebraic over its field of definition. In this paper we solve the
problem of finding closed form solution to algebraic linear ordinary
differential equations in terms of standard equations. Furthermore, we obtain a
method to compute all algebraic linear ordinary differential equations with
rational coefficients by studying their associated Schwarz map through the
Picard-Vessiot Theory.


title: Least Ambiguous Set-Valued Classifiers with Bounded Error Levels

abstract:
  In most classification tasks there are observations that are ambiguous and
therefore difficult to correctly label. Set-valued classifiers output sets of
plausible labels rather than a single label, thereby giving a more appropriate
and informative treatment to the labeling of ambiguous instances. We introduce
a framework for multiclass set-valued classification, where the classifiers
guarantee user-defined levels of coverage or confidence (the probability that
the true label is contained in the set) while minimizing the ambiguity (the
expected size of the output). We first derive oracle classifiers assuming the
true distribution to be known. We show that the oracle classifiers are obtained
from level sets of the functions that define the conditional probability of
each class. Then we develop estimators with good asymptotic and finite sample
properties. The proposed estimators build on existing single-label classifiers.
The optimal classifier can sometimes output the empty set, but we provide two
solutions to fix this issue that are suitable for various practical needs.


title:
Large-Scale Antenna-Assisted Grant-free Non-Orthogonal Multiple Access
  via Compressed Sensing

abstract:
  Support massive connectivity is an important requirement in 5G wireless
communication system. For massive Machine Type Communication (MTC) scenario,
since the network is expected to accommodate a massive number of MTC devices
with sparse short message, the multiple access scheme like current LTE uplink
would not be suitable. In order to reduce the signaling overhead, we consider
an grant-free multiple access system, which requires the receiver facilitate
activity detection, channel estimation, and data decoding in "one shot" and
without the knowledge of active user's pilots. However, most of the "one shot"
communication research haven't considered the massive MIMO scenario. In this
work we propose a Multiple Measurement Model (MMV) model based Massive MIMO and
exploit the covariance matrix of the measurements to confirm a high activity
detection rate.


title: The Hamilton-Waterloo Problem for $C_3$-factors and $C_n$-factors

abstract:
  The Hamilton-Waterloo problem asks for a 2-factorization of $K_v$ (for $v$
odd) or $K_v$ minus a $1$-factor (for $v$ even) into $C_m$-factors and
$C_n$-factors. We completely solve the Hamilton-Waterloo problem in the case of
$C_3$-factors and $C_n$-factors for $n=4,5,7$.


title: Brauer group of moduli of Higgs bundles and connections

abstract:
  Given a compact Riemann surface $X$ and a semisimple affine algebraic group
$G$ defined over $\mathbb C$, there are moduli spaces of Higgs bundles and of
connections associated to $(X,\, G)$. We compute the Brauer group of the smooth
locus of these varieties.


title: Kinematics of the Galactic disk from LAMOST Dwarf sample

abstract:
  Based on the LAMOST survey and Sloan Digital Sky Survey (SDSS), we use
low-resolution spectra of 130,043 F/G-type dwarf stars to study the kinematics
and metallicity properties of the Galactic disk. Our study shows that the stars
with poorer metallicity and larger vertical distance from Galactic plane tend
to have larger eccentricity and velocity dispersion. After separating the
sample stars into likely thin-disk and thick-disk sub-sample, we find that
there exits a negative gradient of rotation velocity $V_{\phi}$ with
metallicity [Fe/H] for the likely thin-disk sub-sample, and the thick-disk
sub-sample exhibit a larger positive gradient of rotation velocity with
metallicity. By comparing with model prediction, we consider the radial
migration of stars appears to have influenced on the thin-disk formation. In
addition, our results shows that the observed thick-disk stellar orbital
eccentricity distribution peaks at low eccentricity ($e \sim 0.2$) and extends
to a high eccentricity ($e \sim 0.8$). We compare this result with four
thick-disk formation simulated models, and it imply that our result is
consistent with gas-rich merger model.


title:
Observation of the Goos-H\"anchen shift in graphene via weak
  measurements

abstract:
  We report the observation of the Goos-H\"anchen effect in graphene via a weak
value amplification scheme. We demonstrate that the amplified Goos-H\"anchen
shift in weak measurements is sensitive to the variation of graphene layers.
Combining the Goos-H\"anchen effect with weak measurements may provide
important applications in characterizing the parameters of graphene.


title:
Finding resource states of measurement-based quantum computing is harder
  than quantum computing

abstract:
  Measurement-based quantum computing enables universal quantum computing with
only adaptive single-qubit measurements on certain many-qubit states, such as
the graph state, the Affleck-Kennedy-Lieb-Tasaki (AKLT) state, and several
tensor-network states. Finding new resource states of measurement-based quantum
computing is a hard task, since for a given state there are exponentially many
possible measurement patterns on the state. In this paper, we consider the
problem of deciding, for a given state and a set of unitary operators, whether
there exists a way of measurement-based quantum computing on the state that can
realize all unitaries in the set, or not. We show that the decision problem is
QCMA-hard, which means that finding new resource states of measurement-based
quantum computing is harder than quantum computing itself (unless BQP is equal
to QCMA). We also derive an upperbound of the decision problem: the problem is
in a quantum version of the second level of the polynomial hierarchy.

categories: quant-ph cond-mat.stat-mech cond-mat.str-el cs.CC


title:
Wind, jet, hybrid corona and hard X-ray flares: multiwavelength
  evolution of GRO J1655-40 during the 2005 outburst rise

abstract:
  We have investigated the complex multiwavelength evolution of GRO J1655-40
during the rise of its 2005 outburst. We detected two hard X-ray flares, the
first one during the transition from the soft state to the ultra-soft state,
and the second one in the ultra-soft state. The first X-ray flare coincided
with an optically thin radio flare. We also observed a hint of increased radio
emission during the second X-ray flare. To explain the hard flares without
invoking a secondary emission component, we fit the entire data set with the
eqpair model. This single, hybrid Comptonization model sufficiently fits the
data even during the hard X-ray flares if we allow reflection fractions greater
than unity. In this case, the hard X-ray flares correspond to a Comptonizing
corona dominated by non-thermal electrons. The fits also require absorption
features in the soft and ultra-soft state which are likely due to a wind. In
this work we show that the wind and the optically thin radio flare co-exist.
Finally, we have also investigated the radio to optical spectral energy
distribution, tracking the radio spectral evolution through the quenching of
the compact jet and rise of the optically thin flare, and interpreted all data
using state transition models.


title: Wilsonian Effective Action of Superstring Theory

abstract:
  By integrating out the heavy fields in type II or heterotic string field
theory one can construct the effective action for the light fields. This
effective theory inherits all the algebraic structures of the parent theory and
the effective action automatically satisfies the Batalin-Vilkovisky quantum
master equation. This theory is manifestly ultraviolet finite, has only light
fields as its explicit degrees of freedom, and the Feynman diagrams of this
theory reproduce the exact scattering amplitudes of light states in string
theory to any arbitrary order in perturbation theory. Furthermore in this
theory the degrees of freedom of light fields above certain energy scale are
also implicitly integrated out. This energy scale is determined by a particular
parameter labelling a family of equivalent actions, and can be made arbitrarily
low, leading to the interpretation of the effective action as the Wilsonian
effective action.


title:
Current-temperature scaling for a Schottky interface with non-parabolic
  energy dispersion

abstract:
  In this paper, we study the Schottky transport in narrow-gap semiconductor
and few-layer graphene in which the energy dispersions are highly
non-parabolic. We propose that the contrasting current-temperature scaling
relation of $J\propto T^2$ in the conventional Schottky interface and $J\propto
T^3$ in graphene-based Schottky interface can be reconciled under Kane's
$\mathbf{k} \cdot \mathbf{p}$ non-parabolic band model for narrow-gap
semiconductor. Our new model suggests a more general form of $J\propto
\left(T^2 + \gamma k_BT^3 \right)$, where the non-parabolicty parameter,
$\gamma$, provides a smooth transition from $T^2$ to $T^3$ scaling. For
few-layer graphene, it is found that $N$-layers graphene with $ABC$-stacking
follows $J\propto T^{2/N+1}$ while $ABA$-stacking follows a universal form of
$J\propto T^3$ regardless of the number of layers. Intriguingly, the Richardson
constant extracted from the Arrhenius plot using an incorrect scaling relation
disagrees with the actual value by two orders of magnitude, suggesting that
correct models must be used in order to extract important properties for many
novel Schottky devices.


title:
Network clustering and community detection using modulus of families of
  loops

abstract:
  We study the structure of loops in networks using the notion of modulus of
loop families. We introduce a new measure of network clustering by quantifying
the richness of families of (simple) loops. Modulus tries to minimize the
expected overlap among loops by spreading the expected link-usage optimally. We
propose weighting networks using these expected link-usages to improve
classical community detection algorithms. We show that the proposed method
enhances the performance of certain algorithms, such as spectral partitioning
and modularity maximization heuristics, on standard benchmarks.


title: A case study of algorithm selection for the traveling thief problem

abstract:
  Many real-world problems are composed of several interacting components. In
order to facilitate research on such interactions, the Traveling Thief Problem
(TTP) was created in 2013 as the combination of two well-understood
combinatorial optimization problems.
  With this article, we contribute in four ways. First, we create a
comprehensive dataset that comprises the performance data of 21 TTP algorithms
on the full original set of 9720 TTP instances. Second, we define 55
characteristics for all TPP instances that can be used to select the best
algorithm on a per-instance basis. Third, we use these algorithms and features
to construct the first algorithm portfolios for TTP, clearly outperforming the
single best algorithm. Finally, we study which algorithms contribute most to
this portfolio.


title: Stochastic Discrete Hamiltonian Variational Integrators

abstract:
  Variational integrators are derived for structure-preserving simulation of
stochastic Hamiltonian systems with a certain type of multiplicative noise
arising in geometric mechanics. The derivation is based on a stochastic
discrete Hamiltonian which approximates a type-II stochastic generating
function for the stochastic flow of the Hamiltonian system. The generating
function is obtained by introducing an appropriate stochastic action functional
and its corresponding variational principle. Our approach permits to recast in
a unified framework a number of integrators previously studied in the
literature, and presents a general methodology to derive new
structure-preserving numerical schemes. The resulting integrators are
symplectic; they preserve integrals of motion related to Lie group symmetries;
and they include stochastic symplectic Runge-Kutta methods as a special case.
Several new low-stage stochastic symplectic methods of mean-square order 1.0
derived using this approach are presented and tested numerically to demonstrate
their superior long-time numerical stability and energy behavior compared to
nonsymplectic methods.

categories: math.NA math-ph math.DS math.MP math.PR math.SG


title:
The Semantic Knowledge Graph: A compact, auto-generated model for
  real-time traversal and ranking of any relationship within a domain

abstract:
  This paper describes a new kind of knowledge representation and mining system
which we are calling the Semantic Knowledge Graph. At its heart, the Semantic
Knowledge Graph leverages an inverted index, along with a complementary
uninverted index, to represent nodes (terms) and edges (the documents within
intersecting postings lists for multiple terms/nodes). This provides a layer of
indirection between each pair of nodes and their corresponding edge, enabling
edges to materialize dynamically from underlying corpus statistics. As a
result, any combination of nodes can have edges to any other nodes materialize
and be scored to reveal latent relationships between the nodes. This provides
numerous benefits: the knowledge graph can be built automatically from a
real-world corpus of data, new nodes - along with their combined edges - can be
instantly materialized from any arbitrary combination of preexisting nodes
(using set operations), and a full model of the semantic relationships between
all entities within a domain can be represented and dynamically traversed using
a highly compact representation of the graph. Such a system has widespread
applications in areas as diverse as knowledge modeling and reasoning, natural
language processing, anomaly detection, data cleansing, semantic search,
analytics, data classification, root cause analysis, and recommendations
systems. The main contribution of this paper is the introduction of a novel
system - the Semantic Knowledge Graph - which is able to dynamically discover
and score interesting relationships between any arbitrary combination of
entities (words, phrases, or extracted concepts) through dynamically
materializing nodes and edges from a compact graphical representation built
automatically from a corpus of data representative of a knowledge domain.


title:
Strong ferromagnetic exchange interaction in the parent state of the
  superconductivity in BaFe$_2$S$_3$

abstract:
  Inelastic neutron scattering measurements have been performed to investigate
the spin waves of the quasi-one-dimensional antiferromagnetic ladder compound
BaFe$_2$S$_3$, where a superconducting transition was observed under pressure
[H. Takahashi {\it et al.}, Nat. Mater. 14, 1008-1012 (2015); T. Yamauchi {\it
et al.}, Phys. Rev. Lett. 115, 246402 (2015)]. By fitting the spherically
averaged experimental data collected on a powder sample to a Heisenberg
Hamiltonian, we find that the one-dimensional antiferromagnetic ladder exhibits
a strong nearest neighbor ferromagnetic exchange interaction ($SJ_R=-71\pm4$
meV) along the rung direction, an antiferromagnetic $SJ_L=49\pm3$ meV along the
leg direction and a ferromagnetic $SJ_2=-15\pm2$ meV along the diagonal
direction. Our data demonstrate that the antiferromagnetic spin excitations are
a common characteristic for the iron-based superconductors, while specific
relative values for the exchange interactions do not appear to be unique for
the parent states of the superconducting materials.


title:
Consistent description of 12C and 16O using finite range three-body
  interaction

abstract:
  Consistent description of 12C and 16O has been a long standing problem of
microscopic alpha cluster models, where the wave function is fully
antisymmetrized and the effective interaction is applied not between alpha
clusters but between nucleons. When the effective interaction is designed to
reproduce the binding energy of 16O (four alpha), the binding energy of 12C
(three alpha) becomes underbound by about 10 MeV. In the present study, by
taking into account the coupling with the jj-coupling shell model components
and utilizing Tohsaki interaction, which is phenomenological but has
finite-range three-body interaction terms, we show that consistent
understanding of these nuclei can be achieved. The original Tohsaki interaction
gives small overbound of about 3 MeV for 16O, and this is improved by slightly
modifying three-body Majorana exchange parameter. Also, the coupling with the
jj-coupling shell model wave function strongly contributes to the increase of
the binding energy of 12C. So far the application of Tohsaki interaction has
been limited to 4N nuclei, and here, we add Bartlet and Heisenberg exchange
terms in the two-body interaction for the purpose of applying it to
neutron-rich systems, and it is applied to 6He.


title:
Projective method of multipliers for linearly constrained convex
  minimization

abstract:
  We present a method for solving linearly constrained convex optimization
problems, which is based on the application of known algorithms for finding
zeros of the sum of two monotone operators (presented by Eckstein and Svaiter)
to the dual problem. We establish convergence rates for the new method, and we
present applications to TV denoising and compressed sensing problems.


title:
Challenges and constraints of dynamically emerged source and sink in
  atomtronic circuits: From closed-system to open-system approaches

abstract:
  While batteries offer electronic source and sink in electronic devices,
atomic analogues of source and sink and their theoretical descriptions have
been a challenge in cold-atom systems. Here we consider dynamically emerged
local potentials as controllable source and sink for bosonic atoms. Although a
sink potential can collect bosons in equlibrium and indicate its usefulness in
the adiabatic limit, sudden switching of the potential exhibits low
effectiveness in pushing bosons into it. This is due to conservation of energy
and particle in isolated systems such as cold atoms. By varying the potential
depth and interaction strength, the systems can further exhibit averse
response, where a deeper emerged potential attracts less bosonic atoms into it.
To explore possibilities for improving the effectiveness, we investigate what
types of system-environment coupling can help bring bosons into a dynamically
emerged sink, and a Lindblad operator corresponding to local cooling is found
to serve the purpose.


title: Explosive Phase Transition in a Majority-Vote Model with Inertia

abstract:
  We generalize the original majority-vote model by incorporating an inertia
into the microscopic dynamics of the spin flipping, where the spin-flip
probability of any individual depends not only on the states of its neighbors,
but also on its own state. Surprisingly, the order-disorder phase transition is
changed from a usual continuous type to a discontinuous or an explosive one
when the inertia is above an appropriate level. A central feature of such an
explosive transition is a strong hysteresis behavior as noise intensity goes
forward and backward. Within the hysteresis region, a disordered phase and two
symmetric ordered phases are coexisting and transition rates between these
phases are numerically calculated by a rare-event sampling method. A mean-field
theory is developed to analytically reveal the property of this phase
transition.


title:
Spin-resolved orbital magnetization in Rashba two-dimensional electron
  gas

abstract:
  We calculate orbital spin-dependent magnetization in a two-dimensional
electron gas with spin-orbit interaction of Rashba type. Such an orbital
magnetization is admitted by the time-reversal symmetry of the system, and
gives rise to spin currents when the system is not in thermal equilibrium. The
theoretical approach is based on the linear response theory and the Matsubara
Green's function formalism. To account for the spin-resolved orbital
magnetization a spin-dependent vector potential has been introduced. The spin
currents which appear in thermal nonequilibrium due to the spin-resolved
orbital magnetization play an important role in the spin Nernst effect, and
have to be included in order to correctly describe the low-temperature spin
Nernst conductivity.


title: Turbulence as Information

abstract:
  A message of any sort can be regarded as a source of information. Claude. E.
Shannon showed in the last century that information ("what we don't already
know") is equivalent to the entropy as defined in statistical mechanics. A
string of experimental observations is like a succession of words; they both
convey information and can be characterized by their entropy. For the fluid
flow measurements and simulations to be discussed here (pipe and soap film
flow, GOY model), the entropy depends on controllable parameters such as the
Reynolds number. The information theory approach is applicable to measurements
of any type including those governed by intractable equations or systems where
the governing equations are not known. This contribution is dedicated to the
memory of Leo Kadanoff, an inspiring teacher and one of the most important
scientific leaders of the last half century.


title:
High pressure structural, elastic and vibrational properties of green
  energetic oxidizer ammonium dinitramide

abstract:
  Ammonium DiNitramide (ADN) is one of the most promising green energetic
oxidizers for future rocket propellant formulations. In the present work, we
report a detailed theoretical study on structural, elastic, and vibrational
properties of the emerging oxidizer under hydrostatic compression using various
dispersion correction methods to capture weak intermolecular (van der Waals and
hydrogen bonding) interactions. The calculated ground state lattice parameters,
axial compressibilities, and equation of state are in good accord with the
available experimental results. Strength of intermolecular interactions has
been correlated using the calculated compressibility curves and elastic moduli.
Apart from this, we also observe discontinuities in the structural parameters
and elastic constants as a function of pressure. Pictorial representation and
quantification of intermolecular interactions are described by the 3D Hirshfeld
surfaces and 2D finger print maps. In addition, the computed infra-red (IR)
spectra at ambient pressure reveal that ADN is found to have more hygroscopic
nature over Ammonium Perchlorate (AP) due to the presence of strong hydrogen
bonding. Pressure dependent IR spectra show blue- and red-shift of bending and
stretching frequencies which leads to weakening and strengthening of the
hydrogen bonding below and above 5 GPa, respectively. The abrupt changes in the
calculated structural, mechanical, and IR spectra suggest that ADN might
undergo a first order structural transformation to a high pressure phase around
5-6 GPa. From the predicted detonation properties, ADN is found to have high
and low performance characteristics when compared with ammonium based energetic
oxidizers and well-known secondary explosives, respectively.


title:
Ab-initio study of structural, vibrational and optical properties of
  solid oxidizers

abstract:
  We report the structural, elastic and vibrational properties of five
ionic-molecular solid oxidizers MNO$_3$ (M = Li, Na, K) and MClO$_3$ (M = Na,
K). By treating long range electron-correlation effects, dispersion corrected
method leads to more accurate predictions of structural properties and phase
stability of KNO$_3$ polymorphs. The obtained elastic moduli show soft nature
of these materials and are consistent with Ultrasonic Pulse Echo measurements.
We made a complete assignment of vibrational modes which are in good accord
with available experimental results. From calculated IR and Raman spectra, it
is found that the vibrational frequencies show a red-shift from Li -> Na -> K
(Na -> K) and N -> Cl for nitrates (chlorates) due to increase in mass of metal
and non-metal atoms, respectively. The calculated electronic structure using
recently developed Tran-Blaha modified Becke-Johnson potential show that the
materials are wide band gap insulators with predominant ionic bonding between
M$^+$ (metal) and NO$_3^-$ /ClO$_3^-$ ions and covalent bonding (N-O and Cl-O)
within nitrate and chlorate anionic group. From the calculated optical spectra,
we observe that electric-dipole transitions are due to nitrate/chlorate group
below 20 eV and cationic transitions occur above 20 eV. The calculated
reflectivity spectra are consistent with the available experimental spectra.


title: On thermal corrections to near-threshold annihilation

abstract:
  We consider non-relativistic "dark" particles interacting through gauge boson
exchange. At finite temperature, gauge exchange is modified in many ways:
virtual corrections lead to Debye screening; real corrections amount to
frequent scatterings of the heavy particles on light plasma constituents;
mixing angles change. In a certain temperature and energy range, these effects
are of order unity. Taking them into account in a resummed form, we estimate
the near-threshold spectrum of kinetically equilibrated annihilating TeV scale
particles. Weakly bound states are shown to "melt" below freeze-out, whereas
with attractive strong interactions, relevant e.g. for gluinos, bound states
boost the annihilation rate by a factor 4...80 with respect to the Sommerfeld
estimate, thereby perhaps helping to avoid overclosure of the universe.
Modestly non-degenerate dark sector masses and a way to combine the
contributions of channels with different gauge and spin structures are also
discussed.


title: 868 MHz Wireless Sensor Network - A Study

abstract:
  Today 2.4 GHz based wireless sensor networks are increasing at a tremendous
pace, and are seen in widespread applications. Product innovation and support
by many vendors in 2.4 GHz makes it a preferred choice, but the networks are
prone to issues like interference, and range issues. On the other hand, the
less popular 868 MHz in the ISM band has not seen significant usage. In this
paper we explore the use of 868 MHz channel to implement a wireless sensor
network, and study the efficacy of this channel


title: Cyclic subgroup commutativity degrees of finite groups

abstract:
  In this paper we introduce and study the concept of cyclic subgroup
commutativity degree of a finite group $G$. This quantity measures the
probability of two random cyclic subgroups of $G$ commuting. Explicit formulas
are obtained for some particular classes of groups. A criterion for a finite
group to be an Iwasawa group is also presented.


title: Rotating artificial gauge magnetic and electric fields

abstract:
  We consider the creation of artificial gauge magnetic and electric fields
created when a two-level atom interacts with an optical Ferris wheel light
field.These fields have the spatial structure of the optical Ferris wheel field
intensity profile. If this optical field pattern is made to rotate in space
then we have the creation of artificial electromagnetic fields which propagate
in closed paths. The properties of such fields are presented and discussed


title: Superradiant laser: Effect of long-ranged dipole-dipole interaction

abstract:
  We theoretically investigate the effect of long-ranged dipole-dipole
interaction (LRDDI) on a superradiant laser (SL). This effect is induced from
the atom-photon interaction in the dissipation process. In the bad-cavity limit
usually performed to initiate SL, we demonstrate that cavity photon number
oscillates as an inter-particle distance of the atoms varies. Similarly the
atom-atom coherence alternates with signs, showing critical transitions
alternatively in SL operations. This suggests a complexity of the collective
effect emerging in a large ensemble of atoms. Therefore this effect in a SL can
not be simply interpreted by only a part of the whole ensemble. We numerically
solve for a steady state SL including the spatially-dependent LRDDI, and locate
the maximal cavity photon number and the minimal spectral linewidth
respectively at the optimal atomic separations in the setting of an equidistant
atomic array. The scaling of a finite number of atoms shows an outperformed
steady state SL than the one without LRDDI, which allows for probing narrow
atomic transitions and is potentially useful for precision measurements and
next generation optical clocks.


title:
Observation of the $^1$S$_0$ to $^3$D$_1$ clock transition in
  $^{175}$Lu$^+$

abstract:
  We report the first laser spectroscopy of the $^1$S$_0$ to $^3$D$_1$ clock
transition in $^{175}$Lu$^+$. Clock operation is demonstrated on three pairs of
Zeeman transitions, one pair from each hyperfine manifold of the $^3$D$_1$
term. We measure the hyperfine intervals of the $^3$D$_1$ to 10 ppb uncertainty
and infer the optical frequency averaged over the three hyperfine transitions
to be 353.639 915 952 2 (6) THz. The lifetime of the $^3$D$_1$ state is
inferred to be $174^{+23}_{-32}$ hours from the M1 coupling strength.


title:
Attitude toward mathematics among the students at Nazarbayev University
  Foundation Year Programme

abstract:
  This article investigates the attitude toward mathematics among the students
enrolled in the Foundation Year Programme at Nazarbayev University. The study
is conducted quantitatively and an inventory developed by Tapia and Marsh II is
adopted in this research. The inventory consists of 40 statements on the
five-point Likert scale. Gender, specialization and final high school score in
mathematics are collected. The number of valid returned questionnaires is 108.
There are 55 males, 53 females, 73 Mathematical-Physics (MP), 22
Biology-Chemistry (BC) and 13 International Relations-Economics (IRE) students.
Generally, they have a positive attitude toward mathematics, with the score
mean and standard deviation are 3.999 and 0.531 out of five, respectively. We
confirm a hypothesis on a positive correlation between previous high
achievement in mathematics and favorable attitude toward it. The correlation
value is $r = 0.300$, its effect size is medium and it is extremely significant
($p$-value $= 0.0008 < 0.001$). There is no significant difference between male
and female students in terms of their attitude toward mathematics ($t =
0.6804$, $p$-value $= 0.2489 > 0.05$). There is a very significant difference
between students who specialize in IRE and MP in terms of their attitude toward
mathematics ($F(2,105) = 5.6848$, $p$-value $= 0.0045 < 0.01$).


title:
Linear Game Theory : Reduction of complexity by decomposing large games
  into partial games

abstract:
  With increasing game size, a problem of computational complexity arises. This
is especially true in real world problems such as in social systems, where
there is a significant population of players involved in the game, and the
complexity problem is critical. Previous studies in algorithmic game theory
propose succinct games that enable small descriptions of payoff matrices and
reduction of complexities. However, some of the suggested compromises lose
generality with strict assumptions such as symmetries in utility functions and
cannot be applied to the full range of real world problems that may be
presented. Graphical games are relatively promising, with a good balance
between complexity and generality. However, they assume a given graph structure
of players' interactions and cannot be applied to games without such known
graphs. This study proposes a method to identify an interaction graph between
players and subsequently decompose games into smaller components by cutting out
weak interactions for the purpose of reducing complexity. At the beginning,
players' mutual dependencies on their utilities are quantified as
variance-covariance matrices among players. Then, the interaction graphs among
players are identified by solving eigenvalue problems. Players' interactions
are further decomposed into linear combinations of games. This helps to find a
consistent equilibrium, which is a Nash equilibrium specified by the
decomposition, with reduced computational complexity. Finally, experiments on
simple example games are shown to verify the proposed method.


title: Fidelity of dynamical maps

abstract:
  We introduce the concept of fidelity for dynamical maps in an open quantum
system scenario. We derive an inequality linking this quantity to the
distinguishability of the inducing environmental states. Our inequality imposes
constraints on the allowed set of dynamical maps arising from the microscopic
description of system plus environment. Remarkably, the inequality involves
only the states of the environment and the dynamical map of the open system
and, therefore, does not rely on the knowledge of either the microscopic
interaction Hamiltonian or the environmental Hamiltonian characteristic
parameters. We demonstrate the power of our result by applying it to two
different scenarios: quantum programming and quantum probing. In the first case
we use it to derive bounds on the dimension of the processor for approximate
programming of unitaries. In the second case we present an intriguing
proof-of-principle demonstration of the ability to extract information on the
environment via a quantum probe without any a priori assumption on the form of
the system-environment coupling Hamiltonian.


title:
Simultaneous Information and Energy Flow for IoT Relay Systems with
  Crowd Harvesting

abstract:
  It is expected that the number of wireless devices will grow rapidly over the
next few years due to the growing proliferation of Internet-of-Things (IoT). In
order to improve the energy efficiency of information transfer between small
devices, we review state-of-the-art research in simultaneous wireless energy
and information transfer, especially for relay based IoT systems. In
particular, we analyze simultaneous information-and-energy transfer from the
source node, and the design of time-switching and power-splitting operation
modes, as well as the associated optimization algorithms. We also investigate
the potential of crowd energy harvesting from transmission nodes that belong to
multiple radio networks. The combination of source and crowd energy harvesting
can greatly reduce the use of battery power and increase the availability and
reliability for relaying. We provide insight into the fundamental limits of
crowd energy harvesting reliability based on a case study using real city data.
Furthermore, we examine the optimization of transmissions in crowd harvesting,
especially with the use of node collaboration while guaranteeing
Quality-of-Service (QoS).


title:
Spin liquid and quantum phase transition without symmetry breaking in a
  frustrated three-dimensional Ising model

abstract:
  We show that the highly frustrated transverse-field Ising model on the
three-dimensional pyrochlore lattice realizes a first-order phase transition
without symmetry breaking between the low-field Coulomb quantum spin liquid and
the high-field polarized phase. The quantum phase transition is located
quantitively by comparing low- and high-field series expansions. Furthermore,
the intriguing properties of the elementary excitations in the polarized phase
are investigated. We argue that this model can be achieved experimentally by
applying mechanical strain to a classical spin ice material comprised of
non-Kramers spins such as Ho_2Ti_2O_7. Taken together with our results, this
provides a new experimental platform to study quantum spin liquid physics.


title:
A microscopic model for the magnetic field driven breakdown of the
  dissipationless state in the integer and fractional quantum Hall effect

abstract:
  Intra Landau level thermal activation, from localized states in the tail, to
delocalized states above the mobility edge in the same Landau level, explains
the $B_c(T)$ (half width of the dissipationless state) phase diagram for a
number of different quantum Hall samples with widely ranging carrier density,
mobility and disorder. Good agreement is achieved over $2-3$ orders of
magnitude in temperature and magnetic field for a wide range of filling
factors. The Landau level width is found to be independent of magnetic field.
The mobility edge moves, in the case of changing Landau level overlap to
maintain a sample dependent critical density of states at that energy. An
analysis of filling factor $\nu=2/3$ shows that the composite Fermion Landau
levels have exactly the same width as their electron counterparts. An important
ingredient of the model is the Lorentzian broadening with long tails which
provide localized states deep in the gap which are essential in order to
reproduce the robust high temperature $B_c(T)$ phase observed in experiment.


title:
Using a Szilard engine to illustrate the validity of the modified
  Jarzynski equality in presence of measurement errors

abstract:
  It has recently been shown that the Jarzynski equality gets modified, when
there are experimental errors in computing work. This modified result also
holds good in presence of feedback. In this work, we use a simple toy model,
that of a Szilard engine, to prove these results both in the presence and in
absence of feedback.


title:
New distances for a selected set of visual binaries with inconsistent
  dynamical masses

abstract:
  We have selected a set of 17 visual binaries that demonstrate great
inconsistency between the systemic mass obtained through Kepler's Third Law as
compared to that calculated through standard mass-luminosity and mass-spectrum
relationships. A careful inspection of orbital data and parallaxes showed that
the current orbits of nine binaries (WDS 00155-1608, WDS 00174+0853, WDS
05017+2050, WDS 06410+0954, WDS 16212-2536, WDS 17336-3706, WDS 19217-1557, WDS
20312+1116, and WDS 21118+5959) do not need to be improved, instead we
recommend different parallax (distance) value for them. On the other hand, we
considered that eight orbits (WDS 02366+1227, WDS 02434-6643, WDS 03244-1539,
WDS 08507+1800, WDS 09128-6055, WDS 11532-1540, WDS 17375+2419, and WDS
22408-0333) had to be improved. Due to various reasons mentioned in this paper,
their distances should most likely be corrected unless better orbital solutions
and/or more precise parallaxes are reported. To obtain consistent mass values,
the use of the dynamical parallax is still recommended for 5 out of the 8
improved orbits. For WDS 02434-6643, WDS 09128-6055, and WDS 11532-1540, the
improvement itself yields reasonable mass sums while maintaining {\pi}_{Hip}
within a 1-2{\sigma} margin. New distance estimates for 16 stars (mainly based
on the obtained dynamical parallaxes) and individual comments for all objects
are presented and discussed.


title: Singularities of Frontals

abstract:
  In this survey article we introduce the notion of frontals, which provides a
class of generalised submanifolds with singularities but with well-defined
tangent spaces. We present a review of basic theory and known studies on
frontals in several geometric problems from singularity theory viewpoints. In
particular, in this paper, we try to give some of detailed proofs and related
ideas, which were omitted in the original papers, to the basic and important
results related to frontals.


title: A deep learning model for estimating story points

abstract:
  Although there has been substantial research in software analytics for effort
estimation in traditional software projects, little work has been done for
estimation in agile projects, especially estimating user stories or issues.
Story points are the most common unit of measure used for estimating the effort
involved in implementing a user story or resolving an issue. In this paper, we
offer for the \emph{first} time a comprehensive dataset for story points-based
estimation that contains 23,313 issues from 16 open source projects. We also
propose a prediction model for estimating story points based on a novel
combination of two powerful deep learning architectures: long short-term memory
and recurrent highway network. Our prediction system is \emph{end-to-end}
trainable from raw input data to prediction outcomes without any manual feature
engineering. An empirical evaluation demonstrates that our approach
consistently outperforms three common effort estimation baselines and two
alternatives in both Mean Absolute Error and the Standardized Accuracy.


title: SU(2|2) supersymmetric mechanics

abstract:
  We introduce a new kind of non-relativistic ${\cal N}{=}\,8$ supersymmetric
mechanics, associated with worldline realizations of the supergroup $SU(2|2)$
treated as a deformation of flat ${\cal N}{=}\,8$, $d{=}1$ supersymmetry.
Various worldline $SU(2|2)$ superspaces are constructed as coset manifolds of
this supergroup, and the corresponding superfield techniques are developed. For
the off-shell $SU(2|2)$ multiplets $({\bf 3,8,5})$, $({\bf 4,8,4})$ and $({\bf
5,8,3})$, we construct and analyze the most general superfield and component
actions. Common features are mass oscillator-type terms proportional to the
deformation parameter and a trigonometric realization of the superconformal
group $OSp(4^*|4)$ in the conformal cases. For the simplest $({\bf 5, 8, 3})$
model the quantization is performed.


title: Mapping how local perturbations influence systems-level brain dynamics

abstract:
  The human brain exhibits a relatively stable spatiotemporal organization that
supports brain function and can be manipulated via local brain stimulation.
Such perturbations to local cortical dynamics are globally integrated by
distinct neural systems. However, it remains unclear how and why local changes
in neural activity affect large-scale system dynamics. Here, we briefly review
empirical and computational studies addressing how localized perturbations
affect brain activity. We then systematically analyze a model of large-scale
brain dynamics, assessing how localized changes in brain activity at the
different sites affect whole-brain dynamics. We find that local stimulation
induces changes in brain activity that can be summarized by relatively smooth
tuning curves, which relate a region's effectiveness as a stimulation site to
its position within the cortical hierarchy. Our results also support the notion
that brain hubs, operating in a slower regime, are more resilient to focal
perturbations and critically contribute to maintain stability in global brain
dynamics. In contrast, perturbations of peripheral regions, characterized by
faster activity, have greater impact on functional connectivity. As a parallel
with this region-level result, we also find that peripheral systems such as the
visual and sensorimotor networks were more affected by local perturbations than
high-level systems such as the cingulo-opercular network. Our results highlight
the importance of a periphery-to-core hierarchy to determine the effect of
local stimulation on the brain network. We also provide novel resources to
orient empirical work aiming at manipulating functional connectivity using
non-invasive brain stimulation.


title: Finite-temperature second-order many-body perturbation theory revisited

abstract:
  We present an algebraic, nondiagrammatic derivation of finite-temperature
second-order many-body perturbation theory [FT-MBPT(2)], using techniques and
concepts accessible to theoretical chemical physicists. We give explicit
expressions not just for the grand potential but particularly for the mean
energy of an interacting many-electron system. The framework presented is
suitable for computing the energy of a finite or infinite system in contact
with a heat and particle bath at finite temperature and chemical potential.
FT-MBPT(2) may be applied if the system, at zero temperature, may be described
using standard (i.e., zero-temperature) second-order many-body perturbation
theory [ZT-MBPT(2)] for the energy. We point out that in such a situation,
FT-MBPT(2) reproduces, in the zero-temperature limit, the energy computed
within ZT-MBPT(2). In other words, the difficulty that has been referred to as
the Kohn--Luttinger conundrum, does not occur. We comment, in this context, on
a "renormalization" scheme recently proposed by Hirata and He.


title:
AR Scorpii and possible gravitational wave radiation from pulsar white
  dwarfs

abstract:
  In view of the new recent observation and measurement of the rotating and
highly-magnetized white dwarf AR Scorpii \cite{Marsh:2016uhc}, we determine
bounds of its moment of inertia, magnetic fields and radius. Moreover, we
investigate the possibility of fast rotating and/or magnetized white dwarfs to
be source of detectable gravitational wave (GW) emission. Numerical stellar
models at different baryon masses are constructed. For each star configuration,
we compute self-consistent relativistic solutions for white dwarfs endowed with
poloidal magnetic fields by solving the Einstein-Maxwell field equations in a
self-consistent way. The magnetic field supplies an anisotropic pressure,
leading to the braking of the spherical symmetry of the star. In this case, we
compute the quadrupole moment of the mass distribution. Next, we perform an
estimate of the GW of such objects. Finally, we show that the new recent
observation and measurement pulsar white dwarf AR Scorpii, as well other
stellar models, are able to generate gravitational wave radiation that lies in
the bandwidth of the discussed next generation of space-based GW detectors
DECI-hertz interferometer Gravitational wave Observatory (DECIGO) and Big Bang
Observer (BBO).


title: Publication bias and the canonization of false facts

abstract:
  In the process of scientific inquiry, certain claims accumulate enough
support to be established as facts. Unfortunately, not every claim accorded the
status of fact turns out to be true. In this paper, we model the dynamic
process by which claims are canonized as fact through repeated experimental
confirmation. The community's confidence in a claim constitutes a Markov
process: each successive published result shifts the degree of belief, until
sufficient evidence accumulates to accept the claim as fact or to reject it as
false. In our model, publication bias --- in which positive results are
published preferentially over negative ones --- influences the distribution of
published results. We find that when readers do not know the degree of
publication bias and thus cannot condition on it, false claims often can be
canonized as facts. Unless a sufficient fraction of negative results are
published, the scientific process will do a poor job at discriminating false
from true claims. This problem is exacerbated when scientists engage in
p-hacking, data dredging, and other behaviors that increase the rate at which
false positives are published. If negative results become easier to publish as
a claim approaches acceptance as a fact, however, true and false claims can be
more readily distinguished. To the degree that the model accurately represents
current scholarly practice, there will be serious concern about the validity of
purported facts in some areas of scientific research.


title:
An constructive proof for the Umemura polynomials for the third
  Painlev\'e equation

abstract:
  We are concerned with the Umemura polynomials associated with the third
Painlev\'e equation. We extend Taneda's method, which was developed for the
Yablonskii--Vorob'ev polynomials associated with the second Painlev\'e
equation, to give an algebraic proof that the rational functions generated by
the nonlinear recurrence relation satisfied by Umemura polynomials are indeed
polynomials. Our proof is constructive and gives information about the roots of
the Umemura polynomials.


title:
Label distribution based facial attractiveness computation by deep
  residual learning

abstract:
  Two challenges lie in the facial attractiveness computation research: the
lack of true attractiveness labels (scores), and the lack of an accurate face
representation. In order to address the first challenge, this paper recasts
facial attractiveness computation as a label distribution learning (LDL)
problem rather than a traditional single-label supervised learning task. In
this way, the negative influence of the label incomplete problem can be
reduced. Inspired by the recent promising work in face recognition using deep
neural networks to learn effective features, the second challenge is expected
to be solved from a deep learning point of view. A very deep residual network
is utilized to enable automatic learning of hierarchical aesthetics
representation. Integrating these two ideas, an end-to-end deep learning
framework is established. Our approach achieves the best results on a standard
benchmark SCUT-FBP dataset compared with other state-of-the-art work.


title: EELT-HIRES the high-resolution spectrograph for the E-ELT

abstract:
  The first generation of E-ELT instruments will include an optical-infrared
High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which
will be capable of providing unique breakthroughs in the fields of exoplanets,
star and planet formation, physics and evolution of stars and galaxies,
cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES
has just started and will be performed by a consortium composed of institutes
and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland,
Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we
describe the science goals and the preliminary technical concept for EELT-HIRES
which will be developed during the phase A, as well as its planned development
and consortium organisation during the study.


title:
Simple determinantal representations of up to quintic bivariate
  polynomials

abstract:
  For bivariate polynomials of degree $n\le 5$ we give fast numerical
constructions of determinantal representations with $n\times n$ matrices.
Unlike some other available constructions, our approach returns matrices of the
smallest possible size $n\times n$ for all polynomials of degree $n$ and does
not require any symbolic computation. We can apply these linearizations to
numerically compute the roots of a system of two bivariate polynomials by using
numerical methods for two-parameter eigenvalue problems.


title: The faint radio sky: radio astronomy becomes mainstream

abstract:
  Radio astronomy has changed. For years it studied relatively rare sources,
which emit mostly non-thermal radiation across the entire electromagnetic
spectrum, i.e. radio quasars and radio galaxies. Now it is reaching such faint
flux densities that it detects mainly star-forming galaxies and the more common
radio-quiet active galactic nuclei. These sources make up the bulk of the
extragalactic sky, which has been studied for decades in the infrared, optical,
and X-ray bands. I follow the transformation of radio astronomy by reviewing
the main components of the radio sky at the bright and faint ends, the issue of
their proper classification, their number counts, luminosity functions, and
evolution. The overall "big picture" astrophysical implications of these
results, and their relevance for a number of hot topics in extragalactic
astronomy, are also discussed. The future prospects of the faint radio sky are
very bright, as we will soon be flooded with survey data. This review should be
useful to all extragalactic astronomers, irrespective of their favourite
electromagnetic band(s), and even stellar astronomers might find it somewhat
gratifying.


title:
Predictability of the Appearance of Anomalous Waves at Sufficiently
  Small Benjamin-Feir Indices

abstract:
  The numerical simulation of the nonlinear dynamics of random sea waves at
moderately small Benjamin-Feir indices and its comparison with the linear
dynamics (at the coincidence of spatial Fourier harmonics near a spectral peak
at a certain time $t_p$) indicate that the appearance of a rogue wave can be
predicted in advance. If the linear approximation shows the presence of a
sufficiently extensive and/or high group of waves in the near future after
$t_p$, an anomalous wave is almost necessarily formed in the nonlinear model.
The interval of reliable forecasting covers several hundred wave periods, which
can be quite sufficient in practice for, e.g., avoiding the meeting of a ship
with a giant wave.


title: Failed Growth at the Bouncing Barrier in Planetesimal Formation

abstract:
  In laboratory experiments, we studied collisions of ensembles of compact
(filling factor 0.33) millimeter dust aggregates composed of micrometer quartz
grains. We used cylindrical aggregates, triangular aggregates, square
aggregates, and rectangular aggregates. Ensembles of equal size aggregates as
well as ensembles with embedded larger aggregates were studied. The typical
collision velocities are 10-20 mm $\rm s^{-1}$. High spatial and temporal
resolution imaging unambiguously shows that individual collisions lead to
sticking with a high probability of 20 percent. This leads to connected
clusters of aggregates. The contact areas between two aggregates increase with
collision velocity. However, this cluster growth is only temporary, as
subsequent collisions of aggregates and clusters eventually lead to the
detachment of all aggregates from a cluster. The contacts are very fragile as
aggregates cannot be compressed further or fragment under our experimental
conditions to enhance the contact stability. Therefore, the evolution of the
ensemble always leads back to a distribution of individual aggregates of
initial size. This supports and extends earlier experiments showing that a
bouncing barrier in planetesimal formation would be robust against shape and
size variations.


title:
Top quark event modelling and generators in the CMS experiment at the
  LHC

abstract:
  State-of-the-art theoretical predictions accurate to next-to-leading order
QCD interfaced with {\sc pythia} and {\sc herwig} are tested by comparing the
unfolded $t\bar{t}$ differential data collected with the CMS detector at 8 TeV
and 13 TeV. These predictions are also compared with the measurements of
underlying event activity distributions accompanying ${\rm t\bar{t}}$ events.
Furthermore, predictions of beyond NLO accuracy in QCD are compared with the
data.


title:
Rational solutions of the Boussinesq equation and applications to rogue
  waves

abstract:
  We study rational solutions of the Boussinesq equation, which is a soliton
equation solvable by the inverse scattering method. These rational solutions,
which are algebraically decaying and depend on two arbitrary parameters, are
expressed in terms of special polynomials that are derived through a bilinear
equation, have a similar appearance to rogue-wave solutions of the focusing
nonlinear Schr\"odinger (NLS) equation and have an interesting structure.
Further rational solutions of the Kadomtsev-Petviashvili I (KPI) equation are
derived in two ways, from rational solutions of the NLS equation and from
rational solutions of the Boussinesq equation. It is shown that the two
families of rational solutions of the KPI equation are fundamentally different.


title:
Quantifying lost information due to covariance matrix estimation in
  parameter inference

abstract:
  Parameter inference with an estimated covariance matrix systematically loses
information due to the remaining uncertainty of the covariance matrix. Here, we
quantify this loss of precision and develop a framework to hypothetically
restore it, which allows to judge how far away a given analysis is from the
ideal case of a known covariance matrix. We point out that it is insufficient
to estimate this loss by debiasing a Fisher matrix as previously done, due to a
fundamental inequality that describes how biases arise in non-linear functions.
We therefore develop direct estimators for parameter credibility contours and
the figure of merit. We apply our results to DES Science Verification weak
lensing data, detecting a 10% loss of information that increases their
credibility contours. No significant loss of information is found for KiDS. For
a Euclid-like survey, with about 10 nuisance parameters we find that 2900
simulations are sufficient to limit the systematically lost information to 1%,
with an additional uncertainty of about 2%. Without any nuisance parameters
1900 simulations are sufficient to only lose 1% of information. We also derive
an estimator for the Fisher matrix of the unknown true covariance matrix, two
estimators of its inverse with different physical meanings, and an estimator
for the optimally achievable figure of merit. The formalism here quantifies the
gains to be made by running more simulated datasets, allowing decisions to be
made about numbers of simulations in an informed way.


title: Topology of scrambled simplices

abstract:
  In this paper we define a family of topological spaces, which contains and
vastly generalizes the higher-dimensional Dunce hats. Our definition is purely
combinatorial, and is phrased in terms of identifications of boundary simplices
of a~standard d-simplex. By virtue of the construction, the obtained spaces may
be indexed by words, and they automatically carry the structure of a
$\Delta$-complex.
  As our main result, we completely determine the homotopy type of these
spaces. In fact, somewhat surprisingly, we are able to prove that each of them
is either contractible or homotopy equivalent to an odd-dimensional sphere. We
develop the language to determine the homotopy type directly from the
combinatorics of the indexing word.
  As added benefit of our investigation, we are able to emulate the Dunce hat
phenomenon, and to obtain a large family of both $\Delta$-complexes, as well as
simplicial complexes, which are contractible, but not collapsible.


title: Some Statistics concerning the Austrian Presidential Election 2016

abstract:
  The 2016 Austrian presidential runoff election has been repealed by the
Austrian constitutional court. The results of the counted votes had yielded a
victory of Alexander van der Bellen by a margin of 30.863 votes as compared to
the votes for Norbert Hofer. However, the constitutional court found that
77.769 votes were "contaminated" as there have been -- at least on a formal
level - violations of the legal procedure when counting those votes. For
example, the envelopes were opened prematurely, or not all the members of the
electoral board were present during the counting etc. Hence the court
considered the scenario that the irregular counting of these votes might have
caused a reversal of the result as possible. The constitutional court sentenced
that this possibility presents a sufficient irregularity in order to order a
repetition of the entire election. While it is, of course, possible that the
irregular counting of those 77.769 votes reversed the result, we shall show
that the probability, that this indeed has happened, is ridiculously low.


title:
The 3rd Reactive Synthesis Competition (SYNTCOMP 2016): Benchmarks,
  Participants & Results

abstract:
  We report on the benchmarks, participants and results of the third reactive
synthesis competition(SYNTCOMP 2016). The benchmark library of SYNTCOMP 2016
has been extended to benchmarks in the new LTL-based temporal logic synthesis
format (TLSF), and 2 new sets of benchmarks for the existing AIGER-based format
for safety specifications. The participants of SYNTCOMP 2016 can be separated
according to these two classes of specifications, and we give an overview of
the 6 tools that entered the competition in the AIGER-based track, and the 3
participants that entered the TLSF-based track. We briefly describe the
benchmark selection, evaluation scheme and the experimental setup of SYNTCOMP
2016. Finally, we present and analyze the results of our experimental
evaluation, including a comparison to participants of previous competitions and
a legacy tool.


title:
The solar chromosphere as induction disk and the inverse Joule-Thomson
  effect

abstract:
  The connection between nuclear fusion in the Sun's core and solar irradiance
is obscured among other things by uncertainty over the mechanism of coronal
heating. Data for solar wind density and velocity, sunspot number, and EUV flux
suggest that electromagnetic energy from the Sun's convection zone is converted
by induction through the chromosphere into thermal energy. The helium and
hydrogen mixture exhaled by the Sun is then heated by the inverse Joule-Thomson
effect when it expands via the corona into space. The almost complete shutdown
of the solar wind on 10-11 May 1999 demonstrated that its velocity is a more
faithful indicator of solar activity than are sunspots as it reflects
short-term variations in coronal heating rather than quasicyclical fluctuations
in the Sun's magnetism. Its reconstruction from the cosmic ray flux using
isotopes spanning over 800,000 yr should therefore benefit the analysis and
long-term forecasting of Earth and space weather.


title: An arithmetic Bern\v{s}tein-Ku\v{s}nirenko inequality

abstract:
  We present an upper bound for the height of the isolated zeros in the torus
of a system of Laurent polynomials over an adelic field satisfying the product
formula. This upper bound is expressed in terms of the mixed integrals of the
local roof functions associated to the chosen height function and to the system
of Laurent polynomials. We also show that this bound is close to optimal in
some families of examples. This result is an arithmetic analogue of the
classical Bern\v{s}tein-Ku\v{s}nirenko theorem. Its proof is based on
arithmetic intersection theory on toric varieties.


title: Local Decoders for the 2D and 4D Toric Code

abstract:
  We analyze the performance of decoders for the 2D and 4D toric code which are
local by construction. The 2D decoder is a cellular automaton decoder
formulated by Harrington which explicitly has a finite speed of communication
and computation. For a model of independent $X$ and $Z$ errors and faulty
syndrome measurements with identical probability we report a threshold of
$0.133\%$ for this Harrington decoder. We implement a decoder for the 4D toric
code which is based on a decoder by Hastings arXiv:1312.2546 . Incorporating a
method for handling faulty syndromes we estimate a threshold of $1.59\%$ for
the same noise model as in the 2D case. We compare the performance of this
decoder with a decoder based on a 4D version of Toom's cellular automaton rule
as well as the decoding method suggested by Dennis et al.
arXiv:quant-ph/0110143 .


title: Generalized Group Profiling for Content Customization

abstract:
  There is an ongoing debate on personalization, adapting results to the unique
user exploiting a user's personal history, versus customization, adapting
results to a group profile sharing one or more characteristics with the user at
hand. Personal profiles are often sparse, due to cold start problems and the
fact that users typically search for new items or information, necessitating to
back-off to customization, but group profiles often suffer from accidental
features brought in by the unique individual contributing to the group. In this
paper we propose a generalized group profiling approach that teases apart the
exact contribution of the individual user level and the "abstract" group level
by extracting a latent model that captures all, and only, the essential
features of the whole group. Our main findings are the followings. First, we
propose an efficient way of group profiling which implicitly eliminates the
general and specific features from users' models in a group and takes out the
abstract model representing the whole group. Second, we employ the resulting
models in the task of contextual suggestion. We analyse different grouping
criteria and we find that group-based suggestions improve the customization.
Third, we see that the granularity of groups affects the quality of group
profiling. We observe that grouping approach should compromise between the
level of customization and groups' size.


title: Beyond Highway Dimension: Small Distance Labels Using Tree Skeletons

abstract:
  The goal of a hub-based distance labeling scheme for a network G = (V, E) is
to assign a small subset S(u) $\subseteq$ V to each node u $\in$ V, in such a
way that for any pair of nodes u, v, the intersection of hub sets S(u) $\cap$
S(v) contains a node on the shortest uv-path. The existence of small hub sets,
and consequently efficient shortest path processing algorithms, for road
networks is an empirical observation. A theoretical explanation for this
phenomenon was proposed by Abraham et al. (SODA 2010) through a network
parameter they called highway dimension, which captures the size of a hitting
set for a collection of shortest paths of length at least r intersecting a
given ball of radius 2r. In this work, we revisit this explanation, introducing
a more tractable (and directly comparable) parameter based solely on the
structure of shortest-path spanning trees, which we call skeleton dimension. We
show that skeleton dimension admits an intuitive definition for both directed
and undirected graphs, provides a way of computing labels more efficiently than
by using highway dimension, and leads to comparable or stronger theoretical
bounds on hub set size.


title: Possible explanations for fine-tuning of the universe

abstract:
  The Froggatt-Nielsen mechanism and the multi-local field theory are
interesting and promising candidates for solving the naturalness problem in the
universe. These theories are based on the different physical principles: The
former assumes the micro-canonical partition function $\int {\cal{D}}\phi\
\prod_i \delta (S_i^{}-I_i^{})$, and the latter assumes the partition function
$\int {\cal{D}}\phi\ \exp\left(iS_M^{}\right)$ where $S_M^{}$ is the
multi-local action $\sum_i c_i^{}S_i^{}+\sum_{i,j}c_{i,j}^{}S_i^{}S_j^{}+\cdots
$. Our main purpose is to show that they are equivalent in the sense that they
predict the same fine-tuning mechanism. In order to clarify our argument, we
first study (review) the similarity between the Froggatt-Nielsen mechanism and
statistical mechanics in detail, and show that the dynamical fine-tuning in the
former picture can be understood completely in the same way as the
determination of the temperature in the latter picture. Afterward, we discuss
the multi-local theory and the equivalence between it and the the
Froggatt-Nielsen mechanism. Because the multi-local field theory can be
obtained from physics at the Planck/String scale, this equivalence indicates
that the micro-canonical picture can also originate in such physics. As a
concrete example, we also review the IIB matrix model as an origin of the
multi-local theory.


title:
On Horizontal and Vertical Separation in Hierarchical Text
  Classification

abstract:
  Hierarchy is a common and effective way of organizing data and representing
their relationships at different levels of abstraction. However, hierarchical
data dependencies cause difficulties in the estimation of "separable" models
that can distinguish between the entities in the hierarchy. Extracting
separable models of hierarchical entities requires us to take their relative
position into account and to consider the different types of dependencies in
the hierarchy. In this paper, we present an investigation of the effect of
separability in text-based entity classification and argue that in hierarchical
classification, a separation property should be established between entities
not only in the same layer, but also in different layers. Our main findings are
the followings. First, we analyse the importance of separability on the data
representation in the task of classification and based on that, we introduce a
"Strong Separation Principle" for optimizing expected effectiveness of
classifiers decision based on separation property. Second, we present
Hierarchical Significant Words Language Models (HSWLM) which capture all, and
only, the essential features of hierarchical entities according to their
relative position in the hierarchy resulting in horizontally and vertically
separable models. Third, we validate our claims on real-world data and
demonstrate that how HSWLM improves the accuracy of classification and how it
provides transferable models over time. Although discussions in this paper
focus on the classification problem, the models are applicable to any
information access tasks on data that has, or can be mapped to, a hierarchical
structure.


title: Enumerating independent vertex sets in grid graphs

abstract:
  A set of vertices in a graph is called independent if no two vertices of the
set are connected by an edge. In this paper we use the state matrix recursion
algorithm, developed by Oh, to enumerate independent vertex sets in a grid
graph and even further to provide the generating function with respect to the
number of vertices. We also enumerate bipartite independent vertex sets in a
grid graph. The asymptotic behavior of their growth rates is presented.


title: The complexity of a flat groupoid

abstract:
  Grothendieck proved that any finite epimorphism of noetherian schemes factors
into a finite sequence of effective epimorphisms. We define the complexity of a
flat groupoid $R\rightrightarrows X$ with finite stabilizer to be the length of
the canonical sequence of the finite map $R\to X\times\_{X/R} X$, where $X/R$
is the Keel-Mori geometric quotient. For groupoids of complexity at most 1, we
prove a theorem of descent along the quotient $X\to X/R$ and a theorem of
quotient of a groupoid by a normal subgroupoid. We expect that the complexity
could play an important role in the finer study of quotients by groupoids.


title: Quantum knot mosaics and the growth constant

abstract:
  Lomonaco and Kauffman introduced a knot mosaic system to give a precise and
workable definition of a quantum knot system, the states of which are called
quantum knots. This paper is inspired by an open question about the knot mosaic
enumeration suggested by them. A knot $n$--mosaic is an $n \times n$ array of
11 mosaic tiles representing a knot or a link diagram by adjoining properly
that is called suitably connected. The total number of knot $n$--mosaics is
denoted by $D_n$ which is known to grow in a quadratic exponential rate. In
this paper, we show the existence of the knot mosaic constant $\delta = \lim_{n
\rightarrow \infty} D_n^{\ \frac{1}{n^2}}$ and prove that $$4 \leq \delta \leq
\frac{5+ \sqrt{13}}{2} \ (\approx 4.303).$$


title:
On orders of elements of finite almost simple groups with linear or
  unitary socle

abstract:
  We say that a finite almost simple $G$ with socle $S$ is admissible (with
respect to the spectrum) if $G$ and $S$ have the same sets of orders of
elements. Let $L$ be a finite simple linear or unitary group of dimension at
least three over a field of odd characteristic. We describe admissible almost
simple groups with socle $L$. Also we calculate the orders of elements of the
coset $L\tau$, where $\tau$ is the inverse-transpose automorphism of $L$.


title:
A simple phase-field approximation of the Steiner problem in dimension
  two

abstract:
  In this paper we consider the branched transportation problem in 2D
associated with a cost per unit length of the form $1 + \alpha m$ where $m$
denotes the amount of transported mass and $\alpha > 0$ is a fixed parameter
(notice that the limit case $\alpha = 0$ corresponds to the classical Steiner
problem). Motivated by the numerical approximation of this problem, we
introduce a family of functionals $(\{F_\epsilon\}_{\epsilon>0})$ which
approximate the above branched transport energy. We justify rigorously the
approximation by establishing the equicoercivity and the $\Gamma$-convergence
of $\{F_\epsilon\}$ as $\epsilon \downarrow 0$. Our functionals are modeled on
the Ambrosio-Tortorelli functional and are easy to optimize in practice. We
present numerical evidences of the efficiency of the method.


title: Species coexistence in a neutral dynamics with environmental noise

abstract:
  Environmental fluctuations have important consequences in the organization of
ecological communities, and understanding how such a variability influences the
biodiversity of an ecosystem is a major question in ecology. In this paper, we
analyze the case of two species competing for the resources within the
framework of the neutral theory in the presence of environmental noise,
devoting special attention on how such a variability modulates species fitness.
The environment is dichotomous and stochastically alternates between periods
favoring one of the species while disfavoring the other one, preserving
neutrality on the long term. We study two different scenarios: in the first one
species fitness varies linearly with the environment, and in the second one the
effective fitness is re-scaled by the total fitness of the individuals
competing for the same resource. We find that, in the former case environmental
fluctuations always reduce the time of species coexistence, whereas such a time
can be enhanced or reduced in the latter case, depending on the correlation
time of the environment. This phenomenon can be understood as a direct
consequence of Chesson's storage effect.


title:
High-quality photonic entanglement for wavelength-multiplexed quantum
  communication based on a silicon chip

abstract:
  We report an efficient energy-time entangled photon-pair source based on
four-wave mixing in a CMOS-compatible silicon photonics ring resonator. Thanks
to suitable optimization, the source shows a large spectral brightness of
400\,pairs of entangled photons /s/MHz for $\rm 500\,\mu W$ pump power.
Additionally, the resonator has been engineered so as to generate a frequency
comb structure compatible with standard telecom dense wavelength division
multiplexers. We demonstrate high-purity energy-time entanglement, i.e., free
of photonic noise, with near perfect raw visibilities ($>$~98\%) between
various channel pairs in the telecom C-band. Such a compact source stands as a
path towards more complex quantum photonic circuits dedicated to quantum
communication systems.


title:
Espaces de configuration g\'en\'eralis\'es. Espaces topologiques
  $i$-acycliques. Suites spectrales "basiques"

abstract:
  The generalized (ordered) configuration spaces associated to a topological
space $X$ are the spaces $\Delta_{\leq\ell}X^{m}:=\{(x_1,\ldots,x_{m})\in
X^{m}\mid\#\{x_1,\ldots,x_{m}\}\leq \ell\}$ and
$\Delta_{\ell}X^{m}:=\Delta_{\leq\ell}X^{m}\setminus \Delta_{\leq\ell-1}$. They
are equipped with the action of the symmetric group $S_m$ permuting
coordinates. When $X$ has no interior cohomology (i.e. is $i$-acyclic) we are
able to compute explicitly the character formula of $S_m$ acting on the
cohomology of these spaces, and if $X$ is furthermore a connected and oriented
pseudomanifold of dimension $\geq2$ we generalize Church's representation
stability theorem to the case of the families $\{\Delta_{\leq m-a}X^m\}_m$ and
$\{\Delta_{\ell-a}X^m\}_m$. We show that, for fixed $a,i\in\mathbb N$, the
families of representations $\{ S_m: H ^{i}(\Delta_{?m-a}X^{m})\}_{m}$ are
monotone and stationary for $m\geq4i+4a$, if $d_{X}=2$, and for $m\geq2i+4a$,
if $d_{X}\geq3$. The corresponding families of characters and Betti numbers are
(hence) polynomial and the families of integers $\{\mathop{\rm
Betti}_{i}({\Delta_{?m-a}X^{m} / S_m})\}_{m}$ are constant within the same
range of integers $m$. We further show that the family $\{\mathop{\rm
Betti}_{i}({\Delta_{m}X^{m}/ S_m})\}_{m}$ is constant for $m\geq 2i$, if
$d_{X}=2$, and for $m\geq i$, if $d_{X}\geq3$. In particular, complex algebraic
varieties whether they are smooth on not verify these generalizations of
Church's stability theorems.


title: Euclidean 1-center of a set of static and mobile points

abstract:
  In this paper, we consider the problem of computing the algebraic parametric
equation of the Euclidean 1-center function in $\mathbb{R}^d$, $d \geq 2$, for
a system of $n$ static points and $m$ mobile points having motion defined by
rational parametric functions. We have shown that the corresponding Euclidean
1-center function is a piecewise differentiable function and have derived its
exact parametric algebraic equation. If the positions of the static points and
the rational parametric equations of the motion of the mobile points are given,
we have proposed an algorithm that computes the parametric equation of the
Euclidean 1-center function.


title:
Optical linear polarization of 74 white dwarfs with the RoboPol
  polarimeter

abstract:
  We present the first linear polarimetric survey of white dwarfs (WDs). Our
sample consists of WDs of DA and DC spectral types in the SDSS r magnitude
range from 13 to 17. We performed polarimetric observations with the RoboPol
polarimeter attached to the 1.3-m telescope at the Skinakas Observatory. We
have 74 WDs in our sample, of which almost all are low polarized WDs with
polarization degree (PD) smaller than 1%, while only 2 have PD higher than 1%.
There is an evidence that on average the isolated WDs of DC type have higher PD
(with median PD of 0.78%) than the isolated DA type WDs (with median PD of
0.36%). On the other hand, the median PD of isolated DA type WDs is almost the
same, i.e. 0.36% as the median PD of DA type white dwarfs in binary systems
with red dwarfs (dM type), i.e. 0.33%. This shows, as expected, that there is
no contribution to the PD from the companion if the WD companion is the red
dwarf, which is the most common situation for WDs binary systems. We do not
find differences in the polarization degree between magnetic and non-magnetic
WDs. Because 97% of WDs in our sample have PD lower than 1%, they can be used
as faint zero--polarized standard star in the magnitude range from 13 up to 17
of SDSS r filter. They cover the Northern sky between 13 hour to 23 hour in
right ascension and from -11 degrees to 78 degrees in declination.
Additionally, we found that for low extinction values (< 0.04) the best model
that describes the dependence of PD on E(B-V) is given by the equation:
PD_{max, ISM}[%] = 0.65 x E(B-V)^{0.12}.


title: Effective equidistribution of rational points on expanding horospheres

abstract:
  Einsiedler, Mozes, Shah and Shapira [Compos. Math. 152 (2016), 667-692] prove
an equidistribution theorem for rational points on expanding horospheres in the
space of d-dimensional Euclidean lattices, with d>2. Their proof exploits
measure classification results, but provides no insight into the rate of
convergence. We pursue here an alternative approach, based on harmonic analysis
and Weil's bound for Kloosterman sums, which in dimension d=3 yields an
effective estimate on the rate of convergence.


title: High degree of current rectification at nanoscale level

abstract:
  We address an unexpectedly large rectification using a simple quantum wire
with correlated site potentials. The external electric field, associated with
voltage bias, leads to unequal charge currents for two different polarities of
external bias and this effect is further enhanced by incorporating the
asymmetry in wire-to-electrode coupling. Our calculations suggest that in some
cases almost cent percent rectification is obtained for a wide bias window.
This performance is valid against disorder configurations and thus we can
expect an experimental verification of our theoretical analysis in near future.


title:
Path-dependent initialization of a single quantum dot exciton spin in a
  nano-photonic waveguide

abstract:
  We demonstrate a scheme for in-plane initialization and readout of a single
exciton spin in an InGaAs quantum dot (QD) coupled to a GaAs nanobeam
waveguide. The chiral coupling of the QD and the optical mode of the nanobeam
enables spin initialization and readout fidelity approaching unity in magnetic
field $B=1$ T and $\sim$0.9 without the field. We further show that this
in-plane excitation scheme is independent of the incident excitation laser
polarization and depends solely on the excitation direction. This scheme
provides a robust in-plane spin excitation basis for a photon-mediated spin
network for quantum information applications.


title:
Fast neutrino flavor conversions near the supernova core with realistic
  flavor-dependent angular distributions

abstract:
  It has been recently pointed out that neutrino fluxes from a supernova can
show substantial flavor conversions almost immediately above the core. Using
linear stability analyses and numerical solutions of the fully nonlinear
equations of motion, we perform a detailed study of these fast conversions,
focussing on the region just above the supernova core. We carefully specify the
instabilities for evolution in space or time, andfind that neutrinos travelling
towards the core make fast conversions more generic, i.e., possible for a wider
range of flux ratios and angular asymmetries that produce a crossing between
the zenith-angle spectra of $\nu_e$ and ${\bar\nu_e}$. Using fluxes and angular
distributions predicted by supernova simulations, we find that fast conversions
can occur within tens of nanoseconds, only a few meters away from the putative
neutrinospheres. If these fast flavor conversions indeed take place, they would
have important implications for the supernova explosion mechanism and
nucleosynthesis.


title: Chemoselective Reactivity of Bifunctional Cyclooctynes on Si(001)

abstract:
  Controlled organic functionalization of silicon surfaces as integral part of
semiconductor technology offers new perspectives for a wide range of
applications. The high reactivity of the silicon dangling bonds, however,
presents a major hindrance for the first basic reaction step of such a
functionalization, i.e., the chemoselective attachment of bifunctional organic
molecules on the pristine silicon surface. We overcome this problem by
employing cyclooctyne as the major building block of our strategy.
Functionalized cyclooctynes are shown to react on Si(001) selectively via the
strained cyclooctyne triple bond while leaving the side groups intact. The
achieved selectivity originates from the distinctly different adsorption
dynamics of the separate functionalities: A direct adsorption pathway is
demonstrated for cyclooctyne as opposed to the vast majority of other organic
functional groups. The latter ones react on Si(001) via a metastable
intermediate which makes them effectively unreactive in competition with the
direct pathway of cyclooctyne's strained triple bond.


title: Short Proof of Erd\H os Conjecture for Triple Systems

abstract:
  In 1965 Erd\H os conjectured that for all $k\ge2$, $s\ge1$ and $n\ge k(s+1)$,
an $n$-vertex $k$-uniform hypergraph $\F$ with $\nu(\F)=s$ cannot have more
than \newline $\max\{\binom{sk+k-1}k,\;\binom nk-\binom{n-s}k\}$ edges. It took
almost fifty years to prove it for triple systems. In 2012 we proved the
conjecture for all $s$ and all $n\ge4(s+1)$. Then {\L}uczak and Mieczkowska
(2013) proved the conjecture for sufficiently large $s$ and all $n$. Soon
after, Frankl proved it for all $s$. Here we present a simpler version of that
proof which yields Erd\H os's conjecture for $s\ge33$. Our motivation is to lay
down foundations for a possible proof in the much harder case $k=4$, at least
for large $s$.


title: The weakest nontrivial idempotent equations

abstract:
  An equational condition is a set of equations in an algebraic language, and
an algebraic structure satisfies such a condition if it possesses terms that
meet the required equations. We find a single nontrivial equational condition
which is implied by any nontrivial idempotent equational condition.


title: Can background cosmology hold the key for modified gravity tests?

abstract:
  Modified gravity theories are a popular alternative to dark energy as a
possible explanation for the observed accelerating cosmic expansion, and their
cosmological tests are currently an active research field. Studies in recent
years have been increasingly focused on testing these theories in the nonlinear
regime, which is computationally demanding. Here we show that, under certain
circumstances, a whole class of theories can be ruled out by using background
cosmology alone. This is possible because certain classes of models (i) are
fundamentally incapable of producing specific background expansion histories,
and (ii) said histories are incompatible with local gravity tests. As an
example, we demonstrate that a popular class of models, $f(R)$ gravity, would
not be viable if observations suggest even a slight deviation of the background
expansion history from that of the $\Lambda$CDM paradigm.


title: Large deviation inequalities for sums of indicator variables

abstract:
  A survey is given of some Chernoff type bounds for the tail probabilities
P(X-EX > a) and P(X-EX < a) when X is a random variable that can be written as
a sum of indicator variables that are either independent or negatively related.
Most bounds are previously known and some comparisons are made.
  This paper was written in 1994, but was never published because I had
overlooked some existing papers containing some of the inequalities. Because of
some recent interest in one of the inequalities, which does not seem to be
published anywhere else, it has now been lightly edited and made available
here.


title: K2P$^2$: Reduced data from campaigns 0-4 of the K2 mission

abstract:
  Context: After the loss of a second reaction wheel the Kepler mission was
redesigned as the K2 mission, pointing towards the ecliptic and delivering data
for new fields approximately every 80 days. The steady flow of data obtained
with a reduced pointing stability calls for dedicated pipelines for extracting
light curves and correcting these for use in, e.g., asteroseismic analysis.
Aims: We provide corrected light curves for the K2 fields observed until now
(campaigns 0-4), and provide a comparison with other pipelines for K2 data
extraction/correction. Methods: Raw light curves are extracted from K2 pixel
data using the "K2-pixel-photometry" (K2P$^2$) pipeline, and corrected using
the KASOC filter. Results: The use of K2P$^2$ allows for the extraction of the
order of 90.000 targets in addition to 70.000 targets proposed by the community
- for these, other pipelines provide no data. We find that K2P$^2$ in general
performs as well as, or better than, other pipelines for the tested metrics of
photometric quality. In addition to stars, pixel masks are properly defined
using K2P$^2$ for extended objects such as galaxies for which light curves are
also extracted.


title:
Radial velocity observations of the 2015 Mar 20 eclipse - A benchmark
  Rossiter-McLaughlin curve with zero free parameters

abstract:
  On March 20, 2015, we obtained 159 spectra of the Sun as a star with the
solar telescope and the FTS at the Institut f\"ur Astrophysik G\"ottingen, 76
spectra were taken during partial solar eclipse. We obtained RVs using $I_2$ as
wavelength reference and determined the RM curve with a peak-to-peak amplitude
of almost 1.4 km s$^{-1}$ at typical RV precision better than 1 m s$^{-1}$. We
modeled disk-integrated solar RVs using surface velocities, limb darkening, and
information about convective blueshift from 3D magneto-hydrodynamic
simulations. We confirm that convective blueshift is crucial to understand
solar RVs during eclipse. Our best model reproduced the observations to within
a relative precision of 10% with residuals less than 30 m s$^{-1}$. We
cross-checked parameterizations of velocity fields using a Dopplergram from the
Solar Dynamics Observatory and conclude that disk-integration of the
Dopplergram does not provide correct information about convective blueshift
necessary for m s$^{-1}$ RV work. As main limitation for modeling RVs during
eclipses, we identified limited knowledge about convective blueshift and line
shape as functions of solar limb angle. We suspect that our model line profiles
are too shallow at limb angles larger than $\mu = 0.6$ resulting in incorrect
weighting of the velocities across the solar disk. Alternative explanations
cannot be excluded like suppression of convection in magnetic areas and
undiscovered systematics during eclipse observations. Accurate observations of
solar line profiles across the solar disk are suggested. We publish our RVs
taken during solar eclipse as a benchmark curve for codes calculating the RM
effect and for models of solar surface velocities and line profiles.


title:
A Machine Learning Analysis of Twitter Sentiment to the Sandy Hook
  Shootings

abstract:
  Gun related violence is a complex issue and accounts for a large proportion
of violent incidents. In the research reported in this paper, we set out to
investigate the pro-gun and anti-gun sentiments expressed on a social media
platform, namely Twitter, in response to the 2012 Sandy Hook Elementary School
shooting in Connecticut, USA. Machine learning techniques are applied to
classify a data corpus of over 700,000 tweets. The sentiments are captured
using a public sentiment score that considers the volume of tweets as well as
population. A web-based interactive tool is developed to visualise the
sentiments and is available at http://www.gunsontwitter.com. The key findings
from this research are: (i) There are elevated rates of both pro-gun and
anti-gun sentiments on the day of the shooting. Surprisingly, the pro-gun
sentiment remains high for a number of days following the event but the
anti-gun sentiment quickly falls to pre-event levels. (ii) There is a different
public response from each state, with the highest pro-gun sentiment not coming
from those with highest gun ownership levels but rather from California, Texas
and New York.


title:
The Lockman Hole project: LOFAR observations and spectral index
  properties of low-frequency radio sources

abstract:
  The Lockman Hole is a well-studied extragalactic field with extensive
multi-band ancillary data covering a wide range in frequency, essential for
characterising the physical and evolutionary properties of the various source
populations detected in deep radio fields (mainly star-forming galaxies and
AGNs). In this paper we present new 150-MHz observations carried out with the
LOw Frequency ARray (LOFAR), allowing us to explore a new spectral window for
the faint radio source population. This 150-MHz image covers an area of 34.7
square degrees with a resolution of 18.6$\times$14.7 arcsec and reaches an rms
of 160 $\mu$Jy beam$^{-1}$ at the centre of the field.
  As expected for a low-frequency selected sample, the vast majority of sources
exhibit steep spectra, with a median spectral index of
$\alpha_{150}^{1400}=-0.78\pm0.015$. The median spectral index becomes slightly
flatter (increasing from $\alpha_{150}^{1400}=-0.84$ to
$\alpha_{150}^{1400}=-0.75$) with decreasing flux density down to $S_{150}
\sim$10 mJy before flattening out and remaining constant below this flux level.
For a bright subset of the 150-MHz selected sample we can trace the spectral
properties down to lower frequencies using 60-MHz LOFAR observations, finding
tentative evidence for sources to become flatter in spectrum between 60 and 150
MHz. Using the deep, multi-frequency data available in the Lockman Hole, we
identify a sample of 100 Ultra-steep spectrum (USS) sources and 13 peaked
spectrum sources. We estimate that up to 21 percent of these could have $z>4$
and are candidate high-$z$ radio galaxies, but further follow-up observations
are required to confirm the physical nature of these objects.


title: In-orbit performance of AstroSat CZTI

abstract:
  Cadmium-Zinc-Telluride Imager (CZTI) is one of the five payloads on-board
recently launched Indian astronomy satellite AstroSat. CZTI is primarily
designed for simultaneous hard X-ray imaging and spectroscopy of celestial
X-ray sources. It employs the technique of coded mask imaging for measuring
spectra in the energy range of 20 - 150 keV. It was the first scientific
payload of AstroSat to be switched on after one week of the launch and was made
operational during the subsequent week. Here we present preliminary results
from the performance verification phase observations and discuss the in-orbit
performance of CZTI.