title: Contact-aware simulations of particulate Stokesian suspensions

abstract:
  We present an efficient, accurate, and robust method for simulation of dense
suspensions of deformable and rigid particles immersed in Stokesian fluid in
two dimensions. We use a well-established boundary integral formulation for the
problem as the foundation of our approach. This type of formulations, with a
high-order spatial discretization and an implicit and adaptive time
discretization, have been shown to be able to handle complex interactions
between particles with high accuracy. Yet, for dense suspensions, very small
time-steps or expensive implicit solves as well as a large number of
discretization points are required to avoid non-physical contact and
intersections between particles, leading to infinite forces and numerical
instability.
  Our method maintains the accuracy of previous methods at a significantly
lower cost for dense suspensions. The key idea is to ensure interference-free
configuration by introducing explicit contact constraints into the system.
While such constraints are unnecessary in the formulation, in the discrete form
of the problem, they make it possible to eliminate catastrophic loss of
accuracy by preventing contact explicitly.
  Introducing contact constraints results in a significant increase in stable
time-step size for explicit time-stepping, and a reduction in the number of
points adequate for stability.


title: Error mitigation for short-depth quantum circuits

abstract:
  Two schemes are presented that mitigate the effect of errors and decoherence
in short depth quantum circuits. The size of the circuits for which these
techniques can be applied is limited by the rate at which the errors in the
computation are introduced. Near-term applications of early quantum devices,
such as quantum simulations, rely on accurate estimates of expectation values
to become relevant. Decoherence and gate errors lead to wrong estimates of the
expectation values of observables used to evaluate the noisy circuit. The two
schemes we discuss are deliberately simple and don't require additional qubit
resources, so to be as practically relevant in current experiments as possible.
The first method, extrapolation to the zero noise limit, subsequently cancels
powers of the noise perturbations by an application of Richardson's deferred
approach to the limit. The second method cancels errors by resampling
randomized circuits according to a quasi-probability distribution.


title:
Quantifying brain microstructure with diffusion MRI: Theory and
  parameter estimation

abstract:
  We review, systematize and discuss models of diffusion in neuronal tissue, by
putting them into an overarching physical context of coarse-graining over an
increasing diffusion length scale. From this perspective, we view research on
quantifying brain microstructure as occurring along the three major avenues.
The first avenue focusses on the transient, or time-dependent, effects in
diffusion. These effects signify the gradual coarse-graining of tissue
structure, which occurs qualitatively differently in different brain tissue
compartments. We show that studying the transient effects has the potential to
quantify the relevant length scales for neuronal tissue, such as the packing
correlation length for neuronal fibers, the degree of neuronal beading, and
compartment sizes. The second avenue corresponds to the long-time limit, when
the observed signal can be approximated as a sum of multiple non-exchanging
anisotropic Gaussian components. Here the challenge lies in parameter
estimation and in resolving its hidden degeneracies. The third avenue employs
multiple diffusion encoding techniques, able to access information not
contained in the conventional diffusion propagator. We conclude with our
outlook on the future directions which can open exciting possibilities for
designing quantitative markers of tissue physiology and pathology, based on
methods of studying mesoscopic transport in disordered systems.


title: Genus Two Virasoro Correlation Functions for Vertex Operator Algebras

abstract:
  We consider all genus two correlation functions for the Virasoro vacuum
descendants of a vertex operator algebra. These are described in terms of
explicit generating functions that can be combinatorially expressed in terms of
a sequence of globally defined differential operators on which the genus two
Siegel modular group $Sp(4,\mathbb{Z})$ has a natural action.


title:
Isospin-0 $\pi\pi$ s-wave scattering length from twisted mass lattice
  QCD

abstract:
  We present results for the isospin-0 $\pi\pi$ s-wave scattering length
calculated with Osterwalder-Seiler valence quarks on Wilson twisted mass gauge
configurations. We use three $N_f = 2$ ensembles with unitary (valence) pion
mass at its physical value (250$\sim$MeV), at 240$\sim$MeV (320$\sim$MeV) and
at 330$\sim$MeV (400$\sim$MeV), respectively. By using the stochastic Laplacian
Heaviside quark smearing method, all quark propagation diagrams contributing to
the isospin-0 $\pi\pi$ correlation function are computed with sufficient
precision. The chiral extrapolation is performed to obtain the scattering
length at the physical pion mass. Our result $M_\pi a^\mathrm{I=0}_0 =
0.198(9)(6)$ agrees reasonably well with various experimental measurements and
theoretical predictions. Since we only use one lattice spacing, certain
systematics uncertainties, especially those arising from unitary breaking, are
not controlled in our result.


title:
Consistency in the face of change: an adaptive approach to physical
  layer cooperation

abstract:
  Most existing works on physical-layer (PHY) cooperation (beyond routing)
focus on how to best use a given, static relay network--while wireless networks
are anything but static. In this paper, we pose a different set of questions:
given that we have multiple devices within range, which relay(s) do we use for
PHY cooperation, to maintain a consistent target performance? How can we
efficiently adapt, as network conditions change? And how important is it, in
terms of performance, to adapt? Although adapting to the best path when routing
is a well understood problem, how to do so over PHY cooperation networks is an
open question. Our contributions are: (1) We demonstrate via theoretical
evaluation, a diminishing returns trend as the number of deployed relays
increases. (2) Using a simple algorithm based on network metrics, we
efficiently select the sub-network to use at any given time to maintain a
target reliability. (3) When streaming video from Netflix, we experimentally
show (using measurements from a WARP radio testbed employing DIQIF relaying)
that our adaptive PHY cooperation scheme provides a throughput gain of 2x over
nonadaptive PHY schemes, and a gain of 6x over genie-aided IP-level adaptive
routing.


title: 2HDM Charged Higgs Boson Searches at the LHC: Status and Prospects

abstract:
  We review status and prospects of searches for the charged Higgs boson of
2-Higgs Doublet Models of all Yukawa types at the Large Hadron Collider


title: Alfv\'en Waves in the Structured Solar Corona

abstract:
  A simple model of a periodic ensemble of closely packed flux tubes sitting
atop a vertically stratified layer reveals that an incident fast wave from
below preferentially converts almost immediately to Alfv\'en waves in the flux
tubes, with kink waves restricted to at most a very few Fourier modes. This
suggests that observations of coronal kink modes in such structured systems may
greatly underestimate the net wave energy flux being transported into and
through the corona, much of which may reside in harder-to-observe Alfv\'en
waves. The processes of mode conversion/resonant absorption and Alfv\'en phase
mixing are implicated. It is suggested that the Sun's internal p-mode field --
the 5-minute oscillations -- may contribute substantially to the process by
supplying incident fast waves in the chromosphere that scatter and mode-convert
in the tube ensemble.


title: Collaborative Visual Area Coverage using Unmanned Aerial Vehicles

abstract:
  This article addresses the visual area coverage problem using a team of
Unmanned Aerial Vehicles (UAVs). The UAVs are assumed to be equipped with a
downward facing camera covering all points of interest within a circle on the
ground. The diameter of this circular conic-section increases as the UAV flies
at a larger height, yet the quality of the observed area is inverse
proportional to the UAV's height. The objective is to provide a distributed
control algorithm that maximizes a combined coverage-quality criterion by
adjusting the UAV's altitude. Simulation studies are offered to highlight the
effectiveness of the suggested scheme.


title:
A signed version of Putnam's homology theory: Lefschetz and zeta
  functions

abstract:
  A signed version of Putnam homology for Smale spaces is introduced. Its
definition, basic properties and associated Lefschetz theorem are outlined. In
particular, zeta functions associated to an Axiom A diffeomorphism are
compared.


title: Collaborative Visual Area Coverage

abstract:
  This article examines the problem of visual area coverage by a network of
Mobile Aerial Agents (MAAs). Each MAA is assumed to be equipped with a
downwards facing camera with a conical field of view which covers all points
within a circle on the ground. The diameter of that circle is proportional to
the altitude of the MAA, whereas the quality of the covered area decreases with
the altitude. A distributed control law that maximizes a joint coverage-quality
criterion by adjusting the MAAs' spatial coordinates is developed. The
effectiveness of the proposed control scheme is evaluated through simulation
studies.


title:
Magnetically-Induced Optical Transparency on a Forbidden Transition in
  Strontium for Cavity-Enhanced Spectroscopy

abstract:
  In this work we realize a narrow spectroscopic feature using a technique that
we refer to as magnetically-induced optical transparency. A cold ensemble of
$^{88}$Sr atoms interacts with a single mode of a high-finesse optical cavity
via the 7.5kHz linewidth, spin forbidden $^1$S$_0$ to $^3$P$_1$ transition. By
applying a magnetic field that shifts two excited state Zeeman levels, we open
a transmission window through the cavity where the collective vacuum Rabi
splitting due to a single level would create destructive interference for probe
transmission. The spectroscopic feature approaches the atomic transition
linewidth, which is much narrower than the cavity linewidth, and is highly
immune to the reference cavity length fluctuations that limit current
state-of-the-art laser frequency stability.


title: Godel Universe from String Theory

abstract:
  G\"odel universe is a direct product of a line and a three-dimensional
spacetime we call G$_\alpha$. In this paper, we show that the G\"odel metrics
can arise as exact solutions in Einstein-Maxwell-Axion, Einstein-Proca-Axion,
or Freedman-Schwarz gauged supergravity theories. The last allows us to embed
G\"odel universe in string theory. The ten-dimensional spacetime is a direct
product of a line and the nine-dimensional one of an $S^3\times S^3$ bundle
over G$_\alpha$, and it can be interpreted as some decoupling limit of the
rotating D1/D5/D5 intersection. For some appropriate parameter choice, the
nine-dimensional metric becomes an AdS$_3\times S^3$ bundle over squashed
3-sphere. We also study the properties of the G\"odel black holes that are
constructed from the double Wick rotations of the G\"odel metrics.


title:
Electrohydrodynamics of viscous drops in strong electric fields:
  Numerical simulations

abstract:
  Weakly conducting dielectric liquid drops suspended in another dielectric
liquid and subject to an applied uniform electric field exhibit a wide range of
dynamical behaviors contingent on field strength and material properties. These
phenomena are best described by the Melcher-Taylor leaky dielectric model,
which hypothesizes charge accumulation on the drop-fluid interface and
prescribes a balance between charge relaxation, the jump in Ohmic currents from
the bulk and charge convection by the interfacial fluid flow. Most previous
numerical simulations based on this model have either neglected interfacial
charge convection or restricted themselves to axisymmetric drops. In this work,
we develop a three-dimensional boundary element method for the complete leaky
dielectric model to systematically study the deformation and dynamics of liquid
drops in electric fields. The inclusion of charge convection in our simulations
permits us to investigate drops in the Quincke regime, in which experiments
have demonstrated a symmetry-breaking bifurcation leading to steady
electrorotation. Our simulation results show excellent agreement with existing
experimental data and small-deformation theories.


title:
Reggeized model for $\gamma p \to \rho^- \Delta^{++}(1232)$
  photoproduction

abstract:
  A model for the reaction $\gamma p\to\rho^-\Delta^{++}$ is presented with the
$t$-channel $\pi+\rho$ exchanges reggeized to describe the reaction up to high
energies. Gauge invariance of $\rho$ exchange is discussed in connection with
the convergence of the reaction cross section at high energy. The roles of
electromagnetic (EM) multipole moments of $\Delta^{++}$ baryon and of $\rho^-$
meson are analyzed in total and differential cross sections and spin density
matrix elements. Photon polarization asymmetry $\Sigma$ is predicted for a
measurement of electromagnetic moments of $\rho^-$ and of $\Delta^{++}$.


title:
The Anglo-Australian Planet Search XXV: A Candidate Massive Saturn
  Analog Orbiting HD 30177

abstract:
  We report the discovery of a second long-period giant planet orbiting HD
30177, a star previously known to host a massive Jupiter analog (HD 30177b:
a=3.8$\pm$0.1 au, m sin $i=9.7\pm$0.5 Mjup). HD 30177c can be regarded as a
massive Saturn analog in this system, with a=9.9$\pm$1.0 au and m sin
$i=7.6\pm$3.1 Mjup. The formal best fit solution slightly favours a closer-in
planet at $a\sim$7 au, but detailed n-body dynamical simulations show that
configuration to be unstable. A shallow local minimum of longer-period,
lower-eccentricity solutions was found to be dynamically stable, and hence we
adopt the longer period in this work. The proposed $\sim$32 year orbit remains
incomplete; further monitoring of this and other stars is necessary to reveal
the population of distant gas giant planets with orbital separations $a\sim$10
au, analogous to that of Saturn.


title: Wedge-local observables in the deformed sine-Gordon model

abstract:
  In the bootstrap approach to integrable quantum field theories in the
(1+1)-dimensional Minkowski space, one conjectures the two-particle S-matrix
and tries to study local observables. The massless sine-Gordon model is
conjectured to be equivalent to the Thirring model, and its breather-breather
S-matrix components (where the first breather corresponds to the scalar field
of the sine-Gordon model) are closed under fusion. Yet, the residues of the
poles in this breather-breather S-matrix have wrong signs and cannot be
considered as a separate model. We find CDD factors which adjust the signs, so
that the breather-breather S-matrix alone satisfies reasonable assumptions.
Then we propose candidates for observables in wedge-shaped regions and prove
their commutativity in the weak sense.


title:
A Mathematical Analysis of Dressed Photon in Ground State of Generalized
  Quantum Rabi Model Using Pair Theory

abstract:
  We consider the generalized quantum Rabi model with the so-called
$A^{2}$-term in the light of the Hepp-Lieb-Preparata quantum phase transition.
We investigate the dressed photon in its ground state when the atom-light
coupling strength is in the deep-strong coupling regime. We show how the
dressed photon appears in the ground state. We dedicate this paper to Pavel
Exner and Herbert Spohn on the occasion of their 70th birthdays, and Klaus Hepp
on the occasion of his 80th birthday.


title: CP(N) sigma model on a finite interval revisited

abstract:
  In this short note we will revisit the large $N$ solution of $\mathbb{C}P^N$
sigma model on a finite interval of length $L$. We will find a family of
boundary conditions for which the large $N$ saddle point can be found
analytically. For a certain choice of the boundary conditions the theory has
only one phase for all values of $L$. Also, we will provide an example when
there are two phases: for large $L$ there is a standard phase with an unbroken
$U(1)$ gauge symmetry and for small $L$ there is Higgs phase with a broken
gauge symmetry.


title:
Stimulated X-ray Raman scattering in Free Electron Lasers with
  incoherent spectrum

abstract:
  The single-pulse spectrum of self-amplified spontaneous emission (SASE) free
electron lasers (FELs) is characterized by random fluctuations in frequency.
The typical spectrum bandwidth for a hard x-ray FEL is in the range of 10-20 eV
and is comparable with the distance between energy levels of valence electrons
in atoms an molecules. We calculate the rate of transitions in a quantum
three-level system with the energy difference of several eV caused by such
radiation and show that for x-ray intensities in the range of $10^{20}$
W/cm$^2$ the probability of the transition over the duration of the x-ray pulse
is large. We argue that this effect can be used to modify the spectrum of a
SASE FEL potentially making it more narrow.


title:
Multi-instrument observations of a failed flare eruption associated with
  MHD waves in a loop bundle

abstract:
  We present observations of a B7.9-class flare that occurred on the 24th
January, 2015, using the Atmopsheric Imaging Assembly (AIA) of the Solar
Dynamics Observatory (SDO), the EUV Imaging Spectrometer (EIS) and the X-Ray
Telescope of Hinode. The flare triggers the eruption of a dense cool plasma
blob as seen in AIA 171\AA,\, which is unable to completely break out and
remains confined within a local bundle of active region loops. During this
process, transverse oscillations of the threads are observed. The cool plasma
is then observed to descend back to the chromosphere along each loop strand. At
the same time, a larger diffuse co-spatial loop observed in the hot wavebands
of SDO/AIA and Hinode/XRT is formed, exhibiting periodic intensity variations
along its length. The formation and evolution of magnetohydrodynamic (MHD)
waves depend upon the values of the local plasma parameters (e.g. density,
temperature and magnetic field), which can hence be inferred by coronal
seismology. In this study we aim to assess how the observed MHD modes are
affected by the variation of density and temperature. We combined analysis of
EUV/X-ray imaging and spectroscopy using SDO/AIA, Hinode/EIS and XRT. We show
that the evolution of the detected waves is determined by the temporal
variations of the local plasma parameters, caused by the flare heating and the
consequent cooling. We apply coronal seismology to both waves obtaining
estimations of the background plasma parameters.


title: Strongly self-absorbing C*-dynamical systems, III

abstract:
  In this paper, we accomplish two objectives. Firstly, we extend and improve
some results in the theory of (semi-)strongly self-absorbing C*-dynamical
systems, which was introduced and studied in previous work. In particular, this
concerns the theory when restricted to the case where all the semi-strongly
self-absorbing actions are assumed to be unitarily regular, which is a mild
technical condition. The central result in the first part is a strengthened
version of the equivariant McDuff-type theorem, where equivariant tensorial
absorption can be achieved with respect to so-called very strong cocycle
conjugacy.
  Secondly, we establish completely new results within the theory. This mainly
concerns how equivariantly $\cal Z$-stable absorption can be reduced to
equivariantly UHF-stable absorption with respect to a given semi-strongly
self-absorbing action. Combining these abstract results with known uniqueness
theorems due to Matui and Izumi-Matui, we obtain the following main result. If
$G$ is a torsion-free abelian group and $\cal D$ is one of the known strongly
self-absorbing C*-algebras, then strongly outer $G$-actions on $\cal D$ are
unique up to (very strong) cocycle conjugacy. This is new even for
$\mathbb{Z}^3$-actions on the Jiang-Su algebra.


title:
Slowly varying, macroscale models emerge from microscale dynamics over
  multiscale domains

abstract:
  Many physical systems are well described on domains which are relatively
large in some directions but relatively thin in other directions. In this
scenario we typically expect the system to have emergent structures that vary
slowly over the large dimensions. For practical mathematical modelling of such
systems we require efficient and accurate methodologies for reducing the
dimension of the original system and extracting the emergent dynamics. Common
mathematical approximations for determining the emergent dynamics often rely on
self-consistency arguments or limits as the aspect ratio of the 'large' and
'thin' dimensions becomes unphysically infinite. Here we build on a new
approach, previously establish for systems which are large in only one
dimension, which analyses the dynamics at each cross-section of the domain with
a rigorous multivariate Taylor series. Then centre manifold theory supports the
local modelling of the system's emergent dynamics with coupling to neighbouring
cross-sections treated as a non-autonomous forcing. The union over all
cross-sections then provides powerful support for the existence and emergence
of a centre manifold model global in the large finite domain. Quantitative
error estimates are determined from the interactions between the cross-section
coupling and both fast and slow dynamics. Two examples provide practical
details of our methodology. The approach developed here may be used to quantify
the accuracy of known approximations, to extend such approximations to mixed
order modelling, and to open previously intractable modelling issues to new
tools and insights.


title:
Compactness, existence and multiplicity for the singular mean field
  problem with sign-changing potentials

abstract:
  In this paper we consider a mean field problem on a compact surface with
conical singularities. This problem appears in the Gaussian curvature
prescription problem in Geometry, and also in the Electroweak Theory and in the
abelian Chern-Simons-Higgs model in Physics. In this paper we focus on the case
of sign-changing potentials, and we give results on compactness, existence and
multiplicity of solutions.


title:
Neutrino and CP-even Higgs boson masses in a nonuniversal
  $\mathrm{U}(1)'$ extension

abstract:
  We propose a new anomaly-free and family nonuniversal $\mathrm{U}(1)'$
extension of the standard model with the addition of two scalar singlets and a
new scalar doublet. The quark sector is extended by adding three exotic quark
singlets, while the lepton sector includes two exotic charged lepton singlets,
three right-handed neutrinos and three sterile Majorana leptons to obtain the
fermionic mass spectrum of the standard model. The lepton sector also
reproduces the elements of the PMNS matrix and the squared-mass differences
data from neutrino oscillation experiments. Also, analytical relations of the
PMNS matrix are derived via the inverse see-saw mechanism, and numerical
predictions of the parameters in both normal and inverse order scheme for the
mass of the phenomenological neutrinos are obtained. We employed a simple
seesaw-like method to obtain analytical mass eigenstates of the CP-even
$3\times 3$ mass matrix of the scalar sector.


title:
A Galerkin finite element method for time-fractional stochastic heat
  equation

abstract:
  In this study, a Galerkin finite element method is presented for
time-fractional stochastic heat equation driven by multiplicative noise, which
arises from the consideration of heat transport in porous media with thermal
memory with random effects. The spatial and temporal regularity properties of
mild solution to the given problem under certain sufficient conditions are
obtained. Numerical techniques are developed by the standard Galerkin finite
element method in spatial direction, and Gorenflo-Mainardi-Moretti-Paradisi
scheme is applied in temporal direction. The convergence error estimates for
both semi-discrete and fully discrete schemes are established. Finally,
numerical example is provided to verify the theoretical results.


title:
External luminescence and photon recycling in near-field
  thermophotovoltaics

abstract:
  The importance of considering near-field effects on photon recycling and
spontaneous emission in a thermophotovoltaic device is investigated.
Fluctuational electrodynamics is used to calculate external luminescence from a
photovoltaic cell as a function of emitter type, vacuum gap thickness between
emitter and cell, and cell thickness. The observed changes in external
luminescence suggest strong modifications of photon recycling caused by the
presence of the emitter. Photon recycling for propagating modes is affected by
reflection at the vacuum-emitter interface and is substantially decreased by
the leakage towards the emitter through tunneling of frustrated modes. In
addition, spontaneous emission by the cell can be strongly enhanced by the
presence of an emitter supporting surface polariton modes. It follows that
using a radiative recombination model with a spatially uniform radiative
lifetime, even corrected by a photon recycling factor, is inappropriate.
Applying the principles of detailed balance, and accounting for non-radiative
recombination mechanisms, the impact of external luminescence enhancement in
the near field on thermophotovoltaic performance is investigated. It is shown
that unlike isolated cells, the external luminescence efficiency is not solely
dependent on cell quality, but significantly increases as the vacuum gap
thickness decreases below 400 nm for the case of an intrinsic silicon emitter.
In turn, the open-circuit voltage and power density benefit from this enhanced
external luminescence toward the emitter. This benefit is larger as cell
quality, characterized by the contribution of non-radiative recombination,
decreases.


title: Minors of a random binary matroid

abstract:
  Let ${\bf A}={\bf A}_{n,m,k}$ be a random $n\times m$ matrix over
$\mathbf{GF}_2$ wher each column consists of $k$ randomly chosen ones. Let $M$
be an arbirary fixed binary matroid. We show that if $m/n$ and $k$ are
sufficiently large then as $n\to\infty$ the binary matroid induced by {\bf A}
contains $M$ as a minor.


title:
Information Content Analysis for Selection of Optimal JWST Observing
  Modes for Transiting Exoplanet Atmospheres

abstract:
  The James Webb Space Telescope (JWST) is nearing its launch date of 2018, and
will undoubtedly revolutionize our knowledge of exoplanet atmospheres. While
several studies have explored what the limits of the telescope will be in terms
of exoplanet characterization, less has been done to specifically identify
which observing modes will be most useful for characterizing a diverse range of
exoplanetary atmospheres. We use an information content based approach commonly
used in the studies of Solar System atmospheres. We develop a system based upon
these information content methods to trace the instrumental and atmospheric
model phase space in order to identify which observing modes are best suited
for particular classes of planets, focusing on transmission spectra.
Specifically, the atmospheric parameter space we cover is T=600-1800 K,
C/O=0.55-1, [M/H]=1-100$\times$Solar for a R=1.39 R$_J$, M=0.59 M$_J$ planet
orbiting WASP-62-like star. We find that obtaining broader wavelength coverage
over multiple modes is preferred over higher precision in a single mode given
the same amount of observing time. Regardless of the planet temperature and
composition, the best modes for constraining terminator temperatures, C/O
ratios, and metalicity are NIRISS SOSS+NIRSpec G395. If the target's host star
is dim enough such that the NIRSpec prism can be used, then it cam be used
instead of NIRISS SOSS+NIRSpec G395. Lastly, observations that use more than
two modes, should be carefully analyzed because sometimes the addition of a
third mode results in no gain of information. In these cases, higher precision
in the original two modes is favorable.


title: Cluster states in stable and unstable nuclei

abstract:
  In this contribution, I will discuss two topics related to the clustering of
atomic nuclei. The first is dual character of the ground state. Recently, it
was pointed out that the ground states of atomic nuclei have dual character of
shell and cluster implying that both of the single-particle excitation and
cluster excitation occur as the fundamental excitation modes. The isoscalar
monopole and dipole transitions are regarded as the triggers to induce the
cluster excitation. By referring the Hartree-Fock and antisymmetrized molecular
dynamics calculations, the dual character and those transitions are explained.
The second is the linear-chain state of $^{16}{\rm C}$ in which the linearly
aligned 3$\alpha$ particles are sustained by the valence neutrons. The rather
convincing evidences for this exotic state are very recently reported by
several experiments. Here, I introduce a couple of theoretical analysis and
predictions.


title:
Finite-Difference Time-Domain (FDTD) Modelling of Space-Time Modulated
  Metasurfaces

abstract:
  A finite-difference time-domain (FDTD) modelling of finite-size zero
thickness space-time modulated Huygens' metasurfaces based on Generalized Sheet
Transition Conditions (GSTCs), is proposed and numerically demonstrated. A
typical all-dielectric Huygens' unit cell is taken as an example and its
material permittivity is modulated in both space and time, to emulate a
travelling-type spatio-temporal perturbation on the metasurface. By mapping the
permittivity variation onto the parameters of the equivalent Lorentzian
electric and magnetic susceptibility densities, $\tilde{\chi}_\text{ee}$ and
$\tilde{\chi}_\text{mm}$, the problem is formulated into a set of second-order
differential equations in time with non-constant coefficients. The resulting
field solutions are then conveniently solved using an explicit
finite-difference technique and integrated with a Yee-cell based propagation
region to visualize the scattered fields taking into account the various
diffractive effects from the metasurface of finite size. Several examples are
shown for both linear and space-time varying metasurfaces which are excited
with normally incident plane and Gaussian beams, showing detailed scattering
field solutions. While the time-modulated metasurface leads to the generation
of new collinearly propagating temporal harmonics, these harmonics are
angularly separated in space, when an additional space modulation is introduced
in the metasurface.


title:
Transition-based versus State-based Reward Functions for MDPs with
  Value-at-Risk

abstract:
  In reinforcement learning, the reward function on current state and action is
widely used. When the objective is about the expectation of the (discounted)
total reward only, it works perfectly. However, if the objective involves the
total reward distribution, the result will be wrong. This paper studies
Value-at-Risk (VaR) problems in short- and long-horizon Markov decision
processes (MDPs) with two reward functions, which share the same expectations.
Firstly we show that with VaR objective, when the real reward function is
transition-based (with respect to action and both current and next states), the
simplified (state-based, with respect to action and current state only) reward
function will change the VaR. Secondly, for long-horizon MDPs, we estimate the
VaR function with the aid of spectral theory and the central limit theorem.
Thirdly, since the estimation method is for a Markov reward process with the
reward function on current state only, we present a transformation algorithm
for the Markov reward process with the reward function on current and next
states, in order to estimate the VaR function with an intact total reward
distribution.


title: Internal Charmonium Evolution in the Quark-Gluon Plasma

abstract:
  We employ a time-dependent Schr\"odinger equation to study the evolution of a
$c\bar c$ dipole in a quark-gluon plasma (QGP). Medium effects on the
heavy-quark potential in the QGP are found to significantly affect the
timescales of the internal evolution of the dipole. Color-screening can enhance
the overlap of the expanding wavepackage with excited states at high
temperature, while it is reduced at lower temperatures where the dipole favors
the formation of the charmonium ground state. We investigate the consequences
of this mechanism on the double ratio of charmonium nuclear modification
factors, $R_{AA}^{\psi(2S)}/R_{AA}^{J/\psi}$, in heavy-ion collisions. The
impact of the transition mechanisms on this ratio turns out to be rather
sensitive to the attractive strength of the potential, and to its temperature
dependence.


title:
Nonparametric Tests for Treatment Effect Heterogeneity with Duration
  Outcomes

abstract:
  This article proposes different tests for treatment effect heterogeneity when
the outcome of interest, typically a duration variable, may be right-censored.
The proposed tests study whether a policy 1) has zero distributional (average)
effect for all subpopulations defined by covariate values, and 2) has
homogeneous average effect across different subpopulations. The proposed tests
are based on two-step Kaplan-Meier integrals and do not rely on parametric
distributional assumptions, shape restrictions, or on restricting the potential
treatment effect heterogeneity across different subpopulations. Our framework
is suitable not only to exogenous treatment allocation but can also account for
treatment noncompliance - an important feature in many applications. The
proposed tests are consistent against fixed alternatives, and can detect
nonparametric alternatives converging to the null at the parametric
$n^{-1/2}$-rate, $n$ being the sample size. Critical values are computed with
the assistance of a multiplier bootstrap. The finite sample properties of the
proposed tests are examined by means of a Monte Carlo study and an application
about the effect of labor market programs on unemployment duration. Open-source
software is available for implementing all proposed tests.


title: Coherent back and forward scattering peaks in the quantum kicked rotor

abstract:
  We propose and analyze an experimental scheme using the quantum kicked rotor
to observe the newly-predicted coherent forward scattering peak together with
its long-known twin brother, the coherent backscattering peak. Contrary to
coherent backscattering, which arises already under weak-localization
conditions, coherent forward scattering is only triggered by Anderson or strong
localization. So far, coherent forward scattering has not been observed in
conservative systems with elastic scattering by spatial disorder. We propose to
turn to the quantum kicked rotor, which has a long and succesful history as an
accurate experimental platform to observe dynamical localization, i.e.,
Anderson localization in momentum space. We analyze the coherent forward
scattering effect for the quantum kicked rotor by extensive numerical
simulations, both in the orthogonal and unitary class of disordered quantum
systems, and show that an experimental realization involving phase-space
rotation techniques is within reach of state-of-the-art cold-atom experiments.


title:
On finite size effects, ensemble choice and force influence in
  dissipative particle dynamics simulations

abstract:
  The influence of finite size effects, choice of statistical ensemble and
contribution of the forces in numerical simulations using the dissipative
particle dynamics (DPD) model are revisited here. Finite size effects in stress
anisotropy, interfacial tension and dynamic viscosity are computed and found to
be minimal with respect to other models. Additionally, the choice of ensemble
is found to be of fundamental importance for the accurate calculation of
properties such as the solvation pressure, especially for relatively small
systems. Lastly, the contribution of the random, dissipative and conservative
forces that make up the DPD model in the prediction of properties of simple
liquids such as the pressure is studied as well. Some tricks of the trade are
provided, which may be useful for those carrying out high-performance numerical
simulations using the DPD model.


title:
High order ADER schemes for a unified first order hyperbolic formulation
  of Newtonian continuum mechanics coupled with electro-dynamics

abstract:
  In this paper, we propose a new unified first order hyperbolic model of
Newtonian continuum mechanics coupled with electro-dynamics. The model is able
to describe the behavior of moving elasto-plastic dielectric solids as well as
viscous and inviscid fluids in the presence of electro-magnetic fields. It is
actually a very peculiar feature of the proposed PDE system that viscous fluids
are treated just as a special case of elasto-plastic solids. This is achieved
by introducing a strain relaxation mechanism in the evolution equations of the
distortion matrix. The model also contains a hyperbolic formulation of heat
conduction as well as a dissipative source term in the evolution equations for
the electric field given by Ohm's law. Via formal asymptotic analysis we show
that in the stiff limit, the governing first order hyperbolic PDE system with
relaxation source terms tends asymptotically to the well-known viscous and
resistive magnetohydrodynamics (MHD) equations. The governing PDE system is
symmetric hyperbolic and satisfies the first and second principle of
thermodynamics, hence it belongs to the so-called class of symmetric hyperbolic
thermodynamically compatible systems (HTC). An important feature of the
proposed model is that the propagation speeds of all physical processes,
including dissipative processes, are finite. The model is discretized using
high order accurate ADER discontinuous Galerkin (DG) finite element schemes
with a posteriori subcell finite volume limiter and using high order ADER-WENO
finite volume schemes. We show numerical test problems that explore a rather
large parameter space of the model ranging from ideal MHD, viscous and
resistive MHD over pure electro-dynamics to moving dielectric elastic solids in
a magnetic field.


title: $B\rightarrow X_{_S}l^+l^-$ in the minimal gauged $(B-L)$ supersymmetry

abstract:
  Applying the effective Hamilton for $b\rightarrow sl^+l^-,\;(l=e,\;\mu)$ in
the framework of minimal supersymmetric extension of the standard model with
local $B-L$ gauge symmetry, we investigate branching ratios and
forward-backward asymmetries of rare decay $B\rightarrow X_{_S}l^+l^-$ in low
and high $q^2$ regions, respectively. In addition we also study the $CP$
asymmetries depending on new $CP$ phases from soft breaking terms in low and
high $q^2$ regions. With some assumptions on parameter space of the model, the
numerical analyses of the supersymmetric contributions to the branching ratios,
forward-backward and $CP$ asymmetries of $B\rightarrow X_{_S}l^+l^-$ are
presented in low and high $q^2$ regions, respectively.


title:
ExtremeWeather: A large-scale climate dataset for semi-supervised
  detection, localization, and understanding of extreme weather events

abstract:
  Then detection and identification of extreme weather events in large-scale
climate simulations is an important problem for risk management, informing
governmental policy decisions and advancing our basic understanding of the
climate system. Recent work has shown that fully supervised convolutional
neural networks (CNNs) can yield acceptable accuracy for classifying well-known
types of extreme weather events when large amounts of labeled data are
available. However, many different types of spatially localized climate
patterns are of interest including hurricanes, extra-tropical cyclones, weather
fronts, and blocking events among others. Existing labeled data for these
patterns can be incomplete in various ways, such as covering only certain years
or geographic areas and having false negatives. This type of climate data
therefore poses a number of interesting machine learning challenges. We present
a multichannel spatiotemporal CNN architecture for semi-supervised bounding box
prediction and exploratory data analysis. We demonstrate that our approach is
able to leverage temporal information and unlabeled data to improve the
localization of extreme weather events. Further, we explore the representations
learned by our model in order to better understand this important data. We
present a dataset, ExtremeWeather, to encourage machine learning research in
this area and to help facilitate further work in understanding and mitigating
the effects of climate change. The dataset is available at
extremeweatherdataset.github.io and the code is available at
https://github.com/eracah/hur-detect.


title: Bacon-Shor code with continuous measurement of non-commuting operators

abstract:
  We analyze the operation of a four-qubit Bacon-Shor code with simultaneous
continuous measurement of non-commuting gauge operators. The error syndrome in
this case is monitored via time-averaged cross-correlators of the output
signals. We find the logical error rate for several models of decoherence, and
also find the termination rate for this quantum error detecting code. The code
operation is comparable to that based on projective measurements when the
collapse timescale due to continuous measurements is an order of magnitude less
than the time period between the projective measurements. An advantage of the
continuous-measurement implementation is the absence of time-dependence in the
code operation, with passive continuous monitoring of the error syndrome.


title:
An Empirical Fitting Method for Type Ia Supernova Light Curves: A Case
  Study of SN 2011fe

abstract:
  We present a new empirical fitting method for the optical light curves of
Type Ia supernovae (SNe~Ia). We find that a variant broken-power-law function
provides a good fit, with the simple assumption that the optical emission is
approximately the blackbody emission of the expanding fireball. This function
is mathematically analytic and is derived directly from the photospheric
velocity evolution. When deriving the function, we assume that both the
blackbody temperature and photospheric velocity are constant, but the final
function is able to accommodate these changes during the fitting procedure.
Applying it to the case study of SN~2011fe gives a surprisingly good fit that
can describe the light curves from the first-light time to a few weeks after
peak brightness, as well as over a large range of fluxes ($\sim 5$\, mag, and
even $\sim 7$\,mag in the $g$ band). Since SNe~Ia share similar light-curve
shapes, this fitting method has the potential to fit most other SNe~Ia and
characterize their properties in large statistical samples such as those
already gathered and in the near future as new facilities become available.


title:
Multiplicity and clustering in Taurus star-forming region. I. Unexpected
  ultra-wide pairs of high-order multiplicity in Taurus

abstract:
  We collected the multiplicity data of stars in Taurus to build an up-to-date
stellar/multiplicity catalog. After a general study of nearest-neighbor
statistics on spatial random distribution, we introduce the one-point
correlation $\Psi$ function to complement the pair correlation function and
define the spatial regimes departing from randomness in Taurus. We then perform
a set of statistical studies to characterize the binary regime that prevails in
Taurus. The $\Psi$ function in Taurus has a scale-free trend with a similar
exponent as the correlation function at small scale. It extends almost 3
decades up to $\sim 60$ kAU showing a potential extended wide binary regime.
This was hidden in the correlation function due to the clustering pattern
blending. Distinguishing two stellar populations, single stars versus multiple
systems (separation $ \leq 1$ kAU), within Class II/III stars observed at high
angular resolution, we highlight a major spatial neighborhood difference
between the two populations using nearest-neighbor statistics. The multiple
systems are three times more likely to have a distant companion within 10 kAU
when compared to single stars. We show that this is due to the presence of most
probable physical ultra-wide pairs. These UWPs are biased towards high
multiplicity and higher-stellar-mass components at shorter separations. The
multiplicity fraction per ultra-wide pair with separation less than 10 kAU may
be as high as 83.5 $\pm$ 19.6\%. We suggest that these young pre-main sequence
UWPs may be pristine imprints of their spatial configuration at birth resulting
from a cascade fragmentation scenario of the natal molecular core. They could
be the older counterparts, at least for those separated by less than 10 kAU, to
the $\le$ 0.5 Myr prestellar cores/Class 0 multiple objects observed at
radio/mm wavelengths.


title:
Statistical and Computational Guarantees of Lloyd's Algorithm and its
  Variants

abstract:
  Clustering is a fundamental problem in statistics and machine learning.
Lloyd's algorithm, proposed in 1957, is still possibly the most widely used
clustering algorithm in practice due to its simplicity and empirical
performance. However, there has been little theoretical investigation on the
statistical and computational guarantees of Lloyd's algorithm. This paper is an
attempt to bridge this gap between practice and theory. We investigate the
performance of Lloyd's algorithm on clustering sub-Gaussian mixtures. Under an
appropriate initialization for labels or centers, we show that Lloyd's
algorithm converges to an exponentially small clustering error after an order
of $\log n$ iterations, where $n$ is the sample size. The error rate is shown
to be minimax optimal. For the two-mixture case, we only require the
initializer to be slightly better than random guess.
  In addition, we extend the Lloyd's algorithm and its analysis to community
detection and crowdsourcing, two problems that have received a lot of attention
recently in statistics and machine learning. Two variants of Lloyd's algorithm
are proposed respectively for community detection and crowdsourcing. On the
theoretical side, we provide statistical and computational guarantees of the
two algorithms, and the results improve upon some previous signal-to-noise
ratio conditions in literature for both problems. Experimental results on
simulated and real data sets demonstrate competitive performance of our
algorithms to the state-of-the-art methods.


title: Auxetic deformations and elliptic curves

abstract:
  The problem of detecting auxetic behavior, originating in materials science
and mathematical crystallography, refers to the property of a flexible periodic
bar-and-joint framework to widen, rather than shrink, when stretched in some
direction. The only known algorithmic solution for detecting infinitesimal
auxeticity is based on the rather heavy machinery of fixed-dimension
semi-definite programming. In this paper we present a new, simpler algorithmic
approach which is applicable to a natural family of 3D periodic bar-and-joint
frameworks with 3 degrees-of-freedom. This class includes most zeolite
structures, which are important for applications in computational materials
science. We show that the existence of auxetic deformations is related to
properties of an associated elliptic curve. A fast algorithm for recognizing
auxetic capabilities is obtained via the classical Aronhold invariants of the
cubic form defining the curve.


title: Bottom-Up Top-Down Cues for Weakly-Supervised Semantic Segmentation

abstract:
  We consider the task of learning a classifier for semantic segmentation using
weak supervision in the form of image labels which specify the object classes
present in the image. Our method uses deep convolutional neural networks (CNNs)
and adopts an Expectation-Maximization (EM) based approach. We focus on the
following three aspects of EM: (i) initialization; (ii) latent posterior
estimation (E-step) and (iii) the parameter update (M-step). We show that
saliency and attention maps, our bottom-up and top-down cues respectively, of
simple images provide very good cues to learn an initialization for the
EM-based algorithm. Intuitively, we show that before trying to learn to segment
complex images, it is much easier and highly effective to first learn to
segment a set of simple images and then move towards the complex ones. Next, in
order to update the parameters, we propose minimizing the combination of the
standard softmax loss and the KL divergence between the true latent posterior
and the likelihood given by the CNN. We argue that this combination is more
robust to wrong predictions made by the expectation step of the EM method. We
support this argument with empirical and visual results. Extensive experiments
and discussions show that: (i) our method is very simple and intuitive; (ii)
requires only image-level labels; and (iii) consistently outperforms other
weakly-supervised state-of-the-art methods with a very high margin on the
PASCAL VOC 2012 dataset.


title: Multiplicity of nodal solutions to the Yamabe problem

abstract:
  Given a compact Riemannian manifold $(M,g)$ without boundary of dimension
$m\geq 3$ and under some symmetry assumptions, we establish existence of one
positive and multiple nodal solutions to the Yamabe-type equation
$$-div_{g}(a\nabla u)+bu=c|u|^{2^{\ast}-2}u\quad on\ M$$ where $a,b,c\in
C^{\infty}(M)$, $a$ and $c$ are positive, $-div_{g}(a\nabla)+b$ is coercive,
and $2^{\ast}=\frac{2m}{m-2}$ is the critical Sobolev exponent. In particular,
if $R_{g}$ denotes the scalar curvature of $(M,g)$, we give conditions which
guarantee that the Yamabe problem $$\Delta_{g}u+\frac{m-2}{4(m-1} R_{g}u=\kappa
u^{2^{\ast}-2}\quad on\ M$$ admits a prescribed number of nodal solutions.


title: Richer Convolutional Features for Edge Detection

abstract:
  In this paper, we propose an accurate edge detector using richer
convolutional features (RCF). Since objects in nature images have various
scales and aspect ratios, the automatically learned rich hierarchical
representations by CNNs are very critical and effective to detect edges and
object boundaries. And the convolutional features gradually become coarser with
receptive fields increasing. Based on these observations, our proposed network
architecture makes full use of multiscale and multi-level information to
perform the image-to-image edge prediction by combining all of the useful
convolutional features into a holistic framework. It is the first attempt to
adopt such rich convolutional features in computer vision tasks. Using VGG16
network, we achieve \sArt results on several available datasets. When
evaluating on the well-known BSDS500 benchmark, we achieve ODS F-measure of
\textbf{.811} while retaining a fast speed (\textbf{8} FPS). Besides, our fast
version of RCF achieves ODS F-measure of \textbf{.806} with \textbf{30} FPS.


title: Axion Dark Matter Induced Cosmic Microwave Background $B$-modes

abstract:
  It was known that isocurvature perturbation of a nearly massless cosmological
axion field can lead to rotation of $E$-mode polarization into $B$-mode
polarization in the cosmic microwave background (CMB) by the presence of a
parity violating coupling of the field to the topological density of
electromagnetism, resulting in a phenomenon known as anisotropic cosmic
birefringence. In this {\em Letter}, we propose a new source of anisotropic
cosmic birefringence induced by dark matter adiabatic density perturbation. If
dark matter is ultralight axions that carry a coupling to photon, its adiabatic
density fluctuations will induce anisotropic cosmic birefringence with a
blue-tilted rotation power spectrum, thus generating CMB $B$-mode polarization
on sub-degree angular scales. Using current POLARBEAR and SPTPol $B$-mode
polarization data, we derive a constraint on the axion-photon coupling strength
($\beta$) and the axion mass ($m$), $\beta^2 (10^{-22}{\rm eV}/m)^2 < 8\times
10^{15}$. It is shown that the birefringence $B$ modes can dominate over CMB
lensing $B$ modes at high $l$, manifesting as an excess power for $l>1500$ in
future CMB lensing $B$-mode searches. In addition, we derive the
lensing-rotation cross correlation that can be a potential test to the present
model.


title: Local and global coincidence homology classes

abstract:
  For two differentiable maps between two manifolds of possibly different
dimensions, the local and global coincidence homology classes are introduced
and studied by Bisi- Bracci-Izawa-Suwa (2016) in the framework of Cech-de Rham
cohomology. We take up the problem from the combinatorial viewpoint and give
some finer results, in particular for the local classes. As to the global
class, we clarify the relation with the cohomology coincidence class as studied
by Biasi-Libardi-Monis (2015). In fact they introduced such a class in the
context of several maps and we also consider this case. In particular we define
the local homology class and give some explicit expressions. These all together
lead to a generalization of the classical Lefschetz coincidence point formula.


title: On Free $\omega$-Continuous and Regular Ordered Algebras

abstract:
  We study varieties of certain ordered $\Sigma$-algebras with restricted
completeness and continuity properties. We give a general characterization of
their free algebras in terms of submonads of the monad of $\Sigma$-coterms.
Varieties of this form are called \emph{quasi-regular}. For example, we show
that if $E$ is a set of inequalities between finite $\Sigma$-terms, and if
$\mathcal{V}_\omega$ and $\mathcal{V}_\mathrm{reg}$ denote the varieties of all
$\omega$-continuous ordered $\Sigma$-algebras and regular ordered
$\Sigma$-algebras satisfying $E$, respectively, then the free
$\mathcal{V}_\mathrm{reg}$-algebra $F_\mathrm{reg}(X)$ on generators $X$ is the
subalgebra of the corresponding free $\mathcal{V}_\omega$-algebra $F_\omega(X)$
determined by those elements of $F_\omega(X)$ denoted by the regular
$\Sigma$-coterms. This is a special case of a more general construction that
applies to any quasi-regular family. Examples include the *-continuous Kleene
algebras, context-free languages, $\omega$-continuous semirings and
$\omega$-continuous idempotent semirings, OI-macro languages, and iteration
theories.


title: Nonnormal Quotients

abstract:
  We present a natural extension of the process of taking a group quotient to
arbitrary subgroups. We first review basic concepts from group theory. This
will allow us to see the relationship between our new, more general quotient
operation and the standard group quotient. In particular, we will find that a
naive attempt to perform the quotient process with a nonnormal subgroup
actually leads to a well-defined operation which can be easily characterized
with existing terminology.


title: Mechanical Properties of Transcription

abstract:
  Recently the physical characterization of a number of biological processes
has proven indispensable for a full understanding of natural phenomena. One
such example is the mechanical properties of transcription, which have been
shown to have significant effects in gene expression. In this letter we
introduce a simple description of the basic physical elements of transcription
where RNA elongation, RNA polymerase rotation and DNA supercoiling are coupled.
The resulting framework describes the relative amount of RNA polymerase
rotation and DNA supercoiling that occurs during RNA elongation. Asymptotic
behavior is derived and can be used to experimentally extract unknown
mechanical parameters of transcription. Incorporation of mechanical limits to
RNA polymerase is accomplished yielding an equation of motion for DNA
supercoiling and RNA elongation with transcriptional stalling. Important
implications for gene expression, chromatin structure and genome organization
are discussed.


title:
A Generalized Mixed-Integer Convex Program for Multilegged Footstep
  Planning on Uneven Terrain

abstract:
  Robot footstep planning strategies can be divided in two main approaches:
discrete searches and continuous optimizations. While discrete searches have
been broadly applied, continuous optimizations approaches have been restricted
for humanoid platforms. This article introduces a generalized
continuous-optimization approach for multilegged footstep planning which can be
adapted to different platforms, regardless the number and geometry of legs.
This approach leverages Mixed-Integer Convex Programming to account for the
non-convex constraints that represent footstep rotation and obstacle avoidance.
The planning problem is formulated as an optimization problem which considers
robot geometry and reachability with linear constraints, and can be efficiently
solved using optimization software. To demonstrate the functionality and
adaptability of the planner, a set of tests are performed on a BH3R hexapod and
a LittleDog quadruped on scenarios which can't be easily handled with discrete
searches, such tests are solved efficiently in fractions of a second. This work
represents, to the knowledge of the authors, the first successful
implementation of a continuous optimization-based multilegged footstep planner.


title:
Beyond the Kinetic Chain Process in a Stroke using a Triple Pendulum
  Model

abstract:
  The efficient way to transfer input potential energy to the kinetic energy of
a racket or bat was analyzed by two coupled harmonic triple pendulums. We find
the most efficient way to transfer energy based on the kinetic chain process.
Using control parameters, such as the release times, lengths and masses of the
triple pendulum, we optimize the kinetic chain process. We also introduce a new
method to get an efficient way to transfer initial energy to the kinetic energy
of the third rod in the triple pendulum without time delay, which is considered
an essential part of a kinetic chain process.


title:
Knowledge Space Framework: An API for representation, persistence and
  visualization of knowledge spaces

abstract:
  This paper will discuss the challenges in tooling around the management and
utilization of knowledge space structures, via standardized APIs for external
Adaptive Learning Systems (ALS) to consume. It then describes how these
challenges are addressed in a graph based knowledge management framework
application designed for external ALSs.


title: Financial market with no riskless (safe) asset

abstract:
  We study markets with no riskless (safe) asset. We derive the corresponding
Black-Scholes-Merton option pricing equations for markets where there are only
risky assets which have the following price dynamics: (i) continuous
diffusions; (ii) jump-diffusions; (iii) diffusions with stochastic
volatilities, and; (iv) geometric fractional Brownian and Rosenblatt motions.
No arbitrage and market completeness conditions are derived in all four cases.


title:
Fountain Code-Inspired Channel Estimation for Multi-user Millimeter Wave
  MIMO Systems

abstract:
  This paper develops a novel channel estimation approach for multi-user
millimeter wave (mmWave) wireless systems with large antenna arrays. By
exploiting the inherent mmWave channel sparsity, we propose a novel
simultaneous-estimation with iterative fountain training (SWIFT) framework, in
which the average number of channel measurements is adapted to various channel
conditions. To this end, the base station (BS) and each user continue to
measure the channel with a random subset of transmit/receive beamforming
directions until the channel estimate converges. We formulate the channel
estimation process as a compressed sensing problem and apply a sparse
estimation approach to recover the virtual channel information. As SWIFT does
not adapt the BS's transmitting beams to any single user, we are able to
estimate all user channels simultaneously. Simulation results show that SWIFT
can significantly outperform existing random-beamforming based approaches that
use a fixed number of measurements, over a range of signal-to-noise ratios and
channel coherence times.


title:
Experimental measurement-device-independent quantum random number
  generation

abstract:
  The randomness from a quantum random number generator (QRNG) relies on the
accurate characterization of its devices. However, device imperfections and
inaccurate characterizations can result in wrong entropy estimation and bias in
practice, which highly affects the genuine randomness generation and may even
induce the disappearance of quantum randomness in an extreme case. Here we
experimentally demonstrate a measurement-device-independent (MDI) QRNG based on
time-bin encoding to achieve certified quantum randomness even when the
measurement devices are uncharacterized and untrusted. The MDI-QRNG is randomly
switched between the regular randomness generation mode and a test mode, in
which four quantum states are randomly prepared to perform measurement
tomography in real-time. With a clock rate of 25 MHz, the MDI-QRNG generates a
final random bit rate of 5.7 Kbps. Such implementation with an all-fiber setup
provides an approach to construct a fully-integrated MDI-QRNG with trusted but
error-prone devices in practice.


title:
On the Silicate Crystallinities of Oxygen-Rich Evolved Stars and Their
  Mass Loss Rates

abstract:
  For decades ever since the early detection in the 1990s of the emission
spectral features of crystalline silicates in oxygen-rich evolved stars, there
is a long-standing debate on whether the crystallinity of the silicate dust
correlates with the stellar mass loss rate. To investigate the relation between
the silicate crystallinities and the mass loss rates of evolved stars, we carry
out a detailed analysis of 28 nearby oxygen-rich stars. We derive the mass loss
rates of these sources by modeling their spectral energy distributions from the
optical to the far infrared. Unlike previous studies in which the silicate
crystallinity was often measured in terms of the crystalline-to-amorphous
silicate mass ratio, we characterize the silicate crystallinities of these
sources with the flux ratios of the emission features of crystalline silicates
to that of amorphous silicates. This does not require the knowledge of the
silicate dust temperatures which are the major source of uncertainties in
estimating the crystalline-to-amorphous silicate mass ratio. With a Pearson
correlation coefficient of ~0.24, we find that the silicate crystallinities and
the mass loss rates of these sources are not correlated. This supports the
earlier findings that the dust shells of low mass-loss rate stars can contain a
significant fraction of crystalline silicates without showing the
characteristic features in their emission spectra.


title: Signal Manifestation Trade-offs in Incoherent Feed-Forward Loops

abstract:
  Signal processing in biological systems is delicately executed by specialised
networks, which are modular assemblies of network motifs. The motifs are
independently functional circuits found in enormous numbers in any living cell.
A very common network motif is the feed-forward loop (FFL), which regulates a
downstream node by an upstream one in a direct and an indirect way within the
network. If the direct and indirect regulations go antagonistic, the motif is
known as an incoherent FFL (ICFFL). The current study is aimed at exploring the
reason for the variation in the evolutionary selection of the four types of
ICFFLs. As comparative measures, I compute sensitivity amplification,
adaptation precision and efficiency from the temporal dynamics and mutual
information between the input-output nodes of the motifs at steady state. The
ICFFL II performs very efficiently in adaptation but poor in information
processing. On the other hand, ICFFL I and III are better in information
transmission compared to adaptation efficiency. Which is the fittest among them
under the pressure of natural selection? To sort out this puzzle, I take help
from the multi-objective Pareto efficiency. The results, found in the Pareto
task space, are in good agreement with the reported abundance level of all the
types in eukaryotes as well as prokaryotes.


title: One-point theta functions for vertex operator algebras

abstract:
  One-point theta functions for modules of vertex operator algebras (VOAs) are
defined and studied. These functions are a generalization of the character
theta functions studied by Miyamoto and are deviations of the classical
one-point functions for modules of a VOA. Transformation laws with respect to
the group $\operatorname{SL}_2(\mathbb{Z})$ are established.


title:
Fission barriers of two odd-neutron actinide nuclei taking into account
  the time-reversal symmetry breaking at the mean-field level

abstract:
  Background: Fission barriers of actinide nuclei have been mostly and for long
been microscopi- cally calculated for even-even fissioning systems.
Calculations in the case of odd nuclei have been performed merely within a
so-called equal-filling approximation (EFA) as opposed to an approach taking
explicitly into account the time reversal breaking properties at the mean field
level- and for only one single-particle configuration.
  Purpose: We study the dependence of the fission barriers on various relevant
configurations (e.g. to evaluate the so-called specialization energy). Besides,
we want to assess the relevance as a func- tion of the deformation of the EFA
approach which has been already found out at ground state deformation.
  Methods: Calculations within the Hartree-Fock plus BCS with self-consistent
particle blocking have been performed using the SkM* Skyrme effective
interaction in the particle-hole channel and a seniority force in the
particle-particle channel. Axial symmetry has been imposed throughout the whole
fission path while the intrinsic parity symmetry has been allowed to be broken
in the outer fission barrier region.
  Results: Potential energy curves have been determined for six different
configurations in U-235 and four in Pu-239. Inner and outer fission barriers
have been calculated along with some spectroscopic properties in the fission
isomeric well. These results have been compared with available data. The
influence of time-reversal breaking mean fields on the solutions has been
investigated.
  Conclusions: A sizeable configuration dependence of the fission barrier
(width and height) has been demonstrated. A reasonable agreement with available
systematic evaluations of fission barrier heights has been found. The EFA
approach has been validated at the large elongations occurring at the outer
barrier region.


title: Low-dimensional gap plasmons for enhanced light-graphene interactions

abstract:
  Graphene plasmonics has become a highlighted research area due to the
outstanding properties of deep-subwavelength plasmon excitation, long
relaxation time, and electro-optical tunability. Although the giant
conductivity of a graphene layer enables the low-dimensional confinement of
light, the atomic scale of the layer thickness is severely mismatched with
optical mode sizes, which impedes the efficient tuning of graphene plasmon
modes from the degraded light-graphene overlap. Inspired by gap plasmon modes
in noble metals, here we propose low-dimensional graphene gap plasmon waves for
large light-graphene overlap factor. We show that gap plasmon waves exhibit
superior in-plane and out-of-plane field concentrations on graphene compared to
those of edge or wire-like graphene plasmons. By adjusting the chemical
property of the graphene layer, efficient and linear modulation of graphene gap
plasmon modes is also achieved. Our results provide potential opportunities to
low-dimensional graphene plasmonic devices with strong tunability.


title: A Multi-Pass Approach to Large-Scale Connectomics

abstract:
  The field of connectomics faces unprecedented "big data" challenges. To
reconstruct neuronal connectivity, automated pixel-level segmentation is
required for petabytes of streaming electron microscopy data. Existing
algorithms provide relatively good accuracy but are unacceptably slow, and
would require years to extract connectivity graphs from even a single cubic
millimeter of neural tissue. Here we present a viable real-time solution, a
multi-pass pipeline optimized for shared-memory multicore systems, capable of
processing data at near the terabyte-per-hour pace of multi-beam electron
microscopes. The pipeline makes an initial fast-pass over the data, and then
makes a second slow-pass to iteratively correct errors in the output of the
fast-pass. We demonstrate the accuracy of a sparse slow-pass reconstruction
algorithm and suggest new methods for detecting morphological errors. Our
fast-pass approach provided many algorithmic challenges, including the design
and implementation of novel shallow convolutional neural nets and the
parallelization of watershed and object-merging techniques. We use it to
reconstruct, from image stack to skeletons, the full dataset of Kasthuri et al.
(463 GB capturing 120,000 cubic microns) in a matter of hours on a single
multicore machine rather than the weeks it has taken in the past on much larger
distributed systems.


title:
Finiteness Theorems for Products and Symmetric Products of Hyperbolic
  Riemann Surfaces

abstract:
  We prove that if $X = X_1 \times \dots \times X_n$ is a product of hyperbolic
Riemann surfaces of finite type and $Y = \Omega/\Gamma$ is a complex manifold,
where $\Omega$ is a bounded simply-connected domain in $\mathbb{C}^m$, then the
space of dominant holomorphic mappings from $X$ to $Y$ is a finite set. As
corollaries, we obtain the finiteness of the space of dominant holomorphic
mappings into products and symmetric products of hyperbolic Riemann surfaces.


title: Subsampled Phase Retrieval for On-chip Lensless Holographic Video

abstract:
  On-chip holographic video is a convenient way to monitor biological samples
simultaneously at high spatial resolution and over a wide field-of-view.
However, due to the limited readout rate of digital detector arrays, one often
faces a tradeoff between the per-frame pixel count and frame rate of the
captured video. In this report, we propose a subsampled phase retrieval (SPR)
algorithm to overcome the spatial-temporal trade-off in holographic video.
Compared to traditional phase retrieval approaches, our SPR algorithm uses over
an order of magnitude less pixel measurements while maintaining suitable
reconstruction quality. We use an on-chip holographic video setup with pixel
sub-sampling to experimentally demonstrate a factor of 5.5 increase in sensor
frame rate while monitoring the in vivo movement of Peranema microorganisms.


title: Renormalization of fermion velocity in finite temperature QED_{3}

abstract:
  At zero temperature, the Lorentz invariance is strictly preserved in
three-dimensional quantum electrodynamics. This property ensures that the
velocity of massless fermions is not renormalized by the gauge interaction. At
finite temperature, however, the Lorentz invariance is explicitly broken by the
thermal fluctuation. The longitudinal component of gauge interaction becomes
short-ranged due to thermal screening, whereas the transverse component remains
long-ranged because of local gauge invariance. The transverse gauge interaction
leads to singular corrections to the fermion self-energy and thus results in an
unusual renormalization of the fermion velocity. We calculate the renormalized
fermion velocity $v^R(p_0,\mathbf{p},T)$ by employing a renormalization group
analysis, and discuss the influence of the anomalous dimension $\eta_n$ on the
fermion specific heat.


title: Preparation of a single-photon dark state in a chiral quantum system

abstract:
  We examine conditions under which an open quantum system composed of a driven
degenerated parametric oscillator cavity and a driven two-level atom coupled to
a waveguide could decay to a pure dark state rather than the expected mixed
state. The calculations are carried out analytically in a low dimensional
Hilbert space truncated at the double-excitation states of the combined system.
The validity of the truncation is confirmed by the exact numerical analysis. It
is found that one way to produce the pure state is to chirally couple the
cavity and the atom to the waveguide. Another way to produce the pure state is
to drive the cavity and the atom with unequal detunings. In both cases, if the
driving fields are weak, the produced state is a coherent superposition of only
the single-excitation and ground states of the combined system. In addition, we
have found a direct correspondence between the generation of the dark state and
the photon blockade effect. In other words, the generation of the dark state
acts as a blockade to the number of photons so that only a single photon can be
present in the cavity. We investigate the normalized second-order correlation
function of the cavity field and find that the conditions under which the
correlation function vanishes coincide with the conditions for the creation of
the pure dark state. This system is, therefore, suggested as an alternative
scheme for the generation of single-photon states.


title: The pluriharmonic Hardy space and Toeplitz Operators

abstract:
  Compared with harmonic Bergman spaces, this paper introduces a new function
space which is called the pluriharmonic Hardy space $h^{2}(\mathbb{T}^{2})$. We
character (semi-) commuting Toeplitz operators on $h^{2}(\mathbb{T}^{2})$ with
bounded pluriharmonic symbols. Interestingly, these results are quite different
from the corresponding properties of Toeplitz operators on Hardy spaces,
Bergman spaces and harmonic Bergman spaces. Our method for Toeplitz operators
on $h^{2}(\mathbb{T}^{2})$ gives new insight into the study of commuting
Toeplitz operators on harmonic Bergman spaces.


title: Rate-cost tradeoffs in control

abstract:
  Consider a control problem with a communication channel connecting the
observer of a linear stochastic system to the controller. The goal of the
controller is to minimize a quadratic cost function in the state variables and
control signal, known as the linear quadratic regulator (LQR). We study the
fundamental tradeoff between the communication rate $r$ bits/sec and the
expected cost $b$. We obtain a lower bound on a certain rate-cost function,
which quantifies the minimum directed mutual information between the channel
input and output that is compatible with a target LQR cost. The rate-cost
function has operational significance in multiple scenarios of interest: among
others, it allows us to lower-bound the minimum communication rate for fixed
and variable length quantization, and for control over noisy channels. We
derive an explicit lower bound to the rate-cost function, which applies to the
vector, non-Gaussian, and partially observed systems, thereby extending and
generalizing an earlier explicit expression for the scalar Gaussian system, due
to Tatikonda el al. The bound applies as long as the differential entropy of
the system noise is not $-\infty$. It can be closely approached by a simple
lattice quantization scheme that only quantizes the innovation, that is, the
difference between the controller's belief about the current state and the true
state. Via a separation principle between control and communication, similar
results hold for causal lossy compression of additive noise Markov sources.
Apart from standard dynamic programming arguments, our technical approach
leverages the Shannon lower bound, develops new estimates for data compression
with coding memory, and uses some recent results on high resolution
variable-length vector quantization to prove that the new converse bounds are
tight.


title: Spectral compression of single-photon-level laser pulse

abstract:
  We experimentally demonstrate that the bandwidth of single photons laser
pulse is compressed by a factor of 58 in a periodically poled lithium niobate
(PPLN) waveguide chip. A chirped single photons laser pulse and an oppositely
chirped classical laser pulse are employed to produce a narrowband single
photon pulse with new frequency through sum-frequency generation. In our
experiment, the frequency and bandwidth of single photons at 1550 nm are
simultaneously converted. Our results mark a critical step towards the
realization of coherent photonic interface between quantum communication at
1550 nm and quantum memory in the near-visible window.


title: Rate-cost tradeoffs in control. Part II: achievable scheme

abstract:
  Consider a distributed control problem with a communication channel
connecting the observer of a linear stochastic system to the controller. The
goal of the controller is to minimize a quadratic cost function in the state
variables and control signal, known as the linear quadratic regulator (LQR). We
study the fundamental tradeoff between the communication rate r bits/sec and
the limsup of the expected cost b. In the companion paper, which can be read
independently of the current one, we show a lower bound on a certain cost
function, which quantifies the minimum mutual information between the channel
input and output, given the past, that is compatible with a target LQR cost.
The bound applies as long as the system noise has a probability density
function, and it holds for a general class of codes that can take full
advantage of the memory of the data observed so far and that are not
constrained to have any particular structure. In this paper, we prove that the
bound can be approached by a simple variable-length lattice quantization
scheme, as long as the system noise satisfies a smoothness condition. The
quantization scheme only quantizes the innovation, that is, the difference
between the controller's belief about the current state and the encoder's state
estimate. Our proof technique leverages some recent results on nonasymptotic
high resolution vector quantization.


title: Inverse Problems for the Heat Equation with Memory

abstract:
  We study inverse boundary problems for a one dimensional linear
integro-differential equation of the Gurtin--Pipkin type with the
Dirichlet-to-Neumann map as the inverse data. Under natural conditions on the
kernel of the integral operator, we give the explicit formula for the solution
of the problem with the observation on the semiaxis $t>0.$
  For the observation on finite time interval, we prove the uniqueness result,
which is similar to the local Borg--Marchenko theorem for the Schr\"odinger
equation.


title: Predictive Business Process Monitoring with LSTM Neural Networks

abstract:
  Predictive business process monitoring methods exploit logs of completed
cases of a process in order to make predictions about running cases thereof.
Existing methods in this space are tailor-made for specific prediction tasks.
Moreover, their relative accuracy is highly sensitive to the dataset at hand,
thus requiring users to engage in trial-and-error and tuning when applying them
in a specific setting. This paper investigates Long Short-Term Memory (LSTM)
neural networks as an approach to build consistently accurate models for a wide
range of predictive process monitoring tasks. First, we show that LSTMs
outperform existing techniques to predict the next event of a running case and
its timestamp. Next, we show how to use models for predicting the next task in
order to predict the full continuation of a running case. Finally, we apply the
same approach to predict the remaining time, and show that this approach
outperforms existing tailor-made methods.


title: Universality of the unitary Fermi gas: A few-body perspective

abstract:
  We revisit the properties of the two-component Fermi gas with short-range
interactions in three dimensions, in the limit where the s-wave scattering
length diverges. Such a unitary Fermi gas possesses universal thermodynamic and
dynamical observables that are independent of any interaction length scale.
Focusing on trapped systems of N fermions, where N$\leq10$, we investigate how
well we can determine the zero-temperature behavior of the many-body system
from published few-body data on the ground-state energy and the contact. For
the unpolarized case, we find that the Bertsch parameters extracted from
trapped few-body systems all lie within 15% of the established value.
Furthermore, the few-body values for the contact are well within the range of
values determined in the literature for the many-body system. In the limit of
large spin polarization, we obtain a similar accuracy for the polaron energy,
and we estimate the polaron's effective mass from the dependence of its energy
on N. We also compute an upper bound for the squared wave-function overlap
between the unitary Fermi system and the non-interacting ground state, both for
the trapped and uniform cases. This allows us to prove that the trapped
unpolarised ground state at unitarity has zero overlap with its non-interacting
counterpart in the many-body limit N$\to \infty$.


title: A remark on the construction of centric linking systems

abstract:
  We give examples to show that it is not in general possible to prove the
existence and uniqueness of centric linking systems associated to a given
fusion system inductively by adding one conjugacy class at a time to the
categories. This helps to explain why it was so difficult to prove that these
categories always exist, and also helps to motivate the procedure used by
Chermak when he did prove it.


title:
Approximation Algorithms for Optimization of Real-Valued General
  Conjugate Complex Forms

abstract:
  Complex polynomial optimization has recently gained more and more attention
in both theory and practice. In this paper, we study the optimization of a
real-valued general conjugate complex form over various popular constraint sets
including the m-th roots of complex unity, the complex unit circle, and the
complex unit sphere. A real-valued general conjugate complex form is a
homogenous polynomial function of complex variables as well as their
conjugates, and always takes real values. General conjugate form optimization
is a wide class of complex polynomial optimization models, which include many
homogenous polynomial optimization in the real domain with either discrete or
continuous variables, and Hermitian quadratic form optimization as well as its
higher degree extensions. All the problems under consideration are NP-hard in
general and we focus on polynomial-time approximation algorithms with
worst-case performance ratios. These approximation ratios improve previous
results when restricting our problems to some special classes of complex
polynomial optimization, and improve or equate previous results when
restricting our problems to some special classes of polynomial optimization in
the real domain. These algorithms are based on tensor relaxation and random
sampling. Our novel technical contributions are to establish the first set of
probability lower bounds for random sampling over the m-th root of unity, the
complex unit circle, and the complex unit sphere, and propose the first
polarization formula linking general conjugate forms and complex multilinear
forms.


title:
Intertwining operators and vector-valued modular forms for minimal
  models

abstract:
  Using the language of vertex operator algebras (VOAs) and vector-valued
modular forms we study the modular group representations and spaces of 1-point
functions associated to intertwining operators for Virasoro minimal model VOAs.
We examine all representations of dimension less than four associated to
irreducible modules for minimal models, and determine when the kernel of these
representations is a congruence or noncongruence subgroup of the modular group.
Arithmetic criteria are given on the indexing of the irreducible modules for
minimal models that imply the associated modular group representation has a
noncongruence kernel, independent of the dimension of the representation. The
algebraic structure of the spaces of 1-point functions for intertwining
operators is also studied, via a comparison with the associated spaces of
holomorphic vector-valued modular forms.


title:
Discrete and Continuous ambush games: optimal policies and approximate
  solutions

abstract:
  We consider an autonomous navigation problem, whereby a traveler aims at
traversing an environment in which an adversary tries to set an ambush. A two
players zero sum game is introduced. Players' strategies are computed as random
path distributions, a realization of which is the path chosen by the traveler.
A parallel is drawn between the discrete problem, where the traveler moves on a
network, and the continuous problem, where the traveler moves in the plane.
Analytical optimal policies are derived. Using assumptions from the Minimal Cut
- Maximal Flow literature, the optimal value of the game is shown to be related
to the maximum flow on the environment in both the discrete and the continuous
cases, when the reward function for the ambusher is uniform. A linear program
is introduced that allows for the computation of optimal policies, compatible
with non-uniform reward functions. In order to relax the assumptions for the
computation of the players' optimal strategies of the continuous game, a
network is created, inspired by recently introduced sampling based motion
planning techniques, and the linear program is adapted for continuous
constraints.


title: Mode Regularized Generative Adversarial Networks

abstract:
  Although Generative Adversarial Networks achieve state-of-the-art results on
a variety of generative tasks, they are regarded as highly unstable and prone
to miss modes. We argue that these bad behaviors of GANs are due to the very
particular functional shape of the trained discriminators in high dimensional
spaces, which can easily make training stuck or push probability mass in the
wrong direction, towards that of higher concentration than that of the data
generating distribution. We introduce several ways of regularizing the
objective, which can dramatically stabilize the training of GAN models. We also
show that our regularizers can help the fair distribution of probability mass
across the modes of the data generating distribution, during the early phases
of training and thus providing a unified solution to the missing modes problem.


title:
Effects of a small magnetic field on homoclinic bifurcations in a
  low-Prandtl-number fluid

abstract:
  Effects of a uniform magnetic field on homoclinic bifurcations in
Rayleigh-B\'{e}nard convection in a fluid of Prandtl number $Pr = 0.01$ are
investigated using direct numerical simulations (DNS). A uniform magnetic field
is applied either in the vertical or in the horizontal direction. For a weak
vertical magnetic field, the possibilities of both forward and backward
homoclinic bifurcations are observed leading to a spontaneous merging of two
limit cycles into one as well as a spontaneous breaking of a limit cycle into
two for lower values of the Chandrasekhar's number ($Q\leq 5$). A slightly
stronger magnetic field makes the convective flow time independent giving the
possibility of stationary patterns at the secondary instability. For horizontal
magnetic field, the $x\leftrightharpoons y$ symmetry is destroyed and neither a
homoclinic gluing nor a homoclinic breaking is observed. Two low-dimensional
models are also constructed: one for a weak vertical magnetic field and another
for a weak horizontal magnetic field. The models qualitatively capture the
features observed in DNS and help understanding the unfolding of bifurcations
close to the onset of magnetoconvection.


title:
Scaling and universality in the phase diagram of the 2D Blume-Capel
  model

abstract:
  We review the pertinent features of the phase diagram of the zero-field
Blume-Capel model, focusing on the aspects of transition order, finite-size
scaling and universality. In particular, we employ a range of Monte Carlo
simulation methods to study the 2D spin-1 Blume-Capel model on the square
lattice to investigate the behavior in the vicinity of the first-order and
second-order regimes of the ferromagnet-paramagnet phase boundary,
respectively. To achieve high-precision results, we utilize a combination of
(i) a parallel version of the multicanonical algorithm and (ii) a hybrid
updating scheme combining Metropolis and generalized Wolff cluster moves. These
techniques are combined to study for the first time the correlation length of
the model, using its scaling in the regime of second-order transitions to
illustrate universality through the observed identity of the limiting value of
$\xi/L$ with the exactly known result for the Ising universality class.


title:
Radiative corrections to elastic proton-electron scattering measured in
  coincidence

abstract:
  The differential cross section for elastic scattering of protons on electrons
at rest is calculated taking into account the QED radiative corrections to the
leptonic part of interaction. These model-independent radiative corrections
arise due to emission of the virtual and real soft and hard photons as well as
to vacuum polarization. We analyze an experimental setup when both the final
particles are recorded in coincidence and their energies are determined within
some uncertainties. The kinematics, the cross section, and the radiative
corrections are calculated and numerical results are presented.


title:
Kossel interferences of proton-induced X-ray emission lines in periodic
  multilayers

abstract:
  The Kossel interferences generated by characteristic x-ray lines produced
inside a periodic multilayer have been observed upon proton irradiation, by
submitting a Cr/B4C/Sc multilayer stack to 2 MeV protons and observing the
intensity of the Sc and Cr K$\alpha$ characteristic emissions as a function of
the detection angle. When this angle is close to the Bragg angle corresponding
to the emission wavelength and period of the multilayer, an oscillation of the
measured intensity is detected. The results are in good agreement with a model
based on the reciprocity theorem. The combination of the Kossel measurements
and their simulation, will be a useful tool to obtain a good description of the
multilayer stack and thus to study nanometer-thick layers and their interfaces.


title:
Learning Localized Geometric Features Using 3D-CNN: An Application to
  Manufacturability Analysis of Drilled Holes

abstract:
  3D convolutional neural networks (3D-CNN) have been used for object
recognition based on the voxelized shape of an object. In this paper, we
present a 3D-CNN based method to learn distinct local geometric features of
interest within an object. In this context, the voxelized representation may
not be sufficient to capture the distinguishing information about such local
features. To enable efficient learning, we augment the voxel data with surface
normals of the object boundary. We then train a 3D-CNN with this augmented data
and identify the local features critical for decision-making using 3D
gradient-weighted class activation maps. An application of this feature
identification framework is to recognize difficult-to-manufacture drilled hole
features in a complex CAD geometry. The framework can be extended to identify
difficult-to-manufacture features at multiple spatial scales leading to a
real-time decision support system for design for manufacturability.


title: Imaginaries in separably closed valued fields

abstract:
  We show that separably closed valued fields of finite imperfection degree
(either with lambda-functions or commuting Hasse derivations) eliminate
imaginaries in the geometric language. We then use this classification of
interpretable sets to study stably dominated types in those structures. We show
that separably closed valued fields of finite imperfection degree are
metastable and that the space of stably dominated types is strict
pro-definable.


title: Topological frequency conversion in strongly driven quantum systems

abstract:
  When a physical system is subjected to a strong external multi-frequency
drive, its dynamics can be conveniently represented in the multi-dimensional
Floquet lattice. The number of the Floquet lattice dimensions equals the number
of {\em irrationally}-related drive frequencies, and the evolution occurs in
response to a built-in effective "electric" field, whose components are
proportional to the corresponding drive frequencies. The mapping allows to
engineer and study temporal analogs of many real-space phenomena. Here we focus
on the specific example of a two-level system under two-frequency drive that
induces topologically nontrivial band structure in the 2D Floquet space. The
observable consequence of such construction is quantized pumping of energy
between the sources with frequencies $\omega_1$ and $\omega_2$. When the system
is initialized into a Floquet band with the Chern number $C$, the pumping
occurs at the rate $P_{12} = -P_{21}= (C/2\pi)\hbar \omega_1\omega_2$, an exact
counterpart of the transverse current in a conventional topological insulator.


title:
A $q$-series identity via the $\mathfrak{sl}_3$ colored Jones
  polynomials for the $(2,2m)$-torus link

abstract:
  The colored Jones polynomial is a $q$-polynomial invariant of links colored
by irreducible representations of a simple Lie algebra. A $q$-series called a
tail is obtained as the limit of the $\mathfrak{sl}_2$ colored Jones
polynomials $\{J_n(K;q)\}_n$ for some link $K$, for example, an alternating
link. For the $\mathfrak{sl}_3$ colored Jones polynomials, the existence of a
tail is unknown. We give two explicit formulas of the tail of the
$\mathfrak{sl}_3$ colored Jones polynomials colored by $(n,0)$ for the
$(2,2m)$-torus link. These two expressions of the tail provide an identity of
$q$-series. This is a knot-theoretical generalization of the Andrews-Gordon
identities for the Ramanujan false theta function.


title: A Unified Linear Precoding Design for Multi-user MIMO Systems

abstract:
  We address the problem of the bit error rate (BER) performance gap between
the sub-optimal and optimal linear precoder (LP) for a multiuser (MU) multiple
input and multiple output (MIMO) broadcast systems in this paper. Particularly,
mobile users suffer noise enhancement effect due to a sub-optimal LP that can
be suppressed by an optimal LP matrix. A sub-optimal LP matrix such as a linear
zero-forcing (LZF) precoder performs in high signal to noise ratio (SNR) regime
only, in contrast, an optimal precoder for instance a linear minimum
mean-square-error (LMMSE) precoder outperforms in both low and high SNR
scenarios. These kinds of precoder illustrates the BER gap distance at least
0.1 when it is used in itself in a MU MIMO systems. Thus, we propose and design
a unified linear precoding (ULP) matrix using a precoding selection technique
that combines the sub-optimal and optimal LP matrix for a multi-user MIMO
systems to ensure zero BER performance gap in this paper. The numerical results
show that our proposed ULP technique offers significant performance in both low
and high SNR scenarios.


title:
Anharmonic resonance absorption of short laser pulses in clusters: A
  molecular dynamics simulation study

abstract:
  Linear resonance (LR) absorption of an intense 800~nm laser light in a
nano-cluster requires a long laser pulse > 100~fs when Mie-plasma frequency
($\omegaMie$) of electrons in the expanding cluster matches the laser
frequency~($\omega$). For a short duration of the pulse the condition for LR is
not satisfied. In this case, it was shown by a model and particle-in-cell (PIC)
simulations [Phys. Rev. Lett. 96, 123401 (2006)] that electrons absorb laser
energy by anharmonic resonance (AHR) when the position-dependent frequency
$\Omega[r(t)]$ of an electron in the self-consistent anharmonic potential of
the cluster satisfies $\Omega[r(t)]=\omega$. However, AHR remains to be a
debate and still obscure in multi-particle plasma simulations. Here, we
identify AHR mechanism in a laser driven cluster using molecular dynamics (MD)
simulations. By analyzing the trajectory of each MD electron and extracting its
$\Omega[r(t)]$ in the self-generated anharmonic plasma potential it is found
that electron is outer ionized {\em only} when AHR is met. An anharmonic
oscillator model, introduced here, brings out most of the features of MD
electrons while passing the AHR. Thus, we not only bridge the gap between PIC
simulations, analytical models and MD calculations for the first time but also
unequivocally prove that AHR processes is a universal dominant collisionless
mechanism of absorption in the short pulse regime or in the early time of
longer pulses in clusters.


title: Challenges faced by current Galactic planetary nebula surveys

abstract:
  Determining the demographics of the Galactic planetary nebula (PN) population
is an important goal to further our understanding of this intriguing phase of
stellar evolution. The Galactic population has more than doubled in number over
the last 15 years, particularly from narrowband \ha\ surveys along the plane.
In this review I will summarise these results, with emphasis on the time
interval since the last IAU Symposium. These primarily optical surveys are not
without their limitations and new surveys for PNe in the infrared similarly
face a number of challenges. I will discuss the need for multi-wavelength
approaches to discovery and analysis. The desire to have accurate
volume-limited samples of Galactic PNe at our disposal is emphasised, which
will be impacted with new data from the Gaia satellite mission. We need robust
surveys of PNe and their central stars, especially volume-limited surveys, in
order to clarify and quantify their evolutionary pathways.


title:
Null-recurrence and transience of random difference equations in the
  contractive case

abstract:
  Given a sequence $(M_{k}, Q_{k})_{k\ge 1}$ of independent, identically
distributed ran\-dom vectors with nonnegative components, we consider the
recursive Markov chain $(X_{n})_{n\ge 0}$, defined by the random difference
equation $X_{n}=M_{n}X_{n-1}+Q_{n}$ for $n\ge 1$, where $X_{0}$ is independent
of $(M_{k}, Q_{k})_{k\ge 1}$. Criteria for the null-recurrence/transience are
provided in the situation where $(X_{n})_{n\ge 0}$ is contractive in the sense
that $M_{1}\cdot\ldots\cdot M_{n}\to 0$ a.s., yet occasional large values of
the $Q_{n}$ overcompensate the contractive behavior so that positive recurrence
fails to hold. We also investigate the attractor set of $(X_{n})_{n\ge 0}$
under the sole assumption that this chain is locally contractive and recurrent.