title:
Strain-induced Landau Levels in arbitrary dimensions with an exact
  spectrum

abstract:
  Certain non-uniform strain applied to graphene flakes has been shown to
induce pseudo-Landau levels in the single-particle spectrum, which can be
rationalized in terms of a pseudo-magnetic field for electrons near the Dirac
points. However, this Landau level structure is in general approximate and
restricted to low energies. Here we introduce a family of strained bipartite
tight-binding models in arbitrary spatial dimension d and analytically prove
that their entire spectrum consists of perfectly degenerate pseudo-Landau
levels. This construction generalizes the case of triaxial strain on graphene's
honeycomb lattice to arbitrary d; in d=3 our model corresponds to tetraxial
strain on the diamond lattice. We discuss general aspects of pseudo-Landau
levels in arbitrary d.

categories: cond-mat.mes-hall cond-mat.stat-mech math-ph math.MP


title:
The intermediate neutron-capture process and carbon-enhanced metal-poor
  stars

abstract:
  Carbon-enhanced metal-poor (CEMP) stars in the Galactic Halo display
enrichments in heavy elements associated with either the s (slow) or the r
(rapid) neutron-capture process (e.g., barium and europium respectively), and
in some cases they display evidence of both. The abundance patterns of these
CEMP-s/r stars, which show both Ba and Eu enrichment, are particularly puzzling
since the s and the r processes require neutron densities that are more than
ten orders of magnitude apart, and hence are thought to occur in very different
stellar sites with very different physical conditions. We investigate whether
the abundance patterns of CEMP-s/r stars can arise from the nucleosynthesis of
the intermediate neutron-capture process (the i process), which is
characterised by neutron densities between those of the s and the r processes.
Using nuclear network calculations, we study neutron capture nucleosynthesis at
different constant neutron densities n ranging from $10^7$ to $10^{15}$
cm$^{-3}$. With respect to the classical s process resulting from neutron
densities on the lowest side of this range, neutron densities on the highest
side result in abundance patterns that show an increased production of heavy
s-process and r-process elements but similar abundances of the light s-process
elements. Such high values of n may occur in the thermal pulses of asymptotic
giant branch (AGB) stars due to proton ingestion episodes. Comparison to the
surface abundances of 20 CEMP-s/r stars show that our modelled i-process
abundances successfully reproduce observed abundance patterns that could not be
previously explained by s-process nucleosynthesis. Because the i-process models
fit the abundances of CEMP-s/r stars so well, we propose that this class should
be renamed as CEMP-i.


title:
Spin Ice Thin Film: Surface Ordering, Partial Magnetic Wetting and
  Emergent Square Ice

abstract:
  Motivated by recent realizations of Dy$_{2}$Ti$_{2}$O$_{7}$ and
Ho$_{2}$Ti$_{2}$O$_{7}$ spin ice thin films, and more generally by the physics
of confined gauge fields, we study a model of spin ice thin film with surfaces
perpendicular to the $[001]$ cubic axis. The resulting open boundaries make
half of the bonds on the interfaces inequivalent. By tuning the strength of
these inequivalent "orphan" bonds, dipolar interactions induce a surface
ordering equivalent to a two-dimensional crystallization of magnetic surface
charges. This surface ordering can also be expected on the surfaces of bulk
crystals. In analogy with partial wetting in soft matter, spins just below the
surface are more correlated than in the bulk, but \emph{not} ordered. For
ultrathin films made of one cubic unit cell, once the surfaces are ordered, a
square ice phase is stabilized over a finite temperature window, as confirmed
by its entropy and the presence of pinch points in the structure factor.
Ultimately, the square ice degeneracy is lifted at lower temperature and the
system orders in analogy with the well-known $F$-transition of the $6$-vertex
model.


title:
Merger of a White Dwarf-Neutron Star Binary to $10^{29}$ Carat Diamonds:
  Origin of the Pulsar Planets

abstract:
  We show that the merger and tidal disruption of a C/O white dwarf (WD) by a
neutron star (NS) binary companion provides a natural formation scenario for
the PSR B1257+12 planetary system. Starting with initial conditions for the
debris disk produced of the disrupted WD, we model its long term viscous
evolution, including for the first time the effects of mass and angular
momentum loss during the early radiatively inefficient accretion flow (RIAF)
phase and accounting for the unusual C/O composition on the disk opacity. For
plausible values of the disk viscosity $\alpha \sim 10^{-3}-10^{-2}$ and the
RIAF mass loss efficiency, we find that the disk mass remaining near the planet
formation radius at the time of solid condensation is sufficient to explain the
pulsar planets. Rapid rocky planet formation via gravitational instability of
the solid carbon-dominated disk is facilitated by the suppression of vertical
shear instabilities due to the high solid-to-gas ratio. Additional evidence
supporting a WD-NS merger scenario includes (1) the low observed occurrence
rate of pulsar planets ($\lesssim 1\%$ of NS birth), comparable to the expected
WD-NS merger rate; (2) accretion by the NS during the RIAF phase is sufficient
to spin PSR B1257+12 up to its observed 6 ms period; (3) similar models of `low
angular momentum' disks, such as those produced from supernova fallback, find
insufficient mass reaching the planet formation radius. The unusually high
space velocity of PSR B1257+12 of $\gtrsim 326\,{\rm km\,s}^{-1}$ suggests a
possible connection to the Calcium-rich transients, dim supernovae which occur
in the outskirts of their host galaxies and were proposed to result from
mergers of WD-NS binaries receiving SN kicks. The C/O disk composition implied
by our model likely results in carbon-rich planets with diamond interiors.


title:
Echoes of ECOs: gravitational-wave signatures of exotic compact objects
  and of quantum corrections at the horizon scale

abstract:
  Gravitational waves from binary coalescences provide one of the cleanest
signatures of the nature of compact objects. It has been recently argued that
the post-merger ringdown waveform of exotic ultracompact objects is initially
identical to that of a black-hole, and that putative corrections at the horizon
scale will appear as secondary pulses after the main burst of radiation. Here
we extend this analysis in three important directions: (i) we show that this
result applies to a large class of exotic compact objects with a photon sphere
for generic orbits in the test-particle limit; (ii) we investigate the
late-time ringdown in more detail, showing that it is universally characterized
by a modulated and distorted train of "echoes" of the modes of vibration
associated with the photon sphere; (iii) we study for the first time
equal-mass, head-on collisions of two ultracompact boson stars and compare
their gravitational-wave signal to that produced by a pair of black-holes. If
the initial objects are compact enough as to mimic a binary black-hole
collision up to the merger, the final object exceeds the maximum mass for boson
stars and collapses to a black-hole. This suggests that - in some
configurations - the coalescence of compact boson stars might be almost
indistinguishable from that of black-holes. On the other hand, generic
configurations display peculiar signatures that can be searched for in
gravitational-wave data as smoking guns of exotic compact objects.


title:
A detection of the integrated Sachs-Wolfe imprint of cosmic
  superstructures using a matched-filter approach

abstract:
  We present a new method for detection of the integrated Sachs-Wolfe (ISW)
imprints of cosmic superstructures on the cosmic microwave background, based on
a matched filtering approach. The expected signal-to-noise ratio for this
method is comparable to that obtained from the full cross-correlation, and
unlike other stacked filtering techniques it is not subject to an a posteriori
bias. We apply this method to Planck CMB data using voids and superclusters
identified in the CMASS galaxy data from the Sloan Digital Sky Survey Data
Release 12, and measure the ISW amplitude to be $A_\mathrm{ISW}=1.64\pm0.53$
relative to the $\Lambda$CDM expectation, corresponding to a $3.1\sigma$
detection. In contrast to some previous measurements of the ISW effect of
superstructures, our result is in agreement with the $\Lambda$CDM model.


title:
The impact of stellar feedback on the density and velocity structure of
  the interstellar medium

abstract:
  We study the impact of stellar feedback in shaping the density and velocity
structure of neutral hydrogen (HI) in disc galaxies. For our analysis, we carry
out $\sim 4.6$pc resolution $N$-body+adaptive mesh refinement (AMR)
hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way
(MW), and a Large and Small Magellanic Cloud (LMC, SMC). We quantify the
density and velocity structure of the interstellar medium using power spectra
and compare the simulated galaxies to observed HI in local spiral galaxies from
THINGS (The HI Nearby Galaxy Survey). Our models with stellar feedback give an
excellent match to the observed THINGS HI density power spectra. We find that
kinetic energy power spectra in feedback regulated galaxies, regardless of
galaxy mass and size, show scalings in excellent agreement with super-sonic
turbulence ($E(k)\propto k^{-2}$) on scales below the thickness of the HI
layer. We show that feedback influences the gas density field, and drives gas
turbulence, up to large (kpc) scales. This is in stark contrast to density
fields generated by large scale gravity-only driven turbulence. We conclude
that the neutral gas content of galaxies carries signatures of stellar feedback
on all scales.


title:
Search for sharp and smooth spectral signatures of $\mu\nu$SSM gravitino
  dark matter with Fermi-LAT

abstract:
  The $\mu\nu$SSM solves the $\mu$ problem of supersymmetric models and
reproduces neutrino data, simply using couplings with right-handed neutrinos
$\nu$'s. Given that these couplings break explicitly $R$ parity, the gravitino
is a natural candidate for decaying dark matter in the $\mu \nu$SSM. In this
work we carry out a complete analysis of the detection of $\mu \nu$SSM
gravitino dark matter through $\gamma$-ray observations. In addition to the
two-body decay producing a sharp line, we include in the analysis the
three-body decays producing a smooth spectral signature. We perform first a
deep exploration of the low-energy parameter space of the $\mu \nu$SSM taking
into account that neutrino data must be reproduced. Then, we compare the
$\gamma$-ray fluxes predicted by the model with Fermi-LAT observations. In
particular, with the 95$\%$ CL upper limits on the total diffuse extragalactic
$\gamma$-ray background using 50 months of data, together with the upper limits
on line emission from an updated analysis using 69.9 months of data. For
standard values of bino and wino masses, gravitinos with masses larger than
about 4 GeV, or lifetimes smaller than $10^{28}$ s, produce too large fluxes
and are excluded as dark matter candidates. However, when limiting scenarios
with large and close values of the gaugino masses are considered, the
constraints turn out to be less stringent, excluding masses larger than 17 GeV
and lifetimes smaller than $4\times 10^{25}$ s.


title:
Ground State thermodynamic and response properties of electron gas in a
  strong magnetic and electric field: Exact analytical solutions for a
  conventional semiconductor and for Graphene

abstract:
  Consequences of an exceedingly strong electric field (E field) on the ground
state energetics and transport properties of a 2D spinless electron gas in a
perpendicular magnetic field (a Quantum Hall Effect (QHE) configuration) are
investigated to all orders in the fields. For a conventional semiconductor, we
find fractional values of the Hall conductivity and some magnetoelectric
coefficients for certain values of E and B fields that do not result from
interactions or impurities, but are a pure consequence of a strong enough
in-plane E field. We also determine analytically the ground state energy, and
response properties such as magnetization and polarization as functions of the
electromagnetic field in the strong E field limit. In the case of Graphene, we
obtain more complex behaviors leading to the possibility of irrational Hall
values. The results are also qualitatively discussed in connection to various
mechanisms for the QHE-breakdown.


title: Resolving the planet-hosting inner regions of the LkCa 15 disk

abstract:
  LkCa 15 hosts a pre-transitional disk as well as at least one accreting
protoplanet orbiting in its gap. Previous disk observations have focused mainly
on the outer disk, which is cleared inward of ~50 au. The planet candidates, on
the other hand, reside at orbital radii around 15 au, where disk observations
have been unreliable until recently. Here we present new J-band imaging
polarimetry of LkCa 15 with SPHERE IRDIS, yielding the most accurate and
detailed scattered-light images of the disk to date down to the planet-hosting
inner regions. We find what appear to be persistent asymmetric structures in
the scattering material at the location of the planet candidates, which could
be responsible at least for parts of the signals measured with sparse-aperture
masking. These images further allow us to trace the gap edge in scattered light
at all position angles and search the inner and outer disks for morphological
substructure. The outer disk appears smooth with slight azimuthal variations in
polarized surface brightness, which may be due to shadowing from the inner disk
or a two-peaked polarized phase function. We find that the near-side gap edge
revealed by polarimetry matches the sharp crescent seen in previous ADI imaging
very well. Finally, the ratio of polarized disk to stellar flux is more than
six times larger in J-band than in the RI bands.


title: On the Composition of Young, Directly Imaged Giant Planets

abstract:
  The past decade has seen significant progress on the direct detection and
characterization of young, self-luminous giant planets at wide orbital
separations from their host stars. Some of these planets show evidence for
disequilibrium processes like transport-induced quenching in their atmospheres;
photochemistry may also be important, despite the large orbital distances.
These disequilibrium chemical processes can alter the expected composition,
spectral behavior, thermal structure, and cooling history of the planets, and
can potentially confuse determinations of bulk elemental ratios, which provide
important insights into planet-formation mechanisms. Using a
thermo/photochemical kinetics and transport model, we investigate the extent to
which disequilibrium chemistry affects the composition and spectra of directly
imaged giant exoplanets. Results for specific "young Jupiters" such as HR 8799
b and 51 Eri b are presented, as are general trends as a function of planetary
effective temperature, surface gravity, incident ultraviolet flux, and strength
of deep atmospheric convection. We find that quenching is very important on
young Jupiters, leading to CO/CH4 and N2/NH3 ratios much greater than, and H2O
mixing ratios a factor of a few less than, chemical-equilibrium predictions.
Photochemistry can also be important on such planets, with CO2 and HCN being
key photochemical products. Carbon dioxide becomes a major constituent when
stratospheric temperatures are low and recycling of water via the H2 + OH
reaction becomes kinetically stifled. Young Jupiters with effective
temperatures <~ 700 K are in a particularly interesting photochemical regime
that differs from both transiting hot Jupiters and our own solar-system giant
planets.


title:
Spatial Multiplexing of QPSK Signals with a Single Radio: Antenna Design
  and Over-the-Air Experiments

abstract:
  The paper describes the implementation and performance analysis of the first
fully-operational beam-space MIMO antenna for the spatial multiplexing of two
QPSK streams. The antenna is composed of a planar three-port radiator with two
varactor diodes terminating the passive ports. Pattern reconfiguration is used
to encode the MIMO information onto orthogonal virtual basis patterns in the
far-field. A measurement campaign was conducted to compare the performance of
the beam-space MIMO system with a conventional 2-by-?2 MIMO system under
realistic propagation conditions. Propagation measurements were conducted for
both systems and the mutual information and symbol error rates were estimated
from Monte-Carlo simulations over the measured channel matrices. The results
show the beam-space MIMO system and the conventional MIMO system exhibit
similar finite-constellation capacity and error performance in NLOS scenarios
when there is sufficient scattering in the channel. In comparison, in LOS
channels, the capacity performance is observed to depend on the relative
polarization of the receiving antennas.


title: A Model of Controlled Growth

abstract:
  We consider a free boundary problem for a system of PDEs, modeling the growth
of a biological tissue. A morphogen, controlling volume growth, is produced by
specific cells and then diffused and absorbed throughout the domain. The
geometric shape of the growing tissue is determined by the instantaneous
minimization of an elastic deformation energy, subject to a constraint on the
volumetric growth. For an initial domain with $C^{2,\alpha}$ boundary, our main
result establishes the local existence and uniqueness of a classical solution,
up to a rigid motion.


title:
LiRa: A New Likelihood-Based Similarity Score for Collaborative
  Filtering

abstract:
  Recommender system data presents unique challenges to the data mining,
machine learning, and algorithms communities. The high missing data rate, in
combination with the large scale and high dimensionality that is typical of
recommender systems data, requires new tools and methods for efficient data
analysis. Here, we address the challenge of evaluating similarity between two
users in a recommender system, where for each user only a small set of ratings
is available. We present a new similarity score, that we call LiRa, based on a
statistical model of user similarity, for large-scale, discrete valued data
with many missing values. We show that this score, based on a ratio of
likelihoods, is more effective at identifying similar users than traditional
similarity scores in user-based collaborative filtering, such as the Pearson
correlation coefficient. We argue that our approach has significant potential
to improve both accuracy and scalability in collaborative filtering.


title: Modeling Chebyshev's Bias in the Gaussian Primes as a Random Walk

abstract:
  One aspect of Chebyshev's bias is the phenomenon that a prime number, $ q $,
modulo another prime number, $ p$, experimentally seems to be slightly more
likely to be a nonquadratic residue than a quadratic residue. We thought it
would be interesting to model this residue bias as a "random" walk using
Legendre symbol values as steps. Such a model would allow us to easily
visualize the bias. In addition, we would be able to extend our model to other
number fields.
  In this report, we first outline underlying theory and some motivations for
our research. In the second section, we present our findings in the rational
prime numbers. We found evidence that Chebyshev's bias, if modeled as a
Legendre symbol $ \left(\frac{q}{p}\right)$ walk, may be somewhat reduced by
only allowing $ q$ to iterate over primes with nonquadratic residue (mod $ 4$).
In the final section, we extend our Legendre symbol walks to the Gaussian
primes and present our main findings. Let $ \pi_1 = \alpha+\beta i$ and $ \pi_2
= \beta+\alpha i$. We observed strong ($ \pm$) correlations between Gaussian
Legendre symbol walks for $ \left[\frac{a+bi}{\pi_1}\right]$ and $
\left[\frac{a+bi}{\pi_2}\right]$ where $ N(\pi_1) = N(\pi_2)$ and $ a+bi$
iterates over Gaussian primes in the first quadrant. We attempt an explanation
of why, for some norms, the plots for $ \pi_1$ and $ \pi_2$ have strong
positive correlation, while, for other norms, the plots have strong negative
correlation. We hope to have written in a way that makes our observations
accessible to readers without prior formal training in number theory.


title:
Using parallelism techniques to improve sequential and multi-core
  sorting performance

abstract:
  We propose new sequential sorting operations by adapting techniques and
methods used for designing parallel sorting algorithms. Although the norm is to
parallelize a sequential algorithm to improve performance, we adapt a
contrarian approach: we employ parallel computing techniques to speed up
sequential sorting. Our methods can also work for multi-core sorting with minor
adjustments that do not necessarily require full parallelization of the
original sequential algorithm. The proposed approach leads to the development
of asymptotically efficient deterministic and randomized sorting operations
whose practical sequential and multi-core performance, as witnessed by an
experimental study, matches or surpasses existing optimized sorting algorithm
implementations.
  We utilize parallel sorting techniques such as deterministic regular sampling
and random oversampling. We extend the notion of deterministic regular sampling
into deterministic regular oversampling for sequential and multi-core sorting
and demonstrate its potential. We then show how these techniques can be used
for sequential sorting and also lead to better multi-core sorting algorithm
performance as witnessed by the undertaken experimental study.


title: Exponential bases on triangular domains

abstract:
  We construct explicit exponential bases on triangles in R^2 and on infinite
unions of segments on the real line.


title:
r-process Production Sites as inferred from Eu Abundances in Dwarf
  Galaxies

abstract:
  Recent observations of $r$-process material in ultra-faint dwarf galaxies
(UFDs) shed light on the sources of these elements. Strong upper limits on the
Eu mass in some UFDs combined with detections of much larger masses in a UFD,
Reticulum II, and other dwarf galaxies imply that Eu production is dominated by
rare events, and that the minimal Eu mass observed in any UFD is approximately
the amount of Eu mass produced per event. This is consistent with other
independent observations in the Galaxy. We estimate, using a model independent
likelihood analysis, the rate and Eu (Fe) mass produced per $r$-process (Fe
production) event in dwarf galaxies including classical dwarfs and UFDs. The
mass and rate of the Fe production events are consistent with the normal
core-collapse supernova~(ccSN) scenario. The Eu mass per event is $3\times
10^{-5}M_{\odot}<\tilde{m}_{\rm Eu}<2\times 10^{-4}M_{\odot}$, corresponding to
a total $r$-process mass per event of $6\times
10^{-3}M_{\odot}<\tilde{m}_{r-process}<4\times 10^{-2}M_{\odot}$. The rate of
$r$-process events is $2.5\times 10^{-4}<R_{rp/SN}<1.4\times 10^{-3}$ as
compared with the ccSNe rate. These values are consistent with the total Eu
mass observed in our own Galaxy, suggesting that the same mechanism is behind
the production of $r$-process events in both dwarf galaxies and the Milky Way,
and that it may be the dominant mechanism for production of $r$-process
elements in the Universe. The results are consistent with neutron star mergers
estimates, but cannot rule out other rare core collapse scenarios, provided
that they produce a significant amounts of $r$-process material per event.


title:
The complex dynamics of memristive circuits: analytical results and
  universal slow relaxation

abstract:
  Networks with memristive elements (resistors with memory) are being explored
for a variety of applications ranging from unconventional computing to models
of the brain. However, analytical results that highlight the role of the graph
connectivity on the memory dynamics are still a few, thus limiting our
understanding of these important dynamical systems. In this paper, we derive an
exact matrix equation of motion that takes into account all the network
constraints of a purely memristive circuit, and we employ it to derive
analytical results regarding its relaxation properties. We are able to describe
the memory evolution in terms of orthogonal projection operators onto the
subspace of fundamental loop space of the underlying circuit. This orthogonal
projection explicitly reveals the coupling between the spatial and temporal
sectors of the memristive circuits and compactly describes the circuit
topology. For the case of disordered graphs, we are able to explain the
emergence of a power law relaxation as a superposition of exponential
relaxation times with a broad range of scales using random matrices. This power
law is also {\it universal}, namely independent of the topology of the
underlying graph but dependent only on the density of loops. In the case of
circuits subject to alternating voltage instead, we are able to obtain an
approximate solution of the dynamics, which is tested against a specific
network topology. These result suggest a much richer dynamics of memristive
networks than previously considered.


title: Dirac operator with linear potential and its perturbations

abstract:
  We prove that canonical Dirac expression with linear potential generates
operators on axis and half axis, for which we can find the eigenvalues and
eigenfunctions in explicit form. We construct the perturbations of these
operators with in advance given spectra.


title: Design and Demonstration of Ultra Wide Bandgap AlGaN Tunnel Junctions

abstract:
  Ultra violet light emitting diodes (UV LEDs) face critical limitations in
both the injection efficiency and light extraction efficiency due to the
resistive and absorbing p-type contact layers. In this work, we investigate the
design and application of polarization engineered tunnel junctions for
ultra-wide bandgap AlGaN (Al mole fraction higher than 50%) materials towards
highly efficient UV LEDs. We demonstrate that polarization-induced 3D charge is
beneficial in reducing tunneling barriers especially for high composition AlGaN
tunnel junctions. The design of graded tunnel junction structures could lead to
low tunneling resistance below 10-3 Ohm cm2 and low voltage consumption below 1
V (at 1 kA/cm2) for high composition AlGaN tunnel junctions. Experimental
demonstration of 292 nm emission was achieved through non-equilibrium hole
injection into wide bandgap materials with bandgap energy larger than 4.7 eV,
and detailed modeling of tunnel junctions shows that they can be engineered to
have low resistance, and can enable efficient emitters in the UV-C wavelength
range.


title: 4-dimensional analogues of Dehn's lemma

abstract:
  We investigate certain $4$-dimensional analogues of the classical
$3$-dimensional Dehn's lemma, giving examples where such analogues do or do not
hold, in the smooth and topological categories. In particular, we show that an
essential $2$-sphere $S$ in the boundary of a simply connected $4$-manifold $W$
such that $S$ is null-homotopic in $W$ need not extend to an embedding of a
ball in $W$. However, if $W$ is simply connected (or more generally a
$4$-manifold with abelian fundamental group) with boundary a homology sphere,
then $S$ bounds a topologically embedded ball in $W$. Moreover, we give
examples where such an $S$ does not bound any smoothly embedded ball in $W$. In
a similar vein, we construct incompressible tori $T\subseteq \partial W$ where
$W$ is a contractible $4$-manifold such that $T$ extends to a map of a solid
torus in $W$, but not to any embedding of a solid torus in $W$. Moreover, we
construct an incompressible torus $T$ in the boundary of a contractible
$4$-manifold $W$ such that $T$ extends to a topological embedding of a solid
torus in $W$ but no smooth embedding. As an application of our results about
tori, we address a question posed by Gompf about extending certain families of
diffeomorphisms of $3$-manifolds which he has recently used to construct
infinite corks.


title:
Quantum statistics of classical particles derived from the condition of
  free diffusion coefficient

abstract:
  We derive an equation for the current of particles in energy space; particles
are subject to a mean field effective potential that may represent quantum
effects. From the assumption that non-interacting particles imply a free
diffusion coefficient in energy space we derive Maxwell-Boltzmann, Fermi-Dirac
and Bose-Einstein statistics. Other new statistics are associated to a free
diffusion coefficient; their thermodynamic properties are analyzed using the
grand partition function. A negative relation between pressure and energy
density for low temperatures can be derived, suggesting a possible connection
with cosmological dark energy models.


title:
Breakdown of the Equivalence between Gravitational Mass and Energy for a
  Quantum Body: Theory and Suggested Experiments

abstract:
  We review recent theoretical results, obtained for the equivalence between
gravitational mass and energy of a composite quantum body as well as for its
breakdown at macroscopic and microscopic levels. In particular, we discuss that
the expectation values of passive and active gravitational masses operators are
equivalent to the expectation value of energy for electron stationary quantum
states in a hydrogen atom. On the other hand, for superpositions of the
stationary quantum states, inequivalence between the gravitational masses and
energy appears at a macroscopic level. It reveals itself as time-dependent
oscillations of the expectation values of passive and active gravitational
masses, which can be, in principle, experimentally measured. Inequivalence
between passive gravitational mass and energy at a microscopic level can be
experimentally observed as unusual electromagnetic radiation, emitted by a
macroscopic ensemble of the atoms. We propose the corresponding experiment,
which can be done on the Earth's orbit, using small spacecraft. If such
experiment is done it would be the first direct observation of quantum effects
in general relativity.


title: Exponential Stability and the Markus-Yamabe Conjecture in Compact Spaces

abstract:
  In this note we show that if a continuous-time, nonlinear, time-invariant,
finite-dimensional system evolves on a compact subset of Rn and if the Jacobian
of the vector field is Hurwitz at each point of the compact set, then there is
a unique equilibrium on the set and solutions exponentially converge to it.
This shows that the Markus-Yamabe conjecture, which is false in general on Rn,
n>2, holds on compact sets. The results of this note can be viewed as an
application of Krasovskii's method for constructing Lyapunov functions and we
are able to similarly construct Lyapunov-like functions valid on the given
compact set. Examples are provided to illustrate the result.


title: Devito: automated fast finite difference computation

abstract:
  Domain specific languages have successfully been used in a variety of fields
to cleanly express scientific problems as well as to simplify implementation
and performance opti- mization on different computer architectures. Although a
large number of stencil languages are available, finite differ- ence domain
specific languages have proved challenging to design because most practical use
cases require additional features that fall outside the finite difference
abstraction. Inspired by the complexity of real-world seismic imaging problems,
we introduce Devito, a domain specific language in which high level equations
are expressed using symbolic expressions from the SymPy package. Complex
equations are automatically manipulated, optimized, and translated into highly
optimized C code that aims to perform compa- rably or better than hand-tuned
code. All this is transpar- ent to users, who only see concise symbolic
mathematical expressions.


title:
Joint Estimation of Multiple Dependent Gaussian Graphical Models with
  Applications to Mouse Genomics

abstract:
  Gaussian graphical models are widely used to represent conditional dependence
among random variables. In this paper, we propose a novel estimator for data
arising from a group of Gaussian graphical models that are themselves
dependent. A motivating example is that of modeling gene expression collected
on multiple tissues from the same individual: here the multivariate outcome is
affected by dependencies acting not only at the level of the specific tissues,
but also at the level of the whole body; existing methods that assume
independence among graphs are not applicable in this case. To estimate multiple
dependent graphs, we decompose the problem into two graphical layers: the
systemic layer, which affects all outcomes and thereby induces cross- graph
dependence, and the category-specific layer, which represents graph-specific
variation. We propose a graphical EM technique that estimates both layers
jointly, establish estimation consistency and selection sparsistency of the
proposed estimator, and confirm by simulation that the EM method is superior to
a simple one-step method. We apply our technique to mouse genomics data and
obtain biologically plausible results.


title: Tunable QoS-Aware Network Survivability

abstract:
  Coping with network failures has been recognized as an issue of major
importance in terms of social security, stability and prosperity. It has become
clear that current networking standards fall short of coping with the complex
challenge of surviving failures. The need to address this challenge has become
a focal point of networking research. In particular, the concept of
\textbf{\emph{tunable survivability}} offers major performance improvements
over traditional approaches. Indeed, while the traditional approach aims at
providing full (100\%) protection against network failures through disjoint
paths, it was realized that this requirement is too restrictive in practice.
Tunable survivability provides a quantitative measure for specifying the
desired level (0\%-100\%) of survivability and offers flexibility in the choice
of the routing paths. Previous work focused on the simpler class of
"bottleneck" criteria, such as bandwidth. In this study, we focus on the
important and much more complex class of \emph{additive} criteria, such as
delay and cost. First, we establish some (in part, counter-intuitive)
properties of the optimal solution. Then, we establish efficient algorithmic
schemes for optimizing the level of survivability under additive end-to-end QoS
bounds. Subsequently, through extensive simulations, we show that, at the price
of \emph{negligible} reduction in the level of survivability, a major
improvement (up to a factor of $2$) is obtained in terms of end-to-end QoS
performance. Finally, we exploit the above findings in the context of a network
design problem, in which, for a given investment budget, we aim to improve the
survivability of the network links.


title: Z-dark search with the ATLAS detector

abstract:
  The search of the "hidden sector" via new neutral light bosons Z-dark
($Z_{d}$) could be revealed by the study of the decay of the discovered
Higgs-like boson or any other undiscovered Higgs boson. After the LHC concluded
a successful first period of running, the ATLAS Collaboration published its
latest results on the $H\rightarrow Z_{d}Z_{d}\rightarrow 4l$ analysis using up
to 20 fb$^{-1}$ of integrated luminosity at $\sqrt{s}=8$ TeV. In this
proceeding I present a summary of the recent results on the search of the
$Z_{d}$ in the signature $H\rightarrow Z_{d}Z_{d}\rightarrow 4l$ with the ATLAS
detector at the LHC.


title: Hanani-Tutte for Radial Planarity II

abstract:
  A drawing of a graph $G$ is radial if the vertices of $G$ are placed on
concentric circles $C_1, \ldots, C_k$ with common center $c$, and edges are
drawn radially: every edge intersects every circle centered at $c$ at most
once. $G$ is radial planar if it has a radial embedding, that is, a
crossing-free radial drawing. If the vertices of $G$ are ordered or partitioned
into ordered levels (as they are for leveled graphs), we require that the
assignment of vertices to circles corresponds to the given ordering or
leveling. A pair of edges $e$ and $f$ in a graph is independent if $e$ and $f$
do not share a vertex.
  We show that a graph $G$ is radial planar if $G$ has a radial drawing in
which every two independent edges cross an even number of times; the radial
embedding has the same leveling as the radial drawing. In other words, we
establish the strong Hanani-Tutte theorem for radial planarity. This
characterization yields a very simple algorithm for radial planarity testing.


title: Lopsided Approximation of Amoebas

abstract:
  The amoeba of a Laurent polynomial is the image of the corresponding
hypersurface under the coordinatewise log absolute value map. In this article,
we demonstrate that a theoretical amoeba approximation method due to Purbhoo
can be used efficiently in practice. To do this, we resolve the main bottleneck
in Purbhoo's method by exploiting relations between cyclic resultants. We use
the same approach to give an approximation of the Log preimage of the amoeba of
a Laurent polynomial using semi-algebraic sets. We also provide a SINGULAR/SAGE
implementation of these algorithms, which shows a significant speedup when our
specialized cyclic resultant computation is used, versus a general purpose
resultant algorithm.


title: Artificial circumzenithal and circumhorizontal arcs

abstract:
  We revisit a water glass experiment often used to demonstrate a rainbow. On a
closer look, it also turns out to be a rather close analogy of a different kind
of atmospheric optics phenomenon altogether: The geometry may be used to
faithfully reproduce the circumzenithal and the circumhorizontal halos,
providing a missing practical demonstration experiment for those beautiful and
common natural ice halo displays.


title:
A-posteriori snapshot location for POD in optimal control of linear
  parabolic equations

abstract:
  In this paper we study the approximation of an optimal control problem for
linear para\-bolic PDEs with model order reduction based on Proper Orthogonal
Decomposition (POD-MOR). POD-MOR is a Galerkin approach where the basis
functions are obtained upon information contained in time snapshots of the
parabolic PDE related to given input data. In the present work we show that for
POD-MOR in optimal control of parabolic equations it is important to have
knowledge about the controlled system at the right time instances. We propose
to determine the time instances (snapshot locations) by an a-posteriori error
control concept. This method is based on a reformulation of the optimality
system of the underlying optimal control problem as a second order in time and
fourth order in space elliptic system which is approximated by a space-time
finite element method. Finally, we present numerical tests to illustrate our
approach and to show the effectiveness of the method in comparison to existing
approaches.


title:
Online state and parameter estimation in Dynamic Generalised Linear
  Models

abstract:
  Inference for streaming time-series is tightly coupled with the problem of
Bayesian on-line state and parameter inference. In this paper we will introduce
Dynamic Generalised Linear Models, the class of models often chosen to model
continuous and discrete time-series data. We will look at three different
approaches which allow on-line estimation and analyse the results when applied
to different real world datasets related to inference for streaming data.
Sufficient statistics based methods delay known problems, such as particle
impoverishment, especially when applied to long running time-series, while
providing reasonable parameter estimations when compared to exact methods, such
as Particle Marginal Metropolis-Hastings. State and observation forecasts will
also be analysed as a performance metric. By benchmarking against a "gold
standard" (off-line) method, we can better understand the performance of
on-line methods in challenging real-world scenarios.


title: On geometric quantization of $b$-symplectic manifolds

abstract:
  We study a notion of pre-quantization for $b$-symplectic manifolds. We use it
to construct a formal geometric quantization of $b$-symplectic manifolds
equipped with Hamiltonian torus actions with nonzero modular weight. We show
that these quantizations are finite dimensional $T$-modules.


title: Beam steering and impedance matching of plasmonic horn nanoantennas

abstract:
  In this paper, we study a plasmonic horn nanoantenna on a metal-backed
substrate. The horn nanoantenna structure consists of a two-wire transmission
line (TWTL) flared at the end. We analyze the effect of the substrate thickness
on the nanoantenna's radiation pattern, and demonstrate beam steering in a
broad range of elevation angles. Furthermore, we analyze the effect of the
ground plane on the impedance matching between the antenna and the TWTL, and
observe that the ground plane increases the back reflection into the waveguide.
To reduce the reflection, we develop a transmission line model to design an
impedance matching section which leads to 99.75% power transmission to the
nanoantenna.


title: Harmonic self-maps of cohomogeneity one manifolds

abstract:
  We develop the theory of equivariant harmonic self-maps of compact
cohomogeneity one manifolds and construct new harmonic self-maps of the compact
Lie groups SO(4L+2), L >= 1, with degree -3, of SO(8), SO(14) and SO(26) with
degree -5 each, of SO(10) with degree -7, and of SO(14) with degree -11 by
exhibiting linear solutions to non-linear singular boundary value problems.


title: Compactness of Hankel operators with continuous symbols

abstract:
  Let $\Omega$ be a bounded convex Reinhardt domain in $\mathbb{C}^2$ and
$\phi\in C(\bar{\Omega})$. We show that the Hankel operator $H_{\phi}$ is
compact if and only if $\phi$ is holomorphic along every non-trivial analytic
disc in the boundary of $\Omega$.


title: An inequality for expectation of means of positive random variables

abstract:
  Suppose that $X,Y$ are positive random variable and $m$ a numerical
(commutative) mean. We prove that the inequality ${\rm E} (m(X,Y)) \leq m({\rm
E} (X), {\rm E} (Y))$ holds if and only if the mean is generated by a concave
function. With due changes we also prove that the same inequality holds for all
operator means in the Kubo-Ando setting. The case of the harmonic mean was
proved by C.R. Rao and B.L.S. Prakasa Rao.


title: Points of order 13 on elliptic curves

abstract:
  We pick up the study of 13-torsion in elliptic curves where Mazur and Tate
left off 45 years ago. We consider various questions concerning elliptic curves
defined over the maximal totally real subfield of the 13th cyclotomic field
(where J_1(13) acquires everywhere good reduction), and over quadratic
extensions.


title: How the green light was given for gravitational wave search

abstract:
  The recent detection of gravitational waves by the LIGO/VIRGO team is an
incredibly impressive achievement of experimental physics. It is also a
tremendous success of the theory of General Relativity. It confirms the
existence of black holes; shows that binary black holes exist; that they may
collide and that during the merging process gravitational waves are produced.
These are all predictions of General Relativity theory in its fully nonlinear
regime. The existence of gravitational waves was predicted by Albert Einstein
in 1916 within the framework of linearized Einstein theory. Contrary to common
belief, even the very \emph{definition} of a gravitational wave in the fully
nonlinear Einstein theory was provided only after Einstein's death. Actually,
Einstein had arguments against the existence of nonlinear gravitational waves
(they were erroneous but he did not accept this), which virtually stopped
development of the subject until the mid 1950s. This is what we refer to as the
\emph{Red Light} for gravitational waves research. In the following years, the
theme was picked up again and studied vigorously by various experts, mainly
Herman Bondi, Felix Pirani, Ivor Robinson and Andrzej Trautman, where the
theoretical obstacles concerning gravitational wave existence were successfully
overcome, thus giving the `Green Light' for experimentalists to start designing
detectors, culminating in the recent LIGO/VIRGO discovery. In this note we tell
the story of this theoretical breakthrough. Particular attention is given to
the fundamental 1958 papers of Trautman, which seem to be lesser known outside
the circle of General Relativity experts. A more detailed technical description
of these 2 papers is given in the Appendix.

categories: physics.hist-ph astro-ph.CO gr-qc hep-ph hep-th


title:
Excited collective states of nuclei within Bohr Hamiltonian with
  Tietz-Hua potential

abstract:
  In this paper, we present new analytical solutions of the Bohr Hamiltonian
problem that we derived with the Tietz-Hua potential, here used for describing
the {\beta}-part of the nuclear collective potential plus harmonic oscillator
one for the {\gamma}-part. Also, we proceed to a systematic comparison of the
numerical results obtained with this kind of {\beta}-potential with others
which are widely used in such a framework as well as with the experiment. The
calculations are carried out for energy spectra and electromagnetic transition
probabilities for {\gamma}-unstable and axially symmetric deformed nuclei. In
the same frame, we show the effect of the shape flatness of the
{\beta}-potential beyond its minimum on transition rates calculations.


title: The Several Dimensional Gambler's Ruin Problem

abstract:
  We consider the simple random walk on the $N$-dimensional integer lattice
from the perspective of evaluating asymptotically the duration of play in the
multidimensional gambler\apost s ruin problem. We show that, under suitable
rescalings, all $p$-moments of exit-times from balls in the $L$-infinity
metric, and all $p$-moments of partial-maxima values in this metric, possess
associated asymptotic limit expressions, admitting two representations each. We
derive for this purpose multidimensional refinements of the corresponding
two-folded extension of Erd\H os-Kac theorem, which we revisit to this end. We
show in particular a simplifying proof approach, which relies on an application
of the optional stopping theorem, and yields the corresponding first-passage
times asymptotics in parallel. We observe a direct manner of proof of the
relation among the two limit expressions by Brownian motion scaling. We
indicate in a manner intended to be brief and comprehensive other known proof
approaches for the purposes of comparison and completeness.


title:
Neutrino masses in the $SU(4)_L \otimes U(1)_X$ electroweak extension of
  the standard model

abstract:
  We study the neutrino mass generation in the $SU(4)_L \otimes U(1)_X$
electroweak extension of the standard model by considering non-renormalizable
dimension five effective operators. It is shown that there exist two topologies
for the realizations of such an operator at the tree-level and for one of the
three-family models is explore the neutrino phenomenology after extending its
particle content with an $SU(4)_L$ fermion singlet and a scalar decuplet.
Constraints in the available parameters space of the model are partially
discussed.


title:
Connecting low- and high-mass star formation: the intermediate-mass
  protostar IRAS 05373+2349 VLA 2

abstract:
  Until recently, there have been few studies of the protostellar evolution of
intermediate-mass (IM) stars, which may bridge the low- and high-mass regimes.
This paper aims to investigate whether the properties of an IM protostar within
the IRAS 05373+2349 embedded cluster are similar to that of low- and/or
high-mass protostars. We carried out Very Large Array as well as Combined Array
for Research in Millimeter Astronomy continuum and 12CO(J=1-0) observations,
which uncover seven radio continuum sources (VLA 1-7). The spectral index of
VLA 2, associated with the IM protostar is consistent with an ionised stellar
wind or jet. The source VLA 3 is coincident with previously observed H2
emission line objects aligned in the north-south direction (P.A. -20 to -12
deg), which may be either an ionised jet emanating from VLA 2 or
(shock-)ionised cavity walls in the large-scale outflow from VLA 2. The
position angle between VLA 2 and 3 is slightly misaligned with the large-scale
outflow we map at ~5-arcsec resolution in 12CO (P.A. ~30 deg), which in the
case of a jet suggests precession. The emission from the mm core associated
with VLA 2 is also detected; we estimate its mass to be 12-23 Msun, depending
on the contribution from ionised gas. Furthermore, the large-scale outflow has
properties intermediate between outflows from low- and high-mass young stars.
Therefore, we conclude that the IM protostar within IRAS 05373+2349 is
phenomenologically as well as quantitatively intermediate between the low- and
high-mass domains.


title: Sparse Recovery With Integrality Constraints

abstract:
  We investigate conditions for the unique recoverability of sparse
integer-valued signals from a small number of linear measurements. Both the
objective of minimizing the number of nonzero components, the so-called
$\ell_0$-norm, as well as its popular substitute, the $\ell_1$-norm, are
covered. Furthermore, integrality constraints and possible bounds on the
variables are investigated. Our results show that the additional prior
knowledge of signal integrality allows for recovering more signals than what
can be guaranteed by the established recovery conditions from (continuous)
compressed sensing. Moreover, even though the considered problems are \NP-hard
in general (even with an $\ell_1$-objective), we investigate testing the
$\ell_0$-recovery conditions via some numerical experiments. It turns out that
the corresponding problems are quite hard to solve in practice using black-box
software. However, medium-sized instances of $\ell_0$- and
$\ell_1$-minimization with binary variables can be solved exactly within
reasonable time.


title:
Roughly Polynomial Time: A Concept of Tractability Covering All Known
  Natural NP-complete Problems

abstract:
  We introduce a concept of efficiency for which we can prove that it applies
to all paddable languages, but still does not conflict with potential worst
case intractability. Note that the family of paddable languages apparently
includes all known natural NP-complete problems. We call our concept Roughly
Polynomial Time (RoughP). A language $L,$ over an at least 2-symbol alphabet,
is in RoughP, if the following hold: (1) there exists a bijective encoding
$\alpha$ of strings, such that both $\alpha$ and its inverse are computable in
polynomial time; (2) there is a polynomial time algorithm $\cal A$, which is an
errorless heuristic for $L,$ with exponentially vanishing failure rate relative
to the $\alpha$-spheres $S^{(\alpha)}_n=\{\alpha(x)\,|\;\, |x|=n\}$. It means,
$\cal A$ always correctly decides whether $x\in L$ or $x\notin L$, whenever it
outputs a decision. For some inputs, however, it may not output a decision,
rather it may return a special sign, meaning "don't know." But the latter can
happen only on an exponentially small fraction of each $\alpha$-sphere. We
prove that RoughP contains all paddable languages. This may contribute to the
explanation of the often observed gap between practical algorithm performance
and theoretical worst case analysis for hard problems. Furthermore, the proof
also provides a general method to construct the desired encoding and the
errorless heuristic. Additionally, we also show how to use it for efficiently
generating large, random, guaranteed positive and negative test instances for
any paddable language, including all known natural NP-complete problems. In
fact, it appears that every practical decision task (whether in NP or not) can
be represented by paddable languages, and, therefore, our RoughP framework
applies to all of them. We also explore some connections between RoughP and
other complexity classes.


title:
On the law of the iterated logarithm for Brownian motion on compact
  manifolds

abstract:
  By taking a functional analytic point of view, we consider a family of
distributions (continuous linear functionals on smooth functions), denoted by
$\{\mu_t,t>0\}$, associated to the law of iterated logarithm for Brownian
motion on a compact manifold. We give a complete characterization of the
collection of limiting distributions of $\{\mu_t, t>0\}$.


title:
Beam test results of a 16 ps timing system based on ultra-fast silicon
  detectors

abstract:
  In this paper we report on the timing resolution of the first production of
50 micro-meter thick Ultra-Fast Silicon Detectors (UFSD) as obtained in a beam
test with pions of 180 GeV/c momentum. UFSD are based on the Low-Gain Avalanche
Detectors (LGAD) design, employing n-on-p silicon sensors with internal charge
multiplication due to the presence of a thin, low-resistivity diffusion layer
below the junction. The UFSD used in this test belongs to the first production
of thin (50 {\mu}m) sensors, with an pad area of 1.4 mm2. The gain was measured
to vary between 5 and 70 depending on the bias voltage. The experimental setup
included three UFSD and a fast trigger consisting of a quartz bar readout by a
SiPM. The timing resolution, determined comparing the time of arrival of the
particle in one or more UFSD and the trigger counter, for single UFSD was
measured to be 35 ps for a bias voltage of 200 V, and 26 ps for a bias voltage
of 240 V, and for the combination of 3 UFSD to be 20 ps for a bias voltage of
200 V, and 15 ps for a bias voltage of 240 V.


title:
A Colored Petri Net Model of Simulation for Performance Evaluation for
  IEEE 802.22 based Network

abstract:
  Cognitive Radio is a new concept that allows radio devices access to licensed
bands since they do not cause harmful interferences to systems that hold the
license of use. The main motivation for the increase of research on Cognitive
Radio is the scarcity of non-licensed bands due to the large employment of
wireless networks on cities. In this paper, we describe a Cognitive Radio Model
of Simulation designed through the Colored Petri Net Formalism. This represents
an effort to deliver to scientific community a model of simulation that is
easily extensible and graphically validated. Through comparison with
literature, we have demonstrated that this model is not invalid.


title:
Invariance Control Synthesis for Switched Systems: An Interval Analysis
  Approach

abstract:
  This paper focuses on the invariance control problem for discrete-time
switched nonlinear systems. The proposed approach computes controlled invariant
sets in a finite number of iterations and directly yields a partition-based
invariance controller using the information recorded during the computation. In
contrast with Lyapunov-based control methods, this method does not require the
subsystems to have common equilibrium points. Algorithms are developed for
computing both outer and inner approximations of the maximal controlled
invariant sets, which are represented as finite unions of intervals. The
general convergence results of interval methods allow us to obtain arbitrarily
precise approximations without any stability assumptions. In addition,
invariant inner approximations can be computed provided that the switched
system satisfies a robustly controlled invariance condition. Under the same
condition, we also prove the existence of an invariance controller based on
partitions of the state space. Our method is illustrated with three examples
drawn from different applications and compared with existing work in the
literature.


title:
Is the local linearity of space-time inherited from the linearity of
  probabilities?

abstract:
  The appearance of linear spaces, describing physical quantities by vectors
and tensors, is ubiquitous in all of physics, from classical mechanics to the
modern notion of local Lorentz invariance. However, as natural as this seems to
the physicist, most computer scientists would argue that something like a
"local linear tangent space" is not very typical and in fact a quite surprising
property of any conceivable world or algorithm. In this paper, we take the
perspective of the computer scientist seriously, and ask whether there could be
any inherently information-theoretic reason to expect this notion of linearity
to appear in physics. We give a series of simple arguments, spanning quantum
information theory, group representation theory, and renormalization in quantum
gravity, that supports a surprising thesis: namely, that the local linearity of
space-time might ultimately be a consequence of the linearity of probabilities.
While our arguments involve a fair amount of speculation, they have the virtue
of being independent of any detailed assumptions on quantum gravity, and they
are in harmony with several independent recent ideas on emergent space-time in
high-energy physics.


title: Uniqueness Properties of Hardy Space Functions

abstract:
  We study boundary uniqueness properties of Hardy space functions in several
complex variables. Along the way, we develop properties of the Lumer Hardy
space.


title: Probing nuclear gluons with heavy quarks at EIC

abstract:
  We explore the feasibility of direct measurements of nuclear gluon densities
using heavy-quark production (open charm, beauty) at a future Electron-Ion
Collider (EIC). We focus on the regions x > 0.3 (EMC effect) and x ~ 0.05-0.1
(antishadowing), where the nuclear modifications of the gluon density offer
insight into non-nucleonic degrees of freedom and the QCD structure of
nucleon-nucleon interactions. We describe the charm production rates and
momentum distributions in nuclear deep-inelastic scattering (DIS) at large x_B,
and comment on the possible methods for charm reconstruction using
next-generation detectors at the EIC (pi/K identification, tracking, vertex
detection).


title:
Lattice based integration algorithms: Kronecker sequences and rank-1
  lattices

abstract:
  We prove upper bounds on the order of convergence of lattice based algorithms
for numerical integration in function spaces of dominating mixed smoothness on
the unit cube with homogeneous boundary condition. More precisely, we study
worst-case integration errors for Besov spaces of dominating mixed smoothness
$\mathring{\mathbf{B}}^s_{p,\theta}$, which also comprise the concept of
Sobolev spaces of dominating mixed smoothness $\mathring{\mathbf{H}}^s_{p}$ as
special cases. The considered algorithms are quasi-Monte Carlo rules with
underlying nodes from $T_N(\mathbb{Z}^d) \cap [0,1)^d$, where $T_N$ is a real
invertible generator matrix of size $d$. For such rules the worst-case error
can be bounded in terms of the Zaremba index of the lattice
$\mathbb{X}_N=T_N(\mathbb{Z}^d)$. We apply this result to Kronecker lattices
and to rank-1 lattice point sets, which both lead to optimal error bounds up to
$\log N$-factors for arbitrary smoothness $s$. The advantage of Kronecker
lattices and classical lattice point sets is that the run-time of algorithms
generating these point sets is very short.


title:
Nanosecond spin relaxation times in single layer graphene spin valves
  with hexagonal boron nitride tunnel barriers

abstract:
  We present an experimental study of spin transport in single layer graphene
using atomic sheets of hexagonal boron nitride (h-BN) as a tunnel barrier for
spin injection. While h-BN is expected to be favorable for spin injection,
previous experimental studies have been unable to achieve spin relaxation times
in the nanosecond regime, suggesting potential problems originating from the
contacts. Here, we investigate spin relaxation in graphene spin valves with
h-BN barriers and observe room temperature spin lifetimes in excess of a
nanosecond, which provides experimental confirmation that h-BN is indeed a good
barrier material for spin injection into graphene. By carrying out measurements
with different thicknesses of h-BN, we show that few layer h-BN is a better
choice than monolayer for achieving high non-local spin signals and longer spin
relaxation times in graphene.


title: Deleting Powers in Words

abstract:
  We consider the language consisting of all words such that it is possible to
obtain the empty word by iteratively deleting powers. It turns out that in the
case of deleting squares in binary words this language is regular, and in the
case of deleting squares in words over a larger alphabet the language is not
regular. However, for deleting squares over any alphabet we find that this
language can be generated by a linear index grammar which is a mildly context
sensitive grammar formalism. In the general case we show that this language is
generated by an indexed grammar.


title:
An Analytic Heuristic for Multiplicity Computation for Zaremba's
  Conjecture

abstract:
  Zaremba's Conjecture concerns the formation of continued fractions with
partial quotients restricted to a given alphabet. In order to answer the
numerous questions that arrive from this conjecture, it is best to consider a
semi-group, often denoted $\Gamma_{A}$, which arises naturally as a subset of
$SL_2(\mathbb{Z})$ when considering finite continued fractions. To translate
back from this semi-group into rational numbers, we select a projection mapping
satisfying certain criteria to recover the numerator and denominator of the
continued fractions in rational form. The central question of our research is
to determine the multiplicity of a given denominator. To this end, we develop a
heuristic method similar to the Hardy-Littlewood Circle Method. We compare this
theoretical model to the exact data, gleaned by simulation, and demonstrate
that our formula appears to be asymptotically valid. We then evaluate different
aspects of the accuracy of our formula.


title: One-Minute Derivation of The Conjugate Gradient Algorithm

abstract:
  One of the great triumphs in the history of numerical methods was the
discovery of the Conjugate Gradient (CG) algorithm. It could solve a symmetric
positive-definite system of linear equations of dimension N in exactly N steps.
As many practical problems at that time belonged to this category, CG algorithm
became rapidly popular. It remains popular even today due to its immense
computational power. But despite its amazing computational ability, mathematics
of this algorithm is not easy to learn. Lengthy derivations, redundant
notations, and over-emphasis on formal presentation make it much difficult for
a beginner to master this algorithm. This paper aims to serve as a starting
point for such readers. It provides a curt, easy-to-follow but minimalist
derivation of the algorithm by keeping the sufficient steps only, maintaining a
uniform notation, and focusing entirely on the ease of reader.


title: Efficient polarization of high-angular-momentum systems

abstract:
  We propose methods of optical pumping that are applicable to open,
high-angular-momentum transitions in atoms and molecules, for which
conventional optical pumping would lead to significant population loss. Instead
of applying circularly polarized cw light, as in conventional optical pumping,
we propose to use techniques for coherent population transfer (e.g., adiabatic
fast passage) to arrange the atoms so as to increase the entropy removed from
the system with each spontaneous decay from the upper state. This minimizes the
number of spontaneous-emission events required to produce a stretched state,
thus reducing the population loss due to decay to other states. To produce a
stretched state in a manifold with angular momentum J, conventional optical
pumping requires about 2J spontaneous decays per atom, one of our proposed
methods reduces this to about log_2(2J), while another of the methods reduces
it to about one spontaneous decay, independent of J.


title:
Numerical semigroups generated by squares, cubes and quartics of three
  consecutive integers

abstract:
  We derive the polynomial representations for minimal relations of generating
set of numerical semigroups R_n^k=<(n-1)^k,n^k,(n+1)^k>, k=2,3,4, n>2. We find
also the polynomial representations for degrees of syzygies in the Hilbert
series H(z,R_n^k) of these semigroups, their Frobenius numbers F(R_n^k) and
genera G(R_n^k).


title:
A Multi-Line Ammonia Survey of the Galactic Center Region with the
  Tsukuba 32-m Telescope - I. Observations and Data

abstract:
  We present survey data of the NH3 (J, K) = (1, 1)--(6, 6) lines,
simultaneously observed with the Tsukuba 32-m telescope, in the main part of
the central molecular zone of the Galaxy. The total number of on-source
positions was 2655. The lowest three transitions were detected with S/N > 3 at
2323 positions (93% of all the on-source positions). Among 2323, the S/N of (J,
K ) = (4, 4), (5, 5), and (6, 6) exceeded 3.0 at 1426 (54%), 1150 (43%), and
1359 (51%) positions, respectively. Simultaneous observations of the lines
enabled us to accurately derive intensity ratios with less systematic errors.
Boltzmann plots indicate there are two temperature components: cold ($\sim$ 20
K) and warm ($\sim$ 100 K). Typical intensity ratios of Tmb(2,2)/Tmb(1,1),
Tmb(4,4)/Tmb(2,2), Tmb(5,5)/Tmb(4,4), and Tmb(6,6)/Tmb(3,3) were 0.71, 0.45,
0.65, and 0.17, respectively. These line ratios correspond to diversity of
rotational temperature, which results from mixing of the two temperature
components.


title: Broken bridges: A counter-example of the ER=EPR conjecture

abstract:
  In this paper, we provide a counter-example to the ER=EPR conjecture. In an
anti-de Sitter space, we construct a pair of maximally entangled but separated
black holes. Due to the vacuum decay of the anti-de Sitter background toward a
deeper vacuum, these two parts can be trapped by bubbles. If these bubbles are
reasonably large, then within the scrambling time, there should appear an
Einstein-Rosen bridge between the two black holes. Now by tracing more details
on the bubble dynamics, one can identify parameters such that one of the two
bubbles either monotonically shrinks or expands. Because of the change of
vacuum energy, one side of the black hole would evaporate completely. Due to
the shrinking of the apparent horizon, a signal of one side of the
Einstein-Rosen bridge can be viewed from the opposite side. We analytically and
numerically demonstrate that within a reasonable semi-classical parameter
regime, such process can happen. Bubbles are a non-perturbative effect, which
is the crucial reason that allows the transmission of information between the
two black holes through the Einstein-Rosen bridge, even though the probability
is highly suppressed. Therefore, the ER=EPR conjecture cannot be generic in its
present form and its validity maybe restricted.


title: Characterization of the new scintillator CLYC

abstract:
  The first domestic inorganic scintillator CLYC was grown in Beijing Glass
Research Instituteusing the vertical Bridgman method. In this work, we
evaluated the performance of this new CLYC crystal in terms of gamma-ray energy
resolution and pulse shape discrimination(PSD)capability between neutrons and
gamma-rays. The decay times occurred throughdifferent scintillation mechanisms
were achievedby fitting decay functions to the neutron and gamma-ray waveform
structures. We found an energy resolution of 4.5% for 662-keV gamma-rays and
efficient neutron/gamma PSD withFoM 2.6. Under gamma-ray excitation, there is
ultrafast scintillation mechanism in CLYC, with a decay time about 2
ns,whereasthere is no evidence of ultrafast decay under thermal neutron
excitation. This work contributes to promote domestic development of CLYC.


title:
Proton distribution radii of $^{12-19}$C illuminate features of neutron
  halos

abstract:
  Proton radii of $^{12-19}$C densities derived from first accurate charge
changing cross section measurements at 900$A$ MeV with a carbon target are
reported. A thick neutron surface evolves from $\sim$ 0.5 fm in $^{15}$C to
$\sim$ 1 fm in $^{19}$C. The halo radius in $^{19}$C is found to be 6.4$\pm$0.7
fm as large as $^{11}$Li. Ab initio calculations based on chiral
nucleon-nucleon and three-nucleon forces reproduce well the radii.


title: Reconstructing parameters of spreading models from partial observations

abstract:
  Spreading processes are often modelled as a stochastic dynamics occurring on
top of a given network with edge weights corresponding to the transmission
probabilities. Knowledge of veracious transmission probabilities is essential
for prediction, optimization, and control of diffusion dynamics. Unfortunately,
in most cases the transmission rates are unknown and need to be reconstructed
from the spreading data. Moreover, in realistic settings it is impossible to
monitor the state of each node at every time, and thus the data is highly
incomplete. We introduce an efficient dynamic message-passing algorithm, which
is able to reconstruct parameters of the spreading model given only partial
information on the activation times of nodes in the network. The method is
generalizable to a large class of dynamic models, as well to the case of
temporal graphs.

categories: cs.SI cond-mat.dis-nn physics.soc-ph q-bio.PE stat.ML


title:
Convergence of $L^2$-norm based adaptive finite element method for
  elliptic optimal control problems

abstract:
  This paper aims to study the convergence of adaptive finite element method
for control constrained elliptic optimal control problems under $L^2$-norm. We
prove the contraction property and quasi-optimal complexity for the $L^2$-norm
errors of both the control, the state and adjoint state variables with
$L^2$-norm based AFEM, this is in contrast to and improve our previous work
[13] where convergence of AFEM based on energy norm had been studied and
suboptimal convergence for the control variable was obtained and observed
numerically. For the discretization we use variational discretization for the
control and piecewise linear and continuous finite elements for the state and
adjoint state. Under mild assumptions on the initial mesh and the mesh
refinement algorithm to keep the adaptive meshes sufficiently mildly graded we
prove the optimal convergence of AFEM for the control problems, numerical
results are provided to support our theoretical findings.


title: The K\"unneth Formula for the Twisted de Rham and Higgs Cohomologies

abstract:
  We prove the K\"unneth formula for the irregular Hodge filtrations on the
exponentially twisted de Rham and the Higgs cohomologies of smooth
quasi-projective complex varieties. The method involves a careful comparison of
the underlying chain complexes under a certain elimination of indeterminacy.


title:
Exactly solvable model for a solitonic vortex in a compressible
  superfluid

abstract:
  Vortex motion is a complex problem due to the interplay between the
short-range physics at the vortex core level and the long-range hydrodynamical
effects. Here we show that the hydrodynamic equations of vortex motion in a
compressible superfluid can be solved exactly in a model "slab" geometry.
Starting from an exact solution for an incompressible fluid, the hydrodynamic
equations are solved with a series expansion in a small tunable parameter
provided by the ratio of the healing length, characterizing the vortex cores,
to the slab width. The key dynamical properties of the vortex, the inertial and
physical masses, are well defined and renormalizable. They are calculated at
leading order beyond the logarithmic accuracy that has limited previous
approaches. Our results provide a solid framework for further detailed study of
the vortex mass and vortex forces in strongly-correlated and exotic
superfluids. The proposed geometry can be realised in quantum-gas experiments
where high-precision measurements of vortex mass parameters are feasible.


title: A note on graphs with exactly two main eigenvalues

abstract:
  In this note, we consider connected graphs with exactly two main eigenvalues.
We will give several constructions for them, and as a consequence we show a
family of those graphs with an unbounded number of distinct valencies.


title:
SEEDS direct imaging of the RV-detected companion to V450 Andromedae,
  and characterization of the system

abstract:
  We report the direct imaging detection of a low-mass companion to a young,
moderately active star V450 And, that was previously identified with the radial
velocity method. The companion was found in high-contrast images obtained with
the Subaru Telescope equipped with the HiCIAO camera and AO188 adaptive optics
system. From the public ELODIE and SOPHIE archives we extracted available
high-resolution spectra and radial velocity (RV) measurements, along with RVs
from the Lick planet search program. We combined our multi-epoch astrometry
with these archival, partially unpublished RVs, and found that the companion is
a low-mass star, not a brown dwarf, as previously suggested. We found the
best-fitting dynamical masses to be $m_1=1.141_{-0.091}^{+0.037}$ and
$m_2=0.279^{+0.023}_{-0.020}$ M$_\odot$. We also performed spectral analysis of
the SOPHIE spectra with the iSpec code. The Hipparcos time-series photometry
shows a periodicity of $P=5.743$ d, which is also seen in SOPHIE spectra as an
RV modulation of the star A. We interpret it as being caused by spots on the
stellar surface, and the star to be rotating with the given period. From the
rotation and level of activity, we found that the system is $380^{+220}_{-100}$
Myr old, consistent with an isochrone analysis ($220^{+2120}_{-90}$ Myr). This
work may serve as a test case for future studies of low-mass stars, brown
dwarfs and exoplanets by combination of RV and direct imaging data.


title:
Near-Optimal Lower Bounds on Quantifier Depth and Weisfeiler-Leman
  Refinement Steps

abstract:
  We prove near-optimal trade-offs for quantifier depth versus number of
variables in first-order logic by exhibiting pairs of $n$-element structures
that can be distinguished by a $k$-variable first-order sentence but where
every such sentence requires quantifier depth at least $n^{\Omega(k/\log k)}$.
Our trade-offs also apply to first-order counting logic, and by the known
connection to the $k$-dimensional Weisfeiler--Leman algorithm imply
near-optimal lower bounds on the number of refinement iterations.
  A key component in our proof is the hardness condensation technique recently
introduced by [Razborov '16] in the context of proof complexity. We apply this
method to reduce the domain size of relational structures while maintaining the
minimal quantifier depth to distinguish them in finite variable logics.


title: Charged spinning black holes as accelerators of spinning particles

abstract:
  It is well known that some black holes can act as accelerators for particles
without spin. Recently, there are some works considering collision of two
spinning particles in the background of Schwarzschild and Kerr black holes and
it was shown that {the center-of-mass energy of the test particles is related
to the spin}. In this paper we extend the results to some more general cases.
We consider Kerr-Newman black holes as accelerators for spinning particles. We
derive the center-of-mass energy of the spinning particles and use numerical
method to investigate how the center-of-mass energy is affected by the
properties of the black holes and spinning particles.


title:
Optically Detected Magnetic Resonances of Nitrogen-Vacancy Ensembles in
  13C Enriched Diamond

abstract:
  We present an experimental and theoretical study of the optically detected
magnetic resonance signals for ensembles of negatively charged nitrogen-vacancy
(NV) centers in 13C isotopically enriched single-crystal diamond. We observe
four broad transition peaks with superimposed sharp features at zero magnetic
field and study their dependence on applied magnetic field. A theoretical model
that reproduces all qualitative features of these spectra is developed.
Understanding the magnetic-resonance spectra of NV centers in isotopically
enriched diamond is important for emerging applications in nuclear magnetic
resonance.


title:
The BOSS Emission-Line Lens Survey. IV. : Smooth Lens Models for the
  BELLS GALLERY Sample

abstract:
  We present \textsl{Hubble Space Telescope} (\textsl{HST}) F606W-band imaging
observations of 21 galaxy-Ly$\alpha$ emitter lens candidates in the Baryon
Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey (BELLS) for
GALaxy-Ly$\alpha$ EmitteR sYstems (BELLS GALLERY) survey. 17 systems are
confirmed to be definite lenses with unambiguous evidence of multiple imaging.
The lenses are primarily massive early-type galaxies (ETGs) at redshifts of
approximately $0.55$, while the lensed sources are Ly$\alpha$ emitters (LAEs)
at redshifts from 2 to 3. Although the \textsl{HST} imaging data are well fit
by smooth lens models consisting of singular isothermal ellipsoids in an
external shear field, a thorough exploration of dark substructures in the lens
galaxies is required. The Einstein radii of the BELLS GALLERY lenses are on
average $60\%$ larger than those of the BELLS lenses because of the much higher
source redshifts which will allow a detailed investigation of the radius
evolution of the mass profile in ETGs. With the aid of the average $\sim 13
\times$ lensing magnification, the LAEs are resolved to comprise individual
star-forming knots of a wide range of properties with characteristic sizes from
less than 100 pc to several kpc, rest-frame far UV apparent AB magnitudes from
29.6 to 24.2, and typical projected separations of 500 pc to 2 kpc.


title: QCD monopole and sigma meson coupling

abstract:
  Under the assumption of the Abelian dominance in QCD, we show that chiral
condensate is locally present around a QCD monopole. The appearance of the
chiral condensate around a GUT monopole was shown in the previous analysis of
the Rubakov effect. We apply a similar analysis to the QCD monopole. It follows
that the condensation of the monopole carrying the chiral condensate leads to
the chiral symmetry breaking as well as quark confinement. To realize the
result explicitly, we present a phenomenological linear sigma model coupled
with the monopoles, in which the monopole condensation causes the chiral
symmetry breaking as well as confinement. The monopoles are assumed to be
described by a model of dual superconductor. Because the monopoles couple with
mesons, we point out the presence of an observable color singlet monopole
coupled with the mesons.


title: Vector duality via conditional extension of dual pairs

abstract:
  A Fenchel-Moreau type duality for proper convex and lower semi-continuous
functions $f\colon X\to \overline{L^0}$ is established where $(X,Y,\langle
\cdot,\cdot \rangle)$ is a dual pair of Banach spaces and $\overline{L^0}$ is
the set of all extended real-valued measurable functions. We provide a concept
of lower semi-continuity which is shown to be equivalent to the existence of a
dual representation in terms of elements in the Bochner space $L^0(Y)$. To
derive the duality result, several conditional completions and extensions are
constructed.
  This is an earlier version of arXiv e-print 1708.03127, where the main
results were formulated in an abstract setting of conditional completions,
conditional extensions and conditional real numbers.


title: Pruning Filters for Efficient ConvNets

abstract:
  The success of CNNs in various applications is accompanied by a significant
increase in the computation and parameter storage costs. Recent efforts toward
reducing these overheads involve pruning and compressing the weights of various
layers without hurting original accuracy. However, magnitude-based pruning of
weights reduces a significant number of parameters from the fully connected
layers and may not adequately reduce the computation costs in the convolutional
layers due to irregular sparsity in the pruned networks. We present an
acceleration method for CNNs, where we prune filters from CNNs that are
identified as having a small effect on the output accuracy. By removing whole
filters in the network together with their connecting feature maps, the
computation costs are reduced significantly. In contrast to pruning weights,
this approach does not result in sparse connectivity patterns. Hence, it does
not need the support of sparse convolution libraries and can work with existing
efficient BLAS libraries for dense matrix multiplications. We show that even
simple filter pruning techniques can reduce inference costs for VGG-16 by up to
34% and ResNet-110 by up to 38% on CIFAR10 while regaining close to the
original accuracy by retraining the networks.


title: Engagement Detection in Meetings

abstract:
  Group meetings are frequent business events aimed to develop and conduct
project work, such as Big Room design and construction project meetings. To be
effective in these meetings, participants need to have an engaged mental state.
The mental state of participants however, is hidden from other participants,
and thereby difficult to evaluate. Mental state is understood as an inner
process of thinking and feeling, that is formed of a conglomerate of mental
representations and propositional attitudes. There is a need to create
transparency of these hidden states to understand, evaluate and influence them.
Facilitators need to evaluate the meeting situation and adjust for higher
engagement and productivity. This paper presents a framework that defines a
spectrum of engagement states and an array of classifiers aimed to detect the
engagement state of participants in real time. The Engagement Framework
integrates multi-modal information from 2D and 3D imaging and sound. Engagement
is detected and evaluated at participants and aggregated at group level. We use
empirical data collected at the lab of Konica Minolta, Inc. to test initial
applications of this framework. The paper presents examples of the tested
engagement classifiers, which are based on research in psychology,
communication, and human computer interaction. Their accuracy is illustrated in
dyadic interaction for engagement detection. In closing we discuss the
potential extension to complex group collaboration settings and future feedback
implementations.


title: Nonintersecting Brownian bridges between reflecting or absorbing walls

abstract:
  We study a model of nonintersecting Brownian bridges on an interval with
either absorbing or reflecting walls at the boundaries, focusing on the point
in space-time at which the particles meet the wall. These processes are
determinantal, and in different scaling limits when the particles approach the
reflecting (resp. absorbing) walls we obtain hard-edge limiting kernels which
are the even (resp. odd) parts of the Pearcey and tacnode kernels. We also show
that in the single time case, our hard-edge tacnode kernels are equivalent to
the ones studied by Delvaux [16], defined in terms of a $4\times 4$ Lax pair
for the inhomogeneous Painlev\'{e} II equation (PII). As a technical ingredient
in the proof, we construct a Schlesinger transform for the $4 \times 4$ Lax
pair in [16] which preserves the Hastings--McLeod solutions to PII.


title:
The systematics of strong lens modeling quantified: the effects of
  constraint selection and redshift information on magnification, mass, and
  multiple image predictability

abstract:
  Until now, systematic errors in strong gravitational lens modeling have been
acknowledged but never been fully quantified. Here, we launch an investigation
into the systematics induced by constraint selection. We model the simulated
cluster Ares 362 times using random selections of image systems with and
without spectroscopic redshifts and quantify the systematics using several
diagnostics: image predictability, accuracy of model-predicted redshifts,
enclosed mass, and magnification. We find that for models with $>15$ image
systems, the image plane rms does not decrease significantly when more systems
are added; however the rms values quoted in the literature may be misleading as
to the ability of a model to predict new multiple images. The mass is well
constrained near the Einstein radius in all cases, and systematic error drops
to $<2\%$ for models using $>10$ image systems. Magnification errors are
smallest along the straight portions of the critical curve, and the value of
the magnification is systematically lower near curved portions. For $>15$
systems, the systematic error on magnification is $\sim2\%$. We report no trend
in magnification error with fraction of spectroscopic image systems when
selecting constraints at random; however, when using the same selection of
constraints, increasing this fraction up to $\sim0.5$ will increase model
accuracy. The results suggest that the selection of constraints, rather than
quantity alone, determines the accuracy of the magnification. We note that
spectroscopic follow-up of at least a few image systems is crucial, as models
without any spectroscopic redshifts are inaccurate across all of our
diagnostics.


title:
ALMA View of the Galactic Center Mini-spiral: Ionized Gas Flows around
  Sagittarius A*

abstract:
  We have performed the observation of the "Galactic Center Mini-spiral(GCMS)"
in H42alpha recombination line as a part of the first large-scale mosaic
observation in the Sagittarius A complex using Atacama
Millimeter/sub-millimeter Array (ALMA). We revealed the kinematics of the
ionized gas streamers of the GCMS. We found that the ionized gas streamers of
the Northern Arm(NA) and Eastern Arm(EA) in their outer regions somewhat
deviate from the Keplerian orbits which were derived previously from the
trajectories in the inner regions. In addition, we found that the streamer
corresponding to the Bar of the GCMS has a Keplerian orbit with an eccentricity
of e~0.8, which is independent from the Keplerian orbits of the other streamers
of the GCMS. We estimated the LTE electron temperature and electron density in
the ionized gas streamers. We confirmed the previously claimed tendency that
the electron temperatures increase toward Sgr A*. We found that the electron
density in the NA and EA also increases with approaching Sgr A* without the
lateral expansion of the gas streamers. This suggests that there is some
external pressure around the GCMS. The ambient ionized gas may cause the
confinement and/or the perturbation for the orbits. There is a good positional
correlation between the protostar candidates detected by JVLA at 34 GHz and the
ionized gas streamer, Northeastern Arm, newly found by our H42alpha
recombination line observation. This suggests that the candidates had formed in
the streamer and they were brought to near Sgr A* as the streamer falls.


title:
Epidemic extinction in a generalized susceptible-infected-susceptible
  model

abstract:
  We study the extinction of epidemics in a generalized
susceptible-infected-susceptible model, where a susceptible individual becomes
infected with the rate $\lambda$ when contacting $m$ infective individual(s)
simultaneously, and an infected individual spontaneously recovers with the rate
$\mu$. By employing the Wentzel-Kramers-Brillouin approximation for the master
equation, the problem is reduced to finding the zero-energy trajectories in an
effective Hamiltonian system, and the mean extinction time $\langle T\rangle$
depends exponentially on the associated action $\mathcal {S}$ and the size of
the population $N$, $\langle T\rangle \sim \exp(N\mathcal {S})$. Because of
qualitatively different bifurcation features for $m=1$ and $m\geq2$, we derive
independently the expressions of $\mathcal {S}$ as a function of the rescaled
infection rate $\lambda/\mu$. For the weak infection, $\mathcal {S}$ scales to
the distance to the bifurcation with an exponent $2$ for $m=1$ and $3/2$ for
$m\geq2$. Finally, a rare-event simulation method is used to validate the
theory.


title: Measuring Machine Intelligence Through Visual Question Answering

abstract:
  As machines have become more intelligent, there has been a renewed interest
in methods for measuring their intelligence. A common approach is to propose
tasks for which a human excels, but one which machines find difficult. However,
an ideal task should also be easy to evaluate and not be easily gameable. We
begin with a case study exploring the recently popular task of image captioning
and its limitations as a task for measuring machine intelligence. An
alternative and more promising task is Visual Question Answering that tests a
machine's ability to reason about language and vision. We describe a dataset
unprecedented in size created for the task that contains over 760,000 human
generated questions about images. Using around 10 million human generated
answers, machines may be easily evaluated.


title: Toward computerized efficient estimation in infinite-dimensional models

abstract:
  Despite the risk of misspecification they are tied to, parametric models
continue to be used in statistical practice because they are accessible to all.
In particular, efficient estimation procedures in parametric models are simple
to describe and implement. Unfortunately, the same cannot be said of
semiparametric and nonparametric models. While the latter often reflect the
level of available scientific knowledge more appropriately, performing
efficient inference in these models is generally challenging. The efficient
influence function is a key analytic object from which the construction of
asymptotically efficient estimators can potentially be streamlined. However,
the theoretical derivation of the efficient influence function requires
specialized knowledge and is often a difficult task, even for experts. In this
paper, we propose and discuss a numerical procedure for approximating the
efficient influence function. The approach generalizes the simple nonparametric
procedures described recently by Frangakis et al. (2015) and Luedtke et al.
(2015) to arbitrary models. We present theoretical results to support our
proposal, and also illustrate the method in the context of two examples. The
proposed approach is an important step toward automating efficient estimation
in general statistical models, thereby rendering the use of realistic models in
statistical analyses much more accessible.


title:
Reconciling forecasts of infant mortality rates at national and
  sub-national levels: Grouped time-series methods

abstract:
  Mortality rates are often disaggregated by different attributes, such as sex,
state, education, religion or ethnicity. Forecasting mortality rates at the
national and sub-national levels plays an important role in making social
policies associated with the national and sub-national levels. However, base
forecasts at the sub-national levels may not add up to the forecasts at the
national level. To address this issue, we consider the problem of reconciling
mortality rate forecasts from the viewpoint of grouped time-series forecasting
methods (Hyndman et al., 2011). A bottom-up method and an optimal combination
method are applied to produce point forecasts of infant mortality rates that
are aggregated appropriately across the different levels of a hierarchy. We
extend these two methods by considering the reconciliation of interval
forecasts through a bootstrap procedure. Using the regional infant mortality
rates in Australia, we investigate the one-step-ahead to 20-step-ahead point
and interval forecast accuracies among the independent and these two grouped
time-series forecasting methods. The proposed methods are shown to be useful
for reconciling point and interval forecasts of demographic rates at the
national and sub-national levels, and would be beneficial for government policy
decisions regarding the allocations of current and future resources at both the
national and sub-national levels.


title: Floquet Semimetal with Floquet-band Holonomy

abstract:
  Exotic topological states of matter such as Floquet topological insulator or
Floquet Weyl semimetal can be induced by periodic driving. This work proposes a
Floquet semimetal with Floquet-band holonomy. That is, the system is gapless,
but as a periodic parameter viewed as quasimomentum of a synthetic dimension
completes an adiabatic cycle, each Floquet band as a whole exchanges with other
Floquet bands. The dynamical manifestations of such Floquet-band holonomy are
studied. Under open boundary conditions, we discover anomalous chiral edge
modes localized only at one edge, winding around the entire quasienergy
Brillouin zone, well separated from bulk states, and possessing holonomy
different from bulk states. These remarkable properties are further exploited
to realize quantized or half-quantized edge state pumping.


title:
Exact nonequilibrium dynamics of finite-temperature Tonks-Girardeau
  gases

abstract:
  Describing finite-temperature nonequilibrium dynamics of interacting
many-particle systems is a notoriously challenging problem in quantum many-body
physics. Here we provide an exact solution to this problem for a system of
strongly interacting bosons in one dimension in the Tonks-Girardeau regime of
infinitely strong repulsive interactions. Using the Fredholm determinant
approach and the Bose-Fermi mapping we show how the problem can be reduced to a
single-particle basis, wherein the finite-temperature effects enter the
solution via an effective "dressing" of the single-particle wavefunctions by
the Fermi-Dirac occupation factors. We demonstrate the utility of our approach
and its computational efficiency in two nontrivial out-of-equilibrium
scenarios: collective breathing mode oscillations in a harmonic trap and
collisional dynamics in the Newton's cradle setting involving real-time
evolution in a periodic Bragg potential.


title: Balanced Manifolds and SKT Metrics

abstract:
  The equality between the balanced and the Gauduchon cones is discussed in
several situations. In particular, it is shown that equality does not hold on
many twistor spaces, and it holds on Moishezon manifolds. Moreover, it is
proved that a SKT manifold of dimension three on which the balanced cone equals
the Gauduchon cone is in fact Kahler.


title: Exit Time Moments and Eigenvalue Estimates

abstract:
  We study estimates involving the principal Dirichlet eigenvalue associated to
a smoothly bounded domain in a complete Riemannian manifold and L1-norms of
exit time moments of Brownian motion. Our results generalize a classical
inequality of Polya.


title: \tau-rigid modules over Auslander algebras

abstract:
  We give a characterization of $\tau$-rigid modules over Auslander algebras in
terms of projective dimension of modules. Moreover, we show that for an
Auslander algebra $\Lambda$ admitting finite number of non-isomorphic basic
tilting $\Lambda$-modules and tilting $\Lambda^{op}$-modules, if all
indecomposable $\tau$-rigid $\Lambda$-modules of projective dimension $2$ are
of grade $2$, then $\Lambda$ is $\tau$-tilting finite.


title: A Programming Language With a POMDP Inside

abstract:
  We present POAPS, a novel planning system for defining Partially Observable
Markov Decision Processes (POMDPs) that abstracts away from POMDP details for
the benefit of non-expert practitioners. POAPS includes an expressive adaptive
programming language based on Lisp that has constructs for choice points that
can be dynamically optimized. Non-experts can use our language to write
adaptive programs that have partially observable components without needing to
specify belief/hidden states or reason about probabilities. POAPS is also a
compiler that defines and performs the transformation of any program written in
our language into a POMDP with control knowledge. We demonstrate the generality
and power of POAPS in the rapidly growing domain of human computation by
describing its expressiveness and simplicity by writing several POAPS programs
for common crowdsourcing tasks.


title: Making On-Demand Routing Efficient with Route-Request Aggregation

abstract:
  In theory, on-demand routing is very attractive for mobile ad hoc networks
(MANET), because it induces signaling only for those destinations for which
there is data traffic. However, in practice, the signaling overhead of existing
on-demand routing protocols becomes excessive as the rate of topology changes
increases due to mobility or other causes. We introduce the first on-demand
routing approach that eliminates the main limitation of on-demand routing by
aggregating route requests (RREQ) for the same destinations. The approach can
be applied to any existing on-demand routing protocol, and we introduce the
Ad-hoc Demand-Aggregated Routing with Adaptation (ADARA) as an example of how
RREQ aggregation can be used. ADARA is compared to AODV and OLSR using
discrete-event simulations, and the results show that aggregating RREQs can
make on-demand routing more efficient than existing proactive or on-demand
routing protocols.


title: Alignment of wave functions for angular momentum projection

abstract:
  Angular momentum projection is used to obtain eigen states of angular
momentum from general wave functions. Multi-configuration mixing calculation
with angular momentum projection is an important microscopic method in nuclear
physics. For accurate multi-configuration mixing calculation with angular
momentum projection, concentrated distribution of $z$ components $K$ of angular
momentum in the body-fixed frame ($K$-distribution) is favored. Orientation of
wave functions strongly affects $K$-distribution. Minimization of variance of
$\hat{J}_z$ is proposed as an alignment method to obtain wave functions that
have concentrated $K$-distribution. Benchmark calculations are performed for
$\alpha$-$^{24}$Mg cluster structure, triaxially superdeformed states in
$^{40}$Ar, and Hartree-Fock states of some nuclei. The proposed alignment
method is useful and works well for various wave functions to obtain
concentrated $K$-distribution.