title:
FlowGNN: A Dataflow Architecture for Universal Graph Neural Network
  Inference via Multi-Queue Streaming

abstract:
  Graph neural networks (GNNs) have recently exploded in popularity thanks to
their broad applicability to graph-related problems such as quantum chemistry,
drug discovery, and high energy physics. However, meeting demand for novel GNN
models and fast inference simultaneously is challenging because of the gap
between developing efficient accelerators and the rapid creation of new GNN
models. Prior art focuses on the acceleration of specific classes of GNNs, such
as Graph Convolutional Network (GCN), but lacks the generality to support a
wide range of existing or new GNN models. Meanwhile, most work rely on graph
pre-processing to exploit data locality, making them unsuitable for real-time
applications. To address these limitations, in this work, we propose a generic
dataflow architecture for GNN acceleration, named FlowGNN, which can flexibly
support the majority of message-passing GNNs. The contributions are three-fold.
First, we propose a novel and scalable dataflow architecture, which flexibly
supports a wide range of GNN models with message-passing mechanism. The
architecture features a configurable dataflow optimized for simultaneous
computation of node embedding, edge embedding, and message passing, which is
generally applicable to all models. We also propose a rich library of
model-specific components. Second, we deliver ultra-fast real-time GNN
inference without any graph pre-processing, making it agnostic to dynamically
changing graph structures. Third, we verify our architecture on the Xilinx
Alveo U50 FPGA board and measure the on-board end-to-end performance. We
achieve a speed-up of up to 51-254x against CPU (6226R) and 1.3-477x against
GPU (A6000) (with batch sizes 1 through 1024); we also outperform the SOTA GNN
accelerator I-GCN by 1.03x and 1.25x across two datasets. Our implementation
code and on-board measurement are publicly available on GitHub.


title: Kitaev Chain with a Fractional Twist

abstract:
  The topological non-triviality of insulating phases of matter is by now well
understood through topological K-theory where the indices of the Dirac
operators are assembled into topological classes. We consider in the context of
the Kitaev chain a notion of a generalized Dirac operator where the associated
Clifford algebra is centrally extended. We demonstrate that the central
extension is achieved via taking rational operator powers of Pauli matrices
that appear in the corresponding BdG Hamiltonian. Doing so introduces a
pseudo-metallic component to the topological phase diagram within which the
winding number is valued in $\mathbb Q$. We find that this phase hosts a mode
that remains extended in the presence of weak disorder, motivating a
topological interpretation of a non-integral winding number. We remark that
this is in correspondence with Ref.[J. Differential Geom. 74(2):265-292]
demonstrating that projective Dirac operators defined in the absence of
spin$^\mathbb C$ structure have rational indices.


title:
The X-ray Angular Power Spectrum of Extended Sources in the eROSITA
  Final Equatorial Depth Survey

abstract:
  The eROSITA Final Equatorial Depth Survey (eFEDS), with a sky area of 140
square degrees with depth equivalent to the equatorial patch of the final
eROSITA all-sky survey, represents the largest continuous non full-sky X-ray
fields to-date, making it the premier dataset for measuring the angular power
spectrum. In this work, we measure the X-ray angular power spectrum of galaxy
clusters and groups in the eFEDS field. We show that the measured power
spectrum at large angular scales is consistent with that of the ROSAT All Sky
Survey, as well as the predictions of cluster gas halo model that is calibrated
from Chandra observations of galaxy clusters. At small angular scales, the
eFEDS power spectrum is around an order of magnitude higher than the power
spectrum of the Chandra/COSMOS field, and the halo model prediction. A
follow-up of the impact of point source contamination with the higher angular
resolution instruments like Chandra will resolve this tension. If we restrict
the angular scales where eFEDS power agrees with observations and model
predictions, we show that the X-ray power spectrum from the upcoming eROSITA
all sky data can achieve percent-level constraints on $\Omega_M$ and $\sigma8$,
which are competitive to other cosmological probes.


title:
Seeker: Synergizing Mobile and Energy Harvesting Wearable Sensors for
  Human Activity Recognition

abstract:
  There is an increasing demand for intelligent processing on emerging
ultra-low-power internet of things (IoT) devices, and recent works have shown
substantial efficiency boosts by executing inference tasks directly on the IoT
device (node) rather than merely transmitting sensor data. However, the
computation and power demands of Deep Neural Network (DNN)-based inference pose
significant challenges for nodes in an energy-harvesting wireless sensor
network (EH-WSN). Moreover, these tasks often require responses from multiple
physically distributed EH sensor nodes, which imposes crucial system
optimization challenges in addition to per-node constraints.
  To address these challenges, we propose \emph{Seeker}, a novel approach to
efficiently execute DNN inferences for Human Activity Recognition (HAR) tasks,
using both an EH-WSN and a host mobile device. Seeker minimizes communication
overheads and maximizes computation at each sensor without violating the
quality of service. \emph{Seeker} uses a \emph{store-and-execute} approach to
complete a subset of inferences on the EH sensor node, reducing communication
with the mobile host. Further, for those inferences unfinished because of
harvested energy constraints, it leverages an \emph{activity aware coreset}
(AAC) construction to efficiently communicate compact features to the host
device where ensemble techniques are used to efficiently finish the inferences.
\emph{Seeker} performs HAR with $86.8\%$ accuracy, surpassing the $81.2\%$
accuracy of a state of the art approach. Moreover, by using AAC, it lowers the
communication data volume by $8.9\times$.


title:
Objective crystallographic symmetry classifications of a noisy crystal
  pattern with strong Fedorov type pseudosymmetries and its optimal
  image-quality enhancement

abstract:
  Statistically sound crystallographic symmetry classifications are obtained
with information theory based methods in the presence of approximately Gaussian
distributed noise. A set of three synthetic patterns with strong Fedorov type
pseudosymmetries and varying amounts of noise serve as examples. Contrary to
traditional crystallographic symmetry classifications with an image processing
program such as CRISP, the classification process does not need to be
supervised by a human being and is free of any subjectively set thresholds in
the geometric model selection process. This enables crystallographic symmetry
classification of digital images that are more or less periodic in two
dimensions (2D), a.k.a. crystal patterns, as recorded with sufficient
structural resolution from a wide range of crystalline samples with different
types of scanning probe and transmission electron microscopes. Correct symmetry
classifications enable the optimal crystallographic processing of such images.
That processing consists in the averaging over all asymmetric units in all unit
cells in the selected image area and significantly enhances both the signal to
noise ratio and the structural resolution of a microscopic study of a crystal.
For sufficiently complex crystal patterns, the information-theoretic symmetry
classification methods are more accurate than both visual classifications by
human experts and the recommendations of one of the popular crystallographic
image processing programs of electron crystallography.


title:
Analytical Model of Compact Star with a new version of Modified
  Chaplygin Equation of State

abstract:
  In this paper we found a new model for compact star with anisotropic matter
distribution considering the new version of Chaplygin fluid equation of state
of Errehymy and Daoud (2021). We specify the particular form of the metric
potential proposed for Thirukanesh and Ragel (2012) and generalized for Malaver
(2014) in order to integrate the Einstein`s field equations. The obtained model
satisfies all physical properties expected in a realistic star. The radial
pressure, energy density, metric coefficients, anisotropy and mass are well
defined and are regular in the stellar interior. The results of this research
can be useful in the development and description of new models of compact
structures.


title:
Worst-Case Dynamic Power Distribution Network Noise Prediction Using
  Convolutional Neural Network

abstract:
  Worst-case dynamic PDN noise analysis is an essential step in PDN sign-off to
ensure the performance and reliability of chips. However, with the growing PDN
size and increasing scenarios to be validated, it becomes very time- and
resource-consuming to conduct full-stack PDN simulation to check the worst-case
noise for different test vectors. Recently, various works have proposed machine
learning based methods for supply noise prediction, many of which still suffer
from large training overhead, inefficiency, or non-scalability. Thus, this
paper proposed an efficient and scalable framework for the worst-case dynamic
PDN noise prediction. The framework first reduces the spatial and temporal
redundancy in the PDN and input current vector, and then employs efficient
feature extraction as well as a novel convolutional neural network architecture
to predict the worst-case dynamic PDN noise. Experimental results show that the
proposed framework consistently outperforms the commercial tool and the
state-of-the-art machine learning method with only 0.63-1.02% mean relative
error and 25-69$\times$ speedup.


title:
Hot phonon effects and suppressed Auger recombination on 3 $\mu$m room
  temperature lasing in HgTe-based multiple quantum well diodes

abstract:
  We propose an electrically pumped laser diode based on multiple HgTe quantum
wells with band structure engineered for Auger recombination suppression. A
model for accounting for hot phonons is developed for calculating the
nonequilibrium temperature of electrons and holes. Using a comprehensive model
accounting for carrier drift and diffusion, Auger recombination and hotphonon
effects, we predict of lasing at $\lambda \sim 3 $ $\mu$m at room temperature
in 2.2 nm HgTe/Cd$_{0.85}$Hg$_{0.15}$Te quantum well heterostructure. The
output power in the pulse can reach up to 600 mW for 100 nanosecond-duration
pulses.


title:
Open challenges for Machine Learning based Early Decision-Making
  research

abstract:
  More and more applications require early decisions, i.e. taken as soon as
possible from partially observed data. However, the later a decision is made,
the more its accuracy tends to improve, since the description of the problem to
hand is enriched over time. Such a compromise between the earliness and the
accuracy of decisions has been particularly studied in the field of Early Time
Series Classification. This paper introduces a more general problem, called
Machine Learning based Early Decision Making (ML-EDM), which consists in
optimizing the decision times of models in a wide range of settings where data
is collected over time. After defining the ML-EDM problem, ten challenges are
identified and proposed to the scientific community to further research in this
area. These challenges open important application perspectives, discussed in
this paper.


title:
High-fidelity quantum transduction with long coherence time
  superconducting resonators

abstract:
  We propose a novel quantum transduction hybrid system based on the coupling
of long-coherence time superconducting cavities with electro-optic resonators
to achieve high-efficiency and high-fidelity in quantum communication protocols
and quantum sensing. \copyright 2022 The Author(s)


title:
Fuzzballs and Microstate Geometries: Black-Hole Structure in String
  Theory

abstract:
  The black-hole information paradox provides one of the sharpest foci for the
conflict between quantum mechanics and general relativity and has become the
proving-ground of would-be theories of quantum gravity. String theory has made
significant progress in resolving this paradox, and has led to the fuzzball and
microstate geometry programs. The core principle of these programs is that
horizons and singularities only arise if one tries to describe gravity using a
theory that has too few degrees of freedom to resolve the physics. String
theory has sufficiently many degrees of freedom and this naturally leads to
fuzzballs and microstate geometries: The reformation of black holes into
objects with neither horizons nor singularities. This not only resolves the
paradox but provides new insights into the microstructure of black holes. We
summarize the current status of this approach and describe future prospects and
additional insights that are now within reach. This paper is an expanded
version of our Snowmass White Paper arXiv:2203.04981.


title: The stellar mass distribution of the Milky Way's bar: an analytic model

abstract:
  We present an analytic model of the stellar mass distribution of the Milky
Way bar. The model is obtained by fitting a multi-component parametric density
distribution to a made-to-measure N-body model of Portail et al., constructed
to match a variety of density and kinematics observational data. The analytic
model reproduces in detail the 3D density distribution of the N-body bar
including the X-shape. The model and the gravitational potential it generates
are available as part of the software package AGAMA for galactic dynamics, and
can be readily used for orbit integrations, hydrodynamical simulations or other
applications.


title: A Database of Calabi-Yau Orientifolds and the Size of D3-Tadpoles

abstract:
  The classification of 4D reflexive polytopes by Kreuzer and Skarke allows for
a systematic construction of Calabi-Yau hypersurfaces as fine, regular, star
triangulations (FRSTs). Until now, the vastness of this geometric landscape
remains largely unexplored. In this paper, we construct Calabi-Yau orientifolds
from holomorphic reflection involutions of such hypersurfaces with Hodge
numbers $h^{1,1}\leq 12$. In particular, we compute orientifold configurations
for all favourable FRSTs for $h^{1,1}\leq 7$, while randomly sampling
triangulations for each pair of Hodge numbers up to $h^{1,1}=12$. We find
explicit string compactifications on these orientifolded Calabi-Yaus for which
the D3-charge contribution coming from O$p$-planes grows linearly with the
number of complex structure and K\"ahler moduli. We further consider non-local
D7-tadpole cancellation through Whitney branes. We argue that this leads to a
significant enhancement of the total D3-tadpole as compared to conventional
$\mathrm{SO}(8)$ stacks with $(4+4)$ D7-branes on top of O7-planes. In
particular, before turning-on worldvolume fluxes, we find that the largest
D3-tadpole in this class occurs for Calabi-Yau threefolds with
$(h^{1,1}_{+},h^{1,2}_{-})=(11,491)$ with D3-brane charges
$|Q_{\text{D3}}|=504$ for the local D7 case and $|Q_{\text{D3}}|=6,664$ for the
non-local Whitney branes case, which appears to be large enough to cancel
tadpoles and allow fluxes to stabilise all complex structure moduli. Our data
is publicly available under
http://github.com/AndreasSchachner/CY_Orientifold_database .


title:
Unconventional Self-Similar Hofstadter Superconductivity from Repulsive
  Interactions

abstract:
  The interplay of lattice potential and magnetic field gives rise to fractal
Hofstadter bands that have long been associated with quantum Hall phenomena. In
this work, we show that Hofstadter bands are also a rich platform to realize
unconventional superconductivity driven entirely by repulsive interactions.
Unlike Landau levels, Hofstadter bands have finite bandwidth and display a rich
manifold of Van Hove singularities, whose number can be tuned as a function of
the magnetic flux $\Phi = 2\pi (p/q)(\hbar/e)$ per unit cell. Exploring this
control knob, we perform a weak coupling renormalization group (RG) analysis
for the fermionic Hofstadter-Hubbard model on a square lattice, which
establishes a rich competition of electronic orders, from which electronic
pairing emerges as a low energy instability. Remarkably, some of these fixed
points are characterized by an emergent self-similarity, which reflects the
non-trivial renormalization of the bare Hubbard interaction in fractal
Hofstadter bands. Our main predictions are (i) nodal d-wave superconductivity
near $1/4$ and $3/4$ fillings in the $\pi$-flux lattice ($\Phi = h/2e$); (ii)
chiral topological superconductivity with Chern number $\mathcal{C} = \pm 6$
near $1/6$ and $5/6$ fillings in the $\pm 2\pi/3$-flux lattice ($\Phi = \pm
h/3e$). The latter arises when the interactions flow to a self-similar fixed
trajectory of the RG flow and are characterized by a self-similarity symmetry
that enforces a polynomially decaying real space order parameter. Our work
opens a new route in the pursuit of reentrant superconductivity in a wide class
of Hofstadter quantum materials including synthetic lattices and moir\'e
heterostructures.


title: Dust formation in the outflows of catastrophically evaporating planets

abstract:
  Ultra-short period planets offer a window into the poorly understood interior
composition of exoplanets through material evaporated from their rocky
interiors. Among these objects are a class of disintegrating planets, observed
when their dusty tails transit in front of their host stars. These dusty tails
are thought to originate from dust condensation in thermally-driven winds from
the sublimating surfaces of these planets. Existing models of these winds have
been unable to explain their highly variable nature or explain how dust forms
in the wind - through which these systems were originally detected. Here we
present new radiation-hydrodynamic simulations of the winds from these planets,
including a model for formation and destruction of dust. We find that dust
forms readily in the winds, a consequence of large dust grains obtaining lower
temperatures than the planet's surface. Furthermore, we find that the coupling
of the planet's surface temperature to the outflow properties via the dust
opacity can drive time-variable flows when dust condensation is sufficiently
fast. In agreement with previous work, our models suggest that these dusty
tails are a signature of catastrophically evaporating planets that are close to
the end of their lives. Finally, we discuss the implications of our results for
the dust's composition, but more detailed hydrodynamic models that
self-consistently compute the composition of the dust and gas are warranted to
link the dust properties to the planet's interior composition.


title:
A new technique to determine a pulsar period: the waterfall principal
  component analysis

abstract:
  This paper describes a new technique for determining the optimal period of a
pulsar and consequently its light curve. The implemented technique makes use of
the Principal Component Analysis (PCA) applied to the so-called waterfall
diagram, which is a bidimensional representation of the pulsar acquired data.
In this context we have developed the python package pywpf to easily retrieve
the period with the presented method. We applied this technique to sets of data
of the brightest pulsars in visible light that we obtained with the fast photon
counter Iqueye. Our results are compared with those obtained by different and
more classical analyses (e.g., epoch folding), showing that the periods so
determined agree within the errors, and that the errors associated to the
waterfall-PCA folding technique are slightly smaller than those obtained by the
$\chi^2$ epoch folding technique. We also simulated extremely noisy situations,
showing that by means of a new merit function associated to the waterfall-PCA
folding it is possible to get more confidence on the determined period with
respect to the $\chi^2$ epoch folding technique.


title: Gauge invariance from on-shell massive amplitudes and tree unitarity

abstract:
  We study the three-particle and four-particle scattering amplitudes for an
arbitrary, finite number of massive scalars, spinors and vectors by employing
the on-shell massive spinor formalism. We consider the most general
three-particle amplitudes with energy growing behavior at most of $\mathcal{O}
(E)$. This is the special case of the requirement of tree unitarity, which
states that the $N$-particle scattering amplitudes at tree-level should grow at
most as $\mathcal{O} (E^{4-N})$ in the high energy hard scattering limit, i.e.
at fixed non-zero angles. Then the factorizable parts of the four-particle
amplitudes are calculated by gluing the on-shell three-particle amplitudes
together and utilizing the fact that tree-level amplitudes have only simple
poles. The contact parts of the four-particle amplitudes are further determined
by tree unitarity, which also puts strong constraints on the possible allowed
three-particle coupling constants and the masses. The derived relations among
them converge to the predictions of gauge invariance in the UV theory. This
provides a purely on-shell understanding of spontaneously broken gauge
theories.


title: First principles determination of bubble wall velocity

abstract:
  The terminal wall velocity of a first-order phase transition bubble can be
calculated from a set of fluid equations describing the scalar fields and the
plasma's state. We rederive these equations from the energy-momentum tensor
conservation and the Boltzmann equation, without linearizing in the background
temperature and fluid velocity. The resulting equations have a finite solution
for any wall velocity. We propose a spectral method to integrate the Boltzmann
equation, which is simple, efficient and accurate. As an example, we apply this
new methodology to the singlet scalar extension of the standard model. We find
that all solutions are naturally categorized as deflagrations ($v_w\sim c_s$)
or ultrarelativistic detonations ($\gamma_w\gtrsim10$). Furthermore, the
contributions from out-of-equilibrium effects are, most of the time,
subdominant. Finally, we use these results to propose several approximation
schemes with increasing levels of complexity and accuracy. They can be used to
considerably simplify the methodology while correctly describing the
qualitative behavior of the bubble wall.


title:
Moments for positivity: using Drell-Yan data to test positivity bounds
  and reverse-engineer new physics

abstract:
  Moments of the leptonic angular distribution in the Drell-Yan process have
recently been shown to be sensitive probes of a specific class of dimension-8,
four-fermion operators in the Standard Model Effective Field Theory, involving
a pair of quarks and leptons. The same operators are also subject to positivity
bounds, when requiring the associated (unknown) UV completion to obey basic
principles of quantum field theory. We perform a phenomenological study to
quantify the sensitivity of the high-luminosity LHC to this set of operators
and, by extension, the positivity bounds. We further extend the angular basis
of moments and consider double differential information to improve the ability
to disentangle the different operators, leading to a sensitivity to new physics
scales up to 3 TeV. We use this information to explore the violation of
positivity at the LHC as a way to test the underlying principles of quantum
field theory. Finally, we present a case study which combines our results with
information from other (current and prospective) experiments, as well as the
positivity cone to infer the properties of possible tree-level UV completions.
The data lead to robust, model-independent lower bounds on the $M/\sqrt{g}$
combination of the particle mass and coupling, for states that couple to
right-handed leptons and/or up quarks.


title:
Nontrivial spatial behavior of the Gauss-Bonnet curvature invariant of
  rapidly-rotating Kerr black holes

abstract:
  The Gauss-Bonnet curvature invariant has attracted the attention of
physicists and mathematicians over the years. In particular, it has recently
been proved that black holes can support external matter configurations that
are non-minimally coupled to the Gauss-Bonnet invariant of the curved
spacetime. Motivated by this physically interesting behavior of black holes in
Einstein-Gauss-Bonnet theories, we present a detailed {\it analytical} study of
the physical and mathematical properties of the Gauss-Bonnet curvature
invariant ${\cal G}_{\text{Kerr}}(r,\cos\theta;a/M)$ of spinning Kerr black
holes in the spacetime region outside the horizon. Interestingly, we prove
that, for all spinning Kerr spacetimes in the physically allowed regime
$a/M\in[0,1]$, the spin-dependent maximum curvature of the Gauss-Bonnet
invariant is attained at the equator of the black-hole surface. Intriguingly,
we reveal that the location of the global minimum of the Gauss-Bonnet invariant
has a highly non-trivial functional dependence on the black-hole rotation
parameter: (i) For Kerr black holes in the dimensionless slow-rotation
$a/M<(a/M)^{-}_{\text{crit}}=1/2$ regime, the Gauss-Bonnet curvature invariant
attains its global minimum asymptotically at spatial infinity, (ii) for black
holes in the intermediate spin regime $1/2=(a/M)^{-}_{\text{crit}}\leq
a/M\leq(a/M)^{+}_{\text{crit}}=
\sqrt{\Big\{{{7+\sqrt{7}\cos\Big[3^{-1}\arctan\big(3\sqrt{3}\big)\Big]-
\sqrt{21}\sin\Big[3^{-1}\arctan\big(3\sqrt{3}\big)\Big]\Big\}}/12}}$, the
global minima are located at the black-hole poles, and (iii) Kerr black holes
in the super-critical regime $a/M>(a/M)^{+}_{\text{crit}}$ are characterized by
a non-trivial functional behavior of the Gauss-Bonnet curvature invariant along
the black-hole horizon with a spin-dependent polar angle for the global minimum
point.


title: Cosmic strings from pure Yang-Mills theory

abstract:
  We discuss the formation of cosmic strings or macroscopic color flux tubes at
the phase transition from the deconfinement to confinement phase in pure
Yang-Mills (YM) theory, such as SU($N$), Sp($N$), SO($N$), and Spin($N$), based
on the current understanding of theoretical physics. According to the
holographic dual descriptions, the cosmic strings are dual to fundamental
strings or wrapped D-branes in the gravity side depending on the structure of
the gauge group, and the reconnection probability is suppressed by
$\mathcal{O}(N^{-2})$ and $e^{-\mathcal{O}(N)}$, respectively. The pure YM
theory thus provides a simple realization of cosmic F- and D-strings without
the need for a brane-inflationary scenario or extra dimension. We also review
the stability of cosmic strings based on the concept of 1-form symmetry, which
further implies the existence of a baryon vertex in some YM theory. We
calculate the gravitational wave spectrum that is emitted from the cosmic
strings based on an extended velocity-dependent one-scale model and discuss its
detectability based on ongoing and planned gravitational-wave experiments. In
particular, the SKA and LISA can observe gravitational signals if the
confinement scale is higher than $\mathcal{O}(10^{12})\,\mathrm{GeV}$ and
$\mathcal{O}(10^{10})\,\mathrm{GeV}$ for SU($N$) with $N = \mathcal{O}(1)$,
respectively.


title: A Quantum-Mechanical Mechanism for Reducing the Cosmological Constant

abstract:
  We exhibit a mechanism which dynamically adjusts cosmological constant toward
$0^+$. The adjustment is quantum-mechanical, discharging cosmological constant
in random discrete steps. It renders de Sitter space unstable, and triggers its
decay toward Minkowski. Since the instability dynamically stops at $\Lambda =
0$, the evolution favors the terminal Minkowski space without a need for
anthropics. The mechanism works for any QFT coupled to gravity.


title: Cosmic F- and D-strings from pure Yang-Mills theory

abstract:
  We discuss the formation of cosmic strings or macroscopic color flux tubes
after the deconfinement/confinement phase transition in the pure Yang-Mills
theory. Based on holographic dual descriptions, these cosmic strings can be
interpreted as fundamental (F-) strings or wrapped D-branes (which we call as
D-strings) in the gravity side, depending on the structure of the gauge group.
In fact, the reconnection probabilities of the F- and D-strings are suppressed
by factors of $1/N^2$ and $e^{-c N}$, where $c = \mathcal{O}(1)$, in a
large-$N$ limit, respectively. Supported by the picture of electric-magnetic
duality, we discuss that color flux tubes form after the
deconfinement/confinement phase transition, just like the formation of local
cosmic strings after spontaneous symmetry breaking in the weak-U(1) gauge
theory. We use an extended velocity-dependent one-scale model to describe the
dynamics of the string network and calculate the gravitational wave signals
from string loops.


title: Quantum evolution of the Hawking state for black holes

abstract:
  We give a general description of the evolving quantum state of a
Schwarzschild black hole, in the quantum field theory approximation. Such a
time-dependent description is based on introducing a choice of time slices. We
in particular consider slices that smoothly cross the horizon, and introduction
of "stationary" such slices simplifies the analysis. This analysis goes beyond
standard derivations of Hawking radiation that focus on asymptotic excitations,
and in particular gives an evolving state that is regular at the horizon, with
no explicit transplanckian dependence, and that can in principle be generalized
to incorporate interacting fields. It is also expected to be useful in
connecting to information-theoretic investigation of black hole evolution. The
description of the evolving state depends on the choice of slices as well as
coordinates on the slices and mode bases; these choices give different
"pictures" analogous to that of Schr\"odinger. Evolution does have a simpler
appearance in an energy eigenbasis, but such a basis is also singular at the
horizon; evolution of regular modes has a more complicated appearance, whose
properties may be inferred by comparing with the energy eigenbasis. In a
regular description, Hawking quanta are produced in a black hole atmosphere, at
scales comparable to the horizon size. This approach is also argued to extend
to more general asymptotics, such as that of anti de Sitter space. In the
latter context, this analysis provides a description of the hamiltonian and
evolution of a black hole that may be compared to the large-$N$ dynamics of the
proposed dual CFT.


title: Polarization power spectra and dust cloud morphology

abstract:
  In the framework of studies of the CMB polarization and its Galactic
foregrounds, the angular power spectra of thermal dust polarization maps have
revealed an intriguing E/B asymmetry and a positive TE correlation. In
interpretation studies of these observations, magnetized ISM dust clouds have
been treated as filamentary structures only; however, sheet-like shapes are
also supported by observational and theoretical evidence. In this work, we
study the influence of cloud shape and its connection to the local magnetic
field on angular power spectra of thermal dust polarization maps. We simulate
realistic filament-like and sheet-like interstellar clouds, and generate
synthetic maps of their thermal dust polarized emission using the software
$Asterion$. We compute their polarization power spectra in multipole range
$\ell \in [100,500]$ and quantify the E/B power asymmetry through the $R_{EB}$
ratio, and the correlation coefficient $r^{TE}$ between T and E modes. We
quantify the dependence of $R_{EB}$ and $r^{TE}$ values on the offset angle
(between longest cloud axis and magnetic field) and inclination angle (between
line-of-sight and magnetic field) for both cloud shapes embedded either in a
regular or a turbulent magnetic field. We find that both cloud shapes cover the
same regions of the ($R_{EB}$, $r^{TE}$) parameter space. The dependence on
inclination and offset angles are similar for both shapes although sheet-like
structures generally show larger scatter. In addition to the known dependence
on the offset angle, we find a strong dependence of $R_{EB}$ and $r^{TE}$ on
the inclination angle. The fact that filament-like and sheet-like structures
may lead to polarization power spectra with similar ($R_{EB}$, $r^{TE}$) values
complicates their interpretation. In future analyses, this degeneracy should be
accounted for as well as the connection to the magnetic field geometry.


title: Restoring quantum communication efficiency over high loss optical fibres

abstract:
  In the absence of quantum repeaters, quantum communication proved to be
nearly impossible across optical fibres longer than $\gtrsim 20\text{ km}$ due
to the drop of transmissivity below the critical threshold of $1/2$. However,
if the signals fed into the fibre are separated by a sufficiently short time
interval, memory effects must be taken into account. In this paper we show that
by properly accounting for these effects it is possible to devise schemes that
enable unassisted quantum communication across arbitrarily long optical fibres
at a fixed positive qubit transmission rate. We also demonstrate how to achieve
entanglement-assisted communication over arbitrarily long distances at a rate
of the same order of the maximum achievable in the unassisted noiseless case.


title:
Quantum Optical Communication in the presence of strong attenuation
  noise

abstract:
  Is quantum communication possible over an optical fibre with transmissivity
$\lambda\leq 1/2$ ? The answer is well known to be negative if the environment
with which the incoming signal interacts is initialised in a thermal state.
However, in [PRL 125:110504, 2020] the quantum capacity was found to be always
bounded away from zero for all $\lambda>0$, a phenomenon dubbed "die-hard
quantum communication" (D-HQCOM), provided that the initial environment state
can be chosen appropriately (depending on $\lambda$). Here we show an even
stronger version of D-HQCOM in the context of entanglement-assisted classical
communication: entanglement assistance and control of the environment enable
communication with performance at least equal to that of the ideal case of
absence of noise, even if $\lambda>0$ is arbitrarily small. These two phenomena
of D-HQCOM have technological potential provided that we are able to control
the environment. How can we achieve this? Our second main result answers this
question. Here we provide a fully consistent protocol to activate the phenomena
of D-HQCOM without directly accessing the environment state. This is done by
sending over the channel "trigger signals", i.e. signals which do not encode
information, prior to the actual communication, with the goal of modifying the
environment in an advantageous way. This is possible thanks to the memory
effects which arise when the sender feeds signals separated by a sufficiently
short temporal interval. Our results may offer a concrete scheme to communicate
across arbitrarily long optical fibres, without using quantum repeaters. As a
by-product of our analysis, we derive a simple Kraus representation of the
thermal attenuator exploiting the associated Lindblad master equation.


title: Unitarity bounds for all symmetry-constrained 3HDMs

abstract:
  Models with three Higgs doublets (3HDM) are the source of much recent
activity, for they are key components of many solutions to the problems of the
Standard Model; from extra sources of CP violation to Dark Matter candidates.
We compute explicitly the theoretical bounds for all symmetry-constrained 3HDM
arising from the perturbative unitarity of two-to-two scattering amplitudes. In
addition, we propose a method based on principal minors that foregoes
diagonalization and which is preferable in all models (not only 3HDM) dealing
with large scattering matrices.


title:
Accurate Model of the Projected Velocity Distribution of Galaxies in
  Dark Matter Halos

abstract:
  We present a percent-level accurate model of the line-of-sight velocity
distribution of galaxies around dark matter halos as a function of projected
radius and halo mass. The model is developed and tested using synthetic galaxy
catalogs generated with the UniverseMachine run on the Multi-Dark Planck 2
N-body simulations. The model decomposes the galaxies around a cluster into
three kinematically distinct classes: orbiting, infalling, and interloping
galaxies. We demonstrate that: 1) we can statistically distinguish between
these three types of galaxies using only projected line-of-sight velocity
information; 2) the halo edge radius inferred from the line-of-sight velocity
dispersion is an excellent proxy for the three-dimensional halo edge radius; 3)
we can accurately recover the full velocity dispersion profile for each of the
three populations of galaxies. Importantly, the velocity dispersion profiles of
the orbiting and infalling galaxies contain five independent parameters --
three distinct radial scales and two velocity dispersion amplitudes -- each of
which is correlated with mass. Thus, the velocity dispersion profile of galaxy
clusters has inherent redundancies that allow us to perform nontrivial
systematics check from a single data set. We discuss several potential
applications of our new model for detecting the edge radius and constraining
cosmology and astrophysics using upcoming spectroscopic surveys.


title:
HRDA: Context-Aware High-Resolution Domain-Adaptive Semantic
  Segmentation

abstract:
  Unsupervised domain adaptation (UDA) aims to adapt a model trained on the
source domain (e.g. synthetic data) to the target domain (e.g. real-world data)
without requiring further annotations on the target domain. This work focuses
on UDA for semantic segmentation as real-world pixel-wise annotations are
particularly expensive to acquire. As UDA methods for semantic segmentation are
usually GPU memory intensive, most previous methods operate only on downscaled
images. We question this design as low-resolution predictions often fail to
preserve fine details. The alternative of training with random crops of
high-resolution images alleviates this problem but falls short in capturing
long-range, domain-robust context information. Therefore, we propose HRDA, a
multi-resolution training approach for UDA, that combines the strengths of
small high-resolution crops to preserve fine segmentation details and large
low-resolution crops to capture long-range context dependencies with a learned
scale attention, while maintaining a manageable GPU memory footprint. HRDA
enables adapting small objects and preserving fine segmentation details. It
significantly improves the state-of-the-art performance by 5.5 mIoU for
GTA-to-Cityscapes and 4.9 mIoU for Synthia-to-Cityscapes, resulting in
unprecedented 73.8 and 65.8 mIoU, respectively. The implementation is available
at https://github.com/lhoyer/HRDA.


title:
Modest holography and bulk reconstruction in asymptotically flat
  spacetimes

abstract:
  In this work we present a "modest" holographic reconstruction of the bulk
geometry in asymptotically flat spacetime using the two-point correlators of
boundary quantum field theory (QFT) in asymptotically flat spacetime. The
boundary QFT lives on the null boundary of the spacetime, namely null infinity
and/or the Killing horizons. The bulk reconstruction relies on two unrelated
results: (i) there is a bulk-to-boundary type correspondence between free
quantum fields living in the bulk manifold and free quantum fields living on
its null boundary, and (ii) one can construct the metric by making use of the
Hadamard expansion of the field living in the bulk. This holographic
reconstruction is "modest" in that the fields used are non-interacting and not
strong-weak holographic duality in the sense of AdS/CFT, but it works for
generic asymptotically flat spacetime subject to some reasonably mild
conditions.


title:
Prospects for a flavour violating $Z^\prime$ explanation of $\Delta
  a_{\mu,e}$

abstract:
  The apparent tensions emerging from the comparison of experimental data of
the anomalous magnetic moments of the muon and electron to the Standard Model
predictions ($\Delta a_{\mu,e}$) could be interpreted as a potential signal of
New Physics. Models encompassing a light vector boson have been known to offer
a satisfactory explanation to $\Delta a_{\mu}$, albeit subject to stringent
experimental constraints. Here we explore a minimal extension of the Standard
Model via a leptophilic vector boson $Z^\prime$, under the hypothesis of
strictly flavour-violating couplings of the latter to leptons. The most
constraining observables to this ad-hoc construction emerge from lepton flavour
universality violation (in $Z$ and $\tau$ decays) and from rare charged lepton
flavour violating transitions. Once these are accommodated, one can saturate
the tensions in $\Delta a_{\mu}$, but $\Delta a_{e}$ is predicted to be
Standard Model-like. We infer prospects for several observables, including
leptonic $Z$ decays and several charged lepton flavour violating processes. We
also discuss potential signatures of the considered $Z^\prime$ at a future muon
collider, emphasising the role of the $\mu^+\mu^- \to\tau^+\tau^- $
forward-backward asymmetry as a key probe of the model.


title:
Timing and Multi-Channel: Novel Method for Determining the Neutrino Mass
  Ordering from Supernovae

abstract:
  One of the few remaining unknowns in the standard three-flavor neutrino
oscillation paradigm is the ordering of neutrino masses. In this work we
propose a novel method for determining neutrino mass ordering using the time
information on early supernova neutrino events. In a core-collapse supernova,
neutrinos are produced earlier than antineutrinos and, depending on the mass
ordering which affects the adiabatic flavor evolution, may cause earlier
observable signals in $\nu_e$ detection channels than in others. Hence, the
time differences are sensitive to the mass ordering. We find that using the
time information on the detection of the first galactic supernova events at
future detectors like DUNE, JUNO and Hyper-Kamiokande, the mass ordering can
already be determined at 2$\sigma$ CL, while $\mathcal{O}(10)$ events suffice
for the discovery. Our method does not require high-statistics and could be
used within the supernova early warning system (SNEWS) which will have access
to the time information on early supernova neutrino events recorded in a number
of detectors. The method proposed in this paper also implies a crucial
interplay between the mass ordering and the triangulation method for locating
supernovae.


title: On robustness and related properties on toric ideals

abstract:
  A toric ideal is called robust if its universal Gr\"obner basis is a minimal
set of generators, and is called generalized robust if its universal Gr\"obner
basis equals its universal Markov basis (the union of all its minimal sets of
binomial generators). Robust and generalized robust toric ideals are both
interesting from both a Commutative Algebra and an Algebraic Statistics
perspective. However, only a few nontrivial examples of such ideals are known.
In this work we study these properties for toric ideals of both graphs and
numerical semigroups. For toric ideals of graphs, we characterize
combinatorially the graphs giving rise to robust and to generalized robust
toric ideals generated by quadratic binomials. As a byproduct, we obtain
families of Koszul rings. For toric ideals of numerical semigroups, we
determine that one of its initial ideals is a complete intersection if and only
if the semigroup belongs to the so-called family of free numerical semigroups.
Hence, we characterize all complete intersection numerical semigroups which are
minimally generated by one of its Gr\"obner basis and, as a consequence, all
the Betti numbers of the toric ideal and its corresponding initial ideal
coincide. Moreover, also for numerical semigroups, we prove that the ideal is
generalized robust if and only if the semigroup has a unique Betti element and
that there are only trivial examples of robust ideals. We finish the paper with
some open questions.


title:
A Generalized Kyle-Back Strategic Insider Trading Model with Dynamic
  Information

abstract:
  In this paper we consider a class of generalized Kyle-Back strategic insider
trading models in which the insider is able to use the dynamic information
obtained by observing the instantaneous movement of an underlying asset that is
allowed to be influenced by its market price. Since such a model will be
largely outside the Gaussian paradigm, we shall try to Markovize it by
introducing an auxiliary diffusion process, in the spirit of the weighted total
order process of, e.g., \cite{CCD11}, as a part of the "pricing rule". As the
main technical tool in solving the Kyle-Back equilibrium, we study a class of
Stochastic Two-Point Boundary Value Problem (STPBVP), which resembles the
dynamic Markovian bridge in the literature, but without insisting on its local
martingale requirement. In the case when the solution of the STPBVP has an
affine structure, we show that the pricing rule functions, whence the Kyle-Back
equilibrium, can be determined by the decoupling field of a forward-backward
SDE obtained via a non-linear filtering approach, along with a set of
compatibility conditions.


title:
Post-deposition annealing and interfacial ALD buffer layers of
  Sb$_2$Se$_3$/CdS stacks for reduced interface recombination and increased
  open-circuit voltages

abstract:
  Currently, Sb$_2$Se$_3$ thin films receive considerable research interest as
a solar cell absorber material. When completed into a device stack, the major
bottleneck for further device improvement is the open circuit voltage, which is
the focus of the work presented here. Polycrystalline thin film Sb$_2$Se$_3$
absorbers and solar cells are prepared in substrate configuration and the
dominant recombination path is studied using photoluminescence spectroscopy and
temperature dependent current-voltage characteristics. It is found that a
post-deposition annealing after the CdS buffer layer deposition can effectively
remove interface recombination since the activation energy of the dominant
recombination path becomes equal to the bandgap of the Sb$_2$Se$_3$ absorber.
The increased activation energy is accompanied by an increased
photoluminescence yield, i.e. reduced non-radiative recombination. Finished
Sb$_2$Se$_3$ solar cell devices reach open circuit voltages as high as 485 mV.
Contrarily, the short-circuit current density of these devices is limiting the
efficiency after the post-deposition annealing. It is shown that atomic layer
deposited intermediate buffer layers such as TiO$_2$ or Sb$_2$Se$_3$ can pave
the way for overcoming this limitation.


title: Investigating Top-Higgs FCNC Couplings at the FCC-hh

abstract:
  We have studied the sensitivity to flavor changing neutral current
interaction of top and Higgs boson at the future circular collider in the
hadron-hadron collision mode (FCC-hh). Our main concerns are the processes of
$pp\rightarrow th$ (FCNC production) and $pp\rightarrow t\bar{t}$ (one top FCNC
decay) which contributes to the single lepton, at least three jets and the
missing energy transverse in the final state. On the one hand FCC-hh offers
very high luminosity and large cross section for these signal processes, on the
other hand signal can be distinguished from background which needs application
of ingenious methods. Here, we have inspired and followed the searches at the
LHC using our analysis path and enhanced attainable limits obtained on the
possible top-Higgs FCNC couplings phenomenologically. We obtain new limits
which are beyond the current experimental limits obtained from different
channels and processes at the LHC. The potential discovery or exclusion limits
on branching ratios for $tqH$ FCNC interactions can be set
$BR(\eta_{uc})_{\mathrm{disc}}=1.32\times10^{-5}$ or
$BR(\eta_{uc})_{\mathrm{exc}}=2.78\times10^{-6}$ at an integrated luminosity of
30 ab$^{-1}$ , respectively. Our results are compatible with the other channels
already studied at FCC-hh.


title: Termination Shocks and the Extended X-ray Emission in MRK 78

abstract:
  Sub-arcsecond imaging of the X-ray emission in the type 2 AGN Mrk 78 with
Chandra shows complex structure with spectral variations on scales from
$\sim$200 pc to $\sim$ 2 kpc. Overall the X-ray emission is aligned E-W with
the radio (3.6 cm) and narrow emission line region as mapped in [OIII], with a
marked E-W asymmetry. The Eastern X-ray emission is mostly in a compact knot
coincident with the location where the radio source is deflected, while the
Western X-ray emission forms a loop or shell $\sim$2 kpc from the nucleus with
radius $\sim$0.7 kpc. There is suggestive evidence of shocks in both the
Eastern knot and the Western arc. Both these positions coincide with large
changes in the velocities of the [OIII] outflow. We discuss possible reasons
why the X-ray shocks on the Western side occur $\sim1$ kpc farther out than on
the Eastern side. We estimate that the thermal energy injected by the shocks
into the interstellar medium corresponds to $0.05-0.6$% of the AGN bolometric
luminosity.


title: An Improved Nearest Neighbour Classifier

abstract:
  A windowed version of the Nearest Neighbour (WNN) classifier for images is
described. While its construction is inspired by the architecture of Artificial
Neural Networks, the underlying theoretical framework is based on approximation
theory. We illustrate WNN on the datasets MNIST and EMNIST of images of
handwritten digits. In order to calibrate the parameters of WNN, we first study
it on the classical MNIST dataset. We then apply WNN with these parameters to
the challenging EMNIST dataset. It is demonstrated that WNN misclassifies 0.42%
of the images of EMNIST and therefore significantly outperforms predictions by
humans and shallow ANNs that both have more than 1.3% of errors.


title:
ForeSight: Reducing SWAPs in NISQ Programs via Adaptive Multi-Candidate
  Evaluations

abstract:
  Near-term quantum computers are noisy and have limited connectivity between
qubits. Compilers are required to introduce SWAP operations in order to perform
two-qubit gates between non-adjacent qubits. SWAPs increase the number of gates
and depth of programs, making them even more vulnerable to errors. Moreover,
they relocate qubits which affect SWAP selections for future gates in a
program. Thus, compilers must select SWAP routes that not only minimize the
overheads for the current operation, but also for future gates. Existing
compilers tend to select paths with the fewest SWAPs for the current
operations, but do not evaluate the impact of the relocations from the selected
SWAP candidate on future SWAPs. Also, they converge on SWAP candidates for the
current operation and only then decide SWAP routes for future gates, thus
severely restricting the SWAP candidate search space for future operations.
  We propose ForeSight, a compiler that simultaneously evaluates multiple SWAP
candidates for several operations into the future, delays SWAP selections to
analyze their impact on future SWAP decisions and avoids early convergence on
sub-optimal candidates. Moreover, ForeSight evaluates slightly longer SWAP
routes for current operations if they have the potential to reduce SWAPs for
future gates, thus reducing SWAPs for the program globally. As compilation
proceeds, ForeSight dynamically adds new SWAP candidates to the solution space
and eliminates the weaker ones. This allows ForeSight to reduce SWAP overheads
at program-level while keeping the compilation complexity tractable. Our
evaluations with a hundred benchmarks across three devices show that ForeSight
reduces SWAP overheads by 17% on average and 81% in the best-case, compared to
the baseline. ForeSight takes minutes, making it scalable to large programs.


title: On the Complexity of Half-Guarding Monotone Polygons

abstract:
  We consider a variant of the art gallery problem where all guards are limited
to seeing to the right inside a monotone polygon. We call such guards:
half-guards. We provide a polynomial-time approximation for point guarding the
entire monotone polygon. We improve the best known approximation of 40 from
[11], to 8. We also provide an NP-hardness reduction for point guarding a
monotone polygon with half-guards.


title: Proximal Causal Inference for Marginal Counterfactual Survival Curves

abstract:
  Contrasting marginal counterfactual survival curves across treatment arms is
an effective and popular approach for inferring the causal effect of an
intervention on a right-censored time-to-event outcome. A key challenge to
drawing such inferences in observational settings is the possible existence of
unmeasured confounding, which may invalidate most commonly used methods that
assume no hidden confounding bias. In this paper, rather than making the
standard no unmeasured confounding assumption, we extend the recently proposed
proximal causal inference framework of Miao et al. (2018), Tchetgen et al.
(2020), Cui et al. (2020) to obtain nonparametric identification of a causal
survival contrast by leveraging observed covariates as imperfect proxies of
unmeasured confounders. Specifically, we develop a proximal inverse
probability-weighted (PIPW) estimator, the proximal analog of standard IPW,
which allows the observed data distribution for the time-to-event outcome to
remain completely unrestricted. PIPW estimation relies on a parametric model
for a so-called treatment confounding bridge function relating the treatment
process to confounding proxies. As a result, PIPW might be sensitive to model
misspecification. To improve robustness and efficiency, we also propose a
proximal doubly robust estimator and establish uniform consistency and
asymptotic normality of both estimators. We conduct extensive simulations to
examine the finite sample performance of our estimators, and proposed methods
are applied to a study evaluating the effectiveness of right heart
catheterization in the intensive care unit of critically ill patients.


title:
Electroweak Corrections to Dark Matter Direct Detection in the Dark
  Singlet Phase of the N2HDM

abstract:
  Direct detection experiments are the only way to obtain indisputable evidence
of the existence of dark matter (DM) in the form of a particle. These
experiments have been used to probe many extensions of the Standard Model (SM)
that provide DM candidates. Experimental results like the latest ones from
XENON1T lead to severe constraints in the parameter space of many of the
proposed models. In a simple extension of the SM, the addition of a complex
singlet to the SM content, one-loop corrections need to be taken into account
because the tree-level cross section is proportional to the DM velocity, and
therefore negligible. In this work we study the case of a DM particle with
origin in a singlet but in a larger framework of an extension by an extra
doublet together with the extra singlet providing the DM candidate. We show
that in the region of interest of the present and future direct detection
experiments, electroweak corrections are quite stable with a $K$-factor very
close to one.


title: Dimensional Reduction of B-Fields in F-theory

abstract:
  We describe the dimensional reduction of the IIB B-fields in F-theory using a
conjectured description of normalizable B-fields in terms of perverse sheaves.
Computations are facilitated using the Decomposition Theorem. Many of our
descriptions are new, and all our results are all consistent with known results
in physics. We also conjecture a physical framework for normalizable B-fields
and show consistency with mathematics.
  We dedicate this paper to Herb Clemens, in admiration for his myriad
fundamental contributions to complex algebraic geometry, together with his more
recent interest in F-theory in physics. This paper deals with three of Herb's
interests: Hodge theory, topology of algebraic varieties, and F-theory, and so
is a fitting way for us to express our appreciation for his contributions over
a period of more than five decades.


title: Higher-rank Brill-Noether loci on nodal reducible curves

abstract:
  In this paper we deal with Brill-Noether theory for higher-rank sheaves on a
polarized nodal reducible curve $(C,\underline{w})$ following the ideas of
[arXiv:alg-geom/9511003v1]. We study the Brill-Noether loci of
$\underline{w}$-stable depth one sheaves on $C$ having rank $r$ on all
irreducible components and having small slope. In analogy with what happens in
the smooth case, we prove that these loci are closely related to BGN
extensions. Moreover, we produce irreducible components of the expected
dimension for these Brill-Noether loci.


title: Transitivity on subclasses of bipartite graphs

abstract:
  Let $G=(V, E)$ be a graph where $V$ and $E$ are the vertex and edge set,
respectively. For two disjoint subsets $A$ and $B$, we say $A$ dominates $B$ if
every vertex of $B$ is adjacent to at least one vertex of $A$. A vertex
partition $\pi = \{V_1, V_2, \ldots, V_k\}$ of $G$ is called a \emph{transitive
$k$-partition} if $V_i$ dominates $V_j$ for all $i,j$ where $1\leq i<j\leq k$.
The maximum integer $k$ for which the above partition exists is called
\emph{transitivity} of $G$ and it is denoted by $Tr(G)$. The \textsc{Maximum
Transitivity Problem} is to find a transitive partition of a given graph with
the maximum number of partitions. It was known that the decision version of
\textsc{Maximum Transitivity Problem} is NP-complete for general graphs, which
was proved by Hedetniemi et al. [Iterated colorings of graphs, \emph{Discrete
Mathematics}, 278, 2004]. This paper first strengthens the NP-completeness
result by showing that this problem remains NP-complete for perfect elimination
bipartite graphs. On the other hand, we propose a linear-time algorithm for
finding the transitivity of a given bipartite chain graph. We then characterize
graphs with transitivity at least $t$ for any integer $t$. This result answers
two open questions posed by J. T. Hedetniemi and S. T. Hedetniemi [The
transitivity of a graph, \emph{J. Combin. Math. Combin. Comput}, 104, 2018].


title: What is in #P and what is not?

abstract:
  For several classical nonnegative integer functions, we investigate if they
are members of the counting complexity class #P or not. We prove #P membership
in surprising cases, and in other cases we prove non-membership, relying on
standard complexity assumptions or on oracle separations.
  We initiate the study of the polynomial closure properties of #P on affine
varieties, i.e., if all problem instances satisfy algebraic constraints. This
is directly linked to classical combinatorial proofs of algebraic identities
and inequalities. We investigate #TFNP and obtain oracle separations that prove
the strict inclusion of #P in all standard syntactic subclasses of #TFNP-1.


title: Impulse response estimation via flexible local projections

abstract:
  This paper introduces a flexible local projection that generalizes the model
by Jord\'a (2005) to a non-parametric setting using Bayesian Additive
Regression Trees. Monte Carlo experiments show that our BART-LP model is able
to capture non-linearities in the impulse responses. Our first application
shows that the fiscal multiplier is stronger in recession than in expansion
only in response to contractionary fiscal shocks, but not in response to
expansionary fiscal shocks. We then show that financial shocks generate effects
on the economy that increase more than proportionately in the size of the shock
when the shock is negative, but not when the shock is positive.


title: Polynomial Time Algorithm for ARRIVAL on Tree-like Multigraphs

abstract:
  A rotor walk in a directed graph can be thought of as a deterministic version
of a Markov Chain, where a pebble moves from vertex to vertex following a
simple rule until a terminal vertex, or sink, is reached. The ARRIVAL problem,
as defined by Dohrau and al., consists in determining which sink will be
reached. While the walk itself can take an exponential number of steps, this
problem belongs to the complexity class NP$\cap$co-NP without being known to be
in P. Several variants have been studied where we add one or two players to the
model, defining deterministic analogs of stochastic models (e.g., Markovian
decision processes, Stochastic Games) with rotor-routing rules instead of
random transitions. The corresponding decision problem address the existence of
strategies for players that ensure some condition on the reached sink. These
problems are known to be $NP$-complete for one player and $PSPACE$-complete for
two players. In this work, we define a class of directed graphs, namely
tree-like multigraphs, which are multigraphs having the global shape of an
undirected tree. We prove that the different variants of the reachability
problem with zero, one, or two players can be solved in linear time, while the
number of steps of rotor walks can still be exponential. To achieve this, we
define a notion of return flow, which counts the number of times the pebble
will bounce back in subtrees of the graph.


title: Magnetic molecule tunnel heterojunctions

abstract:
  We characterize molecular magnet heterojunctions in which sublimated CoPc
films as thin as 5 nm are sandwiched between transparent conducting
bottom-layer indium tin oxide and top-layer soft-landing eutectic GaIn (EGaIn)
electrodes. The roughness of the cobalt phthalocyanine (CoPc) films was
determined by atomic force microscopy to be on the order of several nanometers,
and crystalline ordering of lying-down planar molecules was confirmed by X-ray
diffraction. The current-voltage (I-V) characteristics reveal the onset of a
superconducting gap at Tc = 6 K, which together with higher temperature fits to
a modified Simmons' model, provide incontrovertible evidence for direct quantum
mechanical tunneling processes through the magnetic molecules in our
heterojunctions. The voltage dependent features in the differential conductance
measurements relate to spin states of single molecules or aggregates of
molecules and should prove to be important for quantum information device
development.


title: SSR-GNNs: Stroke-based Sketch Representation with Graph Neural Networks

abstract:
  This paper follows cognitive studies to investigate a graph representation
for sketches, where the information of strokes, i.e., parts of a sketch, are
encoded on vertices and information of inter-stroke on edges. The resultant
graph representation facilitates the training of a Graph Neural Networks for
classification tasks, and achieves accuracy and robustness comparable to the
state-of-the-art against translation and rotation attacks, as well as stronger
attacks on graph vertices and topologies, i.e., modifications and addition of
strokes, all without resorting to adversarial training. Prior studies on
sketches, e.g., graph transformers, encode control points of stroke on
vertices, which are not invariant to spatial transformations. In contrary, we
encode vertices and edges using pairwise distances among control points to
achieve invariance. Compared with existing generative sketch model for one-shot
classification, our method does not rely on run-time statistical inference.
Lastly, the proposed representation enables generation of novel sketches that
are structurally similar to while separable from the existing dataset.


title: Attention Mechanism in Neural Networks: Where it Comes and Where it Goes

abstract:
  A long time ago in the machine learning literature, the idea of incorporating
a mechanism inspired by the human visual system into neural networks was
introduced. This idea is named the attention mechanism, and it has gone through
a long development period. Today, many works have been devoted to this idea in
a variety of tasks. Remarkable performance has recently been demonstrated. The
goal of this paper is to provide an overview from the early work on searching
for ways to implement attention idea with neural networks until the recent
trends. This review emphasizes the important milestones during this progress
regarding different tasks. By this way, this study aims to provide a road map
for researchers to explore the current development and get inspired for novel
approaches beyond the attention.


title:
A Soft-Bodied Aerial Robot for Collision Resilience and Contact-Reactive
  Perching

abstract:
  Compared to their biological counterparts, aerial robots demonstrate limited
capabilities when tasked to interact in unstructured environments. Very often,
the limitation lies in their inability to tolerate collisions and to
successfully land, or perch, on objects of unknown shape. Over the past years,
efforts to address this have introduced designs that incorporate mechanical
impact protection and grasping/perching structures at the cost of reduced
agility and flight time due to added weight and bulkiness. In this work, we
develop a fabric-based, soft-bodied aerial robot (SoBAR) composed of both
contact-reactive perching and embodied impact protection structures while
remaining lightweight and streamlined. The robot is capable to 1) pneumatically
vary its body stiffness for collision resilience and 2) utilize a hybrid
fabric-based, bistable (HFB) grasper to perform passive grasping. When compared
to conventional rigid drone frames the SoBAR successfully demonstrates its
ability to dissipate impact from head-on collisions and maintain flight
stability without any structural damage. Furthermore, in dynamic perching
scenarios the HFB grasper is capable to convert impact energy upon contact into
firm grasp through rapid body shape conforming in less than 4ms. We
exhaustively study and offer insights for this novel perching scheme through
grasping characterization, grasp wrench analysis, and experimental grasping
validations in objects with various shapes. Finally, we demonstrate the
complete control pipeline for SoBAR to approach an object, dynamically perch on
it, recover from it, and land.


title:
On the Relationship Between Explanations, Fairness Perceptions, and
  Decisions

abstract:
  It is known that recommendations of AI-based systems can be incorrect or
unfair. Hence, it is often proposed that a human be the final decision-maker.
Prior work has argued that explanations are an essential pathway to help human
decision-makers enhance decision quality and mitigate bias, i.e., facilitate
human-AI complementarity. For these benefits to materialize, explanations
should enable humans to appropriately rely on AI recommendations and override
the algorithmic recommendation when necessary to increase distributive fairness
of decisions. The literature, however, does not provide conclusive empirical
evidence as to whether explanations enable such complementarity in practice. In
this work, we (a) provide a conceptual framework to articulate the
relationships between explanations, fairness perceptions, reliance, and
distributive fairness, (b) apply it to understand (seemingly) contradictory
research findings at the intersection of explanations and fairness, and (c)
derive cohesive implications for the formulation of research questions and the
design of experiments.


title:
Compatibility of Neutrino DIS Data and Its Impact on Nuclear Parton
  Distribution Functions

abstract:
  In global analyses of nuclear parton distribution functions (nPDFs), neutrino
deep-inelastic scattering (DIS) data have been argued to exhibit tensions with
the data from charged-lepton DIS. Using the nCTEQ framework, we investigate
these possible tensions both internally and with the data sets used in our
recent nPDF analysis nCTEQ15WZSIH. We take into account nuclear effects in the
calculation of the deuteron structure function $F_2^D$ using the CJ15 analysis.
The resulting nPDF fit, nCTEQ15WZSIHdeut, serves as the basis for our
comparison with inclusive neutrino DIS and charm dimuon production data. Using
$\chi^2$ hypothesis testing, we confirm evidence of tensions with these data
and study the impact of the proton PDF baseline as well as the treatment of
data correlation and normalization uncertainties. We identify the experimental
data and kinematic regions that generate the tensions and present several
possible approaches how a consistent global analysis with neutrino data can be
performed. We show that the tension can be relieved using a kinematic cut at
low $x$ ($x>0.1$) and also investigate a possibility of managing the tensions
by using uncorrelated systematic errors. Finally, we present a different
approach identifying a subset of neutrino data which leads to a consistent
global analysis without any additional cuts. Understanding these tensions
between the neutrino and charged-lepton DIS data is important not only for a
better flavor separation in global analyses of nuclear and proton PDFs, but
also for neutrino physics and for searches for physics beyond the Standard
Model.


title: Person Re-Identification

abstract:
  Person Re-Identification (Re-ID) is an important problem in computer
vision-based surveillance applications, in which one aims to identify a person
across different surveillance photographs taken from different cameras having
varying orientations and field of views. Due to the increasing demand for
intelligent video surveillance, Re-ID has gained significant interest in the
computer vision community. In this work, we experiment on some existing Re-ID
methods that obtain state of the art performance in some open benchmarks. We
qualitatively and quantitaively analyse their performance on a provided
dataset, and then propose methods to improve the results. This work was the
report submitted for COL780 final project at IIT Delhi.


title:
Anharmonic thermodynamic properties and phase boundary across the
  post-perovskite transition in MgSiO$_3$

abstract:
  To address the effects of lattice anharmonicity across the perovskite to
post-perovskite transition in MgSiO$_3$, we conduct calculations using the
phonon quasiparticle (PHQ) approach. The PHQ is based on \textit{ab initio}
molecular dynamics and, in principle, captures full anharmonicity. Free
energies in the thermodynamic limit ($N \rightarrow \infty$) are computed using
temperature-dependent quasiparticle dispersions within the phonon gas model.
Systematic results on anharmonic thermodynamic properties and phase boundary
are reported. Both the local density approximation (LDA) and the generalized
gradient approximation (GGA) calculations are performed to provide confident
constraints on these properties. Anharmonic effects are demonstrated by
comparing results with those obtained using the quasiharmonic approximation
(QHA). The inadequacy of the QHA is indicated by its overestimation of thermal
expansivity and thermodynamic Gr\"{u}neisen parameter and its converged
isochoric heat capacity in the high-temperature limit. The PHQ phase boundary
has a Clapeyron slope ($dP/dT$) that increases with temperature. This result
contrasts with the nearly zero curvature of the QHA phase boundary.
Anharmonicity bends the phase boundary to lower temperatures at high pressures.
Implications for the double-crossing of the phase boundary by the mantle
geotherm are discussed.


title: AutoLossGen: Automatic Loss Function Generation for Recommender Systems

abstract:
  In recommendation systems, the choice of loss function is critical since a
good loss may significantly improve the model performance. However, manually
designing a good loss is a big challenge due to the complexity of the problem.
A large fraction of previous work focuses on handcrafted loss functions, which
needs significant expertise and human effort. In this paper, inspired by the
recent development of automated machine learning, we propose an automatic loss
function generation framework, AutoLossGen, which is able to generate loss
functions directly constructed from basic mathematical operators without prior
knowledge on loss structure. More specifically, we develop a controller model
driven by reinforcement learning to generate loss functions, and develop
iterative and alternating optimization schedule to update the parameters of
both the controller model and the recommender model. One challenge for
automatic loss generation in recommender systems is the extreme sparsity of
recommendation datasets, which leads to the sparse reward problem for loss
generation and search. To solve the problem, we further develop a reward
filtering mechanism for efficient and effective loss generation. Experimental
results show that our framework manages to create tailored loss functions for
different recommendation models and datasets, and the generated loss gives
better recommendation performance than commonly used baseline losses. Besides,
most of the generated losses are transferable, i.e., the loss generated based
on one model and dataset also works well for another model or dataset. Source
code of the work is available at https://github.com/rutgerswiselab/AutoLossGen.


title: Canonical analysis for Chern-Simons modification of general relativity

abstract:
  By using the Gitman-Lyakhovich-Tyutin canonical analysis for higher-order
theories a four-dimensional Chern-Simons modification of general relativity is
analyzed. The counting of physical degrees of freedom, the symmetries, and the
fundamental Dirac brackets are reported. Moreover, we report the complete
structure of the constraints and its Dirac algebra is developed.


title:
Discrete Event Simulation to Evaluate Shelter Capacity Expansion Options
  for LGBTQ+ Homeless Youth

abstract:
  The New York City (NYC) youth shelter system is instrumental in providing
housing, counseling, and other support services to runaway and homeless youth
and young adults (RHY). There are various types of programs provided through
these shelters: drop-in services, crisis-emergency housing, transitional
independent living, and long-term housing services. These resources reduce the
vulnerability of RHY to human trafficking, yet most shelters do not have
sufficient funding to fulfill the entirety of their needs. This paper presents
a Discrete Event Simulation model of a crisis-emergency and drop-in center for
LGBTQ+ youth in NYC, which helps to analyze capacity shortages in the current
system. The model uses a combination of secondary data collected from publicly
available resources and primary data obtained in interviews with service
providers and key stakeholder such as NYC Coalition for Homeless Youth.
Potential capacity expansion interventions for crisis-emergency beds and case
management are evaluated.


title: Roots of Polynomials and Umbilics of Surfaces

abstract:
  For certain polynomials we relate the number of roots inside the unit circle
of with the index of a non-degenerate isolated umbilic point on a real analytic
surface in Euclidean 3-space.
  In particular, for $N>0$ we prove that for a certain ($N+2$)-real dimensional
family of complex polynomials of degree $N$, the number of roots inside the
unit circle is less than or equal to $1+N/2$. This bound is established as
follows.
  From the polynomial we construct a convex real analytic surface containing an
isolated umbilic point, such that the index of the umbilic point is determined
by the number of roots of the polynomial that lie inside the unit circle. The
bound on the number of roots then follows from Hamburger's bound on the index
of an isolated umbilic point on a convex real analytic surface.


title:
Quantifying and reducing spin contamination in algebraic diagrammatic
  construction theory of charged excitations

abstract:
  Algebraic diagrammatic construction (ADC) theory is a computationally
efficient and accurate approach for simulating electronic excitations in
chemical systems. However, for the simulations of excited states in molecules
with unpaired electrons the performance of ADC methods can be affected by the
spin contamination in unrestricted Hartree-Fock (UHF) reference wavefunctions.
In this work, we benchmark the accuracy of ADC methods for electron attachment
and ionization of open-shell molecules with the UHF reference orbitals
(EA/IP-ADC/UHF) and develop an approach to quantify the spin contamination in
the charged excited states. Following this assessment, we demonstrate that the
spin contamination can be reduced by combining EA/IP-ADC with the reference
orbitals from restricted open-shell Hartree-Fock (ROHF) or orbital-optimized
M{\o}ller-Plesset perturbation (OMP) theories. Our numerical results
demonstrate that for open-shell systems with strong spin contamination in the
UHF reference the third-order EA/IP-ADC methods with the ROHF or OMP reference
orbitals are similar in accuracy to equation-of-motion coupled cluster theory
with single and double excitations.


title:
Light in the Larynx: a Miniaturized Robotic Optical Fiber for In-office
  Laser Surgery of the Vocal Folds

abstract:
  This letter reports the design, construction, and experimental validation of
a novel hand-held robot for in-office laser surgery of the vocal folds.
In-office endoscopic laser surgery is an emerging trend in Laryngology: It
promises to deliver the same patient outcomes of traditional surgical treatment
(i.e., in the operating room), at a fraction of the cost. Unfortunately, office
procedures can be challenging to perform; the optical fibers used for laser
delivery can only emit light forward in a line-of-sight fashion, which severely
limits anatomical access. The robot we present in this letter aims to overcome
these challenges. The end effector of the robot is a steerable laser fiber,
created through the combination of a thin optical fiber (0.225 mm) with a
tendon-actuated Nickel-Titanium notched sheath that provides bending. This
device can be seamlessly used with most commercially available endoscopes, as
it is sufficiently small (1.1 mm) to pass through a working channel. To control
the fiber, we propose a compact actuation unit that can be mounted on top of
the endoscope handle, so that, during a procedure, the operating physician can
operate both the endoscope and the steerable fiber with a single hand. We
report simulation and phantom experiments demonstrating that the proposed
device substantially enhances surgical access compared to current clinical
fibers.


title:
R-MBO: A Multi-surrogate Approach for Preference Incorporation in
  Multi-objective Bayesian Optimisation

abstract:
  Many real-world multi-objective optimisation problems rely on computationally
expensive function evaluations. Multi-objective Bayesian optimisation (BO) can
be used to alleviate the computation time to find an approximated set of Pareto
optimal solutions. In many real-world problems, a decision-maker has some
preferences on the objective functions. One approach to incorporate the
preferences in multi-objective BO is to use a scalarising function and build a
single surrogate model (mono-surrogate approach) on it. This approach has two
major limitations. Firstly, the fitness landscape of the scalarising function
and the objective functions may not be similar. Secondly, the approach assumes
that the scalarising function distribution is Gaussian, and thus a closed-form
expression of an acquisition function e.g., expected improvement can be used.
We overcome these limitations by building independent surrogate models
(multi-surrogate approach) on each objective function and show that the
distribution of the scalarising function is not Gaussian. We approximate the
distribution using Generalised value distribution. We present an a-priori
multi-surrogate approach to incorporate the desirable objective function values
(or reference point) as the preferences of a decision-maker in multi-objective
BO. The results and comparison with the existing mono-surrogate approach on
benchmark and real-world optimisation problems show the potential of the
proposed approach.


title: "The Goose" Pulsar Wind Nebula of PSR J1016-5857: The Birth of a Plerion

abstract:
  We report the results of X-ray (CXO) and radio (ATCA) observations of the
pulsar wind nebula (PWN) powered by the young pulsar PSR J1016--5857, which we
dub "the Goose" PWN. In both bands the images reveal a tail-like PWN morphology
which can be attributed to pulsar's motion. By comparing archival and new CXO
observations, we measure the pulsar's proper motion $\mu=28.8\pm7.3$ mas/yr,
yielding a projected pulsar velocity $v \approx 440\pm110$ km/s (at d=3.2 kpc);
its direction is consistent with the PWN shape. Radio emission from the PWN is
polarized, with the magnetic field oriented along the pulsar tail. The radio
tail connects to a larger radio structure (not seen in X-rays) which we
interpret as a relic PWN (also known as a plerion). The spectral analysis of
the CXO data shows that the PWN spectrum softens from $\Gamma=1.7$ to
$\Gamma\approx2.3-2.5$ with increasing distance from the pulsar. The softening
can be attributed to rapid synchrotron burn-off, which would explain the lack
of X-ray emission from the older relic PWN. In addition to non-thermal PWN
emission, we detected thermal emission from a hot plasma which we attribute to
the host SNR. The radio PWN morphology and the proper motion of the pulsar
suggest that the reverse shock passed through the pulsar's vicinity and pushed
the PWN to one side.


title: Learning Storm Surge with Gradient Boosting

abstract:
  Storm surge is a major natural hazard for coastal regions, responsible both
for significant property damage and loss of life. Accurate, efficient models of
storm surge are needed both to assess long-term risk and to guide emergency
management decisions. While high-fidelity ocean circulation models such as the
ADvanced CIRCulation (ADCIRC) model can accurately predict storm surge, they
are very computationally expensive. Consequently, there have been a number of
efforts in recent years to develop data-driven surrogate models for storm
surge. While these models can attain good accuracy and are highly efficient,
they are often limited to a small geographical region and a fixed set of output
locations.
  We develop a novel surrogate model for peak storm surge prediction based on
gradient boosting. Unlike most surrogate approaches, our model is not
explicitly constrained to a fixed set of output locations or specific
geographical region. The model is trained with a database of 446 synthetic
storms that make landfall on the Texas coast and obtains a mean absolute error
of 0.25 meters. We additionally present a test of the model on Hurricanes Ike
(2008) and Harvey (2017).


title: FedShuffle: Recipes for Better Use of Local Work in Federated Learning

abstract:
  The practice of applying several local updates before aggregation across
clients has been empirically shown to be a successful approach to overcoming
the communication bottleneck in Federated Learning (FL). In this work, we
propose a general recipe, FedShuffle, that better utilizes the local updates in
FL, especially in the heterogeneous regime. Unlike many prior works, FedShuffle
does not assume any uniformity in the number of updates per device. Our
FedShuffle recipe comprises four simple-yet-powerful ingredients: 1) local
shuffling of the data, 2) adjustment of the local learning rates, 3) update
weighting, and 4) momentum variance reduction (Cutkosky and Orabona, 2019). We
present a comprehensive theoretical analysis of FedShuffle and show that both
theoretically and empirically, our approach does not suffer from the objective
function mismatch that is present in FL methods which assume homogeneous
updates in heterogeneous FL setups, e.g., FedAvg (McMahan et al., 2017). In
addition, by combining the ingredients above, FedShuffle improves upon FedNova
(Wang et al., 2020), which was previously proposed to solve this mismatch. We
also show that FedShuffle with momentum variance reduction can improve upon
non-local methods under a Hessian similarity assumption. Finally, through
experiments on synthetic and real-world datasets, we illustrate how each of the
four ingredients used in FedShuffle helps improve the use of local updates in
FL.


title:
Minimizing Client Drift in Federated Learning via Adaptive Bias
  Estimation

abstract:
  In Federated Learning a number of clients collaborate to train a model
without sharing their data. Client models are optimized locally and are
communicated through a central hub called server. A major challenge is to deal
with heterogeneity among clients' data which causes the local optimization to
drift away with respect to the global objective. In order to estimate and
therefore remove this drift, variance reduction techniques have been
incorporated into Federated Learning optimization recently. However, the
existing solutions propagate the error of their estimations, throughout the
optimization trajectory which leads to inaccurate approximations of the
clients' drift and ultimately failure to remove them properly. In this paper,
we address this issue by introducing an adaptive algorithm that efficiently
reduces clients' drift. Compared to the previous works on adapting variance
reduction to Federated Learning, our approach uses less or the same level of
communication bandwidth, computation or memory. Additionally, it addresses the
instability problem--prevalent in prior work, caused by increasing norm of the
estimates which makes our approach a much more practical solution for large
scale Federated Learning settings. Our experimental results demonstrate that
the proposed algorithm converges significantly faster and achieves higher
accuracy compared to the baselines in an extensive set of Federated Learning
benchmarks.


title: Phase transition of eigenvalues in deformed Ginibre ensembles

abstract:
  Consider a random matrix of size $N$ as an additive deformation of the
complex Ginibre ensemble under a deterministic matrix $X_0$ with a finite rank,
independent of $N$. When some eigenvalues of $X_0$ separate from the unit disk,
outlier eigenvalues may appear asymptotically in the same locations, and their
fluctuations exhibit surprising phenomena that highly depend on the Jordan
canonical form of $X_0$. These findings are largely due to Benaych-Georges and
Rochet \cite{BR}, Bordenave and Capitaine \cite{BC16}, and Tao \cite{Ta13}.
When all eigenvalues of $X_0$ lie inside the unit disk, we prove that local
eigenvalue statistics at the spectral edge form a new class of determinantal
point processes, for which correlation kernels are characterized in terms of
the repeated erfc integrals. This thus completes a non-Hermitian analogue of
the BBP phase transition in Random Matrix Theory. Similar results hold for the
deformed quaternion Ginibre ensemble.


title:
An Adversarial Attack Analysis on Malicious Advertisement URL Detection
  Framework

abstract:
  Malicious advertisement URLs pose a security risk since they are the source
of cyber-attacks, and the need to address this issue is growing in both
industry and academia. Generally, the attacker delivers an attack vector to the
user by means of an email, an advertisement link or any other means of
communication and directs them to a malicious website to steal sensitive
information and to defraud them. Existing malicious URL detection techniques
are limited and to handle unseen features as well as generalize to test data.
In this study, we extract a novel set of lexical and web-scrapped features and
employ machine learning technique to set up system for fraudulent advertisement
URLs detection. The combination set of six different kinds of features
precisely overcome the obfuscation in fraudulent URL classification. Based on
different statistical properties, we use twelve different formatted datasets
for detection, prediction and classification task. We extend our prediction
analysis for mismatched and unlabelled datasets. For this framework, we analyze
the performance of four machine learning techniques: Random Forest, Gradient
Boost, XGBoost and AdaBoost in the detection part. With our proposed method, we
can achieve a false negative rate as low as 0.0037 while maintaining high
accuracy of 99.63%. Moreover, we devise a novel unsupervised technique for data
clustering using K- Means algorithm for the visual analysis. This paper
analyses the vulnerability of decision tree-based models using the limited
knowledge attack scenario. We considered the exploratory attack and implemented
Zeroth Order Optimization adversarial attack on the detection models.


title: Wafer-scale nanofabrication of telecom single-photon emitters in silicon

abstract:
  A highly promising route to scale millions of qubits is to use quantum
photonic integrated circuits (PICs), where deterministic photon sources,
reconfigurable optical elements, and single-photon detectors are monolithically
integrated on the same silicon chip. The isolation of single-photon emitters,
such as the G centers and W centers, in the optical telecommunication O-band,
has recently been realized in silicon. In all previous cases, however,
single-photon emitters were created uncontrollably in random locations,
preventing their scalability. Here, we report the controllable fabrication of
single G and W centers in silicon wafers using focused ion beams (FIB) with a
probability exceeding 50%. We also implement a scalable, broad-beam
implantation protocol compatible with the
complementary-metal-oxide-semiconductor (CMOS) technology to fabricate single
telecom emitters at desired positions on the nanoscale. Our findings unlock a
clear and easily exploitable pathway for industrial-scale photonic quantum
processors with technology nodes below 100 nm.


title: FIMP Dark Matter in Heterotic M-Theory

abstract:
  Within the context of $N=1$ supersymmetric heterotic $M$-theory, we present a
"freeze-in" mechanism for producing dark matter via a "moduli portal" between
the observable and hidden sectors. It is assumed that the observable sector
consists of the MSSM or some physically acceptable extension of it, while the
hidden sector is chosen so as to satisfy all physical and mathematical
constraints. Dark matter production processes are examined for two fundamental
types of hidden sectors; those whose gauge bundle structure group contains an
anomalous $U(1)$ and those whose structure group is non-Abelian and anomaly
free. The couplings of the dilaton and the "universal" modulus to all fields of
the observable and hidden sectors are presented and analyzed. These
interactions are then combined to produce a moduli portal from a thermal bath
of observable sector particles to the hidden sector. These processes are then
analyzed for both the anomalous and non-anomalous cases. It is shown that only
the uncharged hidden sector matter scalars can play the role of dark matter,
and that these are predominantly produced during the "reheating" epoch on the
observable sector. Within the context of both an anomalous and non-anomalous
hidden sector, we calculated the dark matter "relic density". We show that in
both case, for a wide choice of moduli vacua, one can correctly predict the
observabled relic density. For the anomalous $U(1)$ case, we choose a specific
physically acceptable vacuum within the context of the $B-L$ MSSM and show that
one precisely obtains the measured dark matter relic abundance.


title: Wireless at the Nanoscale: Towards Magnetically Tunable Beam Steering

abstract:
  Plasmonic wireless nanolinks hold great promise to overcome limitations from
conventional metallic wires, namely narrow bandwidths, Ohmic losses, dispersion
and cross-talking. However, current developments are limited to the wireless
communication between two fixed points, i.e., a fixed transmitter with a fixed
receiver, which in turn limits the energy efficiency and integration levels. In
this work, we propose the use of magnetic fields for active tuning of the
radiation beam steering of plasmonic nanoantennas. The physical principle
behind our concept is shown with rigorous solution of the radiation pattern of
a radiating dipolar source in the presence of magnetic fields. The results
indicate that the proposed scheme is feasible with plasmonic nanoantennas made
of ferromagnetic or noble metals in the presence of an applied magnetic field.


title: Divisible Codes for Quantum Computation

abstract:
  Divisible codes are defined by the property that codeword weights share a
common divisor greater than one. They are used to design signals for
communications and sensing, and this paper explores how they can be used to
protect quantum information as it is transformed by logical gates. Given a CSS
code $\mathcal{C}$, we derive conditions that are both necessary and sufficient
for a transversal diagonal physical operator $U_Z$ to preserve $\mathcal{C}$
and induce $U_L$. The group of $Z$-stabilizers in a CSS code $\mathcal{C}$ is
determined by the dual of a classical $[n, k_1]$ binary code $\mathcal{C}_1$,
and the group of $X$-stabilizers is determined by a classical $[n, k_2]$ binary
code $\mathcal{C}_2$ that is contained in $\mathcal{C}_1$. The requirement that
a diagonal physical operator $U_Z$ fixes a CSS code $\mathcal{C}$ leads to
constraints on the congruence of weights in cosets of $\mathcal{C}_2$. These
constraints are a perfect fit to divisible codes, and represent an opportunity
to take advantage of the extensive literature on classical codes with two or
three weights. We construct new families of CSS codes using cosets of the first
order Reed Muller code defined by quadratic forms. We provide a simple
alternative to the standard method of deriving the coset weight distributions
(based on Dickson normal form) that may be of independent interest. Finally, we
develop an approach to circumventing the Eastin-Knill Theorem which states that
no QECC can implement a universal set of logical gates through transversal
gates alone. The essential idea is to design stabilizer codes in layers, with
$N_1$ inner qubits and $N_2$ outer qubits, and to assemble a universal set of
fault tolerant gates on the inner qubits.


title: Link Budget Analysis for Free-Space Optical Satellite Networks

abstract:
  Free-space optical satellite networks (FSOSNs) will employ free-space optical
links between satellites and between satellites and ground stations, and the
link budget for optical inter-satellite links and optical uplink/downlink is
analyzed in this paper. The satellites in these FSOSNs will have limited energy
and thereby limited power, and we investigate the effect of link distance and
link margin on optical inter-satellite link transmission power, and the effect
of slant distance, elevation angle, and link margin on optical uplink/downlink
transmission power. We model these optical links and compute the results for
various parameters. We observe that the transmission power increases when the
link distance increases for inter-satellite and uplink/downlink communications,
while the transmission power decreases when the elevation angle increases for
uplink/downlink transmission. We also observe an inverse relationship between
link margin and link distance. Furthermore, we highlight some practical
insights and design guidelines gained from this analysis.


title:
Subarcsecond imaging of a solar active region filament with ALMA and
  IRIS

abstract:
  Quiescent filaments appear as absorption features on the solar disk when
observed in chromospheric lines and at continuum wavelengths in the millimeter
(mm) range. Active region (AR) filaments are their small-scale, low-altitude
analogues, but they could not be resolved in previous mm observations. This
spectral diagnostic can provide insight into the details of the formation and
physical properties of their fine threads, which are still not fully
understood. Here, we shed light on the thermal structure of an AR filament
using high-resolution brightness temperature ($T_{\rm b}$) maps taken with ALMA
Band 6 complemented by simultaneous IRIS near-UV spectra, Hinode/SOT
photospheric magnetograms, and SDO/AIA extreme-UV images. Some of the dark
threads visible in the AIA 304 {\AA} passband and in the core of Mg II
resonance lines have dark ($T_{\rm b}<5000$K) counterparts in the 1.25 mm maps,
but their visibility significantly varies across the filament spine and in
time. These opacity changes are possibly related to variations in temperature
and electron density in filament fine structures. The coolest $T_{\rm b}$
values ($<$5000 K) coincide with regions of low integrated intensity in the Mg
II h and k lines. ALMA Band 3 maps taken after the Band 6 ones do not clearly
show the filament structure, contrary to the expectation that the contrast
should increase at longer wavelengths based on previous observations of
quiescent filaments. The ALMA maps are not consistent with isothermal
conditions, but the temporal evolution of the filament may partly account for
this.


title:
On consistency of Bayesian parameter estimations for a certain class of
  Markov models (discrete case)

abstract:
  J.L. Doob's method of establishing consistency of an estimator of a parameter
under minimal assumptions is extended to a certain class of ergodic Markov
chains.


title:
Reduced-order modeling for Koopman operators of nonautonomous dynamic
  systems in multiscale media

abstract:
  In this article, we present reduced-order modeling for Koopman operators of
nonautonomous dynamic systems in multiscale media. Koopman operators can
transform the nonlinear dynamic systems into linear systems through acting on
observation function spaces. Different from the case of autonomous dynamic
systems, the Koopman operator family of nonautonomous dynamic systems
significantly depend on a time pair. In order to effectively estimate the
time-dependent Koopman operators, a moving time window is used to decompose the
snapshot data, and the extended dynamic mode decomposition method is applied to
computing the Koopman operators in each local temporal domain. To accurately
construct the models of dynamic systems in multiscale media, we may use high
spatial dimension of observation data. It is challenging to compute the Koopman
operators using the high dimensional data. Thus, the strategy of reduced-order
modeling is proposed to treat the difficulty. The proposed reduced-order
modeling includes two stages: offline stage and online stage. In offline stage,
a block-wise low rank decomposition is used to reduce the spatial dimension of
initial snapshot data. For the nonautonomous dynamic systems, real-time
observation data may be required to update the Koopman operators. An online
reduced-order modeling is proposed to correct the offline reduced-order
modeling.Three methods are developed for the online reduced-order modeling:
fully online, semi-online and adaptive online. The adaptive online method
automatically selects the fully online or semi-online and can achieve a good
trade-off between modeling accuracy and efficiency. A few numerical examples
are presented to illustrate the performance of the different reduced-order
modeling methods.