title:
Understanding inverse metallicity gradients in galactic discs as a
  consequence of inside-out formation

abstract:
  The early stages of a galaxy's evolution leave an imprint on its metallicity
distribution. We discuss the origins and evolution of radial metallicity
gradients in discs of spiral galaxies using an analytical chemical evolution
model. We explain how radial metallicity gradients in stellar populations are
determined by three factors: the radial metallicity profile of the star-forming
ISM, radial changes in the star-formation history (in particular inside-out
formation), and radial mixing of stars. Under reasonable assumptions,
inside-out formation steepens the negative ISM metallicity gradient, but
contributes positively to the stellar metallicity gradient, up to inverting the
metallicity profile to a positive d[Fe/H]/dR. This reconciles steep negative
d[Fe/H]/dR in some high redshift galaxies to generally flatter gradients in
local observations.
  We discuss the evidence for inverse radial metallicity gradients (positive
d[X/H]/dR) at high redshifts and the inverse relationship between azimuthal
velocity and the metallicity (positive dV_{\phi}/d[Fe/H]) of stars for the
Milky Way's thick disc. The former can be achieved by high central gas-loss
rates and re-distribution processes, e.g. re-accretion of enriched material in
conjunction with inside-out formation, and near-disc galactic fountaining. For
the Milky Way thick disc, we show that the positive dV_{\phi}/d[Fe/H]
correlation points to comparable timescales for inside-out formation, initial
metal enrichment and SNIa enrichment. We argue that the original ISM
metallicity gradient could be inferred with better data from the
high-metallicity tail of the alpha enhanced population. Including inside-out
formation in our models changes the local vertical metallicity gradient by
about -0.2dex/kpc, in line with local measurements.


title:
Experimental creation of superposition of unknown photonic quantum
  states

abstract:
  As one of the most intriguing intrinsic properties of quantum world, quantum
superposition provokes great interests in its own generation. Oszmaniec [Phys.
Rev. Lett. 116, 110403 (2016)] have proven that though a universal quantum
machine that creates superposition of arbitrary two unknown states is
physically impossible, a probabilistic protocol exists in the case of two input
states have nonzero overlaps with the referential state. Here we report a
heralded quantum machine realizing superposition of arbitrary two unknown
photonic qubits as long as they have nonzero overlaps with the horizontal
polarization state $|H\rangle$. A total of 11 different qubit pairs are chosen
to test this protocol by comparing the reconstructed output state with
theoretical expected superposition of input states. We obtain the average
fidelity as high as 0.99, which shows the excellent reliability of our
realization. This realization not only deepens our understanding of quantum
superposition but also has significant applications in quantum information and
quantum computation, e.g., generating non-classical states in the context of
quantum optics and realizing information compression by coherent superposition
of results of independent runs of subroutines in a quantum computation.


title: Convex integration with linear constraints and its applications

abstract:
  We study solutions of the first order partial differential inclusions of the
form $\nabla u\in K$, where $u:\Omega\subset\mathbb{R}^n\to\mathbb{R}^m$ and
$K$ is a set of $m\times n$ real matrices, and derive a companion version to
the result of {M\"uller and \v{S}ver\'ak} [20], concerning a general linear
constraint on the components of $\nabla u$. We then consider two applications:
the vectorial eikonal equation and a $T_4$-configuration both under linear
constraints.


title: Accelerated reconstruction of a compressively sampled data stream

abstract:
  The traditional compressed sensing approach is naturally offline, in that it
amounts to sparsely sampling and reconstructing a given dataset. Recently, an
online algorithm for performing compressed sensing on streaming data was
proposed: the scheme uses recursive sampling of the input stream and recursive
decompression to accurately estimate stream entries from the acquired noisy
measurements.
  In this paper, we develop a novel Newton-type forward-backward proximal
method to recursively solve the regularized Least-Squares problem (LASSO)
online. We establish global convergence of our method as well as a local
quadratic convergence rate. Our simulations show a substantial speed-up over
the state of the art which may render the proposed method suitable for
applications with stringent real-time constraints.


title: Basin entropy: a new tool to analyze uncertainty in dynamical systems

abstract:
  In nonlinear dynamics, basins of attraction link a given set of initial
conditions to its corresponding final states. This notion appears in a broad
range of applications where several outcomes are possible, which is a common
situation in neuroscience, economy, astronomy, ecology and many other
disciplines. Depending on the nature of the basins, prediction can be difficult
even in systems that evolve under deterministic rules. From this respect, a
proper classification of this unpredictability is clearly required. To address
this issue, we introduce the basin entropy, a measure to quantify this
uncertainty. Its application is illustrated with several paradigmatic examples
that allow us to identify the ingredients that hinder the prediction of the
final state. The basin entropy provides an efficient method to probe the
behavior of a system when different parameters are varied. Additionally, we
provide a sufficient condition for the existence of fractal basin boundaries:
when the basin entropy of the boundaries is larger than $\log 2 $, the basin is
fractal.


title:
Equivalences between weight modules via $\mathcal{N}=2$ coset
  constructions

abstract:
  In this paper we introduce a variant of weight modules for certain conformal
vertex superalgebras as an appropriate framework of the $\mathcal{N}=2$
supersymmetric coset construction. We call them weight-wise admissible modules.
Motivated by the work of Feigin-Semikhatov-Tipunin, we give (block-wise)
categorical equivalences between the categories of weight-wise admissible
modules over $\widehat{\mathfrak{sl}}_{2}$ and the $\mathcal{N}=2$
superconformal algebra, induced by the coset construction. As an application,
we obtain some character formulae of modules over the $\mathcal{N}=2$
superconformal algebra.


title:
Specific heat and entropy of fractional quantum Hall states in the
  second Landau level

abstract:
  Specific heat has had an important role in the study of superfluidity and
superconductivity, and could provide important information about the fractional
quantum Hall effect as well. However, traditional measurements of the specific
heat of a two-dimensional electron gas are difficult due to the large
background contribution of the phonon bath, even at very low temperatures.
Here, we report measurements of the specific heat per electron in the second
Landau level by measuring the thermalization time between the electrons and
phonons. We observe activated behaviour of the specific heat of the 5/2 and 7/3
fractional quantum Hall states, and extract the entropy by integrating over
temperature. Our results are in excellent agreement with previous measurements
of the entropy via longitudinal thermopower. Extending the technique to lower
temperatures could lead to detection of the non-Abelian entropy predicted for
bulk quasiparticles at 5/2 filling


title:
On the splitting problem for Lorentzian manifolds with an
  $\mathbb{R}$-action with causal orbits

abstract:
  We study the interplay between the global causal and geometric structures of
a spacetime $(M,g)$ and the features of a given smooth $\mathbb{R}$-action
$\rho$ on $M$ whose orbits are all causal curves, building on classic results
about Lie group actions on manifolds described by Palais. In the first part of
this paper, we prove that $\rho$ is free and proper (so that $M$ splits
topologically) provided that $(M,g)$ is strongly causal and $\rho$ does not
have what we call weakly ancestral pairs, a notion which admits a natural
interpretation in terms of "cosmic censorship". Accordingly, such condition
holds automatically if $(M,g)$ is globally hyperbolic. We also prove that $M$
splits topologically if $(M,g)$ is strongly causal and $\rho$ is the flow of a
complete conformal Killing causal vector field. In the second part, we
investigate the class of Brinkmann spacetimes, which can be regarded as null
analogues of stationary spacetimes in which $\rho$ is the flow of a complete
parallel null vector field. Inspired by the geometric characterization of
stationary spacetimes in terms of standard stationary ones [24], we obtain an
analogous geometric characterization of when a Brinkmann spacetime is isometric
to a standard Brinkmann spacetime. This result naturally leads us to discuss a
conjectural null analogue for Ricci-flat $4$-dimensional Brinkmann spacetimes
of a celebrated rigidity theorem by Anderson [1], and highlight its relation
with a long-standing 1962 conjecture by Ehlers and Kundt [13]. If true, our
conjecture provides strong mathematical support to the idea that gravitational
plane waves are the most natural "boundary conditions" at infinity for vacuum
solutions of the Einstein equation modeling regions outside gravitationally
radiating sources.


title: Chained Predictions Using Convolutional Neural Networks

abstract:
  In this paper, we present an adaptation of the sequence-to-sequence model for
structured output prediction in vision tasks. In this model the output
variables for a given input are predicted sequentially using neural networks.
The prediction for each output variable depends not only on the input but also
on the previously predicted output variables. The model is applied to spatial
localization tasks and uses convolutional neural networks (CNNs) for processing
input images and a multi-scale deconvolutional architecture for making spatial
predictions at each time step. We explore the impact of weight sharing with a
recurrent connection matrix between consecutive predictions, and compare it to
a formulation where these weights are not tied. Untied weights are particularly
suited for problems with a fixed sized structure, where different classes of
output are predicted in different steps. We show that chained predictions
achieve top performing results on human pose estimation from single images and
videos.


title:
The Power and Limits of Predictive Approaches to
  Observational-Data-Driven Optimization

abstract:
  While data-driven decision-making is transforming modern operations, most
large-scale data is of an observational nature, such as transactional records.
These data pose unique challenges in a variety of operational problems posed as
stochastic optimization problems, including pricing and inventory management,
where one must evaluate the effect of a decision, such as price or order
quantity, on an uncertain cost/reward variable, such as demand, based on
historical data where decision and outcome may be confounded. Often, the data
lacks the features necessary to enable sound assessment of causal effects
and/or the strong assumptions necessary may be dubious. Nonetheless, common
practice is to assign a decision an objective value equal to the best
prediction of cost/reward given the observation of the decision in the data.
While in general settings this identification is spurious, for optimization
purposes it is only the objective value of the final decision that matters,
rather than the validity of any model used to arrive at it. In this paper, we
formalize this statement in the case of observational-data-driven optimization
and study both the power and limits of predictive approaches to
observational-data-driven optimization with a particular focus on pricing. We
provide rigorous bounds on optimality gaps of such approaches even when optimal
decisions cannot be identified from data. To study potential limits of
predictive approaches in real datasets, we develop a new hypothesis test for
causal-effect objective optimality. Applying it to interest-rate-setting data,
we empirically demonstrate that predictive approaches can be powerful in
practice but with some critical limitations.


title:
Configuration space method for calculating binding energies of exciton
  complexes in quasi-1D/2D semiconductors

abstract:
  A configuration space method is developed for binding energy calculations of
the lowest energy exciton complexes (trion, biexciton) in spatially confined
quasi-1D semiconductor nanostructures such as nanowires and nanotubes. Quite
generally, trions are shown to have greater binding energy in strongly confined
structures with small reduced electron-hole masses. Biexcitons have greater
binding energy in less confined structures with large reduced electron-hole
masses. This results in a universal crossover behavior, whereby trions become
less stable than biexcitons as the transverse size of the quasi-1D
nanostructure increases. The method is also capable of evaluating binding
energies for electron-hole complexes in quasi-2D semiconductors such as coupled
quantum wells and bilayer van der Walls bound heterostructures with advanced
optoelectronic properties.


title:
On Secrecy Rates and Outage in Multi-User Multi-Eavesdroppers MISO
  Systems

abstract:
  In this paper, we study the secrecy rate and outage probability in
Multiple-Input-Single-Output (MISO) Gaussian wiretap channels at the limit of a
large number of legitimate users and eavesdroppers. In particular, we analyze
the asymptotic achievable secrecy rates and outage, when only statistical
knowledge on the wiretap channels is available to the transmitter.
  The analysis provides exact expressions for the reduction in the secrecy rate
as the number of eavesdroppers grows, compared to the boost in the secrecy rate
as the number of legitimate users grows.


title: Proving Liveness of Parameterized Programs

abstract:
  Correctness of multi-threaded programs typically requires that they satisfy
liveness properties. For example, a program may require that no thread is
starved of a shared resource, or that all threads eventually agree on a single
value. This paper presents a method for proving that such liveness properties
hold. Two particular challenges addressed in this work are that (1) the
correctness argument may rely on global behaviour of the system (e.g., the
correctness argument may require that all threads collectively progress towards
"the good thing" rather than one thread progressing while the others do not
interfere), and (2) such programs are often designed to be executed by any
number of threads, and the desired liveness properties must hold regardless of
the number of threads that are active in the program.


title:
Variance component score test for time-course gene set analysis of
  longitudinal RNA-seq data

abstract:
  As gene expression measurement technology is shifting from microarrays to
sequencing, the statistical tools available for their analysis must be adapted
since RNA-seq data are measured as counts. Recently, it has been proposed to
tackle the count nature of these data by modeling log-count reads per million
as continuous variables, using nonparametric regression to account for their
inherent heteroscedasticity. Adopting such a framework, we propose tcgsaseq, a
principled, model-free and efficient top-down method for detecting longitudinal
changes in RNA-seq gene sets. Considering gene sets defined a priori, tcgsaseq
identifies those whose expression vary over time, based on an original variance
component score test accounting for both covariates and heteroscedasticity
without assuming any specific parametric distribution for the transformed
counts. We demonstrate that despite the presence of a nonparametric component,
our test statistic has a simple form and limiting distribution, and both may be
computed quickly. A permutation version of the test is additionally proposed
for very small sample sizes. Applied to both simulated data and two real
datasets, the proposed method is shown to exhibit very good statistical
properties, with an increase in stability and power when compared to state of
the art methods ROAST, edgeR and DESeq2, which can fail to control the type I
error under certain realistic settings. We have made the method available for
the community in the R package tcgsaseq.


title:
Process convergence for the complexity of Radix Selection on Markov
  sources

abstract:
  A fundamental algorithm for selecting ranks from a finite subset of an
ordered set is Radix Selection. This algorithm requires the data to be given as
strings of symbols over an ordered alphabet, e.g., binary expansions of real
numbers. Its complexity is measured by the number of symbols that have to be
read. In this paper the model of independent data identically generated from a
Markov chain is considered. The complexity is studied as a stochastic process
indexed by the set of infinite strings over the given alphabet. The orders of
mean and variance of the complexity and, after normalization, a limit theorem
with a centered Gaussian process as limit are derived. This implies an analysis
for two standard models for the ranks: uniformly chosen ranks, also called
grand averages, and the worst case rank complexities which are of interest in
computer science. For uniform data and the asymmetric Bernoulli model (i.e.
memoryless sources), we also find weak convergence for the normalized process
of complexities when indexed by the ranks while for more general Markov sources
these processes are not tight under the standard normalizations.


title:
Approximate Gaussian Elimination for Laplacians: Fast, Sparse, and
  Simple

abstract:
  We show how to perform sparse approximate Gaussian elimination for Laplacian
matrices. We present a simple, nearly linear time algorithm that approximates a
Laplacian by a matrix with a sparse Cholesky factorization, the version of
Gaussian elimination for symmetric matrices. This is the first nearly linear
time solver for Laplacian systems that is based purely on random sampling, and
does not use any graph theoretic constructions such as low-stretch trees,
sparsifiers, or expanders. The crux of our analysis is a novel concentration
bound for matrix martingales where the differences are sums of conditionally
independent variables.


title: Converse theorems: from the Riemann zeta function to the Selberg class

abstract:
  This is an expanded version of the author's lecture at the XX Congresso
U.M.I., held in Siena in September 2015. After a brief review of L-functions,
we turn to the classical converse theorems of H.Hamburger, E.Hecke and A.Weil,
and to some later developments. Finally we present several results on converse
theorems in the framework of the Selberg class of L-functions.


title:
Unconditionally secure credit/debit card chip scheme and physical
  unclonable function

abstract:
  The statistical-physics-based Kirchhoff-law-Johnson-noise (KLJN) key exchange
offers a new and simple unclonable system for credit/debit card chip
authentication and payment. The key exchange, the authentication and the
communication are unconditionally secure so that neither mathematics- nor
statistics-based attacks are able to crack the scheme. The ohmic connection and
the short wiring lengths between the chips in the card and the terminal
constitute an ideal setting for the KLJN protocol, and even its simplest
versions offer unprecedented security and privacy for credit/debit card chips
and applications of physical unclonable functions.


title: Moduli spaces of flat tori and elliptic hypergeometric functions

abstract:
  In the genus one case, we make explicit some constructions of Veech on flat
surfaces and generalize some geometric results of Thurston about moduli spaces
of flat spheres as well as some equivalent ones but of an
analytico-cohomological nature of Deligne-Mostow, which concern the monodromy
of Appell-Lauricella hypergeometric functions.
  In the twin paper arXiv:1604.01812, we follow Thurston's approach and study
moduli spaces of flat tori with conical singularities and prescribed holonomy
by means of geometrical methods relying on surgeries for flat surfaces.
  In the present paper, we study the same objects making use of analytical and
cohomological methods, more in the spirit of Deligne-Mostow's paper.


title: Dynamics of a Mobile Impurity in a One-Dimensional Bose Liquid

abstract:
  We develop a microscopic theory of a quantum impurity propagating in a
one-dimensional Bose liquid. As a result of scattering off thermally excited
quasiparticles, the impurity experiences the friction. We find that, at low
temperatures, the resulting force scales either as the fourth or the eighth
power of temperature, depending on the system parameters. For temperatures
higher than the chemical potential of the Bose liquid, the friction force is a
linear function of temperature. Our approach enables us to find the friction
force in the crossover region between the two limiting cases. In the integrable
case, corresponding to the Yang-Gaudin model, the impurity becomes transparent
for quasiparticles and thus the friction force is absent. Our results could be
further generalized to study other kinetic phenomena.


title:
Regulation of black-hole accretion by a disk wind during a violent
  outburst of V404 Cygni

abstract:
  Accretion of matter onto black holes is universally associated with strong
radiative feedback and powerful outflows. In particular, black hole transients
show outflows whose properties are strongly coupled to those of the accretion
flow. This includes X-ray winds of ionized material, expelled from the
accretion disc encircling the black hole, and collimated radio jets. Very
recently, a distinct optical variability pattern has been reported in the
transient black hole transient V404 Cyg, and interpreted as disrupted mass flow
into the inner regions of its large accretion disc. Here, we report on the
discovery of a sustained outer accretion disc wind in V404 Cyg, which is unlike
any seen previously. We find that the outflowing wind is neutral, has a large
covering factor, expands at 1% of the speed of light and triggers a nebular
phase once accretion sharply drops and the ejecta become optically thin. The
large expelled mass (> 10^-8 Msun) indicates that the outburst was prematurely
ended when a sizeable fraction of the outer disc was depleted by the wind,
detaching the inner regions from the rest of the disc. The luminous, but brief,
accretion phases shown by transients with large accretion discs imply that this
outflow is most likely a new fundamental ingredient regulating mass accretion
onto black holes.


title: An algorithm for computing the 2D structure of fast rotating stars

abstract:
  Stars may be understood as self-gravitating masses of a compressible fluid
whose radiative cooling is compensated by nuclear reactions or gravitational
contraction. The understanding of their time evolution requires the use of
detailed models that account for a complex microphysics including that of
opacities, equation of state and nuclear reactions. The present stellar models
are essentially one-dimensional, namely spherically symmetric. However, the
interpretation of recent data like the surface abundances of elements or the
distribution of internal rotation have reached the limits of validity of
one-dimensional models because of their very simplified representation of
large-scale fluid flows. In this article, we describe the ESTER code, which is
the first code able to compute in a consistent way a two-dimensional model of a
fast rotating star including its large-scale flows. Compared to classical 1D
stellar evolution codes, many numerical innovations have been introduced to
deal with this complex problem. First, the spectral discretization based on
spherical harmonics and Chebyshev polynomials is used to represent the 2D
axisymmetric fields. A nonlinear mapping maps the spheroidal star and allows a
smooth spectral representation of the fields. The properties of Picard and
Newton iterations for solving the nonlinear partial differential equations of
the problem are discussed. It turns out that the Picard scheme is efficient on
the computation of the simple polytropic stars, but Newton algorithm is
unsurpassed when stellar models include complex microphysics. Finally, we
discuss the numerical efficiency of our solver of Newton iterations. This
linear solver combines the iterative Conjugate Gradient Squared algorithm
together with an LU-factorization serving as a preconditionner of the Jacobian
matrix.


title: A note on semicentral Idempotents

abstract:
  In this note we answer the question raised by Han et al. in J. Korean Math.
Soc (2014) whether an idempotent isomorphic to a semicentral idempotent is
itself semicentral. We show that rings with this property are precisely the
Dedekind-finite rings. An application to module theory is given.


title:
On the subword complexity of the fixed point of $a \rightarrow aab$, $b
  \rightarrow b$, and generalizations

abstract:
  We find an explicit closed form for the subword complexity of the infinite
fixed point of the morphism sending $a \rightarrow aab$ and $b \rightarrow b$.
This morphism is then generalized in three different ways, and we find similar
explicit expressions for the subword complexity of the generalizations.


title:
Geometric Correction in Diffusive Limit of Neutron Transport Equation in
  2D Convex Domains

abstract:
  Consider the steady neutron transport equation with diffusive boundary
condition. In [Wu and Guo(2015) Comm. Math. Phys.] and [Wu and Yang and
Guo(2016) Preprint], it was discovered that geometric correction is necessary
for the Milne problem of Knudsen-layer construction in a disk or annulus. In
this paper, we establish diffusive limit for a 2D convex domain. Our
contribution relies on novel $W^{1,\infty}$ estimates for the Milne problem
with geometric correction in the presence of a convex domain, as well as an
$L^{2m}-L^{\infty}$ framework which yields stronger remainder estimates.


title:
Quantitative uniqueness for elliptic equations at the boundary of $C^{1,
  Dini}$ domains

abstract:
  Based on a variant of the frequency function approach of Almgren, we
establish an optimal upper bound on the vanishing order of solutions to
variable coefficient Schr\"odinger equations at a portion of the boundary of a
$C^{1,Dini}$ domain. Such bound provides a quantitative form of strong unique
continuation at the boundary. It can be thought of as a boundary analogue of an
interior result recently obtained by Bakri and Zhu for the standard Laplacian.


title: The shifted convolution of generalized divisor functions

abstract:
  We prove an asymptotic formula for the shifted convolution of the divisor
functions $d_k(n)$ and $d(n)$ with $k \geq 4$, which is uniform in the shift
parameter and which has a power-saving error term, improving results obtained
previously by Fouvry and Tenenbaum and, more recently, by Drappeau.


title:
Extended Transiting Disks and Rings Around Planets and Brown Dwarfs:
  Theoretical Constraints

abstract:
  Newly formed planets (or brown dwarfs) may possess disks or rings that occupy
an appreciable fraction of the planet's Hill sphere and extend beyond the
Laplace radius, where the tidal torque from the host star dominates over the
torque from the oblate planet. Such a disk/ring can exhibit unique, detectable
transit signatures, provided that the disk/ring is significantly misaligned
with the orbital plane of the planet. There exists tentative evidence for an
extended ring system around the young K5 star 1 SWASP J140747-354542. We
present a general theoretical study of the inclination (warp) profile of
circumplanetary disks under the combined influences of the tidal torque from
the central star, the torque from the oblate planet and the self-gravity of the
disk. We calculate the steady-state warp profile ("generalized Laplace
Surface") and investigate the condition for coherent precession of the disk. We
find that to maintain non-negligible misalignment between the extended outer
disk and the planet's orbital plane, and to ensure coherent disk precession,
the disk surface density must be sufficiently large so that the self-gravity
torque overcomes the tidal torque from the central star. Our analysis and
quantitative results can be used to constrain the parameters of transiting
circumplanetary disks that may be detected in the future.


title: A zonotope and a product of two simplices with disconnected flip graphs

abstract:
  We give an example of a three-dimensional zonotope whose set of tight
zonotopal tilings is not connected by flips. Using this, we show that the set
of triangulations of $\Delta^4 \times \Delta^n$ is not connected by flips for
large $n$. Our proof makes use of a non-explicit probabilistic construction.


title: Valence fluctuations in Sn(Pb)$_2$P$_2$S$_6$ ferroelectrics

abstract:
  The valence fluctuations which are related to the charge disproportionation
of phosphorous ions $P^{4+} + P^{4+}\rightarrow P^{3+} + P^{5+}$ are the origin
of ferroelectric and quantum paraelectric states in Sn(Pb)$_2$P$_2$S$_6$
semiconductors. They involve recharging of SnPS$_3$ or PbPS$_3$ structural
groups which could be represented as half-filled sites in the crystal lattice.
Temperature-pressure phase diagram for Sn$_2$P$_2$S$_6$ compound and
temperature-composition phase diagram for (Pb$_y$Sn$_{1-y}$)$_2$P$_2$S$_6$
mixed crystals, which include tricritical points and where a temperature of
phase transitions decrease to 0 K, together with the data about some softening
of low energy optic phonons and rise of dielectric susceptibility at cooling in
quantum paraelectric state of Pb$_2$P$_2$S$_6$, are analyzed by GGA electron
and phonon calculations and compared with electronic correlations models. The
anharmonic quantum oscillators model is developed for description of phase
diagrams and temperature dependence of dielectric susceptibility.


title:
Revisiting T2KK and T2KO physics potential and $\nu_\mu$ -
  $\bar{\nu}_\mu$ beam ratio

abstract:
  We revisit the sensitivity study of the Tokai-to-Kamioka-and-Korea (T2KK) and
Tokai-to-Kamioka-and-Oki (T2KO) proposals where a water Cerenkov detector with
the 100 kton fiducial volume is placed in Korea ($L = 1000$ km) and Oki island
($L = 653$ km) in Japan, respectively, in addition to the Super-Kamiokande for
determination of the neutrino mass hierarchy and leptonic CP phase
($\delta_{CP}$). We systematically study the running ratio of the $\nu_\mu$ and
$\bar{\nu}_\mu$ focusing beams with dedicated background estimation for the
$\nu_e$ appearance and $\nu_\mu$ disappearance signals, especially improving
treatment of the neutral current $\pi^0$ backgrounds. Using a $\nu_\mu$ -
$\bar{\nu}_\mu$ beam ratio between 3 : 2 and 2.5 : 2.5 (in unit of $10^{21}$POT
with the proton energy of 40 GeV), the mass hierarchy determination with the
median sensitivity of 3 - 5 $\sigma$ by the T2KK and 1 - 4 $\sigma$ by the T2KO
experiment are expected when $\sin^2\theta_{23} = 0.5$, depending on the mass
hierarchy pattern and CP phase. These sensitivities are enhanced (reduced) by
$30\%$ - $40\%$ in $\Delta \chi^2$ when $\sin^2\theta_{23} = 0.6\, (0.4)$. The
CP phase is measured with the uncertainty of $20^\circ$ - $50^\circ$ by the
T2KK and T2KO using the $\nu_\mu$ - $\bar{\nu}_\mu$ focusing beam ratio between
3.5 : 1.5 and 1.5 : 3.5. These findings indicate that inclusion of the
$\bar{\nu}_\mu$ focusing beam improves the sensitivities of the T2KK and T2KO
experiments to both the mass hierarchy determination and leptonic CP phase
measurement simultaneously with the preferred beam ratio being between 3 : 2 -
2.5 : 2.5 ($\times 10^{21}$POT).


title:
The $m=1$ instability \& gravitational wave signal in binary neutron
  star mergers

abstract:
  We examine the development and detectability of the $m=1$ instability in the
remnant of binary neutron star mergers. The detection of the gravitational mode
associated with the $m=1$ degree of freedom could potentially reveal details of
the equation of state. We analyze the post-merger epoch of simulations of both
equal and non-equal mass neutron star mergers using three realistic,
microphysical equations of state and neutrino cooling. Our studies show such an
instability develops generically and within a short dynamical time to strengths
that are comparable or stronger than the $m=2$ mode which is the strongest
during the early post-merger stage. We estimate the signal to noise ratio that
might be obtained for the $m=1$ mode and discuss the prospects for observing
this signal with available Earth-based detectors. Because the $m=1$ occurs at
roughly half the frequency of the more powerful $m=2$ signal and because it can
potentially be long-lived, targeted searches could be devised to observe it. We
estimate that with constant amplitude direct detection of the mode could occur
up to a distance of roughly $14\,\mathrm{Mpc}$ whereas a search triggered by
the inspiral signal could extend this distance to roughly $100\,\mathrm{Mpc}$.


title: Scattering theory of walking droplets in the presence of obstacles

abstract:
  We aim to describe a droplet bouncing on a vibrating bath using a simple and
highly versatile model inspired from quantum mechanics. Close to the Faraday
instability, a long-lived surface wave is created at each bounce, which serves
as a pilot wave for the droplet. This leads to so called walking droplets or
walkers. Since the seminal experiment by {\it Couder et al} [Phys. Rev. Lett.
{\bf 97}, 154101 (2006)] there have been many attempts to accurately reproduce
the experimental results. We propose to describe the trajectories of a walker
using a Green function approach. The Green function is related to the Helmholtz
equation with Neumann boundary conditions on the obstacle(s) and outgoing
boundary conditions at infinity. For a single-slit geometry our model is
exactly solvable and reproduces some general features observed experimentally.
It stands for a promising candidate to account for the presence of arbitrary
boundaries in the walker's dynamics.


title:
A dynamical quasiparticle approach for the Quark-Gluon-Plasma bulk and
  transport properties

abstract:
  The properties of quantum-chromo dynamics (QCD) nowadays are accessable by
lattice QCD calculations at vanishing quark chemical potential $\mu_q$=0 but
often lack a transparent physical interpretation. In this review we report
about results from an extended dynamical quasiparticle model (DQPM$^*$) in
which the effective parton propagators have a complex selfenergy that depends
on the temperature $T$ of the medium as well as on the chemical potential
$\mu_q$ and the parton three-momentum ${\boldsymbol p}$ with respect to the
medium at rest. It is demonstrated that this approach allows for a good
description of QCD thermodynamics with respect to the entropy density, pressure
etc. above the critical temperature $T_c \approx$ 158 MeV. Furthermore, the
quark susceptibility $\chi_q$ and the quark number density $n_q$ are found to
be reproduced simultaneously at zero and finite quark chemical potential. The
shear and bulk viscosities $\eta, \zeta$, and the electric conductivity
$\sigma_e$ from the DQPM$^*$ also turn out in close agreement with lattice
results for $\mu_q$ =0. The DQPM$^*$, furthermore, allows to evaluate the
momentum $p$, $T$ and $\mu_q$ dependencies of the partonic degrees of freedom
also for larger $\mu_q$ which are mandatory for transport studies of heavy-ion
collisions in the regime 5 GeV $< \sqrt{s_{NN}} <$ 10 GeV. We finally calculate
the charm quark diffusion coefficient $D_s$ -- evaluated from the differential
cross sections of partons in the medium for light and heavy quarks by employing
the propagators and couplings from the DQPM -- and compare to the available
lattice data. It is argued that the complete set of observables allows for a
transparent interpretation of the properties of hot QCD.


title: Active Learning for Community Detection in Stochastic Block Models

abstract:
  The stochastic block model (SBM) is an important generative model for random
graphs in network science and machine learning, useful for benchmarking
community detection (or clustering) algorithms. The symmetric SBM generates a
graph with $2n$ nodes which cluster into two equally sized communities. Nodes
connect with probability $p$ within a community and $q$ across different
communities. We consider the case of $p=a\ln (n)/n$ and $q=b\ln (n)/n$. In this
case, it was recently shown that recovering the community membership (or label)
of every node with high probability (w.h.p.) using only the graph is possible
if and only if the Chernoff-Hellinger (CH) divergence
$D(a,b)=(\sqrt{a}-\sqrt{b})^2 \geq 1$. In this work, we study if, and by how
much, community detection below the clustering threshold (i.e. $D(a,b)<1$) is
possible by querying the labels of a limited number of chosen nodes (i.e.,
active learning). Our main result is to show that, under certain conditions,
sampling the labels of a vanishingly small fraction of nodes (a number
sub-linear in $n$) is sufficient for exact community detection even when
$D(a,b)<1$. Furthermore, we provide an efficient learning algorithm which
recovers the community memberships of all nodes w.h.p. as long as the number of
sampled points meets the sufficient condition. We also show that recovery is
not possible if the number of observed labels is less than $n^{1-D(a,b)}$. The
validity of our results is demonstrated through numerical experiments.


title:
The Functional Integral formulation of the Schrieffer-Wolff
  transformation

abstract:
  We revisit the Schrieffer-Wolff transformation and present a path integral
version of this important canonical transformation. The equivalence between the
low-energy sector of the Anderson model in the so-called local moment regime
and the spin-isotropic Kondo model is usually established via a canonical
transformation performed on the Hamiltonian, followed by a projection. Here we
present a path integral formulation of the Schrieffer-Wolff transformation
which relates the functional integral form of the partition function of the
Anderson model to that of its effective low-energy model. The resulting
functional integral assumes the form of a spin path integral and includes a
geometric phase factor, i.e. a Berry phase. Our approach stresses the
underlying symmetries of the model and allows for a straightforward
generalization of the transformation to more involved models. It thus not only
sheds new light on a classic problem, it also offers a systematic route of
obtaining effective low-energy models and higher order corrections.


title:
Quenched tail estimate for the random walk in random scenery and in
  random layered conductance

abstract:
  We discuss the quenched tail estimates for the random walk in random scenery.
The random walk is the symmetric nearest neighbor walk and the random scenery
is assumed to be independent and identically distributed, non-negative, and has
a power law tail. We identify the long time aymptotics of the upper deviation
probability of the random walk in quenched random scenery, depending on the
tail of scenery distribution and the amount of the deviation. The result is in
turn applied to the tail estimates for a random walk in random conductance
which has a layered structure.


title:
Information Criteria for quantifying loss of reversibility in
  parallelized KMC

abstract:
  Parallel Kinetic Monte Carlo (KMC) is a potent tool to simulate stochastic
particle systems efficiently. However, despite literature on quantifying domain
decomposition errors of the particle system for this class of algorithms in the
short and in the long time regime, no study yet explores and quantifies the
loss of time-reversibility in Parallel KMC. Inspired by concepts from
non-equilibrium statistical mechanics, we propose the entropy production per
unit time, or entropy production rate, given in terms of an observable and a
corresponding estimator, as a metric that quantifies the loss of reversibility.
Typically, this is a quantity that cannot be computed explicitly for Parallel
KMC, which is why we develop a posteriori estimators that have good scaling
properties with respect to the size of the system. Through these estimators, we
can connect the different parameters of the scheme, such as the communication
time step of the parallelization, the choice of the domain decomposition, and
the computational schedule, with its performance in controlling the loss of
reversibility. From this point of view, the entropy production rate can be seen
both as an information criterion to compare the reversibility of different
parallel schemes and as a tool to diagnose reversibility issues with a
particular scheme. As a demonstration, we use Sandia Lab's SPPARKS software to
compare different parallelization schemes and different domain (lattice)
decompositions.


title: Regularization around a generic codimension one fold-fold singularity

abstract:
  This paper is devoted to study the generic fold-fold singularity of Filippov
systems on the plane, its unfoldings and its Sotomayor-Teixeira regularization.
We work with general Filippov systems and provide the bifurcation diagrams of
the fold-fold singularity and their unfoldings, proving that, under some
generic conditions, is a codimension one embedded submanifold of the set of all
Filippov systems. The regularization of this singularity is studied and its
bifurcation diagram is shown. In the visible-invisible case, the use of
geometric singular perturbation theory has been useful to give the complete
diagram of the unfolding, specially the appearance and disappearance of
periodic orbits that are not present in the Filippov vector field. In the case
of a linear regularization, we prove that the regularized system is equivalent
to a general slow-fast system studied by Krupa and Szmolyan [KrupaS01].


title:
Modeling of human society as a locally interacting product-potential
  networks of automaton

abstract:
  The central problems in social sciences concern the social and psychological
mechanisms and conditions required for the emergence and stability of human
groups. The present article is dedicated to the problem of stability of human
groups. We model human groups using local interacting systems of automaton with
relations and reactions and using the structural balance theory. The
'structural balance theory' ties the emergence of a human group with the human
actor's thoughts about how another actor treats him and his perception of
actors. The Cartwright and Harary formalization the concept of balance theory
within a graph theoretical setting unable to get a number of mathematical
results pertaining to an algebraic formulation of the theory of balance in
signed networks/graphs. The deeper generalization of 'balance theory' as the
smooth product-potential fields on domain gives us the ability to create theory
of 'smooth product potential social fields'. We then find that all discrete
product-potential system tightly connect with other process - process
multiplication on the randomly chosen matrices and we find connections between
stationary measures and some algebraic objects.


title:
The elephant in the room: The problem of quantifying productivity in
  evaluative scientometrics

abstract:
  In a critical and provocative paper, Abramo and D'Angelo claim that commonly
used scientometric indicators such as the mean normalized citation score (MNCS)
are completely inappropriate as indicators of scientific performance. Abramo
and D'Angelo argue that scientific performance should be quantified using
indicators that take into account the productivity of a research unit. We
provide a response to Abramo and D'Angelo, indicating where we believe they
raise important issues, but also pointing out where we believe their claims to
be too extreme.


title:
Schwinger pair creation in Dirac semimetals in the presence of external
  magnetic and electric fields

abstract:
  We discuss the Schwinger pair creation process for the system of massless
Dirac fermions in the presence of constant external magnetic and electric
fields. The pair production rate remains finite unlike the vacuum decay rate.
In the recently discovered Dirac semimetals, where the massless Dirac fermions
emerge, this pair production may be observed experimentally through the
transport properties. We estimate its contribution to the ordinary conductivity
of the semimetals.


title:
Dirac-Kondo semimetals and topological Kondo insulators in the dilute
  carrier limit

abstract:
  Heavy fermion systems contain not only strong electron correlations, which
promote a rich set of quantum phases, but also a large spin-orbit coupling,
which tends to endow the electronic states a topological character. Kondo
insulators are understood in terms of a lattice of local moments coupled to
conduction electrons in a half-filled band, i.e., with a dense population of
about one electron per unit cell. Here, we propose that a new class of Kondo
insulator arises when the conduction-electron band is nearly empty ( or,
equivalently, full ) . We demonstrated the effect through a honeycomb Anderson
lattice model. In the empty carrier limit, spin-orbit coupling produces a gap
in the hybridized heavy fermion band, thereby generating a topological Kondo
insulator. This state can be understood in terms of a nearby phase in the
overall phase diagram, a Dirac-Kondo semimetal whose quasiparticle excitations
exhibit a non-trivial Berry phase. Our results point to the dilute carrier
limit of the heavy-fermion systems as a new setting to study strongly
correlated insulating and topological states.


title:
Exchange bias-like effect in TbFeAl intermetallic induced by atomic
  disorder

abstract:
  Exchange bias-like effect observed in the intermetallic compound TbFeAl,
which displays a magnetic phase transition at $T^h_c \approx$ 198~K and a
second one at $T^l_c \approx$ 154~K, is reported. {\em Jump}-like features are
observed in the isothermal magnetization, $M (H)$, at 2~K which disappear above
8~K. The field-cooled magnetization isotherms below 10~K show loop-shifts that
are reminiscent of exchange bias, also supported by {\em training effect}.
Significant coercive field, $H_c \approx$ 1.5~T at 2~K is observed in TbFeAl
which, after an initial increase, shows subsequent decrease with temperature.
The exchange bias field, $H_{eb}$, shows a slight increase and subsequent
leveling off with temperature. It is argued that the inherent crystallographic
disorder among Fe and Al and the high magnetocrystalline anisotropy related to
Tb$^{3+}$ lead to the exchange bias effect. TbFeAl is recently reported to show
magnetocaloric effect and the present discovery of exchange bias makes this
compound a multifunctional one. The result obtained on TbFeAl generalizes the
observation of exchange bias in crystallographically disordered materials and
gives impetus for the search for materials with {\em exchange bias induced by
atomic disorder.}


title:
Categorification of Clifford algebra via geometric induction and
  restriction

abstract:
  We use geometric parabolic induction functors and the adjoint functors for
the supergroups Osp(2m+1,2n) (where m and n vary) to categorify the action of
the infinite-dimensional Clifford algebra on the Fock space of semi-infinite
forms.


title: Remarks on GJMS operator of order six

abstract:
  We study analysis aspects of the sixth order GJMS operator $P_g^6$. Under
conformal normal coordinates around a point, the expansions of Green's function
of $P_g^6$ with pole at this point are presented. As a starting point of the
study of $P_g^6$, we manage to give some existence results of prescribed
$Q$-curvature problem on Einstein manifolds. One among them is that for $n \geq
10$, let $(M^n,g)$ be a closed Einstein manifold of positive scalar curvature
and $f$ a smooth positive function in $M$. If the Weyl tensor is nonzero at a
maximum point of $f$ and $f$ satisfies a vanishing order condition at this
maximum point, then there exists a conformal metric $\tilde g$ of $g$ such that
its $Q$-curvature $Q_{\tilde g}^6$ equals $f$.


title:
The anisotropic oscillator on curved spaces: A new exactly solvable
  model

abstract:
  We present a new exactly solvable (classical and quantum) model that can be
interpreted as the generalization to the two-dimensional sphere and to the
hyperbolic space of the two-dimensional anisotropic oscillator with any pair of
frequencies $\omega_x$ and $\omega_y$. The new curved Hamiltonian ${H}_\kappa$
depends on the curvature $\kappa$ of the underlying space as a
deformation/contraction parameter, and the Liouville integrability of
${H}_\kappa$ relies on its separability in terms of geodesic parallel
coordinates, which generalize the Cartesian coordinates of the plane. Moreover,
the system is shown to be superintegrable for commensurate frequencies
$\omega_x: \omega_y$, thus mimicking the behaviour of the flat Euclidean case,
which is always recovered in the $\kappa\to 0$ limit. The additional constant
of motion in the commensurate case is, as expected, of higher-order in the
momenta and can be explicitly deduced by performing the classical factorization
of the Hamiltonian. The known $1:1$ and $2:1$ anisotropic curved oscillators
are recovered as particular cases of ${H}_\kappa$, meanwhile all the remaining
$\omega_x: \omega_y$ curved oscillators define new superintegrable systems.
Furthermore, the quantum Hamiltonian $\hat {H}_\kappa$ is fully constructed and
studied by following a quantum factorization approach. In the case of
commensurate frequencies, the Hamiltonian $\hat {H}_\kappa$ turns out to be
quantum superintegrable and leads to a new exactly solvable quantum model. Its
corresponding spectrum, that exhibits a maximal degeneracy, is explicitly given
as an analytical deformation of the Euclidean eigenvalues in terms of both the
curvature $\kappa$ and the Planck constant $\hbar$. In fact, such spectrum is
obtained as a composition of two one-dimensional (either trigonometric or
hyperbolic) P\"osch-Teller set of eigenvalues.


title:
Forbidden Iron Lines and Dust Destruction in Supernova Remnant Shocks:
  The Case of N49 in the Large Magellanic Cloud

abstract:
  We present results of a complete integral field survey of the bright SNR N49
in the LMC, obtained with the WiFeS instrument mounted on the ANU 2.3m
telescope at Siding Spring Observatory. From theoretical shock modelling with
the new MAPPINGS 5.1 code we have, for the first time, subjected the optical Fe
emission line spectrum of a supernova remnant to a detailed abundance and
dynamical analysis covering 8 separate stages of ionisation. This allows us to
derive the dust depletion factors as a function of ionisation stage. We have
shown that there is substantial (30% - 90%) destruction of Fe-bearing dust
grains in these fast shocks ($v_s \sim 250$ km/s), and we have confirmed that
the dominant dust destruction is through the non-thermal sputtering and
grain-grain collision mechanisms developed in a number of theoretical works.


title:
Estimates for the upscaling error in heterogeneous multiscale methods
  for wave propagation problems in locally periodic media

abstract:
  This paper concerns the analysis of a multiscale method for wave propagation
problems in microscopically nonhomogeneous media. A direct numerical
approximation of such problems is prohibitively expensive as it requires
resolving the microscopic variations over a much larger physical domain of
interest. The heterogeneous multiscale method (HMM) is an efficient framework
to approximate the solutions of multiscale problems. In HMM, one assumes an
incomplete macroscopic model which is coupled to a known but expensive
microscopic model. The micromodel is solved only locally to upscale the
parameter values which are missing in the macromodel. The resulting macroscopic
model can then be solved at a cost independent of the small scales in the
problem.
  In general, the accuracy of the HMM is related to how good the upscaling step
approximates the right macroscopic quantities. The analysis of the method, that
we consider here, was previously addressed only in purely periodic media
although the method itself is numerically shown to be applicable to more
general settings. In the present study, we consider a more realistic setting by
assuming a locally-periodic medium where slow and fast variations are allowed
at the same time. We then prove that HMM captures the right macroscopic
effects. The generality of the tools and ideas in the analysis allows us to
establish convergence rates in a multi-dimensional setting. The theoretical
findings here imply an improved convergence rate in one-dimension, which also
justifies the numerical observations from our earlier study.


title: Spheroidal groups, virtual cohomology and lower dimensional G-spaces

abstract:
  A space is defined to be "$n$-spheroidal" if it has the homotopy type of an
$n$-dimensional CW-complex $X$ with $H_{n}(X, \mathbb{Z})$ not zero and
finitely generated. A group $G$ is called "$n$-spheroidal" if its classifying
space $K(G,1)$ is $n$-spheroidal. Examples include fundamental groups of
compact manifold $K(G,1)$'s. Moreover, the class of groups $G$ which are
$n$-spheroidal for some $n$, is closed under products, free products, and group
extensions. If $Y$ is a space with $\pi_{1}(Y)$ $n$-spheroidal, and if
$H_{k}(Y;\mathbb{F}_{p})$ is non-zero and finitely generated, and if
$H_{i}(Y;\mathbb{F}_{p}) = 0$ for $i>k$, then
$H_{n+k}(\overline{Y};\mathbb{F}_{p}) \neq 0$ for $\overline{Y}$ a finite
sheeted covering space of $Y$. Hence, dim$(Y) \geq n+k$. Thus, it follows that
if dim$(Y) < n$, and if $H_{k}(Y;\mathbb{F}_{p}) \neq 0$ and
$H_{i}(Y;\mathbb{F}_{p}) = 0$ for $i>k>0$, then $H_{k}(Y;\mathbb{F}_{p})$ is
not finitely generated. Similar results follow for $Y\subset K(G,1)$.


title: Casimir Effect at finite temperature for the CPT-even extension of QED

abstract:
  By the thermofield dynamics (TFD) formalism we obtain the energy-momentum
tensor for the Electromagnetism with Lorentz Breaking Even term of the Standard
Model Extended (SME) Sector in a topology $S^{1}\times S^{1}\times R^{2}$. We
carry out the compactification by a generalized TFD-Bogoliubov transformation
that is used to define a renormalized energy-momentum tensor, and the Casimir
energy and pressure at finite temperature are then derived. A comparative
analysis with the electromagnetic case is developed, and we remark the
influence of the background in the traditional Casimir effect.


title: Tensor representations of $\mathfrak q(\infty)$

abstract:
  We introduce a symmetric monoidal category of modules over the direct limit
queer superalgebra $\q (\infty)$. The category can be defined in two equivalent
ways with the aid of the large annihilator condition. Tensor products of copies
of the natural and the conatural representations are injective objects in this
category. We obtain the socle filtrations and formulas for the tensor products
of the indecoposable injectives. In addition, it is proven that the category is
Koszul self-dual.


title:
Learning Concepts First: A Course Structure with Improved Educational
  Outcomes in the Short, Medium, and Long Terms (Especially for Minority Groups
  Underrepresented in Physics)

abstract:
  An active learning physics course (treatment) was re-organized in an attempt
to increase students' problem solving abilities. This re-organized course
covered all of the relevant concepts in the first 6 weeks with the final 4
weeks spent in practice at solving complicated problems (those requiring
students to use higher order cognitive abilities). A second active learning
course (control) was taught in the same quarter by the same instructor using
the same curricular materials but covering material in the standard
(chapter-by-chapter) order. After accounting for incoming student
characteristics, students from the treatment course scored significantly better
than the control for two outcome measures: i) the final exam and ii) their
immediately subsequent physics course. More importantly, students from minority
groups who are underrepresented in physics had final exam scores as well as
class grades that were indistinguishable from the rest of their class if and
only if they were in the treatment class. Finally, many of the students in this
cohort took a Concepts First course in their third quarter of introductory
physics. The students who took at least one Concepts First course are found to
have significantly higher rates of graduation with a STEM major than those
students from this cohort who did not take a Concepts First course.


title: The "Parity" Anomaly On An Unorientable Manifold

abstract:
  The "parity" anomaly -- more accurately described as an anomaly in
time-reversal or reflection symmetry -- arises in certain theories of fermions
coupled to gauge fields and/or gravity in a spacetime of odd dimension. This
anomaly has traditionally been studied on orientable manifolds only, but recent
developments involving topological superconductors have made it clear that one
can get more information by asking what happens on an unorientable manifold. In
this paper, we give a full description of the "parity" anomaly for fermions
coupled to gauge fields and gravity in $2+1$ dimensions on a possibly
unorientable spacetime. We consider an application to topological
superconductors and another application to M-theory. The application to
topological superconductors involves using knowledge of the "parity" anomaly as
an ingredient in constructing gapped boundary states of these systems and in
particular in gapping the boundary of a $\nu=16$ system in a topologically
trivial fashion. The application to M-theory involves showing the consistency
of the path integral of an M-theory membrane on a possibly unorientable
worldvolume. In the past, this has been done only in the orientable case.


title: The quantum origins of moment fragmentation in Nd2Zr2O7

abstract:
  Spin-liquid states are often described as the antithesis of magnetic order.
Recently, however, it has been proposed that in certain frustrated magnets the
magnetic degrees of freedom may "fragment" in such a way as to give rise to a
coexistence of spin liquid and ordered phases. Recent neutron-scattering
results [S. Petit, E. Lhotel, B. Canals, M. Ciomaga Hatnean, J. Ollivier, H.
Muttka, E. Ressouche, A. R. Wildes, M. R. Lees, and G. Balakrishnan, Nat. Phys.
12, 746 (2016)] suggest that this scenario may be realized in the pyrochlore
magnet Nd2Zr2O7. These observations show the characteristic pinch-point
features of a Coulombic spin liquid occurring alongside the Bragg peaks of an
"all-in-all-out" ordered state. Here we explain the quantum origins of this
apparent magnetic moment fragmentation, within the framework of a quantum model
of nearest-neighbor exchange, appropriate to Nd2Zr2O7. This model is able to
capture both the ground-state order and the pinch points observed at finite
energy. The observed fragmentation arises due to the combination of the unusual
symmetry properties of the Nd3+ ionic wave functions and the structure of
equations of motion of the magnetic degrees of freedom. The results of our
analysis suggest that Nd2Zr2O7 is proximate to a U(1) spin-liquid phase and is
a promising candidate for the observation of a Higgs transition in a magnetic
system.


title: Energy Efficiency in Wireless Sensor Networks

abstract:
  Unlike most of the current research that focuses on a single aspect of WSNs,
we present an Energy Driven Architecture (EDA) as a new architecture for
minimising the total energy consumption of WSNs. EDA as a constituent-based
architecture is used to deploy WSNs according to energy dissipation through
their constituents. This view of overall energy consumption in WSNs can be
applied to optimising and balancing energy consumption and increasing the
network lifetime. Refer back to the architecture, we introduce a single overall
model and propose a feasible formulation to express the overall energy
consumption of a generic wireless sensor network application in terms of its
energy constituents. The formulation offers a concrete expression for
evaluating the performance of WSN application, optimising its constituents
operations, and designing more energy-efficient applications. The ultimate aim
is to produce an energy map architecture of a generic WSN application that
comprises essential and definable energy constituents and the relationships
between these constituents to explore strategies for minimising the overall
energy consumption of the application. Later, parameters affecting energy in
WSNs are extracted. The dependency between these parameters and the average
energy consumption of an application is then investigated. A few statistical
tools are applied for parameter reduction followed by random forest regression
to model energy consumption per delivered packet with and without parameter
reduction to determine the reduction in accuracy due to reduction. Finally, an
energy-efficient dynamic topology management algorithm is proposed based on the
EDA model and the prevalent parameters. The performance of the new topology
management algorithm, which employs Dijkstra to find energy-efficient lowest
cost paths among nodes, is compared to similar topology management algorithms.


title:
Hamiltonian structure for two-dimensional extended Green-Naghdi
  equations

abstract:
  The two-dimensional Green-Naghdi (GN) shallow-water model for surface gravity
waves is extended to incorporate the arbitrary higher-order dispersive effects.
This can be achieved by developing a novel asymptotic analysis applied to the
basic nonlinear water wave problem. The linear dispersion relation for the
extended GN system is then explored in detail. In particular, we use its
characteristics to discuss the well-posedness of the linearized problem. As
illustrative examples of approximate model equations, we derive a higher-order
model that is accurate to the fourth power of the dispersion parameter in the
case of a flat bottom topography, and address the related issues such as the
linear dispersion relation, conservation laws and the pressure distribution at
the fluid bottom on the basis of this model. The original GN model is then
briefly described in the case of an uneven bottom topography. Subsequently, the
extended GN system presented here is shown to have the same Hamiltonian
structure as that of the original GN system. Last, we demonstrate that
Zakharov's Hamiltonian formulation of surface gravity waves is equivalent to
that of the extended GN system by rewriting the former system in terms of the
momentum density instead of the velocity potential at the free surface.


title: Development and test of a real-size MRPC for CBM-TOF

abstract:
  In the CBM (Compressed Baryonic Matter) experiment constructed at the
Facility for Anti-proton and Ion Research (Fair) at GSI, Darmstadt, Germany,
MRPC(Multi-gap Resistive Plate Chamber) is adopted to construct the large TOF
(Time-of-Flight) system to achieve an unprecedented precision of hadron
identification, benefiting from its good time resolution, relatively high
efficiency and low building price. We have developed a kind of double-ended
readout strip MRPC. It uses low resistive glass to keep good performance of
time resolution under high-rate condition. The differential double stack
structure of 2x4 gas gaps help to reduce the required high voltage to half.
There are 24 strips on one counter, and each is 270mm long, 7mm wide and the
interval is 3mm. Ground is placed onto the MRPC electrode and feed through is
carefully designed to match the 100 Ohm impedance of PADI electronics. The
prototype of this strip MRPC has been tested with cosmic ray, a 98% efficiency
and 60ps time resolution is gotten. In order to further examine the performance
of the detector working under higher particle flux rate, the prototype has been
tested in the 2014 October GSI beam time and 2015 February CERN beam time. In
both beam times a relatively high rate of 1 kHz/cm2 was obtained. The
calibration is done with CBM ROOT. A couple of corrections has been considered
in the calibration and analysis process (including time-walk correction, gain
correction, strip alignment correction and velocity correction) to access
actual counter performances such as efficiency and time resolution. An
efficiency of 97% and time resolution of 48ps are obtained. All these results
show that the real-size prototype is fully capable of the requirement of the
CBM-TOF, and new designs such as self-sealing are modified into the strip
counter prototype to obtain even better performance.


title:
Properties of a rare-earth-ion-doped waveguide at sub-Kelvin
  temperatures for quantum signal processing

abstract:
  We characterize the 795 nm $^3$H$_6$ to $^3$H$_4$ transition of Tm$^{3+}$ in
a Ti$^{4+}$:LiNbO$_{3}$ waveguide at temperatures as low as 800 mK. Coherence
and hyperfine population lifetimes -- up to 117 $\mu$s and 2.5 hours,
respectively -- exceed those at 3 K at least ten-fold, and are equivalent to
those observed in a bulk Tm$^{3+}$:LiNbO$_{3}$ crystal under similar
conditions. We also find a transition dipole moment that is equivalent to that
of the bulk. Finally, we prepare a 0.5 GHz-bandwidth atomic frequency comb of
finesse $>$2 on a vanishing background. These results demonstrate the
suitability of rare-earth-doped waveguides created using industry-standard
Ti-indiffusion in LiNbO$_3$ for on-chip quantum applications.


title:
Time-dependent Ginzburg-Landau equation and Boltzmann transport equation
  for charge-density-wave conductors

abstract:
  The time-dependent Ginzburg-Landau equation and the Boltzmann transport
equation for one-dimensional charge-density-wave (CDW) conductors are derived
from a microscopic model by applying the Keldysh Green's function approach
under a quasiclassical approximation. The effects of external electric field
and impurity pinning of the CDW are fully taken into account without relying on
a phenomenological argument. These equations simultaneously describe
spatiotemporal dynamics of both the CDW and quasiparticles, so they serve as a
powerful tool to analyze various nonequilibrium phenomena, such as the current
conversion between the CDW condensate and quasiparticles mediated by phase
slips. It is shown that, in typical situations, the equations correctly
describe the nonlinear behavior of electric conductivity in a simpler manner.


title: Irregular primes to two billion

abstract:
  We compute all irregular primes less than 2^31 = 2 147 483 648. We verify the
Kummer-Vandiver conjecture for each of these primes, and we check that the
p-part of the class group of Q(zeta_p) has the simplest possible structure
consistent with the index of irregularity of p. Our method for computing the
irregular indices saves a constant factor in time relative to previous methods,
by adapting Rader's algorithm for evaluating discrete Fourier transforms.


title:
Impacts of the tensor couplings of $\omega$ and $\rho$ mesons and
  Coulomb exchange terms on super-heavy nuclei and their relation to symmetry
  energy

abstract:
  We have studied the effects of tensor coupling of $\omega$ and $\rho$ meson
terms, Coulomb exchange term in local density approximation and various
isoscalar-isovector coupling terms of relativistic mean field model on the
properties of nuclear matter, finite nuclei, and super-heavy nuclei. We found
that for the same fixed value of symmetry energy $J$ or its slope $L$ the
presence of tensor coupling of $\omega$ and $\rho$ meson terms and Coulomb
exchange term yields thicker neutron skin thickness of $^{208}$Pb. We also
found that the roles of tensor coupling of $\omega$ and $\rho$ meson terms,
Coulomb exchange term in local density approximation and various
isoscalar-isovector coupling terms on the bulk properties of finite nuclei
varies depending on the corresponding nucleus mass. However, on average, tensor
coupling terms play a significant role in predicting the bulk properties of
finite nuclei in a quite wide mass range especially in binding energies. We
also observed that for some particular nuclei, the corresponding experimental
data of binding energies is rather less compatible with the presence of Coulomb
exchange term in local density approximation and they tend to disfavor the
presence of isoscalar-isovector coupling term with too high $\Lambda$ value.
Furthermore, we have found that these terms influence the detail properties of
$^{292}$120 super-heavy nucleus such as binding energies, the magnitude of two
nucleon gaps, single particle spectra, neutron densities, neutron skin
thicknesses and mean square charge radii. However, the shell closure
predictions of $^{208}$Pb and $^{292}$120 nuclei is not affected by the
presence of these terms.


title: Fast Escape in Incompressible Vector Fields

abstract:
  Swimmers caught in a rip current flowing away from the shore are advised to
swim orthogonally to the current to escape it. We describe a mathematical
principle in a similar spirit. More precisely, we consider flows $\gamma$ in
the plane induced by incompressible vector fields $\textbf{v}:\mathbb{R}^2
\rightarrow \mathbb{R}^2$ satisfying $ c_1 < \|v\| < c_2.$ The length $\ell$ a
flow curve $\dot \gamma(t) = \textbf{v}(\gamma(t))$ until $\gamma$ leaves a
disk of radius 1 centered at the initial position can be as long as $\ell \sim
c_2/c_1$. The same is true for the orthogonal flow $\textbf{v}^{\perp} =
(-\textbf{v}_2, \textbf{v}_1)$. We show that a combination does strictly
better: there always exists a curve flowing first along $\textbf{v}^{\perp}$
and then along $\textbf{v}$ which escapes the unit disk before reaching the
length $ \sqrt{4\pi c_2 / c_1}$. Moreover, if the escape length of $\textbf{v}$
is uniformly $\sim c_2/c_1$, then the escape length of $\textbf{v}^{\perp}$ is
uniformly $\sim 1$ (allowing for a fast escape from the current). We also prove
an elementary quantitative Poincar\'{e}-Bendixson theorem that seems to be new.


title: Audio Event Detection using Weakly Labeled Data

abstract:
  Acoustic event detection is essential for content analysis and description of
multimedia recordings. The majority of current literature on the topic learns
the detectors through fully-supervised techniques employing strongly labeled
data. However, the labels available for majority of multimedia data are
generally weak and do not provide sufficient detail for such methods to be
employed. In this paper we propose a framework for learning acoustic event
detectors using only weakly labeled data. We first show that audio event
detection using weak labels can be formulated as an Multiple Instance Learning
problem. We then suggest two frameworks for solving multiple-instance learning,
one based on support vector machines, and the other on neural networks. The
proposed methods can help in removing the time consuming and expensive process
of manually annotating data to facilitate fully supervised learning. Moreover,
it can not only detect events in a recording but can also provide temporal
locations of events in the recording. This helps in obtaining a complete
description of the recording and is notable since temporal information was
never known in the first place in weakly labeled data.


title:
Game-theoretic Demand-side Management Robust to Non-Ideal Consumer
  Behavior in Smart Grid

abstract:
  This paper investigates effects of realistic, non-ideal, decisions of energy
users as to whether to participate in an energy trading system proposed for
demand-side management of a residential community. The energy trading system
adopts a non-cooperative Stackelberg game between a community energy storage
(CES) device and users with rooftop photovoltaic panels where the CES operator
is the leader and the users are the followers. Participating users determine
their optimal energy trading starting time to minimize their personal daily
energy costs while subjectively viewing their opponents' actions. Following a
non-cooperative game, we study the subjective behavior of users when they
decide on energy trading starting time using prospect theory. We show that
depending on the decisions of participating-time, the proposed energy trading
system has a unique Stackelberg equilibrium at which the CES operator maximizes
their revenue while users minimize their personal energy costs attaining a Nash
equilibrium. Simulation results confirm that the benefits of the energy trading
system are robust to decisions of participating-time that significantly deviate
from complete rationality.


title:
Probing the Neutrino Mass through the Cross Correlation between the
  Rees-Sciama Effect and Weak Lensing

abstract:
  Cosmology plays a fundamental role to determine the neutrino mass, therefore
also to determine its mass hierarchy, since the massive neutrino contributes to
the total matter density in the Universe at the background and perturbation
levels, once it becomes non-relativistic. After the non-relativistic transition
the fluctuations are smashed out at the scales $k\gg k_{fs}$. Therefore, the
missing fluctuation in the total matter is imprinted on the large scale
structure, say the suppression of the matter power spectrum $\Delta P/P\approx
-8f_{\nu}$ at the scales $k\gg k_{fs}$. In this paper, instead of considering
the linear perturbation theory, which is well understood in the presence of
neutrino, we propose to use the cross correlation between the Rees-Sciama
effect and weak lensing to probe the neutrino mass. At the small scales, the
density contrast grows faster than the background scale factor $\delta\sim a$,
that makes a sign flipping on $\Phi' \propto \mathcal{H}\delta d\ln
(\delta/a)/d\ln a$, which happens only in the non-linear regime. We show that
the flipping scale in the cross power spectrum between the Rees-Sciama effect
and weak lensing depends on the neutrino mass by assuming the shallow and deep
weak lensing surveys. Our analysis shows that the Deep survey has larger
signal-to-noise ratio $S/N\sim 160$. Finally, we use the Fisher information
matrix to forecast constraint on the neutrino mass.


title: Electronic structure of FeSe monolayer superconductors

abstract:
  We review a variety of theoretical and experimental results concerning
electronic band structure of superconducting materials based on FeSe
monolayers. Three type of systems are analyzed: intercalated FeSe systems
A_xFe_2Se_{2-x}S_x and [Li_{1-x}Fe_xOH]FeSe as well as the single FeSe layer
films on SrTiO_3 substrate. We present the results of detailed first principle
electronic band structure calculations for these systems together with
comparison with some experimental ARPES data. The electronic structure of these
systems is rather different from that of typical FeAs superconductors, which is
quite significant for possible microscopic mechanism of superconductivity. This
is reflected in the absence of hole pockets of the Fermi surface at
\Gamma-point in Brillouin zone, so that there are no "nesting" properties of
different Fermi surface pockets. LDA+DMFT calculations show that correlation
effects on Fe-3d states in the single FeSe layer are not that strong as in most
of FeAs systems. As a result, at present there is no theoretical understanding
of the formation of rather "shallow" electronic bands at M points. LDA
calculations show that the main difference in electronic structure of FeSe
monolayer on SrTiO_3 substrate from isolated FeSe layer is the presence of the
band of O-2p surface states of TiO_2 layer on the Fermi level together with
Fe-3d states, which may be important for understanding the enhanced T_c values
in this system. We briefly discuss the implications of our results for
microscopic models of superconductivity.


title: Low-end mass function of the Quintuplet cluster

abstract:
  The Quintuplet and Arches clusters, which were formed in the harsh
environment of the Galactic Center (GC) a few million years ago, have been
excellent targets for studying the effects of a star-forming environment on the
initial mass function (IMF). In order to estimate the shape of the low-end IMF
of the Arches cluster, Shin & Kim devised a novel photometric method that
utilizes pixel intensity histograms (PIHs) of the observed images. Here, we
apply the PIH method to the Quintuplet cluster and estimate the shape of its
low-end IMF below the magnitude of completeness limit as set by conventional
photometry. We found that the low-end IMF of the Quintuplet is consistent with
that found for the Arches cluster--Kroupa MF, with a significant number of
low-mass stars below 1 $M_{\odot}$. We conclude that the most likely IMFs of
the Quintuplet and the Arches clusters are not too different from the IMFs
found in the Galactic disc. We also find that the observed PIHs and stellar
number density profiles of both clusters are best reproduced when the clusters
are assumed to be at three-dimensional distances of approximately 100 pc from
the GC.


title:
A Random Finite Set Approach for Dynamic Occupancy Grid Maps with
  Real-Time Application

abstract:
  Grid mapping is a well established approach for environment perception in
robotic and automotive applications. Early work suggests estimating the
occupancy state of each grid cell in a robot's environment using a Bayesian
filter to recursively combine new measurements with the current posterior state
estimate of each grid cell. This filter is often referred to as binary Bayes
filter (BBF). A basic assumption of classical occupancy grid maps is a
stationary environment. Recent publications describe bottom-up approaches using
particles to represent the dynamic state of a grid cell and outline
prediction-update recursions in a heuristic manner. This paper defines the
state of multiple grid cells as a random finite set, which allows to model the
environment as a stochastic, dynamic system with multiple obstacles, observed
by a stochastic measurement system. It motivates an original filter called the
probability hypothesis density / multi-instance Bernoulli (PHD/MIB) filter in a
top-down manner. The paper presents a real-time application serving as a fusion
layer for laser and radar sensor data and describes in detail a highly
efficient parallel particle filter implementation. A quantitative evaluation
shows that parameters of the stochastic process model affect the filter results
as theoretically expected and that appropriate process and observation models
provide consistent state estimation results.


title:
Production of $Y(4260)$ as a hadronic molecule state of $\bar{D}D_1
  +c.c.$ in $e^+e^-$ annihilations

abstract:
  We study the $Y(4260)$ production mechanism in $e^+e^-$ annihilations in the
framework of hadronic molecules and investigate the consequence of such a
picture in different decay channels. In the hadronic molecule picture the
$Y(4260)$ is described as a mixture state composed of a long-ranged
$\bar{D}D_1(2420)+c.c.$ molecule state and a compact $c\bar{c}$ component. We
show that the compositeness relation can still provide a reasonable constraint
on the wavefunction renormalization parameter due to the dominance of the
molecular component. Such a mechanism can be regarded as a natural consequence
of the heavy quark spin symmetry (HQSS) breaking. This study elaborates the
molecular picture for the $Y(4260)$ in the $e^+e^-$ annihilations and affirms
that the cross section lineshape of $e^+e^-\to \bar{D}D^*\pi+c.c.$ in the
vicinity of the $Y(4260)$ should have a nontrivial behavior. In this framework
we predict that the upper limit of the $Y(4260)$ leptonic decay width is about
500 eV. We also investigate the coupling for $D_1(2420)\to D^*\pi$ in the
$^3P_0$ quark model and examine the possible HQSS breaking effects due to the
deviation from the $|^1P_1\rangle$ and $|^3P_1\rangle$ ideal mixing. This will
in turn provide a constraint on the HQSS breaking coupling for the $Y(4260)$ to
$\bar{D}D_1(2420)+c.c.$ via its $c\bar{c}$ component.


title:
Structured Nonconvex and Nonsmooth Optimization: Algorithms and
  Iteration Complexity Analysis

abstract:
  Nonconvex and nonsmooth optimization problems are frequently encountered in
much of statistics, business, science and engineering, but they are not yet
widely recognized as a technology in the sense of scalability. A reason for
this relatively low degree of popularity is the lack of a well developed system
of theory and algorithms to support the applications, as is the case for its
convex counterpart. This paper aims to take one step in the direction of
disciplined nonconvex and nonsmooth optimization. In particular, we consider in
this paper some constrained nonconvex optimization models in block decision
variables, with or without coupled affine constraints. In the case of without
coupled constraints, we show a sublinear rate of convergence to an
$\epsilon$-stationary solution in the form of variational inequality for a
generalized conditional gradient method, where the convergence rate is shown to
be dependent on the H\"olderian continuity of the gradient of the smooth part
of the objective. For the model with coupled affine constraints, we introduce
corresponding $\epsilon$-stationarity conditions, and apply two proximal-type
variants of the ADMM to solve such a model, assuming the proximal ADMM updates
can be implemented for all the block variables except for the last block, for
which either a gradient step or a majorization-minimization step is
implemented. We show an iteration complexity bound of $O(1/\epsilon^2)$ to
reach an $\epsilon$-stationary solution for both algorithms. Moreover, we show
that the same iteration complexity of a proximal BCD method follows
immediately. Numerical results are provided to illustrate the efficacy of the
proposed algorithms for tensor robust PCA.


title:
Ionospheric Modelling using GPS to Calibrate the MWA. II: Regional
  ionospheric modelling using GPS and GLONASS to estimate ionospheric gradients

abstract:
  We estimate spatial gradients in the ionosphere using the Global Positioning
System (GPS) and GLONASS (Russian global navigation system) observations,
utilising data from multiple GPS stations in the vicinity of Murchison
Radio-astronomy Observatory (MRO). In previous work the ionosphere was
characterised using a single-station to model the ionosphere as a single layer
of fixed height and this was compared with ionospheric data derived from radio
astronomy observations obtained from the Murchison Widefield Array (MWA).
Having made improvements to our data quality (via cycle slip detection and
repair) and incorporating data from the GLONASS system, we now present a
multi-station approach. These two developments significantly improve our
modelling of the ionosphere. We also explore the effects of a variable-height
model. We conclude that modelling the small-scale features in the ionosphere
that have been observed with the MWA will require a much denser network of
Global Navigation Satellite System (GNSS) stations than is currently available
at the MRO.


title: Distance verification for LDPC codes

abstract:
  The problem of finding code distance has been long studied for the generic
ensembles of linear codes and led to several algorithms that substantially
reduce exponential complexity of this task. However, no asymptotic complexity
bounds are known for distance verification in other ensembles of linear codes.
Our goal is to re-design the existing generic algorithms of distance
verification and derive their complexity for LDPC codes. We obtain new
complexity bounds with provable performance expressed in terms of the
erasure-correcting thresholds of long LDPC codes. These bounds exponentially
reduce complexity estimates known for linear codes.


title:
Convergence Analysis of Classes of Asymmetric Networks of Cucker-Smale
  Type with Deterministic Perturbations

abstract:
  We introduce and discuss two nonlinear perturbed extensions of the
Cucker-Smale model with asymmetric coupling weights. The first model assumes a
finite collection of autonomous agents aiming to perform a consensus process in
the presence of identical internal dynamics. The second model describes a
similar population of agents that perform velocity alignment with the
restriction of collision-free orbits. Although qualitatively different, we
explain how these two non-trivial types of perturbations are analyzed under a
unified framework. Rigorous analysis is conducted towards establishing new
sufficient conditions for asymptotic flocking to a synchronized motion.
Applications of our results are compared with simulations to illustrate the
effectiveness of our theoretical estimates.


title:
The Cauchy problem for higher-order modified Camassa-Holm equations on
  the circle

abstract:
  In this paper, we investigate the Cauchy problem for the shallow water type
equation \begin{eqnarray*} u_{t}+\partial_{x}^{2j+1}u +
\frac{1}{2}\partial_{x}(u^{2})+
\partial_{x}(1-\partial_{x}^{2})^{-1}\left[u^{2}+\frac{1}{2}u_{x}^{2}\right]=0
\end{eqnarray*} with low regularity data in the periodic settings. Himonas and
Misiolek (Communications in Partial Differential Equations, 23(1998), 123-139.)
have proved that the problem is locally well-posed for small initial data in
H^{s}(\mathbf{T}) with s\geq-\frac{j}{2}+1,j\in N^{+} with the aid of the
standard Fourier restriction norm method. To the best of our knowledge, there
is no result of well-posedness about the problem when s<-\frac{j}{2}+1.
  In this paper, firstly, we prove that the bilinear estimate related to the
nonlinear term of the equation in standard Bourgain space is invalid with
s<-\frac{j}{2}+1.
  Then we prove that the Cauchy problem for the periodic shallow water-type
equation is locally well-posed in H^{s}(\mathbf{T}) with -j+\frac{3}{2}<
s<-\frac{j}{2}+1,j\geq2 for arbitrary initial data.
  The novelty is that we introduce some new function spaces and give a useful
relationship among new spaces.


title: Flow equation for the large $N$ scalar model and induced geometries

abstract:
  We study the proposal that a $d+1$ dimensional induced metric is constructed
from a $d$ dimensional field theory using gradient flow. Applying the idea to
the O($N$) $\varphi^4$ model and normalizing the flow field, we have shown in
the large $N$ limit that the induced metric is finite and universal in the
sense that it does not depend on the details of the flow equation and the
original field theory except for the renormalized mass, which is the only
relevant quantity in this limit. We have found that the induced metric
describes Euclidean Anti-de-Sitter (AdS) space in both ultra-violet (UV) and
infra-red (IR) limits of the flow direction, where the radius of the AdS is
bigger in the IR than in the UV.


title: Minors of asymptotically almost all sparse paving matroids

abstract:
  We use counting arguments to show that asymptotically almost all sparse
paving matroids contain an $H$-minor, where $H$ falls into one of several
simple classes of matroids. Furthermore the result holds for all $H$ in a
larger class of matroids, if we restrict to asymptotically almost all sparse
paving matroids of fixed rank $r$ (where $r$ is necessarily no smaller than the
rank of $H$).


title: A Note on the Structure of Roller Coaster Permutations

abstract:
  We consider the structure of roller coaster permutations as introduced by
Ahmed & Snevily[1]. A roller coaster permutation is described as a permuta-
tion that maximizes the total switches from ascending to descending or visa
versa for the permutation and all of its subpermutations simultaneously. This
paper looks at the alternating structure of these permutations and then we
introduce a notion of a condition stronger than alternating for a permutation
that we shall refer to as recursively alternating. We also examine the behav-
ior of what entries can show up in even, odd, and end positions within the
permutations.


title:
Poisson statistics for 1d Schr\"odinger operators with random decaying
  potentials

abstract:
  We consider the 1d Schr\"odinger operators with random decaying potentials
where the spectrum is pure point(sub-critical case). We show that the point
process composed of the rescaled eivenvalues, together with those zero points
of the corresponding eigenfunctions, converges to the Poisson process.


title:
Effects of vibrational anharmonicity on molecular electronic conduction
  and thermoelectric efficiency

abstract:
  We study inelastic vibration-assisted charge transfer effects in two-site
molecular junctions, focusing on signatures of vibrational anharmonicity on the
electrical characteristics and the thermoelectric response of the junction. We
consider three types of oscillators: harmonic, anharmonic-Morse allowing bond
dissociation, and harmonic-quartic, mimicking a confinement potential. Using a
quantum master equation method which is perturbative in the electron-vibration
interaction we find that the (inelastic) electrical and thermal conductances
can be largely affected by the nature of the vibrational potential. In
contrast, the Seebeck coefficient, the thermoelectric figure-of-merit, and the
thermoelectric efficiency beyond linear response, conceal this information,
showing a rather weak sensitivity to vibrational anharmonicity. Our work
illustrates that anharmonic (many-body) effects, consequential to the
current-voltage characteristics, are of little effect for the thermoelectric
performance.


title:
Mean-correction and Higher Order Moments for a Stochastic Volatility
  Model with Correlated Errors

abstract:
  In an efficient stock market, the log-returns and their time-dependent
variances are often jointly modelled by stochastic volatility models (SVMs).
Many SVMs assume that errors in log-return and latent volatility process are
uncorrelated, which is unrealistic. It turns out that if a non-zero correlation
is included in the SVM (e.g., Shephard (2005)), then the expected log-return at
time t conditional on the past returns is non-zero, which is not a desirable
feature of an efficient stock market. In this paper, we propose a
mean-correction for such an SVM for discrete-time returns with non-zero
correlation. We also find closed form analytical expressions for higher moments
of log-return and its lead-lag correlations with the volatility process. We
compare the performance of the proposed and classical SVMs on S&P 500 index
returns obtained from NYSE.


title: Can you take Toernquist's inaccessible away?

abstract: We prove that ZF+DC+"There are no mad families" is equiconsistent with ZFC.


title: What can the occult do for you?

abstract:
  Interstellar dust is still a dominant uncertainty in Astronomy, limiting
precision in e.g., cosmological distance estimates and models of how light is
re-processed within a galaxy. When a foreground galaxy serendipitously overlaps
a more distant one, the latter backlights the dusty structures in the nearer
foreground galaxy. Such an overlapping or occulting galaxy pair can be used to
measure the distribution of dust in the closest galaxy with great accuracy. The
STARSMOG program uses Hubble to map the distribution of dust in foreground
galaxies in fine (<100 pc) detail. Integral Field Unit (IFU) observations will
map the effective extinction curve, disentangling the role of fine-scale
geometry and grain composition on the path of light through a galaxy. The
overlapping galaxy technique promises to deliver a clear understanding of the
dust in galaxies: geometry, a probability function of dimming as a function of
galaxy mass and radius, and its dependence on wavelength.


title: Nash twist and Gaussian noise measure on isometric $C^1$ maps

abstract:
  Starting with a short map $f_0:I\to \mathbb R^3$ on the unit interval $I$, we
construct random isometric map $f_n:I\to \mathbb R^3$ (with respect to some
fixed Riemannian metrics) for each positive integer $n$, such that the
difference $(f_n - f_0)$ goes to zero in the $C^0$ norm. The construction of
$f_n$ uses the Nash twist. We show that the distribution of $ n^{1/2} (f_n -
f_0)$ converges (weakly) to a Gaussian noise measure.


title:
Two-dimensional Halide Perovskites: Tuning Electronic Activities of
  Defects

abstract:
  Two-dimensional (2D) halide perovskites are emerging as promising candidates
for nano-electronics and optoelectronics. To realize their full potential, it
is important to understand the role of those defects that can strongly impact
material properties. In contrast to other popular 2D semiconductors (e.g.
transition metal dichalcogenides MX2) for which defects typically induce
harmful traps, we show that the electronic activities of defects in 2D
perovskites are significantly tunable. For example, even with a fixed lattice
orientation, one can change the synthesis conditions to convert a line defect
(edge or grain boundary) from electron acceptor to inactive site without deep
gap states. We show that this difference originates from the enhanced ionic
bonding in these perovskites compared with MX2. The donors tend to have high
formation energies, and the harmful defects are difficult to form at a low
halide chemical potential. Thus we unveil unique properties of defects in 2D
perovskites and suggest practical routes to improve them.


title: On Deep Holes of Projective Reed-Solomon Codes

abstract:
  In this paper, we obtain new results on the covering radius and deep holes
for projective Reed-Solomon (PRS) codes.


title: Learning Discriminative Features with Class Encoder

abstract:
  Deep neural networks usually benefit from unsupervised pre-training, e.g.
auto-encoders. However, the classifier further needs supervised fine-tuning
methods for good discrimination. Besides, due to the limits of full-connection,
the application of auto-encoders is usually limited to small, well aligned
images. In this paper, we incorporate the supervised information to propose a
novel formulation, namely class-encoder, whose training objective is to
reconstruct a sample from another one of which the labels are identical.
Class-encoder aims to minimize the intra-class variations in the feature space,
and to learn a good discriminative manifolds on a class scale. We impose the
class-encoder as a constraint into the softmax for better supervised training,
and extend the reconstruction on feature-level to tackle the parameter size
issue and translation issue. The experiments show that the class-encoder helps
to improve the performance on benchmarks of classification and face
recognition. This could also be a promising direction for fast training of face
recognition models.


title:
The Kilodegree Extremely Little Telescope: Searching for Transiting
  Exoplanets in the Northern and Southern Sky

abstract:
  The Kilodegree Extremely Little Telescope (KELT) survey is a ground-based
program designed to search for transiting exoplanets orbiting relatively bright
stars. To achieve this, the KELT Science Team operates two planets facilities -
KELT-North, at Winer Observatory, Arizona, and KELT-South, at the South African
Astronomical Observatory. The telescopes used at these observatories have
particularly wide fields of view, allowing KELT to study a large number of
potential exoplanet host stars. One of the major advantages of targeting bright
stars is that the exoplanet candidates detected can be easily followed up by
small, ground-based observatories distributed around the world. This paper will
provide a brief overview of the KELT-North and the KELT-South surveys, the
follow-up observations preformed by the KELT Follow-up Collaboration, and
exoplanet discoveries confirmed thus far, before concluding with a brief
discussion of the future for the KELT program.


title: Difference-frequency combs in cold atom physics

abstract:
  Optical frequency combs provide the clockwork to relate optical frequencies
to radio frequencies. Hence, combs allow to measure optical frequencies with
respect to a radio frequency where the accuracy is limited only by the
reference signal. In order to provide a stable link between the radio and
optical frequencies, the two parameters of the frequency comb must be fixed:
the carrier envelope offset frequency $f_{\rm ceo}$ and the pulse
repetition-rate $f_{\rm rep}$. We have developed the first optical frequency
comb based on difference frequency generation (DFG) that eliminates $f_{\rm
ceo}$ by design - specifically tailored for applications in cold atom physics.
An $f_{\rm ceo}$-free spectrum at 1550 nm is generated from a super continuum
spanning more than an optical octave. Established amplification and frequency
conversion techniques based on reliable telecom fiber technology allow
generation of multiple wavelength outputs. In this paper we discuss the
frequency comb design, characterization, and optical frequency measurement of
Sr Rydberg states. The DFG technique allows for a compact and robust, passively
$f_{\rm ceo}$ stable frequency comb significantly improving reliability in
practical applications.


title:
Speech Enhancement In Multiple-Noise Conditions using Deep Neural
  Networks

abstract:
  In this paper we consider the problem of speech enhancement in real-world
like conditions where multiple noises can simultaneously corrupt speech. Most
of the current literature on speech enhancement focus primarily on presence of
single noise in corrupted speech which is far from real-world environments.
Specifically, we deal with improving speech quality in office environment where
multiple stationary as well as non-stationary noises can be simultaneously
present in speech. We propose several strategies based on Deep Neural Networks
(DNN) for speech enhancement in these scenarios. We also investigate a DNN
training strategy based on psychoacoustic models from speech coding for
enhancement of noisy speech


title: The fourth order nonlinear Schrodinger limit for quantum Zakharov system

abstract:
  This paper is concerned with the quantum Zakharov system. We prove that when
the ionic speed of sound goes to infinity, the solution to the fourth order
Schrodinger part of the quantum Zakharov system converges to the solution to
quantum modified nonlinear Schrodinger eqaution.


title: Dense output for strong stability preserving Runge-Kutta methods

abstract:
  We investigate dense output formulae (also known as continuous extensions)
for strong stability preserving (SSP) Runge-Kutta methods. We require that the
dense output formula also possess the SSP property, ideally under the same
step-size restriction as the method itself. A general recipe for first-order
SSP dense output formulae for SSP methods is given, and second-order dense
output formulae for several optimal SSP methods are developed. It is shown that
SSP dense output formulae of order 3 and higher do not exist, and that in any
method possessing a second-order SSP dense output, the coefficient matrix A has
a zero row.