title: Chaos in AdS$_2$ holography

abstract:
  We revisit AdS$_2$ holography with the Sachdev-Ye-Kitaev models in mind. Our
main result is to rewrite a generic theory of gravity near an AdS$_2$ throat as
a novel hydrodynamics coupled to the correlation functions of a conformal
quantum mechanics. This gives a prescription for the computation of $n$-point
functions in the dual quantum mechanics. We thereby find that the dual is
maximally chaotic.


title:
The Asymptotic Number of Simple Singular Vector Tuples of a Cubical
  Tensor

abstract:
  S. Ekhad and D. Zeilberger recently proved that the multivariate generating
function for the number of simple singular vector tuples of a generic $m_1
\times \cdots \times m_d$ tensor has an elegant rational form involving
elementary symmetric functions, and provided a partial conjecture for the
asymptotic behavior of the cubical case $m_1 = \cdots = m_d$. We prove this
conjecture and further identify completely the dominant asymptotic term,
including the multiplicative constant. Finally, we use the method of
differential approximants to conjecture that the subdominant connective
constant effect observed by Ekhad and Zeilberger for a particular case in fact
occurs more generally.


title: High-temperature asymptotics of the 4d superconformal index

abstract:
  The superconformal index of a typical Lagrangian 4d SCFT is given by a
special function known as an elliptic hypergeometric integral (EHI). The
high-temperature limit of the index corresponds to the hyperbolic limit of the
EHI. The hyperbolic limit of certain special EHIs has been analyzed by Eric
Rains around 2006; extending Rains's techniques, we discover a surprisingly
rich structure in the high-temperature limit of a (rather large) class of EHIs
that arise as the superconformal index of unitary Lagrangian 4d SCFTs with
non-chiral matter content. Our result has implications for $\mathcal{N}=1$
dualities, the AdS/CFT correspondence, and supersymmetric gauge dynamics on
$R^3\times S^1$.
  We also investigate the high-temperature asymptotics of the large-N limit of
the superconformal index of a class of holographic 4d SCFTs (described by toric
quiver gauge theories with SU(N) nodes). We show that from this study a rather
general solution to the problem of holographic Weyl anomaly in AdS$_5$/CFT$_4$
at the subleading order (in the 1/N expansion) emerges.
  Most of this dissertation is based on published works by Jim Liu, Phil
Szepietowski, and the author. We include here a few previously unpublished
results as well, one of which is the high-temperature asymptotics of the
superconformal index of puncture-less SU(2) class-$\mathcal{S}$ theories.


title:
The SLUGGS Survey: The mass distribution in early-type galaxies within
  five effective radii and beyond

abstract:
  We study mass distributions within and beyond 5~effective radii ($R_{\rm e}$)
in 23 early-type galaxies from the SLUGGS survey, using their globular cluster
(GC) kinematic data. The data are obtained with Keck/DEIMOS spectrograph, and
consist of line-of-sight velocities for ~$3500$ GCs, measured with a high
precision of ~15 $\rm km\ s^{-1}$ per GC and extending out to $~13 R_{\rm e}$.
We obtain the mass distribution in each galaxy using the tracer mass estimator
of Watkins et al. and account for kinematic substructures, rotation of the GC
systems and galaxy flattening in our mass estimates.
  The observed scatter between our mass estimates and results from the
literature is less than 0.2 dex. The dark matter fraction within $5R_{\rm e}$
($f_{\rm DM}$) increases from ~$0.6$ to ~$0.8$ for low- and high-mass galaxies,
respectively, with some intermediate-mass galaxies ($M_*{\sim}10^{11}M_\odot$)
having low $f_{\rm DM}\sim0.3$, which appears at odds with predictions from
simple galaxy models. We show that these results are independent of the adopted
orbital anisotropy, stellar mass-to-light ratio, and the assumed slope of the
gravitational potential. However, the low $f_{\rm DM}$ in the ~$10^{11}M_\odot$
galaxies agrees with the cosmological simulations of Wu et al. where the
pristine dark matter distribution has been modified by baryons during the
galaxy assembly process. We find hints that these $M_*\sim10^{11}M_\odot$
galaxies with low $f_{\rm DM}$ have very diffuse dark matter haloes, implying
that they assembled late. Beyond $5R_{\rm e}$, the $M/L$ gradients are steeper
in the more massive galaxies and shallower in both low and intermediate mass
galaxies.


title: hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System

abstract:
  We present the public version of hi_class (www.hiclass-code.net), an
extension of the Boltzmann code CLASS to a broad ensemble of modifications to
general relativity. In particular, hi_class can calculate predictions for
models based on Horndeski's theory, which is the most general scalar-tensor
theory described by second-order equations of motion and encompasses any
perfect-fluid dark energy, quintessence, Brans-Dicke, $f(R)$ and covariant
Galileon models. hi_class has been thoroughly tested and can be readily used to
understand the impact of alternative theories of gravity on linear structure
formation as well as for cosmological parameter extraction.


title: Observation of $\pi^- K^+$ and $\pi^+ K^-$ atoms

abstract:
  The observation of hydrogen-like $\pi K$ atoms, consisting of $\pi^- K^+$ or
$\pi^+ K^-$ mesons, is presented. The atoms have been produced by 24 GeV/$c$
protons from the CERN PS accelerator, interacting with platinum or nickel foil
targets. The breakup (ionisation) of $\pi K$ atoms in the same targets yields
characteristic $\pi K$ pairs, called "atomic pairs", with small relative
momenta in the pair centre-of-mass system. The upgraded DIRAC experiment has
observed $349\pm62$ such atomic $\pi K$ pairs, corresponding to a signal of 5.6
standard deviations.


title:
Running vacuum in the Universe and the time variation of the fundamental
  constants of Nature

abstract:
  We compute the time variation of the fundamental constants (such as the ratio
of the proton mass to the electron mass, the strong coupling constant, the fine
structure constant and Newton's constant) within the context of the so-called
running vacuum models (RVM's) of the cosmic evolution. Recently, compelling
evidence has been provided showing that these models are able to fit the main
cosmological data (SNIa+BAO+H(z)+LSS+BBN+CMB) significantly better than the
concordance $\Lambda$CDM model. Specifically, the vacuum parameters of the RVM
(i.e. those responsible for the dynamics of the vacuum energy) prove to be
nonzero at a confidence level $\gtrsim3\sigma$. Here we use such remarkable
status of the RVM's to make definite predictions on the cosmic time variation
of the fundamental constants. It turns out that the predicted variations are
close to the present observational limits. Furthermore, we find that the time
variation of the dark matter particles should be crucially involved in the
total mass variation of our Universe. A positive measurement of this kind of
effects could be interpreted as strong support to the "micro and macro
connection" (viz. the dynamical feedback between the evolution of the
cosmological parameters and the time variation of the fundamental constants of
the microscopic world), previously proposed by two of us (HF and JS).


title:
The Grauert--Grothendieck complex on differentiable spaces and a sheaf
  complex of Brylinski

abstract:
  We use the Grauert--Grothendieck complex on differentiable spaces to study
basic relative forms on the inertia space of a compact Lie group action on a
manifold. We prove that the sheaf complex of basic relative forms on the
inertia space is a fine resolution of Bryliski's sheaf of functions on the
inertia space.


title:
Development of a 3D tongue motion visualization platform based on
  ultrasound image sequences

abstract:
  This article describes the development of a platform designed to visualize
the 3D motion of the tongue using ultrasound image sequences. An overview of
the system design is given and promising results are presented. Compared to the
analysis of motion in 2D image sequences, such a system can provide additional
visual information and a quantitative description of the tongue 3D motion. The
platform can be useful in a variety of fields, such as speech production,
articulation training, etc.


title:
Deterministic aperiodic composite lattice-structured silicon thin films
  for photon management

abstract:
  Exotic manipulation of the flow of photons in nanoengineered semiconductor
materials with an aperiodic distribution of nanostructures plays a key role in
efficiency-enhanced and industrially viable broadband photonic technologies.
Through a generic deterministic nanotechnological route, in addition to
periodic, transversely quasicrystallographic or disordered random photonic
lattices, here we show scalable nanostructured semiconductor thin films on
large area nanoimprinted substrates up to 4cm^2 with advanced functional
features of aperiodic composite nanophotonic lattices having tailorable
supercell tiles. The richer Fourier spectra of the presented artificially
nanostructured materials with well-defined lattice point morphologies are
designed functionally akin to two-dimensional incommensurate intergrowth
aperiodic lattices-comprising periodic photonic crystals and in-plane
quasicrystals as subgroups. The composite photonic lattice-structured
crystalline silicon thin films with tapered nanoholes or nanocone-nanoholes are
presented showing up to +30 % achievable short circuit current density in
comparison to a periodic counterpart where as it is up to +190 % in comparison
to a reference unstructured silicon thin film of 300 nanometers of thickness.
In view of scalable bottom-up integrated device fabrication processes, the
structural analysis is further extended to liquid phase crystallized
double-side-textured deterministic aperiodic lattice-structured 10 micrometers
thick large area crystalline silicon film.


title:
Collective migration under hydrodynamic interactions -- a computational
  approach

abstract:
  Substrate-based cell motility is essential for fundamental biological
processes, such as tissue growth, wound healing and immune response. Even if a
comprehensive understanding of this motility mode remains elusive, progress has
been achieved in its modeling using a whole cell physical model. The model
takes into account the main mechanisms of cell motility - actin polymerization,
substrate mediated adhesion and actin-myosin dynamics and combines it with
steric cell-cell and hydrodynamic interactions. The model predicts the onset of
collective cell migration, which emerges spontaneously as a result of inelastic
collisions of neighboring cells. Each cell here modeled as an active polar gel,
is accomplished with two vortices if it moves. Open collision of two cells the
two vortices which come close to each other annihilate. This leads to a
rotation of the cells and together with the deformation and the reorientation
of the actin filaments in each cell induces alignment of these cells and leads
to persistent translational collective migration. The effect for low Reynolds
numbers is as strong as in the non-hydrodynamic model, but it decreases with
increasing Reynolds number.


title:
First detections of the key prebiotic molecule PO in star-forming
  regions

abstract:
  Phosphorus is a crucial element in biochemistry, especially the P-O bond,
which is key for the formation of the backbone of the deoxyribonucleic acid. So
far, PO has only been detected towards the envelope of evolved stars, and never
towards star-forming regions. We report the first detections of PO towards two
massive star-forming regions, W51 e1/e2 and W3(OH), using data from the IRAM
30m telescope. PN has also been detected towards the two regions. The abundance
ratio PO/PN is 1.8 and 3 for W51 and W3(OH), respectively. Our chemical model
indicates that the two molecules are chemically related and are formed via
gas-phase ion-molecule and neutral-neutral reactions during the cold collapse.
The molecules freeze out onto grains at the end of the collapse and desorb
during the warm-up phase once the temperature reaches 35 K. Similar abundances
of the two species are expected during a period of 5x10^{4} yr at the early
stages of the warm-up phase, when the temperature is in the range 35-90 K. The
observed molecular abundances of 10^{-10} are predicted by the model if a
relatively high initial abundance of 5x10^{-9} of depleted phosphorus is
assumed.


title:
Modeling the band structure of the higher manganese silicides starting
  from Mn$_4$Si$_7$

abstract:
  The higher manganese silicides (HMS), with the chemical formula MnSi$_x$($x
\approx 1.73 - 1.75$), have been attracted a lot of attention due to their
potential application as thermoelectric materials. While the electronic band
structures of HMS have been previously studied using first principle
calculations, the relation between crystal structures of Mn and Si atoms and
their band structures is not well understood. Here we study Mn$_4$Si$_7$ using
first principle calculations and show that a half cell consisting of five Mn
atoms is the essential building block for Mn$_4$Si$_7$. Using this insight, we
construct a minimal tight-binding model for Mn$_4$Si$_7$ and other HMS
including Mn$_{11}$Si$_{19}$ and Mn$_{15}$Si$_{26}$. The role played by the Si
atoms and possible ways to achieve higher figure of merit are also discussed.


title: Softness and Amplitudes' Positivity for Spinning Particles

abstract:
  We derive positivity bounds for scattering amplitudes of particles with
arbitrary spin using unitarity, analyticity and crossing symmetry. The bounds
imply the positivity of certain low-energy coefficients of the effective action
that controls the dynamics of the light degrees of freedom. We show that
low-energy amplitudes strictly softer than $O(p^4)$ do not admit unitary
ultraviolet completions unless the theory is free. This enforces a bound on the
energy growth of scattering amplitudes in the region of validity of the
effective theory. We discuss explicit examples including the Goldstino from
spontaneous supersymmetry breaking, and the theory of a spin-1/2 fermion with a
shift symmetry.


title:
Solar coronal magnetic fields derived using seismology techniques
  applied to omnipresent sunspot waves

abstract:
  Sunspots on the surface of the Sun are the observational signatures of
intense manifestations of tightly packed magnetic field lines, with
near-vertical field strengths exceeding 6,000 G in extreme cases. It is well
accepted that both the plasma density and the magnitude of the magnetic field
strength decrease rapidly away from the solar surface, making high-cadence
coronal measurements through traditional Zeeman and Hanle effects difficult
since the observational signatures are fraught with low-amplitude signals that
can become swamped with instrumental noise. Magneto-hydrodynamic (MHD)
techniques have previously been applied to coronal structures, with single and
spatially isolated magnetic field strengths estimated as 9-55 G. A drawback
with previous MHD approaches is that they rely on particular wave modes
alongside the detectability of harmonic overtones. Here we show, for the first
time, how omnipresent magneto-acoustic waves, originating from within the
underlying sunspot and propagating radially outwards, allow the spatial
variation of the local coronal magnetic field to be mapped with high precision.
We find coronal magnetic field strengths of 32 +/- 5 G above the sunspot, which
decrease rapidly to values of approximately 1 G over a lateral distance of 7000
km, consistent with previous isolated and unresolved estimations. Our results
demonstrate a new, powerful technique that harnesses the omnipresent nature of
sunspot oscillations to provide magnetic field mapping capabilities close to a
magnetic source in the solar corona.


title:
Accretion disk signatures in Type I X-ray Bursts: prospects for future
  missions

abstract:
  Type I X-ray bursts and superbursts from accreting neutron stars illuminate
the accretion disk and produce a reflection signal that evolves as the burst
fades. Examining the evolution of reflection features in the spectra will give
insight into the burst-disk interaction, a potentially powerful probe of
accretion disk physics. At present, reflection has been observed during only
two bursts of exceptional duration. We investigate the detectability of
reflection signatures with four of the latest well-studied X-ray observatory
concepts: Hitomi, NICER, Athena, and LOFT. Burst spectra are modeled for
different values for the flux, temperature, and the disk ionization parameter,
which are representative for most known bursts and sources. The effective area
and through-put of a Hitomi-like telescope are insufficient for characterizing
burst reflection features. NICER and Athena will detect reflection signatures
in Type I bursts with peak fluxes $\ge 10^{-7.5}$ erg cm$^{-2}$ s$^{-1}$, and
also effectively constrain the reflection parameters for bright bursts with
fluxes of $10^{-7}$ erg cm$^{-2}$ s$^{-1}$ in exposures of several seconds.
Thus, these observatories will provide crucial new insight into the interaction
of accretion flows and X-ray bursts. For sources with low line-of-sight
absorption, the wide band-pass of these instruments allows for the detection of
soft X-ray reflection features, which are sensitive to the disk metallicity and
density. The large collecting area that is part of the LOFT design would
revolutionize the field by tracing the evolution of the accretion geometry in
detail throughout short bursts.


title:
Exploiting jet binning to identify the initial state of high-mass
  resonances

abstract:
  If a new high-mass resonance is discovered at the Large Hadron Collider,
model-independent techniques to identify the production mechanism will be
crucial to understand its nature and effective couplings to Standard Model
particles. We present a powerful and model-independent method to infer the
initial state in the production of any high-mass color-singlet system by using
a tight veto on accompanying hadronic jets to divide the data into two mutually
exclusive event samples (jet bins). For a resonance of several hundred GeV, the
jet binning cut needed to discriminate quark and gluon initial states is in the
experimentally accessible range of several tens of GeV. It also yields
comparable cross sections for both bins, making this method viable already with
the small event samples available shortly after a discovery. Theoretically, the
method is made feasible by utilizing an effective field theory setup to compute
the jet cut dependence precisely and model independently and to systematically
control all sources of theoretical uncertainties in the jet binning, as well as
their correlations. We use a 750 GeV scalar resonance as an example to
demonstrate the viability of our method.


title: Cosmological Simulations of Dwarf Galaxies with Cosmic Ray Feedback

abstract:
  We perform zoom-in cosmological simulations of a suite of dwarf galaxies,
examining the impact of cosmic-rays generated by supernovae, including the
effect of diffusion. We first look at the effect of varying the uncertain
cosmic ray parameters by repeatedly simulating a single galaxy. Then we fix the
comic ray model and simulate five dwarf systems with virial masses range from
8-30 $\times 10^{10}$ Msun. We find that including cosmic ray feedback (with
diffusion) consistently leads to disk dominated systems with relatively flat
rotation curves and constant star formation rates. In contrast, our purely
thermal feedback case results in a hot stellar system and bursty star
formation. The CR simulations very well match the observed baryonic
Tully-Fisher relation, but have a lower gas fraction than in real systems. We
also find that the dark matter cores of the CR feedback galaxies are cuspy,
while the purely thermal feedback case results in a substantial core.


title:
The multi-faceted Type II-L supernova 2014G from pre-maximum to nebular
  phase

abstract:
  We present multi-band ultraviolet, optical, and near-infrared photometry,
along with visual-wavelength spectroscopy, of supernova (SN) 2014G in the
nearby galaxy NGC 3448 (25 Mpc). The early-phase spectra show strong emission
lines of the high ionisation species He II/N IV/C IV during the first 2-3 d
after explosion, traces of a metal-rich CSM probably due to pre-explosion mass
loss events. These disappear by day 9 and the spectral evolution then continues
matching that of normal Type II SNe. The post-maximum light curve declines at a
rate typical of Type II-L class. The extensive photometric coverage tracks the
drop from the photospheric stage and constrains the radioactive tail, with a
steeper decline rate than that expected from the $^{56}$Co decay if
$\gamma$-rays are fully trapped by the ejecta. We report the appearance of an
unusual feature on the blue-side of H$\alpha$ after 100 d, which evolves to
appear as a flat spectral feature linking H$\alpha$ and the O I doublet. This
may be due to interaction of the ejecta with a strongly asymmetric, and
possibly bipolar CSM. Finally, we report two deep spectra at ~190 and 340 d
after explosion, the latter being arguably one of the latest spectra for a Type
II-L SN. By modelling the spectral region around the Ca II, we find a
supersolar Ni/Fe production. The strength of the O I $\lambda\lambda$6300,6363
doublet, compared with synthetic nebular spectra, suggests a progenitor with a
zero-age main-sequence mass between 15 and 19 M$_\odot$.


title: 450 Days of Type II SN 2013ej in Optical and Near-Infrared

abstract:
  We present optical and near-infrared photometric and spectroscopic
observations of SN 2013ej, in galaxy M74, from 1 to 450 days after the
explosion. SN 2013ej is a hydrogen-rich supernova, classified as a Type IIL due
to its relatively fast decline following the initial peak. It has a relatively
high peak luminosity (absolute magnitude M$_\rm{V}$ = -17.6) but a small
$^{56}$Ni production of ~0.023 M$_\odot$. Its photospheric evolution is similar
to other Type II SNe, with shallow absorption in the H{\alpha} profile typical
for a Type IIL. During transition to the radioactive decay tail at ~100 days,
we find the SN to grow bluer in B - V colour, in contrast to some other Type II
supernovae. At late times, the bolometric light curve declined faster than
expected from $^{56}$Co decay and we observed unusually broad and asymmetric
nebular emission lines. Based on comparison of nebular emission lines most
sensitive to the progenitor core mass, we find our observations are best
matched to synthesized spectral models with a M$_\rm{ZAMS}$ = 12 - 15 M$_\odot$
progenitor. The derived mass range is similar to but not higher than the mass
estimated for Type IIP progenitors. This is against the idea that Type IIL are
from more massive stars. Observations are consistent with the SN having a
progenitor with a relatively low-mass envelope.


title: A Primer on Unifying Debris Disk Morphologies

abstract:
  A "minimum model" for debris disks consists of a narrow ring of parent
bodies, secularly forced by a single planet on a possibly eccentric orbit,
colliding to produce dust grains that are perturbed by stellar radiation
pressure. We demonstrate how this minimum model can reproduce a wide variety of
disk morphologies imaged in scattered starlight. Five broad categories of disk
shape can be captured: "rings," "needles," "ships-and-wakes," "bars," and
"moths (a.k.a. fans)," depending on the viewing geometry. Moths can also sport
"double wings." We explain the origin of morphological features from first
principles, exploring the dependence on planet eccentricity, disk inclination
dispersion, and the parent body orbital phases at which dust grains are born. A
key determinant in disk appearance is the degree to which dust grain orbits are
apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk
should serve as a reference for more detailed models tailored to individual
systems. We use the intuition gained from our guidebook of disk morphologies to
interpret, informally, the images of a number of real-world debris disks. These
interpretations suggest that the farthest reaches of planetary systems are
perturbed by eccentric planets, possibly just a few Earth masses each.


title: High Energy Neutrinos from Recent Blazar Flares

abstract:
  The energy density of cosmic neutrinos measured by IceCube matches the one
observed by Fermi in extragalactic photons that predominantly originate in
blazars. This has inspired attempts to match Fermi sources with IceCube
neutrinos. A spatial association combined with a coincidence in time with a
flaring source may represent a smoking gun for the origin of the IceCube flux.
In June 2015, the Fermi Large Area Telescope observed an intense flare from
blazar 3C 279 that exceeded the steady flux of the source by a factor of forty
for the duration of a day. We show that IceCube is likely to observe neutrinos,
if indeed hadronic in origin, in data that are still blinded at this time. We
also discuss other opportunities for coincident observations that include a
recent flare from blazar 1ES 1959+650 that previously produced an intriguing
coincidence with AMANDA observations.


title: Supersymmetric partition functions on Riemann surfaces

abstract:
  We present a compact formula for the supersymmetric partition function of 2d
N=(2,2), 3d N=2 and 4d N=1 gauge theories on $\Sigma_g \times T^n$ with partial
topological twist on $\Sigma_g$, where $\Sigma_g$ is a Riemann surface of
arbitrary genus and $T^n$ is a torus with n=0,1,2, respectively. In 2d we also
include certain local operator insertions, and in 3d we include Wilson line
operator insertions along $S^1$. For genus g=1, the formula computes the Witten
index. We present a few simple Abelian and non-Abelian examples, including new
tests of non-perturbative dualities. We also show that the large N partition
function of ABJM theory on $\Sigma_g \times S^1$ reproduces the
Bekenstein-Hawking entropy of BPS black holes in AdS$_4$ whose horizon has
$\Sigma_g$ topology.


title: Cosmological backreaction in higher-derivative gravity expansions

abstract:
  We calculate a general effective stress-energy tensor induced by cosmological
inhomogeneity in effective theories of gravity where the action is
Taylor-expandable in the Riemann tensor and covariant derivatives of the
Riemann tensor. This is of interest as an effective fluid that might provide an
alternative to the cosmological constant, but it also applies to gravitational
waves. We use an adaptation of Green and Wald's weak-averaging framework, which
averages over perturbations in the field equation where the perturbation length
scales are small compared to the averaging scale. In this adaptation, the
length scale of the effective theory, $1/M$, is also taken to be small compared
with the averaging scale. This ensures that the perturbation length scales
remain in fixed proportion to the length scale of the effective theory as the
cosmological averaging scale is taken to be large. We find that backreaction
from higher-derivative terms in the effective action can continue to be
important in the late universe, given a source of sufficiently high-frequency
metric perturbations. This backreaction might also provide a window on exotic
particle physics in the far ultraviolet.


title: MCMC with Strings and Branes: The Suburban Algorithm

abstract:
  Motivated by the physics of strings and branes, we introduce a general suite
of Markov chain Monte Carlo (MCMC) "suburban samplers" (i.e., spread out
Metropolis). The suburban algorithm involves an ensemble of statistical agents
connected together by a random network. Performance of the collective in
reaching a fast and accurate inference depends primarily on the average number
of nearest neighbor connections. Increasing the average number of neighbors
above zero initially leads to an increase in performance, though there is a
critical connectivity with effective dimension d_eff ~ 1, above which
"groupthink" takes over, and the performance of the sampler declines.

categories: stat.CO cond-mat.dis-nn hep-th physics.comp-ph


title: Singlet-Catalyzed Electroweak Phase Transitions in the 100 TeV Frontier

abstract:
  We study the prospects for probing a gauge singlet scalar-driven strong first
order electroweak phase transition with a future proton-proton collider in the
100 TeV range. Singlet-Higgs mixing enables resonantly-enhanced di-Higgs
production, potentially aiding discovery prospects. We perform Monte Carlo
scans of the parameter space to identify regions associated with a strong
first-order electroweak phase transition, analyze the corresponding di-Higgs
signal, and select a set of benchmark points that span the range of di-Higgs
signal strengths. For the $b\bar{b}\gamma\gamma$ and $4\tau$ final states, we
investigate discovery prospects for each benchmark point for the high
luminosity phase of the Large Hadron Collider and for a future $pp$ collider
with $\sqrt{s}$ = 50, 100, or 200 TeV. We find that any of these future
collider scenarios could significantly extend the reach beyond that of the high
luminosity LHC, and that with $\sqrt{s}$ = 100 TeV (200 TeV) and 30 ab$^{-1}$,
the full region of parameter space favorable to strong first order electroweak
phase transitions is almost fully (fully) discoverable.


title: Empowering line intensity mapping to study early galaxies

abstract:
  Line intensity mapping is a superb tool to study the collective radiation
from early galaxies. However, the method is hampered by the presence of strong
foregrounds, mostly produced by low-redshift interloping lines. We present here
a general method to overcome this problem which is robust against foreground
residual noise and based on the cross-correlation function $\psi_{\alpha L}(r)$
between diffuse line emission and Ly$\alpha$ emitters (LAE). We compute the
diffuse line (Ly$\alpha$ is used as an example) emission from galaxies in a
$(800{\rm Mpc})^3$ box at $z = 5.7$ and $6.6$. We divide the box in slices and
populate them with $14000(5500)$ LAEs at $z = 5.7(6.6)$, considering duty
cycles from $10^{-3}$ to $1$. Both the LAE number density and slice volume are
consistent with the expected outcome of the Subaru HSC survey. We add gaussian
random noise with variance $\sigma_{\rm N}$ up to 100 times the variance of the
Ly$\alpha$ emission, $\sigma_\alpha$, to simulate foregrounds and compute
$\psi_{\alpha L}(r)$. We find that the signal-to-noise of the observed
$\psi_{\alpha L}(r)$ does not change significantly if $\sigma_{\rm N} \le 10
\sigma_\alpha$ and show that in these conditions the mean line intensity,
$I_{Ly\alpha}$, can be precisely recovered independently of the LAE duty cycle.
Even if $\sigma_{\rm N} = 100 \sigma_\alpha$, $I_\alpha$ can be constrained
within a factor $2$. The method works equally well for any other line (e.g. HI
21 cm, [CII], HeII) used for the intensity mapping experiment.


title: Ising Anyons in Frustration-Free Majorana-Dimer Models

abstract:
  Dimer models have long been a fruitful playground for understanding
topological physics. Here we introduce a new class - termed Majorana-dimer
models - wherein bosonic dimers are decorated with pairs of Majorana modes. We
find that the simplest examples of such systems realize an intriguing,
intrinsically fermionic phase of matter that can be viewed as the product of a
chiral Ising theory, which hosts deconfined non-Abelian quasiparticles, and a
topological $p_x - ip_y$ superconductor. While the bulk anyons are described by
a single copy of the Ising theory, the edge remains fully gapped. Consequently,
this phase can arise in exactly solvable, frustration-free models. We describe
two parent Hamiltonians: one generalizes the well-known dimer model on the
triangular lattice, while the other is most naturally understood as a model of
decorated fluctuating loops on a honeycomb lattice. Using modular
transformations, we show that the ground-state manifold of the latter model
unambiguously exhibits all properties of the $\text{Ising} \times (p_x-ip_y)$
theory. We also discuss generalizations with more than one Majorana mode per
site, which realize phases related to Kitaev's 16-fold way in a similar
fashion.


title: Computation of the Similarity Class of the p-Curvature

abstract:
  The $p$-curvature of a system of linear differential equations in positive
characteristic $p$ is a matrix that measures how far the system is from having
a basis of polynomial solutions. We show that the similarity class of the
$p$-curvature can be determined without computing the $p$-curvature itself.
More precisely, we design an algorithm that computes the invariant factors of
the $p$-curvature in time quasi-linear in $\sqrt p$. This is much less than the
size of the $p$-curvature, which is generally linear in $p$. The new algorithm
allows to answer a question originating from the study of the Ising model in
statistical physics.


title:
Conjugacy of Cartan Subalgebras in Solvable Leibniz Algebras and Real
  Leibniz Algebras

abstract:
  We extend conjugacy results from Lie algebras to their Leibniz algebra
generalizations. The proofs in the Lie case depend on anti-commutativity. Thus
it is necessary to find other paths in the Leibniz case. Some of these results
involve Cartan subalgebras. Our results can be used to extend other results on
Cartan subalgebras. We show an example here and others will be shown in future
work.


title:
Perturbative Construction of Stationary Randall-Sundrum II Black Holes
  on a 5-Brane

abstract:
  We numerically construct large Randall-Sundrum II brane black holes in 4 and
5 dimensions from associated AdS/CFT spacetimes. Our solutions are leading
order perturbations of a representative of the boundary conformal structure of
the AdS spacetime sourced by the dual CFT stress tensor. The 4-dimensional
solutions are static perturbations of the Euclidean Schwarzschild metric, while
the 5-dimensional solutions are perturbations of the Myers-Perry metric with
equal angular momenta. We compare the former with previous numerical results
for Randall-Sundrum bulk black holes and find good agreement down to a horizon
radius of about rH ~30l. The latter are the first numerical results pertaining
to rotating Randall-Sundrum black holes. They have the same entropy, but a
larger horizon area than Myers-Perry black holes of the same mass and angular
momentum.


title:
Conductivity of weakly disordered metals close to a "ferromagnetic"
  quantum critical point

abstract:
  We calculate analytically the conductivity of weakly disordered metals close
to a "ferromagnetic" quantum critical point in the low temperature regime.
Ferromagnetic in the sense that the effective carrier potential $V(q,\omega)$,
due to critical fluctuations, is peaked at zero momentum $q=0$. Vertex
corrections, due to both critical fluctuations and impurity scattering, are
explicitly considered. We find that only the vertex corrections due to impurity
scattering, combined with the self-energy, generate appreciable effects as a
function of the temperature $T$ and the control parameter $a$, which measures
the proximity to the critical point. Our results are consistent with
resistivity experiments in several materials displaying typical Fermi liquid
behavior, but with a diverging prefactor of the $T^2$ term for small $a$.


title:
Short-time height distribution in 1d KPZ equation: starting from a
  parabola

abstract:
  We study the probability distribution $\mathcal{P}(H,t,L)$ of the surface
height $h(x=0,t)=H$ in the Kardar-Parisi-Zhang (KPZ) equation in $1+1$
dimension when starting from a parabolic interface, $h(x,t=0)=x^2/L$. The
limits of $L\to\infty$ and $L\to 0$ have been recently solved exactly for any
$t>0$. Here we address the early-time behavior of $\mathcal{P}(H,t,L)$ for
general $L$. We employ the weak-noise theory - a variant of WKB approximation
-- which yields the optimal history of the interface, conditioned on reaching
the given height $H$ at the origin at time $t$. We find that at small $H$
$\mathcal{P}(H,t,L)$ is Gaussian, but its tails are non-Gaussian and highly
asymmetric. In the leading order and in a proper moving frame, the tails behave
as $-\ln \mathcal{P}= f_{+}|H|^{5/2}/t^{1/2}$ and $f_{-}|H|^{3/2}/t^{1/2}$. The
factor $f_{+}(L,t)$ monotonically increases as a function of $L$, interpolating
between time-independent values at $L=0$ and $L=\infty$ that were previously
known. The factor $f_{-}$ is independent of $L$ and $t$, signalling
universality of this tail for a whole class of deterministic initial
conditions.


title: CFT Duals for Accelerating Black Holes

abstract:
  The near horizon geometry of the rotating C-metric, describing accelerating
Kerr-Newman black holes, is analysed. It is shown that, at extremality, even
though not it is isomorphic to the extremal Kerr-Newman, it remains a warped
and twisted product of $AdS_2 \times S^2$. Therefore the methods of the
Kerr/CFT correspondence can successfully be applied to build a CFT dual model,
whose entropy reproduce, through the Cardy formula, the Beckenstein-Hawking
entropy of the accelerating black hole. The mass of accelerating Kerr-Newman
black hole, which fulfil the first law of thermodynamics, is presented. Further
generalisation in presence of an external Melvin-like magnetic field, used to
regularise the conical singularity characteristic of the C-metrics, shows that
the Kerr/CFT correspondence can be applied also for the accelerating and
magnetised extremal black holes.


title:
Generalized Darboux transformation and higher-order rogue wave solutions
  to the Manakov system

abstract:
  In this paper, we construct a generalized recursive Darboux transformation of
a focusing vector nonlinear Schr\"odinger equation known as the Manakov system.
We apply this generalized recursive Darboux transformation to the Lax-pairs of
this system in view of generating the Nth-order vector generalization rogue
wave solutions with the same spectral parameter through a direct iteration
rule. As a result, we discuss the first, second and third-order vector
generalization rogue wave solutions while illustrating these features with some
depictions. We show that higher-order rogue wave solutions depend on the values
of their free parameters.


title:
XMMSL1J063045.9-603110: a tidal disruption event fallen into the back
  burner

abstract:
  Black holes at the centre of quiescent galaxies can be switched on when they
accrete gas that is gained from stellar tidal disruptions. A star approaching a
black hole on a low angular momentum orbit may be ripped apart by tidal forces,
which triggers raining down of a fraction of stellar debris onto the compact
object through an accretion disc and powers a bright flare. In this paper we
discuss XMMSL1J063045.9-603110 as a candidate object for a tidal disruption
event. The source has recently been detected to be bright in the soft X-rays
during an XMM-Newton slew and later showed an X-ray flux decay by a factor of
about 10 in twenty days. We analyse XMM-Newton and Swift data.
XMMSL1J063045.9-603110 shows several features typical of tidal disruption
events: the X-ray spectrum shows the characteristics of a spectrum arising from
a thermal accretion disc, the flux decay follows a t^-5/3 law, and the flux
variation is > 350. Optical observations testify that XMMSL1J063045.9-603110 is
probably associated with an extremely small galaxy or even a globular cluster,
which suggests that intermediate-mass black holes are located in the cores of
(at least) some of them.


title: Hardware-Based ADMM-LP Decoding

abstract:
  In this paper we present an FPGA-based implementation of linear programming
(LP) decoding. LP decoding frames error correction as an optimization problem.
This is in contrast to variants of belief propagation (BP) decoding that view
error correction as a problem of graphical inference. There are many advantages
to taking the optimization perspective: convergence guarantees, improved
performance in certain regimes, and a methodology for incorporating the latest
developments in optimization techniques. However, LP decoding, when implemented
with standard LP solvers, does not easily scale to the blocklengths of modern
error-correction codes. In earlier work, we showed that by drawing on
decomposition methods from optimization theory, specifically the alternating
direction method of multipliers (ADMM), we could build an LP decoding solver
that was competitive with BP, both in terms of performance and speed. We also
observed empirically that LP decoders have much better high-SNR performance in
the "error floor" regime, a trait of particular relevance to optical transport
and storage applications. While our previous implementation was in floating
point, in this paper we report initial results of a fixed-point, hardware-based
realization of our ADMM-LP decoder.


title: Applications of fidelity measures to complex quantum systems

abstract:
  We revisit the fidelity as a measure for the stability and the complexity of
the quantum motion of single and many-body systems. Within the context of cold
atoms, we present on overview of applications of two fidelities which we call
static and dynamical fidelity, respectively. The static fidelity applies to
quantum problems which can be diagonalized since it is defined via the
eigenfunctions. In particular, we show that the static fidelity is a highly
effective practical detector of avoided crossings characterizing the complexity
of the systems and their evolutions. The dynamical fidelity is defined via the
time-dependent wave functions. Focussing on the quantum kicked rotor system, we
highlight a few practical applications of fidelity measurements in order to
better understand the large variety of dynamical regimes of this paradigm of a
low-dimensional system with mixed regular-chaotic phase space.


title:
The JCMT Gould Belt Survey: Evidence for Dust Grain Evolution in Perseus
  Star-forming Clumps

abstract:
  The dust emissivity spectral index, $\beta$, is a critical parameter for
deriving the mass and temperature of star-forming structures, and consequently
their gravitational stability. The $\beta$ value is dependent on various dust
grain properties, such as size, porosity, and surface composition, and is
expected to vary as dust grains evolve. Here we present $\beta$, dust
temperature, and optical depth maps of the star-forming clumps in the Perseus
Molecular Cloud determined from fitting SEDs to combined Herschel and JCMT
observations in the 160 $\mu$m, 250 $\mu$m, 350 $\mu$m, 500 $\mu$m, and 850
$\mu$m bands. Most of the derived $\beta$, and dust temperature values fall
within the ranges of 1.0 - 2.7 and 8 - 20 K, respectively. In Perseus, we find
the $\beta$ distribution differs significantly from clump to clump, indicative
of grain growth. Furthermore, we also see significant, localized $\beta$
variations within individual clumps and find low $\beta$ regions correlate with
local temperature peaks, hinting at the possible origins of low $\beta$ grains.
Throughout Perseus, we also see indications of heating from B stars and
embedded protostars, as well evidence of outflows shaping the local landscape.


title:
Perfect Matchings in Inhomogeneous Random Bipartite Graphs in Random
  Environment

abstract:
  In this note we study inhomogeneous random bipartite graphs in random
environment. These graphs can be thought of as an extension of the classical
Erd\"os-R\'enyi random graphs in a random environment. We show that the
expected number of perfect matchings obeys a precise quenched asymptotic and
that it can be approximated using an iterative process that converges
exponentially fast.


title:
Numerical Solution of the Steady-State Navier-Stokes Equations using
  Empirical Interpolation Methods

abstract:
  Reduced-order modeling is an efficient approach for solving parameterized
discrete partial differential equations when the solution is needed at many
parameter values. An offline step approximates the solution space and an online
step utilizes this approximation, the reduced basis, to solve a smaller reduced
problem at significantly lower cost, producing an accurate estimate of the
solution. For nonlinear problems, however, standard methods do not achieve the
desired cost savings. Empirical interpolation methods represent a modification
of this methodology used for cases of nonlinear operators or nonaffine
parameter dependence. These methods identify points in the discretization
necessary for representing the nonlinear component of the reduced model
accurately, and they incur online computational costs that are independent of
the spatial dimension $N$. We will show that empirical interpolation methods
can be used to significantly reduce the costs of solving parameterized versions
of the Navier-Stokes equations, and that iterative solution methods can be used
in place of direct methods to further reduce the costs of solving the algebraic
systems arising from reduced-order models.


title: Displaying tangles and non-sequential separations

abstract:
  We show that, for any graph or matroid, there is a tree that simultaneously
distinguishes its maximal tangles, and, for each maximal tangle $\mathcal{T}$
that satisfies an additional robustness condition, displays all of the
non-trivial separations relative to $\mathcal{T}$, up to a natural equivalence.


title:
Holographik, the k-essential approach to interactive models with
  modified holographic Ricci dark energy

abstract:
  We make a scalar representation of interactive models with cold dark matter
and modified holographic Ricci dark energy through unified models driven by
scalar fields with non-canonical kinetic term. These models are applications of
the formalism of exotic k-essences generated by the global description of
cosmological models with two interactive fluids in the dark sector and in these
cases they correspond to usual k-essences. The formalism is applied to the
cases of constant potential in Friedmann-Robertson-Walker geometries.


title:
Many new variable stars discovered in the core of the globular cluster
  NGC 6715 (M54) with EMCCD observations

abstract:
  We show the benefits of using Electron-Multiplying CCDs and the shift-and-add
technique as a tool to minimise the effects of the atmospheric turbulence such
as blending between stars in crowded fields and to avoid saturated stars in the
fields observed. We intend to complete, or improve, the census of the variable
star population in globular cluster NGC~6715.
  Our aim is to obtain high-precision time-series photometry of the very
crowded central region of this stellar system via the collection of better
angular resolution images than has been previously achieved with conventional
CCDs on ground-based telescopes.
  Observations were carried out using the Danish 1.54-m Telescope at the ESO La
Silla observatory in Chile. The telescope is equipped with an
Electron-Multiplying CCD that allowed to obtain short-exposure-time images (ten
images per second) that were stacked using the shift-and-add technique to
produce the normal-exposure-time images (minutes). The high precision
photometry was performed via difference image analysis employing the DanDIA
pipeline. We attempted automatic detection of variable stars in the field.
  We statistically analysed the light curves of 1405 stars in the crowded
central region of NGC~6715 to automatically identify the variable stars present
in this cluster. We found light curves for 17 previously known variable stars
near the edges of our reference image (16 RR Lyrae and 1 semi-regular) and we
discovered 67 new variables (30 RR Lyrae, 21 long-period irregular, 3
semi-regular, 1 W Virginis, 1 eclipsing binary, and 11 unclassified).
Photometric measurements for these stars are available in electronic form
through the Strasbourg Astronomical Data Centre.


title: Vincia for Hadron Colliders

abstract:
  We present the first public implementation of antenna-based QCD initial- and
final-state showers. The shower kernels are $2\to 3$ antenna functions, which
capture not only the collinear dynamics but also the leading soft (coherent)
singularities of QCD matrix elements. We define the evolution measure to be
inversely proportional to the leading poles, hence gluon emissions are evolved
in a $p_\perp$ measure inversely proportional to the eikonal, while processes
that only contain a single pole (e.g., $g\to q\bar{q}$) are evolved in
virtuality. Non-ordered emissions are allowed, suppressed by an additional
power of $1/Q^2$. Recoils and kinematics are governed by exact on-shell $2\to
3$ phase-space factorisations. This first implementation is limited to massless
QCD partons and colourless resonances. Tree-level matrix-element corrections
are included for QCD up to $\mathcal{O}(\alpha_s^4)$ (4 jets), and for
Drell-Yan and Higgs production up to $\mathcal{O}(\alpha_s^3)$ ($V/H$ + 3
jets). The resulting algorithm has been made publicly available in Vincia 2.0.


title:
Efficient and Private Approximations of Distributed Databases
  Calculations

abstract:
  In recent years, an increasing amount of data is collected in different and
often, not cooperative, databases. The problem of privacy-preserving,
distributed calculations over separated databases and, a relative to it, issue
of private data release were intensively investigated. However, despite a
considerable progress, computational complexity, due to an increasing size of
data, remains a limiting factor in real-world deployments, especially in case
of privacy-preserving computations.
  In this paper, we present a general method for trade off between performance
and accuracy of distributed calculations by performing data sampling. Sampling
was a topic of extensive research that recently received a boost of interest.
We provide a sampling method targeted at separate, non-collaborating,
vertically partitioned datasets. The method is exemplified and tested on
approximation of intersection set both without and with privacy-preserving
mechanism. An analysis of the bound on error as a function of the sample size
is discussed and heuristic algorithm is suggested to further improve the
performance. The algorithms were implemented and experimental results confirm
the validity of the approach.


title: Invariants of Lagrangian cobordisms via spectral numbers

abstract:
  We extend parts of the Lagrangian spectral invariants package recently
developed by Leclercq and Zapolsky to the theory of Lagrangian cobordism
developed by Biran and Cornea. This yields a nondegenerate Lagrangian "spectral
metric" which bounds the Lagrangian "cobordism metric" (recently introduced by
Cornea and Shelukhin) from below. It also yields a new numerical Lagrangian
cobordism invariant as well as new ways of computing certain asymptotic
Lagrangian spectral invariants explicitly.


title: HNN extensions and stackable groups

abstract:
  Stackability for finitely presented groups consists of a dynamical system
that iteratively moves paths into a maximal tree in the Cayley graph. Combining
with formal language theoretic restrictions yields auto- or algorithmic
stackability, which implies solvability of the word problem. In this paper we
give two new characterizations of the stackable property for groups, and use
these to show that every HNN extension of a stackable group is stackable. We
apply this to exhibit a wide range of Dehn functions that are admitted by
stackable and autostackable groups, as well as an example of a stackable group
with unsolvable word problem. We use similar methods to show that there exist
finitely presented metabelian groups that are non-constructible but admit an
autostackable structure.


title:
Investigations of metastable Ca2IrO4 epitaxial thin-films: systematic
  comparison with Sr2IrO4 and Ba2IrO4

abstract:
  We have synthesized thermodynamically metastable Ca2IrO4 thin-films on YAlO3
(110) substrates by pulsed laser deposition. The epitaxial Ca2IrO4 thin-films
are of K2NiF4-type tetragonal structure. Transport and optical spectroscopy
measurements indicate that the electronic structure of the Ca2IrO4 thin-films
is similar to that of Jeff = 1/2 spin-orbit-coupled Mott insulator Sr2IrO4 and
Ba2IrO4, with the exception of an increased gap energy. The gap increase is to
be expected in Ca2IrO4 due to its increased octahedral rotation and tilting,
which results in enhanced electron-correlation, U/W. Our results suggest that
the epitaxial stabilization growth of metastable-phase thin-films can be used
effectively for investigating layered iridates and various complex-oxide
systems.


title:
A globally convergent method for a 3-D inverse medium problem for the
  generalized Helmholtz equation

abstract:
  A 3-D inverse medium problem in the frequency domain is considered. Another
name for this problem is Coefficient Inverse Problem. The goal is to
reconstruct spatially distributed dielectric constants from scattering data.
Potential applications are in detection and identification of explosive-like
targets. A single incident plane wave and multiple frequencies are used. A new
numerical method is proposed. A theorem is proved, which claims that a small
neigborhood of the exact solution of that problem is reached by this method
without any advanced knowledge of that neighborhood. We call this property of
that numerical method "global convergence". Results of numerical experiments
for the case of the backscattering data are presented.


title: Remote Operations and Nightly Automation of The Red Buttes Observatory

abstract:
  We have implemented upgrades to the University of Wyoming's Red Buttes
Observatory (RBO) to allow remote and autonomous operations using the 0.6 m
telescope. Detailed descriptions of hardware and software components provide
sufficient information to guide upgrading similarly designed telescopes. We
also give a thorough description of the automated and remote operation modes
with intent to inform the construction of routines elsewhere. Because the
upgrades were largely driven by the intent to perform exoplanet transit
photometry, we discuss how this science informed the automation process. A
sample exoplanet transit observation serves to demonstrate RBO's capability to
perform precision photometry. The successful upgrades have equipped a legacy
observatory for a new generation of automated and rapid-response observations.


title:
How can the green sulfur bacteria use quantum computing for light
  harvesting?

abstract:
  Long lasting coherence in photosynthetic pigment-protein complexes has been
observed even at physiological temperatures. Experiments have demonstrated
quantum coherent behaviour in the long-time operation of the D-Wave quantum
computer as well. Quantum coherence is the common feature between the two
phenomena. An explanations for eight orders of magnitude discrepancy between
the single flux qubit coherence time and the long-time quantum behaviour of an
array of thousand flux qubits in the quantum computer was suggested within a
theory where the flux qubits are coupled to an environment of particles called
gravonons of high density of states The coherent evolution is in high
dimensional spacetime and can be understood as a solution of Schroedinger's
time-dependent equation.
  Explanations for the quantum beats observed in 2D Fourier transform
electronic spectroscopy of the Fenna-Matthews-Olson (FMO) protein complex in
the green sulfur bacteria are presently sought in constructing transport
theories based on quantum master equations where 'good' molecular vibrations
('coloured noise') in the chlorophyll and the surrounding protein scaffold
knock the exciton oscillations back into coherence. These 'good' vibrations are
claimed to have developed in three billion years of natural selection. These
theories, however, face the discomforting experimental observation that
"attempts to scramble vibrational modes or to shift resonances with isotopic
substitution miserably failed to affect the beating signals". As a possible way
out of this dilemma we adopted the formalism of the quantum computation to the
quantum beats in the FMO protein complex.


title:
Finding Needles in the Haystack: Harnessing Syslogs for Data Center
  Management

abstract:
  Network device syslogs are ubiquitous and abundant in modern data centers
with most large data centers producing millions of messages per day. Yet, the
operational information reflected in syslogs and their implications on
diagnosis or management tasks are poorly understood. Prevalent approaches to
understanding syslogs focus on simple correlation and abnormality detection and
are often limited to detection providing little insight towards diagnosis and
resolution.
  Towards improving data center operations, we propose and implement
Log-Prophet, a system that applies a toolbox of statistical techniques and
domain-specific models to mine detailed diagnoses. Log-Prophet infers causal
relationships between syslog lines and constructs succinct but valuable problem
graphs, summarizing root causes and their locality, including cascading
problems. We validate Log-Prophet using problem tickets and through operator
interviews. To demonstrate the strength of Log-Prophet, we perform an initial
longitudinal study of a large online service provider's data center. Our study
demonstrates that Log-Prophet significantly reduces the number of alerts while
highlighting interesting operational issues.


title: Scattering properties of PT-symmetric objects

abstract:
  We investigate the scattering response of parity-time (PT) symmetric
structures. We show that, due to the local flow of energy between gain and loss
regions, such systems can deflect light in unusual ways, as a function of the
gain/loss contrast. Such structures are highly anisotropic and their scattering
patterns can drastically change as a function of the angle of incidence. In
addition, we derive a modified optical theorem for PT-symmetric scattering
systems, and discuss its ramifications.


title: Carbon and Oxygen Abundances in Low Metallicity Dwarf Galaxies

abstract:
  The study of carbon and oxygen abundances yields information on the time
evolution and nucleosynthetic origins of these elements, yet remains relatively
unexplored. At low metallicities (12+log(O/H) < 8.0), nebular carbon
measurements are limited to rest-frame UV collisionally excited emission lines.
Therefore, we present UV spectrophotometry of 12 nearby, low-metallicity,
high-ionization HII regions in dwarf galaxies obtained with the Cosmic Origins
Spectrograph on the Hubble Space Telescope. We present the first analysis of
the C/O ratio in local galaxies based solely on simultaneous significant
detections of the UV O^+2 and C^+2 collisionally excited lines in seven of our
targets and five objects from the literature, to create a final sample of 12
significant detections. Our sample is complemented by optical SDSS spectra,
from which we measured the nebular physical conditions and oxygen abundances
using the direct method.
  At low metallicity (12+log(O/H) < 8.0), no clear trend is evident in C/O vs.
O/H for the present sample given the large dispersion observed. When combined
with recombination line observations at higher values of O/H, a general trend
of increasing C/O with increasing O/H is also viable, but with some significant
outliers. Additionally, we find the C/N ratio appears to be constant (but with
significant scatter) over a large range in oxygen abundance, indicating carbon
is predominantly produced by similar nucleosynthetic mechanisms as nitrogen. If
true, and our current understanding of nitrogen production is correct, this
would indicate that primary production of carbon (a flat trend) dominates at
low metallicity, but quasi-secondary production (an increasing trend) becomes
prominent at higher metallicities. A larger sample will be needed to determine
the true nature and dispersion of the relation.


title: Strong classification of purely infinite Cuntz-Krieger algebras

abstract:
  In 2006, Restorff completed the classification of all Cuntz-Krieger algebras
with finitely many ideals (i.e., those that are purely infinite) up to stable
isomorphism. He left open the questions concerning strong classification up to
stable isomorphism and unital classification. In this paper, we address both
questions. We show that any isomorphism between the reduced filtered K-theory
of two Cuntz-Krieger algebras with finitely many ideals lifts to a
*-isomorphism between the stabilized Cuntz-Krieger algebras. As a result, we
also obtain strong unital classification.


title: Web Infrastructure to Support e-Journal Preservation (and More)

abstract:
  E-journal preservation systems have to ingest millions of articles each year.
Ingest, especially of the "long tail" of journals from small publishers, is the
largest element of their cost. Cost is the major reason that archives contain
less than half the content they should. Automation is essential to minimize
these costs. This paper examines the potential for automation beyond the status
quo based on the API provided by CrossRef, ANSI/NISO Z39.99 ResourceSync, and
the provision of typed links in publishers' HTTP response headers. These
changes would not merely assist e-journal preservation and other cross-venue
scholarly applications, but would help remedy the gap that research has
revealed between DOIs' potential and actual benefits.


title: Inter-Battery Topic Representation Learning

abstract:
  In this paper, we present the Inter-Battery Topic Model (IBTM). Our approach
extends traditional topic models by learning a factorized latent variable
representation. The structured representation leads to a model that marries
benefits traditionally associated with a discriminative approach, such as
feature selection, with those of a generative model, such as principled
regularization and ability to handle missing data. The factorization is
provided by representing data in terms of aligned pairs of observations as
different views. This provides means for selecting a representation that
separately models topics that exist in both views from the topics that are
unique to a single view. This structured consolidation allows for efficient and
robust inference and provides a compact and efficient representation. Learning
is performed in a Bayesian fashion by maximizing a rigorous bound on the
log-likelihood. Firstly, we illustrate the benefits of the model on a synthetic
dataset,. The model is then evaluated in both uni- and multi-modality settings
on two different classification tasks with off-the-shelf convolutional neural
network (CNN) features which generate state-of-the-art results with extremely
compact representations.


title:
High Resolution Linear Polarimetric Imaging for the Event Horizon
  Telescope

abstract:
  Images of the linear polarization of synchrotron radiation around Active
Galactic Nuclei (AGN) identify their projected magnetic field lines and provide
key data for understanding the physics of accretion and outflow from
supermassive black holes. The highest resolution polarimetric images of AGN are
produced with Very Long Baseline Interferometry (VLBI). Because VLBI
incompletely samples the Fourier transform of the source image, any image
reconstruction that fills in unmeasured spatial frequencies will not be unique
and reconstruction algorithms are required. In this paper, we explore
extensions of the Maximum Entropy Method (MEM) to linear polarimetric VLBI
imaging. In contrast to previous work, our polarimetric MEM algorithm combines
a Stokes I imager that uses only bispectrum measurements that are immune to
atmospheric phase corruption with a joint Stokes Q and U imager that operates
on robust polarimetric ratios. We demonstrate the effectiveness of our
technique on 7- and 3-mm wavelength quasar observations from the VLBA and
simulated 1.3-mm Event Horizon Telescope observations of Sgr A* and M87.
Consistent with past studies, we find that polarimetric MEM can produce
superior resolution compared to the standard CLEAN algorithm when imaging
smooth and compact source distributions. As an imaging framework, MEM is highly
adaptable, allowing a range of constraints on polarization structure.
Polarimetric MEM is thus an attractive choice for image reconstruction with the
EHT.


title:
Matching asteroid population characteristics with a model constructed
  from the YORP-induced rotational fission hypothesis

abstract:
  From the results of a comprehensive asteroid population evolution model, we
conclude that the YORP-induced rotational fission hypothesis can be consistent
with the observed population statistics of small asteroids in the main belt
including binaries and contact binaries. The foundation of this model is the
asteroid rotation model of Marzari et al. (2011), which incorporates both the
YORP effect and collisional evolution. This work adds to that model the
rotational fission hypothesis and the binary evolution model of Jacobson &
Scheeres (2011). The asteroid population evolution model is highly constrained
by these and other previous works, and therefore it has only two significant
free parameters: the ratio of low to high mass ratio binaries formed after
rotational fission events and the mean strength of the binary YORP (BYORP)
effect. We successfully reproduce characteristic statistics of the small
asteroid population: the binary fraction, the fast binary fraction,
steady-state mass ratio fraction and the contact binary fraction. We find that
in order for the model to best match observations, rotational fission produces
high mass ratio ($> 0.2$) binary components with four to eight times the
frequency as low mass ratio ($< 0.2$) components, where the mass ratio is the
mass of the secondary component divided by the mass of the primary component.
This is consistent with post-rotational fission binary system mass ratio being
drawn from either a flat or a positive and shallow distribution, since the high
mass ratio bin is four times the size of the low mass ratio bin; this is in
contrast to the observed steady-state binary mass ratio, which has a negative
and steep distribution. This can be understood in the context of the
BYORP-tidal equilibrium hypothesis, which predicts that low mass ratio binaries
survive for a significantly longer period of time than high mass ratio systems.


title:
An Involution on Involutions and a Generalization of Layered
  Permutations

abstract:
  Taking transposes of Standard Young Tableaux defines a natural involution on
the set $I(n)$ of involutions of length $n$ via the the Robinson-Schensted
correspondence. In some cases, this involution can be defined without resorting
to the Robinson-Schensted correspondence. As a byproduct, we get an interesting
generalization of layered permutations.


title:
Application of a Theory and Simulation based Convective Boundary Mixing
  model for AGB Star Evolution and Nucleosynthesis

abstract:
  The $s$-process nucleosynthesis in Asymptotic Giant Branch (AGB) stars
depends on the modeling of convective boundaries. We present models and
s-process simulations that adopt a treatment of convective boundaries based on
the results of hydrodynamic simulations and on the theory of mixing due to
gravity waves in the vicinity of convective boundaries. Hydrodynamics
simulations suggest the presence of convective boundary mixing (CBM) at the
bottom of the thermal pulse-driven convective zone. Similarly,
convection-induced mixing processes are proposed for the mixing below the
convective envelope during third dredge-up where the 13C pocket for the s
process in AGB stars forms. In this work we apply a CBM model motivated by
simulations and theory to models with initial mass $M = 2$ and $M = 3M_\odot$,
and with initial metal content Z = 0.01 and Z = 0.02. As reported previously,
the He-intershell abundance of 12C and 16O are increased by CBM at the bottom
of pulse-driven convection zone. This mixing is affecting the
$^{22}Ne(\alpha,n)^{25}Mg$ activation and the s-process effciency in the
13C-pocket. In our model CBM at the bottom of the convective envelope during
the third dredgeup represents gravity wave mixing. We take further into account
that hydrodynamic simulations indicate a declining mixing efficiency already
about a pressure scale height from the convective boundaries, compared to
mixing-length theory. We obtain the formation of the 13C-pocket with a mass of
$\approx 10^{-4}M_\odot$. The final $s$-process abundances are characterized by
0.36 < [s=Fe] < 0.78 and the heavy-to-light s-process ratio is 0.23 < [hs=ls] <
0.45. Finally, we compare our results with stellar observations, pre-solar
grain measurements and previous work.


title: Recent results on anisotropic flow and related phenomena in ALICE

abstract:
  The exploration of properties of an extreme state of matter, the Quark--Gluon
Plasma, has broken new ground with the recent Run 2 operation of the Large
Hadron Collider with heavy-ion collisions at the highest energy to date. With
the heavy-ion data taken at the end of 2015, the ALICE Collaboration has made
the first observation of anisotropic flow of charged particles and related
phenomena in lead--lead collisions at the record breaking energy of 5.02 TeV
per nucleon pair. The Run 2 results come after the proton-lead collisions,
which provided a lot of unexpected results obtained with two- and
multi-particle correlation techniques. In these proceedings, a brief overview
of these results will be shown. We will discuss how they further enlighten the
properties of matter produced in ultrarelativistic nuclear collisions. We
indicate the possibility that, to leading order, the striking universality of
flow results obtained with correlation techniques in pp, p--A and A--A
collisions might have purely mathematical origin, and that physical conclusions
therefore could be drawn only from the subleading orders.


title:
Bringing "The Moth" to Light: A Planet-Sculpting Scenario for the HD
  61005 Debris Disk

abstract:
  The HD 61005 debris disk ("The Moth") stands out from the growing collection
of spatially resolved circumstellar disks by virtue of its unusual swept-back
morphology, brightness asymmetries, and dust ring offset. Despite several
suggestions for the physical mechanisms creating these features, no definitive
answer has been found. In this work, we demonstrate the plausibility of a
scenario in which the disk material is shaped dynamically by an eccentric,
inclined planet. We present new Keck NIRC2 scattered-light angular differential
imaging of the disk at 1.2-2.3 microns that further constrains its outer
morphology (projected separations of 27-135 AU). We also present complementary
Gemini Planet Imager 1.6 micron total intensity and polarized light detections
that probe down to projected separations less than 10 AU. To test our
planet-sculpting hypothesis, we employed secular perturbation theory to
construct parent body and dust distributions that informed scattered-light
models. We found that this method produced models with morphological and
photometric features similar to those seen in the data, supporting the premise
of a planet-perturbed disk. Briefly, our results indicate a disk parent body
population with a semimajor axis of 40-52 AU and an interior planet with an
eccentricity of at least 0.2. Many permutations of planet mass and semimajor
axis are allowed, ranging from an Earth mass at 35 AU to a Jupiter mass at 5
AU.


title: Semi-hyperbolic maps are rare

abstract:
  We prove in this paper that the set of semi-hyperbolic rational maps has
Lebesgue measure zero in the space of rational maps of the Riemann sphere for a
fixed degree d at least 2. It generalises an earlier result by J. Graczyk and
the author who proved the same thing in degree 2.


title: Uncertainties in AGB Evolution and Nucleosynthesis

abstract:
  We summarise the evolution and nucleosynthesis in AGB and Super-AGB stars. We
then examine the major sources of uncertainty, especially mass-loss.


title: The uniform content of partial and linear orders

abstract:
  The principle $ADS$ asserts that every linear order on $\omega$ has an
infinite ascending or descending sequence. This has been studied extensively in
the reverse mathematics literature, beginning with the work of Hirschfeldt and
Shore. We introduce the principle $ADC$, which asserts that linear order has an
infinite ascending or descending chain. The two are easily seen to be
equivalent over the base system $RCA_0$ of second order arithmetic; they are
even computably equivalent. However, we prove that $ADC$ is strictly weaker
than $ADS$ under Weihrauch (uniform) reducibility. In fact, we show that even
the principle $SADS$, which is the restriction of $ADS$ to linear orders of
type $\omega + \omega^*$, is not Weihrauch reducible to $ADC$. In this
connection, we define a more natural stable form of $ADS$ that we call
$General\text-SADS$, which is the restriction of $ADS$ to linear orders of type
$k + \omega$, $\omega + \omega^*$, or $\omega + k$, where $k$ is a finite
number. We define $GeneralSADC$ analogously. We prove that $GeneralSADC$ is not
Weihrauch reducible to $SADS$, and so in particular, each of $SADS$ and $SADC$
is strictly weaker under Weihrauch reducibility than its general version.
Finally, we turn to the principle $CAC$, which asserts that every partial order
on $\omega$ has an infinite chain or antichain. This has two previously studied
stable variants, $SCAC$ and $WSCAC$, which were introduced by Hirschfeldt and
Jockusch, and by Jockusch, Kastermans, Lempp, Lerman, and Solomon,
respectively, and which are known to be equivalent over $RCA_0$. Here, we show
that $SCAC$ is strictly weaker than $WSCAC$ under even computable reducibility.


title:
Harnack inequality for the fractional nonlocal linearized
  Monge--Amp\`ere equation

abstract:
  The fractional nonlocal linearized Monge--Amp\`ere equation is introduced. A
Harnack inequality for nonnegative solutions to the Poisson problem on
Monge--Amp\`ere sections is proved.


title:
Topology and geometry cannot be measured by an operator measurement in
  quantum gravity

abstract:
  In the context of LLM geometries, we show that superpositions of classical
coherent states of trivial topology can give rise to new classical limits where
the topology of spacetime has changed. We argue that this phenomenon implies
that neither the topology nor the geometry of spacetime can be the result of an
operator measurement. We address how to reconcile these statements with the
usual semiclassical analysis of low energy effective field theory for gravity.


title:
Combining Density and Overlap (CoDO): A New Method for Assessing the
  Significance of Overlap Among Subgraphs

abstract:
  Algorithms for detecting clusters (including overlapping clusters) in graphs
have received significant attention in the research community. A closely
related important aspect of the problem -- quantification of statistical
significance of overlap of clusters, remains relatively unexplored. This paper
presents the first theoretical and practical results on quantifying
statistically significant interactions between clusters in networks. Such
problems commonly arise in diverse applications, ranging from social network
analysis to systems biology. The paper addresses the problem of quantifying the
statistical significance of the observed overlap of the two clusters in an
Erd\H{o}s-R\'enyi graph model. The analytical framework presented in the paper
assigns a $p$-value to overlapping subgraphs by combining information about
both the sizes of the subgraphs and their edge densities in comparison to the
corresponding values for their overlapping component. This $p$-value is
demonstrated to have excellent discrimination properties in real applications
and is shown to be robust across broad parameter ranges.
  Our results are comprehensively validated on synthetic, social, and
biological networks. We show that our framework: (i) derives insight from both
the density and the size of overlap among communities (circles/pathways), (ii)
consistently outperforms state-of-the-art methods over all tested datasets, and
(iii) when compared to other measures, has much broader application scope. In
the context of social networks, we identify highly interdependent (social)
circles and show that our predictions are highly co-enriched with known user
features. In networks of biomolecular interactions, we show that our method
identifies novel cross-talk between pathways, sheds light on their mechanisms
of interaction, and provides new opportunities for investigations of
biomolecular interactions.


title:
Measurement of the inclusive $t\bar{t}$ production cross section in
  $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV and determination of the top
  quark pole mass

abstract:
  The inclusive cross section of top quark-antiquark pairs produced in
$p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV is measured in the lepton$+$jets
and dilepton decay channels. The data sample corresponds to 9.7 fb${}^{-1}$ of
integrated luminosity recorded with the D0 detector during Run II of the
Fermilab Tevatron Collider. Employing multivariate analysis techniques we
measure the cross section in the two decay channels and we perform a combined
cross section measurement. For a top quark mass of 172.5 GeV, we measure a
combined inclusive top quark-antiquark pair production cross section of
$\sigma_{t\bar{t}} = 7.26 \pm
0.13\,(\mathrm{stat.})\,^{+0.57}_{-0.50}\,(\mathrm{syst.})$ pb which is
consistent with standard model predictions. We also perform a likelihood fit to
the measured and predicted top quark mass dependence of the inclusive cross
section, which yields a measurement of the pole mass of the top quark. The
extracted value is $m_t = 172.8 \pm
1.1\,(\mathrm{theo.})\,^{+3.3}_{-3.1}\,(\mathrm{exp.})$ GeV.


title:
A search for flavor-changing non-standard neutrino interactions using
  $\nu_{e}$ appearance in MINOS

abstract:
  We report new constraints on flavor-changing non-standard neutrino
interactions from the MINOS long-baseline experiment using $\nu_{e}$ and
$\bar{\nu}_{e}$ appearance candidate events from predominantly $\nu_{\mu}$ and
$\bar{\nu}_{\mu}$ beams. We used a statistical selection algorithm to separate
$\nu_{e}$ candidates from background events, enabling an analysis of the
combined MINOS neutrino and antineutrino data. We observe no deviations from
standard neutrino mixing, and thus place constraints on the non-standard
interaction matter effect, $|\varepsilon_{e\tau}|$, and phase,
$(\delta_{CP}+\delta_{e\tau})$, using a thirty-bin likelihood fit.


title: Evaluation System for a Bayesian Optimization Service

abstract:
  Bayesian optimization is an elegant solution to the hyperparameter
optimization problem in machine learning. Building a reliable and robust
Bayesian optimization service requires careful testing methodology and sound
statistical analysis. In this talk we will outline our development of an
evaluation framework to rigorously test and measure the impact of changes to
the SigOpt optimization service. We present an overview of our evaluation
system and discuss how this framework empowers our research engineers to
confidently and quickly make changes to our core optimization engine


title:
Field-measure correspondence in Liouville quantum gravity almost surely
  commutes with all conformal maps simultaneously

abstract:
  In Liouville quantum gravity (or $2d$-Gaussian multiplicative chaos) one
seeks to define a measure $\mu^h = e^{\gamma h(z)} dz$ where $h$ is an instance
of the Gaussian free field on a planar domain $D$. Since $h$ is a distribution,
not a function, one needs a regularization procedure to make this precise: for
example, one may let $h_\epsilon(z)$ be the average value of $h$ on the circle
of radius $\epsilon$ centered at $z$ (or an analogous average defined using a
bump function supported inside that circle) and then write $\mu^h =
\lim_{\epsilon \to 0} \epsilon^{\frac{\gamma^2}{2}} e^{\gamma h_\epsilon(z)}
dz$.
  If $\phi: \tilde D \to D$ is a conformal map, one can write $\tilde h = h
\circ \phi + Q \log |\phi'|$, where $Q = 2/\gamma + \gamma/2$. The measure
$\mu^{\tilde h}$ on $\tilde D$ is then a.s.\ equivalent to the pullback via
$\phi^{-1}$ of the measure $\mu^h$ on $D$. Interestingly, although this a.s.\
holds for each \textit{given} $\phi$, nobody has ever proved that it a.s.\
holds \textit {simultaneously} for all possible $\phi$. We will prove that this
is indeed the case. This is conceptually important because one frequently
defines a \textit{quantum surface} to be an equivalence class of pairs $(D, h)$
(where pairs such as the $(D,h)$ and $(\tilde D, \tilde h)$ above are
considered equivalent) and it is useful to know that the set of pairs
$(D,\mu^{h})$ obtained from the set of pairs $(D,h)$ in an equivalence class is
itself an equivalence class with respect to the usual measure pullback
relation.


title: Avoiding rainbow induced subgraphs in vertex-colorings

abstract:
  For a fixed graph $H$ on $k$ vertices, and a graph $G$ on at least $k$
vertices, we write $G\rightarrow H$ if in any vertex-coloring of $G$ with $k$
colors, there is an induced subgraph isomorphic to $H$ whose vertices have
distinct colors. In other words, if $G\rightarrow H$ then a totally
multicolored induced copy of $H$ is unavoidable in any vertex-coloring of $G$
with $k$ colors. In this paper, we show that, with a few notable exceptions,
for any graph $H$ on $k$ vertices and for any graph $G$ which is not isomorphic
to $H$, $G\not\!\rightarrow H$. We explicitly describe all exceptional cases.
This determines the induced vertex-anti-Ramsey number for all graphs and shows
that totally multicolored induced subgraphs are, in most cases, easily
avoidable.


title: A treecode to simulate dust-plasma interactions

abstract:
  The interaction of a small object with surrounding plasma is an area of
plasma-physics research with a multitude of applications. This paper introduces
the plasma octree code pot, a microscopic simulator of a spheroidal dust grain
in a plasma. pot uses the Barnes-Hut treecode algorithm to perform $N$-body
simulations of electrons and ions in the vicinity of a chargeable spheroid,
employing also the Boris particle-motion integrator and Hutchinson's
reinjection algorithm from SCEPTIC; a description of the implementation of all
three algorithms is provided. We present results from pot simulations of the
charging of spheres in magnetized plasmas, and of spheroids in unmagnetized
plasmas. The results call into question the validity of using the Boltzmann
relation in hybrid PIC codes.


title:
Experimental and Numerical Investigation of Intra-Laminar Energy
  Dissipation and Size Effect in Two-Dimensional Textile Composites

abstract:
  Design of large composite structures requires understanding the scaling of
their mechanical properties, an aspect often overlooked in the literature on
composites. This contribution analyzes, experimentally and numerically, the
intra-laminar size effect of textile composite structures. Test results of
geometrically similar Single Edge Notched specimens made of 8 layers of 0
degree epoxy/carbon twill 2 by 2 laminates are reported. Results show that the
nominal strength decreases with increasing specimen size and that the
experimental data can be fitted well by Bazant's size effect law, allowing an
accurate identification of the intra-laminar fracture energy of the material.
The importance of an accurate estimation of Gf in situations where
intra-laminar fracturing is the main energy dissipation mechanism is clarified
by studying numerically its effect on crashworthiness of composite tubes.
Simulations demonstrate that, for the analyzed geometry, a decrease of the
fracture energy to 50% of the measured value corresponds to an almost 42%
decrease in plateau crushing load. Further, assuming a vertical stress drop
after the peak, a typical assumption of strength-based constitutive laws
implemented in most commercial Finite Element codes, results in an strength
underestimation of the order of 70%. The main conclusion of this study is that
measuring accurately fracture energy and modeling correctly the fracturing
behavior of textile composites, including their quasi-brittleness, is key. This
can be accomplished neither by strength- or strain-based approaches, which
neglect size effect, nor by LEFM which does not account for the finiteness of
the Fracture Process Zone.


title:
Inverse design of third-order Dirac exceptional points in photonic
  crystals

abstract:
  We propose a novel inverse-design method that enables brute-force discovery
of photonic crystal (PhC) structures with complex spectral degeneracies. As a
proof of principle, we demonstrate PhCs exhibiting third-order Dirac points
formed by the \emph{accidental} degeneracy of modes of monopolar, dipolar, and
quadrupolar nature. We show that under suitable conditions, these modes can
coalesce and form a third-order exceptional point (EP3), leading to diverging
Petermann factors. We show that the spontaneous emission (SE) rate of emitters
at such EP3s, related to the local density of states, can be enhanced by a
factor of 8 in purely lossy (passive) structures, with larger enhancements
$\sim \sqrt{n^3}$ possible at exceptional points of higher order $n$ or in
materials with gain.


title:
The genealogy of Maria de Aguilar: evidence of admixture in the early
  Spanish Colony in Costa Rica

abstract:
  During long time, historians and genealogists have interpreted that the elite
that emerged during the Spanish Conquest was almost exclusively European. We
reconstructed a deep matrilineal genealogy which includes recent Costa Rican
ex-presidents and religious authorities back to their ancestors at the early
17th century, and compared their historic ethnic affinities with genetic
mitochondrial evidence of some living descendents. The observed DNA lineage has
an Amerindian ancestry. Such results point out that an Amerindian gene flow had
occurred into the Spanish group during the first generations of colonial
society. This conclusion do not support the current idea that the Spanish elite
avoided interethnic marriages.


title:
Fine-Grained Classification of Pedestrians in Video: Benchmark and State
  of the Art

abstract:
  A video dataset that is designed to study fine-grained categorisation of
pedestrians is introduced. Pedestrians were recorded "in-the-wild" from a
moving vehicle. Annotations include bounding boxes, tracks, 14 keypoints with
occlusion information and the fine-grained categories of age (5 classes), sex
(2 classes), weight (3 classes) and clothing style (4 classes). There are a
total of 27,454 bounding box and pose labels across 4222 tracks. This dataset
is designed to train and test algorithms for fine-grained categorisation of
people, it is also useful for benchmarking tracking, detection and pose
estimation of pedestrians. State-of-the-art algorithms for fine-grained
classification and pose estimation were tested using the dataset and the
results are reported as a useful performance baseline.


title:
Lattice Discrete Particle Model (LDPM) for pressure-dependent
  inelasticity in granular rocks

abstract:
  This paper deals with the formulation, calibration, and validation of a
Lattice Discrete Particle Model (LDPM) for the simulation of the
pressure-dependent inelastic response of granular rocks. LDPM is formulated in
the framework of discrete mechanics and it simulates the heterogeneous
deformation of cemented granular systems by means of discrete
compatibility/equilibrium equations defined at the grain scale. A numerical
strategy is proposed to generate a realistic microstructure based on the actual
grain size distribution of a sandstone and the capabilities of the method are
illustrated with reference to the particular case of Bleurswiller sandstone,
i.e. a granular rock that has been extensively studied at the laboratory scale.
LDPM micromechanical parameters are calibrated based on evidences from triaxial
experiments, such as hydrostatic compression, brittle failure at low
confinement and plastic behavior at high confinement. Results show that LDPM
allows exploring the effect of fine-scale heterogeneity on the inelastic
response of rock cores, achieving excellent quantitative performance across a
wide range of stress conditions. In addition, LDPM simulations demonstrate its
capability of capturing different modes of strain localization within a unified
mechanical framework, which makes this approach applicable for a wide variety
of geomechanical settings. Such promising performance suggests that LDPM may
constitute a viable alternative to existing discrete numerical methods for
granular rocks, as well as a versatile tool for the interpretation of their
complex deformation/failure patterns and for the development of continuum
models capturing the effect of micro-scale heterogeneity.


title:
High-frequency behavior of FeN thin films fabricated by reactive
  sputtering

abstract:
  We investigated high-frequency behavior of FeN thin films prepared by
reactive sputtering through ferromagnetic resonance (FMR) and its relationship
with the static magnetic properties. The FMR was observed in the frequency
range from 2 to 18 GHz in the FeN films fabricated at proper nitrogen flow rate
(NFR). In those FeN thin films, a decrease of the saturation magnetization and
the corresponding decrease of the FMR frequency were observed as NFR was
increased during the deposition. The external field dependences of the FMR
frequencies were well fit to the Kittel formula and the Land\'e g-factors
determined from the fit were found to be very close to the free electron value.
The high-field damping parameters were almost insensitive to the growth
condition of NFR. However, the low-field damping parameters exhibited high
sensitivity to NFR very similar to the dependence of the hard-axis coercivity
on NFR, suggesting that extrinsic material properties such as impurities and
defect structures could be important in deciding the low-field damping
behavior.


title:
Modeling and performance evaluation of stealthy false data injection
  attacks on smart grid in the presence of corrupted measurements

abstract:
  The false data injection (FDI) attack cannot be detected by the traditional
anomaly detection techniques used in the energy system state estimators. In
this paper, we demonstrate how FDI attacks can be constructed blindly, i.e.,
without system knowledge, including topological connectivity and line reactance
information. Our analysis reveals that existing FDI attacks become detectable
(consequently unsuccessful) by the state estimator if the data contains grossly
corrupted measurements such as device malfunction and communication errors. The
proposed sparse optimization based stealthy attacks construction strategy
overcomes this limitation by separating the gross errors from the measurement
matrix. Extensive theoretical modeling and experimental evaluation show that
the proposed technique performs more stealthily (has less relative error) and
efficiently (fast enough to maintain time requirement) compared to other
methods on IEEE benchmark test systems.


title:
Variational hybridization and transformation for large inaccurate
  noisy-or networks

abstract:
  Variational inference provides approximations to the computationally
intractable posterior distribution in Bayesian networks. A prominent medical
application of noisy-or Bayesian network is to infer potential diseases given
observed symptoms. Previous studies focus on approximating a handful of
complicated pathological cases using variational transformation. Our goal is to
use variational transformation as part of a novel hybridized inference for
serving reliable and real time diagnosis at web scale. We propose a hybridized
inference that allows variational parameters to be estimated without disease
posteriors or priors, making the inference faster and much of its computation
recyclable. In addition, we propose a transformation ranking algorithm that is
very stable to large variances in network prior probabilities, a common issue
that arises in medical applications of Bayesian networks. In experiments, we
perform comparative study on a large real life medical network and scalability
study on a much larger (36,000x) synthesized network.


title:
Dimensionality Reduction on SPD Manifolds: The Emergence of
  Geometry-Aware Methods

abstract:
  Representing images and videos with Symmetric Positive Definite (SPD)
matrices, and considering the Riemannian geometry of the resulting space, has
been shown to yield high discriminative power in many visual recognition tasks.
Unfortunately, computation on the Riemannian manifold of SPD matrices
-especially of high-dimensional ones- comes at a high cost that limits the
applicability of existing techniques. In this paper, we introduce algorithms
able to handle high-dimensional SPD matrices by constructing a
lower-dimensional SPD manifold. To this end, we propose to model the mapping
from the high-dimensional SPD manifold to the low-dimensional one with an
orthonormal projection. This lets us formulate dimensionality reduction as the
problem of finding a projection that yields a low-dimensional manifold either
with maximum discriminative power in the supervised scenario, or with maximum
variance of the data in the unsupervised one. We show that learning can be
expressed as an optimization problem on a Grassmann manifold and discuss fast
solutions for special cases. Our evaluation on several classification tasks
evidences that our approach leads to a significant accuracy gain over
state-of-the-art methods.


title:
On Polynomial Time Approximation Bounded Solution for TSP and NP
  Complete Problems

abstract:
  The question of whether all problems in NP class are also in P class is
generally considered one of the most important open questions in mathematics
and theoretical computer science as it has far-reaching consequences to other
problems in mathematics, computer science, biology, philosophy and
cryptography. There are intensive research on proving `NP not equal to P' and
`NP equals to P'. However, none of the `proved' results is commonly accepted by
the research community up to date. In this paper, motived by approximability of
traveling salesman problem (TSP) in polynomial time, we aim to provide a new
perspective: showing that NP=P from polynomial time approximation-bounded
solutions of TSP in Euclidean space.


title: Conformal Blocks in type C at level one

abstract:
  We investigate the behavior of vector bundles of conformal blocks for
$sp_{2\ell}$ at level one on $\bar{M}_{0,n}$. We show their first Chern classes
are equivalent to conformal blocks divisors for $sl_2$ at level $\ell$ if and
only if the corresponding vector bundles have rank one or zero, and all become
equal when the Lie algebra $\ell$ is large enough. As a consequence of these
results, we conclude the cone generated by these divisors is polyhedral.


title: The Generality of a Section of a Curve

abstract:
  Let f: C --> P^3 be a general curve of genus g, mapped to P^3 via a general
linear series of degree d; and let Q be a general (and thus smooth) quadric. In
this paper, we show that the points of intersection f(C) \cap Q give a general
collection of 2d points on Q, except for exactly six exceptional cases. We also
prove similar theorems for every other pair (r, n) for which, except for only
finitely many pairs (d, g), the intersection of a general curve of genus g
mapped to P^r via a general linear series of degree d, with a general
hypersurface S of degree n, is a general collection of dn points on S.
  As explained in arXiv:1809.05980, these results play a key role in the
author's proof of the Maximal Rank Conjecture


title:
A centrosymmetric hexagonal magnet with superstable biskyrmion magnetic
  nanodomains in a wide temperature range of 100K to 340K

abstract:
  Here, we report on the experimental discovery of biskyrmion magnetic
nanodomains at RT and the observation of a biskyrmion-derived topological Hall
effect (THE) in the centrosymmetric hexagonal MnNiGa magnet. Using a phase
reconstruction technique based on a transport-of-intensity equation (TIE), we
established the texture of the biskyrmion spin. Results from Lorentz
transmission electron microscopy (TEM) and the topological Hall effect revealed
that the biskyrmion phase is stable over a much wider temperature range (100 K
to ~340K) and a larger magnetic field range in our material than in
skyrmion-hosting bulk crystals reported previously[1-3,6]. The super-wide
operating temperature and the broad range of material options indicate
important progress toward the realization of skyrmion-based spintronic devices.


title:
Planelike interfaces in long-range Ising models and connections with
  nonlocal minimal surfaces

abstract:
  This paper contains three types of results:
  1. the construction of ground state solutions for a long-range Ising model
whose interfaces stay at a bounded distance from any given hyperplane,
  2. the construction of nonlocal minimal surfaces which stay at a bounded
distance from any given hyperplane,
  3. the reciprocal approximation of ground states for long-range Ising models
and nonlocal minimal surfaces.
  In particular, we establish the existence of ground state solutions for
long-range Ising models with planelike interfaces, which possess scale
invariant properties with respect to the periodicity size of the environment.
The range of interaction of the Hamiltonian is not necessarily assumed to be
finite and also polynomial tails are taken into account (i.e. particles can
interact even if they are very far apart the one from the other).
  In addition, we provide a rigorous bridge between the theory of long-range
Ising models and that of nonlocal minimal surfaces, via some precise limit
result.


title: On weighted Ramsey numbers

abstract:
  The weighted Ramsey number, ${\rm wR}(n,k)$, is the minimum $q$ such that
there is an assignment of nonnegative real numbers (weights) to the edges of
$K_n$ with the total sum of the weights equal to ${n\choose 2}$ and there is a
Red/Blue coloring of edges of the same $K_n$, such that in any complete
$k$-vertex subgraph $H$, of $K_n$, the sum of the weights on Red edges in $H$
is at most $q$ and the sum of the weights on Blue edges in $H$ is at most $q$.
This concept was introduced recently by Fujisawa and Ota.
  We provide new bounds on ${\rm wR}(n,k)$, for $k\geq 4$ and $n$ large enough
and show that determining ${\rm wR}(n,3)$ is asymptotically equivalent to the
problem of finding the fractional packing number of monochromatic triangles in
colorings of edges of complete graphs with two colors.