title: Walking on exoplanets: Is Star Wars right?

abstract:
  As the number of detected extrasolar planets increases, exoplanet databases
become a valuable resource, confirming some details about planetary formation,
but also challenging our theories with new unexpected properties.


title:
Do the stellar populations of the brightest two group galaxies depend on
  the magnitude gap?

abstract:
  We investigate how the stellar populations of the inner regions of the first
and the second brightest group galaxies (respectively BGGs and SBGGs) vary as a
function of magnitude gap, using an SDSS-based sample of 550 groups with
elliptical BGGs. The sample is complete in redshift, luminosity and for $\Delta
\mathcal{M}_{12}$ up to 2.5 mag, and contains 59 large-gap groups (LGGs, with
$\Delta \mathcal{M}_{12} > 2.0$ mag). We determine ages, metallicities, and
SFHs of BGGs and SBGGs using the STARLIGHT code with two different single
stellar population models (which lead to important disagreements in SFHs), and
also compute $[\alpha/{\rm Fe}]$ from spectral indices. After removing the
dependence with galaxy velocity dispersion or with stellar mass, there is no
correlation with magnitude gap of BGG ages, metallicities, $[\alpha/{\rm Fe}]$,
and SFHs. The lack of trends of BGG SFHs with magnitude gap suggests that BGGs
in LGGs have undergone more mergers than those in small-gap groups, but these
mergers are either dry or occurred at very high redshift, which in either case
would leave no detectable imprint in their spectra. We show that SBGGs in LGGs
lie significantly closer to the BGGs (in projection) than galaxies with similar
stellar masses in normal groups, which appears to be a sign of the earlier
entry of the former into their groups. Nevertheless, the stellar population
properties of the SBGGs in LGGs are compatible with those of the general
population of galaxies with similar stellar masses residing in normal groups.


title: Generating potassium abundance variations in the Solar Nebula

abstract:
  An intriguing aspect of chondritic meteorites is that they are complementary:
while their separate components have wildly varying abundances, bulk chondrites
have nearly solar composition. This implies that the nearly-solar reservoirs in
which chondrites were born were in turn assembled from sub-reservoirs of
differing compositions that birthed the different components. We focus on
explaining the potassium abundance variations between chondrules even within a
single chondrite, while maintaining the observed CI $^{41}$K to $^{39}$K
ratios. This requires physically separating potassium and chondrules while the
temperature is high enough for K to be in the gas phase. We examine several
mechanisms which could drive the dust through gas and show that to do so
locally would have required long (sub-orbital to many orbits) time scales; with
shortest potassium depletion time scales occurring in a scenario where
chondrules formed high above the midplane and settled out of the evaporated
potassium. While orbital time scales are at odds with laboratory chondrule
cooling rate estimates, any other model for the origin for the potassium
abundance variation has to wrestle with the severe logistical difficulty of
generating a plethora of correlated reservoirs which varied strongly in their
potassium abundances, but not in their potassium isotope ratios.


title:
A model to identify urban traffic congestion hotspots in complex
  networks

abstract:
  Traffic congestion is one of the most notable problems arising in worldwide
urban areas, importantly compromising human mobility and air quality. Current
technologies to sense real-time data about cities, and its open distribution
for analysis, allow the advent of new approaches for improvement and control.
Here, we propose an idealized model, the Microscopic Congestion Model, based on
the critical phenomena arising in complex networks, that allows to analytically
predict congestion hotspots in urban environments. Results on real cities' road
networks, considering, in some experiments, real-traffic data, show that the
proposed model is capable of identifying susceptible junctions that might
become hotspots if mobility demand increases.


title: Decongestion of urban areas with hotspot-pricing

abstract:
  The rapid growth of population in urban areas is jeopardizing the mobility
and air quality worldwide. One of the most notable problems arising is that of
traffic congestion which in turn affects air pollution. With the advent of
technologies able to sense real-time data about cities, and its public
distribution for analysis, we are in place to forecast scenarios valuable to
ameliorate and control congestion. Here, we analyze a local congestion pricing
scheme, hotspot pricing, that surcharges vehicles traversing congested
junctions. The proposed tax is computed from the estimation of the evolution of
congestion at local level, and the expected response of users to the tax
(elasticity). Results on cities' road networks, considering real-traffic data,
show that the proposed hotspot pricing scheme would be more effective than
current mechanisms to decongest urban areas, and paves the way towards
sustainable congestion in urban areas.


title:
Search for lepton-flavour-violating decays of the Higgs and $Z$ bosons
  with the ATLAS detector

abstract:
  Direct searches for lepton flavour violation in decays of the Higgs and $Z$
bosons with the ATLAS detector at the LHC are presented. The following three
decays are considered: $H\to e\tau$, $H\to\mu\tau$, and $Z\to\mu\tau$. The
searches are based on the data sample of proton--proton collisions collected by
the ATLAS detector corresponding to an integrated luminosity of 20.3 fb$^{-1}$
at a centre-of-mass energy of $\sqrt{s} = 8$ TeV. No significant excess is
observed, and upper limits on the lepton-flavour-violating branching ratios are
set at the 95% confidence level: Br$(H\to e\tau) <$ 1.04%, Br$(H\to\mu\tau) <$
1.43%, and Br$(Z\to\mu\tau) <$ 1.69 $\times$ 10$^{-5}$.


title: 23Na and 1H NMR Relaxometry of Shale at High Magnetic Field

abstract:
  Formation evaluation of unconventional reservoirs is challenging due to the
coexistence of different phases such as kerogen, bitumen, movable and bound
light hydrocarbon and water. Current low-frequency (0.05 T) nuclear magnetic
resonance (NMR) laboratory and logging methods are incapable of quantitatively
separating the different phases. We demonstrate the utility of high-field (9 T)
NMR 2D T1-T2 measurements for separating hydrocarbon and the clay-interacting
aqueous phases in shale based on the difference in the frequency dependence of
the spin-lattice relaxation time. Furthermore, we demonstrate 23Na NMR as a
promising complementary technique to conventional 1H NMR for shale fluid
typing, taking advantage of the fact that sodium ions are only present in the
aqueous phase. We validate high-field (9 T) 23Na-1H NMR relaxometry for
assessing brine-filled porosity and brine salinity in various porous materials,
including porous glass, conventional rocks, clays, and shale, and apply it for
differentiating hydrocarbon versus aqueous components and also the
clay-associated versus free water in Eagle Ford shale cores. This work lays the
groundwork for developing future downhole 23Na-1H NMR logging techniques.


title: Convergence of sequences of linear operators and their spectra

abstract:
  We establish spectral convergence results of approximations of unbounded
non-selfadjoint linear operators with compact resolvents by operators that
converge in generalized strong resolvent sense. The aim is to establish general
assumptions that ensure spectral exactness, i.e. that every true eigenvalue is
approximated and no spurious eigenvalues occur. A main ingredient is the
discrete compactness of the sequence of resolvents of the approximating
operators. We establish sufficient conditions and perturbation results for
strong convergence and for discrete compactness of the resolvents.


title: On relations between the classes $\mathcal S$ and $\mathcal U$

abstract:
  Let ${\mathcal A}$ denote the family of all functions $f$ analytic in the
unit disk $\ID$ and satisfying the normalization $f(0)=0= f'(0)-1$. Let
$\mathcal{S}$ denote the subclass of ${\mathcal A}$ consisting of univalent
functions in $\ID$. We consider the subclass $\mathcal{U} $ of $\mathcal{S}$
that is defined by the condition that for its members $f$ the condition $$\left
|\left (\frac{z}{f(z)} \right )^{2}f'(z)-1\right | < 1 ~\mbox{ for $z\in \ID$}
$$ holds. To theses relations belong striking similarities and on the other
hand big differences. We show that some results about $\mathcal{S}$ can be
improved for $\mathcal{U}$, while others cannot.


title: From local to non-local correlations: the Dual Boson perspective

abstract:
  Extended dynamical mean-field theory (EDMFT) is insufficient to describe
non-local effects in strongly correlated systems, since corrections to the
mean-field solution are generally large. We present an efficient scheme for the
construction of diagrammatic extensions of EDMFT that avoids usual double
counting problem by using an exact change of variables (the dual boson
formalism) to distinguish the correlations included in the mean-field solution
and those beyond. With a computational efficiency comparable to EDMFT+GW
approach, our scheme significantly improves on the charge order transition
phase boundary in the extended Hubbard model.


title: A Widom-Rowlinson Jump Dynamics in the Continuum

abstract:
  We study the dynamics of an infinite system of point particles of two types.
They perform random jumps in $\mathbf{R}^d$ in the course of which particles of
different types repel each other whereas those of the same type do not
interact. The states of the system are probability measures on the
corresponding configuration space, the global (in time) evolution of which is
constructed by means of correlation functions. It is proved that for each
initial sub-Poissonian state $\mu_0$, the states evolve $\mu_0 \mapsto \mu_t$
in such a way that $\mu_t$ is sub-Poissonian for all $t>0$. The mesoscopic
(approximate) description of the evolution of states is also given. The
stability of translation invariant stationary states is studied. In particular,
we show that some of such states can be unstable with respect to
space-dependent perturbations.


title:
Boundary action of automaton groups without singular points and Wang
  tilings

abstract:
  We study automaton groups without singular points, that is, points in the
boundary for which the map that associates to each point its stabilizer, is not
continuous. This is motivated by the problem of finding examples of infinite
bireversible automaton groups with all trivial stabilizers in the boundary,
raised by Grigorchuk and Savchuk. We show that, in general, the set of singular
points has measure zero. Then we focus our attention on several classes of
automata. We characterize those contracting automata generating groups without
singular points, and apply this characterization to the Basilica group. We
prove that potential examples of reversible automata generating infinite groups
without singular points are necessarily bireversible. Then we provide some
necessary conditions for such examples to exist, and study some dynamical
properties of their Schreier graphs in the boundary. Finally we relate some of
those automata with aperiodic tilings of the discrete plane via Wang tilings.
This has a series of consequences from the algorithmic and dynamical points of
view, and is related to a problem of Gromov regarding the searching for
examples of CAT(0) complexes whose fundamental groups are not hyperbolic and
contain no subgroup isomorphic to $\mathbb{Z}^{2}$.


title: Stable blowup for the supercritical Yang-Mills heat flow

abstract:
  In this paper, we consider the heat flow for Yang-Mills connections on
$\mathbb{R}^5 \times SO(5)$. In the $SO(5)-$equivariant setting, the Yang-Mills
heat equation reduces to a single semilinear reaction-diffusion equation for
which an explicit self-similar blowup solution was found by Weinkove
\cite{Wei04}. We prove the nonlinear asymptotic stability of this solution
under small perturbations. In particular, we show that there exists an open set
of initial conditions in a suitable topology such that the corresponding
solutions blow up in finite time and converge to a non-trivial self-similar
blowup profile on an unbounded domain. Convergence is obtained in suitable
Sobolev norms and in $L^{\infty}$.


title:
Development and testing of cost-effective, 6 cm x 6 cm MCP-based
  photodetectors for fast timing applications

abstract:
  Micro-channel plate (MCP)-based photodetectors are capable of picosecond
level time resolution and sub-mm level position resolution, which makes them a
perfect candidate for the next generation large area photodetectors. The
large-area picosecond photodetector (LAPPD) collaboration is developing new
techniques for making large-area photodetectors based on new MCP fabrication
and functionalization methods. A small single tube processing system (SmSTPS)
was constructed at Argonne National Laboratory (ANL) for developing scalable,
cost-effective, glass-body, 6 cm x 6 cm, picosecond photodetectors based on
MCPs functionalized by Atomic Layer Deposition (ALD). Recently, a number of
fully processed and hermitically sealed prototypes made of MCPs with 20 micron
pores have been fabricated. This is a significant milestone for the LAPPD
project. These prototypes were characterized with a pulsed laser test facility.
Without optimization, the prototypes have shown excellent results: The time
resolution is ~57 ps for single photoelectron mode and ~15 ps for
multi-photoelectron mode; the best position resolution is < 0.8 mm for large
pulses. In this paper, the tube processing system, the detector assembly,
experimental setup, data analysis and the key performance will be presented.


title: Extended eigenvarieties for overconvergent cohomology

abstract:
  Recently, Andreatta, Iovita and Pilloni have constructed spaces of
overconvergent modular forms in characteristic p, together with a natural
extension of the Coleman-Mazur eigencurve over a compactified (adic) weight
space. Similar ideas have also been used by Liu, Wan and Xiao to study the
boundary of the eigencurve. This all goes back to an idea of Coleman.
  In this article, we construct natural extensions of eigenvarieties for
arbitrary reductive groups G over a number field which are split at all places
above p. If G is GL(2)/Q, then we obtain a new construction of the extended
eigencurve of Andreatta-Iovita-Pilloni. If G is an inner form of GL(2)
associated to a definite quaternion algebra, our work gives a new perspective
on some of the results of Liu-Wan-Xiao.
  We build our extended eigenvarieties following Hansen's construction using
overconvergent cohomology. One key ingredient is a definition of locally
analytic distribution modules which permits coefficients of characteristic p
(and mixed characteristic). When G is GL(n) over a totally real or CM number
field, we also construct a family of Galois representations over the reduced
extended eigenvariety.


title: Baryogenesis from leptomesons

abstract:
  Various new physics models, e.g., theories of compositeness, can accommodate
the color singlet excited leptons that interact with the leptons, quarks,
leptoquarks, etc. A particular type of excited lepton, which at low energies
interacts with the Standard Model fermions mainly through the four-fermion
coupling to lepton and quark-antiquark (or lepton-antilepton) pair, we call
leptomeson. These new particles may contribute to variety of the experimental
anomalies such as the discrepancy in the muon g-2. We propose that the
leptomesons can generate also the baryon asymmetry that explains the imbalance
in ordinary matter and antimatter in the observable universe. We consider the
two types of scenarios for this baryogenesis via leptogenesis to occur from
either leptomeson oscillations or decays. Both possibilities do not contradict
to the small masses of the observable neutrinos and the proton stability.
Moreover they can be relevant for the near future collider experiments and do
not suffer from the gravitino problem.


title: EgoSampling: Wide View Hyperlapse from Egocentric Videos

abstract:
  The possibility of sharing one's point of view makes use of wearable cameras
compelling. These videos are often long, boring and coupled with extreme shake,
as the camera is worn on a moving person. Fast forwarding (i.e. frame sampling)
is a natural choice for quick video browsing. However, this accentuates the
shake caused by natural head motion in an egocentric video, making the fast
forwarded video useless. We propose EgoSampling, an adaptive frame sampling
that gives stable, fast forwarded, hyperlapse videos. Adaptive frame sampling
is formulated as an energy minimization problem, whose optimal solution can be
found in polynomial time. We further turn the camera shake from a drawback into
a feature, enabling the increase in field-of-view of the output video. This is
obtained when each output frame is mosaiced from several input frames. The
proposed technique also enables the generation of a single hyperlapse video
from multiple egocentric videos, allowing even faster video consumption.


title: Relativistic stars in scalar-tensor theories with disformal coupling

abstract:
  We present a general formulation to analyze the structure of slowly rotating
relativistic stars in a broad class of scalar-tensor theories with disformal
coupling to matter. Our approach includes theories with generalized kinetic
terms, generic scalar field potentials and contains theories with conformal
coupling as particular limits. In order to investigate how the disformal
coupling affects the structure of relativistic stars, we propose a minimal
model of a massless scalar-tensor theory and investigate in detail how the
disformal coupling affects the spontaneous scalarization of slowly rotating
neutron stars. We show that for negative values of the disformal coupling
parameter between the scalar field and matter, scalarization can be suppressed,
while for large positive values of the disformal coupling parameter stellar
models cannot be obtained. This allows us to put a mild upper bound on this
parameter. We also show that these properties can be qualitatively understood
by linearizing the scalar field equation of motion in the background of a
general-relativistic incompressible star. To address the intrinsic degeneracy
between uncertainties in the equation-of-state of neutron stars and
gravitational theory, we also show the existence of universal
equation-of-state-independent relations between the moment of inertia and
compactness of neutron stars in this theory. We show that in a certain range of
the theory's parameter space the universal relation largely deviates from that
of general relativity, allowing, in principle, to probe the existence of
spontaneous scalarization with future observations.


title:
Saturation and solvability in abstract elementary classes with
  amalgamation

abstract:
  $\mathbf{Theorem.}$
  Let $K$ be an abstract elementary class (AEC) with amalgamation and no
maximal models. Let $\lambda > \text{LS} (K)$. If $K$ is categorical in
$\lambda$, then the model of cardinality $\lambda$ is Galois-saturated.
  This answers a question asked independently by Baldwin and Shelah. We deduce
several corollaries: $K$ has a unique limit model in each cardinal below
$\lambda$, (when $\lambda$ is big-enough) $K$ is weakly tame below $\lambda$,
and the thresholds of several existing categoricity transfers can be improved.
  We also prove a downward transfer of solvability (a version of superstability
introduced by Shelah):
  $\mathbf{Corollary.}$
  Let $K$ be an AEC with amalgamation and no maximal models. Let $\lambda > \mu
> \text{LS} (K)$. If $K$ is solvable in $\lambda$, then $K$ is solvable in
$\mu$.


title:
Exceptional Points in a non-Hermitian extension of the Jaynes-Cummings
  Hamiltonian

abstract:
  We consider a generalization of the non-Hermitian ${\mathcal PT}$ symmetric
Jaynes-Cummings {Hamiltonian, recently introduced for studying optical
phenomena with time-dependent physical parameters, that includes
environment-induced decay}. In particular, we investigate the interaction of a
two-level fermionic system (such as a two-level atom) with a single bosonic
field mode in a cavity. The states of {the} two-level system are allowed to
decay because of the interaction with the environment, {and this is included
phenomenologically in our non-Hermitian Hamiltonian by introducing complex
energies for the fermion system. We focus our attention} on the occurrence of
exceptional points in the spectrum of the Hamiltonian, clarifying its
mathematical and physical meaning.


title: The semantics of the canonical commutation relation

abstract:
  We treat the canonical commutation relations and the conventional calculus
based on it as an algebraic syntax of quantum mechanics and establish a
geometric semantics of this syntax. This leads us to a geometric model, the
space of states with the action of time evolution operators, which is a limit
of finite models. The finitary nature of the space allows to give a precise
meaning and calculate various classical quantum mechanical quantities.


title: Newer sums of three cubes

abstract:
  The search of solutions of the Diophantine equation $x^3 + y^3 + z^3 = k$ for
$k<1000$ has been extended with bounds of $|x|$, $|y|$ and $|z|$ up to
$10^{15}$. The first solution for $k=74$ is reported. This only leaves $k=33$
and $k=42$ for $k<100$ for which no solution has yet been found. A total of 966
new solutions were found.


title:
Modulated spin helicity stabilized by incommensurate orbital density
  waves in a quadruple perovskite manganite

abstract:
  Through a combination of neutron diffraction and Landau theory we describe
the spin ordering in the ground state of the quadruple perovskite manganite
CaMn7O12 - a magnetic multiferroic supporting an incommensurate orbital density
wave that onsets above the magnetic ordering temperature, TN1 = 90 K. The
multi-k magnetic structure in the ground state was found to be a
nearly-constant-moment helix with modulated spin helicity, which oscillates in
phase with the orbital occupancies on the Mn3+ sites via trilinear
magneto-orbital coupling. Our phenomenological model also shows that, above TN2
= 48 K, the primary magnetic order parameter is locked into the orbital wave by
an admixture of helical and collinear spin density wave structures.
Furthermore, our model naturally explains the lack of a sharp dielectric
anomaly at TN1 and the unusual temperature dependence of the electrical
polarisation.


title: Quantum twist maps and dual canonical bases

abstract:
  In this paper, we show that quantum twist maps, introduced by
Lenagan-Yakimov, induce bijections between dual canonical bases of quantum
nilpotent subalgebras. As a corollary, we show the unitriangular property
between dual canonical bases and Poincar\'e-Birkhoff-Witt type bases under the
"reverse" lexicographic order. We also show that quantum twist maps induce
bijections between certain unipotent quantum minors.


title: Hot subluminous stars

abstract:
  Hot subluminous stars of spectral type B and O are core helium-burning stars
at the blue end of the horizontal branch or have evolved even beyond that
stage. Strikingly, the distribution in the Hertzsprung-Russell diagram of
He-rich vs. He-poor hot subdwarf stars of the globular clusters omega Cen and
NGC~2808 differ from that of their field counterparts. The metal-abundance
patterns of hot subdwarfs are typically characterized by strong deficiencies of
some lighter elements as well as large enrichments of heavy elements. A large
fraction of sdB stars are found in close binaries with white dwarf or very
low-mass main sequence companions, which must have gone through a
common-envelope phase of evolution.They provide a clean-cut laboratory to study
this important but yet purely understood phase of stellar evolution. Substellar
companions to sdB stars have also been found. For HW~Vir systems the companion
mass distribution extends from the stellar into the brown dwarf regime. A giant
planet to the pulsator V391 Peg was the first discovery of a planet that
survived the red giant evolution of its host star. Several types of pulsating
star have been discovered among hot subdwarf stars, the most common are the
gravity-mode sdB pulsators (V1093 Her) and their hotter siblings, the p-mode
pulsating V361 Hya stars. Another class of multi-periodic pulsating hot
subdwarfs has been found in the globular cluster omega Cen that is unmatched by
any field star. The masses of hot subdwarf stars are the key to understand the
stars' evolution. A few pulsating sdB stars in eclipsing binaries have been
found that allow mass determination. The results are in good agreement with
predictions from binary population synthesis. New classes of binaries, hosting
extremely low mass (ELM) white dwarfs (M<0.3 Msun), have recently been
discovered, filling a gap in the mosaic of binary stellar evolution.
(abbreviated)


title:
Extreme value analysis for the sample autocovariance matrices of
  heavy-tailed multivariate time series

abstract:
  We provide some asymptotic theory for the largest eigenvalues of a sample
covariance matrix of a p-dimensional time series where the dimension p = p_n
converges to infinity when the sample size n increases. We give a short
overview of the literature on the topic both in the light- and heavy-tailed
cases when the data have finite (infinite) fourth moment, respectively. Our
main focus is on the heavytailed case. In this case, one has a theory for the
point process of the normalized eigenvalues of the sample covariance matrix in
the iid case but also when rows and columns of the data are linearly dependent.
We provide limit results for the weak convergence of these point processes to
Poisson or cluster Poisson processes. Based on this convergence we can also
derive the limit laws of various function als of the ordered eigenvalues such
as the joint convergence of a finite number of the largest order statistics,
the joint limit law of the largest eigenvalue and the trace, limit laws for
successive ratios of ordered eigenvalues, etc. We also develop some limit
theory for the singular values of the sample autocovariance matrices and their
sums of squares. The theory is illustrated for simulated data and for the
components of the S&P 500 stock index.


title: Compressive phase-only filtering at extreme compression rates

abstract:
  We introduce an efficient method for the reconstruction of the correlation
between a compressively measured image and a phase-only filter. The proposed
method is based on two properties of phase-only filtering: such filtering is a
unitary circulant transform, and the correlation plane it produces is usually
sparse. Thanks to these properties, phase-only filters are perfectly compatible
with the framework of compressive sensing. Moreover, the lasso-based recovery
algorithm is very fast when phase-only filtering is used as the compression
matrix. The proposed method can be seen as a generalisation of the
correlation-based pattern recognition technique, which is hereby applied
directly to non-adaptively acquired compressed data. At the time of
measurement, any prior knowledge of the target object for which the data will
be scanned is not required. We show that images measured at extremely high
compression rates may still contain sufficient information for target
classification and localization, even if the compression rate is high enough,
that visual recognition of the target in the reconstructed image is no longer
possible. The method has been applied by us to highly undersampled measurements
obtained from a single-pixel camera, with sampling based on randomly chosen
Walsh-Hadamard patterns.


title:
Disc-Jet Coupling in the Terzan 5 Neutron Star X-ray Binary EXO
  1745$-$248

abstract:
  We present the results of VLA, ATCA, and Swift XRT observations of the 2015
outburst of the transient neutron star X-ray binary (NSXB), EXO 1745$-$248,
located in the globular cluster Terzan 5. Combining (near-) simultaneous radio
and X-ray measurements we measure a correlation between the radio and X-ray
luminosities of $L_R\propto L_X^\beta$ with $\beta=1.68^{+0.10}_{-0.09}$,
linking the accretion flow (probed by X-ray luminosity) and the compact jet
(probed by radio luminosity). While such a relationship has been studied in
multiple black hole X-ray binaries (BHXBs), this work marks only the third NSXB
with such a measurement. Constraints on this relationship in NSXBs are strongly
needed, as comparing this correlation between different classes of XB systems
is key in understanding the properties that affect the jet production process
in accreting objects. Our best fit disc-jet coupling index for EXO 1745$-$248
is consistent with the measured correlation in NSXB 4U 1728$-$34 ($\beta=1.5\pm
0.2$) but inconsistent with the correlation we fit using the most recent
measurements from the literature of NSXB Aql X-1
($\beta=0.76^{+0.14}_{-0.15}$). While a similar disc-jet coupling index appears
to hold across multiple BHXBs in the hard accretion state, this does not appear
to be the case with the three NSXBs measured so far. Additionally, the
normalization of the EXO 1745$-$248 correlation is lower than the other two
NSXBs, making it one of the most radio faint XBs ever detected in the hard
state. We also report the detection of a type-I X-ray burst during this
outburst, where the decay timescale is consistent with hydrogen burning.


title:
Particle creation phenomenology, Dirac sea and the induced Weyl and
  Einstein-dilaton gravity

abstract:
  We constructed the conformally invariant model for scalar particle creation
induced by strong gravitational fields. Starting from the "usual"
hydrodynamical description of the particle motion written in the Eulerian
coordinates we substituted the particle number conservation law (which enters
the formalism) by "the particle creation law", proportional to the square of
the Weyl tensor (following the famous result by Ya.B.Zel`dovich and A.
A.Starobinsky). Then, demanding the conformal invariance of the whole dynamical
system, we have got both the (Weyl)-conformal gravity and the Einstein--Hilbert
gravity action integral with dilaton field. Thus, we obtained something like
the induced gravity suggested first by A. D.Sakharov. It is shown that the
resulting system is self-consistent. We considered also the vacuum equations.
It is shown that, beside the "empty vacuum", there may exist the "dynamical
vacuum", which is nothing more but the Dirac sea.


title:
Bypassing the Groenewold-van Hove Obstruction: A New Argument in Favor
  of Born-Jordan Quantization

abstract:
  There are known obstructions to a full quantization in the spirit of Dirac's
approach, the most known being the Groenewold-van Hove no-go result. We show,
following a suggestion of S. K. Kauffmann, that it is possible to construct a
well-defined quantization procedure by weakening the usual requirement that
commutators should correspond to Poisson brackets. The weaker requirement
consists in demanding that this correspondence should only hold for Hamiltonian
functions of the type T(p)+V(q). This reformulation leads to a non-injective
quantization of all observables which, when restricted to polynomials, is the
rule proposed by Born and Jordan in the early days of quantum mechanics.


title:
On fractional elliptic equations in Lipschitz sets and epigraphs:
  regularity, monotonicity and rigidity results

abstract:
  We consider a nonlocal equation set in an unbounded domain with the epigraph
property. We prove symmetry, monotonicity and rigidity results. In particular,
we deal with halfspaces, coercive epigraphs and epigraphs that are flat at
infinity.


title:
Electromagnetic Scattering for Time-Domain Maxwell's Equations in an
  Unbounded Structure

abstract:
  The goal of this work is to study the electromagnetic scattering problem of
time-domain Maxwell's equations in an unbounded structure. An exact transparent
boundary condition is developed to reformulate the scattering problem into an
initial-boundary value problem in an infinite rectangular slab. The
well-posedness and stability are established for the reduced problem. Our proof
is based on the method of energy, the Lax--Milgram lemma, and the inversion
theorem of the Laplace transform. Moreover, a priori estimates with explicit
dependence on the time are achieved for the electric field by directly studying
the time-domain Maxwell equations.


title: Surface Nematic Order in Iron Pnictides

abstract:
  Electronic nematicity plays important role in iron-based superconductors.
These materials have layered structure and theoretical description of their
magnetic and nematic transitions has been well established in two-dimensional
approximation, i.e., when the layers can be treated independently. However, the
interaction between iron layers mediated by electron tunneling may cause
non-trivial three-dimensional behavior. Starting from the simplest model for
orbital nematic in a single layer, we investigate the influence of interlayer
tunneling on bulk nematic order and possible preemptive state where this order
is only formed near the surface.
  We found that the interlayer tunneling suppresses the bulk nematicity which
makes favorable formation of a surface nematic above the bulk transition
temperature. The purely electronic tunneling Hamiltonian, however, favors
alternating from layer-to-layer nematic order parameter in the bulk. The
uniform bulk state typically observed experimentally may be stabilized by the
coupling with the elastic lattice deformation. Depending on strength of this
coupling, we found three regimes: (i) surface nematic and alternating bulk
order, (ii) surface nematic and uniform bulk order, and (iii) uniform bulk
order without the intermediate surface phase. The intermediate surface-nematic
state may resolve the current controversy about the existence of the weak
"meta-nematic transition" in the compound BaFe$_2$As$_{2-x}$P$_{x}$.


title:
Curvature inequalities for operators in the Cowen-Douglas class of a
  planar domain

abstract:
  Fix a bounded planar domain $\Omega.$ If an operator $T,$ in the
Cowen-Douglas class $B_1(\Omega),$ admits the compact set $\bar{\Omega}$ as a
spectral set, then the curvature inequality $\mathcal K_T(w) \leq - 4 \pi^2
S_\Omega(w,w)^2,$ where $S_\Omega$ is the S\"{z}ego kernel of the domain
$\Omega,$ is evident. Except when $\Omega$ is simply connected, the existence
of an operator for which $\mathcal K_T(w) = 4 \pi^2 S_\Omega(w,w)^2$ for all
$w$ in $\Omega$ is not known. However, one knows that if $w$ is a fixed but
arbitrary point in $\Omega,$ then there exists a bundle shift of rank $1,$ say
$S,$ depending on this $w,$ such that $\mathcal K_{S^*}(w) = 4 \pi^2
S_\Omega(w,w)^2.$ We prove that these {\em extremal} operators are uniquely
determined: If $T_1$ and $T_2$ are two operators in $B_1(\Omega)$ each of which
is the adjoint of a rank $1$ bundle shift and $\mathcal{K}_{T_1}({w}) = -4\pi
^2 S(w,w)^2 = \mathcal{K}_{T_2}(w)$ for a fixed $w$ in $\Omega,$ then $T_1$ and
$T_2$ are unitarily equivalent. A surprising consequence is that the adjoint of
only some of the bundle shifts of rank $1$ occur as extremal operators in
domains of connectivity greater than $1.$ These are described explicitly.


title:
F-measure Maximization in Multi-Label Classification with Conditionally
  Independent Label Subsets

abstract:
  We discuss a method to improve the exact F-measure maximization algorithm
called GFM, proposed in (Dembczynski et al. 2011) for multi-label
classification, assuming the label set can be can partitioned into
conditionally independent subsets given the input features. If the labels were
all independent, the estimation of only $m$ parameters ($m$ denoting the number
of labels) would suffice to derive Bayes-optimal predictions in $O(m^2)$
operations. In the general case, $m^2+1$ parameters are required by GFM, to
solve the problem in $O(m^3)$ operations. In this work, we show that the number
of parameters can be reduced further to $m^2/n$, in the best case, assuming the
label set can be partitioned into $n$ conditionally independent subsets. As
this label partition needs to be estimated from the data beforehand, we use
first the procedure proposed in (Gasse et al. 2015) that finds such partition
and then infer the required parameters locally in each label subset. The latter
are aggregated and serve as input to GFM to form the Bayes-optimal prediction.
We show on a synthetic experiment that the reduction in the number of
parameters brings about significant benefits in terms of performance.


title:
Spectral Anisotropy of Els\"asser Variables in Two Dimensional
  Wave-vector Space as Observed in the Fast Solar Wind Turbulence

abstract:
  Intensive studies have been conducted to understand the anisotropy of solar
wind turbulence. However, the anisotropy of Els\"asser variables
($\textbf{Z}^\pm$) in 2D wave-vector space has yet to be investigated. Here we
first verify the transformation based on the projection-slice theorem between
the power spectral density PSD$_{2D}(k_\parallel,k_\perp )$ and the spatial
correlation function CF$_{2D} (r_\parallel,r_\perp )$. Based on the application
of the transformation to the magnetic field and the particle measurements from
the WIND spacecraft, we investigate the spectral anisotropy of Els\"asser
variables ($\textbf{Z}^\pm$), and the distribution of residual energy E$_{R}$,
Alfv\'en ratio R$_{A}$ and Els\"asser ratio R$_{E}$ in the
$(k_\parallel,k_\perp)$ space. The spectra PSD$_{2D}(k_\parallel,k_\perp )$ of
$\textbf{B}$, $\textbf{V}$, and $\textbf{Z}_{major}$ (the larger of
$\textbf{Z}^\pm$) show a similar pattern that PSD$_{2D}(k_\parallel,k_\perp )$
is mainly distributed along a ridge inclined toward the $k_\perp$ axis. This is
probably the signature of the oblique Alfv\'enic fluctuations propagating
outwardly. Unlike those of $\textbf{B}$, $\textbf{V}$, and
$\textbf{Z}_{major}$, the spectrum PSD$_{2D}(k_\parallel,k_\perp )$ of
$\textbf{Z}_{minor}$ is distributed mainly along the $k_\perp$ axis. Close to
the $k_\perp$ axis, $\left| {E}_{R}\right|$ becomes larger while R$_{A}$
becomes smaller, suggesting that the dominance of magnetic energy over kinetic
energy becomes more significant at small $k_\parallel$. R$_{E}$ is larger at
small $k_\parallel$, implying that PSD$_{2D}(k_\parallel,k_\perp )$ of
$\textbf{Z}_{minor}$ is more concentrated along the $k_\perp$ direction as
compared to that of $\textbf{Z}_{major}$. The residual energy condensate at
small $k_\parallel$ is consistent with simulation results in which E$_{R}$ is
spontaneously generated by Alfv\'en wave interaction.


title:
The Chemical Evolution of Galaxies: The Stellar Mass-Metallicity
  Relation

abstract:
  The predictions of the multiple burst accretion model of chemical evolution
are compared to the observations of the stellar masses and metallicities of
star-forming galaxies. With the addition of one parameter, the model can
account for the observations of the star-forming galaxies if the observations
of the galaxies are identified with the star bursting behaviour of the model.
This consistency with the model holds only if galaxy downsizing is assumed to
occur.


title:
Strong turbulent convection: distributed chaos and large-scale
  circulation

abstract:
  Two types of spontaneous breaking of the space translational symmetry in
distributed chaos have been considered for turbulent thermal convection at
large values of Rayleigh number. First type is related to boundaries and second
type is related to appearance of inertial range of scales. The first type is
dominated by vorticity correlation integral: $\int_{V} \langle {\boldsymbol
\omega} ({\bf x},t) \cdot {\boldsymbol \omega} ({\bf x} + {\bf r},t)
\rangle_{V} d{\bf r}$ and is characterized by stretched exponential spectrum
$\exp-(k/k_{\beta})^{\beta }$ with $\beta =1/2$. The second type is dominated
by energy correlation integral: $\int_{V} \langle {\bf u}^2 ({\bf x},t) ~ {\bf
u}^2({\bf x} + {\bf r},t) \rangle_{V} d{\bf r}$ and is characterized by $\beta
=3/5$. Good agreement has been established with laboratory experimental data
obtained at large values of Rayleigh number $Ra \sim 10^{11}-10^{14}$ (the
range relevant to solar photosphere) in upright cylinder cells. Taylor
hypothesis transforms the wavenumber spectrum into frequency spectrum
$\exp-(f/f_{\beta})^{1/2}$. It is shown that turnover frequency of large-scale
circulation (wind): $f_w = f_{\beta}/2$. Results of an experiment in horizontal
cylinder are also briefly discussed. The analysis suggests that in this case
the large-scale circulation can be considered as a natural (harmonic) part of
the distributed chaos.


title:
Galactic Archaeology with asteroseismology and spectroscopy: Red giants
  observed by CoRoT and APOGEE

abstract:
  With the advent of the space missions CoRoT and Kepler, it has become
feasible to determine precise asteroseismic masses and ages for large samples
of red-giant stars. In this paper, we present the CoRoGEE dataset -- obtained
from CoRoT lightcurves for 606 red giant stars in two fields of the Galactic
disc which have been co-observed for an ancillary project of APOGEE. We have
used the Bayesian parameter estimation code PARAM to calculate distances,
extinctions, masses, and ages for these stars in a homogeneous analysis,
resulting in relative statistical uncertainties of $\sim2\%$ in distance,
$\sim4\%$ in radius, $\sim9\%$ in mass and $\sim25\%$ in age. We also assess
systematic age uncertainties due to different input physics and mass loss. We
discuss the correlation between ages and chemical abundance patterns of field
stars over a large radial range of the Milky Way's disc (5 kpc $<R_{\rm Gal}<$
14 kpc), focussing on the [$\alpha$/Fe]-[Fe/H]-age plane in five radial bins of
the Galactic disc. We find an overall agreement with the expectations of
chemical-evolution models computed before the present data were available,
especially for the outer regions. However, our data also indicate that a
significant fraction of stars now observed near and beyond the Solar
Neighbourhood migrated from inner regions. Mock CoRoGEE observations of a
chemo-dynamical Milky Way disc model show that the number of high-metallicity
stars in the outer disc is too high to be accounted for even by the strong
radial mixing present in the model. The mock observations also reveal that the
age distribution of the [$\alpha$/Fe]-enhanced sequence in the CoRoGEE
inner-disc field is much broader than expected from a combination of radial
mixing and observational errors. We suggest that a thick disc/bulge component
that formed stars for more than 3 Gyr may account for these discrepancies.


title:
Actions, topological terms and boundaries in first order gravity: A
  review

abstract:
  In this review we consider first order gravity in four dimensions. In
particular, we focus our attention in formulations where the fundamental
variables are a tetrad $e_a^I$ and a SO(3,1) connection ${\omega_{aI}}^J$. We
study the most general action principle compatible with diffeomorphism
invariance. This implies, in particular, considering besides the standard
Einstein-Hilbert-Palatini term, other terms that either do not change the
equations of motion, or are topological in nature. Having a well defined action
principle sometimes involves the need for additional boundary terms, whose
detailed form may depend on the particular boundary conditions at hand. In this
work, we consider spacetimes that include a boundary at infinity, satisfying
asymptotically flat boundary conditions and/or an internal boundary satisfying
isolated horizons boundary conditions. We focus on the covariant Hamiltonian
formalism where the phase space $\Gamma$ is given by solutions to the equations
of motion. For each of the possible terms contributing to the action we
consider the well posedness of the action, its finiteness, the contribution to
the symplectic structure, and the Hamiltonian and Noether charges. For the
chosen boundary conditions, standard boundary terms warrant a well posed
theory. Furthermore, the boundary and topological terms do not contribute to
the symplectic structure, nor the Hamiltonian conserved charges. The Noether
conserved charges, on the other hand, do depend on such additional terms. The
aim of this manuscript is to present a comprehensive and self-contained
treatment of the subject, so the style is somewhat pedagogical. Furthermore,
along the way we point out and clarify some issues that have not been clearly
understood in the literature.


title:
Fluid/gravity correspondence: Second order transport coefficients in
  compactified D4-branes

abstract:
  We develop the boundary derivative expansion (BDE) formalism of fluid/gravity
correspondence to nonconformal version through the compactified, near-extremal
black D4-brane. We offer an explicit calculation of 9 second order transport
coefficients, i.e., the $\tau_\pi,~\tau_\pi^*,~\tau_\Pi,~\lambda_{1,2,3}$ and
$\xi_{1,2,3}$ for the strongly coupled, uncharged and nonconformal relativistic
fluid which is the holographic dual of compactified, near extremal black
D4-brane. We also show that the nonconformal fluid considered in this work is
free of causal problem and admits the Haack-Yarom relation
$4\lambda_1+\lambda_2=2\eta\tau_\pi$.


title: Towards better understanding of QBism

abstract:
  Recently I posted a paper entitled "External observer reflections on QBism".
As any external observable, I was not able to reflect some features of QBism
properly. Therefore comments which I received from one of its creators, C.
Fuchs, are very valuable - to understand better the views of QBists. Some of
QBism features are very delicate and to extract them from articles of QBists is
not a simple task. Therefore I hope that the second portion of my reflection on
QBism (or better to say my reflections on Fuchs' reflections on my reflections)
might be interesting and useful for other experts in quantum foundations and
quantum information theory (especially by taking into account my previous
aggressively anti-QBism position). In the present paper I correct some of my
previously posted critical comments on QBism. At the same time better
understanding of QBists views on some problems leads to improvement and
strengthening of other critical comments.


title:
Fingerprints of entangled spin and orbital physics in itinerant
  ferromagnets via angle resolved $resonant$ photoemission

abstract:
  A novel method for mapping the local spin and orbital nature of the ground
state of a system via corresponding flip excitations in both sectors is
proposed based on angle resolved resonant photoemission and related diffraction
patterns, presented here for the first time via an ab-initio modified one-step
theory of photoemission. The analysis is done on the paradigmatic weak
itinerant ferromagnet bcc Fe, whose magnetism, seen as a correlation phenomenon
given by the coexistence of localized moments and itinerant electrons, and the
non-Fermi liquid behaviour at ambient and extreme conditions both remain
unclear. The results offer a real space imaging of local pure spin flip and
entangled spin flip-orbital flip excitations (even at energies where spin flip
transitions are hidden in quasiparticle peaks) and of chiral, vortex-like
wavefronts of excited electrons, depending on the orbital character of the
bands and the direction of the local magnetic moment. Such effects, mediated by
the hole polarization, make resonant photoemission a promising tool to perform
a full tomography of the local magnetic properties of a system with a high
sensitivity to localization/correlation, even in itinerant or macroscopically
non magnetic systems.


title:
Increased metallicity of Carbon nanotubes because of incorporation of
  extended Stone-Wales' defects: an ab-initio real space approach

abstract:
  We propose an ab-initio combination of the Linear Muffin-Tin Orbital and the
Recursion Methods to study the effect of extended Stone-Wales defects in single
layer Carbon nanotubes. We have successfully applied this to zigzag and
armchair tubes. The methodology involves no intrinsic mean-field like
assumptions or external parameter fitting. As defects proliferate, the low
density of states near the Fermi levels of the pristine tubes is filled with
defect states. The increase of DOS at the Fermi level leads to enhanced
conduction, which indicates enhanced metallicity due to SW defects in the
nanotubes.


title: An Appropriate Sensor Distribution Technique in Wireless Sensor Networks

abstract:
  Wireless Sensor Network (WSN) is pertinent to many applications with varied
network parameters. Sensor node placement in the application region whether it
is indoor or outdoor is a major task as well as plays very remarkable role in
the network performance. Node placement is carried out according to the region
where it is applied, either deterministic or non deterministic. Because of the
need for different sensing probability or detection probability, same approach
of sensor placement may not be suited for all the applications. Some of the
applications are well formed and give better performance with the uniform
distribution of sensors but few need intense distribution of nodes in
particular sensitive places especially those applications meant for intrusion
detection. An application which needs high level intrusion detection and a
suitable sensor distribution methodology, known as Half-Normal Distribution
(Half-Gaussian) based deployment, have been set forth in this paper. We have
also discussed the theoretical comparison for detection probability with the
uniform distribution in terms of number of sensor nodes.


title:
Characterizing College Science Assessments: The Three-Dimensional
  Learning Assessment Protocol

abstract:
  Many calls to improve science education in college and university settings
have focused on improving instructor pedagogy. Meanwhile, science education at
the K-12 level is undergoing significant changes as a result of the emphasis on
scientific and engineering practices, crosscutting concepts, and disciplinary
core ideas. This framework of "three-dimensional learning" is based on the
literature about how people learn science and how we can help students put
their knowledge to use. Recently, similar changes are underway in higher
education by incorporating three-dimensional learning into college science
courses. As these transformations move forward, it will become important to
assess three-dimensional learning both to align assessments with the learning
environment, and to assess the extent of the transformations. In this paper we
introduce the Three-Dimensional Learning Assessment Protocol (3D-LAP), which is
designed to characterize and support the development of assessment tasks in
biology, chemistry, and physics that align with transformation efforts. We
describe the development process used by our interdisciplinary team, discuss
the validity and reliability of the protocol, and provide evidence that the
protocol can distinguish between assessments that have the potential to elicit
evidence of three-dimensional learning and those that do not.


title:
Galactic Archaeology with CoRoT and APOGEE: Creating mock observations
  from a chemodynamical model

abstract:
  In a companion paper, we have presented the combined
asteroseismic-spectroscopic dataset obtained from CoRoT lightcurves and APOGEE
infra-red spectra for 678 solar-like oscillating red giants in two fields of
the Galactic disc (CoRoGEE). We have measured chemical abundance patterns,
distances, and ages of these field stars which are spread over a large radial
range of the Milky Way's disc. Here we show how to simulate this dataset using
a chemodynamical Galaxy model. We also demonstrate how the observation
procedure influences the accuracy of our estimated ages.


title:
High order recurrence relation, Hermite-Pad\'e approximation, and
  Nikishin systems

abstract:
  The study of sequences of polynomials satisfying high order recurrence
relations is connected with the asymptotic behavior of multiple orthogonal
polynomials, the convergence properties of type II Hermite-Pad\'e
approximation, and eigenvalue distribution of banded Toeplitz matrices. We
present some results for the case of recurrences with constant coefficients
which match what is known for the Chebyshev polynomials of the first kind. In
particular, under appropriate assumptions, we show that the sequence of
polynomials satisfies multiple orthogonality relations with respect to a
Nikishin system of measures.


title:
Search for new phenomena in final states with an energetic jet and large
  missing transverse momentum in $pp$ collisions at $\sqrt{s}=13$ TeV using the
  ATLAS detector

abstract:
  Results of a search for new phenomena in final states with an energetic jet
and large missing transverse momentum are reported. The search uses
proton--proton collision data corresponding to an integrated luminosity of 3.2
fb${}^{-1}$ at $\sqrt{s}=13$ TeV collected in 2015 with the ATLAS detector at
the Large Hadron Collider. Events are required to have at least one jet with a
transverse momentum above 250 GeV and no leptons. Several signal regions are
considered with increasing missing-transverse-momentum requirements between
$E_{\rm T}^{\rm miss} >250$ GeV and $E_{\rm T}^{\rm miss} > 700$ GeV. Good
agreement is observed between the number of events in data and Standard Model
predictions. The results are translated into exclusion limits in models with
large extra spatial dimensions, pair production of weakly interacting
dark-matter candidates, and the production of supersymmetric particles in
several compressed scenarios.


title: Eta quotients, Eisenstein series and Elliptic Curves

abstract:
  We express all the newforms of weight $2$ and levels $30$, $33$, $35$, $38$,
$40$, $42$, $44$, $45$ as linear combinations of eta quotients and Eisenstein
series, and list their corresponding strong Weil curves.
  Let $p$ denote a prime and $E (\zz_p)$ denote the the group of algebraic
points of an elliptic curve $E$ over $\zz_p$. We give a generating function for
the order of $E (\zz_p)$ for certain strong Weil curves in terms of eta
quotients and Eisenstein series. We then use our generating functions to deduce
congruence relations for the order of $E (\zz_p)$ for those strong Weil curves.


title: Relativistic polarizabilities with the Lagrange-mesh method

abstract:
  Relativistic dipolar to hexadecapolar polarizabilities of the ground state
and some excited states of hydrogenic atoms are calculated by using numerically
exact energies and wave functions obtained from the Dirac equation with the
Lagrange-mesh method. This approach is an approximate variational method taking
the form of equations on a grid because of the use of a Gauss quadrature
approximation. The partial polarizabilities conserving the absolute value of
the quantum number $\kappa$ are also numerically exact with small numbers of
mesh points. The ones where $|\kappa|$ changes are very accurate when using
three different meshes for the initial and final wave functions and for the
calculation of matrix elements. The polarizabilities of the $n=2$ excited
states of hydrogenic atoms are also studied with a separate treatment of the
final states that are degenerate at the nonrelativistic approximation. The
method provides high accuracies for polarizabilities of a particle in a Yukawa
potential and is applied to a hydrogen atom embedded in a Debye plasma.


title: Diphoton Signals from Colorless Hidden Quarkonia

abstract:
  We show that quarkonia-like states of a hidden SU(N) gauge group can account
for the 750 GeV diphoton excess observed by ATLAS and CMS, even with
constituents carrying standard model hypercharge only. The required hypercharge
is modest, varying between about 1.3-1.6 for strong SU(N) coupling, to 2-3 for
weak SU(N) coupling, for N=3, 4. This scenario predicts a variety of diphoton
and multi-photon resonances, as well as photons from continuum pair production,
and possibly exotic decays into standard model fermions, with no multi-jet
resonances.


title: Scotogenic model for co-bimaximal mixing

abstract:
  We present a scotogenic model, i.e. a one-loop neutrino mass model with dark
right-handed neutrino gauge singlets and one inert dark scalar gauge doublet
$\eta$, which has symmetries that lead to co-bimaximal mixing, i.e. to an
atmospheric mixing angle $\theta_{23} = 45^\circ$ and to a $CP$-violating phase
$\delta = \pm \pi/2$, while the mixing angle $\theta_{13}$ remains arbitrary.
The symmetries consist of softly broken lepton numbers $L_\alpha$ ($\alpha =
e,\mu,\tau$), a non-standard $CP$ symmetry, and three $Z_2$ symmetries. We
indicate two possibilities for extending the model to the quark sector. Since
the model has, besides $\eta$, three scalar gauge doublets, we perform a
thorough discussion of its scalar sector. We demonstrate that it can
accommodate a Standard Model-like scalar with mass $125\, \mathrm{GeV}$, with
all the other charged and neutral scalars having much higher masses.


title: Neighborhood approximations for non-linear voter models

abstract:
  Non-linear voter models assume that the opinion of an agent depends on the
opinions of its neighbors in a non-linear manner. This allows for voting rules
different from majority voting. While the linear voter model is known to reach
consensus, non-linear voter models can result in the coexistence of opposite
opinions. Our aim is to derive approximations to correctly predict the time
dependent dynamics, or at least the asymptotic outcome, of such local
interactions. Emphasis is on a probabilistic approach to decompose the opinion
distribution in a second-order neighborhood into lower-order probability
distributions. This is compared with an analytic pair approximation for the
expected value of the global fraction of opinions and a mean-field
approximation. Our reference case are averaged stochastic simulations of a
one-dimensional cellular automaton. We find that the probabilistic second-order
approach captures the dynamics of the reference case very well for different
non-linearities, i.e for both majority and minority voting rules, which only
partly holds for the first-order pair approximation and not at all for the
mean-field approximation. We further discuss the interesting phenomenon of a
correlated coexistence, characterized by the formation of large domains of
opinions that dominate for some time, but slowly change.


title:
Generalized negative flows in hierarchies of integrable evolution
  equations

abstract:
  A one-parameter generalization of the hierarchy of negative flows is
introduced for integrable hierarchies of evolution equations, which yields a
wider (new) class of non-evolutionary integrable nonlinear wave equations. As
main results, several integrability properties of these generalized negative
flow equation are established, including their symmetry structure, conservation
laws, and bi-Hamiltonian formulation. (The results also apply to the hierarchy
of ordinary negative flows). The first generalized negative flow equation is
worked out explicitly for each of the following integrable equations: Burgers,
Korteweg-de Vries, modified Korteweg-de Vries, Sawada-Kotera, Kaup-Kupershmidt,
Kupershmidt.


title:
Orbital reconstruction in nonpolar tetravalent transition-metal oxide
  layers

abstract:
  A promising route to tailoring the electronic properties of quantum materials
and devices rests on the idea of orbital engineering in multilayered oxide
heterostructures. Here we show that the interplay of interlayer charge
imbalance and ligand distortions provides a knob for tuning the sequence of
electronic levels even in intrinsically stacked oxides. We resolve in this
regard the $d$-level structure of layered Sr$_2$IrO$_4$ by electron spin
resonance. While canonical ligand-field theory predicts $g_{\parallel}$-factors
$\!<\!2$ for positive tetragonal distortions as present in Sr$_2$IrO$_4$, the
experiment indicates $g_{\parallel}\!>\!2$. This implies that the iridium $d$
levels are inverted with respect to their normal ordering. State-of-the-art
electronic-structure calculations confirm the level switching in Sr$_2$IrO$_4$,
whereas we find them in Ba$_2$IrO$_4$ to be instead normally ordered. Given the
nonpolar character of the metal-oxygen layers, our findings highlight the
tetravalent transition-metal 214 oxides as ideal platforms to explore
$d$-orbital reconstruction in the context of oxide electronics.


title:
The dynamics of publishing of posts and comments on facebook (the
  russian segment, the first five months of 2013)

abstract:
  The article presents a study of some characteristics of post and comment
publishing in the Russian segment of Facebook. A number of non-trivial results
has been obtained. For example, a significant anomaly has been detected in the
number of user accounts with the rate of publishing posts of approximately two
posts per three days. The analysis has been carried out at the level of basic
characteristics that are shared by most social media platforms. It makes
possible a direct comparison of obtained results with data from other
platforms. The article presents an approach to formalization and ordering of
structural and informational elements on social media platforms. The approach
is based on the representation of these structural elements in the form of a
coherent hierarchy of container objects and their relations. This method allows
to structure and analyze raw data from different social media platforms in a
unified algorithmic design. The described approach is more formal, universal
and constructive than other known approaches.


title:
Is the public sector of your country a diffusion borrower? Empirical
  evidence from Brazil

abstract:
  We propose a diffusion process to describe the global dynamic evolution of
credit operations at a national level given observed operations at a
subnational level in a sovereign country. Empirical analysis with a unique
dataset from Brazilian federate constituents supports the conclusions. Despite
the heterogeneity observed in credit operations at a subnational level, the
aggregated dynamics at a national level were accurately described with the
proposed model. Results may guide management of public finances, particularly
debt manager authorities in charge of reaching surplus targets.


title: Connectivity disruption sparks explosive epidemic spreading

abstract:
  We investigate the spread of an infection or other malfunction of cascading
nature when a system component can recover only if it remains reachable from a
functioning central component. We consider the susceptible-infected-susceptible
model, typical of mathematical epidemiology, on a network. Infection spreads
from infected to healthy nodes, with the addition that infected nodes can only
recover when they remain connected to a predefined central node, through a path
that contains only healthy nodes. In this system, clusters of infected nodes
will absorb their noninfected interior because no path exists between the
central node and encapsulated nodes. This gives rise to the simultaneous
infection of multiple nodes. Interestingly, the system converges to only one of
two stationary states: either the whole population is healthy or it becomes
completely infected. This simultaneous cluster infection can give rise to
discontinuous jumps of different sizes in the number of failed nodes. Larger
jumps emerge at lower infection rates. The network topology has an important
effect on the nature of the transition: we observed hysteresis for networks
with dominating local interactions. Our model shows how local spread can
abruptly turn uncontrollable when it disrupts connectivity at a larger spatial
scale.


title:
Observation of hard radiations in a laboratory atmospheric high-voltage
  discharge

abstract:
  The new results concerning neutron emission detection from a laboratory
high-voltage discharge in the air are presented. Data were obtained with a
combination of plastic scintillation detectors and $^3$He filled counters of
thermal neutrons. Strong dependence of the hard x-ray and neutron radiation
appearance on the field strength near electrodes, which is determined by their
form, was found. We have revealed a more sophisticated temporal structure of
the neutron bursts observed during of electric discharge. This may indicate
different mechanisms for generating penetrating radiation at the time formation
and development of the atmospheric discharge.


title:
Classical model of negative thermal expansion in solids with expanding
  bonds

abstract:
  We study negative thermal expansion (NTE) in model lattices with multiple
atoms per cell and first- and second-nearest neighbor interactions using the
(anharmonic) Morse potential. By exploring the phase space of neighbor
distances and thermal expansion rates of the bonds, we determine the conditions
under which NTE emerges. By permitting all bond lengths to expand at different
rates, we find that NTE is possible without appealing to fully rigid units.
Nearly constant, large-amplitude, isotropic NTE is observed up to the melting
temperature in a classical molecular dynamics model of a $\mathrm{ReO}_3$-like
structure when the rigidity of octahedral units is almost completely
eliminated. Only weak NTE, changing over to positive expansion is observed when
the corner-linked octahedra are rigid, with flexible second-neighbor bonds
between neighboring octahedra permitting easy rotation. We observe similar
changes to thermal expansion behavior for the diamond lattice: NTE when
second-neighbor interactions are weak to positive thermal expansion when
second-neighbor interactions are strong. From these observations, we suggest
that the only essential local conditions for NTE are atoms with low
coordination numbers along with very low energies for changing bond angles
relative to bond-stretching energies.


title: The Effect of Impurities on Striped Phases

abstract:
  We study the effect of algebraically localized impurities on striped phases
in one space-dimension. We therefore develop a functional-analytic framework
which allows us to cast the perturbation problem as a regular Fredholm problem
despite the presence of essential spectrum, caused by the soft translational
mode. Our results establish the selection of jumps in wavenumber and phase,
depending on the location of the impurity and the average wavenumber in the
system. We also show that, for select locations, the jump in the wavenumber
vanishes.


title: Moser's theorem on manifolds with corners

abstract:
  Moser's theorem (1965) states that the diffeomorphism group of a compact
manifold acts transitively on the space of all smooth positive densities with
fixed volume. Here we describe the extension of this result to manifolds with
corners. In particular we obtain Moser's theorem on simplices. The proof is
based on Banyaga's paper (1974), where Moser's theorem is proven for manifolds
with boundary. A cohomological interpretation of Banyaga's operator is given,
which allows a proof of Lefschetz duality using differential forms.


title: A Framework for Human Pose Estimation in Videos

abstract:
  In this paper, we present a method to estimate a sequence of human poses in
unconstrained videos. We aim to demonstrate that by using temporal information,
the human pose estimation results can be improved over image based pose
estimation methods. In contrast to the commonly employed graph optimization
formulation, which is NP-hard and needs approximate solutions, we formulate
this problem into a unified two stage tree-based optimization problem for which
an efficient and exact solution exists. Although the proposed method finds an
exact solution, it does not sacrifice the ability to model the spatial and
temporal constraints between body parts in the frames; in fact it models the
{\em symmetric} parts better than the existing methods. The proposed method is
based on two main ideas: `Abstraction' and `Association' to enforce the intra-
and inter-frame body part constraints without inducing extra computational
complexity to the polynomial time solution. Using the idea of `Abstraction', a
new concept of `abstract body part' is introduced to conceptually combine the
symmetric body parts and model them in the tree based body part structure.
Using the idea of `Association', the optimal tracklets are generated for each
abstract body part, in order to enforce the spatiotemporal constraints between
body parts in adjacent frames. A sequence of the best poses is inferred from
the abstract body part tracklets through the tree-based optimization. Finally,
the poses are refined by limb alignment and refinement schemes. We evaluated
the proposed method on three publicly available video based human pose
estimation datasets, and obtained dramatically improved performance compared to
the state-of-the-art methods.


title:
Frequency dependent dielectric properties of Al/ maleic anhydride (MA)
  /p-Si structures

abstract:
  Al/ maleic anhydride (MA) /p-Si organic Schottky devices were fabricated on a
p-Si semiconductor wafer by spin coating. The frequency and voltage dependent
dielectric constant of Al/MA/p-Si have been investigated. Dielectric properties
and electrical conductivity of contact structures have been investigated in
detail by using spectroscopic technique in a wide range of frequencies and
applied bias voltages at room temperature. The values of dielectric constant,
dielectric loss, dielectric loss tangent, real and imaginary parts of the
electrical modulus and ac electrical conductivity were found considerably
sensitive to frequency and applied bias voltage especially in depletion and
accumulation regions. Experimental results indicate that the values of
dielectric constant show a steep decrease with increasing frequency for each
voltage. The values of dielectric loss as a function of voltage show a jump,
and dielectric loss decreases with decreasing voltage and increasing frequency.
The weak increasing of the ac electrical conductivity on frequency is observed.
The real part of electric modulus increases with increasing frequency. Also,
the imaginary part of electric modulus shows a peak and the peak position
shifts to higher frequency with increasing applied voltage. It can be concluded
that the interfacial polarization can be more easily occurred at low
frequencies and the majority of interface states at metal semiconductor
interface contributes to deviation of dielectric properties of Al/MA/p-Si
structures.


title: Comet 322P/SOHO 1: An asteroid with the smallest perihelion distance?

abstract:
  We observed comet 322P/SOHO 1 (P/1999 R1) from the ground and with the
Spitzer Space Telescope when it was between 2.2 and 1.2 AU from the Sun. These
are the first observations of any SOHO-discovered periodic comet by a non-solar
observatory, and allow us to investigate its behavior under typical cometary
circumstances. 322P appeared inactive in all images. Its lightcurve suggests a
rotation period of 2.8+/-0.3 hr and has an amplitude greater than ~0.3 mag,
implying a density of at least 1000 kg m$^{-3}$, considerably higher than that
of any known comet. It has average colors of g'-r' = 0.52+/-0.04 and r'-i' =
0.04+/-0.09. We converted these to Johnson colors and found that the V-R color
is consistent with average cometary colors, but R-I is somewhat bluer; these
colors are most similar to V- and Q-type asteroids. Modeling of the optical and
IR photometry suggests it has a diameter of 150-320 m and a geometric albedo of
0.09-0.42, with diameter and albedo inversely related. Our upper limits to any
undetected coma are still consistent with a sublimation lifetime shorter than
the typical dynamical lifetimes for Jupiter Family Comets. These results
suggest that it may be of asteroidal origin and only active in the SOHO fields
of view via processes different from the volatile-driven activity of
traditional comets. If so, it has the smallest perihelion distance of any known
asteroid.


title: Computational aspects of rational residuosity

abstract:
  In this paper, we consider an extension of Jacobi's symbol, the so called
rational $2^k$-th power residue symbol. In Section 3, we prove a novel
generalization of Zolotarev's lemma. In Sections 4, 5 and 6, we show that
several hard computational problems are polynomial-time reducible to computing
these residue symbols, such as getting nontrivial information about factors of
semiprime numbers. We also derive criteria concerning the Quadratic Residuosity
Problem.


title:
Bloch waves in an arbitrary two-dimensional lattice of subwavelength
  Dirichlet scatterers

abstract:
  We study waves governed by the planar Helmholtz equation, propagating in an
infinite lattice of subwavelength Dirichlet scatterers, the periodicity being
comparable to the wavelength. Applying the method of matched asymptotic
expansions, the scatterers are effectively replaced by asymptotic point
constraints. The resulting coarse-grained Bloch-wave dispersion problem is
solved by a generalised Fourier series, whose singular asymptotics in the
vicinities of scatterers yield the dispersion relation governing modes that are
strongly perturbed from plane-wave solutions existing in the absence of the
scatterers; there are also empty-lattice waves that are only weakly perturbed.
Characterising the latter is useful in interpreting and potentially designing
the dispersion diagrams of such lattices. The method presented, that simplifies
and expands on Krynkin & McIver [Waves Random Complex, 19 347 2009], could be
applied in the future to study more sophisticated designs entailing resonant
subwavelength elements distributed over a lattice with periodicity on the order
of the operating wavelength.


title: EUV Irradiance Observations from SDO/EVE as a Diagnostic of Solar Flares

abstract:
  For the past six years, the EUV Variability Experiment (EVE) onboard the
Solar Dynamics Observatory has been monitoring changes in the Sun's extreme
ultraviolet output over a range of timescales. Its primary function is to
provide measurements of the solar spectral irradiance that is responsible for
driving fluctuations in Earth's ionosphere and thermosphere. However, despite
its modest spectral resolution and lack of spatial information, the EVE
spectral range contains many lines and continua that have become invaluable for
diagnosing the response of the lower solar atmosphere itself to an injection of
energy, particularly during a flare's impulsive phase. In addition, high
temperature emission lines can also be used to track changes in temperature and
density of flaring plasma in the corona. The high precision of EVE observations
are therefore crucial in helping us understand particle acceleration and energy
transport mechanisms during solar flares, as well as the origins of the Sun's
most geoeffective emission.


title: Euler Poincare Characteristic for the Oscillator Representation

abstract:
  Suppose $(G,G')$ is a dual pair of subgroups of a metaplectic group. The dual
pair correspondence is a bijection between (subsets of the) irreducible
representations of $G$ and $G'$, defined by the non-vanishing of
Hom$(\omega,\pi\times\pi')$, where $\omega$ is the oscillator representation.
Alternatively one considers Hom$_G(\omega,\pi)$ as a $G'$-module. It is
fruitful to replace Hom with Ext$^i$, and general considerations suggest that
the Euler-Poincare characteristic EP$(\omega,\pi)$, the alternating sum of
Ext$^i(\omega,\pi)$, will be a more elementary object. We restrict to the case
of $p$-adic groups, and prove that EP$(\omega,\pi)$ is a well defined element
of the Grothendieck group of finite length representations of $G'$, and show
that it is indeed more elementary than Hom$(\omega,\pi)$. We expect that
computation of EP, together with vanishing results for higher Ext groups, will
be a useful tool in computing the dual pair correspondence, and will help to
elucidate the structure of Hom$(\omega,\pi)$.


title:
Consequences of CCD imperfections for cosmology determined by weak
  lensing surveys: From laboratory measurements to cosmological parameter bias

abstract:
  Weak gravitational lensing causes subtle changes in the apparent shapes of
galaxies due to the bending of light by the gravity of foreground masses. By
measuring the shapes of large numbers of galaxies (millions in recent surveys,
up to tens of billions in future surveys) we can infer the parameters that
determine cosmology. Imperfections in the detectors used to record images of
the sky can introduce changes in the apparent shape of galaxies, which in turn
can bias the inferred cosmological parameters. In this paper we consider the
effect of two widely discussed sensor imperfections: tree-rings, due to
impurity gradients which cause transverse electric fields in the Charge-Coupled
Devices (CCD), and pixel-size variation, due to periodic CCD fabrication
errors. These imperfections can be observed when the detectors are subject to
uniform illumination (flat field images). We develop methods to determine the
spurious shear and convergence (due to the imperfections) from the flat-field
images. We calculate how the spurious shear when added to the lensing shear
will bias the determination of cosmological parameters. We apply our methods to
candidate sensors of the Large Synoptic Survey Telescope (LSST) as a timely and
important example, analyzing flat field images recorded with LSST prototype
CCDs in the laboratory. We find that tree-rings and periodic pixel-size
variation present in the LSST CCDs will introduce negligible bias to
cosmological parameters determined from the lensing power spectrum,
specifically w, {\Omega}m and {\sigma}8.


title: Scale Normalization

abstract:
  One of the difficulties of training deep neural networks is caused by
improper scaling between layers. Scaling issues introduce exploding / gradient
problems, and have typically been addressed by careful scale-preserving
initialization. We investigate the value of preserving scale, or isometry,
beyond the initial weights. We propose two methods of maintaing isometry, one
exact and one stochastic. Preliminary experiments show that for both
determinant and scale-normalization effectively speeds up learning. Results
suggest that isometry is important in the beginning of learning, and
maintaining it leads to faster learning.


title:
K-theory Classification of Graded Ultramatricial Algebras with
  Involution

abstract:
  We consider a generalization $K_0^{\operatorname{gr}}(R)$ of the standard
Grothendieck group $K_0(R)$ of a graded ring $R$ with involution. If $\Gamma$
is an abelian group, we show that $K_0^{\operatorname{gr}}$ completely
classifies graded ultramatricial $*$-algebras over a $\Gamma$-graded $*$-field
$A$ such that (1) each nontrivial graded component of $A$ has a unitary element
in which case we say that $A$ has enough unitaries, and (2) the zero-component
$A_0$ is 2-proper (for any $a,b\in A_0,$ $aa^*+bb^*=0$ implies $a=b=0$) and
$*$-pythagorean (for any $a,b\in A_0,$ $aa^*+bb^*=cc^*$ for some $c\in A_0$).
If the involutive structure is not considered, our result implies that
$K_0^{\operatorname{gr}}$ completely classifies graded ultramatricial algebras
over any graded field $A.$ If the grading is trivial and the involutive
structure is not considered, we obtain some well known results as corollaries.
  If $R$ and $S$ are graded matricial $*$-algebras over a $\Gamma$-graded
$*$-field $A$ with enough unitaries and $f: K_0^{\operatorname{gr}}(R)\to
K_0^{\operatorname{gr}}(S)$ is a contractive $\mathbb Z[\Gamma]$-module
homomorphism, we present a specific formula for a graded $*$-homomorphism
$\phi: R\to S$ with $K_0^{\operatorname{gr}}(\phi) = f.$ If the grading is
trivial and the involutive structure is not considered, our constructive proof
implies the known results with existential proofs.
  As an application of our results, we show that the graded version of the
Isomorphism Conjecture holds for a class of Leavitt path algebras: if $E$ and
$F$ are countable, row-finite, no-exit graphs in which every path ends in a
sink or a cycle and $K$ is a 2-proper and $*$-pythagorean field, then the
Leavitt path algebras $L_K(E)$ and $L_K(F)$ are isomorphic as graded rings if
any only if they are isomorphic as graded $*$-algebras.


title: A Sinusoidally-Architected Helicoidal Biocomposite

abstract:
  A fibrous herringbone-modified helicoidal architecture is identified within
the exocuticle of an impact-resistant crustacean appendage. This previously
unreported composite microstructure, which features highly textured apatite
mineral templated by an alpha-chitin matrix, provides enhanced stress
redistribution and energy absorption over the traditional helicoidal design
under compressive loading. Nanoscale toughening mechanisms are also identified
using high load nanoindentation and in-situ TEM picoindentation.


title:
The power of two: Assessing the impact of a second measurement of the
  weak-charge form factor of 208Pb

abstract:
  [Background] Besides its intrinsic value as a fundamental nuclear-structure
observable, the weak-charge density of 208Pb - a quantity that is closely
related to its neutron distribution - is of fundamental importance in
constraining the equation of state of neutron-rich matter.
  [Purpose] To assess the impact that a second electroweak measurement of the
weak-charge form factor of 208Pb may have on the determination of its overall
weak-charge density.
  [Methods] Using the two putative experimental values of the form factor,
together with a simple implementation of Bayes' theorem, we calibrate a
theoretically sound - yet surprisingly little known - symmetrized Fermi
function, that is characterized by a density and form factor that are both
known exactly in closed form.
  [Results] Using the charge form factor of 208Pb as a proxy for its
weak-charge form factor, we demonstrate that using only two experimental points
to calibrate the symmetrized Fermi function is sufficient to accurately
reproduce the experimental charge form factor over a significant range of
momentum transfers.
  [Conclusions] It is demonstrated that a second measurement of the weak-charge
form factor of 208Pb supplemented by a robust theoretical input in the form of
the symmetrized Fermi function, would place significant constraints on the
neutron distribution of 208Pb and, ultimately, on the equation of state of
neutron-rich matter.


title: The Systematic Normal Form of Lattices

abstract:
  We introduce a new canonical form of lattices called the systematic normal
form (SNF). We show that for every lattice there is an efficiently computable
"nearby" SNF lattice, such that for any lattice one can solve lattice problems
on its "nearby" SNF lattice, and translate the solutions back efficiently to
the original lattice. The SNF provides direct connections between arbitrary
lattices, and various lattice related problems like the
Shortest-Integer-Solution, Approximate Greatest Common Divisor. As our main
application of SNF we derive a new set of worst-to-average case lattice
reductions that deviate significantly from the template of Ajtai and improve
upon previous reductions in terms of simplicity.


title: Multiplicity one for certain paramodular forms of genus two

abstract:
  We show that certain paramodular cuspidal automorphic irreducible
representations of $\mathrm{GSp}(4,\mathbb{A}_\mathbb{Q})$, which are not CAP,
are globally generic. This implies a multiplicity one theorem for paramodular
cuspidal automorphic representations. Our proof relies on a reasonable
hypothesis concerning the non-vanishing of central values of automorphic
$L$-series.


title:
Electric polarization observed in single crystals of multiferroic
  Lu2MnCoO6

abstract:
  We report electric polarization and magnetization measurements in single
crystals of double perovskite Lu2MnCoO6 using pulsed magnetic fields and
optical second harmonic generation (SHG) in DC magnetic fields. we observe
well-resolved magnetic field-induced changes in the electric polarization in
single crystals and thereby resolve the question about whether multiferroic
behavior is intrinsic to these materials or an extrinsic feature of
polycrystals. We find electric polarization along the crystalline b-axis, that
is suppressed by applying a magnetic fields along c-axis and advance a model
for the origin of magnetoelectric coupling. We furthermore map the phase
diagram using both capacitance and electric polarization to identify regions of
ordering and regions of magnetoelectric hysteresis. This compound is a rare
example of coupled hysteretic behavior in the magnetic and electric properties.
The ferromagnetic-like magnetic hysteresis loop that couples to hysteretic
polarization can be attributed not to ordinary ferromagnetic domains, but to
the rich physics of magnetic frustration of Ising-like spins in the axial
next-nearest neighbor interaction model.


title: Programmable Crossbar Quantum-dot Cellular Automata Circuits

abstract:
  Quantum-dot fabrication and characterization is a well-established
technology, which is used in photonics, quantum optics and nanoelectronics.
Four quantum-dots placed at the corners of a square form a unit cell, which can
hold a bit of information and serve as a basis for Quantum-dot Cellular
Automata (QCA) nanoelectronic circuits. Although several basic QCA circuits
have been designed, fabricated and tested, proving that quantum-dots can form
functional, fast and low-power nanoelectornic circuits, QCA nanoelectronics
still remain at its infancy. One of the reasons for this is the lack of design
automation tools, which will facilitate the systematic design of large QCA
circuits that contemporary applications demand. Here we present novel,
programmable QCA circuits, which are based on crossbar architecture. These
circuits can be programmed to implement any Boolean function in analogy to CMOS
FPGAs and open the road that will lead to full design automation of QCA
nanoelectronic circuits. Using this architecture we designed and simulated QCA
circuits that proved to be area efficient, stable and reliable.


title: Compensation temperatures and exchange bias in La1.5Ca0.5CoIrO6

abstract:
  We report on the study of magnetic properties of the La1.5Ca0.5CoIrO6 double
perovskite. Via ac magnetic susceptibility we have observed evidence of weak
ferromagnetism and reentrant spin glass behavior on an antiferromagnetic
matrix. Regarding the magnetic behavior as a function of temperature, we have
found that the material displays up to three inversions of its magnetization,
depending on the appropriate choice of the applied magnetic field. At low
temperature the material exhibit exchange bias effect when it is cooled in the
presence of a magnetic field. Also, our results indicate that this effect may
be observed even when the system is cooled at zero field. Supported by other
measurements and also by electronic structure calculations, we discuss the
magnetic reversals and spontaneous exchange bias effect in terms of magnetic
phase separation and magnetic frustration of Ir4+ ions located between the
antiferromagnetically coupled Co ions.


title: Consistency in Distributed Data Stores

abstract:
  This paper focuses on the problem of consistency in distributed data
stores.We define strong consistency model which provides a simple semantics for
application programmers, but impossible to achieve with availability and
partition-tolerance. We also define weaker consistency models including causal
and eventual consistency. We review COPS and GentleRain as two causally
consistent data stores as well as Dynamo as an eventually consistent data
store. We provide insights about scenarios where each of these methods is
suitable, and some future research directions.


title:
Using Indirect Encoding of Multiple Brains to Produce Multimodal
  Behavior

abstract:
  An important challenge in neuroevolution is to evolve complex neural networks
with multiple modes of behavior. Indirect encodings can potentially answer this
challenge. Yet in practice, indirect encodings do not yield effective
multimodal controllers. Thus, this paper introduces novel multimodal extensions
to HyperNEAT, a popular indirect encoding. A previous multimodal HyperNEAT
approach called situational policy geometry assumes that multiple brains
benefit from being embedded within an explicit geometric space. However,
experiments here illustrate that this assumption unnecessarily constrains
evolution, resulting in lower performance. Specifically, this paper introduces
HyperNEAT extensions for evolving many brains without assuming geometric
relationships between them. The resulting Multi-Brain HyperNEAT can exploit
human-specified task divisions to decide when each brain controls the agent, or
can automatically discover when brains should be used, by means of preference
neurons. A further extension called module mutation allows evolution to
discover the number of brains, enabling multimodal behavior with even less
expert knowledge. Experiments in several multimodal domains highlight that
multi-brain approaches are more effective than HyperNEAT without multimodal
extensions, and show that brains without a geometric relation to each other
outperform situational policy geometry. The conclusion is that Multi-Brain
HyperNEAT provides several promising techniques for evolving complex multimodal
behavior.


title: An Enhanced Deep Feature Representation for Person Re-identification

abstract:
  Feature representation and metric learning are two critical components in
person re-identification models. In this paper, we focus on the feature
representation and claim that hand-crafted histogram features can be
complementary to Convolutional Neural Network (CNN) features. We propose a
novel feature extraction model called Feature Fusion Net (FFN) for pedestrian
image representation. In FFN, back propagation makes CNN features constrained
by the handcrafted features. Utilizing color histogram features (RGB, HSV,
YCbCr, Lab and YIQ) and texture features (multi-scale and multi-orientation
Gabor features), we get a new deep feature representation that is more
discriminative and compact. Experiments on three challenging datasets (VIPeR,
CUHK01, PRID450s) validates the effectiveness of our proposal.


title:
The Soft X-ray Spectrum of the High Mass X-Ray Binary V0332+53 in
  Quiescence

abstract:
  The propeller effect should cut off accretion in fast-spinning neutron star
high mass X-ray binaries (HMXBs) at low mass transfer rates. However, accretion
continues in some HMXBs at $L_{x} < 10^{34}$ erg s$^{-1}$, as evidenced by
continuing pulsations. Indications of spectral softening in systems in the
propeller regime suggest that some HMXBs are undergoing fundamental changes in
their accretion regime. A 39 ks \textit{XMM-Newton} observation of the
transient HMXB V0332+53 found it at a very low X-ray luminosity ($L_{x} \sim
4\times 10^{32}$ erg s${^{-1}}$). A power-law spectral fit requires an
unusually soft spectral index ($4.4^{+0.9}_{-0.6}$), while a magnetized neutron
star atmosphere model, with temperature \lt\ 6.7$\pm 0.2$ K and inferred
emitting radius of $\sim0.2-0.3$ km, gives a good fit. We suggest that the
quiescent X-ray emission from V0332+53 is mainly from a hot spot on the surface
of the neutron star. We could not detect pulsations from V0332+53, due to the
low count rate. Due to the high $N_H$, thermal emission from the rest of the
neutron star could be only weakly constrained, to \lt\
$<$6.14$^{+0.05}_{-6.14}$ K, or $<3\times10^{33}$ erg s${^{-1}}$.


title:
Entities as topic labels: Improving topic interpretability and
  evaluability combining Entity Linking and Labeled LDA

abstract:
  In order to create a corpus exploration method providing topics that are
easier to interpret than standard LDA topic models, here we propose combining
two techniques called Entity linking and Labeled LDA. Our method identifies in
an ontology a series of descriptive labels for each document in a corpus. Then
it generates a specific topic for each label. Having a direct relation between
topics and labels makes interpretation easier; using an ontology as background
knowledge limits label ambiguity. As our topics are described with a limited
number of clear-cut labels, they promote interpretability, and this may help
quantitative evaluation. We illustrate the potential of the approach by
applying it in order to define the most relevant topics addressed by each party
in the European Parliament's fifth mandate (1999-2004).


title: Bounding quantum gravity inspired decoherence using atom interferometry

abstract:
  Hypothetical models have been proposed in which explicit collapse mechanisms
prevent the superposition principle to hold at large scales. In particular, the
model introduced by Ellis and co-workers [Phys. Lett. B ${\bf 221}$, 113
(1989)] suggests that quantum gravity might be responsible for the collapse of
the wavefunction of massive objects in spatial superpositions. We here consider
a recent experiment reporting on interferometry with atoms delocalized over
half a meter for timescale of a second [Nature ${\bf 528}$, 530 (2015)] and
show that the corresponding data strongly bound quantum gravity induced
decoherence and rule it out in the parameter regime considered originally.


title: Counting SET-free sets

abstract:
  We consider the following counting problem related to the card game SET: How
many $k$-element SET-free sets are there in an $n$-dimensional SET deck?
Through a series of algebraic reformulations and reinterpretations, we show the
answer to this question satisfies two polynomiality conditions.


title: The role of the chemical potential in the BCS theory

abstract:
  We study the effect of the chemical potential on the results of the BCS
theory of superconductivity. We assume that the pairing interaction is
manifested between electrons of single-particle energies in an interval $[\mu -
\hbar\omega_c, \mu + \hbar\omega_c]$, where $\mu$ and $\omega_c$ are parameters
of the model--$\mu$ needs not be equal to the chemical potential of the system,
denoted here by $\mu_R$. The BCS results are recovered if $\mu = \mu_R$. If
$\mu \ne \mu_R$ the physical properties change significantly: the energy gap
$\Delta$ is smaller than the BCS gap, a population imbalance appears, and the
superconductor-normal metal phase transition is of the first order. The
quasiparticle imbalance is an equilibrium property that appears due to the
asymmetry with respect to $\mu_R$ of the single-particle energy interval in
which the pairing potential is manifested.
  For $\mu_R - \mu$ taking values in some ranges, the equation for $\Delta$ may
have more than one solution at the same temperature, forming branches of
solutions when $\Delta$ is plotted vs $\mu_R-\mu$ at fixed $T$. The solution
with the highest energy gap, which corresponds to the BCS solution when $\mu =
\mu_R$, cease to exist if $|\mu-\mu_R| \ge 2\Delta_0$ ($\Delta_0$ is the BCS
gap at zero temperature). Therefore the superconductivity is conditioned by the
existence of the pairing interaction and also by the value of $\mu_R - \mu$.


title: Finitely generated modules over quasi-Euclidean rings

abstract:
  Let R be a unital commutative ring and let $M$ be an $R$-module that is
generated by $k$ elements but not less. Let $E_n(R)$ be the subgroup of
$GL_n(R)$ generated by the elementary matrices. In this paper we study the
action of $E_n(R)$ by matrix multiplication on the set $Um_n(M)$ of unimodular
rows of $M$ of length $n \ge k$. Assuming $R$ is moreover Noetherian and
quasi-Euclidean, e.g., $R$ is a direct sum of finitely many Euclidean rings, we
show that this action is transitive if $n > k$. We also prove that $Um_k(M)
/E_k(R)$ is equipotent with the unit group of $R/(a_1)$ where $(a_1)$ is the
first invariant factor of $M$. These results encompass the well-known
classification of Nielsen non-equivalent generating tuples in finitely
generated Abelian groups.


title:
Regularized Jacobi iteration for decentralized convex optimization with
  separable constraints

abstract:
  We consider multi-agent, convex optimization programs subject to separable
constraints, where the constraint function of each agent involves only its
local decision vector, while the decision vectors of all agents are coupled via
a common objective function. We focus on a regularized variant of the so called
Jacobi algorithm for decentralized computation in such problems. We first
consider the case where the objective function is quadratic, and provide a
fixed-point theoretic analysis showing that the algorithm converges to a
minimizer of the centralized problem. Moreover, we quantify the potential
benefits of such an iterative scheme by comparing it against a scaled projected
gradient algorithm. We then consider the general case and show that all limit
points of the proposed iteration are optimal solutions of the centralized
problem. The efficacy of the proposed algorithm is illustrated by applying it
to the problem of optimal charging of electric vehicles, where, as opposed to
earlier approaches, we show convergence to an optimal charging scheme for a
finite, possibly large, number of vehicles.


title: Decay of near-critical currents in superconducting nanowires

abstract:
  We consider decay of supercurrent via phase slips in a discrete
one-dimensional superconductor (a chain of nodes connected by superconducting
links), aiming to explain the experimentally observed power-3/2 scaling of the
activation barrier in nanowires at currents close to the critical. We find
that, in this discrete model, the power-3/2 scaling holds for both long and
short wires even in the presence of bulk superconducting leads, despite the
suppression of thermal fluctuations at the ends. We also consider decay via
tunneling (quantum phase slips), which becomes important at low temperatures.
We find numerically the relevant Euclidean solutions (periodic instantons) and
determine the scaling of the tunneling exponent near the critical current. The
scaling law is power-5/4, different from that of the thermal activation
exponent.