title:
Constraining heavy axion-like particles by energy deposition in Globular
  Cluster stars

abstract:
  Heavy axion-like particles (ALPs), with masses up to a few 100 keV and
coupled with photons can be efficiently produced in stellar plasmas,
contributing to a significant energy-loss. This argument has been applied to
helium burning stars in Globular Clusters (GCs) to obtain stringent bounds on
the ALP-photon coupling $g_{a\gamma}$. However, for sufficiently large values
of the ALP mass and coupling to photons, one should expect a significant
fraction of ALPs to decay inside the star. These ALPs do not contribute to the
energy loss but rather lead to an efficient energy transfer inside the star. We
present a new ballistic recipe that covers both the energy-loss and
energy-transfer regimes and we perform the first dedicated simulation of GC
stars including the ALP energy transfer. This argument allows us to constrain
ALPs with $m_a \lesssim 0.4$ MeV and $g_{a\gamma} \simeq 10^{-5}$ GeV$^{-1}$,
probing a section of the ALP parameter space informally known as "cosmological
triangle". This region is particularly interesting since it has been excluded
only using standard cosmological arguments that can be evaded in nonstandard
scenarios.


title:
Dynamical quantum phase transitions in spin-$S$ $\mathrm{U}(1)$ quantum
  link models

abstract:
  Dynamical quantum phase transitions (DQPTs) are a powerful concept of probing
far-from-equilibrium criticality in quantum many-body systems. With the strong
ongoing experimental drive to quantum-simulate lattice gauge theories, it
becomes important to investigate DQPTs in these models in order to better
understand their far-from-equilibrium properties. In this work, we use infinite
matrix product state techniques to study DQPTs in spin-$S$ $\mathrm{U}(1)$
quantum link models. Although we are able to reproduce literature results
directly connecting DQPTs to a sign change in the dynamical order parameter in
the case of $S=1/2$ for quenches starting in a vacuum initial state, we find
that for different quench protocols or different values of the link spin length
$S>1/2$ this direct connection is no longer present. In particular, we find
that there is an abundance of different types of DQPTs not directly associated
with any sign change of the order parameter. Our findings indicate that DQPTs
are fundamentally different between the Wilson--Kogut--Susskind limit and its
representation through the quantum link formalism.

categories: cond-mat.str-el cond-mat.quant-gas hep-lat quant-ph


title: Disorder-free localization with Stark gauge protection

abstract:
  Disorder-free localization in translation-invariant gauge theories presents a
counterintuitive yet powerful framework of ergodicity breaking in quantum
many-body physics. The fragility of this phenomenon in the presence of
gauge-breaking errors has recently been addressed, but no scheme has been able
to reliably stabilize disorder-free localization through all accessible
evolution times while preserving the disorder-free property. Here, we introduce
the concept of \textit{Stark gauge protection}, which entails a linear sum in
gauge-symmetry local (pseudo)generators weighted by a Stark potential. Using
exact diagonalization and Krylov-based methods, we show how this scheme can
stabilize or even enhance disorder-free localization against gauge-breaking
errors in $\mathrm{U}(1)$ and $\mathbb{Z}_2$ gauge theories up to all
accessible evolution times, without inducing \textit{bona fide} Stark many-body
localization. We show through a Magnus expansion that the dynamics under Stark
gauge protection is described by an effective Hamiltonian where gauge-breaking
terms are suppressed locally by the protection strength and additionally by the
matter site index, which we argue is the main reason behind stabilizing the
localization up to all accessible times. Our scheme is readily feasible in
modern ultracold-atom experiments and Rydberg-atom setups with optical
tweezers.

categories: cond-mat.quant-gas cond-mat.dis-nn cond-mat.str-el quant-ph


title:
H$\alpha$ Morphologies of Star Clusters in 16 LEGUS Galaxies:
  Constraints on HII region evolution timescales

abstract:
  The analysis of star cluster ages in tandem with the morphology of their HII
regions can provide insight into the processes that clear a cluster's natal
gas, as well as the accuracy of cluster ages and dust reddening derived from
Spectral Energy Distribution (SED) fitting. We classify 3757 star clusters in
16 nearby galaxies according to their H$\alpha$ morphology (concentrated,
partially exposed, no emission), using Hubble Space Telescope (HST) imaging
from the Legacy ExtraGalactic Ultraviolet Survey (LEGUS). We find: 1) The mean
SED ages of clusters with concentrated (1-2 Myr) and partially exposed HII
region morphologies (2-3 Myr) indicate a relatively early onset of gas clearing
and a short (1-2 Myr) clearing timescale. 2) The reddening of clusters can be
overestimated due to the presence of red supergiants, which is a result of
stochastic sampling of the IMF in low mass clusters. 3) The age-reddening
degeneracy impacts the results of the SED fitting - out of 1408 clusters with
M$_*$ $\geq$ 5000 M$_{\odot}$, we find that at least 46 (3%) have SED ages
which appear significantly underestimated or overestimated based on H$\alpha$
and their environment, while the total percentage of poor age estimates is
expected to be several times larger. 4) Lastly, we examine the dependence of
the morphological classifications on spatial resolution. At HST resolution, our
conclusions are robust to the distance range spanned by the sample (3-10 Mpc).
However, analysis of ground-based H$\alpha$ images shows that compact and
partially exposed morphologies frequently cannot be distinguished from each
other.


title: Is quantum advantage the right goal for quantum machine learning?

abstract:
  Machine learning is frequently listed among the most promising applications
for quantum computing. This is in fact a curious choice: Today's machine
learning algorithms are notoriously powerful in practice, but remain
theoretically difficult to study. Quantum computing, in contrast, does not
offer practical benchmarks on realistic scales, and theory is the main tool we
have to judge whether it could become relevant for a problem. In this
perspective we explain why it is so difficult to say something about the
practical power of quantum computers for machine learning with the tools we are
currently using. We argue that these challenges call for a critical debate on
whether quantum advantage and the narrative of "beating" classical machine
learning should continue to dominate the literature the way it does, and
provide a few examples for alternative research questions.


title:
$E_9$ symmetry in the Heterotic String on $S^1$ and the Weak Gravity
  Conjecture

abstract:
  We show that compactifications of the heterotic string on a circle exhibit at
the boundary of moduli space ($R\to 0$, or equivalently the decompactification
limit $R \to \infty$) a tower of winding or momentum modes that enhance the
$E_8 \times E_8$ or $SO(32)$ gauge symmetry to the affine algebras $(E_9 \oplus
E_9)/\sim$ (the identification means that the two copies of $E_9$ share the
same central extension) and $\hat{D}_{16}$, respectively. We also prove that
these towers of modes satisfy the lattice Weak Gravity and Repulsive Force
Conjectures.


title: Unified Description of Macroscopic Quantum Forces

abstract:
  We introduce a unified description of Casimir and Casimir-Polder forces
between classical objects in quantum field theory (QFT). We focus on
interactions mediated by a scalar field. We first show that the quantum work
felt by an arbitrary (either rigid or deformable) classical body is finite upon
requiring conservation of matter. Using our formulation, we explicitly show how
the complete QFT prediction for the quantum pressure inside the Dirichlet
sphere is finite, thereby solving a long-standing problem. We then show that
our general result interpolates between Casimir and Casimir-Polder forces for
arbitrary rigid bodies. We provide the expressions for the generalised Casimir
force in the simple cases of plate-plate and plate-point geometries. In the
latter geometry, we show how to compute phase shifts observable in atomic
interferometry, induced by the generalized quantum force.


title:
Creating Simple, Interpretable Anomaly Detectors for New Physics in Jet
  Substructure

abstract:
  Anomaly detection with convolutional autoencoders is a popular method to
search for new physics in a model-agnostic manner. These techniques are
powerful, but they are still a "black box," since we do not know what
high-level physical observables determine how anomalous an event is. To address
this, we adapt a recently proposed technique by Faucett et.al., which maps out
the physical observables learned by a neural network classifier, to the case of
anomaly detection. We propose two different strategies that use a small number
of high-level observables to mimic the decisions made by the autoencoder on
background events. Despite the underlying differences in their approach, we
find that both strategies have similar ordering performance as the autoencoder
and independently use the same five high-level observables. From there, we
compare the performance of these networks as anomaly detectors. We find that
both strategies perform similarly to the autoencoder across a variety of
signals, giving a nontrivial demonstration that learning to order background
events transfers to ordering a variety of signal events.


title: Variability Timescales of H$\alpha$ on Active Mid-to-Late M dwarfs

abstract:
  We present a study of the variation timescales of the chromospheric activity
indicator H$\alpha$ on a sample of 13 fully-convective, active mid-to-late M
stars with masses between 0.1--0.3 solar masses. Our goal was to determine the
dominant variability timescale and, by inference, a possible mechanism
responsible for the variation. We gathered 10 or more high-resolution spectra
each of 10 stars using the TRES spectrograph at times chosen to span all phases
of stellar rotation, as determined from photometric data from the MEarth
Observatories. All stars varied in their H$\alpha$ emission. For 9 of these
stars, we found no correlation between H$\alpha$ and rotational phase,
indicating that constant emission from fixed magnetic structures, such as
starspots and plage, are unlikely to be the dominant source of H$\alpha$
emission variability. In contrast, one star, G 7-34, shows a clear relationship
between H$\alpha$ and stellar rotational phase. Intriguingly, we found that
this star is a member of the AB Doradus moving group and hence has the young
age of 149 Myr. High-cadence spectroscopic observations of three additional
stars revealed that they are variable on timescales ranging from 20--45
minutes, which we posit may be due to flaring behavior. For one star, GJ 1111,
simultaneous TESS photometry and spectroscopic monitoring show an increase in
H$\alpha$ emission with increased photometric brightness. We conclude that
low-energy flares are able to produce variation in H$\alpha$ on the timescales
we observe and thus may be the dominant source of H$\alpha$ variability on
active fully-convective M dwarfs.


title:
Big Three Dragons. III: A Study of Molecular Gas in a Bright Lyman-Break
  Galaxy at $z=7.15$ with ALMA

abstract:
  We report ALMA Band 3 observations of CO(6-5), CO(7-6) and [CI](2-1) in
B14-65666 ("Big Three Dragons"), one of the brightest Lyman-Break Galaxies at
$z>7$ in the rest-frame ultraviolet continuum, far-infrared continuum, and
emission lines of [OIII] 88 $\mu$m and [CII] 158 $\mu$m. None of CO(6-5),
CO(7-6) and [CI](2-1) are detected, whose $3\sigma$ upper limits on the
luminosities are about 50 times fainter than the [CII] luminosity. Based on
three methods of i) [CII] luminosity and a [CII]-to-H$_{2}$ conversion factor
reported in local metal-poor dwarf galaxies, ii) a dust mass and
metallicity-dependent dust-to-gas mass ratio, and iii) a dynamical mass
estimate, we obtain the molecular gas mass ($M_{\rm mol}$) to be
$(0.05-11)\times10^{10} M_{\rm \odot}$, which is consistent with its upper
limit inferred from the non-detection of mid-$J$ CO and [CI](2-1). Albeit with
large uncertainty in $M_{\rm mol}$, we estimate a high molecular gas-to-stellar
mass ratio ($\mu_{\rm gas}$) of $0.65-140$ and a short gas depletion time
($t_{\rm dep}$) of $2.5-550$ Myr, which are broadly consistent with
extrapolations of $\mu_{\rm gas}$ and $t_{\rm dep}$ as functions of redshift,
specific-star formation rate, and stellar mass as reported in previous studies.
The short $t_{\rm dep}$ partly reflects the starburst nature of the target,
likely to be induced by a major-merger event. B14-65666 can be an ancestor of a
passive galaxy at $z\gtrsim4$ if no gas is fueled from outside the galaxy.
Overall, our observations highlight difficulty in obtaining robust conclusion
from mid-$J$ CO alone particularly in the epoch of reionization, and motivate
studies that use other tracers as an alternative gas mass tracer.


title:
New Modules for the SEDMachine to Remove Contaminations from Cosmic Rays
  and Non-target Light: BYECR and CONTSEP

abstract:
  Currently time-domain astronomy can scan the entire sky on a daily basis,
discovering thousands of interesting transients every night. Classifying the
ever-increasing number of new transients is one of the main challenges for the
astronomical community. One solution that addresses this issue is the
robotically controlled Spectral Energy Distribution Machine (SEDM) which
supports the Zwicky Transient Facility (ZTF). SEDM with its pipeline PYSEDM
demonstrates that real-time robotic spectroscopic classification is feasible.
In an effort to improve the quality of the current SEDM data, we present here
two new modules, BYECR and CONTSEP. The first removes contamination from cosmic
rays, and the second removes contamination from non-target light. These new
modules are part of the automated PYSEDM pipeline and fully integrated with the
whole process. Employing BYECR and CONTSEP modules together automatically
extracts more spectra than the current PYSEDM pipeline. Using SNID
classification results, the new modules show an improvement in the
classification rate and accuracy of 2.8% and 1.7%, respectively, while the
strength of the cross-correlation remains the same. Improvements to the SEDM
astrometry would further boost the improvement of the CONTSEP module. This kind
of robotic follow-up with a fully automated pipeline has the potential to
provide the spectroscopic classifications for the transients discovered by ZTF
and also by the Rubin Observatory's Legacy Survey of Space and Time.


title:
Modelling X-shaped Radio Galaxies: Dynamical and Emission Signatures
  from the Back-flow model

abstract:
  Some of the radio galaxies show distortion in their jets, forming tailed or
winged sources. X-shaped radio galaxies are a subclass of winged sources
formation mechanism of which is still unclear. The focus of this work is to
understand hydro-dynamical back-flows and their role in dynamics and
non-thermal emission signatures (in presence of radiative losses and diffusive
shock acceleration) during the initial phase of these galaxies. We have
performed relativistic MHD simulations of an under-dense jet travelling in a
tri-axial ambient using a hybrid Eulerian-Lagrangian framework to incorporate
effects of micro-physical processes. We have demonstrated the dominant role
played by pressure gradient in shaping XRGs in thermally dominated cases. We
show that the prominence of the formed structure decreases as the jet deviates
from the major axis of the ambient. The wing evolution is mainly governed by
re-energized particles due to shocks that keep the structure active during the
evolution time. The synthetic intensity maps of the radio galaxy show
similarities with morphologies that are typically found in observed XRGs. This
includes the cases with wider wings than the active lobes. The characteristic
emission signatures in terms of its synchrotron spectra and implication of
equipartition condition in age estimation are also discussed here.
Additionally, we show that discrepancy of age can be attributed to mixing of
different aged particle populations. Further, the effect of viewing angle on
the difference of spectral index of the active lobes and the wings $(\Delta
\alpha)$ shows a large variation and degenerate behaviour. We have demonstrated
the role of diffusive shocks in the obtained variation and have concluded that
the spread of $(\Delta \alpha)$ is not a dependable characteristic in
determining the formation model of XRGs.


title: Single-shot quantum measurements sketch quantum states

abstract:
  Quantum measurements are our eyes to the quantum systems consisting of a
multitude of microscopic degrees of freedom. However, the intrinsic uncertainty
of quantum measurements and the exponentially large Hilbert space pose natural
barriers to simple interpretations of the measurement outcomes. We propose a
nonlinear "measurement energy" based upon the measurement outcomes and an
iterative effective-Hamiltonian approach to extract the most probable states
(maximum likelihood estimates) in an efficient and general fashion, thus
reconciling the non-commuting observables and getting more out of the quantum
measurements. We showcase the versatility and accuracy of our perspective on
random long-range fermion models and Kitaev quantum spin liquid models, where
smoking-gun signatures were lacking. Our study also paves the way towards
concepts such as nonlinear-operator Hamiltonian and applications such as parent
Hamiltonian reconstruction.


title:
HST WFC3/Grism Observations of the Candidate Ultra-High-Redshift Radio
  Galaxy GLEAM J0917-0012

abstract:
  We present Hubble Space Telescope Wide Field Camera 3 photometric and grism
observations of the candidate ultra-high-redshift (z>7) radio galaxy, GLEAM
J0917-0012. This radio source was selected due to the curvature in its 70-230
MHz, low-frequency Murchison Widefield Array radio spectrum and its faintness
in K-band. Follow-up spectroscopic observations of this source with the VLA and
ALMA were inconclusive as to its redshift. Our F105W and F0986M imaging
observations detect the host of GLEAM J0917-0012 and a companion galaxy, ~one
arcsec away. The G102 grism observations reveal a single weak line in each of
the spectra of the host and the companion. To help identify these lines we
utilised several photometric redshift techniques including template fitting to
the grism spectra, fitting the UV-to-radio photometry with galaxy templates
plus a synchrotron model, fitting of the UV-to-near-infrared photometry with
EAZY, and fitting the radio data alone with RAiSERed. For the host of GLEAM
J0917-0012 we find a line at 1.12 micron and the UV-to-radio spectral energy
distribution fitting favours solutions at z~2 or z~8. While this fitting shows
a weak preference for the lower redshift solution, the models from the higher
redshift solution are more consistent with the strength of the spectral line.
The redshift constraint by RAiSERed of z>6.5 also supports the interpretation
that this line could be Lyman-alpha at z=8.21; however EAZY favours the z~2
solution. We discuss the implications of both solutions. For the companion
galaxy we find a line at 0.98 micron and the spectral energy distribution
fitting favours solutions at z<3 implying that the line could be the [OII]3727
doublet at z=1.63 (although the EAZY solution is z~2.6+/-0.5). Further
observations are still required to unambiguously determine the redshift of this
intriguing candidate ultra-high-redshift radio galaxy (abridged).


title: Partisan Asymmetries in Exposure to Misinformation

abstract:
  Health misinformation is believed to have contributed to vaccine hesitancy
during the Covid-19 pandemic, highlighting concerns about the role of social
media in polarization and social stability. While previous research has
identified a link between political partisanship and misinformation sharing
online, the interaction between partisanship and how much misinformation people
see within their social networks has not been well studied. As a result, we do
not know whether partisanship drives exposure to misinformation or people
selectively share misinformation despite being exposed to factual content. We
study Twitter discussions about the Covid-19 pandemic, classifying users
ideologically along political and factual dimensions. We find partisan
asymmetries in both sharing behaviors and exposure, with conservatives more
likely to see and share misinformation and moderate liberals seeing the most
factual content. We identify multi-dimensional echo chambers that expose users
to ideologically congruent content; however, the interaction between political
and factual dimensions creates conditions for the highly polarized users --
hardline conservatives and liberals -- to amplify misinformation. Despite this,
misinformation receives less attention than factual content and political
moderates, who represent the bulk of users in our sample, help filter out
misinformation, reducing the amount of low factuality content in the
information ecosystem. Identifying the extent of polarization and how political
ideology can exacerbate misinformation can potentially help public health
experts and policy makers improve their messaging to promote consensus.


title:
Faraday tomography of LoTSS-DR2 data: I. Faraday moments in the
  high-latitude outer Galaxy and revealing Loop III in polarisation

abstract:
  Observations of synchrotron emission at low radio frequencies reveal a
labyrinth of polarised Galactic structures. However, the explanation for the
wealth of structures remains uncertain due to the complex interactions between
the interstellar medium and the magnetic field. A multi-tracer approach to the
analysis of large sky areas is needed. This paper aims to use polarimetric
images from the LOFAR Two metre Sky Survey (LoTSS) to produce the biggest
mosaic of polarised emission in the northern sky at low radio frequencies (150
MHz) to date. The large area this mosaic covers allows for detailed
morphological and statistical studies of polarised structures in the
high-latitude outer Galaxy, including the well-known Loop III region. We
produced a 3100 square degree Faraday tomographic cube using a rotation measure
synthesis tool. We calculated the statistical moments of Faraday spectra and
compared them with data sets at higher frequencies (1.4 GHz) and with a map of
a rotation measure derived from extragalactic sources. The mosaic is dominated
by polarised emission connected to Loop III. Additionally, the mosaic reveals
an abundance of other morphological structures, mainly {narrow and extended}
depolarisation canals, which are found to be ubiquitous. We find a correlation
between the map of an extragalactic rotation measure and the LoTSS first
Faraday moment image. The ratio of the two deviates from a simple model of a
Burn slab (Burn 1966) along the line of sight, which highlights the high level
of complexity in the magnetoionic medium that can be studied at these
frequencies.


title: Resonances for quasi-one-dimensional discrete Schr\"odinger operators

abstract:
  Consider a multichannel Laplace type operator $H_0$ on $\ell^2 ({\mathbb Z})
\otimes {\mathfrak G}$, where ${\mathfrak G}$ is an auxiliary separable Hilbert
space. For suitable compact perturbations $V$, we study the distribution of
resonances of the operator $H_0 +\omega V$, for small values of $\vert \omega
\vert$, near the thresholds of the spectrum of $H_0$. We distinguish two cases.
If ${\mathfrak G}$ is of finite dimension, resonances do not accumulate at the
thresholds. We give a geometrical description of their distribution and we
control exactly their number at least in the non-degenerate case. If
${\mathfrak G}$ is of infinite dimension, an accumulation phenomenon occurs at
some thresholds. We describe it by means of an asymptotical analysis of the
counting function of resonances.


title:
Multi-orbital tight-binding Hamiltonian and strength of spin-orbit
  interaction in strained Mg2X (X = Si, Ge, Sn, Pb)

abstract:
  We have developed multi-orbital tight-binding (MOTB) Hamiltonian models to
describe the electronic characteristics of intermetallic compounds Mg2Si,
Mg2Ge, Mg2Sn, and Mg2Pb subject to strain. We have incorporated spin-orbital
mediated interactions and calibrated the MOTB models to the band structures of
density functional theory (DFT) by a massively parallelized multi-dimensional
Monte-Carlo search algorithm. The results show that a five-band tight-binding
(TB) model reproduces the key aspects of the band structures in the entire
Brillouin zone. The five-band TB model reveals that the compressive strain
localizes the contribution of the 3s orbital of Mg to the conduction bands and
the outer shell p orbitals of X to the valence bands. The tensile strain, in
contrast, has a reversed effect and weakens the contribution of the 3s orbital
of Mg and the outer shell p orbitals of X to the conduction bands and valence
bands, respectively. We have found that the $\pi$ bonding in the Mg2X compounds
is negligible compared to the $\sigma$ bondings, follow the hierarchy
$|\sigma_{sp}|>|\sigma_{pp}|>|\sigma_{ss}|$, and the largest variation against
strain belongs to $\sigma_{pp}$. Moreover, the five-band TB model allowed for
estimating the strength of SOC in Mg2X and obtaining its functionality with
respect to the atomic number of X and strain. Additionally, the calculations
find significant band gap tuning and band splitting due to strain. It is shown
that a compressive strain of -10% can open a band gap at the $\Gamma$ point in
metallic MgPb whereas a tensile strain of +10% closes the semiconducting band
gap of Mg_2Si. Also, +5% of tensile strain can remove the three-fold degeneracy
of valence bands at the $\Gamma$ point in semiconducting Mg2Ge. Our results and
model approach can be useful in designing devices made of Mg2X more accurately.

categories: cond-mat.mtrl-sci cond-mat.mes-hall physics.app-ph physics.comp-ph quant-ph


title: Manin matrices of type C: multi-parametric deformation

abstract:
  We constructed a multi-parametric deformation of the Brauer algebra
representation related with the symplectic Lie algebras. The notion of Manin
matrix of type C was generalised to the case of the multi-parametric
deformation by using this representation and corresponding quadratic algebras.
We derived pairing operators for these quadratic algebras and minors for the
considered Manin matrices. The rank of pairing operators and dimensions of
components of quadratic algebras were calculated.


title:
The Kiloparsec-scale Neutral Atomic Carbon Outflow in the Nearby Type-2
  Seyfert Galaxy NGC 1068: Evidence for Negative AGN Feedback

abstract:
  Active galactic nucleus (AGN) feedback is postulated as a key mechanism for
regulating star formation within galaxies. Studying the physical properties of
the outflowing gas from AGN is thus crucial for understanding the co-evolution
of galaxies and supermassive black holes. Here we report 55 pc resolution ALMA
neutral atomic carbon [CI] $^3P_1\text{-}^3P_0$ observations toward the central
1 kpc of the nearby type-2 Seyfert galaxy NGC 1068, supplemented by 55 pc
resolution CO($J=1\text{-}0$) observations. We find that [CI] emission within
the central kpc is strongly enhanced by a factor of $>$5 compared to the
typical [CI]/CO intensity ratio of $\sim$0.2 for nearby starburst galaxies (in
units of brightness temperature). The most [CI]-enhanced gas (ratio $>$ 1)
exhibits a kpc-scale elongated structure centered at the AGN that matches the
known biconical ionized gas outflow entraining molecular gas in the disk. A
truncated, decelerating bicone model explains well the kinematics of the
elongated structure, indicating that the [CI] enhancement is predominantly
driven by the interaction between the ISM in the disk and the highly inclined
ionized gas outflow (which is likely driven by the radio jet). Our results
strongly favor the "CO dissociation scenario" rather than the "in-situ C
formation" one which prefers a perfect bicone geometry. We suggest that the
high [CI]/CO intensity ratio gas in NGC 1068 directly traces ISM in the disk
that is currently dissociated and entrained by the jet and the outflow, i.e.,
the "negative" effect of the AGN feedback.


title:
Testing galaxy feedback models with the first resolved profiles of the
  circumgalactic medium

abstract:
  The hot ($>10^6$ K) phase of the circumgalactic medium (CGM) contains a large
fraction of baryons in galaxies. It also retains signatures of the processes
that shaped the galaxies, such as feedback from active galactic nuclei (AGNs)
and supernovae, and offers a uniquely powerful way to constrain theoretical
models of feedback. It is, however, notoriously difficult to detect. By
stacking 2643 optically selected galaxies in the eROSITA Final Equatorial Depth
Survey (eFEDS), we present spatially resolved properties of the extended CGM in
both star-forming and quiescent galaxies spanning an order of magnitude in
stellar mass. We mask out resolved point sources and galaxy groups/clusters and
model the contribution from X-ray binaries and the hot ISM, producing accurate
radial profiles. We compare the profiles to mock X-ray observations of galaxy
stacks in the IllustrisTNG100 (TNG) and EAGLE cosmological simulations. We
detect extended emission from both the high-mass
($10.7<\log(M_*/M_\odot)<11.2$) and low-mass ($10.2<\log(M_*/M_\odot)<10.7$)
galaxy stacks. Galaxies have somewhat more luminous CGM between $10-100$~kpc if
they are more massive or star-forming. However, the luminosity increases slower
with stellar mass than predicted in simulations. Simulated quenched galaxies
are far dimmer than observed, suggesting that they rely too heavily on CGM
ejection for quenching. Star-forming galaxies are observed to have flatter and
more extended profiles than in simulations, suggesting under-efficient stellar
feedback models. Our results highlight the need to modify future prescriptions
of galaxy feedback models.


title: The Candidate Progenitor Companion Star of the Type Ib/c SN 2013ge

abstract:
  This Letter presents the detection of a source at the position of the Type
Ib/c supernova (SN) 2013ge more than four years after the radioactive component
is expected to have faded. This source could mark the first post-SN direct
detection of a surviving companion to a stripped-envelope Type Ib/c explosion.
We test this hypothesis and find the shape of the source's spectral energy
distribution is most consistent with that of a B5 I supergiant. While binary
models tend to predict OB-type stars for stripped-envelope companions, the
location of the source on a color-magnitude diagram (CMD) places it redward of
its more likely position on the main sequence (MS). The source may be
temporarily out of thermal equilibrium, or a cool and inflated non-MS
companion, which is similar to the suggested companion of Type Ib SN 2019yvr
that was constrained from pre-SN imaging. We also consider other possible
physical scenarios for the source, including a fading SN, circumstellar shock
interaction, line of site coincidence, and an unresolved host star cluster, all
of which will require future observations to more definitively rule out.
Ultimately, the fraction of surviving companions ("binary fraction") will
provide necessary constraints on binary evolution models and the underlying
physics.


title:
WISDOM Project -- X. The morphology of the molecular ISM in galaxy
  centres and its dependence on galaxy structure

abstract:
  We use high-resolution maps of the molecular interstellar medium (ISM) in the
centres of eighty-six nearby galaxies from the millimetre-Wave Interferometric
Survey of Dark Object Masses (WISDOM) and Physics at High Angular Resolution in
Nearby GalaxieS (PHANGS) surveys to investigate the physical mechanisms setting
the morphology of the ISM at molecular cloud scales. We show that early-type
galaxies tend to have smooth, regular molecular gas morphologies, while the ISM
in spiral galaxy bulges is much more asymmetric and clumpy when observed at the
same spatial scales. We quantify these differences using non-parametric
morphology measures (Asymmetry, Smoothness and Gini), and compare these
measurements with those extracted from idealised galaxy simulations. We show
that the morphology of the molecular ISM changes systematically as a function
of various large-scale galaxy parameters, including galaxy morphological type,
stellar mass, stellar velocity dispersion, effective stellar mass surface
density, molecular gas surface density, star formation efficiency and the
presence of a bar. We perform a statistical analysis to determine which of
these correlated parameters best predicts the morphology of the ISM. We find
the effective stellar mass surface (or volume) density to be the strongest
predictor of the morphology of the molecular gas, while star formation and bars
maybe be important secondary drivers. We find that gas self-gravity is not the
dominant process shaping the morphology of the molecular gas in galaxy centres.
Instead effects caused by the depth of the potential well such as shear,
suppression of stellar spiral density waves and/or inflow affect the ability of
the gas to fragment.


title:
HR 6819 is a binary system with no black hole -- revisiting the source
  with infrared interferometry and optical integral field spectroscopy

abstract:
  Two scenarios have been proposed to match the existing observational
constraints of the object HR 6819. The system could consist of a close inner
B-type giant plus a black hole (BH) binary with an additional Be companion in a
wide orbit. Alternatively, it could be a binary composed of a stripped B star
and a Be star in a close orbit. Either scenario makes HR 6819 a cornerstone
object as the stellar BH closest to Earth, or as an example of an important
transitional, non-equilibrium phase for Be stars with solid evidence for its
nature. We aimed to distinguish between the two scenarios for HR 6819. Both
models predict two luminous stars but with very different angular separations
and orbital motions. Therefore, the presence of bright sources in the 1-100
milliarcsec (mas) regime is a key diagnostic for determining the nature of the
HR 6819 system. We obtained new high-angular resolution data with VLT/MUSE and
VLTI/GRAVITY of HR 6819. The MUSE data are sensitive to bright companions at
large scales, whilst the interferometric GRAVITY data are sensitive down to
separations on mas scales and large magnitude differences. The MUSE
observations reveal no bright companion at large separations and the GRAVITY
observations indicate the presence of a stellar companion at an angular
separation of ~1.2 mas that moves on the plane of the sky over a timescale
compatible with the known spectroscopic 40-day period. We conclude that HR 6819
is a binary system and that no BH is present in the system. The unique nature
of HR 6819, and its proximity to Earth make it an ideal system for
quantitatively characterising the immediate outcome of binary interaction and
probing how Be stars form.


title:
Neural Galerkin Scheme with Active Learning for High-Dimensional
  Evolution Equations

abstract:
  Deep neural networks have been shown to provide accurate function
approximations in high dimensions. However, fitting network parameters requires
training data that may not be available beforehand, which is particularly
challenging in science and engineering applications where often it is even
unclear how to collect new informative training data in the first place. This
work proposes Neural Galerkin schemes based on deep learning that generate
training data samples with active learning for numerically solving
high-dimensional partial differential equations. Neural Galerkin schemes train
networks by minimizing the residual sequentially over time, which enables
adaptively collecting new training data in a self-informed manner that is
guided by the dynamics described by the partial differential equations, which
is in stark contrast to many other machine learning methods that aim to fit
network parameters globally in time without taking into account training data
acquisition. Our finding is that the active form of gathering training data of
the proposed Neural Galerkin schemes is key for numerically realizing the
expressive power of networks in high dimensions. Numerical experiments
demonstrate that Neural Galerkin schemes have the potential to enable
simulating phenomena and processes with many variables for which traditional
and other deep-learning-based solvers fail, especially when features of the
solutions evolve locally such as in high-dimensional wave propagation problems
and interacting particle systems described by Fokker-Planck and kinetic
equations.


title:
Role of disorder in the electronic and magnetic properties of
  Ag$_3$LiIr$_2$O$_6$

abstract:
  The nature of magnetism in the intercalated honeycomb iridate
Ag$_3$LiIr$_2$O$_6$ has been a subject of recent intensive debate, where the
absence or presence of antiferromagnetic order has been reported to be related
to possible structural disorder effects and, an enhanced Ir-O hybridization and
itinerancy with respect to the parent Li$_2$IrO$_3$ has been suggested as the
origin of distinct x-ray spectroscopy features. In the present work we
investigate the microscopic nature of the electronic and magnetic properties of
Ag$_3$LiIr$_2$O$_6$ via a combination of density functional theory combined
with exact diagonalization of ab initio-derived models for various experimental
and theoretical structures. We evaluate two possible scenarios, the itinerant
quasimolecular framework (QMO) on the one hand, and the localized relativistic
$j_{\rm eff} = 1/2$ and $j_{\rm eff} = 3/2$ picture on the other hand, and find
that the latter description is still viable for this system. We further
calculate resonant inelastic x-ray scattering spectra and show that agreement
with experimental observations can be obtained if the presence of Ag vacancies
leading to changes in Ir filling and structural disorder is assumed. Finally,
we show that the experimentally observed antiferromagnetic spiral magnetic
order is reproduced by our ab-initio derived magnetic models.


title:
Simplified Stability Assessment of Power Systems with Variable-Delay
  Wide-Area Damping Control

abstract:
  Power electronic devices such as HVDC and FACTS can be used to improve the
damping of poorly damped inter-area modes in large power systems. This involves
the use of wide-area feedback signals, which are transmitted via communication
networks. The performance of the closed-loop system is strongly influenced by
the delay associated with wide-area signals. The random nature of this delay
introduces a switched linear system model. The stability assessment of such a
system requires linear matrix inequality based approaches. This makes the
stability analysis more complicated as the system size increases. To address
this challenge, this paper proposes a delay-processing strategy that simplifies
the modelling and analysis in discrete-domain. In contrast to the existing
stability assessment techniques, the proposed approach is advantageous because
the stability, as well as damping performance, can be accurately predicted by a
simplified analysis. The proposed methodology is verified with a case study on
the 2-area 4-machine power system with a series compensated tie-line. The
results are found to be in accordance with the predictions of the proposed
simplified analysis.


title:
Faking feature importance: A cautionary tale on the use of
  differentially-private synthetic data

abstract:
  Synthetic datasets are often presented as a silver-bullet solution to the
problem of privacy-preserving data publishing. However, for many applications,
synthetic data has been shown to have limited utility when used to train
predictive models. One promising potential application of these data is in the
exploratory phase of the machine learning workflow, which involves
understanding, engineering and selecting features. This phase often involves
considerable time, and depends on the availability of data. There would be
substantial value in synthetic data that permitted these steps to be carried
out while, for example, data access was being negotiated, or with fewer
information governance restrictions. This paper presents an empirical analysis
of the agreement between the feature importance obtained from raw and from
synthetic data, on a range of artificially generated and real-world datasets
(where feature importance represents how useful each feature is when predicting
a the outcome). We employ two differentially-private methods to produce
synthetic data, and apply various utility measures to quantify the agreement in
feature importance as this varies with the level of privacy. Our results
indicate that synthetic data can sometimes preserve several representations of
the ranking of feature importance in simple settings but their performance is
not consistent and depends upon a number of factors. Particular caution should
be exercised in more nuanced real-world settings, where synthetic data can lead
to differences in ranked feature importance that could alter key modelling
decisions. This work has important implications for developing synthetic
versions of highly sensitive data sets in fields such as finance and
healthcare.


title:
Birth cluster simulations of planetary systems with multiple
  super-Earths: initial conditions for white dwarf pollution drivers

abstract:
  Previous investigations have revealed that eccentric super-Earths represent a
class of planets which are particularly effective at transporting minor bodies
towards white dwarfs and subsequently polluting their atmospheres with
observable chemical signatures. However, the lack of discoveries of these
planets beyond a few astronomical units from their host stars prompts a better
understanding of their orbital architectures from their nascent birth cluster.
Here, we perform stellar cluster simulations of 3-planet and 7-planet systems
containing super-Earths on initially circular, coplanar orbits. We adopt the
typical stellar masses of main-sequence progenitors of white dwarfs
($1.5\,\mathrm{M}_{\odot}$-$2.5\,\mathrm{M}_{\odot}$) as host stars and include
8,000 main-sequence stars following a Kroupa initial mass function in our
clusters. Our results reveal that about 30 per cent of the simulated planets
generate eccentricities of at least 0.1 by the time of cluster dissolution,
which would aid white dwarf pollution. We provide our output parameters to the
community for potential use as initial conditions for subsequent evolution
simulations.


title: The Dark Matter Halo of M54

abstract:
  M54 is a prototype of a globular cluster embedded in a dark matter halo. Gaia
EDR3 photometry and proper motions separate the old, metal-poor stars from the
more metal rich and younger dwarf galaxy stars. The metal poor stars dominate
the inner 50 pc, with a velocity dispersion profile that declines to a minimum
around 30 pc then rises back to nearly the central velocity dispersion, as
expected for a globular cluster at the center of a dark matter halo. The Jeans
analysis of the three separate stellar populations give consistent masses that
rise approximately linearly with radius to 1 kpc, implying a small core or
cuspy halo. These data are compatible with an infalling CDM dark matter halo
reduced to 3x10^8 M_sun at the 50 kpc apocenter 2.3 Gyr ago, with a central
globular cluster surrounded by the remnant of a dwarf galaxy. Tides gradually
remove material beyond 1 kpc but have little effect on the stars and dark
matter within 300 pc of the center. M54 appears to be a transitional system
between globular clusters with and without local dark halos, whose evolution
within the galaxy depends sensitively on the time of accretion and orbital
pericenter.


title:
Estimating the coronal supra-arcade downflows radio emission: from
  centimetre through submillimetre wavelengths

abstract:
  Supra-arcade downflows (SADs) are infrequent, wiggly opaque structures
observed to descend through the solar corona, mostly in EUV and soft X-ray
frequencies. From their physical characteristics, SADs have been interpreted as
voided (subdense) bubbles and are related to magnetic reconnection processes
during long-term erupting flares. In this work we use numerical MHD simulations
to compute flux density maps, which are convolved with telescope beams to
synthesise images with the aim to assess the expected SADs emission at radio
wavelengths and propose observing strategies, including the instruments that
can be used. We assume that the emission is thermal bremsstrahlung from a fully
ionised plasma without any appreciable gyroresonance contribution since
magnetic fields are of the order of ~10 G. We find that SADs emission should be
optically thin in the frequency [10-1000] GHz range, and the spatially
integrated flux should be larger than 1 Jy. We conclude, therefore, that
observing SADs in radio frequencies between [0.5-1000] GHz is feasible with
present instrumentation. Moreover, since the emission is for the most part
optically thin, the flux density is proportional to temperature, density and
line-of-sight depth, and when combined with EUV and soft X-ray images, may
allow a better density and temperature determination of SADs.


title: Review on contraction analysis and computation of contraction metrics

abstract:
  Contraction analysis considers the distance between two adjacent
trajectories. If this distance is contracting, then trajectories have the same
long-term behavior. The main advantage of this analysis is that it is
independent of the solutions under consideration. Using an appropriate metric,
with respect to which the distance is contracting, one can show convergence to
a unique equilibrium or, if attraction only occurs in certain directions, to a
periodic orbit. Contraction analysis was originally considered for ordinary
differential equations, but has been extended to discrete-time systems, control
systems, delay equations and many other types of systems. Moreover, similar
techniques can be applied for the estimation of the dimension of attractors and
for the estimation of different notions of entropy (including topological
entropy). This review attempts to link the references in both the mathematical
and the engineering literature and, furthermore, point out the recent
developments and algorithms in the computation of contraction metrics.


title: Conditional Reconstruction for Open-set Semantic Segmentation

abstract:
  Open set segmentation is a relatively new and unexploredtask, with just a
handful of methods proposed to model suchtasks.We propose a novel method called
CoReSeg thattackles the issue using class conditional reconstruction ofthe
input images according to their pixelwise mask. Ourmethod conditions each input
pixel to all known classes,expecting higher errors for pixels of unknown
classes. Itwas observed that the proposed method produces better se-mantic
consistency in its predictions, resulting in cleanersegmentation maps that
better fit object boundaries. CoRe-Seg outperforms state-of-the-art methods on
the Vaihin-gen and Potsdam ISPRS datasets, while also being com-petitive on the
Houston 2018 IEEE GRSS Data Fusiondataset. Official implementation for CoReSeg
is availableat:https://github.com/iannunes/CoReSeg.


title: ePA*SE: Edge-based Parallel A* for Slow Evaluations

abstract:
  Parallel search algorithms harness the multithreading capability of modern
processors to achieve faster planning. One such algorithm is PA*SE (Parallel A*
for Slow Expansions), which parallelizes state expansions to achieve faster
planning in domains where state expansions are slow. In this work, we propose
ePA*SE (Edge-based Parallel A* for Slow Evaluations) that improves on PA*SE by
parallelizing edge evaluations instead of state expansions. This makes ePA*SE
more efficient in domains where edge evaluations are expensive and need varying
amounts of computational effort, which is often the case in robotics. On the
theoretical front, we show that ePA*SE provides rigorous optimality guarantees.
In addition, ePA*SE can be trivially extended to handle an inflation weight on
the heuristic resulting in a bounded suboptimal algorithm w-ePA*SE (Weighted
ePA*SE) that trades off optimality for faster planning. On the experimental
front, we validate the proposed algorithm in two different planning domains: 1)
motion planning for 3D humanoid navigation and 2) task and motion planning for
a dual-arm robotic assembly task. We show that ePA*SE can be significantly more
efficient than PA*SE and other alternatives.


title: Experiments in Adaptive Replanning for Fast Autonomous Flight in Forests

abstract:
  Fast, autonomous flight in unstructured, cluttered environments such as
forests is challenging because it requires the robot to compute new plans in
realtime on a computationally-constrained platform. In this paper, we enable
this capability with a search-based planning framework that adapts sampling
density in realtime to find dynamically-feasible plans while remaining
computationally tractable. A paramount challenge in search-based planning is
that dense obstacles both necessitate large graphs (to guarantee completeness)
and reduce the efficiency of graph search (as heuristics become less accurate).
To address this, we develop a planning framework with two parts: one that
maximizes planner completeness for a given graph size, and a second that
dynamically maximizes graph size subject to computational constraints. This
framework is enabled by motion planning graphs that are defined by a single
parameter, dispersion, which quantifies the maximum trajectory cost to reach an
arbitrary state from the graph. We show through real and simulated experiments
how the dispersion can be adapted to different environments in realtime,
allowing operation in environments with varying density. The simulated
experiment demonstrates improved performance over a baseline search-based
planning algorithm. We also demonstrate flight speeds of up to 2.5m/s in
real-world cluttered pine forests.


title: Micromechanics-based phase field fracture modelling of CNT composites

abstract:
  We present a novel micromechanics-based phase field approach to model crack
initiation and propagation in carbon nanotube (CNT) based composites. The
constitutive mechanical and fracture properties of the nanocomposites are first
estimated by a mean-field homogenisation approach. Inhomogeneous dispersion of
CNTs is accounted for by means of equivalent inclusions representing
agglomerated CNTs. Detailed parametric analyses are presented to assess the
effect of the main micromechanical properties upon the fracture behaviour of
CNT-based composites. The second step of the proposed approach incorporates the
previously estimated constitutive properties into a phase field fracture model
to simulate crack initiation and growth in CNT-based composites. The modelling
capabilities of the framework presented is demonstrated through three
paradigmatic case studies involving mode I and mixed mode fracture conditions.


title:
A persistent ultraviolet outflow from an accreting neutron star binary
  transient

abstract:
  All disc-accreting astrophysical objects produce powerful outflows. In
binaries containing neutron stars (NS) or black holes, accretion often takes
place during violent outbursts. The main disc wind signatures during these
eruptions are blue-shifted X-ray absorption lines, which are preferentially
seen in disc-dominated "soft states". By contrast,optical wind-formed lines
have recently been detected in "hard states", when a hot corona dominates the
luminosity. The relationship between these signatures is unknown, and no
erupting system has revealed wind-formed lines between the X-ray and optical
bands yet, despite the many strong resonance transitions in this ultraviolet
(UV) region. Here, we show that the transient NS binary Swift J1858.6-0814
exhibits wind-formed, blue-shifted absorption associated with C IV, N V and He
II in time-resolved UV spectroscopy during a luminous hard state. This
represents the first evidence for a warm, moderately ionized outflow component
in this state. Simultaneously observed optical lines also display transient
blue-shifted absorption. Decomposing the UV data into constant and variable
components, the blue-shifted absorption is associated with the former. This
implies that the outflow is not connect to the luminous flares in the data. The
joint presence of UV and optical wind features reveals a multi-phase and/or
stratified outflow from the outer disc. This type of persistent mass loss
across all accretion states has been predicted by radiation-hydrodynamic
simulations and helps to explain the shorter-than-expected outbursts duration.


title: Privacy-Aware Crowd Labelling for Machine Learning Tasks

abstract:
  The extensive use of online social media has highlighted the importance of
privacy in the digital space. As more scientists analyse the data created in
these platforms, privacy concerns have extended to data usage within the
academia. Although text analysis is a well documented topic in academic
literature with a multitude of applications, ensuring privacy of user-generated
content has been overlooked. Most sentiment analysis methods require emotion
labels, which can be obtained through crowdsourcing, where non-expert
individuals contribute to scientific tasks. The text itself has to be exposed
to third parties in order to be labelled. In an effort to reduce the exposure
of online users' information, we propose a privacy preserving text labelling
method for varying applications, based in crowdsourcing. We transform text with
different levels of privacy, and analyse the effectiveness of the
transformation with regards to label correlation and consistency. Our results
suggest that privacy can be implemented in labelling, retaining the
annotational diversity and subjectivity of traditional labelling.


title:
Personal Data Visualisation on Mobile Devices: A Systematic Literature
  Review

abstract:
  Personal data cover multiple aspects of our daily life and activities,
including health, finance, social, Internet, Etc. Personal data visualisations
aim to improve the user experience when exploring these large amounts of
personal data and potentially provide insights to assist individuals in their
decision making and achieving goals. People with different backgrounds, gender
and ages usually need to access their data on their mobile devices. Although
there are many personal tracking apps, the user experience when using these
apps and visualisations is not evaluated yet. There are publications on
personal data visualisation in the literature. Still, no systematic literature
review investigated the gaps in this area to assist in developing new personal
data visualisation techniques focusing on user experience. In this systematic
literature review, we considered studies published between 2010 and 2020 in
three online databases. We screened 195 studies and identified 29 papers that
met our inclusion criteria. Our key findings are various types of personal
data, and users have been addressed well in the found papers, including health,
sport, diet, Driving habits, lifelogging, productivity, Etc. The user types
range from naive users to expert and developers users based on the experiment's
target. However, mobile device capabilities and limitations regarding data
visualisation tasks have not been well addressed. There are no studies on the
best practices of personal data visualisation on mobile devices, assessment
frameworks for data visualisation, or design frameworks for personal data
visualisations


title:
From Digital Media to Empathic Reality: A Systematic Review of Empathy
  Research in Extended Reality Environments

abstract:
  Recent advances in extended reality (XR) technologies have enabled new and
increasingly realistic empathy tools and experiences. In XR, all interactions
take place in different spatial contexts, all with different features,
affordances, and constraints. We present a systematic literature survey of
recent work on empathy in XR. As a result, we contribute a research roadmap
with three future opportunities in XR-enabled empathy research across both
physical and virtual spaces.


title:
Homogeneous ice nucleation in an ab initio machine learning model of
  water

abstract:
  Molecular simulations have provided valuable insight into the microscopic
mechanisms underlying homogeneous ice nucleation. While empirical models have
been used extensively to study this phenomenon, simulations based on
first-principles calculations have so far proven prohibitively expensive. Here,
we circumvent this difficulty by using an efficient machine learning model
trained on density-functional theory (DFT) energies and forces. We compute
nucleation rates at atmospheric pressure, over a broad range of supercoolings,
using the seeding technique and systems of up to hundreds of thousands of atoms
simulated with ab initio accuracy. The key quantity provided by the seeding
technique is the size of the critical cluster (i.e., a size such that the
cluster has equal probabilities of growing or melting at the given
supersaturation) which is used together with the equations of classical
nucleation theory to compute nucleation rates. We find that nucleation rates
for our model at moderate supercoolings are in good agreement with experimental
measurements within the error of our calculation. We also study the impact of
properties such as the thermodynamic driving force, interfacial free energy,
and stacking disorder on the calculated rates.


title:
Intrinsic spin-valley locking for conducting electrons in
  metal-semiconductor-metal lateral hetero-structures of $1H$-transition-metal
  dichalcogenides

abstract:
  Lateral-hetero structures of atomic layered materials alter the electronic
properties of pristine crystals and provide a possibility to produce useful
monolayer materials. We reveal that metal-semiconductor-metal lateral-hetero
junctions of $1H$-transition-metal dichalcogenides intrinsically possess
conducting channels of electrons with spin-valley locking, e.g., gate
electrode. We theoretically investigate the electronic structure and transport
properties of the lateral-hetero junctions and show that the hetero-structure
produces conducting channels through the $K$ and $K'$ valleys in the
semiconducting transition-metal dichalcogenide and restricts the spin of the
conducting electrons in each valley due to the valley dependent charge transfer
effect. Moreover, the theoretical investigation shows that the hetero-junction
of WSe$_2$ realizes a high transmission probability for valley-spin locked
electrons even in a long semiconducting region. The hetero-junction also
provides a useful electronic transport property, a step-like I-V
characteristic.


title:
The 2021 outburst of RS Oph: a pictorial atlas of the spectroscopic
  evolution. II. From day 19 to 102 (solar conjunction)

abstract:
  We present the second part (days 19 to 102) of our high-resolution Echelle
atlas of the spectral evolution of RS Oph during the 2021 nova outburst. Some
quick conclusions that can be drawn are: (1) the spectra evolution has
progressed smoothly, suggesting that both the expansion of the ejecta through
the pre-existing RG wind and the photo-ionization from the central source did
not encountered sudden discontinuities prior to switch-off of the nuclear
burning; (2) the 2021 spectral evolution is similar to that of the 2006
eruption, with a mirror-appearance of the triple-peaked line profiles (blue
peak brighter than red in 2006, the opposite in 2021); (3) the evolution of the
triple-peaked profiles progressed similarly through different excitation and
ionization degrees, suggesting an origin in a bipolar outflow nested to an
equatorial torus; (4) the time-behavior of coronal emission lines appears quite
smooth, both in terms of radiated flux as well as evolution of the
triple-peaked profiles, with a plateau at maximum lasting up to about day 87;
(5) there seems to exist within RS Oph two distinct types of ejecta: one fast
moving and producing Gaussian-like line profiles (primarely [NII] and [OIII]),
that keep expanding at FWHM=1000 km/s with no sign of ongoing deceleration
during the two months leading up to Solar conjunction, and slower moving ejecta
giving rise to the triple-peaked line profiles (HeI, HeII, coronal lines, and
also Balmer lines at later times), for which the separation in velocity of blue
and red peaks is still shrinking at the time of Solar conjunction when it
reaches an average of 330 km/s; (6) the "symbiotic band" at 6825 Ang, due to
Raman scattering of OVI 1032 by neutral hydrogen, appears simultaneously with
the coronal lines: its very presence indicates that a sizeable part of the wind
of the red giant has remained neutral during the development of coronal lines.


title: Code Properties of the Holographic Sierpinski Triangle

abstract:
  We study the holographic quantum error correcting code properties of a
Sierpinski Triangle-shaped boundary subregion in $AdS_4/CFT_3$. Due to existing
no-go theorems in topological quantum error correction regarding fractal noise,
this gives holographic codes a specific advantage over topological codes. We
then further argue that a boundary subregion in the shape of the Sierpinski
gasket in $AdS_5/CFT_4$ does not possess these holographic quantum error
correction properties.


title: Over-Relaxation in Diffusive Integer Lattice Gas

abstract:
  One of the most striking draw-backs of standard lattice gas methods over
lattice Boltzmann methods is a much more limited range of transport parameters
that can be achieved. It is common for lattice Boltzmann methods to use
over-relaxation to achieve arbitrarily small transport parameters in the
hydrodynamic equations. Here, we show that it is possible to implement
over-relaxation for integer lattice gases. For simplicity we focus here on
lattice gases for the diffusion equation. We demonstrate that adding a flipping
operation to lattice gases results in a multi-relaxation time lattice Boltzmann
scheme with over-relaxation in the Boltzmann limit.


title: Stable and Semi-stable Sampling Approaches for Continuously Used Samples

abstract:
  Information retrieval systems are usually measured by labeling the relevance
of results corresponding to a sample of user queries. In practical search
engines, such measurement needs to be performed continuously, such as daily or
weekly. This creates a trade-off between (a) representativeness of query sample
to current query traffic of the product; (b) labeling cost: if we keep the same
query sample, results would be similar allowing us to reuse their labels; and
(c) overfitting caused by continuous usage of same query sample. In this paper
we explicitly formulate this tradeoff, propose two new variants -- Stable and
Semi-stable -- to simple and weighted random sampling and show that they
outperform existing approaches for the continuous usage settings, including
monitoring/debugging search engine or comparing ranker candidates.


title:
Nemo: Guiding and Contextualizing Weak Supervision for Interactive Data
  Programming

abstract:
  Weak Supervision (WS) techniques allow users to efficiently create large
training datasets by programmatically labeling data with heuristic sources of
supervision. While the success of WS relies heavily on the provided labeling
heuristics, the process of how these heuristics are created in practice has
remained under-explored. In this work, we formalize the development process of
labeling heuristics as an interactive procedure, built around the existing
workflow where users draw ideas from a selected set of development data for
designing the heuristic sources. With the formalism, we study two core problems
of how to strategically select the development data to guide users in
efficiently creating informative heuristics, and how to exploit the information
within the development process to contextualize and better learn from the
resultant heuristics. Building upon two novel methodologies that effectively
tackle the respective problems considered, we present Nemo, an end-to-end
interactive system that improves the overall productivity of WS learning
pipeline by an average 20% (and up to 47% in one task) compared to the
prevailing WS approach.


title: Disordered crystals reveal soft quasilocalized glassy excitations

abstract:
  Structural glasses formed by quenching a melt are known to host a population
of low-energy quasilocalized (nonphononic) excitations whose frequencies
$\omega$ follow a universal $\sim\!\omega^4$ distribution as $\omega\!\to\!0$,
independently of the glass formation history, the interparticle interaction
potential or spatial dimension. Here, we show that the universal quartic law of
nonphononic excitations also holds in disordered crystals featuring finite
long-range order, which is absent in their glassy counterparts. We thus
establish that the degree of universality of the quartic law extends beyond
structural glasses quenched from a melt. We further find that disordered
crystals, whose level of disorder can be continuously controlled, host many
more quasilocalized excitations than expected based on their degree of
mechanical disorder -- quantified by the relative fluctuations of the shear
modulus -- as compared to structural glasses featuring a similar degree of
mechanical disorder. Finally, we show that the stability bound on nonlinear
quasilocalized excitations -- previously established in structural glasses --
also holds in disordered crystals. Our results are related to glass-like
anomalies experimentally observed in disordered crystals. More broadly, they
constitute an important step towards tracing the essential ingredients
necessary for the emergence of universal nonphononic excitations in disordered
solids.

categories: cond-mat.dis-nn cond-mat.mtrl-sci cond-mat.soft cond-mat.stat-mech


title:
Descending Price Auctions with Bounded Number of Price Levels and
  Batched Prophet Inequality

abstract:
  We consider descending price auctions for selling $m$ units of a good to unit
demand i.i.d. buyers where there is an exogenous bound of $k$ on the number of
price levels the auction clock can take. The auctioneer's problem is to choose
price levels $p_1 > p_2 > \cdots > p_{k}$ for the auction clock such that
auction expected revenue is maximized. The prices levels are announced prior to
the auction. We reduce this problem to a new variant of prophet inequality,
which we call \emph{batched prophet inequality}, where a decision-maker chooses
$k$ (decreasing) thresholds and then sequentially collects rewards (up to $m$)
that are above the thresholds with ties broken uniformly at random. For the
special case of $m=1$ (i.e., selling a single item), we show that the resulting
descending auction with $k$ price levels achieves $1- 1/e^k$ of the
unrestricted (without the bound of $k$) optimal revenue. That means a
descending auction with just 4 price levels can achieve more than 98\% of the
optimal revenue. We then extend our results for $m>1$ and provide a closed-form
bound on the competitive ratio of our auction as a function of the number of
units $m$ and the number of price levels $k$.


title:
Spectrally-modified frequency-swept pulses for optically-driven quantum
  light sources

abstract:
  We present a driving scheme for solid-state quantum emitters using
frequency-swept pulses containing a spectral hole resonant with the optical
transition in the emitter. Our scheme enables high-fidelity state inversion,
exhibits robustness to variations in the laser pulse parameters and is immune
to phonon-mediated excitation-induced dephasing, benefits that derive from the
the insensitivity of the adiabaticity condition to variations in the
experimental parameters. Our resonant driving approach could be combined with
spectral filtering of the scattered pump light and photonic devices for
enhanced collection efficiency to realize simultaneous high
indistinguishability and brightness in single photon source applications.


title:
Exploring Hierarchical Graph Representation for Large-Scale Zero-Shot
  Image Classification

abstract:
  The main question we address in this paper is how to scale up visual
recognition of unseen classes, also known as zero-shot learning, to tens of
thousands of categories as in the ImageNet-21K benchmark. At this scale,
especially with many fine-grained categories included in ImageNet-21K, it is
critical to learn quality visual semantic representations that are
discriminative enough to recognize unseen classes and distinguish them from
seen ones. We propose a Hierarchical Graphical knowledge Representation
framework for the confidence-based classification method, dubbed as HGR-Net.
Our experimental results demonstrate that HGR-Net can grasp class inheritance
relations by utilizing hierarchical conceptual knowledge. Our method
significantly outperformed all existing techniques, boosting the performance 7%
compared to the runner-up approach on the ImageNet-21K benchmark. We show that
HGR-Net is learning-efficient in few-shot scenarios. We also analyzed our
method on smaller datasets like ImageNet-21K-P, 2-hops and 3-hops,
demonstrating its generalization ability. Our benchmark and code will be made
publicly available.


title:
A Survey on Offline Reinforcement Learning: Taxonomy, Review, and Open
  Problems

abstract:
  With the widespread adoption of deep learning, reinforcement learning (RL)
has experienced a dramatic increase in popularity, scaling to previously
intractable problems, such as playing complex games from pixel observations,
sustaining conversations with humans, and controlling robotic agents. However,
there is still a wide range of domains inaccessible to RL due to the high cost
and danger of interacting with the environment. Offline RL is a paradigm that
learns exclusively from static datasets of previously collected interactions,
making it feasible to extract policies from large and diverse training
datasets. Effective offline RL algorithms have a much wider range of
applications than online RL, being particularly appealing for real-world
applications such as education, healthcare, and robotics. In this work, we
propose a unifying taxonomy to classify offline RL methods. Furthermore, we
provide a comprehensive review of the latest algorithmic breakthroughs in the
field, and a review of existing benchmarks' properties and shortcomings.
Finally, we provide our perspective on open problems and propose future
research directions for this rapidly growing field.


title: Skew-Symmetric Adjacency Matrices for Clustering Directed Graphs

abstract:
  Cut-based directed graph (digraph) clustering often focuses on finding dense
within-cluster or sparse between-cluster connections, similar to cut-based
undirected graph clustering methods. In contrast, for flow-based clusterings
the edges between clusters tend to be oriented in one direction and have been
found in migration data, food webs, and trade data. In this paper we introduce
a spectral algorithm for finding flow-based clusterings. The proposed algorithm
is based on recent work which uses complex-valued Hermitian matrices to
represent digraphs. By establishing an algebraic relationship between a
complex-valued Hermitian representation and an associated real-valued,
skew-symmetric matrix the proposed algorithm produces clusterings while
remaining completely in the real field. Our algorithm uses less memory and
asymptotically less computation while provably preserving solution quality. We
also show the algorithm can be easily implemented using standard computational
building blocks, possesses better numerical properties, and loans itself to a
natural interpretation via an objective function relaxation argument.


title:
Graph-based Multi-sensor Fusion for Consistent Localization of
  Autonomous Construction Robots

abstract:
  Enabling autonomous operation of large-scale construction machines, such as
excavators, can bring key benefits for human safety and operational
opportunities for applications in dangerous and hazardous environments. To
facilitate robot autonomy, robust and accurate state-estimation remains a core
component to enable these machines for operation in a diverse set of complex
environments. In this work, a method for multi-modal sensor fusion for robot
state-estimation and localization is presented, enabling operation of
construction robots in real-world scenarios. The proposed approach presents a
graph-based prediction-update loop that combines the benefits of filtering and
smoothing in order to provide consistent state estimates at high update rate,
while maintaining accurate global localization for large-scale earth-moving
excavators. Furthermore, the proposed approach enables a flexible integration
of asynchronous sensor measurements and provides consistent pose estimates even
during phases of sensor dropout. For this purpose, a dual-graph design for
switching between two distinct optimization problems is proposed, directly
addressing temporary failure and the subsequent return of global position
estimates. The proposed approach is implemented on-board two Menzi Muck walking
excavators and validated during real-world tests conducted in representative
operational environments.


title: Formalizing Elements of Probabilistic Mechanics

abstract:
  In this paper we create a model of particle motion on a three-dimensional
lattice using discrete random walk with small steps. We rigorously construct a
probability space of the particle trajectories. Unlike deterministic approach
in classical mechanics, here we use probabilistic properties of particle
movement to formally derive analogues of Newton's first and second laws of
motion. Similar probabilistic models can potentially be applied to justify laws
of thermodynamics in a consistent manner.


title: DDL-MVS: Depth Discontinuity Learning for MVS Networks

abstract:
  Traditional MVS methods have good accuracy but struggle with completeness,
while recently developed learning-based multi-view stereo (MVS) techniques have
improved completeness except accuracy being compromised. We propose depth
discontinuity learning for MVS methods, which further improves accuracy while
retaining the completeness of the reconstruction. Our idea is to jointly
estimate the depth and boundary maps where the boundary maps are explicitly
used for further refinement of the depth maps. We validate our idea and
demonstrate that our strategies can be easily integrated into the existing
learning-based MVS pipeline where the reconstruction depends on high-quality
depth map estimation. Extensive experiments on various datasets show that our
method improves reconstruction quality compared to baseline. Experiments also
demonstrate that the presented model and strategies have good generalization
capabilities. The source code will be available soon.


title:
Algebraic hyperbolicity of very general hypersurfaces in products of
  projective spaces

abstract:
  We study the algebraic hyperbolicity of very general hypersurfaces in
$\mathbb{P}^m \times \mathbb{P}^n$ by using three techniques that build on past
work by Ein, Voisin, Pacienza, Coskun and Riedl, and others. As a result, we
completely answer the question of whether or not a very general hypersurface of
bidegree $(a,b)$ in $\mathbb{P}^m \times \mathbb{P}^n$ is algebraically
hyperbolic, except in $\mathbb{P}^3 \times \mathbb{P}^1$ for the bidegrees
$(a,b)= (7,3), (6,3)$ and $(5,b)$ with $b\geq 3.$ As another application of
these techniques, we improve the known result that very general hypersurfaces
in $\mathbb{P}^n$ of degree at least $2n-2$ are algebraically hyperbolic when
$n\geq 6$ to $n \geq 5$, leaving $n=4$ as the only open case.


title:
The role of band matching in the proximity effect between a
  superconductor and a normal metal

abstract:
  We combine density functional theory and scanning tunneling microscopy to
study the proximity effects between a bulk Ru(0001) superconductor and an
atomically thin overlayer of Co. We have identified that the Co monolayer can
grow in two different stackings: the hcp and a reconstructed \textepsilon-like
stacking. We analyze their electronic structure from both experiments and
density functional theory. While the magnetic hcp stacking shows a weak
proximity effect in combination with Shiba states and with almost no
suppression of superconductivity of the substrate, the more complex
\textepsilon-like stacking becomes almost fully superconducting and displays an
edge state at the island rim. We identify this edge state as a trivial state
caused by a local hcp rim around the \textepsilon-core. We explain the weak
proximity effect between Ru and the magnetic hcp islands by a low transparency
of the interface, while the large chemical unit cell of the non-magnetic
\textepsilon-like stacking lifts the momentum conservation at the interface
making it transparent and causing a clear proximity effect.


title:
Detecting Chronic Kidney Disease(CKD) at the Initial Stage: A Novel
  Hybrid Feature-selection Method and Robust Data Preparation Pipeline for
  Different ML Techniques

abstract:
  Chronic Kidney Disease (CKD) has infected almost 800 million people around
the world. Around 1.7 million people die each year because of it. Detecting CKD
in the initial stage is essential for saving millions of lives. Many
researchers have applied distinct Machine Learning (ML) methods to detect CKD
at an early stage, but detailed studies are still missing. We present a
structured and thorough method for dealing with the complexities of medical
data with optimal performance. Besides, this study will assist researchers in
producing clear ideas on the medical data preparation pipeline. In this paper,
we applied KNN Imputation to impute missing values, Local Outlier Factor to
remove outliers, SMOTE to handle data imbalance, K-stratified K-fold
Cross-validation to validate the ML models, and a novel hybrid feature
selection method to remove redundant features. Applied algorithms in this study
are Support Vector Machine, Gaussian Naive Bayes, Decision Tree, Random Forest,
Logistic Regression, K-Nearest Neighbor, Gradient Boosting, Adaptive Boosting,
and Extreme Gradient Boosting. Finally, the Random Forest can detect CKD with
100% accuracy without any data leakage.


title: Neutrino mass measurements using cryogenic detectors

abstract:
  The determination of the absolute mass scale of neutrinos is one of the most
important challenges in Particle Physics. The shape of the endpoint region of
$\beta$-decay and electron capture (EC) spectra depends on the phase space
factor, which, in turn, is function of the neutrino mass eigenstates. High
energy resolution and high statistics measurements of $\beta$- and EC spectra
are therefore considered a model-independent way for the determination of the
neutrino mass scale. Since almost four decades, low temperature
microcalorimeters are used for the measurement of low energy $\beta$- and EC
spectra. The first efforts were focused on the development of large arrays for
the measurement of the $^{187}$Re $\beta$-spectrum. In the last ten years, the
attention moved to EC of $^{163}$Ho. This choice was mainly motivated by the
very good performance which could be achieved with low temperature
microcalorimeters enclosing $^{163}$Ho with respect to microcalorimeters with
absorber containing $^{187}$Re. The development of low temperature
microcalorimeters for the measurement of the finite neutrino mass is discussed
and, in particular, the reasons for moving from $^{187}$Re to $^{163}$Ho. The
possibility to reach sub-eV sensitivity on the effective electron neutrino mass
with $^{163}$Ho, thanks to the multiplexing of large microcalorimeter arrays is
demonstrated. In conclusion, an overview on other nuclides which have been
proposed as good candidates, motivated by the excellent performance of low
temperature microcalorimeters is presented.


title: Good things to do with extra Higgs doublets

abstract:
  In this contribution to the Snowmass 2021 process, we outline models with two
or three Higgs doublets that address open questions of particle physics and
cosmology. In particular, we show that with two additional Higgs doublets one
can provide a mechanism for the generation of lepton asymmetry and hence baryon
asymmetry, through CP violating Higgs decays, near weak scale temperatures. In
another model with only one extra Higgs doublet, we illustrate that Yukawa
couplings to quarks and neutrinos can lead to a viable mechanism for the
generation of Dirac neutrino masses, sourced by the QCD chiral condensate of
strange quarks. We adapt Spontaneous Flavor Violation -- a framework for
coupling light fermions to new Higgs doublets while avoiding tree level
flavor-changing neutral currents -- in constructing these models. In both
cases, flavor data provide interesting constraints on the parameter space.
Either scenario includes $\mathcal{O}{(1)}$ couplings of light quarks to the
Higgs doublets which allow a future 100 TeV $pp$ collider to have reach for the
new scalars up to $\mathcal{O}{(10~{\rm TeV})}$ masses, through resonant single
production. In the neutrino mass model, collider data can shed light on the
mass hierarchy of neutrinos. This article is based on work presented in Refs.
[1,2].


title: The Asteroid-Comet Continuum

abstract:
  The practical distinctions between asteroids and comets, viewed as products
of accretion on either side of the snow line, are less clear-cut than
previously understood. In this chapter, we discuss the numerous solar system
populations which have physical and dynamical properties that conflict with any
simple diagnosis of their nature and origin. Studies of these so-called
"continuum" or "transition objects", which include many of the most intriguing
bodies in the solar system, have implications for a broad range of scientific
topics from the demise of comets and the activation of asteroids to the
production of interplanetary debris and the origin of the terrestrial planet
volatiles. We present an overview of the current state of knowledge concerning
the asteroid-comet continuum and discuss the numerous physical processes behind
the activity shown by small bodies in the solar system.


title:
Structural Design and Impact Analysis of a 1.5U CubeSat on the Lunar
  Surface

abstract:
  Ahead of the United States' crewed return to the moon in 2024, Intuitive
Machines, under a NASA Commercial Lunar Payload Services contract, will land
their Nova-C lunar lander in October 2021. At 30 meters altitude during the
terminal descent, EagleCam will be deployed, and will capture and transmit the
first-ever third-person images of a spacecraft making an extraterrestrial
landing. This paper will focus on the structural design, modeling, and impact
analysis of a 1.5U CubeSat payload to withstand a ballistic, soft-touch landing
on the lunar surface.


title: Optomechanical simulation of a parametric oscillator

abstract:
  We study an optomechhanical device supporting at least three optical modes in
the infrared telecommunication band and three mechanical vibration modes. We
model the coherent driving of each optical mode, independently of each other,
to obtain an effective Hamiltonian showing the different types of parametric
processes allowed in the device. We propose a bichromatic driving scheme, in
the lossy optical cavity regime, under a mean field approximation, that
provides the quantum simulation of a parametric oscillator with optical control
of its parameters.


title: Adaptive Gradient Methods with Local Guarantees

abstract:
  Adaptive gradient methods are the method of choice for optimization in
machine learning and used to train the largest deep models. In this paper we
study the problem of learning a local preconditioner, that can change as the
data is changing along the optimization trajectory. We propose an adaptive
gradient method that has provable adaptive regret guarantees vs. the best local
preconditioner. To derive this guarantee, we prove a new adaptive regret bound
in online learning that improves upon previous adaptive online learning
methods. We demonstrate the robustness of our method in automatically choosing
the optimal learning rate schedule for popular benchmarking tasks in vision and
language domains. Without the need to manually tune a learning rate schedule,
our method can, in a single run, achieve comparable and stable task accuracy as
a fine-tuned optimizer.


title: Optical precursors in waveguide quantum electrodynamics

abstract:
  When a broadband signal propagates through a dispersive medium, some
frequency components move faster than the center of the pulse. This leads to
the appearance of precursors, rapidly oscillating waves that emerge from the
medium earlier than the main signal and seem to propagate superluminally. Here,
we investigate the microscopic origin of precursors in a minimal setup: an
array of qubits coupled to a waveguide. The linear transmission function only
converges to that of a continuous medium for large qubit numbers. Nevertheless,
oscillations in the transmitted field persist even for only two qubits, which
is the minimum number required for the emergence of precursors. Precursors are
best observed under conditions of electromagnetically-induced transparency, as
the center of the pulse is significantly delayed. Under these conditions, just
a single qutrit is enough to generate a precursor. Our results pave the way
towards dispersion engineering of light with just a few qubits, and can be
realized with superconducting qubits coupled to transmission lines or atoms
coupled to optical waveguides.


title: Fixed point-free pseudo-Anosovs and the cinquefoil

abstract:
  We show that the pseudo-Anosov representative of any genus-two, hyperbolic,
fibered knot in $S^3$ (with nonzero fractional Dehn twist coefficient) has a
fixed point. Combined with previous work of Baldwin--Hu--Sivek, this proves
that the cinquefoil knot $T(2,5)$ is the only genus-two L-space knot. Our
results have applications to the Floer homology of cyclic branched covers over
knots in $S^3$, to $\mathit{SU}(2)$-abelian Dehn surgeries, and to Khovanov and
annular Khovanov homology. Along the way to proving our fixed point result, we
describe for each stratum $\mathcal{Q}$ on a punctured disk (satisfying a very
mild condition), a small list of train tracks carrying all pseudo-Anosovs in
$\mathcal{Q}$. As a consequence, we find a canonical track $\tau$ carrying all
pseudo-Anosovs in a particular stratum $\mathcal{Q}_0$ on the genus-two surface
with one boundary component, and describe every fixed point-free pseudo-Anosov
in $\mathcal{Q}_0$. The main technical tools in our proofs are a restrictive
variant of splitting for pseudo-Anosov braids, and a careful analysis of train
track maps on the canonical track $\tau$.


title: Modeling of an On-Orbit Maintenance Robotic Arm Test-Bed

abstract:
  This paper focuses on the development of a ground-based test-bed to analyze
the complexities of contact dynamics between multibody systems in space. The
test-bed consists of an air-bearing platform equipped with a 7
degrees-of-freedom (one degree per revolute joint) robotic arm which acts as
the servicing satellite. The dynamics of the manipulator on the platform is
modeled as an aid for the analysis and design of stabilizing control algorithms
suited for autonomous on-orbit servicing missions.
  The dynamics are represented analytically using a recursive Newton-Euler
multibody method with D-H parameters derived from the physical properties of
the arm and platform. In addition, Product of Exponential (PoE) method is also
employed to serve as a comparison with the D-H parameters approach. Finally, an
independent numerical simulation created with the SimScape modeling environment
is also presented as a means of verifying the accuracy of the recursive model
and the PoE approach. The results from both models and SimScape are then
validated through comparison with internal measurement data taken from the
robotic arm itself.


title:
Self-Supervised Online Learning for Safety-Critical Control using Stereo
  Vision

abstract:
  With the increasing prevalence of complex vision-based sensing methods for
use in obstacle identification and state estimation, characterizing
environment-dependent measurement errors has become a difficult and essential
part of modern robotics. This paper presents a self-supervised learning
approach to safety-critical control. In particular, the uncertainty associated
with stereo vision is estimated, and adapted online to new visual environments,
wherein this estimate is leveraged in a safety-critical controller in a robust
fashion. To this end, we propose an algorithm that exploits the structure of
stereo-vision to learn an uncertainty estimate without the need for
ground-truth data. We then robustify existing Control Barrier Function-based
controllers to provide safety in the presence of this uncertainty estimate. We
demonstrate the efficacy of our method on a quadrupedal robot in a variety of
environments. When not using our method safety is violated. With offline
training alone we observe the robot is safe, but overly-conservative. With our
online method the quadruped remains safe and conservatism is reduced.


title:
Superconducting Phase of $\mathrm{TiO_x}$ Thin Films Grown by Molecular
  Beam Epitaxy

abstract:
  We investigate the structural and transport properties of $\mathrm{TiO_x}$
thin films grown by molecular beam epitaxy. The transport and structural
properties are found to be dependent on the growth conditions and the film
thickness. Transport properties ranging from metallicity to superconductivity
and insulating states are stabilized by effectively tuning the growth oxygen
pressure, the film thickness, and the Ti rate. A semiconducting-superconducting
transition is observed at 4.5 K for 85 nm thick $\mathrm{TiO_x}$ films grown on
(0001)-$\mathrm{Al_2 O_3}$ substrates at 850$^{\circ}$ C. Synchrotron
diffraction measurements confirm the co-existence of multiple TiO$_x$ phases
including the trigonal $\mathrm{Ti_2 O_3}$ phase, $\mathrm{\gamma-Ti_3 O_5}$
and cubic $\mathrm{TiO_x}$ phase for the superconducting, metallic and
insulating films. Phase-separation is directly imaged using high-resolution
synchrotron X-ray diffraction-based mapping. Unraveling the complex
relationship between the electronic and structural properties of transition
metal oxide thin films is critical for understanding and enhancing their
functional properties.


title: The MKID Science Data Pipeline

abstract:
  We present The MKID Pipeline, a general use science data pipeline for the
reduction and analysis of ultraviolet, optical and infrared (UVOIR) Microwave
Kinetic Inductance Detector (MKID) data sets. This paper provides an
introduction to the nature of MKID data sets, an overview of the calibration
steps included in the pipeline, and an introduction to the implementation of
the software.


title:
The Mobile Production Vehicle Routing Problem: Using 3D Printing in Last
  Mile Distribution

abstract:
  We study a new variant of the vehicle routing problem, called the Mobile
Production Vehicle Routing Problem (MoP-VRP). In this problem, vehicles are
equipped with 3D printers, and production takes place on the way to the
customer. The objective is to minimize the weighted cost incurred by travel and
delay of service. We formulate a Mixed Integer Programming (MIP) model and
develop an Adaptive Large Neighbourhood Search (ALNS) heuristic for this
problem. To show the advantage of mobile production, we compare the problem
with the Central Production Vehicle Routing Problem (CP-VRP), where production
takes place in a central depot. We also propose an efficient ALNS for the
CP-VRP. We generate benchmark instances based on Vehicle Routing Problem with
Time Windows (VRPTW) benchmark instances, and realistic instances based on
real-life data provided by the Danish Company 3D Printhuset. Overall, the
proposed ALNS for both problems are efficient, and we solve instances up to 200
customers within a short computational time. We test different scenarios with
varying numbers of machines in each vehicle, as well as different production
time. The results show that these are the key factors that influence travel and
delay costs. The key advantage of mobile production is flexibility: it can
shorten the time span from the start of production to the delivery of products,
and at the same time lower delivery costs. Moreover, long-term cost estimations
show that this technology has low operation costs and thus is feasible in real
life practice.


title:
Further analysis on structure and spectral properties of symmetric
  graphs

abstract:
  Graph is an abstract representation commonly used to model networked systems
and structure. In problems across various fields, including computer vision and
pattern recognition, and neuroscience, graphs are often brought into comparison
(a process is called \textit{graph matching}) or checked for symmetry.
Friendliness property of the associated adjacency matrices, specified by their
spectral properties, is important in deriving a convex relaxation of the
(intractable) discrete graph matching problem. In this work, we study
unfriendliness properties of symmetric graphs by studying its relation to the
underlying graph structure. It is revealed that a symmetric graph has two or
more subgraphs of the same topology, and are adjacent to the same set of
vertices. We then show that if adjacency matrices of symmetric graphs have
distinct eigenvalues then there exist eigenvectors orthogonal to the vector of
all ones, making them unfriendly. Relation of graph symmetry to
uncontrollability of multi-agent systems under agreement dynamics with one
controlled node is revisited. Examples of both synthetic and real-world graphs
are also given for illustrations.


title:
Design and comparison of two linear controllers with precompensation
  gain for the Quadruple inverted pendulum

abstract:
  In this work we present a workflow for designing two linear control
techniques applied to the dynamic system quadruple inverted pendulum mounted on
a cart (QIP) where the steady state error on cart position is eliminated
through a precompensation gain. The first control law designed was based on
LQR, technique that stabilizes the system states based on a minimization of the
total energy of the system states and the second control technique was pole
placement by 2nd order system approximation, this method allowed to define a
settling time and overshoot of the desired response of the plant, for this
control the system was considered SISO, being the only output of the plant the
horizontal position of the cart. To eliminate the steady-state error generated
by both linear controllers, an analysis of the stationary response of the
system under control in the Laplace Domain was performed. The simulation
environment used to validate the results presented in this paper was Simscape
of Matlab, it is a simulation environment that allowed to simulate the dynamic
of nonlinear mechanical systems. The results obtained indicate that both
controllers are able to stabilize the plant and move the cart position to the
desired setpoint. Finally, we discuss about the performances of both linear
control techniques.


title:
Controllability Analysis of Motion of Artificial Satellite Under the
  Effect of Oblateness of the Earth

abstract:
  In this article we have studied the controllability of artificial satellite
under the effect of zonal harmonic $J_2$ in cylindrical polar coordinates
systems. Seven different cases of thrusters in various directions have been
analyzed and it is found that the system is controllable if we apply thrusters
in either $r$, $\theta$ and $z$ or $\theta$ and $z$ direction. The equations
governing motion of satellite have been linearized and Kalman controllability
test is applied to check the controllability of the system. We have also
derived controller $u$ for the linearized system. The trajectory of the system
have been plotted to show the controllability of the system.


title: Multi-system intervention optimization for interdependent infrastructure

abstract:
  The wellbeing of modern societies is dependent upon the functioning of their
infrastructure networks. This paper introduces the 3C concept, an integrative
multi-system and multi-stakeholder optimization approach for managing
infrastructure interventions (e.g., maintenance, renovation, etc.). The
proposed approach takes advantage of the benefits achieved by grouping (i.e.,
optimizing) intervention activities. Intervention optimization leads to
substantial savings on both direct intervention costs (operator) and indirect
unavailability costs (society) by reducing the number of system interruptions.
The proposed optimization approach is formalized into a structured mathematical
model that can account for the interactions between multiple infrastructure
networks and the impact on multiple stakeholders (e.g., society and
infrastructure operators), and it can accommodate different types of
intervention, such as maintenance, removal, and upgrading. The different types
of interdependencies, within and across infrastructures, are modeled using a
proposed interaction matrix (IM). The IM allows integrating the interventions
of different infrastructure networks whose interventions are normally planned
independently. Moreover, the introduced 3C concept accounts for central
interventions, which are those that must occur at a pre-established time
moment, where neither delay nor advance is permitted. To demonstrate the
applicability of the proposed approach, an illustrative example of a
multi-system and multi-actor intervention planning is introduced. Results show
a substantial reduction in the operator and societal costs. In addition, the
optimal intervention program obtained in the analysis shows no predictable
patterns, which indicates it is a useful managerial decision support tool.