title: Contextual Decision Processes with Low Bellman Rank are PAC-Learnable

abstract:
  This paper studies systematic exploration for reinforcement learning with
rich observations and function approximation. We introduce a new model called
contextual decision processes, that unifies and generalizes most prior
settings. Our first contribution is a complexity measure, the Bellman rank,
that we show enables tractable learning of near-optimal behavior in these
processes and is naturally small for many well-studied reinforcement learning
settings. Our second contribution is a new reinforcement learning algorithm
that engages in systematic exploration to learn contextual decision processes
with low Bellman rank. Our algorithm provably learns near-optimal behavior with
a number of samples that is polynomial in all relevant parameters but
independent of the number of unique observations. The approach uses Bellman
error minimization with optimistic exploration and provides new insights into
efficient exploration for reinforcement learning with function approximation.


title:
Phased LSTM: Accelerating Recurrent Network Training for Long or
  Event-based Sequences

abstract:
  Recurrent Neural Networks (RNNs) have become the state-of-the-art choice for
extracting patterns from temporal sequences. However, current RNN models are
ill-suited to process irregularly sampled data triggered by events generated in
continuous time by sensors or other neurons. Such data can occur, for example,
when the input comes from novel event-driven artificial sensors that generate
sparse, asynchronous streams of events or from multiple conventional sensors
with different update intervals. In this work, we introduce the Phased LSTM
model, which extends the LSTM unit by adding a new time gate. This gate is
controlled by a parametrized oscillation with a frequency range that produces
updates of the memory cell only during a small percentage of the cycle. Even
with the sparse updates imposed by the oscillation, the Phased LSTM network
achieves faster convergence than regular LSTMs on tasks which require learning
of long sequences. The model naturally integrates inputs from sensors of
arbitrary sampling rates, thereby opening new areas of investigation for
processing asynchronous sensory events that carry timing information. It also
greatly improves the performance of LSTMs in standard RNN applications, and
does so with an order-of-magnitude fewer computes at runtime.


title:
REFOCUS: Current & Future Search Interface Requirements for
  German-speaking Users

abstract:
  While smartphones are widely used for web browsing, also other novel devices
like Smart TVs become increasingly popular. Yet, current interfaces do not
cater for the newly available devices beyond touch and small screens, if at all
for the latter. Particularly search engines--today's entry points of the
WWW--must ensure their interfaces are easy to use on any web-enabled device. We
report on a survey that investigated (1) users' perception and usage of current
search interfaces, and (2) their expectations towards current and future search
interfaces. Users are mostly satisfied with desktop and mobile search, but seem
to be skeptical towards web search with novel devices and input modalities.
Hence, we derive REFOCUS--a novel set of requirements for current and future
search interfaces, which shall address the demand for improvement of novel web
search and has been validated by 12 dedicated experts.


title:
Influence of a Pseudo Aharonov-Bohm field on the quantum Hall effect in
  Graphene

abstract:
  The effect of an Aharonov-Bohm (AB) pseudo magnetic field on a two
dimensional electron gas in graphene is investigated. We consider it modeled as
in the usual AB effect but since such pseudo field is supposed to be induced by
elastic deformations, the quantization of the field flux is abandoned. For
certain constraints on the orbital angular momentum eigenvalues allowed for the
system, we can observe the zero Landau level failing to develop, due to the
degeneracy related to the Dirac valleys $K$ and $K^\prime$ which is broken. For
integer values of the pseudo AB flux, the actual quantum Hall effect is
preserved. Obtaining the Hall conductivity by summing over all orbital angular
momentum eigenvalues, the zero Landau levels is recovered. Since our problem is
closed related to the case where topological defects on a graphene sheet are
present, the questions posed here are helpful if one is interested to probe the
effects of a singular curvature in these systems.


title: Finding Street Gang Members on Twitter

abstract:
  Most street gang members use Twitter to intimidate others, to present
outrageous images and statements to the world, and to share recent illegal
activities. Their tweets may thus be useful to law enforcement agencies to
discover clues about recent crimes or to anticipate ones that may occur.
Finding these posts, however, requires a method to discover gang member Twitter
profiles. This is a challenging task since gang members represent a very small
population of the 320 million Twitter users. This paper studies the problem of
automatically finding gang members on Twitter. It outlines a process to curate
one of the largest sets of verifiable gang member profiles that have ever been
studied. A review of these profiles establishes differences in the language,
images, YouTube links, and emojis gang members use compared to the rest of the
Twitter population. Features from this review are used to train a series of
supervised classifiers. Our classifier achieves a promising F1 score with a low
false positive rate.


title:
Moduli spaces of invariant metrics of positive scalar curvature on
  quasitoric manifolds

abstract:
  We show that the higher homotopy groups of the moduli space of
torus-invariant positive scalar curvature metrics on certain quasitoric
manifolds are non-trivial.


title: Equation of state in (2+1)-flavor QCD with gradient flow

abstract:
  The energy-momentum tensor and equation of state are studied in
finite-temperature (2+1)-flavor QCD with improved Wilson quarks using the
method proposed by Makino and Suzuki based on the gradient flow. We find that
the results of the gradient flow are consistent with the previous results using
the $T$-integration method at $T \mathrel{\rlap{\raise 0.511ex
\hbox{$<$}}{\lower 0.511ex \hbox{$\sim$}}} 280$ MeV ($N_t\mathrel{\rlap{\raise
0.511ex \hbox{$>$}}{\lower 0.511ex \hbox{$\sim$}}}10$), while a disagreement is
found at $T \mathrel{\rlap{\raise 0.511ex \hbox{$>$}}{\lower 0.511ex
\hbox{$\sim$}}} 350$ MeV ($N_t \mathrel{\rlap{\raise 0.511ex \hbox{$<$}}{\lower
0.511ex \hbox{$\sim$}}} 8$) presumably due to the small-$N_t$ lattice artifact.
We also report on the results on the renormalized chiral condensate and its
disconnected susceptibility using the method of Hieda and Suzuki. The results
show a clear signal of the expected chiral restoration crossover even with
Wilson-type quarks which violate the chiral symmetry explicitly.


title: Multifractal cross wavelet analysis

abstract:
  Complex systems are composed of mutually interacting components and the
output values of these components are usually long-range cross-correlated. We
propose a method to characterize the joint multifractal nature of such
long-range cross correlations based on wavelet analysis, termed multifractal
cross wavelet analysis (MFXWT). We assess the performance of the MFXWT method
by performing extensive numerical experiments on the dual binomial measures
with multifractal cross correlations and the bivariate fractional Brownian
motions (bFBMs) with monofractal cross correlations. For binomial multifractal
measures, the empirical joint multifractality of MFXWT is found to be in
approximate agreement with the theoretical formula. For bFBMs, MFXWT may
provide spurious multifractality because of the wide spanning range of the
multifractal spectrum. We also apply the MFXWT method to stock market indexes
and uncover intriguing joint multifractal nature in pairs of index returns and
volatilities.


title:
Multi-Camera Occlusion and Sudden-Appearance-Change Detection Using
  Hidden Markovian Chains

abstract:
  This paper was originally submitted to Xinova as a response to a Request for
Invention (RFI) on new event monitoring methods. In this paper, a new object
tracking algorithm using multiple cameras for surveillance applications is
proposed. The proposed system can detect sudden-appearance-changes and
occlusions using a hidden Markovian statistical model. The experimental results
confirm that our system detect the sudden-appearance changes and occlusions
reliably.


title: Broadband Polarizers Based on Graphene Metasurfaces

abstract:
  We present terahertz (THz) metasurfaces based on aligned rectangular graphene
patches placed on top of a dielectric layer to convert the transmitted linearly
polarized waves to circular or elliptical polarized radiation. Our results lead
to the design of an ultrathin broadband THz quarter-wave plate. In addition,
ultrathin metasurfaces based on arrays of L-shaped graphene periodic patches
are demonstrated to achieve broadband cross-polarization transformation in
reflection and transmission. The proposed metasurface designs have tunable
responses and are envisioned to become the building blocks of several
integrated THz systems.


title:
A Fast 3D Poisson Solver with Longitudinal Periodic and Transverse Open
  Boundary Conditions for Space-Charge Simulations

abstract:
  A three-dimensional (3D) Poisson solver with longitudinal periodic and
transverse open boundary conditions can have important applications in beam
physics of particle accelerators. In this paper, we present a fast efficient
method to solve the Poisson equation using a spectral finite-difference method.
This method uses a computational domain that contains the charged particle beam
only and has a computational complexity of $O(N_u(logN_{mode}))$, where $N_u$
is the total number of unknowns and $N_{mode}$ is the maximum number of
longitudinal or azimuthal modes. This saves both the computational time and the
memory usage by using an artificial boundary condition in a large extended
computational domain.


title: A classification of nullity classes in the derived category of a ring

abstract:
  For a commutative Noetherian ring $R$ with finite Krull dimension, we study
the nullity classes in $D^c_{fg}(R)$, the full triangulated subcategory
$D^c_{fg}(R)$ of the derived category $D(R)$ consisting of objects which can be
represented by cofibrant objects with each degree finitely generated. In the
light of perversity functions over the prime spectrum $\mathrm{Spec} R$, we
prove that there is a complete invariant of nullity classes thus that of aisles
(or equivalently, $t$-structures) in $D^c_{fg}(R)$.


title:
Excitation of H$_{2}^{+}$ with one-cycle laser pulses: Shaped
  post-laser-field electronic oscillations, generation of higher- and
  lower-order harmonics

abstract:
  Non Born-Oppenheimer quantum dynamics of H$_{2}^{+}$ excited by shaped
one-cycle laser pulses linearly polarized along the molecular axis have been
studied by the numerical solution of the time-dependent Schr\"odinger equation
within a %three-body three-dimensional model, including the internuclear
separation, $R$, and the electron coordinates $z$ and $\rho$. Laser carrier
frequencies corresponding to the wavelengths $\lambda_{l}=25$~nm through
$\lambda_{l}=400$~nm were used and the amplitudes of the pulses were chosen
such that the energy of H$_{2}^{+}$ was close to its dissociation threshold at
the end of any laser pulse applied. It is shown that there exists a
characteristic oscillation frequency $\omega_{\rm osc} \simeq 0.2265$~au
(corresponding to the period of $\tau_{\rm osc} \simeq 0.671$~fs and the
wavelength of $\lambda_{\rm osc} \simeq 200$~nm) that manifests itself as a
"carrier" frequency of temporally shaped oscillations of the time-dependent
expectation values $\langle z \rangle$ and $\langle \partial V/\partial z
\rangle$ that emerge at the ends of the laser pulses and exist on a timescale
of at least 50~fs. Time-dependent expectation values $\langle \rho \rangle$ and
$\langle \partial V/\partial \rho \rangle$ of the optically-passive degree of
freedom, $\rho$, demonstrate post-laser-field oscillations at two basic
frequencies $\omega^{\rho}_{1} \approx \omega_{\rm osc}$ and $\omega^{\rho}_{2}
\approx 2\omega_{\rm osc}$. Power spectra associated with the electronic motion
show higher- and lower-order harmonics with respect to the driving field.


title:
Spherically symmetric solution of the Weyl-Dirac theory of gravitation
  and possible influence of dark matter on the interplanetary spacecraft motion

abstract:
  The Poincare and Poincare-Weyl gauge theories of gravitation with Lagrangians
quadratic on curvature and torsion in post-Riemannian spaces with the Dirac
scalar field is discussed in a historical aspect. The various hypothesizes
concerning the models of a dark matter with the help of a scalar field are
considered. The new conformal Weyl-Dirac theory of gravitation is proposed,
which is a gravitational theory in Cartan-Weyl space-time with the Dirac scalar
field representing the dark matter model. A static spherically symmetric
solution of the field equations in vacuum for a central compact mass is
obtained as the metrics conformal to the Yilmaz-Rosen metrics. On the base of
this solution one considers a radial movement of an interplanetary spacecraft
starting from the Earth. Using the Newton approximation one obtains that the
asymptotic line-of-sight velocity in this case depends from the parameters of
the solution, and therefore one can obtain on basis of the observable data the
values of these parameters.


title: Partition-based Caching in Large-Scale SIC-Enabled Wireless Networks

abstract:
  Existing designs for content dissemination do not fully explore and exploit
potential caching and computation capabilities in advanced wireless networks.
In this paper, we propose two partition-based caching designs, i.e., a coded
caching design based on Random Linear Network Coding and an uncoded caching
design. We consider the analysis and optimization of the two caching designs in
a large-scale successive interference cancelation (SIC)-enabled wireless
network. First, under each caching design, by utilizing tools from stochastic
geometry and adopting appropriate approximations, we derive a tractable
expression for the successful transmission probability in the general file size
regime. To further obtain design insights, we also derive closed-form
expressions for the successful transmission probability in the small and large
file size regimes, respectively. Then, under each caching design, we consider
the successful transmission probability maximization in the general file size
regime, which is an NP-hard problem. By exploring structural properties, we
successfully transform the original optimization problem into a Multiple-Choice
Knapsack Problem (MCKP), and obtain a near optimal solution with 1/2
approximation guarantee and polynomial complexity. We also obtain closed-form
asymptotically optimal solutions. The analysis and optimization results show
the advantage of the coded caching design over the uncoded caching design, and
reveal the impact of caching and SIC capabilities. Finally, by numerical
results, we show that the two proposed caching designs achieve significant
performance gains over some baseline caching designs.


title:
Classification of the traceless Ricci tensor in 4-dimensional
  pseudo-Riemannian spaces of neutral signature

abstract:
  The traceless Ricci tensor $C_{ab}$ in 4-dimensional pseudo-Riemannian spaces
equipped with the metric of the neutral signature is analyzed. Its algebraic
classification is given. This classification uses the properties of $C_{ab}$
treated as a matrix. The Petrov-Penrose types of Pleba\'nski spinors associated
with the traceless Ricci tensor are given. Finally, the classification is
compared with a similar classification in the complex case.


title: A classification of nullity classes in abelian categories

abstract:
  We give a classification of nullity classes (or torsion classes) in an
abelian category by forming a spectrum of equivalence classes of premonoform
objects. This is parallel to Kanda's classification of Serre subcategories.


title: Recent hadronic resonance measurements at ALICE

abstract:
  In heavy-ion physics, measurements of short-lived hadronic resonances allow
the properties of the hadronic phase of the collision to be studied. In
addition, resonances can be used along with stable hadrons to study parton
energy loss in the quark-gluon plasma and the mechanisms that shape hadron pT
spectra at intermediate transverse momenta. Resonance measurements in small
systems serve as a reference for heavy-ion collisions and contribute to
searches for collective effects. An overview of recent results on hadronic
resonance production measured in ALICE is presented. These results include the
pT spectra and yields of the rho(770)0, K*(892)0, and phi(1020) mesons in pp,
p-Pb, and Pb-Pb collisions at different energies as well as the Sigma(1385)+/-
and Xi(1530)0 baryons in pp and p-Pb collisions.


title: Multi-Quality Multicast Beamforming based on Scalable Video Coding

abstract:
  In this paper, we consider multi-quality multicast beamforming of a video
stream from a multi-antenna base station (BS) to multiple single-antenna users
receiving different qualities of the same video stream, via scalable video
coding (SVC). Leveraging the layered structure of SVC and exploiting
superposition coding (SC) as well as successive interference cancelation (SIC),
we propose a layer-based multi-quality multicast beamforming scheme. To reduce
the complexity, we also propose a quality-based multi-quality multicast
beamforming scheme, which further utilizes the layered structure of SVC and
quality information of all users. Under each scheme, for given quality
requirements of all users, we formulate the corresponding optimal beamforming
design as a non-convex power minimization problem, and obtain a globally
optimal solution for a class of special cases as well as a locally optimal
solution for the general case. Then, we show that the minimum total
transmission power of the quality-based power minimization problem is the same
as that of the layer-based power minimization problem, although the former
incurs a lower computational complexity. Next, we consider the optimal joint
layer selection and quality-based multi quality multicast beamforming design to
maximize the total utility representing the satisfaction with the received
video quality for all users under a given maximum transmission power budget,
which is NP-hard in general. By exploiting the optimal solution of the
quality-based power minimization problem, we develop a greedy algorithm to
obtain a near optimal solution. Finally, numerical results show that the
proposed solutions achieve better performance than existing solutions.


title: Thermal dynamics on the lattice with exponentially improved accuracy

abstract:
  We present a novel simulation prescription for thermal quantum fields on a
lattice that operates directly in imaginary frequency space. By distinguishing
initial conditions from quantum dynamics it provides access to correlation
functions also outside of the conventional Matsubara frequencies $\omega_n=2\pi
n T$. In particular it resolves their frequency dependence between $\omega=0$
and $\omega_1=2\pi T$, where the thermal physics $\omega\sim T$ of
e.g.~transport phenomena is dominantly encoded. Real-time spectral functions
are related to these correlators via an integral transform with rational
kernel, so their unfolding is exponentially improved compared to Euclidean
simulations. We demonstrate this improvement within a $0+1$-dimensional scalar
field theory and show that spectral features inaccessible in standard Euclidean
simulations are quantitatively captured.

categories: hep-lat cond-mat.quant-gas hep-ph nucl-th


title:
Calculated low-energy electron-impact vibrational excitation cross
  sections for CO2 molecule

abstract:
  Vibrational-excitation cross sections of ground electronic state of carbon
dioxide molecule by electron-impact through the CO2-(2\Pi) shape resonance is
considered in the separation of the normal modes approximation. Resonance
curves and widths are computed for each vibrational mode. The calculations
assume decoupling between normal modes and employ the local complex potential
model for the treatment of the nuclear dynamics, usually adopted for the
electron-scattering involving diatomic molecules. Results are presented for
excitation up to 10 vibrational levels in each mode and comparison with data
present in the literature is discussed.


title:
Absolute densities, masses, and radii of the WASP-47 system determined
  dynamically

abstract:
  We present a self-consistent modelling of the available light curve and
radial velocity data of WASP-47 that takes into account the gravitational
interactions between all known bodies in the system. The joint analysis of
light curve and radial velocity data in a multi-planetary system allows
deriving absolute densities, radii, and masses without the use of theoretical
stellar models. For WASP-47 the precision is limited by the reduced dynamical
information that is due to the short time span of the K2 light curve. We
achieve a precision of around 22% for the radii of the star and the transiting
planets, between 40% and 60% for their masses, and between 1.5% and 38% for
their densities. All values agree with previously reported measurements. When
theoretical stellar models are included, the system parameters are determined
with a precision that exceeds that achieved by previous studies, thanks to the
self-consistent modelling of light curve and radial velocity data.


title:
FlyCap: Markerless Motion Capture Using Multiple Autonomous Flying
  Cameras

abstract:
  Aiming at automatic, convenient and non-instrusive motion capture, this paper
presents a new generation markerless motion capture technique, the FlyCap
system, to capture surface motions of moving characters using multiple
autonomous flying cameras (autonomous unmanned aerial vehicles(UAV) each
integrated with an RGBD video camera). During data capture, three cooperative
flying cameras automatically track and follow the moving target who performs
large scale motions in a wide space. We propose a novel non-rigid surface
registration method to track and fuse the depth of the three flying cameras for
surface motion tracking of the moving target, and simultaneously calculate the
pose of each flying camera. We leverage the using of visual-odometry
information provided by the UAV platform, and formulate the surface tracking
problem in a non-linear objective function that can be linearized and
effectively minimized through a Gaussian-Newton method. Quantitative and
qualitative experimental results demonstrate the competent and plausible
surface and motion reconstruction results


title:
Quantum annealing correction at finite temperature: ferromagnetic
  $p$-spin models

abstract:
  The performance of open-system quantum annealing is adversely affected by
thermal excitations out of the ground state. While the presence of energy gaps
between the ground and excited states suppresses such excitations, error
correction techniques are required to ensure full scalability of quantum
annealing. Quantum annealing correction (QAC) is a method that aims to improve
the performance of quantum annealers when control over only the problem (final)
Hamiltonian is possible, along with decoding. Building on our earlier work [S.
Matsuura et al., Phys. Rev. Lett. 116, 220501 (2016)], we study QAC using
analytical tools of statistical physics by considering the effects of
temperature and a transverse field on the penalty qubits in the ferromagnetic
$p$-body infinite-range transverse-field Ising model. We analyze the effect of
QAC on second ($p=2$) and first ($p\geq 3$) order phase transitions, and
construct the phase diagram as a function of temperature and penalty strength.
Our analysis reveals that for sufficiently low temperatures and in the absence
of a transverse field on the penalty qubit, QAC breaks up a single, large free
energy barrier into multiple smaller ones. We find theoretical evidence for an
optimal penalty strength in the case of a transverse field on the penalty
qubit, a feature observed in QAC experiments. Our results provide further
compelling evidence that QAC provides an advantage over unencoded quantum
annealing.


title: Stochastic single-molecule dynamics of synaptic membrane protein domains

abstract:
  Motivated by single-molecule experiments on synaptic membrane protein
domains, we use a stochastic lattice model to study protein reaction and
diffusion processes in crowded membranes. We find that the stochastic
reaction-diffusion dynamics of synaptic proteins provide a simple physical
mechanism for collective fluctuations in synaptic domains, the molecular
turnover observed at synaptic domains, key features of the single-molecule
trajectories observed for synaptic proteins, and spatially inhomogeneous
protein lifetimes at the cell membrane. Our results suggest that central
aspects of the single-molecule and collective dynamics observed for membrane
protein domains can be understood in terms of stochastic reaction-diffusion
processes at the cell membrane.

categories: q-bio.SC physics.bio-ph q-bio.BM q-bio.NC


title: New results on integrable structure of conformal field theory

abstract:
  We explain how to incorporate the action of local integrals of motion into
the fermionic basis for the sine-Gordon model and its UV CFT. The examples up
to the level 4 are presented. Numerical computation support the results.
Possible applications are discussed.


title: Hessian formulas and estimates for parabolic Schr\"odinger operators

abstract:
  We study the Hessian of the fundamental solution to the parabolic problem for
weighted Schr\"odinger operators of the form $\frac 12 \Delta+\nabla h-V$
proving a second order Feynman-Kac formula and obtaining Hessian estimates. For
manifolds with a pole, we use the Jacobian determinant of the exponential map
to offset the volume growth of the Riemannian measure and use the
semi-classical bridge as a delta measure at $y_0$ to obtain exact Gaussian
estimates.
  These estimates are in terms of bounds on $Ric-2 Hess (h)$, on the curvature
operator, and on the cyclic sum of the gradient of the Ricci tensor.


title:
Design, Construction and Performance Tests of a Prototype MicroMegas
  Chamber with Two Readout Planes in a Common Gas Volume

abstract:
  In this paper, the design and the performance of a prototype detector based
on MicroMegas technology with two detection planes in a common gas volume is
discussed. The detector is suited for the forward region of LHC detectors,
addressing the high-rate environment and limited available space. Each
detection plane has an active area of 9x9 cm^2 with a two-dimensional strip
readout and is separated by a common gas region with a height of 14 mm. A
micro-mesh, working as a cathode, is placed in the middle of the common gas
volume separating it into two individual cells. This setup allows for an angle
reconstruction of incoming particles with a precision of 2 mrad. Since this
design reduces the impact of multiple scattering effects by the reduced
material budget, possible applications for low energy beam experiments can be
envisioned. The performance of the prototype detector has been tested with a
4.4 GeV electron beam, provided by the test beam facility at DESY.


title:
Solving Large-scale Systems of Random Quadratic Equations via Stochastic
  Truncated Amplitude Flow

abstract:
  A novel approach termed \emph{stochastic truncated amplitude flow} (STAF) is
developed to reconstruct an unknown $n$-dimensional real-/complex-valued signal
$\bm{x}$ from $m$ `phaseless' quadratic equations of the form
$\psi_i=|\langle\bm{a}_i,\bm{x}\rangle|$. This problem, also known as phase
retrieval from magnitude-only information, is \emph{NP-hard} in general.
Adopting an amplitude-based nonconvex formulation, STAF leads to an iterative
solver comprising two stages: s1) Orthogonality-promoting initialization
through a stochastic variance reduced gradient algorithm; and, s2) A series of
iterative refinements of the initialization using stochastic truncated gradient
iterations. Both stages involve a single equation per iteration, thus rendering
STAF a simple, scalable, and fast approach amenable to large-scale
implementations that is useful when $n$ is large. When $\{\bm{a}_i\}_{i=1}^m$
are independent Gaussian, STAF provably recovers exactly any
$\bm{x}\in\mathbb{R}^n$ exponentially fast based on order of $n$ quadratic
equations. STAF is also robust in the presence of additive noise of bounded
support. Simulated tests involving real Gaussian $\{\bm{a}_i\}$ vectors
demonstrate that STAF empirically reconstructs any $\bm{x}\in\mathbb{R}^n$
exactly from about $2.3n$ magnitude-only measurements, outperforming
state-of-the-art approaches and narrowing the gap from the
information-theoretic number of equations $m=2n-1$. Extensive experiments using
synthetic data and real images corroborate markedly improved performance of
STAF over existing alternatives.


title: Integral matrices as diagonal quadratic forms

abstract:
  In this paper, we investigate the conditions under which a diagonal quadratic
form $\sum_{i=1}^{m}a_i X_i^2$ represents every $n \times n$ integral matrix,
where $a_i$ ($1 \leq i \leq m$) are integers. For $n=2$, we give a necessary
and sufficient condition. Also we give some sufficient conditions for each $n
\geq 2$ where $a_i$ ($1 \leq i \leq m$) are pairwisely coprime.


title: Managing Default Contagion in Inhomogeneous Financial Networks

abstract:
  The aim of this paper is to quantify and manage systemic risk caused by
default contagion in the interbank market. We model the market as a random
directed network, where the vertices represent financial institutions and the
weighted edges monetary exposures between them. Our model captures the strong
degree of heterogeneity observed in empirical data and the parameters can
easily be fitted to real data sets. One of our main results allows us to
determine the impact of local shocks, where initially some banks default, to
the entire system and the wider economy. Here the impact is measured by some
index of total systemic importance of all eventually defaulted institutions. As
a central application, we characterize resilient and non-resilient cases. In
particular, for the prominent case where the network has a degree sequence
without second moment, we show that a small number of initially defaulted banks
can trigger a substantial default cascade. Our results complement and extend
significantly earlier findings derived in the configuration model where the
existence of a second moment of the degree distribution is assumed. As a second
main contribution, paralleling regulatory discussions, we determine minimal
capital requirements for financial institutions sufficient to make the network
resilient to small shocks. An appealing feature of these capital requirements
is that they can be determined locally by each institution without knowing the
complete network structure as they basically only depend on the institution's
exposures to its counterparties.


title: FEAST: An Automated Feature Selection Framework for Compilation Tasks

abstract:
  The success of the application of machine-learning techniques to compilation
tasks can be largely attributed to the recent development and advancement of
program characterization, a process that numerically or structurally quantifies
a target program. While great achievements have been made in identifying key
features to characterize programs, choosing a correct set of features for a
specific compiler task remains an ad hoc procedure. In order to guarantee a
comprehensive coverage of features, compiler engineers usually need to select
excessive number of features. This, unfortunately, would potentially lead to a
selection of multiple similar features, which in turn could create a new
problem of bias that emphasizes certain aspects of a program's characteristics,
hence reducing the accuracy and performance of the target compiler task. In
this paper, we propose FEAture Selection for compilation Tasks (FEAST), an
efficient and automated framework for determining the most relevant and
representative features from a feature pool. Specifically, FEAST utilizes
widely used statistics and machine-learning tools, including LASSO, sequential
forward and backward selection, for automatic feature selection, and can in
general be applied to any numerical feature set. This paper further proposes an
automated approach to compiler parameter assignment for assessing the
performance of FEAST. Intensive experimental results demonstrate that, under
the compiler parameter assignment task, FEAST can achieve comparable results
with about 18% of features that are automatically selected from the entire
feature pool. We also inspect these selected features and discuss their roles
in program execution.


title: Category $\mathcal{J}$ Modules for Hamiltonian Vector Fields on a Torus

abstract:
  Modules for the Lie algebra of Hamiltonian vector fields on a torus, which
admit a compatible action for the commutative algebra of multivariate Laurent
polynomials are called category $\mathcal{J}$. This paper classifies the
indecomposable and the irreducible modules in category $\mathcal{J}$.


title:
Far-field constant-gradient laser accelerator of electrons in an ion
  channel

abstract:
  We predict that electrons in an ion channel can gain ultra-relativistic
energies by simultaneously interacting with a laser pulse and,
counter-intuitively, with a decelerating electric field. The crucial role of
the decelerating field is to maintain high-amplitude betatron oscillations,
thereby enabling constant rate energy flow to the electrons via the direct
laser acceleration mechanism. Multiple harmonics of the betatron motion can be
employed. Injecting electrons into a decelerating phase of a laser wakefield
accelerator is one practical implementation of the scheme.


title:
Bit Allocation for Increased Power Efficiency in 5G Receivers with
  Variable-Resolution ADCs

abstract:
  In future high-capacity wireless systems based on mmWave or massive multiple
input multiple output (MIMO), the power consumption of receiver Analog to
Digital Converters (ADC) is a concern. Although hybrid or analog systems with
fewer ADCs have been proposed, fully digital receivers with many lower
resolution ADCs (and lower power) may be a more versatile solution. In this
paper, focusing on an uplink scenario, we propose to take the optimization of
ADC resolution one step further by enabling variable resolutions in the ADCs
that sample the signal received at each antenna. This allows to give more bits
to the antennas that capture the strongest incoming signal and fewer bits to
the antennas that capture little signal energy and mostly noise. Simulation
results show that, depending on the unquantized link SNR, a power saving in the
order of 20-80% can be obtained by our variable resolution proposal in
comparison with a reference fully digital receiver with a fixed low number of
bits in all its ADCs.


title:
Geodesic orbit metrics in compact homogeneous manifolds with equivalent
  isotropy submodules

abstract:
  A geodesic orbit manifold (GO manifold) is a Riemannian manifold (M,g) with
the property that any geodesic in M is an orbit of a one-parameter subgroup of
a group G of isometries of (M,g). The metric g is then called a G-GO metric in
M. For an arbitrary compact homogeneous manifold M=G/H, we simplify the general
problem of determining the G-GO metrics in M. In particular, if the isotropy
representation of H induces equivalent irreducible submodules in the tangent
space of M, we obtain algebraic conditions, under which, any G-GO metric in M
admits a reduced form. As an application we determine the U(n)-GO metrics in
the complex Stiefel manifolds V_k(C^n).


title:
The Picard-Vessiot theory, constrained cohomology, and linear
  differential algebraic groups

abstract:
  We prove that a differential field K is algebraically closed and
Picard-Vessiot closed if and only if the differential Galois cohomology group
H^1_\partial(K,G) is trivial for any linear differential algebraic group G over
K. We give an application to the parameterized Picard-Vessiot theory.


title:
Currents and Green's functions of impurities out of equilibrium --
  results from inchworm Quantum Monte Carlo

abstract:
  We generalize the recently developed inchworm quantum Monte Carlo method to
the full Keldysh contour with forward, backward, and equilibrium branches to
describe the dynamics of strongly correlated impurity problems with time
dependent parameters. We introduce a method to compute Green's functions,
spectral functions, and currents for inchworm Monte Carlo and show how
systematic error assessments in real time can be obtained. We then illustrate
the capabilities of the algorithm with a study of the behavior of quantum
impurities after an instantaneous voltage quench from a thermal equilibrium
state.


title:
Atom-Based Sensing of Weak Radio Frequency Electric Fields Using
  Homodyne Readout

abstract:
  We utilize a homodyne detection technique to achieve a new sensitivity limit
for atom-based, absolute radio-frequency electric field sensing of $\mathrm{5
\mu V cm^{-1} Hz^{-1/2} }$. A Mach-Zehnder interferometer is used for the
homodyne detection. With the increased sensitivity, we investigate the dominant
dephasing mechanisms that affect the performance of the sensor. In particular,
we present data on power broadening, collisional broadening and transit time
broadening. Our results are compared to density matrix calculations. We show
that photon shot noise in the signal readout is currently a limiting factor. We
suggest that new approaches with superior readout with respect to photon shot
noise are needed to increase the sensitivity further.


title:
Measurement of the mass difference between top quark and antiquark in pp
  collisions at sqrt(s) = 8 TeV

abstract:
  The invariance of the standard model (SM) under the CPT transformation
predicts equality of particle and antiparticle masses. This prediction is
tested by measuring the mass difference between the top quark and antiquark
(Delta m[t] = m[t] - m[t-bar]) that are produced in pp collisions at a
center-of-mass energy of 8 TeV, using events with a muon or an electron and at
least four jets in the final state. The analysis is based on data corresponding
to an integrated luminosity of 19.6 inverse femtobarns collected by the CMS
experiment at the LHC, and yields a value of Delta m[t] = -0.15 +/- 0.19 (stat)
+/- 0.09 (syst) GeV, which is consistent with the SM expectation. This result
is significantly more precise than previously reported measurements.


title:
Entanglement distillation using Schur-Weyl decomposition for three
  qubits

abstract:
  The aim of this work is to examine the exponential rates at which
entanglement distillation occur in three-qubits systems. The approach we will
follow to elucidate the entanglement concentration is based on the Schur-Weyl
decomposition and the Keyl-Werner theorem. In order to clearly state the main
results of this work we will have to introduce the notion of SLOCC equivalence
and the covariant algebra which will allow us to classify states in different
\emph{entanglement classes}. Our main results comprehend the asymptotic rates
for the probability of being in an invariant subspace in the Wedderburn
decomposition of the state with effective Kronecker coefficient
$g_{\alpha\beta\gamma}=1$. We will also present a combinatorial formula for the
effective Kronecker coefficient for two-row Young diagrams. With this work we
hope to shed some light in the way a multipartite system is entangled and at
which rate can we convey entanglement for further applications.


title:
Recovering Finite Parametric Distributions and Functions Using the
  Spherical Mean Transform

abstract:
  The aim of the article is to recover a certain type of finite parametric
distributions and functions using their spherical mean transform which is given
on a certain family of spheres whose centers belong to a finite set $\Gamma$.
For this, we show how the problem of reconstruction can be converted to a
Prony's type system of equations whose regularity is guaranteed by the
assumption that the points in the set $\Gamma$ are in general position. By
solving the corresponding Prony's system we can extract the set of parameters
which define the corresponding function or distribution.


title:
Tailoring magnetic insulator proximity effects in graphene:
  First-principles calculations

abstract:
  We report a systematic first-principles investigation of the influence of
different magnetic insulators on the magnetic proximity effect induced in
graphene. Four different magnetic insulators are considered: two ferromagnetic
europium chalcogenides namely EuO and EuS and two ferrimagnetic insulators
yttrium iron garnet (YIG) and cobalt ferrite (CFO). The obtained
exchange-splitting varies from tens to hundreds of meV. We also find an
electron doping induced by YIG and europium chalcogenides substrates, that
shift the Fermi level up to 0.78 eV and 1.3 eV respectively, whereas hole
doping up to 0.5 eV is generated by CFO. Furthermore, we study the variation of
the extracted exchange and tight binding parameters as a function of the EuO
and EuS thicknesses. We show that those parameters are robust to thickness
variation such that a single monolayer of magnetic insulator can induce a large
magnetic proximity effect on graphene. Those findings pave the way towards
possible engineering of graphene spin-gating by proximity effect especially in
view of recent experiments advancement.


title: TensorLy: Tensor Learning in Python

abstract:
  Tensors are higher-order extensions of matrices. While matrix methods form
the cornerstone of machine learning and data analysis, tensor methods have been
gaining increasing traction. However, software support for tensor operations is
not on the same footing. In order to bridge this gap, we have developed
\emph{TensorLy}, a high-level API for tensor methods and deep tensorized neural
networks in Python. TensorLy aims to follow the same standards adopted by the
main projects of the Python scientific community, and seamlessly integrates
with them. Its BSD license makes it suitable for both academic and commercial
applications. TensorLy's backend system allows users to perform computations
with NumPy, MXNet, PyTorch, TensorFlow and CuPy. They can be scaled on multiple
CPU or GPU machines. In addition, using the deep-learning frameworks as backend
allows users to easily design and train deep tensorized neural networks.
TensorLy is available at https://github.com/tensorly/tensorly


title: Nonreciprocal State Conversion between Microwave and Optical Photons

abstract:
  Optomechanical quantum interfaces can be utilized to connect systems with
distinctively different frequencies in hybrid quantum networks. Here we present
a scheme of nonreciprocal quantum state conversion between microwave and
optical photons via an optomechanical interface. By introducing an auxiliary
cavity and manipulating the phase differences between the linearized
optomechanical couplings, uni-directional state transmission can be achieved.
The interface can function as an isolator, a circulator, and a two-way switch
that routes the input states to a selected output channel. We show that under a
generalized impedance matching condition, the state conversion can reach high
fidelity and is robust against the thermal fluctuations in the mechanical mode.


title:
Dust ion acoustic solitary structures in presence of nonthermally
  distributed electrons and positrons

abstract:
  The purpose of this paper is to extend the recent work of Paul &
Bandyopadhyay [Astrophys. Space Sci. 361, 172(2016)] on the existence of
different dust ion acoustic solitary structures in an unmagnetized
collisionless dusty plasma consisting of negatively charged static dust grains,
adiabatic warm ions, nonthermal electrons and isothermal positrons in a more
generalized form by considering nonthermal positrons instead of isothermal
positrons. The present system supports both positive and negative potential
double layers, coexistence of solitary waves of both polarities and positive
potential supersolitons. The qualitative and the quantitative changes in
existence domains of different solitary structures which occur for the presence
of nonthermal positrons have been presented in comparison with the results of
Paul & Bandyopadhyay [Astrophys. Space Sci. 361, 172(2016)]. The formation of
supersoliton structures and their limitations have been analyzed with the help
of phase portraits of the dynamical system corresponding to the dust ion
acoustic solitary structures. Phase portrait analysis clearly indicates a
smooth transition between soliton and supersoliton.


title:
Reduced-order prediction of rogue waves in two-dimensional deep-water
  waves

abstract:
  We consider the problem of large wave prediction in two-dimensional water
waves. Such waves form due to the synergistic effect of dispersive mixing of
smaller wave groups and the action of localized nonlinear wave interactions
that leads to focusing. Instead of a direct simulation approach, we rely on the
decomposition of the wave field into a discrete set of localized wave groups
with optimal length scales and amplitudes. Due to the short-term character of
the prediction, these wave groups do not interact and therefore their dynamics
can be characterized individually. Using direct numerical simulations of the
governing envelope equations we precompute the expected maximum elevation for
each of those wave groups. The combination of the wave field decomposition
algorithm, which provides information about the statistics of the system, and
the precomputed map for the expected wave group elevation, which encodes
dynamical information, allows (i) for understanding of how the probability of
occurrence of rogue waves changes as the spectrum parameters vary, (ii) the
computation of a critical length scale characterizing wave groups with high
probability of evolving to rogue waves, and (iii) the formulation of a robust
and parsimonious reduced-order prediction scheme for large waves. We assess the
validity of this scheme in several cases of ocean wave spectra.


title: Fair Algorithms for Infinite and Contextual Bandits

abstract:
  We study fairness in linear bandit problems. Starting from the notion of
meritocratic fairness introduced in Joseph et al. [2016], we carry out a more
refined analysis of a more general problem, achieving better performance
guarantees with fewer modelling assumptions on the number and structure of
available choices as well as the number selected. We also analyze the
previously-unstudied question of fairness in infinite linear bandit problems,
obtaining instance-dependent regret upper bounds as well as lower bounds
demonstrating that this instance-dependence is necessary. The result is a
framework for meritocratic fairness in an online linear setting that is
substantially more powerful, general, and realistic than the current state of
the art.


title:
Strong correlations and the search for high-Tc superconductivity in
  chromium pnictides and chalcogenides

abstract:
  Undoped iron superconductors accommodate $n=6$ electrons in five d-orbitals.
Experimental and theoretical evidence shows that the strength of correlations
increases with hole-doping, as the electronic filling approaches half-filling
with $n=5$ electrons. This evidence delineates a scenario in which the parent
compound of iron superconductors is the half-filled system, in analogy to
cuprate superconductors. In cuprates the superconductivity can be induced upon
electron or hole doping. In this work we propose to search for high-Tc
superconductivity and strong correlations in chromium pnictides and
chalcogenides with $n<5$ electrons. By means of ab-initio, slave spin and
multi-orbital RPA calculations we analyse the strength of the correlations and
the superconducting and magnetic instabilities in these systems with main focus
on LaCrAsO. We find that electron-doped LaCrAsO is a strongly correlated system
with competing magnetic interactions, being $(\pi,\pi)$ antiferromagnetism and
nodal d-wave pairing the most plausible magnetic and superconducting
instabilities, respectively.


title: Near-periodical spin period evolution in the binary system LMC X-4

abstract:
  In this paper we investigated the long-term evolution of the pulse-period in
the high-mass X-ray binary LMC X-4 by taking advantage of more than 43~yrs of
measurements in the X-ray domain. Our analysis revealed for the first time that
the source is displaying near-periodical variations of its spin period on a
time scale of roughly 6.8~yrs, making LMC X-4 one of the known binary systems
showing remarkable long term spin torque reversals. We discuss different
scenarios to interpret the origin of these torque reversals.


title: Topological Boundary States in 1D: An Effective Fabry-Perot Model

abstract:
  We present a general and useful method to predict the existence, frequency,
and spatial properties of gap states in photonic (and other) structures with a
gapped spectrum. This method is established using the scattering approach. It
offers a viewpoint based on a geometrical Fabry-Perot model. We demonstrate the
capabilities of this model by predicting the behaviour of topological edge
states in quasi-periodic structures. A proposition to use this model in Casimir
physics is presented.


title: Exact analytical solutions for ADAFs

abstract:
  We obtain two-dimensional exact analytic solutions for the structure of the
hot accretion flows without wind. We assume that the only non-zero component of
the stress tensor is $T_{r\varphi}$. Furthermore we assume that the value of
viscosity coefficient $\alpha$ varies with $\theta$. We find radially
self-similar solutions and compare them with the numerical and the analytical
solutions already studied in the literature. The no-wind solution obtained in
this paper may be applied to the nuclei of some cool-core clusters.


title: Complex geodesics and variational calculus for univalent functions

abstract:
  It turns out that complex geodesics in Teichm\"uller spaces with respect to
their invariant metrics are intrinsically connected with variational calculus
for univalent functions.
  We describe this connection and show how geometric features associated to
these metrics and geodesics provide deep distortion results for various classes
of functions with quasiconformal extensions and create new phenomena which do
not appear in the classical geometric function theory.


title: Sequence-to-sequence neural network models for transliteration

abstract:
  Transliteration is a key component of machine translation systems and
software internationalization. This paper demonstrates that neural
sequence-to-sequence models obtain state of the art or close to state of the
art results on existing datasets. In an effort to make machine transliteration
accessible, we open source a new Arabic to English transliteration dataset and
our trained models.


title:
Inchworm Monte Carlo for exact non-adiabatic dynamics I. Theory and
  algorithms

abstract:
  In this paper we provide a detailed description of the inchworm Monte Carlo
formalism for the exact study of real-time non-adiabatic dynamics. This method
optimally recycles Monte Carlo information from earlier times to greatly
suppress the dynamical sign problem. Using the example of the spin-boson model,
we formulate the inchworm expansion in two distinct ways: The first with
respect to an expansion in the system-bath coupling and the second as an
expansion in the diabatic coupling. The latter approach motivates the
development of a cumulant version of the inchworm Monte Carlo method, which has
the benefit of improved scaling. This paper deals completely with methodology,
while Paper II provides a comprehensive comparison of the performance of the
inchworm Monte Carlo algorithms to other exact methodologies as well as a
discussion of the relative advantages and disadvantages of each.


title:
Thermoelectric Studies of Nanoporous Thin Films with Adjusted Pore-Edge
  Charges

abstract:
  In recent years, nanoporous thin films have been widely studied for
thermoelectric applications. High thermoelectric performance is reported for
nanoporous Si films, which is attributed to the dramatically reduced lattice
thermal conductivity and bulk-like electrical properties. Porous materials can
also be used in gas sensing applications by engineering the surface-trapped
charges on pore edges. In this work, an analytical model is developed to
explore the relationship between the thermoelectric properties and pore-edge
charges in a periodic two-dimensional nanoporous material. The presented model
can be widely used to analyze the measured electrical properties of general
nanoporous thin films and two-dimensional materials.


title:
Direct photon-hadron correlation measurement and a way towards
  photon-triggered jets at RHIC

abstract:
  We report the results of $\gamma_{\rm dir}$ and $\pi^{0}$-hadron azimuthal
correlations as a measure of the away-side jet-like correlated yields in
central Au+Au and p+p collisions at $\sqrt{s_{_{NN}}}$=200 GeV in the STAR
experiment. The charged-hadron per-trigger yields at mid-rapidity with respect
to high-$p_{T}$ $\gamma_{\rm dir}$ and $\pi^{0}$ in central Au+Au collisions
are compared with p+p collisions. Within uncertainties, the same $z_{T}$
(~$p_{T}^{\mathrm{assoc}}$ / $p_{T}^{\mathrm{trig}}$) dependence of the
suppression is observed for $\gamma_{\rm dir}$ and $\pi^{0}$ - triggers. The
results are compared with energy-loss model predictions. The $\gamma-\rm jet$
measurements can provide further understanding on the redistribution of
in-medium energy loss. Ongoing $\gamma-\rm jet$ studies in the STAR experiment
are also discussed.


title: A multi-class extension of the mean field Bolker-Pacala population model

abstract:
  We extend our earlier mean field approximation of the Bolker-Pacala model of
population dynamics by dividing the population into N classes, using a mean
field approximation for each class but also allowing migration between classes
as well as possibly suppressive influence of the population of one class over
another class. For N at least 2, we obtain one symmetric non-trivial
equilibrium for the system and give global limit theorems. For N=2, we
calculate all equilibrium solutions, which, under additional conditions,
include multiple non-trivial equilibria. Lastly, we prove geometric ergodicity
regardless of the number of classes when there is no population suppression
across the classes.


title: Complete linear optical isolation at the microscale with ultralow loss

abstract:
  Low-loss optical isolators and circulators are critical nonreciprocal
components for signal routing and protection, but their chip-scale integration
is not yet practical using standard photonics foundry processes. The
significant challenges that confront integration of magneto-optic nonreciprocal
systems on chip have made imperative the exploration of magnet free
alternatives. However, none of these approaches have yet demonstrated linear
optical isolation with ideal characteristics over a microscale footprint -
simultaneously incorporating large contrast with ultralow forward loss - having
fundamental compatibility with photonic integration in standard waveguide
materials. Here we demonstrate that complete linear optical isolation can be
obtained within any dielectric waveguide using only a whispering-gallery
microresonator pumped by a single-frequency laser. The isolation originates
from a nonreciprocal induced transparency based on a coherent light-sound
interaction, with the coupling originating from the traveling-wave Brillouin
scattering interaction, that breaks time-reversal symmetry within the
waveguide-resonator system. Our result demonstrates that material-agnostic and
wavelength-agnostic optical isolation is far more accessible for chip-scale
photonics than previously thought.


title: The geodesic X-ray transform with a $GL(n,\mathbb{C})$-connection

abstract:
  We derive reconstruction formulas for a family of geodesic ray transforms
with connection, defined on simple Riemannian surfaces. Such formulas provide
injectivity of such all transforms in a neighbourhood of constant curvature
metrics and non-unitary connections with curvature close to zero. If certain
Fredholm equations are injective in the absence of connection, then for any
smooth enough connection multiplied by a complex parameter, the corresponding
transform is injective for all values of that parameter outside a discrete set.
Range characterizations are also provided, as well as numerical illustrations.


title: Density Tracking by Quadrature for Stochastic Differential Equations

abstract:
  We develop and analyze a method, density tracking by quadrature (DTQ), to
compute the probability density function of the solution of a stochastic
differential equation. The derivation of the method begins with the
discretization in time of the stochastic differential equation, resulting in a
discrete-time Markov chain with continuous state space. At each time step, DTQ
applies quadrature to solve the Chapman-Kolmogorov equation for this Markov
chain. In this paper, we focus on a particular case of the DTQ method that
arises from applying the Euler-Maruyama method in time and the trapezoidal
quadrature rule in space. Our main result establishes that the density computed
by DTQ converges in $L^1$ to both the exact density of the Markov chain (with
exponential convergence rate), and to the exact density of the stochastic
differential equation (with first-order convergence rate). We establish a
Chernoff bound that implies convergence of a domain-truncated version of DTQ.
We carry out numerical tests to show that the empirical performance of DTQ
matches theoretical results, and also to demonstrate that DTQ can compute
densities several times faster than a Fokker-Planck solver, for the same level
of error.


title: Investigation of 11B+197Au Reaction at Intermediate Energies

abstract:
  Mechanism of nuclear reactions on 197Au induced by 11B ions at energies above
Coulomb barrier was studied by induced-activity method and gamma-spectroscopy.
The cross sections of the reaction fragments from 197Au induced by 11B ions
were measured at bombarding energies 137.5 and 255.5 MeV. The fission process
was investigated by using multimodal fission approach at the energy 137.5 MeV,
and pure symmetric distribution at 255.5 MeV. It was observed that the
transferred linear momentum provides the information on the initial
projectile-target information. The fissility for both fission reactions under
study was deduced from measured fission cross section using the total inelastic
cross section. Comparison with proton-induced fission shown, that the linear
momentum transferred to the fissile system depends on the probe.


title: Gap theorems for robust satisfiability: Boolean CSPs and beyond

abstract:
  A computational problem exhibits a "gap property" when there is no tractable
boundary between two disjoint sets of instances. We establish a Gap Trichotomy
Theorem for a family of constraint problem variants, completely classifying the
complexity of possible ${\bf NP}$-hard gaps in the case of Boolean domains. As
a consequence, we obtain a number of dichotomies for the complexity of specific
variants of the constraint satisfaction problem: all are either polynomial-time
tractable or $\mathbf{NP}$-complete. Schaefer's original dichotomy for
$\textsf{SAT}$ variants is a notable particular case.
  Universal algebraic methods have been central to recent efforts in
classifying the complexity of constraint satisfaction problems. A second
contribution of the article is to develop aspects of the algebraic approach in
the context of a number of variants of the constraint satisfaction problem. In
particular, this allows us to lift our results on Boolean domains to many
templates on non-Boolean domains.


title:
Direct observation of electron emission as a result of a VVV Auger
  transition in the valence band of Graphene

abstract:
  We report the first direct observation of electron emission into the vacuum
as a result of a VVV Auger transition resulting from the relaxation of a deep
hole in the valence band. A beam of low energy (<1.25eV) positrons was used to
deposit positrons onto the surface of samples consisting of single layer
graphene, multi-layer graphene and graphite. The distribution of electrons
emitted from the samples as a result of the annihilation of the positron showed
peak extending up to ~12 eV with a maximum at ~4eV. The observed peak was ~17
times larger than the previously observed annihilation induced C KVV peak. An
analysis based upon a density functional theory calculation of the positron
annihilation rates indicates that the width and intensity of the peak is
consistent with electron emission resulting from VVV Auger transition excited
by the annihilation of valence band electrons. Good agreement was found between
the data from the single layer graphene on Cu surface with a theoretical line
shape found from a self-folding of the density of states for a free standing
graphene layer. The agreement between the theoretical and measured intensities
for the KVV and VVV transitions indicates that the branching ratio for holes to
decay via an Auger transition is nearly the same in both cases (i.e. close to
100%). Our results suggest the possibility of using annihilation induced VVV
Auger spectroscopy to study the properties of the local density of states and
the hole decay processes in materials in which the valence band width exceeds
the work function.


title: Amenability of trees

abstract:
  We will give a criterion for the amenability of arbitrary locally finite
trees. The criterion is based on the trimming operator which is defined on the
space of trees. As an application, we obtain a necessary and sufficient
condition for that amenability of Galton-Watson trees.


title: On local geometry of vector distributions with given Jacobi symbols

abstract:
  Based on the ideas of Optimal Control, we introduce the new basic
characteristic of a bracket generating distribution, the Jacobi symbol. In
contrast to the classical Tanaka symbol, the set of Jacobi symbols is discrete
and classifiable. We give an explicit and unified algebraic procedure for the
construction of the canonical frames (the structure of absolute parallelism)
for all distribution with given Jacobi symbol. We describe all Jacobi symbols
for which this procedure ends up in a finite number of steps (i.e. all Jacobi
symbols of finite type) and distinguish the symplectically flat distributions
with given Jacobi symbol, which in the case of finite type are the maximally
symmetric distribution among all distribution with given Jacobi symbol. Also,
for the most of Jacobi symbols we relate the prolongation procedure and the
resulting prolongation algebra, which is the algebra of infinitesimal
symmetries of the corresponding symplectically flat distribution, to the
standard (in the sense of Kobayashi and Sternberg) prolongation of certain
subspace in the algebra of infinitesimal symmetries of the flat
(unparametrized) curve of flags associated with the Jacobi symbol. Finally, we
give an upper bounds for the size of the resulting prolongation algebra in
terms of certain spaces of polynomials vanishing on certain projective
varieties. For some class of Jacobi symbols we are able to identify the
resulting prolongation algebra with such spaces of polynomials. In this way we
get the description of the prolongation algebra for all Jacobi symbols of
finite type appearing in rank 2 and rank 3 distributions and also for most of
such Jacobi symbols appearing in rank 4 distributions. In particular, in the
case of rank 3 distributions this description is given in terms of the
tangential developable and the secant varieties of a rational normal curve.


title:
Maximum Rate of Growth of Enstrophy in Solutions of the Fractional
  Burgers Equation

abstract:
  This investigation is a part of a research program aiming to characterize the
extreme behavior possible in hydrodynamic models by analyzing the maximum
growth of certain fundamental quantities. We consider here the rate of growth
of the classical and fractional enstrophy in the fractional Burgers equation in
the subcritical and supercritical regimes. Since solutions to this equation
exhibit, respectively, globally well-posed behavior and finite-time blow-up in
these two regimes, this makes it a useful model to study the maximum
instantaneous growth of enstrophy possible in these two distinct situations.
First, we obtain estimates on the rates of growth and then show that these
estimates are sharp up to numerical prefactors. This is done by numerically
solving suitably defined constrained maximization problems and then
demonstrating that for different values of the fractional dissipation exponent
the obtained maximizers saturate the upper bounds in the estimates as the
enstrophy increases. We conclude that the power-law dependence of the enstrophy
rate of growth on the fractional dissipation exponent has the same global form
in the subcritical, critical and parts of the supercritical regime. This
indicates that the maximum enstrophy rate of growth changes smoothly as global
well-posedness is lost when the fractional dissipation exponent attains
supercritical values. In addition, nontrivial behavior is revealed for the
maximum rate of growth of the fractional enstrophy obtained for small values of
the fractional dissipation exponents. We also characterize the structure of the
maximizers in different cases.


title: Billiards in near rectangles

abstract:
  For every quadrilateral sufficiently close to a rectangle, we shall show that
it possess a periodic billiard path. This is an REU work done at ICERM in
Summer 2012.


title:
Data-driven Estimation of Origin-Destination Demand and User Cost
  Functions for the Optimization of Transportation Networks

abstract:
  In earlier work (Zhang et al., 2016) we used actual traffic data from the
Eastern Massachusetts transportation network in the form of spatial average
speeds and road segment flow capacities in order to estimate Origin-Destination
(OD) flow demand matrices for the network. Based on a Traffic Assignment
Problem (TAP) formulation (termed "forward problem"), in this paper we use a
scheme similar to our earlier work to estimate initial OD demand matrices and
then propose a new inverse problem formulation in order to estimate user cost
functions. This new formulation allows us to efficiently overcome numerical
difficulties that limited our prior work to relatively small subnetworks and,
assuming the travel latency cost functions are available, to adjust the values
of the OD demands accordingly so that the flow observations are as close as
possible to the solutions of the forward problem. We also derive sensitivity
analysis results for the total user latency cost with respect to important
parameters such as road capacities and minimum travel times. Finally, using the
same actual traffic data from the Eastern Massachusetts transportation network,
we quantify the Price of Anarchy (POA) for a much larger network than that in
Zhang et al. (2016).


title: Robin boundary conditions are generic in quantum mechanics

abstract:
  Robin (or mixed) boundary conditions in quantum mechanics have received
considerable attention in the last two decades, in particular, for applications
to nanoscale systems. However, their utility has remained obscure to the larger
physics community; in fact, one may find extant claims in the literature about
the supposed naturalness of the specific Dirichlet (or vanishing) boundary
condition. Here we demonstrate that not only are Dirichlet boundary conditions
unnatural, but that Robin boundary conditions have utility in the
long-wavelength approximation of short-ranged potentials. For illustration, we
consider a non-relativistic particle in one dimension under the influence of
the multi-step and Morse potential. We derive the scattering and bound states
for these potentials and determine the parameters that describe those states in
an effective system, namely one in which there is a free particle with a
boundary. This method appears to be generically applicable and also
generalizable to many other real systems.


title: Diversity Promoting Online Sampling for Streaming Video Summarization

abstract:
  Many applications benefit from sampling algorithms where a small number of
well chosen samples are used to generalize different properties of a large
dataset. In this paper, we use diverse sampling for streaming video
summarization. Several emerging applications support streaming video, but
existing summarization algorithms need access to the entire video which
requires a lot of memory and computational power. We propose a memory efficient
and computationally fast, online algorithm that uses competitive learning for
diverse sampling. Our algorithm is a generalization of online K-means such that
the cost function reduces clustering error, while also ensuring a diverse set
of samples. The diversity is measured as the volume of a convex hull around the
samples. Finally, the performance of the proposed algorithm is measured against
human users for 50 videos in the VSUMM dataset. The algorithm performs better
than batch mode summarization, while requiring significantly lower memory and
computational requirements.


title: Symmetry of bilinear master equations for a quantum oscillator

abstract:
  We study the most general continuous transformation on the generators of
bilinear master equations of a quantum oscillator. We find that transformation
operators that preserve the hermiticity of density operators and conserve the
probability of reduced dynamics should be adjoint-symmetric, and they are not
limited to the pure product of unitary operators in the bra and ket space but
could be a mixture of them. We need to include the more general transformation
operators to explore the full symmetry of generic reduced dynamics. We discuss
how the operators are related to those considered in previous works, and
illustrate how they leave the reduced dynamics form invariant, or map one into
the other. The positive semidefinite requirement on the density operator can be
imposed to give a valid range of transformation parameters.


title: Positivity in convergence of the inverse $\sigma_{n-1}$-flow

abstract:
  We study positivity in the conjecture proposed by Lejmi and Sz\'{e}kelyhidi
on finding effective necessary and sufficient conditions for solvability of the
inverse $\sigma_k$ equation, or equivalently, for convergence of the inverse
$\sigma_k$-flow. In particular, for the inverse $\sigma_{n-1}$-flow we
partially verify their conjecture by obtaining the desired positivity for
$(n-1, n-1)$ cohomology classes. As an application, we also partially verify
their conjecture for 3-folds.


title: Conditional Image Synthesis With Auxiliary Classifier GANs

abstract:
  Synthesizing high resolution photorealistic images has been a long-standing
challenge in machine learning. In this paper we introduce new methods for the
improved training of generative adversarial networks (GANs) for image
synthesis. We construct a variant of GANs employing label conditioning that
results in 128x128 resolution image samples exhibiting global coherence. We
expand on previous work for image quality assessment to provide two new
analyses for assessing the discriminability and diversity of samples from
class-conditional image synthesis models. These analyses demonstrate that high
resolution samples provide class information not present in low resolution
samples. Across 1000 ImageNet classes, 128x128 samples are more than twice as
discriminable as artificially resized 32x32 samples. In addition, 84.7% of the
classes have samples exhibiting diversity comparable to real ImageNet data.


title: Wave equations with moving potentials

abstract:
  In this paper, we study the endpoint reversed Strichartz estimates along
general time-like trajectories for wave equations in $\mathbb{R}^{3}$. We also
discuss some applications of the reversed Strichartz estimates and the
structure of wave operators to the wave equation with one potential. These
techniques are useful to analyze the stability problem of traveling solitons.


title:
A Counting Lemma for Binary Matroids and Applications to Extremal
  Problems

abstract:
  In graph theory, the Szemer\'edi regularity lemma gives a decomposition of
the indicator function for any graph $G$ into a structured component, a uniform
part, and a small error. This result, in conjunction with a counting lemma that
guarantees many copies of a subgraph $H$ provided a copy of $H$ appears in the
structured component, is used in many applications to extremal problems. An
analogous decomposition theorem exists for functions over $\mathbb{F}_p^n$.
Specializing to $p=2$, we obtain a statement about the indicator functions of
simple binary matroids. In this paper we extend previous results to prove a
corresponding counting lemma for binary matroids. We then apply this counting
lemma to give simple proofs of some known extremal results, analogous to the
proofs of their graph-theoretic counterparts, and discuss how to use similar
methods to attack a problem concerning the critical numbers of dense binary
matroids avoiding a fixed submatroid.


title:
Ergodic Properties of Heisenberg Continued Fractions with Applications
  in Hyperbolic Geometry

abstract:
  We give an overview of how to construct continued fractions on the Heisenberg
group $\mathbb{H}$, the projective and planar Siegel models of the group, and
how to perform computations on the group using matrices. We discuss and work
with some recent results of Vandehey on the classification of which elements of
the Heisenberg group have eventually periodic continued fraction
expansions.Then we examine and work with major theorems in ergodic theory to
explore results concerning growth of denominators and digit frequency, relating
the results to hyperbolic geometry.


title: The moduli space of curves and its invariants

abstract:
  This note is about invariants of moduli spaces of curves. It includes their
intersection theory and cohomology. Our main focus in on the distinguished
piece containing the so called tautological classes. These are the most natural
classes on the moduli space. We give a review of known results and discuss
their conjectural descriptions.


title:
A Scalable and Robust Framework for Intelligent Real-time Video
  Surveillance

abstract:
  In this paper, we present an intelligent, reliable and storage-efficient
video surveillance system using Apache Storm and OpenCV. As a Storm topology,
we have added multiple information extraction modules that only write important
content to the disk. Our topology is extensible, capable of adding novel
algorithms as per the use case without affecting the existing ones, since all
the processing is independent of each other. This framework is also highly
scalable and fault tolerant, which makes it a best option for organisations
that need to monitor a large network of surveillance cameras.


title: Grackle: a Chemistry and Cooling Library for Astrophysics

abstract:
  We present the Grackle chemistry and cooling library for astrophysical
simulations and models. Grackle provides a treatment of non-equilibrium
primordial chemistry and cooling for H, D, and He species, including H2
formation on dust grains; tabulated primordial and metal cooling; multiple UV
background models; and support for radiation transfer and arbitrary heat
sources. The library has an easily implementable interface for simulation codes
written in C, C++, and Fortran as well as a Python interface with added
convenience functions for semi-analytical models. As an open-source project,
Grackle provides a community resource for accessing and disseminating
astrochemical data and numerical methods. We present the full details of the
core functionality, the simulation and Python interfaces, testing
infrastructure, performance, and range of applicability. Grackle is a fully
open-source project and new contributions are welcome.


title: $f_2(1810)$ as a triangle singularity

abstract:
  We perform calculations showing that a source producing $K^* \bar{K}^*$ in $J
= 2$ and $L=0$ gives rise to a triangle singularity at $1810$ MeV with a width
of about $200$ MeV from the mechanism $K^* \to \pi K$ and then $K\bar{K}^*$
merging into the $a_1(1260)$ resonance. We suggest that this is the origin of
the present $f_2(1810)$ resonance and propose to look at the $\pi a_1(1260)$
mode in several reactions to clarify the issue.


title:
Enhanced optical nonlinearities in air-cladding silicon pedestal
  waveguides

abstract:
  The third-order optical nonlinearity in optical waveguides has found
applications in optical switching, optical wavelength conversion, optical
frequency comb generation, and ultrafast optical signal processing. The
development of an integrated waveguide platform with a high nonlinearity is
therefore important for nonlinear integrated photonics. Here, we report the
observation of an enhancement in the nonlinearity of an air-cladding silicon
pedestal waveguide. We observe enhanced nonlinear spectral broadening compared
to a conventional silicon-on-insulator waveguide. At the center wavelength of
1555 nm, the nonlinear-index coefficient of air-cladding silicon pedestal
waveguide is measured to be about 5% larger than that of a conventional
silicon-on-insulator waveguide. We observe enhanced spectral broadening from
self-phase modulation of an optical pulse in the pedestal waveguide. The
interaction of light with the confined acoustic phonons in the pedestal
structure gives rise to a larger nonlinear-index coefficient. The experimental
results agree well with the theoretical models.


title:
Insulator-metal transition in deep Sr-vacant spin-orbit Mott insulator
  Sr2IrO4

abstract:
  Sr2IrO4 exhibits a novel insulating state assisted by spin-orbit
interactions. A series of polycrystalline samples of Sr2-xIrO4 have been
synthesized. It is found that deep Sr-vacancies of Sr2-xIrO4 greatly reduce the
rotation of IrO6 octahedral, and more importantly, a significant structural
change occurs around x = 0.48 in both the lattice constants and the Ir-O2 bond
length. An insulator-metal transition (IMT) appears and a non-Fermi-liquid
metallic electronic state has been proved at x>0.48 in Sr2-xIrO4. Furthermore,
a sudden drop emerges of the localization temperature T0 and the
antiferromagnetic (AFM) transition temperature TN in Sr1.5IrO4, together with
the Curie-Weiss temperature reversing its sign. These abrupt changes are
closely related with the reduction of the rotation crystal structure.


title: Steady hydrodynamic model of semiconductors with sonic boundary

abstract:
  In this paper, we study the well-posedness/ill-posedness and regularity of
stationary solutions to the hydrodynamic model of semiconductors represented by
Euler-Poisson equations with sonic boundary. When the doping profile is
subsonic, we prove that, the steady-state equations with sonic boundary possess
a unique interior subsonic solution, and at least one interior supersonic
solution, and if the relaxation time is large and the doping profile is a small
perturbation of constant, then the equations admit infinitely many transonic
shock solutions, while, if the relaxation time is small enough and the doping
profile is a subsonic constant, then the equations admits infinitely many $C^1$
smooth transonic solutions, and no transonic shock solution exists. When the
doping profile is supersonic, we show that the system does not hold any
subsonic solution, furthermore, the system doesn't admit any supersonic
solution or any transonic solution if such a supersonic doping profile is small
or the relaxation time is small, but it has at least one supersonic solution
and infinitely many transonic solutions if the supersonic doping profile is
close to the sonic line and the relaxation time is large. The interior
subsonic/supersonic solutions all are global $C^{\frac{1}{2}}$
H\"older-continuous, and the exponent $\frac{1}{2}$ is optimal. The
non-existence of any type solutions in the case of small doping profile or
small relaxation time indicates that the semiconductor effect for the system is
remarkable and cannot be ignored. The proof for the existence of
subsonic/supersonic solutions is the technical compactness analysis combining
the energy method and the phase-plane analysis, while the approach for the
existence of multiple transonic solutions is artfully constructed. The results
obtained significantly improve and develop the existing studies.


title:
A New Necessary Condition for the Hyponormality of Toeplitz Operators on
  the Bergman Space

abstract:
  A well known result of C. Cowen states that, for a symbol $\varphi \in
L^{\infty }, \; \varphi \equiv \bar{f}+g \;\;(f,g\in H^{2})$, the Toeplitz
operator $T_{\varphi }$ acting on the Hardy space of the unit circle is
hyponormal if and only if $f=c+T_{\bar{h}}g,$ for some $c\in {\mathbb C}$,
$h\in H^{\infty }$, $\left\| h\right\| _{\infty}\leq 1.$ \ In this note we
consider possible versions of this result in the {\it Bergman} space case. \
Concretely, we consider Toeplitz operators on the Bergman space of the unit
disk, with symbols of the form $$\varphi \equiv \alpha z^n+\beta z^m +\gamma
\overline z ^p + \delta \overline z ^q,$$ where $\alpha, \beta, \gamma, \delta
\in \mathbb{C}$ and $m,n,p,q \in \mathbb{Z}_+$, $m < n$ and $p < q$. \ By
letting $T_{\varphi}$ act on vectors of the form $$z^k+c z^{\ell}+d z^r \; \;
(k<\ell<r),$$ we study the asymptotic behavior of a suitable matrix of inner
products, as $k \rightarrow \infty$. \ As a result, we obtain a sharp
inequality involving the above mentioned data: $$ \left|\alpha \right|^2 n^2 +
\left|\beta \right|^2 m^2 - \left|\gamma \right|^2 p^2 - \left|\delta \right|^2
q^2 \ge 2 \left|\bar \alpha \beta m n - \bar \gamma \delta p q \right|. $$ This
inequality improves a number of existing results, and it is intended to be a
precursor of basic necessary conditions for joint hyponormality of tuples of
Toeplitz operators acting on Bergman spaces in one or several complex
variables.


title: Field-created diverse quantizations in phosphorenes

abstract:
  Electronic properties of few-layer phosphorenes are investigated by the
generalized tight-binding model. They are greatly diversified by the electric
and magnetic fields ($E_z$ and $B_z$). The $E_z$-induced gap transition, Dirac
cones, oscillatory bands and critical points are present in bilayer system, but
absent in monolayer one. The diverse magnetic quantization phenomena cover the
coexistent two subgroups of Landau levels, the uniform and non-uniform energy
spacings, and the crossing and anti-crossing behaviors. Specifically, the
wavefunctions exhibit the dramatic changes between the well-behaved and
multi-mode oscillations. The feature-rich energy spectra are reveled in density
of states as .many special structures which could be verified from scanning
tunneling spectroscopy.


title:
Crystal structure and physical properties of the Sr-vacant
  spin-orbit-coupling induced Mott insulator Sr2-xIrO4

abstract:
  A series of polycrystalline samples of Sr2-xIrO4 have been synthesized by a
solid-state reaction method. The crystal structure of this doped system can be
explained on the basis of the extended nature of 5d electrons and strontium
vacancies in Sr2-xIrO4. The analysis of the temperature-dependent resistance of
these samples reveals the semiconducting feature, where three dimensional
variable range hopping behavior is observed at temperatures lower than 120K,
Arrhenius type in intermediate temperatures from 140K to 200K, and
two-dimensional (2D) weak localization at high temperatures from 220K to 300K.
Correspondingly, temperature-dependent magnetic properties in the range of x
less than 0.30 can be described by the antiferromagnetically ordered spin
system.


title: Generalized fluid theory including non-Maxwellian kinetic effects

abstract:
  The results obtained by the plasma physics community for the validation and
the prediction of turbulence and transport in magnetized plasma come mainly
from the use of very CPU-consuming particle-in-cell or (gyro)kinetic codes
which naturally include non-Maxwellian kinetic effects. To date, fluid codes
are not considered to be relevant for the description of these kinetic effects.
Here, after revisiting the limitations of the current fluid theory developed in
the 19th century, we generalize the fluid theory including kinetic effects such
as non-Maxwellian super-thermal tails with as few fluid equations as possible.
The collisionless and collisional fluid closures from the nonlinear Landau
Fokker-Planck collision operator are shown for an arbitrary collisionality.
Indeed, the first fluid models associated with two examples of collisionless
fluid closures are obtained by assuming an analytic non-Maxwellian distribution
function (e.g., the INMDF [O. Izacard, Phys. Plasmas 23, 082504 (2016)]). One
of the main differences with the literature is our analytic representation of
the distribution function in the velocity phase space with as few hidden
variables as possible thanks to the use of non-orthogonal basis sets. These new
non-Maxwellian fluid equations could initiate the next generation of fluid
codes including kinetic effects and can be expanded to other scientific
disciplines such as astrophysics, condensed matter, or hydrodynamics. As a
validation test, we perform a numerical simulation based on a minimal reduced
INMDF fluid model. The result of this test is the discovery of the origin of
particle and heat diffusion. The diffusion is due to the competition between a
growing INMDF on short time scales due to spatial gradients and the
thermalization on longer time scales. The results shown here could draw the
breaking of some unsolved understandings of the turbulence.

categories: physics.plasm-ph physics.ao-ph physics.comp-ph physics.flu-dyn physics.space-ph


title: Super-resolution estimation of cyclic arrival rates

abstract:
  Exploiting the fact that most arrival processes exhibit cyclic behaviour, we
propose a simple procedure for estimating the intensity of a nonhomogeneous
Poisson process. The estimator is the super-resolution analogue to Shao 2010
and Shao & Lii 2011, which is a sum of $p$ sinusoids where $p$ and the
frequency, amplitude, and phase of each wave are not known and need to be
estimated. This results in an interpretable yet flexible specification that is
suitable for use in modelling as well as in high resolution simulations.
  Our estimation procedure sits in between classic periodogram methods and
atomic/total variation norm thresholding. Through a novel use of window
functions in the point process domain, our approach attains super-resolution
without semidefinite programming. Under suitable conditions, finite sample
guarantees can be derived for our procedure. These resolve some open questions
and expand existing results in spectral estimation literature.


title: Equilibration in the Kac Model using the GTW Metric $d_2$

abstract:
  We use the Fourier based Gabetta-Toscani-Wennberg (GTW) metric $d_2$ to study
the rate of convergence to equilibrium for the Kac model in $1$ dimension. We
take the initial velocity distribution of the particles to be a Borel
probability measure $\mu$ on $\mathbb{R}^n$ that is symmetric in all its
variables, has mean $\vec{0}$ and finite second moment. Let $\mu_t(dv)$ denote
the Kac-evolved distribution at time $t$, and let $R_\mu$ be the angular
average of $\mu$. We give an upper bound to $d_2(\mu_t, R_\mu)$ of the form
$\min\{ B e^{-\frac{4 \lambda_1}{n+3}t}, d_2(\mu,R_\mu)\}$, where $\lambda_1 =
\frac{n+2}{2(n-1)}$ is the gap of the Kac model in $L^2$ and $B$ depends only
on the second moment of $\mu$. We also construct a family of Schwartz
probability densities $\{f_0^{(n)}: \mathbb{R}^n\rightarrow \mathbb{R}\}$ with
finite second moments that shows practically no decrease in $d_2(f_0(t),
R_{f_0})$ for time at least $\frac{1}{2\lambda}$ with $\lambda$ the rate of the
Kac operator. We also present a propagation of chaos result for the partially
thermostated Kac model in [14].


title:
Low-field electron mobility of InSb nanowires: Numerical efforts to
  larger cross sections

abstract:
  Within the framework of Boltzmann equation, we present a $\mathbf{k\cdot p}$
theory based study for the low-field mobilities of InSb nanowires (InSb NWs)
with relatively large cross sectional sizes (with diameters up to 51.8 nm). For
such type of large size nanowires, the intersubband electron-phonon scattering
is of crucial importance to affect the scattering rate and then the mobility.
In our simulation, the lowest 15 electron subbands and 50 transverse modes of
phonons are carefully accounted for. We find that, up to the 51.84 nm diameter,
the mobility monotonously increases with the diameter, not yet showing any
saturated behavior. We also find that, while the bulk InSb mobility is
considerably higher than the bulk Si, the small size (e.g. $\sim 3$ nm
diameter) nanowires from both materials have similar magnitude of mobilities.
This implies, importantly, that the mobility of the InSb NWs would decrease
faster than the SiNWs as we reduce the cross sectional size of the nanowires.


title:
The Processing Using Memory Paradigm:In-DRAM Bulk Copy, Initialization,
  Bitwise AND and OR

abstract:
  In existing systems, the off-chip memory interface allows the memory
controller to perform only read or write operations. Therefore, to perform any
operation, the processor must first read the source data and then write the
result back to memory after performing the operation. This approach consumes
high latency, bandwidth, and energy for operations that work on a large amount
of data. Several works have proposed techniques to process data near memory by
adding a small amount of compute logic closer to the main memory chips. In this
article, we describe two techniques proposed by recent works that take this
approach of processing in memory further by exploiting the underlying operation
of the main memory technology to perform more complex tasks. First, we describe
RowClone, a mechanism that exploits DRAM technology to perform bulk copy and
initialization operations completely inside main memory. We then describe a
complementary work that uses DRAM to perform bulk bitwise AND and OR operations
inside main memory. These two techniques significantly improve the performance
and energy efficiency of the respective operations.


title:
Understanding and Exploiting Design-Induced Latency Variation in Modern
  DRAM Chips

abstract:
  Variation has been shown to exist across the cells within a modern DRAM chip.
We empirically demonstrate a new form of variation that exists within a real
DRAM chip, induced by the design and placement of different components in the
DRAM chip. Our goals are to understand design-induced variation that exists in
real, state-of-the-art DRAM chips, exploit it to develop low-cost mechanisms
that can dynamically find and use the lowest latency at which to operate a DRAM
chip reliably, and, thus, improve overall system performance while ensuring
reliable system operation.
  To this end, we first experimentally demonstrate and analyze designed-induced
variation in modern DRAM devices by testing and characterizing 96 DIMMs (768
DRAM chips). Our characterization identifies DRAM regions that are vulnerable
to errors, if operated at lower latency, and finds consistency in their
locations across a given DRAM chip generation, due to design-induced variation.
Based on our extensive experimental analysis, we develop two mechanisms that
reliably reduce DRAM latency. First, DIVA Profiling uses runtime profiling to
dynamically identify the lowest DRAM latency that does not introduce failures.
DIVA Profiling exploits design-induced variation and periodically profiles only
the vulnerable regions to determine the lowest DRAM latency at low cost. Our
second mechanism, DIVA Shuffling, shuffles data such that values stored in
vulnerable regions are mapped to multiple error-correcting code (ECC)
codewords. Combined together, our two mechanisms reduce read/write latency by
40.0%/60.5%, which translates to an overall system performance improvement of
14.7%/13.7%/13.8% (in 2-/4-/8-core systems) across a variety of workloads,
while ensuring reliable operation.


title: Puzzle of the $\Lambda_c$ spectrum

abstract:
  There is a puzzle in the $\Lambda_c^+$ family, i.e., one member with
$J^P=3/2^+$ is missing in a $L=2$ multiplet which the heavy quark effective
theory predicts, and $J^P$'s of $\Lambda_c(2765)^+$ and $\Lambda_c(2940)^+$ are
unknown. Using a light diquark picture to calculate baryon masses, we study
possible assignments of two $\Lambda_c$'s with unknown $J^P$ and the missing
$\Lambda_c^+$ with $3/2^+$ for $L=2$, and we find the most probable possibility
that the peak corresponding to $\Lambda_c(2880)^+$ actually includes a missing
member with spin $3/2^+$ for $L=2$ and that quantum numbers of
$\Lambda_c(2765)^+$ and $\Lambda_c(2940)^+$ are $2S(1/2^+)$ and $2P(1/2^-)$,
respectively.


title:
Impedance control of a cable-driven series elastic actuator with the
  2-DOF control structure

abstract:
  Series elastic actuators (SEAs) are growingly important in physical
human-robot interaction (HRI) due to their inherent safety and compliance.
Cable-driven SEAs also allow flexible installation and remote torque
transmission, etc. However, there are still challenges for the impedance
control of cable-driven SEAs, such as the reduced bandwidth caused by the
elastic component, and the performance balance between reference tracking and
robustness. In this paper, a velocity sourced cable-driven SEA has been set up.
Then, a stabilizing 2 degrees of freedom (2-DOF) control approach was designed
to separately pursue the goals of robustness and torque tracking. Further, the
impedance control structure for human-robot interaction was designed and
implemented with a torque compensator. Both simulation and practical
experiments have validated the efficacy of the 2-DOF method for the control of
cable-driven SEAs.


title: Termination of Monotone Programs

abstract:
  We present an efficient approach to prove termination of monotone programs
with integer variables, an expressive class of loops that is often encountered
in computer programs. Our approach is based on a lightweight static analysis
method and takes advantage of simple %nice properties of monotone functions.
Our preliminary implementation %beats shows that our tool has an advantage over
existing tools and can prove termination for a high percentage of loops for a
class of benchmarks.


title:
A Theoretical Study of The Relationship Between Whole An ELM Network and
  Its Subnetworks

abstract:
  A biological neural network is constituted by numerous subnetworks and
modules with different functionalities. For an artificial neural network, the
relationship between a network and its subnetworks is also important and useful
for both theoretical and algorithmic research, i.e. it can be exploited to
develop incremental network training algorithm or parallel network training
algorithm. In this paper we explore the relationship between an ELM neural
network and its subnetworks. To the best of our knowledge, we are the first to
prove a theorem that shows an ELM neural network can be scattered into
subnetworks and its optimal solution can be constructed recursively by the
optimal solutions of these subnetworks. Based on the theorem we also present
two algorithms to train a large ELM neural network efficiently: one is a
parallel network training algorithm and the other is an incremental network
training algorithm. The experimental results demonstrate the usefulness of the
theorem and the validity of the developed algorithms.


title:
Generalized Haar Filter based Deep Networks for Real-Time Object
  Detection in Traffic Scene

abstract:
  Vision-based object detection is one of the fundamental functions in numerous
traffic scene applications such as self-driving vehicle systems and advance
driver assistance systems (ADAS). However, it is also a challenging task due to
the diversity of traffic scene and the storage, power and computing source
limitations of the platforms for traffic scene applications. This paper
presents a generalized Haar filter based deep network which is suitable for the
object detection tasks in traffic scene. In this approach, we first decompose a
object detection task into several easier local regression tasks. Then, we
handle the local regression tasks by using several tiny deep networks which
simultaneously output the bounding boxes, categories and confidence scores of
detected objects. To reduce the consumption of storage and computing resources,
the weights of the deep networks are constrained to the form of generalized
Haar filter in training phase. Additionally, we introduce the strategy of
sparse windows generation to improve the efficiency of the algorithm. Finally,
we perform several experiments to validate the performance of our proposed
approach. Experimental results demonstrate that the proposed approach is both
efficient and effective in traffic scene compared with the state-of-the-art.