title: A Semiparametric Model for Bayesian Reader Identification

abstract:
  We study the problem of identifying individuals based on their characteristic
gaze patterns during reading of arbitrary text. The motivation for this problem
is an unobtrusive biometric setting in which a user is observed during access
to a document, but no specific challenge protocol requiring the user's time and
attention is carried out. Existing models of individual differences in gaze
control during reading are either based on simple aggregate features of eye
movements, or rely on parametric density models to describe, for instance,
saccade amplitudes or word fixation durations. We develop flexible
semiparametric models of eye movements during reading in which densities are
inferred under a Gaussian process prior centered at a parametric distribution
family that is expected to approximate the true distribution well. An empirical
study on reading data from 251 individuals shows significant improvements over
the state of the art.


title:
The Orbit and Transit Prospects for $\beta$ Pictoris b constrained with
  One Milliarcsecond Astrometry

abstract:
  A principal scientific goal of the Gemini Planet Imager (GPI) is obtaining
milliarcsecond astrometry to constrain exoplanet orbits. However, astrometry of
directly imaged exoplanets is subject to biases, systematic errors, and speckle
noise. Here we describe an analytical procedure to forward model the signal of
an exoplanet that accounts for both the observing strategy (angular and
spectral differential imaging) and the data reduction method (Karhunen-Lo\`eve
Image Projection algorithm). We use this forward model to measure the position
of an exoplanet in a Bayesian framework employing Gaussian processes and Markov
chain Monte Carlo (MCMC) to account for correlated noise. In the case of GPI
data on $\beta$ Pic b, this technique, which we call Bayesian KLIP-FM
Astrometry (BKA), outperforms previous techniques and yields 1$\sigma$-errors
at or below the one milliarcsecond level. We validate BKA by fitting a
Keplerian orbit to twelve GPI observations along with previous astrometry from
other instruments. The statistical properties of the residuals confirm that BKA
is accurate and correctly estimates astrometric errors. Our constraints on the
orbit of $\beta$ Pic b firmly rule out the possibility of a transit of the
planet at 10-$\sigma$ significance. However, we confirm that the Hill sphere of
$\beta$ Pic b will transit, giving us a rare chance to probe the
circumplanetary environment of a young, evolving exoplanet. We provide an
ephemeris for photometric monitoring of the Hill sphere transit event, which
will begin at the start of April in 2017 and finish at the end of January in
2018.


title: Holographic heavy ion collisions with baryon charge

abstract:
  We numerically simulate collisions of charged shockwaves in Einstein-Maxwell
theory in anti-de Sitter space as a toy model of heavy ion collisions with
non-zero baryon charge. The stress tensor and the baryon current become well
described by charged hydrodynamics at roughly the same time. The effect of the
charge density on generic observables is typically no larger than 15\%. %The
rapidity profile of the charge is wider than the profile of the local energy
density. We find significant stopping of the baryon charge and compare our
results with those in heavy ion collision experiments.


title:
Feedback first: the surprisingly weak effects of magnetic fields,
  viscosity, conduction, and metal diffusion on galaxy formation

abstract:
  Using high-resolution simulations with explicit treatment of stellar feedback
physics based on the FIRE (Feedback in Realistic Environments) project, we
study how galaxy formation and the interstellar medium (ISM) are affected by
magnetic fields, anisotropic Spitzer-Braginskii conduction and viscosity, and
sub-grid metal diffusion from unresolved turbulence. We consider controlled
simulations of isolated (non-cosmological) galaxies but also a limited set of
cosmological "zoom-in" simulations. Although simulations have shown significant
effects from these physics with weak or absent stellar feedback, the effects
are much weaker than those of stellar feedback when the latter is modeled
explicitly. The additional physics have no systematic effect on galactic star
formation rates (SFRs) . In contrast, removing stellar feedback leads to SFRs
being over-predicted by factors of $\sim 10 -100$. Without feedback, neither
galactic winds nor volume filling hot-phase gas exist, and discs tend to
runaway collapse to ultra-thin scale-heights with unphysically dense clumps
congregating at the galactic center. With stellar feedback, a multi-phase,
turbulent medium with galactic fountains and winds is established. At currently
achievable resolutions and for the investigated halo mass range
$10^{10}-10^{13} M_{\odot}$, the additional physics investigated here (MHD,
conduction, viscosity, metal diffusion) have only weak ($\sim10\%$-level)
effects on regulating SFR and altering the balance of phases, outflows, or the
energy in ISM turbulence, consistent with simple equipartition arguments. We
conclude that galactic star formation and the ISM are primarily governed by a
combination of turbulence, gravitational instabilities, and feedback. We add
the caveat that AGN feedback is not included in the present work.


title:
Fractional quantum Hall states of dipolar fermions in a strained optical
  lattice

abstract:
  We study strongly correlated ground states of dipolar fermions in a honeycomb
optical lattice with spatial variations in hopping amplitudes. Similar to a
strained graphene, such nonuniform hopping amplitudes produce valley-dependent
pseudomagnetic fields for fermions near the two Dirac points, resulting in the
formation of Landau levels. The dipole moments polarized perpendicular to the
honeycomb plane yield a long-range repulsive interaction. By exact
diagonalization in the zeroth-Landau-level basis, we show that this repulsive
interaction stabilizes a variety of valley-polarized fractional quantum Hall
states such as Laughlin and composite-fermion states. The present system thus
offers an intriguing platform for emulating fractional quantum Hall physics in
a static optical lattice. We calculate the energy gaps above these
incompressible states, and discuss the temperature scales required for their
experimental realization.


title: Littlest Seesaw model from S4 x U(1)

abstract:
  We show how a minimal (littlest) seesaw model involving two right-handed
neutrinos and a very constrained Dirac mass matrix, with one texture zero and
two independent Dirac masses, may arise from $S_4\times U(1)$ symmetry in a
semi-direct supersymmetric model. The resulting CSD3 form of neutrino mass
matrix only depends on two real mass parameters plus one undetermined phase. We
show how the phase may be fixed to be one of the cube roots of unity by
extending the $S_4\times U(1)$ symmetry to include a product of $Z_3$ factors
together with a CP symmetry, which is spontaneously broken leaving a single
residual $Z_3$ in the charged lepton sector and a residual $Z_2$ in the
neutrino sector, with suppressed higher order corrections. With the phase
chosen from the cube roots of unity to be $-2\pi/3$, the model predicts a
normal neutrino mass hierarchy with $m_1=0$, reactor angle
$\theta_{13}=8.7^\circ$, solar angle $\theta_{12}=34^\circ$, atmospheric angle
$\theta_{23}=44^\circ$, and CP violating oscillation phase $\delta_{\rm
CP}=-93^\circ$, depending on the fit of the model to the neutrino masses.


title: Pre-thermal phases of matter protected by time-translation symmetry

abstract:
  In a periodically driven (Floquet) system, there is the possibility for new
phases of matter, not present in stationary systems, protected by discrete
time-translation symmetry. This includes topological phases protected in part
by time-translation symmetry, as well as phases distinguished by the
spontaneous breaking of this symmetry, dubbed "Floquet time crystals". We show
that such phases of matter can exist in the pre-thermal regime of
periodically-driven systems, which exists generically for sufficiently large
drive frequency, thereby eliminating the need for integrability or strong
quenched disorder that limited previous constructions. We prove a theorem that
states that such a pre-thermal regime persists until times that are nearly
exponentially-long in the ratio of certain couplings to the drive frequency. By
similar techniques, we can also construct stationary systems which
spontaneously break *continuous* time-translation symmetry. We argue
furthermore that for driven systems coupled to a cold bath, the pre-thermal
regime could potentially persist to infinite time.


title:
Dynamical piezoelectric and magnetopiezoelectric effects in polar metals
  from Berry phases and orbital moments

abstract:
  The polarization of a material and its response to applied electric and
magnetic fields are key solid-state properties with a long history in
insulators, although a satisfactory theory required new concepts such as
Berry-phase gauge fields. In metals, quantities such as static polarization and
magnetoelectric $\theta$-term cease to be well-defined. In polar metals there
can be analogous dynamical current responses, which we study in a common
theoretical framework. We find that current responses to dynamical strain in
polar metals depend on both the first and second Chern forms, related to
polarization and magnetoelectricity in insulators, as well as the orbital
magnetization on the Fermi surface. We provide realistic estimates that predict
that the latter contribution will dominate and investigate the feasibility of
experimental detection of this effect.


title: Spectrum of conformal gauge theories on a torus

abstract:
  Many model quantum spin systems have been proposed to realize critical points
or phases described by 2+1 dimensional conformal gauge theories. On a torus of
size $L$ and modular parameter $\tau$, the energy levels of such gauge theories
equal $(1/L)$ times universal functions of $\tau$. We compute the universal
spectrum of QED$_3$, a U(1) gauge theory with $N_f$ two-component massless
Dirac fermions, in the large $N_f$ limit. We also allow for a Chern-Simons term
at level $k$, and show how the topological $k$-fold ground state degeneracy in
the absence of fermions transforms into the universal spectrum in the presence
of fermions; these computations are performed at fixed $N_f/k$ in the large
$N_f$ limit.


title: Ingoing Eddington-Finkelstein Metric of an Evaporating Black Hole

abstract:
  We present an approximate time-dependent metric in ingoing
Eddington-Finkelstein coordinates for an evaporating nonrotating black hole as
a first-order perturbation of the Schwarzschild metric, using the linearized
back reaction from a realistic approximation to the stress-energy tensor for
the Hawking radiation in the Unruh quantum state.


title:
Sizing Up the Milky Way: A Bayesian Mixture Model Meta-Analysis of
  Photometric Scale Length Measurements

abstract:
  The exponential scale length ($L_d$) of the Milky Way's (MW's) disk is a
critical parameter for describing the global physical size of our Galaxy,
important both for interpreting other Galactic measurements and helping us to
understand how our Galaxy fits into extragalactic contexts. Unfortunately,
current estimates span a wide range of values and often are statistically
incompatible with one another. Here, we perform a Bayesian meta-analysis to
determine an improved, aggregate estimate for $L_d$, utilizing a mixture-model
approach to account for the possibility that any one measurement has not
properly accounted for all statistical or systematic errors. Within this
machinery we explore a variety of ways of modeling the nature of problematic
measurements, and then employ a Bayesian model averaging technique to derive
net posterior distributions that incorporate any model-selection uncertainty.
Our meta-analysis combines 29 different (15 visible and 14 infrared)
photometric measurements of $L_d$ available in the literature; these involve a
broad assortment of observational datasets, MW models and assumptions, and
methodologies, all tabulated herein. Analyzing the visible and infrared
measurements separately yields estimates for $L_d$ of $2.71^{+0.22}_{-0.20}$
kpc and $2.51^{+0.15}_{-0.13}$ kpc, respectively, whereas considering them all
combined yields $2.64\pm0.13$ kpc. The ratio between the visible and infrared
scale lengths determined here is very similar to that measured in external
spiral galaxies. We use these results to update the model of the Galactic disk
from our previous work, constraining its stellar mass to be
$4.8^{+1.5}_{-1.1}\times10^{10}$ $\textrm{M}_\odot$, and the MW's total stellar
mass to be $5.7^{+1.5}_{-1.1}\times10^{10}$ $\textrm{M}_\odot$.


title: Driven Topological Systems in the Classical Limit

abstract:
  Periodically-driven quantum systems can exhibit topologically non-trivial
behaviour, even when their quasi-energy bands have zero Chern numbers. Much
work has been conducted on non-interacting quantum-mechanical models where this
kind of behaviour is present. However, the inclusion of interactions in
out-of-equilibrium quantum systems can prove to be quite challenging. On the
other hand, the classical counterpart of hard-core interactions can be
simulated efficiently via constrained random walks. The non-interacting model
proposed by Rudner et al. [Phys. Rev. X 3, 031005 (2013)], has a special point
for which the system is equivalent to a classical random walk. We consider the
classical counterpart of this model, which is exact at a special point even
when hard-core interactions are present, and show how these quantitatively
affect the edge currents in a strip geometry. We find that the interacting
classical system is well described by a mean-field theory. Using this we
simulate the dynamics of the classical system, which show that the interactions
play the role of Markovian, or time dependent disorder. By comparing the
evolution of classical and quantum edge currents in small lattices, we find
regimes where the classical limit considered gives good insight into the
quantum problem.


title:
A Consistent Theory of Decaying Dark Matter Connecting IceCube to the
  Sesame Street

abstract:
  The high energy events observed at the IceCube Neutrino Observatory have
triggered many investigations interpreting the highly energetic neutrinos
detected as decay products of heavy unstable Dark Matter particles. However,
while very detailed treatments of the IceCube phenomenology exist, only a few
references focus on the (non-trivial) Dark Matter production part -- and all of
those rely on relatively complicated new models which are not always testable
directly. We instead investigate two of the most minimal scenarios possible,
where the operator responsible for the IceCube events is directly involved in
Dark Matter production. We show that the simplest (four-dimensional) operator
is not powerful enough to accommodate all constraints. A more non-minimal
setting (at mass dimension six), however, can do both fitting all the data and
also allowing for a comparatively small parameter space only, parts of which
can be in reach of future observations. We conclude that minimalistic
approaches can be enough to explain all data required, while complicated new
physics seems not to be required by IceCube.


title:
Relationship of EUV Irradiance Coronal Dimming Slope and Depth to
  Coronal Mass Ejection Speed and Mass

abstract:
  Extreme ultraviolet (EUV) coronal dimmings are often observed in response to
solar eruptive events. These phenomena can be generated via several different
physical processes. For space weather, the most important of these is the
temporary void left behind by a coronal mass ejection (CME). Massive, fast CMEs
tend to leave behind a darker void that also usually corresponds to minimum
irradiance for the cooler coronal emissions. If the dimming is associated with
a solar flare, as is often the case, the flare component of the irradiance
light curve in the cooler coronal emission can be isolated and removed using
simultaneous measurements of warmer coronal lines. We apply this technique to
37 dimming events identified during two separate two-week periods in 2011, plus
an event on 2010 August 7 analyzed in a previous paper, to parameterize dimming
in terms of depth and slope. We provide statistics on which combination of
wavelengths worked best for the flare-removal method, describe the fitting
methods applied to the dimming light curves, and compare the dimming parameters
with corresponding CME parameters of mass and speed. The best linear
relationships found are
  $$ \begin{align} v_{CME} \Big[\frac{km}{s} \Big] & \approx 2.36 \times 10^6
\Big[\frac{km}{\%} \Big] \times s_{dim} \Big[\frac{\%}{s} \Big] \\ m_{CME} [g]
& \approx 2.59 \times 10^{15} \Big[\frac{g}{\%} \Big] \times \sqrt{d_{dim}}
[\%]. \end{align} $$
  These relationships could be used for space weather operations of estimating
CME mass and speed using near-realtime irradiance dimming measurements.


title:
Schur complement inequalities for covariance matrices and monogamy of
  quantum correlations

abstract:
  We derive fundamental constraints for the Schur complement of positive
matrices, which provide an operator strengthening to recently established
information inequalities for quantum covariance matrices, including strong
subadditivity. This allows us to prove general results on the monogamy of
entanglement and steering quantifiers in continuous variable systems with an
arbitrary number of modes per party. A powerful hierarchical relation for
correlation measures based on the log-determinant of covariance matrices is
further established for all Gaussian states, which has no counterpart among
quantities based on the conventional von Neumann entropy.

categories: quant-ph cond-mat.stat-mech hep-th math-ph math.MP


title:
Near-infrared photometry and spectroscopy of the low Galactic latitude
  globular cluster 2MASS-GC03

abstract:
  We present deep near-infrared photometry and spectroscopy of the globular
cluster 2MASS-GC03 projected in the Galactic disk using MMIRS on the Clay
telescope (Las Campanas Observatory) and VISTA Variables in the Via Lactea
survey (VVV) data. Most probable cluster member candidates were identified from
near-infrared photometry. Out of ten candidates that were followed-up
spectroscopically, five have properties of cluster members, from which we
calculate <[Fe/H]> = -0.9 +- 0.2 and a radial velocity of v_r > = -78 +-
12km/s. A distance of 10.8kpc is estimated from 3 likely RRLyrae members. Given
that the cluster is currently at a distance of 4.2kpc from the Galactic center,
the cluster's long survival time of an estimated 11.3 +- 1.2Gyr strengthens the
case for its globular-cluster nature. The cluster has a hint of elongation in
the direction of the Galactic center.


title: Thermalization of particle detectors: The Unruh effect and its reverse

abstract:
  We study the Anti-Unruh effect in general stationary scenarios. We find that,
for accelerated trajectories, a particle detector coupled to a KMS state of a
quantum field can cool down (click less often) as the KMS temperature
increases. Remarkably, this is so even when the detector is switched on
adiabatically for infinitely long times. We also show that the Anti-Unruh
effect is characteristic of accelerated detectors, and cannot appear for
inertially moving detectors (e.g., in a thermal bath).


title:
Cosmology with intensity mapping techniques using atomic and molecular
  lines

abstract:
  We present a systematic study of the intensity mapping technique using
updated models for the different emission lines from galaxies and identify
which ones are more promising for cosmological studies of the post reionization
epoch. We consider the emission of ${\rm Ly\alpha}$, ${\rm H\alpha}$, H$\beta$,
optical and infrared oxygen lines, nitrogen lines, CII and the CO rotational
lines. We then identify that ${\rm Ly\alpha}$, ${\rm H\alpha}$, OII, CII and
the lowest rotational CO lines are the best candidates to be used as IM probes.
These lines form a complementary set of probes of the galaxies emission
spectra. We then use reasonable experimental setups from current, planned or
proposed experiments to access the detectability of the power spectrum of each
emission line. Intensity mapping of ${\rm Ly\alpha}$ emission from $z=2$ to 3
will be possible in the near future with HETDEX, while far-infrared lines
require new dedicated experiments. We also show that the proposed SPHEREx
satellite can use OII and ${\rm H\alpha}$ IM to study the large-scale
distribution of matter in intermediate redshifts of 1 to 4. We found that
submilimeter experiments with bolometers can have similar performances at
intermediate redshifts using CII and CO(3-2).


title:
Molecular and atomic gas along and across the main sequence of
  star-forming galaxies

abstract:
  We use spectra from the ALFALFA, GASS and COLD GASS surveys to quantify
variations in the mean atomic and molecular gas mass fractions throughout the
SFR-M* plane and along the main sequence (MS) of star-forming galaxies.
Although galaxies well below the MS tend to be undetected in the Arecibo and
IRAM observations, reliable mean atomic and molecular gas fractions can be
obtained through a spectral stacking technique. We find that the position of
galaxies in the SFR-M* plane can be explained mostly by their global cold gas
reservoirs as observed in the HI line, with in addition systematic variations
in the molecular-to-atomic ratio and star formation efficiency. When looking at
galaxies within +/-0.4 dex of the MS, we find that as stellar mass increases,
both atomic and molecular gas mass fractions decrease, stellar bulges become
more prominent, and the mean stellar ages increase. Both star formation
efficiency and molecular-to-atomic ratios vary little for massive main sequence
galaxies, indicating that the flattening of the MS is due to the global
decrease of the cold gas reservoirs of galaxies rather than to bottlenecks in
the process of converting cold atomic gas to stars.


title:
Production of the entire range of r-process nuclides by black hole
  accretion disc outflows from neutron star mergers

abstract:
  We consider $r$-process nucleosynthesis in outflows from black hole accretion
discs formed in double neutron star and neutron star -- black hole mergers.
These outflows, powered by angular momentum transport processes and nuclear
recombination, represent an important -- and in some cases dominant --
contribution to the total mass ejected by the merger. Here we calculate the
nucleosynthesis yields from disc outflows using thermodynamic trajectories from
hydrodynamic simulations, coupled to a nuclear reaction network. We find that
outflows produce a robust abundance pattern around the second $r$-process peak
(mass number $A \sim 130$), independent of model parameters, with significant
production of $A < 130$ nuclei. This implies that dynamical ejecta with high
electron fraction may not be required to explain the observed abundances of
$r$-process elements in metal poor stars. Disc outflows reach the third peak ($
A \sim 195$) in most of our simulations, although the amounts produced depend
sensitively on the disc viscosity, initial mass or entropy of the torus, and
nuclear physics inputs. Some of our models produce an abundance spike at $A =
132$ that is absent in the Solar system $r$-process distribution. The spike
arises from convection in the disc and depends on the treatment of nuclear
heating in the simulations. We conclude that disc outflows provide an important
-- and perhaps dominant -- contribution to the $r$-process yields of compact
binary mergers, and hence must be included when assessing the contribution of
these systems to the inventory of $r$-process elements in the Galaxy.


title:
Accurate predictions for charged Higgs production: closing the
  $m_{H^{\pm}}\sim m_t$ window

abstract:
  We present predictions for the total cross section for the production of a
charged Higgs boson in the intermediate-mass range ($m_{H^{\pm}}\sim m_t$) at
the LHC, focusing on a type-II two-Higgs-doublet model. Results are obtained at
next-to-leading order (NLO) accuracy in QCD perturbation theory, by studying
the full process $pp\to H^\pm W^\mp b \bar b$ in the complex-(top)-mass scheme
with massive bottom quarks. Compared to lowest-order predictions, NLO
corrections have a sizeable impact: they increase the cross section by roughly
50\% and reduce uncertainties due to scale variations by more than a factor of
two. Our computation reliably interpolates between the low- and high-mass
regime. Our results provide the first NLO prediction for charged Higgs
production in the intermediate-mass range and therefore allow to have NLO
accurate predictions in the full $m_{H^{\pm}}$ range. The extension of our
results to different realisations of the two-Higgs-doublet model or to the
supersymmetric case is also discussed.


title:
Discrimination of correlated and entangling quantum channels with
  selective process tomography

abstract:
  The accurate and reliable characterization of quantum dynamical processes
underlies efforts to validate quantum technologies, where discrimination
between competing models of observed behaviors inform efforts to fabricate and
operate qubit devices. We present a novel protocol for quantum channel
discrimination that leverages advances in direct characterization of quantum
dynamics (DCQD) codes. We demonstrate that DCQD codes enable selective process
tomography to improve discrimination between entangling and correlated quantum
dynamics. Numerical simulations show selective process tomography requires only
a few measurement configurations to achieve a low false alarm rate and that the
DCQD encoding improves the resilience of the protocol to hidden sources of
noise. Our results show that selective process tomography with DCQD codes is
useful for efficiently distinguishing sources of correlated crosstalk from
uncorrelated noise in current and future experimental platforms.


title:
Non-perturbative scalar potential inspired by type IIA strings on rigid
  CY

abstract:
  Motivated by a class of flux compactifications of type IIA strings on rigid
Calabi-Yau manifolds, preserving N=2 local supersymmetry in four dimensions, we
derive a non-perturbative potential of all scalar fields from the exact
D-instanton corrected metric on the hypermultiplet moduli space. Applying this
potential to moduli stabilization, we find a discrete set of exact vacua for
axions. At these critical points, the stability problem is decoupled into two
subspaces spanned by the axions and the other fields (dilaton and Kahler
moduli), respectively. Whereas the stability of the axions is easily achieved,
numerical analysis shows instabilities in the second subspace.


title:
Design of Feedback Control Laws for Information Transfer in Spintronics
  Networks

abstract:
  Information encoded in networks of stationary, interacting spin-1/2 particles
is central for many applications ranging from quantum spintronics to quantum
information processing. Without control, however, information transfer through
such networks is generally inefficient. Currently available control methods to
maximize the transfer fidelities and speeds mainly rely on dynamic control
using time-varying fields and often assume instantaneous readout. We present an
alternative approach to achieving efficient, high-fidelity transfer of
excitations by shaping the energy landscape via the design of time-invariant
feedback control laws without recourse to dynamic control. Both instantaneous
readout and the more realistic case of finite readout windows are considered.
The technique can also be used to freeze information by designing energy
landscapes that achieve Anderson localization. Perfect state or super-optimal
transfer and localization are enabled by conditions on the eigenstructure of
the system and signature properties for the eigenvectors. Given the
eigenstructure enabled by super-optimality, it is shown that feedback
controllers that achieve perfect state transfer are, surprisingly, also the
most robust with regard to uncertainties in the system and control parameters.


title: Unified Spin Model for Magnetic Excitations in Iron Chalcogenides

abstract:
  Recent inelastic neutron scattering (INS) measurements on FeSe and
Fe(Te$_{1-x}$Se$_x$), have sparked intense debate over the nature of the ground
state in these materials. Here we propose an effective bilinear-biquadratic
spin model which is shown to consistently describe the evolution of low-energy
spin excitations in FeSe, both under applied pressure and upon Se/Te
substitution. The phase diagram, studied using a combination of variational
mean-field, flavor-wave calculations, and density-matrix renormalization group
(DMRG), exhibits a sequence of transitions between the columnar antiferromagnet
common to the iron pnictides, the non-magnetic ferroquadrupolar phase
attributed to FeSe, and the double-stripe antiferromagnetic order known to
exist in Fe$_{1+y}$Te. The calculated spin structure factor in these phases
mimics closely that observed with INS in the Fe(Te$_{1-x}$Se$_x$), series. In
addition to the experimentally established phases, the possibility of
incommensurate magnetic order is also predicted.


title: Condensation-Driven Phase Transitions in Perturbed String Nets

abstract:
  We develop methods to probe the excitation spectrum of topological phases of
matter in two spatial dimensions. Applying these to the Fibonacci string nets
perturbed away from exact solvability, we analyze a topological phase
transition driven by the condensation of non-Abelian anyons. Our numerical
results illustrate how such phase transitions involve the spontaneous breaking
of a topological symmetry, generalizing the traditional Landau paradigm. The
main technical tool is the characterization of the ground states using tensor
networks and the topological properties using matrix-product-operator
symmetries. The topological phase transition manifests itself by symmetry
breaking in the entanglement degrees of freedom of the quantum transfer matrix.


title: The length of the low-redshift standard ruler

abstract:
  Assuming the existence of standard rulers, standard candles and standard
clocks, requiring only the cosmological principle, a metric theory of gravity,
a smooth expansion history, and using state-of-the-art observations, we
determine the length of the "low-redshift standard ruler". The data we use are
a compilation of recent Baryon acoustic oscillation data (relying on the
standard ruler), Type 1A supernov\ae\ (as standard candles), ages of early type
galaxies (as standard clocks) and local determinations of the Hubble constant
(as a local anchor of the cosmic distance scale). In a standard $\Lambda$CDM
cosmology the "low-redshift standard ruler" coincides with the sound horizon at
radiation drag, which can also be determined --in a model dependent way-- from
CMB observations. However, in general, the two quantities need not coincide. We
obtain constraints on the length of the low-redshift standard ruler: $r^h_{\rm
s}=101.0 \pm 2.3 h^{-1}$ Mpc, when using only Type 1A supernov\ae\ and Baryon
acoustic oscillations, and $r_{\rm s}=150.0\pm 4.7 $ Mpc when using clocks to
set the Hubble normalisation, while $r_{\rm s}=141.0\pm 5.5 $ Mpc when using
the local Hubble constant determination (using both yields $r_{\rm s}=143.9\pm
3.1 $ Mpc).
  The low-redshift determination of the standard ruler has an error which is
competitive with the model-dependent determination from cosmic microwave
background measurements made with the {\em Planck} satellite, which assumes it
is the sound horizon at the end of baryon drag.


title:
On the structure of formal balls of the balanced quasi-metric domain of
  words

abstract:
  In "Denotational semantics for programming languages, balanced quasi-metrics
and fixed points" (International Journal of Computer Mathematics 85 (2008),
623-630), J. Rodr\'{i}guez-L\'{o}pez, S. Romaguera and O. Valero introduced and
studied a balanced quasi-metric on any domain of (finite and infinite) words,
denoted by $q_{b}$. In this paper we show that the poset of formal balls
associated to $q_{b}$ has the structure of a continuous domain


title:
The Chemical Composition of the Galactic Bulge and Implications for its
  Evolution

abstract:
  The average bulge [Fe/H] and [Mg/H] are +0.06 and +0.17 dex, respectively, in
Baade's Window, roughly 0.2 dex higher than the thin disk and ~0.7 dex higher
than the local thick disk metallicity. This suggests a higher effective yield
in the bulge, perhaps due to more efficient retention of supernova ejecta. The
bulge vertical [Fe/H] gradient, at ~0.5 dex/kpc, appears to be due to a
changing mixture of sub-populations (near +0.3 dex and -0.3 dex and one
possibly near -0.7 dex) with latitude. The bulge is enhanced in O, Mg, Si, Ca,
Ti, and Al relative to the sun, with [alpha/Fe]=+0.15 dex at [Fe/H]=0.0 dex.
Below [Fe/H]~-0.5 dex, the bulge and local thick disk compositions are very
similar, but small [Mg/Fe] and possibly [<SiCaTi>/Fe] enhancements, low [La/Eu]
ratios and large [Cu/Fe], relative to the thick disk suggest slightly higher
SFR in the bulge. However, these composition differences could simply be due to
measurement errors and non-LTE effects. Unfortunately, comparison with the
thick disk near solar [Fe/H] suffers considerable confusion, due to poor
identification of the local thick disk. Unusual zig-zag abundance trends of
[Cu/Fe] and [Na/Fe] suggest nucleosynthesis dominated by core-collapse
supernovae with metallicity-dependent yields, in the Type~Ia supernova
time-delay scenario. Thus, the bulge sub-population compositions resemble the
local thin and thick disks, but at higher [Fe/H], suggesting a radial [Fe/H]
gradient in both the thin and thick disks, within the solar circle, near -0.04
to -0.05 dex/kpc. If the bulge was built through accretion of inner disk stars
by a bar, it appears that the inner thin and thick disk stars, incorporated
into the bulge, retained vertical scale heights characteristic of their
kinematic origin, and resulting in the vertical [Fe/H] gradient and [alpha/Fe]
trends seen today.


title: Einstein's Field Equations as a Fold Bifurcation

abstract:
  It is shown that Einstein's field equations for \emph{all} perfect-fluid
$k=0$ FLRW cosmologies have the same form as the topological normal form of a
fold bifurcation. In particular, we assume that the cosmological constant is a
bifurcation parameter, and as such, fold bifurcation behaviour is shown to
occur in a neighbourhood of Minkowski spacetime in the phase space. We show
that as this cosmological constant parameter is varied, an expanding and
contracting de Sitter universe \emph{emerge} via this bifurcation.


title:
Linear response of one-dimensional liquid $^4$He to external
  perturbations

abstract:
  We study the response of one-dimensional liquid $^4$He to weak perturbations
relying on the dynamical structure factor, $S(q,\omega)$, recently obtained via
ab-initio techniques [Phys. Rev. Lett. 116, 135302 (2016)]. We evaluate the
drag force, $F_v$, experienced by an impurity moving along the system with
velocity $v$ and the static response function, $\chi(q)$, describing the
density modulations induced by a periodic perturbation with wave vector $q$.


title: Environmental Information Improves Robotic Search Performance

abstract:
  We address the problem where a mobile search agent seeks to find an unknown
number of stationary objects distributed in a bounded search domain, and the
search mission is subject to time/distance constraint. Our work accounts for
false positives, false negatives and environmental uncertainty. We consider the
case that the performance of a search sensor is dependent on the environment
(e.g., clutter density), and therefore sensor performance is better in some
locations than in others. We specifically consider applications where
environmental information can be acquired either by a separate vehicle or by
the same vehicle that performs the search task. Our main contribution in this
study is to formally derive a decision-theoretic cost function to compute the
locations where the environmental information should be acquired. For the cases
where computing the optimal locations to sample the environment is
computationally expensive, we offer an approximation approach that yields
provable near-optimal paths. We show that our decision-theoretic cost function
outperforms the information-maximization approach, which is often employed in
similar applications.


title:
Associated production of a top pair and a W boson at
  next-to-next-to-leading logarithmic accuracy

abstract:
  We consider soft gluon emission corrections to the production of a
top-antitop pair in association with a W boson at the Large Hadron Collider. We
obtain a soft-gluon resummation formula for this production process which is
valid up to next-to-next-to-leading logarithmic accuracy. We evaluate the soft
gluon resummation formula in Mellin space by means of an in-house parton level
Monte Carlo code which allows us to obtain predictions for the total cross
section as well as for several differential distributions. We study the impact
of the soft-gluon resummation corrections in comparison to fixed order
calculations.


title:
A nonequilibrium diffusion and capture mechanism ensures
  tip-localization of regulating proteins on dynamic filaments

abstract:
  Diffusive motion of regulatory enzymes on biopolymers with eventual capture
at a reaction site is a common feature in cell biology. Using a lattice gas
model we study the impact of diffusion and capture for a microtubule polymerase
and a depolymerase. Our results show that the capture mechanism localizes the
proteins and creates large-scale spatial correlations. We develop an analytic
approximation that globally accounts for relevant correlations and yields
results that are in excellent agreement with experimental data. Our results
show that diffusion and capture operates most efficiently at cellular enzyme
concentrations which points to in vivo relevance.


title: Cusp Anomalous dimension and rotating open strings in AdS/CFT

abstract:
  In the context of AdS/CFT we provide analytical support for the proposed
duality between a Wilson loop with a cusp, the cusp anomalous dimension, and
the meson model constructed from a rotating open string with high angular
momentum. This duality was previously studied using numerical tools in [1]. Our
result implies that the minimum of the profile function of the minimal area
surface dual to the Wilson loop, is related to the inverse of the bulk
penetration of the dual string that hangs from the quark--anti-quark pair
(meson) in the gauge theory.


title:
Optical performance analysis of a porous open volumetric air receiver in
  a solar power tower

abstract:
  An optical model for a solar power tower with an open volumetric air receiver
(OVAR) was developed in this paper, and the optical performance and
characteristics of the OVAR were studied based on the model. Firstly, the
detailed distributions of the non-uniform solar flux (qsr) on the aperture and
the solar source (Ssr) in the OVAR were studied. The solar flux was found to be
relatively uniform across the aperture for a single OVAR. However the incident
angle of the rays varies between 0o and 42o, which indicates that the parallel
assumption of the rays is not appropriate at this condition. Furthermore, the
Ssr in the absorber decreases from the inlet to the outlet, and the maximum
source (Ssr,max) of 2.414X108 Wm-3 appears at the inlet. Moreover, the Ssr,max
was found to appear at the region near the wall rather than the center of the
receiver as usual for the combined effect of the non-parallel incident rays and
the diffuse reflection on the wall. In addition, study on effects of the porous
parameters indicates that the solid emissivity influences both the Ssr
distribution and the receiver efficiency significantly. However, the pore
diameter and the porosity influence Ssr distribution importantly, but have
negligible effect on the efficiency. Finally, the optical efficiency of 86.70%,
reflection loss of 13.20% and transmission loss of 0.10% were found to be
achieved by the OVAR.


title: Jumps, folds, and singularities of Kodaira moduli spaces

abstract:
  For any integer $k$ we construct an explicit example of a twistor space which
contains a one--parameter family of jumping rational curves, where the normal
bundle changes from $O(1)+O(1)$ to $O(k)+O(2-k)$. For $k>3$ the resulting
anti--self--dual Ricci-flat manifold is a Zariski cone in the space of
holomorphic sections of $O(k)$. In the case $k=2$ we recover the canonical
example of Hitchin's folded hyper-Kahler manifold, where the jumping lines form
a three--parameter family. We show that in this case there exist normalisable
solutions to the Schrodinger equation which extend through the fold.


title:
Microscopic study of static and dynamical properties of dilute
  one-dimensional soft bosons

abstract:
  We study static properties and the dynamical structure factor of
zero-temperature dilute bosons interacting via a soft-shoulder potential in one
dimension. Our approach is fully microscopic and employs state-of-the-art
quantum Monte Carlo and analytic continuation techniques. By increasing the
interaction strength, our model reproduces the Lieb-Liniger gas, the
Tonks-Girardeau and the Hard-Rods models.


title:
Revisiting the ground state of CoAl$_2$O$_4$: comparison to the
  conventional antiferromagnet MnAl$_2$O$_4$

abstract:
  The A-site spinel material, CoAl2O4, is a physical realization of the
frustrated diamond-lattice antiferromagnet, a model in which is predicted to
contain unique incommensurate or `spin-spiral liquid' ground states. Our
previous single-crystal neutron scattering study instead classified it as a
`kinetically-inhibited' antiferromagnet, where the long ranged correlations of
a collinear Neel ground state are blocked by the freezing of domain wall motion
below a first-order phase transition at T* = 6.5 K. The current paper expands
on our original results in several important ways. New elastic and inelastic
neutron measurements are presented that show our initial conclusions are
affected by neither the sample measured nor the instrument resolution, while
measurements to temperatures as low as T = 250 mK limit the possible role being
played by low-lying thermal excitations. Polarized diffuse neutron measurements
confirm reports of short-range antiferromagnetic correlations and diffuse
streaks of scattering, but major diffuse features are explained as signatures
of overlapping critical correlations between neighboring Brillouin zones.
Finally, and critically, this paper presents detailed elastic and inelastic
measurements of magnetic correlations in a single-crystal of MnAl2O4, which
acts as an unfrustrated analogue to CoAl2O4. The unfrustrated material is shown
to have a classical continuous phase transition to Neel order at T_N = 39 K,
with collective spinwave excitations and Lorentzian-like critical correlations
which diverge at the transition. Direct comparison between the two compounds
indicates that CoAl2O4 is unique, not in the nature of high-temperature diffuse
correlations, but rather in the nature of the frozen state below T*. The higher
level of cation inversion in the MnAl2O4 sample indicates that this novel
behavior is primarily an effect of greater next-nearest-neighbor exchange.


title: Quasi-invariant measures for some amenable groups acting on the line

abstract:
  In this note we show that if $G$ is a solvable group acting on the line, and
if there is $T\in G$ having no fixed points, then there is a Radon measure
$\mu$ on the line quasi-invariant under $G$. In fact, our method allows for the
same conclusion for $G$ inside a class of groups that is closed under
extensions and contains all solvable groups and all groups of subexponential
growth.


title:
Shape dependence of two-cylinder Renyi entropies for free bosons on a
  lattice

abstract:
  Universal scaling terms occurring in Renyi entanglement entropies have the
potential to bring new understanding to quantum critical points in free and
interacting systems. Quantitative comparisons between analytical continuum
theories and numerical calculations on lattice models play a crucial role in
advancing such studies. In this paper, we exactly calculate the universal
two-cylinder shape dependence of entanglement entropies for free bosons on
finite-size square lattices, and compare to approximate functions derived in
the continuum using several different ansatzes. Although none of these ansatzes
are exact in the thermodynamic limit, we find that numerical fits are in good
agreement with continuum functions derived using the AdS/CFT correspondence, an
extensive mutual information model, and a quantum Lifshitz model. We use fits
of our lattice data to these functions to calculate universal scalars defined
in the thin-cylinder limit, and compare to values previously obtained for the
free boson field theory in the continuum.


title:
A MegaCam Survey of Outer Halo Satellites. VI: The Spatially Resolved
  Star Formation History of the Carina Dwarf Spheroidal Galaxy

abstract:
  We present the spatially resolved star formation history (SFH) of the Carina
dwarf spheroidal galaxy, obtained from deep, wide-field g,r imaging and a
metallicity distribution from the literature. Our photometry covers $\sim2$
deg$^2$, reaching up to $\sim10$ times the half-light radius of Carina with a
completeness higher than $50\%$ at $g\sim24.5$, more than one magnitude fainter
than the oldest turnoff. This is the first time a combination of depth and
coverage of this quality has been used to derive the SFH of Carina, enabling us
to trace its different populations with unprecedented accuracy. We find that
Carina's SFH consists of two episodes well separated by a star formation
temporal gap. These episodes occurred at old ($>10$ Gyr) and intermediate
($2$-$8$ Gyr) ages. Our measurements show that the old episode comprises the
majority of the population, accounting for $54\pm5\%$ of the stellar mass
within $1.3$ times the King tidal radius, while the total stellar mass derived
for Carina is $1.60\pm0.09\times 10^{6} M_{\rm{\odot}}$, and the stellar
mass-to-light ratio $1.8\pm0.2$. The SFH derived is consistent with no recent
star formation which hints that the observed blue plume is due to blue
stragglers. We conclude that the SFH of Carina evolved independently of the
tidal field of the Milky Way, since the frequency and duration of its star
formation events do not correlate with its orbital parameters. This result is
supported by the age/metallicity relation observed in Carina, and the gradients
calculated indicating that outer regions are older and more metal poor.


title: Ocean swell within the kinetic equation for water waves

abstract:
  Effects of wave-wave interactions on ocean swell are studied. Results of
extensive simulations of swell evolution within the duration-limited setup for
the kinetic Hasselmann equation at long times up to $10^6$ seconds are
presented. Basic solutions of the theory of weak turbulence, the so-called
Kolmogorov-Zakharov solutions, are shown to be relevant to the results of the
simulations. Features of self-similarity of wave spectra are detailed and their
impact on methods of ocean swell monitoring are discussed. Essential drop of
wave energy (wave height) due to wave-wave interactions is found to be
pronounced at initial stages of swell evolution (of order of 1000 km for
typical parameters of the ocean swell). At longer times wave-wave interactions
are responsible for a universal angular distribution of wave spectra in a wide
range of initial conditions.


title: Evaluation of binomial double sums involving absolute values

abstract:
  We show that double sums of the form $$ \sum_{i,j=-n} ^{n}
|i^sj^t(i^k-j^k)^\beta| \binom {2n} {n+i} \binom {2n} {n+j} $$ can always be
expressed in terms of a linear combination of just four functions, namely
$\binom {4n}{2n}$, ${\binom {2n}n}^2$, $4^n\binom {2n}n$, and $16^n$, with
coefficients that are rational in $n$. We provide two different proofs: one is
algorithmic and uses the second author's computer algebra package Sigma; the
second is based on complex contour integrals. In many instances, these results
are extended to double sums of the above form where $\binom {2n}{n+j}$ is
replaced by $\binom {2m}{m+j}$ with independent parameter $m$.


title: Gravitational waves from pulsars with measured braking index

abstract:
  We study the putative emission of gravitational waves (GWs) in particular for
pulsars with measured braking index. We show that the appropriate combination
of both GW emission and magnetic dipole brakes can naturally explain the
measured braking index, when the surface magnetic field and the angle between
the magnetic dipole and rotation axes are time dependent. Then we discuss the
detectability of these very pulsars by aLIGO and the Einstein Telescope. We
call attention to the realistic possibility that aLIGO can detect the GWs
generated by at least some of these pulsars, such as Vela, for example.


title: Yukawa CFTs and Emergent Supersymmetry

abstract:
  We study conformal field theories with Yukawa interactions in dimensions
between 2 and 4; they provide UV completions of the Nambu-Jona-Lasinio and
Gross-Neveu models which have four-fermion interactions. We compute the sphere
free energy and certain operator scaling dimensions using dimensional
continuation. In the Gross-Neveu CFT with $N$ fermion degrees of freedom we
obtain the first few terms in the $4-\epsilon$ expansion using the
Gross-Neveu-Yukawa model, and the first few terms in the $2+\epsilon$ expansion
using the four-fermion interaction. We then apply Pade approximants to produce
estimates in $d=3$. For $N=1$, which corresponds to one 2-component Majorana
fermion, it has been suggested that the Yukawa theory flows to a ${\cal N}=1$
supersymmetric CFT. We provide new evidence that the $4-\epsilon$ expansion of
the $N=1$ Gross-Neveu-Yukawa model respects the supersymmetry. Our
extrapolations to $d=3$ appear to be in good agreement with the available
results obtained using the numerical conformal bootstrap. Continuation of this
CFT to $d=2$ provides evidence that the Yukawa theory flows to the tri-critical
Ising model. We apply a similar approach to calculate the sphere free energy
and operator scaling dimensions in the Nambu-Jona-Lasinio-Yukawa model, which
has an additional $U(1)$ global symmetry. For $N=2$, which corresponds to one
2-component Dirac fermion, this theory has an emergent supersymmetry with 4
supercharges, and we provide new evidence for this.


title: Continuous Time Quantum Walks in finite Dimensions

abstract:
  We consider the quantum search problem with a continuous time quantum walk
for networks of finite spectral dimension d_{s} of the network Laplacian. For
general networks of fractal (integer or non-integer) dimension d_{f}, for which
in general d_{f}\not=d_{s}, it suggests that d_{s} is the scaling exponent that
determines the computational complexity of the search. Our results are
consistent with those of Childs and Goldstone [Phys. Rev. A 70 (2004), 022314]
for lattices of integer dimension, where d=d_{f}=d_{s}. For general fractals,
we find that the Grover limit of quantum search can be obtained whenever
d_{s}>4. This complements the recent discussion of mean-field (i.e.,
d_{s}\to\infty) networks by Chakraborty et al. [Phys. Rev. Lett. 116 (2016),
100501] showing that for all those networks spatial search by quantum walk is
optimal.


title: Evolution of spherical over-densities in tachyon scalar field model

abstract:
  We study the tachyon scalar field model in flat FRW cosmology with the
particular potential $\phi^{-2}$ and the scale factor behavior $a(t)=t^n$. We
consider the spherical collapse model and investigate the effects of the
tachyon scalar field on the structure formation in flat FRW universe. We
calculate $\delta_{c}(z_{c})$, $\lambda(z_{c})$, $\xi(z_{c})$,
$\Delta_{V}(z_{c})$, $\log [\nu f(\nu)]$ and $\log [n(k)]$ for the tachyon
scalar field model and compare the results with the results of EdS model and
$\Lambda CDM$ model. It is shown that in the tachyon scalar field model the
structure formation may occur earlier, in comparison to the other models.


title:
Monte Carlo simulations of soft proton flares: testing the physics with
  XMM-Newton

abstract:
  Low energy protons (<100-300 keV) in the Van Allen belt and the outer regions
can enter the field of view of X-ray focusing telescopes, interact with the
Wolter-I optics, and reach the focal plane. The use of special filters protects
the XMM-Newton focal plane below an altitude of 70000 km, but above this limit
the effect of soft protons is still present in the form of sudden flares in the
count rate of the EPIC instruments, causing the loss of large amounts of
observing time. We try to characterize the input proton population and the
physics interaction by simulating, using the BoGEMMS framework, the proton
interaction with a simplified model of the X-ray mirror module and the focal
plane, and comparing the result with a real observation. The analysis of ten
orbits of observations of the EPIC/pn instrument show that the detection of
flares in regions far outside the radiation belt is largely influenced by the
different orientation of the Earth's magnetosphere respect with XMM-Newton's
orbit, confirming the solar origin of the soft proton population. The Equator-S
proton spectrum at 70000 km altitude is used for the proton population entering
the optics, where a combined multiple and Firsov scattering is used as physics
interaction. If the thick filter is used, the soft protons in the 30-70 keV
energy range are the main contributors to the simulated spectrum below 10 keV.
We are able to reproduce the proton vignetting observed in real data-sets, with
a 50\% decrease from the inner to the outer region, but a maximum flux of 0.01
counts cm-2 s-1 keV-1 is obtained below 10 keV, about 5 times lower than the
EPIC/MOS detection and 100 times lower than the EPIC/pn one. Given the high
variability of the flare intensity, we conclude that an average spectrum, based
on the analysis of a full season of soft proton events is required to compare
Monte Carlo simulations with real events.


title: Revisiting the nilpotent polynomial Hales-Jewett theorem

abstract:
  Answering a question posed by Bergelson and Leibman in [6], we establish a
nilpotent version of the polynomial Hales-Jewett theorem that contains the main
theorem in [6] as a special case. Important to the formulation and the proof of
our main theorem is the notion of a relative syndetic set (relative with
respect to a closed non-empty subsets of $\beta\mathbf{G}$) [25]. As a
corollary of our main theorem we prove an extension of the restricted van der
Waerden Theorem to nilpotent groups, which involves nilprogressions.


title:
Multistable switching dynamical system with the location of symmetric
  equilibria

abstract:
  A switching dynamical system by means of piecewise linear systems in R^3 that
presents multistability is presented. The flow of the system displays multiple
scroll attractors due to the unstable hyperbolic focus-saddle equilibria with
stability index of type I, i.e., a negative real eigenvalue and a pair of
complex conjugated eigenvalues with positive real part. This class of systems
is constructed by a discrete control mode changing the equilibrium point
regarding the location of their states. The scrolls are generated when the
stable and unstable eigenspaces of each adjacent equilibrium point generate the
stretching and folding mechanisms to generate chaos, i.e., the unstable
manifold in the first subsystem carry the trajectory towards the stable
manifold of the immediate adjacent subsystem.


title: Entropy as an adiabatic invariant

abstract:
  This short article was submitted to Nature Physics as a Correspondence. The
intention was to provide a brief albeit significant criticism of the work of J.
Dunkel and S. Hilbert, \textit{Consistent Thermostatistics Forbids Negative
Absolute Temperatures}, Nature Physics \textbf{10}, (2014). The respected
editor decided not to publish the Correspondence. We have therefore decided to
submit the paper to arXiv. Comments/criticisms are welcomed, particularly from
the authors of the mentioned paper.


title: Recursive construction of continuum random trees

abstract:
  We introduce a general recursive method to construct continuum random trees
(CRTs) from independent copies of a random string of beads, that is, any random
interval equipped with a random discrete probability measure, and from related
structures. We prove the existence of these CRTs as a new application of the
fixpoint method for recursive distribution equations formalised in high
generality by Aldous and Bandyopadhyay.
  We apply this recursive method to show the convergence to CRTs of various
tree growth processes. We note alternative constructions of existing
self-similar CRTs in the sense of Haas, Miermont and Stephenson, and we give
for the first time constructions of random compact R-trees that describe the
genealogies of Bertoin's self-similar growth fragmentations. In forthcoming
work, we develop further applications to embedding problems for CRTs, providing
a binary embedding of the stable line-breaking construction that solves an open
problem of Goldschmidt and Haas.


title: Dark matter inside early-type galaxies as function of mass and redshift

abstract:
  We study the behaviour of the dynamical and stellar mass inside the effective
radius (re) of early-type galaxies (ETGs). We use several samples of ETGs
-ranging from 19 000 to 98 000 objects- from the ninth data release of the
Sloan Digital Sky Survey. We consider Newtonian dynamics, different light
profiles and different Initial Mass Functions (IMF) to calculate the dynamical
and stellar mass. We assume that any difference between these two masses is due
to dark matter and/or a non Universal IMF. The main results for galaxies in the
redshift range 0.0024 < z < 0.3500 and in the dynamical mass range 9.5 < log(M)
< 12.5 are: i) A significant part of the intrinsic dispersion of the
distribution of dynamical vs. stellar mass is due to redshift. ii) The
difference between dynamical and stellar mass increases as a function of
dynamical mass and decreases as a function of redshift. iii) The difference
between dynamical and stellar mass goes from approximately 0% to 70% of the
dynamical mass depending on mass and redshift. iv) These differences could be
due to dark matter or a non Universal IMF or a combination of both. v) The
amount of dark matter inside ETGs would be equal to or less than the difference
between dynamical and stellar mass depending on the impact of the IMF on the
stellar mass estimation. vi) The previous results go in the same direction of
some results of the Fundamental Plane (FP) found in the literature in the sense
that they could be interpreted as an increase of dark matter along the FP and a
dependence of the FP on redshift.


title: Affine transformations of circle and sphere

abstract:
  A non-degenerate two-dimensional linear operator $\varphi$ transforms the
unit circle into ellipse. Let $p$ be the length of its bigger axis and $q$ --
the length of smaller. We can define the deformation coefficient $k(\varphi)$
as $q/p$. Analogously, if $\varphi$ is a non-degenerate three-dimensional
operator, then it transforms the unit sphere into ellipsoid. If $p>q>r$ are
lengths of its axes, then deformation coefficient $k(\varphi)$ will be defined
as $r/p$. In this work we compute the mean value of deformation coefficient in
two-dimensional case and give an estimation of mean value in three-dimensional
case.


title:
Robust Upward Dispersion of the Neutron Spin Resonance in the Heavy
  Fermion Superconductor Ce$_{1-x}$Yb$_{x}$CoIn$_5$

abstract:
  The neutron spin resonance is a collective magnetic excitation that appears
in copper oxide, iron pnictide, and heavy fermion unconventional
superconductors. Although the resonance is commonly associated with a
spin-exciton due to the $d$($s^{\pm}$)-wave symmetry of the superconducting
order parameter, it has also been proposed to be a magnon-like excitation
appearing in the superconducting state. Here we use inelastic neutron
scattering to demonstrate that the resonance in the heavy fermion
superconductor Ce$_{1-x}$Yb$_{x}$CoIn$_5$ with $x=0,0.05,0.3$ has a ring-like
upward dispersion that is robust against Yb-doping. By comparing our
experimental data with random phase approximation calculation using the
electronic structure and the momentum dependence of the $d_{x^2-y^2}$-wave
superconducting gap determined from scanning tunneling microscopy for
CeCoIn$_5$, we conclude the robust upward dispersing resonance mode in
Ce$_{1-x}$Yb$_{x}$CoIn$_5$ is inconsistent with the downward dispersion
predicted within the spin-exciton scenario.


title: Emotional Storytelling using Virtual and Robotic Agents

abstract:
  In order to create effective storytelling agents three fundamental questions
must be answered: first, is a physically embodied agent preferable to a virtual
agent or a voice-only narration? Second, does a human voice have an advantage
over a synthesised voice? Third, how should the emotional trajectory of the
different characters in a story be related to a storyteller's facial
expressions during storytelling time, and how does this correlate with the
apparent emotions on the faces of the listeners? The results of two specially
designed studies indicate that the physically embodied robot produces more
attention to the listener as compared to a virtual embodiment, that a human
voice is preferable over the current state of the art of text-to-speech, and
that there is a complex yet interesting relation between the emotion lines of
the story, the facial expressions of the narrating agent, and the emotions of
the listener, and that the empathising of the listener is evident through its
facial expressions. This work constitutes an important step towards emotional
storytelling robots that can observe their listeners and adapt their style in
order to maximise their effectiveness.


title:
Adiabatic regularisation of power spectra in nonminimally coupled
  chaotic inflation

abstract:
  We investigate the effect of adiabatic regularization on both the tensor- and
scalar-perturbation power spectra in \textit{nonminimally} coupled chaotic
inflation. Similar to that of the \textit{minimally} coupled general
single-field inflation, we find that the subtraction term is suppressed by an
exponentially decaying factor involving the number of $ e $-folds. By following
the subtraction term long enough beyond horizon crossing, the regularized power
spectrum tends to the "bare" power spectrum. This study justifies the use of
the unregularized ("bare") power spectrum in standard calculations.


title:
Systematic treatment of non-linear effects in Baryon Acoustic
  Oscillations

abstract:
  In this contribution we will discuss the non-linear effects in the baryon
acoustic oscillations and present a systematic and controllable way to account
for them within time-sliced perturbation theory.


title:
Higgs production in association with a top-antitop pair in the Standard
  Model Effective Field Theory at NLO in QCD

abstract:
  We present the results of the computation of the next-to-leading order QCD
corrections to the production cross section of a Higgs boson in association
with a top-antitop pair at the LHC, including the three relevant dimension-six
operators ($O_{t \varphi }, O_{\varphi G}, O_{tG}$) of the standard model
effective field theory. These operators also contribute to the production of
Higgs bosons in loop-induced processes at the LHC, such as inclusive Higgs,
$Hj$ and $HH$ production, and modify the Higgs decay branching ratios for which
we also provide predictions. We perform a detailed study of the cross sections
and their uncertainties at the total as well as differential level and of the
structure of the effective field theory at NLO including renormalisation group
effects. Finally, we show how the combination of information coming from
measurements of these production processes will allow to constrain the three
operators at the current and future LHC runs. Our results lead to a significant
improvement of the accuracy and precision of the deviations expected from
higher-dimensional operators in the SM in both the top-quark and the
Higgs-boson sectors and provide a necessary ingredient for performing a global
EFT fit to the LHC data at NLO accuracy.


title: Bright solitons in a PT-symmetric chain of dimers

abstract:
  We study the existence and stability of fundamental bright discrete solitons
in a parity-time (PT)-symmetric coupler composed by a chain of dimers, that is
modelled by linearly coupled discrete nonlinear Schrodinger equations with gain
and loss terms. We use a perturbation theory for small coupling between the
lattices to perform the analysis, which is then confirmed by numerical
calculations. Such analysis is based on the concept of the so-called
anti-continuum limit approach. We consider the fundamental onsite and intersite
bright solitons. Each solution has symmetric and antisymmetric configurations
between the arms. The stability of the solutions is then determined by solving
the corresponding eigenvalue problem. We obtain that both symmetric and
antisymmetric onsite mode can be stable for small coupling, on the contrary of
the reported continuum limit where the antisymmetric solutions are always
unstable. The instability is either due to the internal modes crossing the
origin or the appearance of a quartet of complex eigenvalues. In general, the
gain-loss term can be considered parasitic as it reduces the stability region
of the onsite solitons. Additionally, we analyse the dynamic behaviour of the
onsite and intersite solitons when unstable, where typically it is either in
the form of travelling solitons or soliton blow-ups.


title: Detecting Byzantine Attacks Without Clean Reference

abstract:
  We consider an amplify-and-forward relay network composed of a source, two
relays, and a destination. In this network, the two relays are untrusted in the
sense that they may perform Byzantine attacks by forwarding altered symbols to
the destination. Note that every symbol received by the destination may be
altered, and hence no clean reference observation is available to the
destination. For this network, we identify a large family of Byzantine attacks
that can be detected in the physical layer. We further investigate how the
channel conditions impact the detection against this family of attacks. In
particular, we prove that all Byzantine attacks in this family can be detected
with asymptotically small miss detection and false alarm probabilities by using
a sufficiently large number of channel observations \emph{if and only if} the
network satisfies a non-manipulability condition. No pre-shared secret or
secret transmission is needed for the detection of these attacks, demonstrating
the value of this physical-layer security technique for counteracting Byzantine
attacks.


title:
Critical behaviour and microscopic structure of charged AdS black holes
  via an alternative phase space

abstract:
  It has been argued that charged Ads black holes have similar thermodynamic
behavior as the Van der Waals fluid system, provided one treats the
cosmological constant as a thermodynamic variable in an extended phase space.
In this paper, we disclose the deep connection between charged AdS black holes
and Van der Waals fluid system without extending the phase space. We keep the
cosmological constant as a fixed parameter and instead, treat the square of the
charge of black hole as a thermodynamic variable. Therefore, we write the
equation of state as $Q^{2}=Q^{2}(T,\Psi)$ where $\Psi$ (conjugate of $Q^{2} $)
is the inverse of the specific volume, $\Psi=1/v$. This allows us to complete
the analogy of charged AdS black holes with Van der Waals fluid system and
derive the phase transition as well as critical exponents of the system. We
identify a thermodynamic instability in this new picture with real analogy to
Van der Waals fluid with physically relevant Maxwell construction. We therefore
study the critical behavior of isotherms in $% Q^2-\Psi$ diagram and deduce all
the critical exponents of the system and determine that the system exhibits a
small-large black hole phase transition at the critical point $(T_c,Q^2_c,
\Psi_c)$. This alternative view is important as one can imagine such a change
for a given single black hole i. e. acquiring charge which induces the phase
transition. Finally, we disclose the microscopic properties of charged AdS
black holes by using thermodynamic geometry. Interestingly, we find that scalar
curvature has a gap between small and large black holes, and this gap becomes
exceedingly large as one moves away from the critical point along the
transition line. Therefore, we are able to attribute the sudden enlargement of
the black hole to the strong repulsive nature of the internal constituents at
the phase transition.


title:
Learning to Allocate Limited Time to Decisions with Different Expected
  Outcomes

abstract:
  The goal of this article is to investigate how human participants allocate
their limited time to decisions with different properties. We report the
results of two behavioral experiments. In each trial of the experiments, the
participant must accumulate noisy information to make a decision. The
participants received positive and negative rewards for their correct and
incorrect decisions, respectively. The stimulus was designed such that
decisions based on more accumulated information were more accurate but took
longer. Therefore, the total outcome that a participant could achieve during
the limited experiments' time depended on her "decision threshold", the amount
of information she needed to make a decision. In the first experiment, two
types of trials were intermixed randomly: hard and easy. Crucially, the hard
trials were associated with smaller positive and negative rewards than the easy
trials. A cue presented at the beginning of each trial would indicate the type
of the upcoming trial. The optimal strategy was to adopt a small decision
threshold for hard trials. The results showed that several of the participants
did not learn this simple strategy. We then investigated how the participants
adjusted their decision threshold based on the feedback they received in each
trial. To this end, we developed and compared 10 computational models for
adjusting the decision threshold. The models differ in their assumptions on the
shape of the decision thresholds and the way the feedback is used to adjust the
decision thresholds. The results of Bayesian model comparison showed that a
model with time-varying thresholds whose parameters are updated by a
reinforcement learning algorithm is the most likely model.


title: Downlink MIMO HCNs with Residual Transceiver Hardware Impairments

abstract:
  A major limitation of heterogeneous cellular networks (HCNs) is the neglect
of the additive residual transceiver hardware impairments (ARTHIs). The
assumption of perfect hardware is quite strong and results in misleading
conclusions. This paper models a general multiple-input multiple-output (MIMO)
HCN with cell association by incorporating the RTHIs. We derive the coverage
probability and shed light on the impact of the ARTHIs, when various
transmission methods are applied. As the hardware quality decreases, the
coverage probability worsens. Especially, this effect is more severe as the
transmit power increases. Furthermore, we verify that in an HCN, it is better
to employ at each base station as few transmit antennas as possible.


title:
Fast Hyperspectral Unmixing in Presence of Nonlinearity or Mismodelling
  Effects

abstract:
  This paper presents two novel hyperspectral mixture models and associated
unmixing algorithms. The two models assume a linear mixing model corrupted by
an additive term whose expression can be adapted to account for multiple
scattering nonlinearities (NL), or mismodelling effects (ME). The NL model
generalizes bilinear models by taking into account higher order interaction
terms. The ME model accounts for different effects such as endmember
variability or the presence of outliers. The abundance and residual parameters
of these models are estimated by considering a convex formulation suitable for
fast estimation algorithms. This formulation accounts for constraints such as
the sum-to-one and non-negativity of the abundances, the non-negativity of the
nonlinearity coefficients, the spectral smoothness of the ME terms and the
spatial sparseness of the residuals. The resulting convex problem is solved
using the alternating direction method of multipliers (ADMM) whose convergence
is ensured theoretically. The proposed mixture models and their unmixing
algorithms are validated on both synthetic and real images showing competitive
results regarding the quality of the inference and the computational complexity
when compared to the state-of-the-art algorithms.


title: Positivity functions for curves on algebraic varieties

abstract:
  This is the second part of our work on Zariski decomposition structures,
where we compare two different volume type functions for curve classes. The
first function is the polar transform of the volume for ample divisor classes.
The second function captures the asymptotic geometry of curves analogously to
the volume function for divisors. We prove that the two functions coincide,
generalizing Zariski's classical result for surfaces to all varieties. Our
result confirms the log concavity conjecture of the first named author for
weighted mobility of curve classes in an unexpected way, via Legendre-Fenchel
type transforms. We also give a number of applications to birational geometry,
including a refined structure theorem for the movable cone of curves.


title: Geometry-Informed Material Recognition

abstract:
  Our goal is to recognize material categories using images and geometry
information. In many applications, such as construction management, coarse
geometry information is available. We investigate how 3D geometry (surface
normals, camera intrinsic and extrinsic parameters) can be used with 2D
features (texture and color) to improve material classification. We introduce a
new dataset, GeoMat, which is the first to provide both image and geometry data
in the form of: (i) training and testing patches that were extracted at
different scales and perspectives from real world examples of each material
category, and (ii) a large scale construction site scene that includes 160
images and over 800,000 hand labeled 3D points. Our results show that using 2D
and 3D features both jointly and independently to model materials improves
classification accuracy across multiple scales and viewing directions for both
material patches and images of a large scale construction site scene.


title:
Localization and instability in sheared granular materials: Role of
  friction and vibration

abstract:
  Shear banding and stick-slip instabilities have been long observed in sheared
granular materials. Yet, their microscopic underpinnings, interdependencies and
variability under different loading conditions have not been fully explored.
Here, we use a non-equilibrium thermodynamics model, the Shear Transformation
Zone theory, to investigate the dynamics of strain localization and its
connection to stability of sliding in sheared, dry, granular materials. We
consider frictional and frictionless grains as well as presence and absence of
acoustic vibrations. Our results suggest that at low and intermediate strain
rates, persistent shear bands develop only in the absence of vibrations.
Vibrations tend to fluidize the granular network and de-localize slip at these
rates. Stick-slip is only observed for frictional grains and it is confined to
the shear band. At high strain rates, stick-slip disappears and the different
systems exhibit similar stress-slip response. Changing the vibration intensity,
duration or time of application alters the system response and may cause
long-lasting rheological changes. We analyse these observations in terms of
possible transitions between rate strengthening and rate weakening response
facilitated by a competition between shear induced dilation and vibration
induced compaction. We discuss the implications of our results on dynamic
triggering, quiescence and strength evolution in gouge filled fault zones.


title: Synthesis and Applications of Birefringent Metasurfaces

abstract:
  Birefringent metasurfaces are two-dimensional structures capable of
independently controlling the amplitude, phase and polarization of orthogonally
polarized incident waves. In this work, we propose a in-depth discussion on the
mathematical synthesis of such metasurfaces. We compare two methods, one that
is rigorous and based on the exact electromagnetic fields involved in the
transformation and one that is based on approximate reflection and transmission
coefficients. We next validate the synthesis technique in metasurfaces
performing the operations of half- and quarter-wave plates, polarization beam
splitting and orbital angular momentum multiplexing.


title: A note on Itoh (e)-Valuation Rings of and Ideal

abstract:
  Let $I$ be a regular proper ideal in a Noetherian ring $R$, let $e \ge 2$ be
an integer, let $\mathbf T_e = R[u,tI,u^{\frac{1}{e}}]' \cap
R[u^{\frac{1}{e}},t^{\frac{1}{e}}]$ (where $t$ is an indeterminate and $u
=\frac{1}{t}$), and let $\mathbf r_e = u^{\frac{1}{e}} \mathbf T_e$. Then the
Itoh (e)-valuation rings of $I$ are the rings $(\mathbf T_e/z)_{(p/z)}$, where
$p$ varies over the (height one) associated prime ideals of $\mathbf r_e$ and
$z$ is the (unique) minimal prime ideal in $\mathbf T_e$ that is contained in
$p$. We show, among other things:
  (1) $\mathbf r_e$ is a radical ideal if and only if $e$ is a common multiple
of the Rees integers of $I$.
  (2) For each integer $k \ge 2$, there is a one-to-one correspondence between
the Itoh (k)-valuation rings $(V^*,N^*)$ of $I$ and the Rees valuation rings
$(W,Q)$ of $uR[u,tI]$; namely, if $F(u)$ is the quotient field of $W$, then
$V^*$ is the integral closure of $W$ in $F(u^{\frac{1}{k}})$.
  (3) For each integer $k \ge 2$, if $(V^*,N^*)$ and $(W,Q)$ are corresponding
valuation rings, as in (2), then $V^*$ is a finite integral extension domain of
$W$, and $W$ and $V^*$ satisfy the Fundamental Equality with no splitting.
Also, if $uW = Q^e$, and if the greatest common divisor of $e$ and $k$ is $d$,
and $c$ is the integer such that $cd = k$, then $QV^* = {N^*}^c$ and
$[(V^*/N^*):(W/Q)] = d$. Further, if $uW = Q^e$ and $k = qe$ is a multiple of
$e$, then there exists a unit $\theta_{e} \in V^*$ such that $V^* =
W[\theta_{e},u^{\frac{1}{k}}]$ is a finite free integral extension domain of
$W, QV^* = {N^*}^q, N^* = u^{\frac{1}{k}}V^*$, and $[V^*:W] = k$.
  (4) If the Rees integers of $I$ are all equal to $e$, then $V^* =
W[\theta_e]$ is a simple free integral extension domain of $W, QV^* = N^* =
u^{\frac{1}{e}}V^*$, and $[V^*:W] = e = [(V^*/N^*):(W/Q)]$.


title:
On the Optimality of Pseudo-polynomial Algorithms for Integer
  Programming

abstract:
  In the classic Integer Programming (IP) problem, the objective is to decide
whether, for a given $m \times n$ matrix $A$ and an $m$-vector $b=(b_1,\dots,
b_m)$, there is a non-negative integer $n$-vector $x$ such that $Ax=b$. Solving
(IP) is an important step in numerous algorithms and it is important to obtain
an understanding of the precise complexity of this problem as a function of
natural parameters of the input.
  The classic pseudo-polynomial time algorithm of Papadimitriou [J. ACM 1981]
for instances of (IP) with a constant number of constraints was only recently
improved upon by Eisenbrand and Weismantel [SODA 2018] and Jansen and Rohwedder
[ArXiv 2018]. We continue this line of work and show that under the Exponential
Time Hypothesis (ETH), the algorithm of Jansen and Rohwedder is nearly optimal.
We also show that when the matrix $A$ is assumed to be non-negative, a
component of Papadimitriou's original algorithm is already nearly optimal under
ETH.
  This motivates us to pick up the line of research initiated by Cunningham and
Geelen [IPCO 2007] who studied the complexity of solving (IP) with non-negative
matrices in which the number of constraints may be unbounded, but the
branch-width of the column-matroid corresponding to the constraint matrix is a
constant. We prove a lower bound on the complexity of solving (IP) for such
instances and obtain optimal results with respect to a closely related
parameter, path-width. Specifically, we prove matching upper and lower bounds
for (IP) when the path-width of the corresponding column-matroid is a constant.


title: Diagnosing shock temperature with NH$_3$ and H$_2$O profiles

abstract:
  In a previous study of the L1157 B1 shocked cavity, a comparison between
NH$_3$(1$_0$-$0_0$) and H$_2$O(1$_{\rm 10}$--1$_{\rm 01}$) transitions showed a
striking difference in the profiles, with H$_2$O emitting at definitely higher
velocities. This behaviour was explained as a result of the high-temperature
gas-phase chemistry occurring in the postshock gas in the B1 cavity of this
outflow. If the differences in behaviour between ammonia and water are indeed a
consequence of the high gas temperatures reached during the passage of a shock,
then one should find such differences to be ubiquitous among chemically rich
outflows. In order to determine whether the difference in profiles observed
between NH$_3$ and H$_2$O is unique to L1157 or a common characteristic of
chemically rich outflows, we have performed Herschel-HIFI observations of the
NH$_3$(1$_0$-0$_0$) line at 572.5 GHz in a sample of 8 bright low-mass outflow
spots already observed in the H$_2$O(1$_{\rm 10}$--1$_{\rm 01}$) line within
the WISH KP. We detected the ammonia emission at high-velocities at most of the
outflows positions. In all cases, the water emission reaches higher velocities
than NH$_3$, proving that this behaviour is not exclusive of the L1157-B1
position. Comparisons with a gas-grain chemical and shock model confirms, for
this larger sample, that the behaviour of ammonia is determined principally by
the temperature of the gas.


title:
Efficient and Modular Consensus-Free Reconfiguration for Fault-Tolerant
  Storage

abstract:
  Quorum systems are useful tools for implementing consistent and available
storage in the presence of failures. These systems usually comprise a static
set of servers that provide a fault-tolerant read/write register accessed by a
set of clients. We consider a dynamic variant of these systems and propose
FreeStore, a set of fault-tolerant protocols that emulates a register in
dynamic asynchronous systems in which processes are able to join/leave the
servers set during the execution. These protocols use a new abstraction called
view generators, that captures the agreement requirements of reconfiguration
and can be implemented in different system models with different properties.
Particularly interesting, we present a reconfiguration protocol that is
modular, efficient, consensus-free and loosely coupled with read/write
protocols, improving the overall system performance.


title:
Low-Complexity Recursive Convolutional Precoding for OFDM-based
  Large-Scale Antenna System

abstract:
  Large-scale antenna (LSA) has gained a lot of attention recently since it can
significantly improve the performance of wireless systems. Similar to
multiple-input multiple-output (MIMO) orthogonal frequency division
multiplexing (OFDM) or MIMO-OFDM, LSA can be also combined with OFDM to deal
with frequency selectivity in wireless channels. However, such combination
suffers from substantially increased complexity proportional to the number of
antennas in LSA systems. For the conventional implementation of LSA-OFDM, the
number of inverse fast Fourier transforms (IFFTs) increases with the antenna
number since each antenna requires an IFFT for OFDM modulation. Furthermore,
zero-forcing (ZF) precoding is required in LSA systems to support more users,
and the required matrix inversion leads to a huge computational burden. In this
paper, we propose a low-complexity recursive convolutional precoding to address
the issues above. The traditional ZF precoding can be implemented through the
recursive convolutional precoding in the time domain so that only one IFFT is
required for each user and the matrix inversion can be also avoided. Simulation
results show that the proposed approach can achieve the same performance as
that of ZF but with much lower complexity.


title: On Spaces of Topological Complexity Two

abstract:
  In this paper we consider the classification of minimal cellular structures
of spaces of topological complexity two under some hypotheses on there graded
cohomological algebra. This continues the method used by M.Grant et al. in [1].


title:
Critical Placements of a Square or Circle amidst Trajectories for
  Junction Detection

abstract:
  Motivated by automated junction recognition in tracking data, we study a
problem of placing a square or disc of fixed size in an arrangement of lines or
line segments in the plane. We let distances among the intersection points of
the lines and line segments with the square or circle define a clustering, and
study the complexity of \emph{critical} placements for this clustering. Here
critical means that arbitrarily small movements of the placement change the
clustering.
  A parameter $\varepsilon$ defines the granularity of the clustering. Without
any assumptions on $\varepsilon$, the critical placements have a trivial
$O(n^4)$ upper bound. When the square or circle has unit size and $0 <
\varepsilon < 1$ is given, we show a refined $O(n^2/\varepsilon^2)$ bound,
which is tight in the worst case.
  We use our combinatorial bounds to design efficient algorithms to compute
junctions. As a proof of concept for our algorithms we have a prototype
implementation that showcases their application in a basic visualization of a
set of $n$ trajectories and their $k$ most important junctions.


title:
Measurement of the second-order coherence function for metallic
  nanolasers

abstract:
  Due to the high spontaneous emission coupled into the resonance mode in
metallic nanolasers, there has been a debate concerning the coherence
properties of this family of light sources. The second-order coherence function
can unambiguously determine the nature of a given radiation. In this paper, an
approach to measure the second-order coherence function for broad linewidth
sources in the near-infrared telecommunication band is established based on a
modified Hanbury Brown and Twiss configuration. Using this set-up, it is shown
that metallic coaxial and disk-shaped nanolasers with InGaAsP multiple quantum
well gain systems are indeed capable of generating coherent radiation.


title: Magnetic Behavior of Superatom-Fullerene Assemblies

abstract:
  It has recently been possible to synthesize ordered assemblies composed of
magnetic superatomic clusters Ni9Te6(PEt3)8 separated by C60 and study their
magnetic behavior. We have carried out theoretical studies on model systems
consisting of magnetic superatoms separated by non-magnetic species to examine
the evolution in magnetic response as the nature of the magnetic superatom
(directions of spin quantization), the strength of isotropic and anisotropic
interactions, the magnetic anisotropy energy, and the size of the assembly are
varied. We have examined square planar configurations consisting 16, 24 and 48
sites with 8, 12 and 24 magnetic superatoms respectively. The magnetic atoms
are allowed 2 or 5 orientations. The model Hamiltonian includes isotropic
exchange interactions with second nearest neighbor ferromagnetic and nearest
neighbor antiferromagnetic couplings and anisotropic Dzyaloshinskii-Moriya
interactions. It is shown that the inclusion of Dzyaloshinskii-Moriya
interaction that cause spin canting is necessary to get qualitative response as
observed in experiments.


title: Lattices from tight equiangular frames

abstract:
  We consider the set of all linear combinations with integer coefficients of
the vectors of a unit tight equiangular $(k,n)$ frame and are interested in the
question whether this set is a lattice, that is, a discrete additive subgroup
of the $k$-dimensional Euclidean space. We show that this is not the case if
the cosine of the angle of the frame is irrational. We also prove that the set
is a lattice for $n = k+1$ and that there are infinitely many $k$ such that a
lattice emerges for $n = 2k$. We dispose of all cases in dimensions $k$ at most
$9$. In particular, we show that a $(7,28)$ frame generates a strongly eutactic
lattice and give an alternative proof of Roland Bacher's recent observation
that this lattice is perfect.


title:
Towards Analytics Aware Ontology Based Access to Static and Streaming
  Data (Extended Version)

abstract:
  Real-time analytics that requires integration and aggregation of
heterogeneous and distributed streaming and static data is a typical task in
many industrial scenarios such as diagnostics of turbines in Siemens. OBDA
approach has a great potential to facilitate such tasks; however, it has a
number of limitations in dealing with analytics that restrict its use in
important industrial applications. Based on our experience with Siemens, we
argue that in order to overcome those limitations OBDA should be extended and
become analytics, source, and cost aware. In this work we propose such an
extension. In particular, we propose an ontology, mapping, and query language
for OBDA, where aggregate and other analytical functions are first class
citizens. Moreover, we develop query optimisation techniques that allow to
efficiently process analytical tasks over static and streaming data. We
implement our approach in a system and evaluate our system with Siemens turbine
data.


title:
An Elementary Proof of Dodgson's Condensation Method for Calculating
  Determinants

abstract:
  In 1866, Charles Ludwidge Dodgson published a paper concerning a method for
evaluating determinants called the condensation method. His paper documented a
new method to calculate determinants that was based on Jacobi's Theorem. The
condensation method is presented and proven here, and is demonstrated by a
series of examples. The condensation method can be applied to a number of
situations, including calculating eigenvalues, solving a system of linear
equations, and even determining the different energy levels of a molecular
system. The method is much more efficient than cofactor expansions,
particularly for large matrices; for a 5 x 5 matrix, the condensation method
requires about half as many calculations. Zeros appearing in the interior of a
matrix can cause problems, but a way around the issue can usually be found.
Overall, Dodgson's condensation method is an interesting and simple way to find
determinants. This paper presents an elementary proof of Dodgson's method.


title:
Structured Models of Cell Migration Incorporating Molecular Binding
  Processes

abstract:
  The dynamic interplay between collective cell movement and the various
molecules involved in the accompanying cell signalling mechanisms plays a
crucial role in many biological processes including normal tissue development
and pathological scenarios such as wound healing and cancer. Information about
the various structures embedded within these processes allows a detailed
exploration of the binding of molecular species to cell-surface receptors
within the evolving cell population. In this paper we establish a general
spatio-temporal-structural framework that enables the description of molecular
binding to cell membranes coupled with the cell population dynamics. We first
provide a general theoretical description for this approach and then illustrate
it with two examples arising from cancer invasion.


title: How fear of future outcomes affects social dynamics

abstract:
  Mutualistic relationships among the different species are ubiquitous in
nature. To prevent mutualism from slipping into antagonism, a host often
invokes a "carrot and stick" approach towards symbionts with a stabilizing
effect on their symbiosis. In open human societies, a mutualistic relationship
arises when a native insider population attracts outsiders with benevolent
incentives in hope that the additional labor will improve the standard of all.
A lingering question, however, is the extent to which insiders are willing to
tolerate outsiders before mutualism slips into antagonism. To test the
assertion by Karl Popper that unlimited tolerance leads to the demise of
tolerance, we model a society under a growing incursion from the outside.
Guided by their traditions of maintaining the social fabric and prizing
tolerance, the insiders reduce their benevolence toward the growing
subpopulation of outsiders but do not invoke punishment. This reduction of
benevolence intensifies as less tolerant insiders (e.g., "radicals") openly
renounce benevolence. Although more tolerant insiders maintain some level of
benevolence, they may also tacitly support radicals out of fear for the future.
If radicals and their tacit supporters achieve a critical majority, herd
behavior ensues and the relation between the insider and outsider
subpopulations turns antagonistic. To control the risk of unwanted social
dynamics, we map the parameter space within which the tolerance of insiders is
in balance with the assimilation of outsiders, the tolerant insiders maintain a
sustainable majority, and any reduction in benevolence occurs smoothly. We also
identify the circumstances that cause the relations between insiders and
outsiders to collapse or that lead to the dominance of the outsiders.


title: Logistics of Mathematical Modeling-Focused Projects

abstract:
  This article addresses the logistics of implementing projects in an
undergraduate mathematics class and is intended both for new instructors and
for instructors who have had negative experiences implementing projects in the
past. Project implementation is given for both lower and upper division
mathematics courses with an emphasis on mathematical modeling and data
collection. Projects provide tangible connections to course content which can
motivate students to learn at a deeper level. Logistical pitfalls and insights
are highlighted as well as descriptions of several key implementation
resources. Effective assessment tools, which allowed me to smoothly adjust to
student feedback, are demonstrated for a sample class. As I smoothed the
transition into each project and guided students through the use of the
technology, their negative feedback on projects decreased and more students
noted how the projects had enhanced their understanding of the course topics.
Best practices learned over the years are given along with project summaries
and sample topics. These projects were implemented at a small liberal arts
university, but advice is given to extend them to larger classes for broader
use.


title: How to Emulate Web Traffic Using Standard Load Testing Tools

abstract:
  Conventional load-testing tools are based on a fifty-year old time-share
computer paradigm where a finite number of users submit requests and respond in
a synchronized fashion. Conversely, modern web traffic is essentially
asynchronous and driven by an unknown number of users. This difference presents
a conundrum for testing the performance of modern web applications. Even when
the difference is recognized, performance engineers often introduce
modifications to their test scripts based on folklore or hearsay published in
various Internet fora, much of which can lead to wrong results. We present a
coherent methodology, based on two fundamental principles, for emulating web
traffic using a standard load-test environment.


title:
Boundary bubbling analysis of approximate harmonic maps under either
  weak or strong anchoring conditions in dimension two

abstract:
  In this paper, we will study the bubbling phenomena of approximate harmonic
maps in dimension two that have either (i) bounded $L^2$-tension fields under
the weak anchoring condition, or (ii) bounded $L\log L \cap
M^{1,\delta}$-tension fields under the strong anchoring condition.


title:
Singular dynamics and emergence of nonlocality in long-range quantum
  models

abstract:
  We discuss how nonlocality originates in long-range quantum systems and how
it affects their dynamics at and out of the equilibrium. We focus in particular
on the Kitaev chains with long-range pairings and on the quantum Ising chain
with long-range antiferromagnetic coupling (both having a power-law decay with
exponent \alpha). By studying the dynamic correlation functions, we find that
for every finite \alpha two different behaviours can be identified, one typical
of short-range systems and the other connected with locality violation. The
latter behaviour is shown related also with the known power-law decay tails
previously observed in the static correlation functions, and originated by
modes, having in general energies far from the minima of the spectrum, where
particular singularities develop as a consequence of the long-rangedness of the
system. We refer to these modes as to "singular" modes, and as to "singular
dynamics" to their dynamics. For the Kitaev model they are manifest, at finite
\alpha, in derivatives of the quasiparticle energy, the order of the derivative
at which the singularity occurs increasing with \alpha. The features of the
singular modes and their physical consequences are clarified by studying an
effective theory for them and by a critical comparison of the results from this
theory with the lattice ones. Moreover, a numerical study of the effects of the
singular modes on the time evolution after various types of global quenches is
performed. We finally present and discuss the presence of singular modes and
their consequences in interacting long-range systems by investigating in the
long-range Ising quantum chain, both in the deep paramagnetic regime and at
criticality, where they also play a central role for the breakdown of conformal
invariance.

categories: cond-mat.str-el cond-mat.quant-gas cond-mat.stat-mech hep-th quant-ph