title: Information-theoretic thresholds from the cavity method

abstract:
  Vindicating a sophisticated but non-rigorous physics approach called the
cavity method, we establish a formula for the mutual information in statistical
inference problems induced by random graphs and we show that the mutual
information holds the key to understanding certain important phase transitions
in random graph models. We work out several concrete applications of these
general results. For instance, we pinpoint the exact condensation phase
transition in the Potts antiferromagnet on the random graph, thereby improving
prior approximate results [Contucci et al.: Communications in Mathematical
Physics 2013]. Further, we prove the conjecture from [Krzakala et al.: PNAS
2007] about the condensation phase transition in the random graph coloring
problem for any number $q\geq3$ of colors. Moreover, we prove the conjecture on
the information-theoretic threshold in the disassortative stochastic block
model [Decelle et al.: Phys. Rev. E 2011]. Additionally, our general result
implies the conjectured formula for the mutual information in Low-Density
Generator Matrix codes [Montanari: IEEE Transactions on Information Theory
2005].


title:
Derivation of Higher Dimensional Periodic Recurrence Equations by Nested
  Structure of Complex Numbers

abstract:
  In this paper, we give a procedure for derivation of higher dimensional
periodic recurrence equations(PREs) by nested structure of complex numbers.


title: Constraints on atmospheric charmed-meson production from IceCube

abstract:
  At very-high energies (100 TeV - 1 PeV), the small value of Bjorken-x
($\le10^{-3}-10^{-7}$) at which the parton distribution functions are evaluated
makes the calculation of charm quark production very difficult. The charm quark
has mass ($\sim$1.5$\pm$0.2 GeV) significantly above the $\Lambda$$_{QCD}$
scale ($\sim$200 MeV), and therefore its production is perturbatively
calculable. However, the uncertainty in the data and the calculations cannot
exclude some smaller non-perturbative contribution. To evaluate the prompt
neutrino flux, one needs to know the charm production cross-section in pN ->
c$\bar{c}$ X, and hadronization of charm particles. This contribution briefly
discusses computation of prompt neutrino flux and presents the strongest limit
on prompt neutrino flux from IceCube.


title: Gaussian Processes for Survival Analysis

abstract:
  We introduce a semi-parametric Bayesian model for survival analysis. The
model is centred on a parametric baseline hazard, and uses a Gaussian process
to model variations away from it nonparametrically, as well as dependence on
covariates. As opposed to many other methods in survival analysis, our
framework does not impose unnecessary constraints in the hazard rate or in the
survival function. Furthermore, our model handles left, right and interval
censoring mechanisms common in survival analysis. We propose a MCMC algorithm
to perform inference and an approximation scheme based on random Fourier
features to make computations faster. We report experimental results on
synthetic and real data, showing that our model performs better than competing
models such as Cox proportional hazards, ANOVA-DDP and random survival forests.


title: Constructing Tight Gabor Frames Using CAZAC Sequences

abstract:
  The construction of finite tight Gabor frames plays an important role in many
applications. These applications include significant ones in signal and image
processing. We explore when constant amplitude zero autocorrelation (CAZAC)
sequences can be used to generate tight Gabor frames. The main theorem uses
Janssen's representation and the zeros of the discrete periodic ambiguity
function to give necessary and sufficient conditions for determining whether
any Gabor frame is tight. The relevance of the theorem depends significantly on
the construction of examples. These examples are necessarily intricate, and to
a large extent, depend on CAZAC sequences. Finally, we present an alternative
method for determining whether a Gabor system yields a tight frame. This
alternative method does not prove tightness using the main theorem, but instead
uses the Gram matrix of the Gabor system.


title: Developments in Maximum Likelihood Unit Root Tests

abstract:
  The exact maximum likelihood estimate (MLE) provides a test statistic for the
unit root test that is more powerful \citep[p. 577]{Fuller96} than the usual
least squares approach. In this paper a new derivation is given for the
asymptotic distribution of this test statistic that is simpler and more direct
than the previous method. The response surface regression method is used to
obtain a fast algorithm that computes accurate finite-sample critical values.
This algorithm is available in the R package {\tt mleur} that is available on
CRAN. The empirical power of the new test is shown to be much better than the
usual test not only in the normal case but also for innovations generated from
an infinite variance stable distribution as well as for innovations generated
from a GARCH$(1,1)$ process.


title: First Measurement of Neutrino Interactions in MicroBooNE

abstract:
  The MicroBooNE detector has recently completed its first year of neutrino
beam data-taking in the Booster Neutrino Beam at Fermilab, having collected
approximately half of its intended data ($3.4\times10^{20}$ of
$6.6\times10^{20}$ protons on target). We present kinematic distributions of
neutrino interactions observed from a small subset of this data (equivalent to
$5\times10^{19}$ protons on target), both as a first step towards a
charged-current muon neutrino cross-section on argon, and as an exploration of
the capabilities and operational challenges of large liquid argon time
projection chambers as neutrino detectors. These distributions have been
assessed using fully automated event selection and reconstruction.


title: LArIAT: Worlds First Pion-Argon Cross-Section

abstract:
  The LArIAT experiment has performed the world's first measurement of the
total charged-current pion cross-section on an argon target, using the
repurposed ArgoNeuT detector in the Fermilab test beam. Presented here are the
results of that measurement, along with an overview of the LArIAT experiment
and details of the LArIAT collaboration's plans for future measurements.


title: Learning Deep Embeddings with Histogram Loss

abstract:
  We suggest a loss for learning deep embeddings. The new loss does not
introduce parameters that need to be tuned and results in very good embeddings
across a range of datasets and problems. The loss is computed by estimating two
distribution of similarities for positive (matching) and negative
(non-matching) sample pairs, and then computing the probability of a positive
pair to have a lower similarity score than a negative pair based on the
estimated similarity distributions. We show that such operations can be
performed in a simple and piecewise-differentiable manner using 1D histograms
with soft assignment operations. This makes the proposed loss suitable for
learning deep embeddings using stochastic optimization. In the experiments, the
new loss performs favourably compared to recently proposed alternatives.


title:
Lower bounds for the blow-up time of the heat equation in convex domains
  with local nonlinear boundary conditions

abstract:
  This paper studies the lower bound for the blow-up time $T^{*}$ of the heat
equation $u_t=\Delta u$ in a bounded convex domain $\Omega$ in
$\mathbb{R}^{N}(N\geq 2)$ with positive initial data $u_{0}$ and a local
nonlinear Neumann boundary condition: the normal derivative $\partial
u/\partial n=u^{q}$ on partial boundary $\Gamma_1\subseteq\partial\Omega$ for
some $q>1$, while $\partial u/\partial n=0$ on the other part. For any
$\alpha<\frac{1}{N-1}$, we obtain a lower bound for $T^{*}$ which is of order
$|\Gamma_{1}|^{-\alpha}$ as $|\Gamma_{1}|\rightarrow 0^{+}$, where
$|\Gamma_{1}|$ represents the surface area of $\Gamma_{1}$. As
$|\Gamma_{1}|\rightarrow 0^{+}$, this result significantly improves the
previous lower bound $\ln\big(|\Gamma_1|^{-1}\big)$ and is almost optimal in
dimension $N=2$, since the existing upper bound is of order $|\Gamma_{1}|^{-1}$
as $|\Gamma_{1}|\rightarrow 0^{+}$. In addition, the optimal asymptotic order
of the lower bound for $T^{*}$ on $q$ (as $q\rightarrow 1^{+}$) and on $M_{0}$
(as $M_{0}\rightarrow 0^{+}$) are obtained, where $M_{0}$ denotes the maximum
of $u_{0}$.


title: Unitary groups and ramified extensions

abstract:
  We classify all non-degenerate skew-hermitian forms defined over certain
local rings, not necessarily commutative, and study some of the fundamental
properties of the associated unitary groups, including their orders when the
ring in question is finite.


title: A Computational Framework for Automation of Point Defect Calculations

abstract:
  A complete and rigorously validated open-source Python framework to automate
point defect calculations using density functional theory has been developed.
The framework provides an effective and efficient method for defect structure
generation, and creation of simple yet customizable workflows to analyze defect
calculations. The package provides the capability to compute widely-accepted
correction schemes to overcome finite-size effects, including (1) potential
alignment, (2) image-charge correction, and (3) band filling correction to
shallow defects. Using Si, ZnO and In$_2$O$_3$ as test examples, we demonstrate
the package capabilities and validate the methodology.


title: Hyperbolic decay time series

abstract:
  Hyperbolic decay time series such as, fractional Gaussian noise (FGN) or
fractional autoregressive moving-average (FARMA) process, each exhibit two
distinct types of behaviour: strong persistence or antipersistence. Beran
(1994) characterized the family of strongly persistent time series. A more
general family of hyperbolic decay time series is introduced and its basic
properties are characterized in terms of the autocovariance and spectral
density functions. The random shock and inverted form representations are
derived. It is shown that every strongly persistent series is the dual of an
antipersistent series and vice versa. The asymptotic generalized variance of
hyperbolic decay time series with unit innovation variance is shown to be
infinite which implies that the variance of the minimum mean-square error
one-step linear predictor using the last $k$ observations decays slowly to the
innovation variance as $k$ gets large.


title: Geometric complexity theory and matrix powering

abstract:
  Valiant's famous determinant versus permanent problem is the flagship problem
in algebraic complexity theory. Mulmuley and Sohoni (Siam J Comput 2001, 2008)
introduced geometric complexity theory, an approach to study this and related
problems via algebraic geometry and representation theory. Their approach works
by multiplying the permanent polynomial with a high power of a linear form (a
process called padding) and then comparing the orbit closures of the
determinant and the padded permanent. This padding was recently used heavily to
show no-go results for the method of shifted partial derivatives (Efremenko,
Landsberg, Schenck, Weyman, 2016) and for geometric complexity theory
(Ikenmeyer Panova, FOCS 2016 and B\"urgisser, Ikenmeyer Panova, FOCS 2016).
Following a classical homogenization result of Nisan (STOC 1991) we replace the
determinant in geometric complexity theory with the trace of a variable matrix
power. This gives an equivalent but much cleaner homogeneous formulation of
geometric complexity theory in which the padding is removed. This radically
changes the representation theoretic questions involved to prove complexity
lower bounds. We prove that in this homogeneous formulation there are no orbit
occurrence obstructions that prove even superlinear lower bounds on the
complexity of the permanent. This is the first no-go result in geometric
complexity theory that rules out superlinear lower bounds in some model.
Interestingly---in contrast to the determinant---the trace of a variable matrix
power is not uniquely determined by its stabilizer.


title: The Local Ginzburg-Rallis Model Over Complex Field

abstract:
  We consider the local Ginzburg-Rallis model over complex field. We show that
the multiplicity is always 1 for a majority of the generic representations. We
also have partial results on the real case for general generic representations.
This is a sequel work of [Wan15] and [Wan16] on which we considered the p-adic
case and the real case for tempered representations.


title: Multidimensional Binary Search for Contextual Decision-Making

abstract:
  We consider a multidimensional search problem that is motivated by questions
in contextual decision-making, such as dynamic pricing and personalized
medicine. Nature selects a state from a $d$-dimensional unit ball and then
generates a sequence of $d$-dimensional directions. We are given access to the
directions, but not access to the state. After receiving a direction, we have
to guess the value of the dot product between the state and the direction. Our
goal is to minimize the number of times when our guess is more than $\epsilon$
away from the true answer. We construct a polynomial time algorithm that we
call Projected Volume achieving regret $O(d\log(d/\epsilon))$, which is optimal
up to a $\log d$ factor. The algorithm combines a volume cutting strategy with
a new geometric technique that we call cylindrification.


title: On the non-Kolmogorov nature of flare-productive solar active regions

abstract:
  A magnetic power spectral analysis is performed on 53 solar active regions,
observed from August 2011 to July 2012. Magnetic field data obtained from the
Helioseismic and Magnetic Imager, inverted as Active Region Patches, are used
to study the evolution of the magnetic power index as each region rotates
across the solar disk. Active regions are classified based on the number, and
sizes, of solar flares they produce, in order to study the relationship between
flare productivity and the magnetic power index. The choice of window size and
inertial range plays a key role in determining the correct magnetic power
index. The overall distribution of magnetic power indices has a range of
$1.0-2.5$. Flare-quiet regions peak at a value of 1.6, however flare-productive
regions peak at a value of 2.2. Overall, the histogram of the distribution of
power indices of flare-productive active regions is well separated from
flare-quiet active regions. Only 12\% of flare-quiet regions exhibit an index
greater than 2, whereas 90\% of flare-productive regions exhibit an index
greater than 2. Flare-quiet regions exhibit a high temporal variance (i.e, the
index fluctuates between high and low values), whereas flare-productive regions
maintain an index greater than 2 for several days. This shows the importance of
including the temporal evolution of active regions in flare prediction studies,
and highlights the potential of a 2-3 day prediction window for space weather
applications.


title: New applications of Arak's inequalities to the Littlewood-Offord problem

abstract:
  Let $X,X_1,\ldots,X_n$ be independent identically distributed random
variables. In this paper we study the behavior of concentration functions of
weighted sums $\sum_{k=1}^{n}X_ka_k $ with respect to the arithmetic structure
of coefficients $a_k$ in the context of the Littlewood--Offord problem. In
recent papers of Eliseeva, G\"otze and Zaitsev, we discussed the relations
between the inverse principles stated by Nguyen, Tao and Vu and similar
principles formulated by Arak in his papers from the 1980's. In this paper, we
will derive some more general and more precise consequences of Arak's
inequalities providing new results in the context of the Littlewood-Offord
problem.


title:
Topological phases of parafermions: a model with exactly-solvable ground
  states

abstract:
  Parafermions are emergent excitations that generalize Majorana fermions and
can also realize topological order. In this paper we present a non-trivial and
quasi-exactly-solvable model for a chain of parafermions in a topological
phase. We compute and characterize the ground-state wave-functions, which are
matrix-product states and have a particularly elegant interpretation in terms
of Fock parafermions, reflecting the factorized nature of the ground states.
Using these wavefunctions, we demonstrate analytically several signatures of
topological order. Our study provides a starting point for the non-approximate
study of topological one-dimensional parafermionic chains with
spatial-inversion and time-reversal symmetry in the absence of strong edge
modes.


title: Architecture and Function of Mechanosensitive Membrane Protein Lattices

abstract:
  Experiments have revealed that membrane proteins can form two-dimensional
clusters with regular translational and orientational protein arrangements,
which may allow cells to modulate protein function. However, the physical
mechanisms yielding supramolecular organization and collective function of
membrane proteins remain largely unknown. Here we show that bilayer-mediated
elastic interactions between membrane proteins can yield regular and
distinctive lattice architectures of protein clusters, and may provide a link
between lattice architecture and lattice function. Using the mechanosensitive
channel of large conductance (MscL) as a model system, we obtain relations
between the shape of MscL and the supramolecular architecture of MscL lattices.
We predict that the tetrameric and pentameric MscL symmetries observed in
previous structural studies yield distinct lattice architectures of MscL
clusters and that, in turn, these distinct MscL lattice architectures yield
distinct lattice activation barriers. Our results suggest general physical
mechanisms linking protein symmetry, the lattice architecture of membrane
protein clusters, and the collective function of membrane protein lattices.

categories: q-bio.BM cond-mat.soft physics.bio-ph q-bio.SC


title: Network cloning using DNA barcodes

abstract:
  The ability to measure or manipulate network connectivity is the main
challenge in the field of connectomics. Recently, a set of approaches has been
developed that takes advantage of next generation DNA sequencing to scan
connections between neurons into a set of DNA barcodes. Individual DNA
sequences called markers represent single neurons, while pairs of markers,
called barcodes contain information about connections. Here we propose a
strategy for 'copying' or 'cloning' connectivity contained in barcodes into a
clean slate tabula rasa network. We show that a one marker one cell (OMOC)
rule, which forces all markers with the same sequence to condense into the same
neuron, leads to fast and reliable formation of desired connectivity in a new
network. We show that OMOC rule yields convergence in a number of steps given
by a power law function of the network size. We thus propose that copying
network connectivity from one network to another is theoretically possible.


title: A Bayesian Analysis of the Ages of Four Open Clusters

abstract:
  In this paper we apply a Bayesian technique to determine the best fit of
stellar evolution models to find the main sequence turn off age and other
cluster parameters of four intermediate-age open clusters: NGC 2360, NGC 2477,
NGC 2660, and NGC 3960. Our algorithm utilizes a Markov chain Monte Carlo
technique to fit these various parameters, objectively finding the best-fit
isochrone for each cluster. The result is a high-precision isochrone fit. We
compare these results with the those of traditional "by-eye" isochrone fitting
methods. By applying this Bayesian technique to NGC 2360, NGC 2477, NGC 2660,
and NGC 3960, we determine the ages of these clusters to be 1.35 +/- 0.05, 1.02
+/- 0.02, 1.64 +/- 0.04, and 0.860 +/- 0.04 Gyr, respectively. The results of
this paper continue our effort to determine cluster ages to higher precision
than that offered by these traditional methods of isochrone fitting.


title:
Bilayer-thickness-mediated interactions between integral membrane
  proteins

abstract:
  Hydrophobic thickness mismatch between integral membrane proteins and the
surrounding lipid bilayer can produce lipid bilayer thickness deformations.
Experiment and theory have shown that protein-induced lipid bilayer thickness
deformations can yield energetically favorable bilayer-mediated interactions
between integral membrane proteins, and large-scale organization of integral
membrane proteins into protein clusters in cell membranes. Within the continuum
elasticity theory of membranes, the energy cost of protein-induced bilayer
thickness deformations can be captured by considering compression and expansion
of the bilayer hydrophobic core, membrane tension, and bilayer bending,
resulting in biharmonic equilibrium equations describing the shape of lipid
bilayers for a given set of bilayer-protein boundary conditions. Here we
develop a combined analytic and numerical methodology for the solution of the
equilibrium elastic equations associated with protein-induced lipid bilayer
deformations. Our methodology allows accurate prediction of thickness-mediated
protein interactions for arbitrary protein symmetries at arbitrary protein
separations and relative orientations. We provide exact analytic solutions for
cylindrical integral membrane proteins with constant and varying hydrophobic
thickness, and develop perturbative analytic solutions for non-cylindrical
protein shapes. We complement these analytic solutions, and assess their
accuracy, by developing both finite element and finite difference numerical
solution schemes. Taken together, the work presented here puts into place an
analytic and numerical framework which allows calculation of bilayer-mediated
elastic interactions between integral membrane proteins for the complicated
protein shapes suggested by structural biology and at the small protein
separations most relevant for the crowded membrane environments provided by
living cells.


title:
Context-aware System Service Call-oriented Symbolic Execution of Android
  Framework with Application to Exploit Generation

abstract:
  Android Framework is a layer of software that exists in every Android system
managing resources of all Android apps. A vulnerability in Android Framework
can lead to severe hacks, such as destroying user data and leaking private
information. With tens of millions of Android devices unpatched due to Android
fragmentation, vulnerabilities in Android Framework certainly attract attackers
to exploit them. So far, enormous manual effort is needed to craft such
exploits. To our knowledge, no research has been done on automatic generation
of exploits that take advantage of Android Framework vulnerabilities. We make a
first step towards this goal by applying symbolic execution of Android
Framework to finding bugs and generating exploits. Several challenges have been
raised by the task. (1) The information of an app flows to Android Framework in
multiple intricate steps, making it difficult to identify symbolic inputs. (2)
Android Framework has a complex initialization phase, which exacerbates the
state space explosion problem. (3) A straightforward design that builds the
symbolic executor as a layer inside the Android system will not work well: not
only does the implementation have to ensure the compatibility with the Android
system, but it needs to be maintained whenever Android gets updated. We present
novel ideas and techniques to resolve the challenges, and have built the first
system for symbolic execution of Android Framework. It fundamentally changes
the state of the art in exploit generation on the Android system, and has been
applied to constructing new techniques for finding vulnerabilities.


title: Initialization and Coordinate Optimization for Multi-way Matching

abstract:
  We consider the problem of consistently matching multiple sets of elements to
each other, which is a common task in fields such as computer vision. To solve
the underlying NP-hard objective, existing methods often relax or approximate
it, but end up with unsatisfying empirical performance due to a misaligned
objective. We propose a coordinate update algorithm that directly optimizes the
target objective. By using pairwise alignment information to build an
undirected graph and initializing the permutation matrices along the edges of
its Maximum Spanning Tree, our algorithm successfully avoids bad local optima.
Theoretically, with high probability our algorithm guarantees an optimal
solution under reasonable noise assumptions. Empirically, our algorithm
consistently and significantly outperforms existing methods on several
benchmark tasks on real datasets.


title: Formation and properties of astrophysical carbonaceous dust

abstract:
  The classical theory of grain nucleation suffers from both theoretical and
predictive deficiencies. We strive to alleviate these deficiencies in our
understanding of dust formation and growth by utilizing an atomistic model of
nucleation. Carbon cluster geometries are determined with a set of global
minimization algorithms. Using density functional theory, the binding energies
of carbon clusters from $n=2$ to $n=99$ are then calculated. These energies are
used to calculate the critical size and nucleation rate of carbon clusters.
  We find that the critical cluster size is largely determined by the changes
in geometry of the clusters. Clusters with size $n=27$ and $n=8$, roughly
corresponding to the transition from ring-to-fullerene geometry and
chain-to-ring geometry respectively, are the critical sizes across the range of
temperature and saturation where nucleation is significant. In contrast to the
classical theory, nucleation is enhanced at low-temperatures, and suppressed at
high temperatures. These results will be applied to a modified chemical
evolution code using results from supernova simulations.


title: Below all subsets for Minimal Connected Dominating Set

abstract:
  A vertex subset $S$ in a graph $G$ is a dominating set if every vertex not
contained in $S$ has a neighbor in $S$. A dominating set $S$ is a connected
dominating set if the subgraph $G[S]$ induced by $S$ is connected. A connected
dominating set $S$ is a minimal connected dominating set if no proper subset of
$S$ is also a connected dominating set. We prove that there exists a constant
$\varepsilon > 10^{-50}$ such that every graph $G$ on $n$ vertices has at most
$O(2^{(1-\varepsilon)n})$ minimal connected dominating sets. For the same
$\varepsilon$ we also give an algorithm with running time
$2^{(1-\varepsilon)n}\cdot n^{O(1)}$ to enumerate all minimal connected
dominating sets in an input graph $G$.


title:
Graphs of curves on infinite-type surfaces with mapping class group
  actions

abstract:
  We study when the mapping class group of an infinite-type surface $S$ admits
an action with unbounded orbits on a connected graph whose vertices are simple
closed curves on $S$. We introduce a topological invariant for infinite-type
surfaces that determines in many cases whether there is such an action. This
allows us to conclude that, as non-locally compact topological groups, many big
mapping class groups have nontrivial coarse geometry in the sense of Rosendal.


title: Symmetry and size of membrane protein polyhedral nanoparticles

abstract:
  In recent experiments [T. Basta et al., Proc. Natl. Acad. Sci. U.S.A. 111,
670 (2014)] lipids and membrane proteins were observed to self-assemble into
membrane protein polyhedral nanoparticles (MPPNs) with a well-defined
polyhedral protein arrangement and characteristic size. We develop a model of
MPPN self-assembly in which the preferred symmetry and size of MPPNs emerge
from the interplay of protein-induced lipid bilayer deformations, topological
defects in protein packing, and thermal effects. With all model parameters
determined directly from experiments, our model correctly predicts the observed
symmetry and size of MPPNs. Our model suggests how key lipid and protein
properties can be modified to produce a range of MPPN symmetries and sizes in
experiments.


title: Sampling and Estimation for (Sparse) Exchangeable Graphs

abstract:
  Sparse exchangeable graphs on $\mathbb{R}_+$, and the associated graphex
framework for sparse graphs, generalize exchangeable graphs on $\mathbb{N}$,
and the associated graphon framework for dense graphs. We develop the graphex
framework as a tool for statistical network analysis by identifying the
sampling scheme that is naturally associated with the models of the framework,
and by introducing a general consistent estimator for the parameter (the
graphex) underlying these models. The sampling scheme is a modification of
independent vertex sampling that throws away vertices that are isolated in the
sampled subgraph. The estimator is a dilation of the empirical graphon
estimator, which is known to be a consistent estimator for dense exchangeable
graphs; both can be understood as graph analogues to the empirical distribution
in the i.i.d. sequence setting. Our results may be viewed as a generalization
of consistent estimation via the empirical graphon from the dense graph regime
to also include sparse graphs.


title: Input-Delay Compensation in a Robust Adaptive Control Framework

abstract:
  A modification to the ${\cal L}_1$ control framework for uncertain systems
with actuator delay is presented. Specifically, a time delay is introduced in
the control input of the state predictor to compensate for the destabilizing
effect of input delay in the plant. For this modified framework, the analysis
shows that the output of the adaptive system closely follows the behavior of a
suitably defined, nonadaptive, stable reference system provided that a
delay-dependent stability condition is satisfied and the adaptive gain is
chosen sufficiently large. The set of combinations of input delay and
compensation delay for which the stability condition is satisfied contains an
open set of pairs of positive values provided that a filter bandwidth,
characteristic of ${\cal L}_1$ adaptive control is chosen sufficiently large.
The efficacy of the delay compensation is illustrated by a simple example. A
numerical continuation is also performed to explore the stability region for a
case where this can be approximated a priori.


title: Weak ferromagnetism and short range polar order in NaMnF$_3$ thin films

abstract:
  The orthorhombically distorted perovskite NaMnF$_{3}$ has been predicted to
become ferroelectric if an $a=c$ distortion of the bulk $Pnma$ structure is
imposed. In order to test this prediction, NaMnF$_{3}$ thin films were grown on
SrTiO$_{3}$ (001) single crystal substrates via molecular beam epitaxy. The
best films were smooth and single phase with four different twin domains.
In-plane magnetization measurements revealed the presence of antiferromagnetic
ordering with weak ferromagnetism below the N\'eel temperature $T_N=66$ K. For
the dielectric studies, NaMnF$_{3}$ films were grown on a 30 nm SrRuO$_{3}$
(001) layer used as a bottom electrode grown via pulsed laser deposition. The
complex permittivity as a function of frequency indicated a strong Debye-like
relaxation contribution characterized by a distribution of relaxation times. A
power-law divergence of the characteristic relaxation time revealed an
order-disorder phase transition at 8 K. The slow relaxation dynamics indicated
the formation of super-dipoles (superparaelectric moments) that extend over
several unit cells, similar to polar nanoregions of relaxor ferroelectrics.


title: Rapidity correlations test stochastic hydrodynamics

abstract:
  We show that measurements of the rapidity dependence of transverse momentum
correlations can be used to determine the characteristic time $\tau_{\pi}$ that
dictates the rate of isotropization of the stress energy tensor, as well as the
shear viscosity $\nu = \eta/sT$. We formulate methods for computing these
correlations using second order dissipative hydrodynamics with noise. Current
data are consistent with $\tau_{\pi}/\nu \sim 10$ but targeted measurements can
improve this precision.


title: Deep Convolutional Neural Network Design Patterns

abstract:
  Recent research in the deep learning field has produced a plethora of new
architectures. At the same time, a growing number of groups are applying deep
learning to new applications. Some of these groups are likely to be composed of
inexperienced deep learning practitioners who are baffled by the dizzying array
of architecture choices and therefore opt to use an older architecture (i.e.,
Alexnet). Here we attempt to bridge this gap by mining the collective knowledge
contained in recent deep learning research to discover underlying principles
for designing neural network architectures. In addition, we describe several
architectural innovations, including Fractal of FractalNet network, Stagewise
Boosting Networks, and Taylor Series Networks (our Caffe code and prototxt
files is available at https://github.com/iPhysicist/CNNDesignPatterns). We hope
others are inspired to build on our preliminary work.


title:
Unit Groups of Representation Rings and their Ghost Rings as Inflation
  Functors

abstract:
  The theory of biset functors developed by Serge Bouc has been instrumental in
the study of the unit group of the Burnside ring of a finite group, in
particular for the case of p-groups. The ghost ring of the Burnside ring
defines an inflation functor, and becomes a useful tool in studying the
Burnside ring functor itself. We are interested in studying the unit group of
another representation ring: the trivial source ring of a finite group. In this
article, we show how the unit groups of the trivial source ring and its
associated ghost ring define inflation functors. Since the trivial source ring
is often seen as connecting the Burnside ring to the character ring and Brauer
character ring of a finite group, we study all these representation rings at
the same time. We point out that restricting all of these representation rings'
unit groups to their torsion subgroups also give inflation functors, which we
can completely determine in the case of the character ring and Brauer character
ring.


title: Mass Loss Evolution in the EUV Low Corona from SDO/AIA Data

abstract:
  We carry out an analysis of the evacuated mass from three coronal dimming
regions observed by the {\it Atmospheric Imaging Assembly} (AIA) on board the
{\it Solar Dynamics Observatory}. The three events are unambiguously identified
with white-light coronal mass ejections (CMEs) associated in turn with surface
activity of diverse nature: an impulsive (M-class) flare, a weak (B-class)
flare and a filament eruption without a flare. The use of three AIA coronal
passbands allows applying a differential emission measure technique to define
the dimming regions and identify their evacuated mass through the analysis of
the electronic density depletion associated to the eruptions. The temporal
evolution of the mass loss from the three dimmings can be approximated by an
exponential equation followed by a linear fit. We determine the mass of the
associated CMEs from COR2 data. The results show that the evacuated masses from
the low corona represent a considerable amount of the mass of the CMEs. We also
find that plasma is still being evacuated from the low corona at the time when
the CMEs reach the COR2 field of view. The temporal evolution of the angular
width of the CMEs, of the dimming regions in the low corona, and of the flux
registered by GOES in soft X-rays are all in close relation with the behavior
of mass evacuation from the low corona. We discuss the implications of our
findings toward a better understanding of the temporal evolution of several
parameters associated to the analyzed dimmings and CMEs.


title: Optical Flow Estimation using a Spatial Pyramid Network

abstract:
  We learn to compute optical flow by combining a classical spatial-pyramid
formulation with deep learning. This estimates large motions in a
coarse-to-fine approach by warping one image of a pair at each pyramid level by
the current flow estimate and computing an update to the flow. Instead of the
standard minimization of an objective function at each pyramid level, we train
one deep network per level to compute the flow update. Unlike the recent
FlowNet approach, the networks do not need to deal with large motions; these
are dealt with by the pyramid. This has several advantages. First, our Spatial
Pyramid Network (SPyNet) is much simpler and 96% smaller than FlowNet in terms
of model parameters. This makes it more efficient and appropriate for embedded
applications. Second, since the flow at each pyramid level is small (< 1
pixel), a convolutional approach applied to pairs of warped images is
appropriate. Third, unlike FlowNet, the learned convolution filters appear
similar to classical spatio-temporal filters, giving insight into the method
and how to improve it. Our results are more accurate than FlowNet on most
standard benchmarks, suggesting a new direction of combining classical flow
methods with deep learning.


title: An All-In-One Convolutional Neural Network for Face Analysis

abstract:
  We present a multi-purpose algorithm for simultaneous face detection, face
alignment, pose estimation, gender recognition, smile detection, age estimation
and face recognition using a single deep convolutional neural network (CNN).
The proposed method employs a multi-task learning framework that regularizes
the shared parameters of CNN and builds a synergy among different domains and
tasks. Extensive experiments show that the network has a better understanding
of face and achieves state-of-the-art result for most of these tasks.


title:
Quantizing Mishchenko-Fomenko subalgebras for centralizers via affine
  W-algebras

abstract:
  We use affine W-algebras to quantize Mishchenko-Fomenko subalgebras for
centralizers of nilpotent elements in simple Lie algebras under certain
assumptions that are satisfied for all cases in type A and all minimal
nilpotent cases outside type $E_8$.


title: Scale Holography

abstract:
  We present a new correspondence between a d-dimensional dynamical system and
a whole family of (d+1)-dimensional systems. This new scale-holographic
relation is built by the explicit introduction of a dimensionful constant which
determines the size of the additional dimension. Scale holography is
particularly useful for studying non-local theories, since the equivalent dual
system on the higher dimensional manifold can be made to be local, as we
illustrate with the specific example of the p-adic string.


title:
A cubic scaling algorithm for excited states calculations in
  particle-particle random phase approximation

abstract:
  The particle-particle random phase approximation (pp-RPA) has been shown to
be capable of describing double, Rydberg, and charge transfer excitations, for
which the conventional time-dependent density functional theory (TDDFT) might
not be suitable. It is thus desirable to reduce the computational cost of
pp-RPA so that it can be efficiently applied to larger molecules and even
solids. This paper introduces an $O(N^3)$ algorithm, where $N$ is the number of
orbitals, based on an interpolative separable density fitting technique and the
Jacobi-Davidson eigensolver to calculate a few low-lying excitations in the
pp-RPA framework. The size of the pp-RPA matrix can also be reduced by keeping
only a small portion of orbitals with orbital energy close to the Fermi energy.
This reduced system leads to a smaller prefactor of the cubic scaling
algorithm, while keeping the accuracy for the low-lying excitation energies.


title: ALMA band 8 continuum emission from Orion Source I

abstract:
  We have measured continuum flux densities of a high-mass protostar candidate,
a radio source I in the Orion KL region (Orion Source I) using the Atacama
Large Millimeter/Submillimeter Array (ALMA) at band 8 with an angular
resolution of 0.1". The continuum emission at 430, 460, and 490 GHz associated
with Source I shows an elongated structure along the northwest-southeast
direction perpendicular to the so-called low-velocity bipolar outflow. The
deconvolved size of the continuum source, 90 au times 20 au, is consistent with
those reported previously at other millimeter/submillimeter wavelength. The
flux density can be well fitted to the optically thick black-body spectral
energy distribution (SED), and the brightness temperature is evaluated to be
700-800 K. It is much lower than that in the case of proton-electron or H-
free-free radiations. Our data are consistent with the latest ALMA results by
Plambeck & Wright (2016), in which the continuum emission have been proposed to
arise from the edge-on circumstellar disk via thermal dust emission, unless the
continuum source consists of an unresolved structure with the smaller beam
filling factor.


title:
On the differentiability of solutions of stochastic evolution equations
  with respect to their initial values

abstract:
  In this article we study the differentiability of solutions of parabolic
semilinear stochastic evolution equations (SEEs) with respect to their initial
values. We prove that if the nonlinear drift coefficients and the nonlinear
diffusion coefficients of the considered SEEs are $n$-times continuously
Fr\'{e}chet differentiable, then the solutions of the considered SEEs are also
$n$-times continuously Fr\'{e}chet differentiable with respect to their initial
values. Moreover, a key contribution of this work is to establish suitable
enhanced regularity properties of the derivative processes of the considered
SEE in the sense that the dominating linear operator appearing in the SEE
smoothes the higher order derivative processes.


title:
Spectral Energy Distribution Mapping of Two Elliptical Galaxies on
  sub-kpc scales

abstract:
  We use high-resolution Herschel-PACS data of 2 nearby elliptical galaxies,
IC1459 & NGC2768 to characterize their dust and stellar content. IC1459 &
NGC2768 have an unusually large amount of dust for elliptical galaxies (1-3 x
10^5 Msun), this dust is also not distributed along the stellar content. Using
data from GALEX (ultraviolet) to PACS (far-infrared), we analyze the spectral
energy distribution (SED) of these galaxies with CIGALEMC as a function of the
projected position, binning images in 7.2" pixels. From this analysis, we
derive maps of SED parameters, such as the metallicity, the stellar mass, the
fraction of young star and the dust mass. The larger amount of dust in FIR maps
seems related in our model to a larger fraction of young stars which can reach
up to 4% in the dustier area. The young stellar population is fitted as a
recent (~ 0.5 Gyr) short burst of star formation for both galaxies. The
metallicities, which are fairly large at the center of both galaxies, decrease
with the radial distance with fairly steep gradient for elliptical galaxies.


title:
Regularity properties for solutions of infinite dimensional Kolmogorov
  equations in Hilbert spaces

abstract:
  In this article we establish regularity properties for solutions of infinite
dimensional Kolmogorov equations. We prove that if the nonlinear drift
coefficients, the nonlinear diffusion coefficients, and the initial conditions
of the considered Kolmogorov equations are $n$-times continuously Fr\'{e}chet
differentiable, then so are the generalized solutions at every positive time.
In addition, a key contribution of this work is to prove suitable enhanced
regularity properties for the derivatives of the generalized solutions of the
Kolmogorov equations in the sense that the dominating linear operator in the
drift coefficient of the Kolmogorov equation regularizes the higher order
derivatives of the solutions. Such enhanced regularity properties are of major
importance for establishing weak convergence rates for spatial and temporal
numerical approximations of stochastic partial differential equations.


title:
The Gaia-ESO Survey: the inner disk, intermediate-age open cluster
  Trumpler 23

abstract:
  Context: Trumpler 23 is a moderately populated, intermediate-age open cluster
within the solar circle at a Rgc ~6 kpc. It is in a crowded field very close to
the Galactic plane and the color-magnitude diagram shows significant field
contamination and possible differential reddening; it is a relatively
understudied cluster for these reasons, but its location makes it a key object
for determining Galactic abundance distributions.
  Aims: New data from the Gaia-ESO Survey enable the first ever radial velocity
and spectroscopic metallicity measurements for this cluster. We aim to use
velocities to isolate cluster members, providing more leverage for determining
cluster parameters.
  Methods: Gaia-ESO Survey data for 167 potential members have yielded radial
velocity measurements, which were used to determine the systemic velocity of
the cluster and membership of individual stars. Atmospheric parameters were
also used as a check on membership when available. Literature photometry was
used to re-determine cluster parameters based on radial velocity member stars
only; theoretical isochrones are fit in the V, V-I diagram. Cluster abundance
measurements of ten radial-velocity member stars with high-resolution
spectroscopy are presented for 24 elements. These abundances have been compared
to local disk stars, and where possible placed within the context of literature
gradient studies.
  Results: We find Trumpler 23 to have an age of 0.80 +/- 0.10 Gyr, significant
differential reddening with an estimated mean cluster E(V-I) of 1.02
+0.14/-0.09, and an apparent distance modulus of 14.15 +/- 0.20. We find an
average cluster metallicity of [Fe/H] = 0.14 +/- 0.03 dex, a solar [alpha/Fe]
abundance, and notably subsolar [s-process/Fe] abundances.


title:
HPVM: A Portable Virtual Instruction Set for Heterogeneous Parallel
  Systems

abstract:
  We describe a programming abstraction for heterogeneous parallel hardware,
designed to capture a wide range of popular parallel hardware, including GPUs,
vector instruction sets and multicore CPUs. Our abstraction, which we call
HPVM, is a hierarchical dataflow graph with shared memory and vector
instructions. We use HPVM to define both a virtual instruction set (ISA) and
also a compiler intermediate representation (IR). The virtual ISA aims to
achieve both functional portability and performance portability across
heterogeneous systems, while the compiler IR aims to enable effective code
generation and optimization for such systems.
  HPVM effectively supports all forms of parallelism used to achieve
computational speedups (as opposed to concurrency), including task parallelism,
coarse-grain data parallelism, fine-grain data parallelism, and pipelined
parallelism. HPVM also enables flexible scheduling and tiling: different nodes
in the dataflow graph can be mapped flexibly to different combinations of
compute units, and the graph hierarchy expresses memory tiling, essential for
achieving high performance on GPU and CPU targets.


title:
Emerging Wireless Technologies in the Internet of Things: a Comparative
  Study

abstract:
  The Internet of Things (IoT) incorporates multiple long-range, short-range,
and personal area wireless networks and technologies into the designs of IoT
applications. This enables numerous business opportunities in fields as diverse
as e-health, smart cities, smart homes, among many others. This research
analyses some of the major evolving and enabling wireless technologies in the
IoT. Particularly, it focuses on ZigBee, 6LoWPAN, Bluetooth Low Energy, LoRa,
and the different versions of Wi-Fi including the recent IEEE 802.11ah
protocol. The studies evaluate the capabilities and behaviours of these
technologies regarding various metrics including the data range and rate,
network size, RF Channels and Bandwidth, and power consumption. It is concluded
that there is a need to develop a multifaceted technology approach to enable
interoperable and secure communications in the IoT.


title: Quantile Reinforcement Learning

abstract:
  In reinforcement learning, the standard criterion to evaluate policies in a
state is the expectation of (discounted) sum of rewards. However, this
criterion may not always be suitable, we consider an alternative criterion
based on the notion of quantiles. In the case of episodic reinforcement
learning problems, we propose an algorithm based on stochastic approximation
with two timescales. We evaluate our proposition on a simple model of the TV
show, Who wants to be a millionaire.


title:
Illuminating the past 8 billion years of cold gas towards two
  gravitationally lensed quasars

abstract:
  Using the Boolardy Engineering Test Array of the Australian Square Kilometre
Array Pathfinder (ASKAP BETA), we have carried out the first $z = 0 - 1$ survey
for HI and OH absorption towards the gravitationally lensed quasars
PKSB1830$-$211 and MGJ0414$+$0534. Although we detected all previously reported
intervening systems towards PKSB1830$-$211, in the case of MGJ0414+0534 three
systems were not found, indicating that the original identifications may have
been confused with radio frequency interference. Given the sensitivity of our
data, we find that our detection yield is consistent with the expected
frequency of intervening HI systems estimated from previous surveys for 21-cm
emission in nearby galaxies and $z \sim 3$ damped Lyman $\alpha$ absorbers. We
find spectral variability in the $z = 0.886$ face-on spiral galaxy towards
PKSB1830$-$211, from observations undertaken with the Westerbork Synthesis
Radio Telescope in 1997/1998 and ASKAP BETA in 2014/2015. The HI equivalent
width varies by a few per cent over approximately yearly time-scales. This
long-term spectral variability is correlated between the north-east and
south-west images of the core, and with the total flux density of the source,
implying that it is observationally coupled to intrinsic changes in the quasar.
The absence of any detectable variability in the ratio of HI associated with
the two core images is in stark contrast to the behaviour previously seen in
the molecular lines. We therefore infer that coherent opaque HI structures in
this galaxy are larger than the parsec-scale molecular clouds found at
mm-wavelengths.


title:
Spatio-temporal Dynamics of Intrinsic Networks in Functional Magnetic
  Imaging Data Using Recurrent Neural Networks

abstract:
  We introduce a novel recurrent neural network (RNN) approach to account for
temporal dynamics and dependencies in brain networks observed via functional
magnetic resonance imaging (fMRI). Our approach directly parameterizes temporal
dynamics through recurrent connections, which can be used to formulate blind
source separation with a conditional (rather than marginal) independence
assumption, which we call RNN-ICA. This formulation enables us to visualize the
temporal dynamics of both first order (activity) and second order (directed
connectivity) information in brain networks that are widely studied in a static
sense, but not well-characterized dynamically. RNN-ICA predicts dynamics
directly from the recurrent states of the RNN in both task and resting state
fMRI. Our results show both task-related and group-differentiating directed
connectivity.


title: Spacetime completeness of non-singular black holes in conformal gravity

abstract:
  We explicitly prove that the Weyl conformal symmetry solves the black hole
singularity problem, otherwise unavoidable in a generally covariant local or
non-local gravitational theory. Moreover, we yield explicit examples of local
and non-local theories enjoying Weyl and diffeomorphism symmetry (in short
co-covariant theories). Following the seminal paper by Narlikar and Kembhavi,
we provide an explicit construction of singularity-free spherically symmetric
and axi-symmetric exact solutions for black hole spacetimes conformally
equivalent to the Schwarzschild or the Kerr spacetime. We first check the
absence of divergences in the Kretschmann invariant for the rescaled metrics.
Afterwords, we show that the new types of black holes are geodesically complete
and linked by a Newman-Janis transformation just as in standard general
relativity (based on Einstein-Hilbert action). Furthermore, we argue that no
massive or massless particles can reach the former Schwarzschild singularity or
touch the former Kerr ring singularity in a finite amount of their proper time
or of their affine parameter. Finally, we discuss the Raychaudhuri equation in
a co-covariant theory and we show that the expansion parameter for congruences
of both types of geodesics (for massless and massive particles) never reaches
minus infinity. Actually, the null geodesics become parallel at the $r=0$ point
in the Schwarzschild spacetime (the origin) and the focusing of geodesics is
avoided. The arguments of regularity of curvature invariants, geodesic
completeness, and finiteness of geodesics' expansion parameter ensure us that
we are dealing with singularity-free and geodesically-complete black hole
spacetimes.

categories: gr-qc astro-ph.CO hep-th math-ph math.MP


title: Tensor Decomposition via Variational Auto-Encoder

abstract:
  Tensor decomposition is an important technique for capturing the high-order
interactions among multiway data. Multi-linear tensor composition methods, such
as the Tucker decomposition and the CANDECOMP/PARAFAC (CP), assume that the
complex interactions among objects are multi-linear, and are thus insufficient
to represent nonlinear relationships in data. Another assumption of these
methods is that a predefined rank should be known. However, the rank of tensors
is hard to estimate, especially for cases with missing values. To address these
issues, we design a Bayesian generative model for tensor decomposition.
Different from the traditional Bayesian methods, the high-order interactions of
tensor entries are modeled with variational auto-encoder. The proposed model
takes advantages of Neural Networks and nonparametric Bayesian models, by
replacing the multi-linear product in traditional Bayesian tensor decomposition
with a complex nonlinear function (via Neural Networks) whose parameters can be
learned from data. Experimental results on synthetic data and real-world
chemometrics tensor data have demonstrated that our new model can achieve
significantly higher prediction performance than the state-of-the-art tensor
decomposition approaches.


title:
Bio-inspired seismic metamaterials: Time domain simulations in
  transformed crystals

abstract:
  We introduce the concept of transformation crystallography which consists of
the application of geometric transforms to periodic structures. We consider
motifs with three-fold, four-fold and six-fold symmetries according to the
crystallographic restriction theorem. Furthermore, we define motifs with
five-fold symmetry such as quasi-crystals generated by a cut-and-projection
method. We analyze elastic wave propagation in the transformed crystals and
(Penrose-type) quasi-crystals with the finite difference time domain freeware
SimSonic. We consider geometric transforms underpinning the design of seismic
cloaks with square, circular, elliptical and peanut shapes in the context of
triangular, square and honeycomb crystals. Interestingly, the use of morphing
techniques leads to the design of cloaks with interpolated geometries
reminiscent of Victor Vasarely's artwork. Employing the case of transformed
graphene-like (honeycomb) structures allows one to draw useful analogies
between large-scale seismic metamaterials such as soils structured with columns
of concrete or grout with soil and nanoscale biochemical metamaterials. We
further point out similarities between cloaks for elastodynamic and
hydrodynamic waves and cloaks for diffusion (heat or mass) diffusion processes,
notably with respect to invisibility and protection. Experimental data
extracted from field test analysis of soil structured with boreholes
demonstrates the application of bio-inspired seismic metamaterials. We conclude
that these novel materials hold strong applications in biophysics and
geophysics.


title: Incentive-Compatible Elicitation of Quantiles

abstract:
  Incorporation of expert information in inference or decision settings is
often important, especially in cases where data are unavailable, costly or
unreliable. One approach is to elicit prior quantiles from an expert and then
to fit these to a statistical distribution and proceed according to Bayes rule.
Quantiles are often thought to be easier to elicit than moments. An
incentive-compatible elicitation method using an external randomization is
available. Such a mechanism will encourage the expert to exert the care
necessary to report accurate information. A second application might be called
posterior elicitation. Here an analysis has been done and the results must be
reported to a decision maker. For a variety of reasons (possibly including the
reward system in the corporate hierarchy) the modeler might need the right
incentive system to report results accurately. Again, eliciting posterior
quantiles can be done with an incentive compatible mechanism.


title: QoE-based MAC Layer Optimization for Video Teleconferencing over WiFi

abstract:
  In IEEE 802.11, the retry limit is set the same value for all packets. In
this paper, we dynamically classify video teleconferencing packets based on the
type of the video frame that a packet carries and the packet loss events that
have happened in the network, and assign them different retry limits. We
consider the IPPP video encoding structure with instantaneous decoder refresh
(IDR) frame insertion based on packet loss feedback. The loss of a single frame
causes error propagation for a period of time equal to the packet loss feedback
delay. To optimize the video quality, we propose a method to concentrate the
packet losses to small segments of the entire video sequence, and study the
performance by an analytic model. Our proposed method is implemented only on
the stations interested in enhanced video quality, and is compatible with
unmodified IEEE 802.11 stations and access points in terms of performance.
Simulation results show that the performance gain can be significant compared
to the IEEE 802.11 standard without negatively affecting cross traffic.


title:
Radial equilibrium of relativistic particle bunches in plasma wakefield
  accelerators

abstract:
  Drive particle beams in linear or weakly nonlinear regimes of the plasma
wakefield accelerator quickly reach a radial equilibrium with the wakefield,
which is described in detail for the first time. The equilibrium beam state and
self-consistent wakefields are obtained by combining analytical relationships,
numerical integration, and first-principle simulations. In the equilibrium
state, the beam density is strongly peaked near the axis, the beam radius is
constant along the beam, and longitudinal variation of the focusing strength is
balanced by varying beam emittance. The transverse momentum distribution of
beam particles depends on the observation radius and is neither separable, nor
Gaussian.


title:
Derivations and 2-local derivations on matrix algebras over commutative
  algebras

abstract:
  We characterize derivations and 2-local derivations from $M_{n}(\mathcal{A})$
into $M_{n}(\mathcal{M})$, $n \ge 2$, where $\mathcal{A}$ is a unital algebra
over $\mathbb{C}$ and $\mathcal{M}$ is a unital $\mathcal{A}$-bimodule. We show
that every derivation $D: M_{n}(\mathcal{A}) \to M_{n}(\mathcal{M})$, $n \ge
2,$ is the sum of an inner derivation and a derivation induced by a derivation
from $\mathcal{A}$ to $\mathcal{M}$. We say that $\mathcal{A}$ commutes with
$\mathcal{M}$ if $am=ma$ for every $a\in\mathcal{A}$ and $m\in\mathcal{M}$. If
$\mathcal{A}$ commutes with $\mathcal{M}$ we prove that every inner 2-local
derivation $D: M_{n}(\mathcal{A}) \to M_{n}(\mathcal{M})$, $n \ge 2$, is an
inner derivation. In addition, if $\mathcal{A}$ is commutative and commutes
with $\mathcal{M}$, then every 2-local derivation $D: M_{n}(\mathcal{A}) \to
M_{n}(\mathcal{M})$, $n \ge 2$, is a derivation.


title:
A Decision Support System for Inbound Marketers: An Empirical Use of
  Latent Dirichlet Allocation Topic Model to Guide Infographic Designers

abstract:
  Infographic is a type of information presentation that inbound marketers use.
I suggest a method that can allow the infographic designers to benchmark their
design against the previous viral infographics to measure whether a given
design decision can help or hurt the probability of the design becoming viral.


title:
Extracting Actionability from Machine Learning Models by Sub-optimal
  Deterministic Planning

abstract:
  A main focus of machine learning research has been improving the
generalization accuracy and efficiency of prediction models. Many models such
as SVM, random forest, and deep neural nets have been proposed and achieved
great success. However, what emerges as missing in many applications is
actionability, i.e., the ability to turn prediction results into actions. For
example, in applications such as customer relationship management, clinical
prediction, and advertisement, the users need not only accurate prediction, but
also actionable instructions which can transfer an input to a desirable goal
(e.g., higher profit repays, lower morbidity rates, higher ads hit rates).
Existing effort in deriving such actionable knowledge is few and limited to
simple action models which restricted to only change one attribute for each
action. The dilemma is that in many real applications those action models are
often more complex and harder to extract an optimal solution.
  In this paper, we propose a novel approach that achieves actionability by
combining learning with planning, two core areas of AI. In particular, we
propose a framework to extract actionable knowledge from random forest, one of
the most widely used and best off-the-shelf classifiers. We formulate the
actionability problem to a sub-optimal action planning (SOAP) problem, which is
to find a plan to alter certain features of a given input so that the random
forest would yield a desirable output, while minimizing the total costs of
actions. Technically, the SOAP problem is formulated in the SAS+ planning
formalism, and solved using a Max-SAT based approach. Our experimental results
demonstrate the effectiveness and efficiency of the proposed approach on a
personal credit dataset and other benchmarks. Our work represents a new
application of automated planning on an emerging and challenging machine
learning paradigm.


title:
Indirect Methods to Control Population Distribution in a Large Spin
  System

abstract:
  We demonstrate how a large spin system ($S=7/2$) with the ground and the
first excited state separated by a seven photon transition exhibit non
equilibrium thermodynamic properties and how the population distribution may be
manipulated using coupling between energy levels. The first method involves
non-adiabatic passage through an avoided level crossing controlled with an
external DC magnetic field and the resulting Landau Zener transition. The
second method is based on external cavity pumping to a higher energy state
hybridised with another state that is two single photon transitions away from
the ground state. The results are confirmed experimentally with Gd$^{3+}$
impurity ion ensemble in a YVO$_{4}$ crystal cooled to 20 mK, which also acts
as a microwave photonic whispering gallery mode resonator. Extremely long life
times are observed due to large number of photons required for the transition
between the ground and the first excited states.


title:
The dimension of automorphism groups of algebraic varieties with
  pseudo-effective log canonical divisors

abstract:
  Let $(X,D)$ be a log smooth pair of dimension $n$, where $D$ is a reduced
effective divisor such that the log canonical divisor $K_X + D$ is
pseudo-effective. Let $G$ be a connected algebraic subgroup of
$\mathrm{Aut}(X,D)$. We show that $G$ is a semi-abelian variety of dimension
$\le \min\{n-\bar{\kappa}(V), n\}$ with $V := X\setminus D$. In the dimension
two, Shigeru Iitaka claimed in his 1979 Osaka J. Math. paper that $\dim G\le
\bar{q}(V)$ for a log smooth surface pair with $\bar{\kappa}(V) = 0$ and
$\bar{p}_g(V) = 1$. We (re)prove and generalize this classical result for all
surfaces with $\bar{\kappa}=0$ without assuming Iitaka's classification of
logarithmic Iitaka surfaces or logarithmic $K3$ surfaces.


title:
High pressure synthesis of a hexagonal close-packed phase of the
  high-entropy alloy CrMnFeCoNi

abstract:
  High-entropy alloys, near-equiatomic solid solutions of five or more
elements, represent a new strategy for the design of materials with properties
superior to those of conventional alloys. However, their phase space remains
constrained, with transition metal high-entropy alloys exhibiting only face- or
body-centered cubic structures. Here, we report the high-pressure synthesis of
a hexagonal close-packed phase of the prototypical high-entropy alloy
CrMnFeCoNi. This martensitic transformation begins at 14 GPa and is attributed
to suppression of the local magnetic moments, destabilizing the initial fcc
structure. Similar to fcc-to-hcp transformations in Al and the noble gases, the
transformation is sluggish, occurring over a range of >40 GPa. However, the
behaviour of CrMnFeCoNi is unique in that the hcp phase is retained following
decompression to ambient pressure, yielding metastable fcc-hcp mixtures. This
demonstrates a means of tuning the structures and properties of high-entropy
alloys in a manner not achievable by conventional processing techniques.


title: de Broglie-Proca and Bopp-Podolsky massive photon gases in cosmology

abstract:
  We investigate the influence of massive photons on the evolution of the
expanding universe. Two particular models for generalized electrodynamics are
considered, namely de Broglie-Proca and Bopp-Podolsky electrodynamics. We
obtain the equation of state (EOS) $P=P(\varepsilon)$ for each case using
dispersion relations derived from both theories. The EOS are inputted into the
Friedmann equations of a homogeneous and isotropic space-time to determine the
cosmic scale factor $a(t)$. It is shown that the photon non-null mass does not
significantly alter the result $a\propto t^{1/2}$ valid for a massless photon
gas; this is true either in de Broglie-Proca's case (where the photon mass $m$
is extremely small) or in Bopp-Podolsky theory (for which $m$ is extremely
large).


title:
Optical probing of mechanical loss of a Si_{3}N_{4} membrane below 100
  mK

abstract:
  We report on low mechanical loss in a high-stress silicon nitride
(Si_{3}N_{4}) membrane at temperatures below 100 mK. We isolate a membrane via
a phononic shield formed within a supporting silicon frame, and measure the
mechanical quality factor of a number of high-tension membrane modes as we vary
our dilution refrigerator base temperature between 35 mK and 5 K. At the lowest
temperatures, we obtain a maximum quality factor (Q) of 2.3\times10^{8},
corresponding to a Q-frequency product (QFP) of 3.7\times10^{14} Hz. These
measurements complement the recent observation of improved quality factors of
Si_{3}N_{4} at ultralow temperatures via electrical detection. We also observe
a dependence of the quality factor on optical heating of the device. By
combining exceptional material properties, high tension, advanced isolation and
clamping techniques, high-stress mechanical objects are poised to explore a new
regime of exceptional quality factors. Such quality factors combined with an
optical probe at cryogenic temperatures will have a direct impact on resonators
as quantum objects, as well as force sensors at mK temperatures.


title: Stable laws for chaotic billiards with cusps at flat points

abstract:
  We consider billiards with a single cusp where the walls meeting at the
vertex of the cusp have zero one-sided curvature, thus forming a flat point at
the vertex. For H\"older continuous observables, we show that properly
normalized Birkoff sums, with respect to the billiard map, converge in law to a
totally skewed $\alpha$-stable law.


title:
Sensitivity analysis on chaotic dynamical system by Non-Intrusive Least
  Square Shadowing (NILSS)

abstract:
  This paper develops the non-intrusive formulation of the Least-squares
shadowing (LSS) method, for computing the sensitivity of long-time averaged
objectives in chaotic dynamical systems. This non-intrusive formulation
constrains the computation to only the unstable subspace, greatly reducing the
cost of LSS for many problems; moreover, it reparametrizes the LSS problem,
requiring only minor modifications to existing tangent solvers. NILSS is
demonstrated on a chaotic flow over a backward-facing step simulated with a
mesh of 12e3 cells.

categories: physics.comp-ph cs.CE cs.NA math.NA nlin.CD


title: Leading corrections to local approximations II (with turning points)

abstract:
  Quantum corrections to Thomas-Fermi (TF) theory are investigated for
noninteracting one-dimensional fermions with known uniform semiclassical
approximations to the density and kinetic energy. Their structure is analyzed,
and contributions from distinct phase space regions (classically-allowed versus
forbidden at the Fermi energy) are derived analytically. Universal formulas are
derived for both particle numbers and energy components in each region. For
example, in the semiclassical limit, exactly 1/(6\pi3^{1/2}) of a particle
leaks into the evanescent region beyond a turning point. The correct
normalization of semiclassical densities is proven analytically in the
semiclassical limit. Energies and densities are tested numerically in a variety
of one-dimensional potentials, especially in the limit where TF theory becomes
exact. The subtle relation between the pointwise accuracy of the semiclassical
approximation and integrated expectation values is explored. The limitations of
the semiclassical formulas are also investigated when the potential varies too
rapidly. The approximations are shown to work for multiple wells, except right
at the mid-phase point of the evanescent regions. The implications for density
functional approximations are discussed.


title:
Pattern formation in desiccated sessile colloidal droplets with salt
  admixture: Short review

abstract:
  This short review is devoted to the simple process of drying a
multi-component droplet consisting of a complex fluid containing a salt. These
processes provide a fascinating subject for study. The explanation of the rich
variety of patterns formed is not only an academic challenge, but a problem of
practical importance, as applications are growing in medical diagnosis and
improvement of coating/printing technology. The fundamental scientific problem
is the study of the mechanism of micro- and nanoparticle self-organization in
open systems. The specific fundamental problem to be solved, related to this
system is - the investigation of the mass transfer processes, the formation and
evolution of phase fronts and the identification of mechanisms of pattern
formation. The drops of liquid containing dissolved substances and suspended
particles are assumed to be drying on a horizontal solid substrate. The
chemical composition and macroscopic properties of the complex fluid, the
concentration and nature of the salt, the surface energy of the substrate and
the interaction between the fluid and substrate which determines the wetting,
all affect the final morphology of the dried film.


title: Wakefields studies for the SXFEL user facility

abstract:
  Besides the original seeded undulator line, in the Soft X-ray free-electron
laser (SXFEL) user facility at Shanghai, a second undulator line based on
self-amplified spontaneous emission is proposed to achieve 2 nm laser pulse
with extremely high brightness. In this paper, the beam energy deviation
induced by the undulator wakefields is numerically obtained, and it is verified
to have a good agreement between 3D and 2D simulation results. The beam energy
loss along the undulator degrades the expected FEL output performance. Impact
of wakefields on pulse energy, radiation power and spectrum is discussed, as
well as the benefits of compensation obtained with a taper in the undulator
field. And using the planned SXFEL diagnostic, a longitudinal wakefields
measurement experiment is proposed and simulated.


title: Mean likelihood estimators

abstract:
  The use of {\it Mathematica} in deriving mean likelihood estimators is
discussed. Comparisons between the maximum likelihood estimator, the mean
likelihood estimator and the Bayes estimate based on a Jeffrey's noninformative
prior using the criteria mean-square error and Pitman measure of closeness.
Based on these criteria we find that for the first-order moving-average time
series model, the mean likelihood estimator outperforms the maximum likelihood
estimator and the Bayes estimator with a Jeffrey's noninformative prior.
  {\it Mathematica} was used for symbolic and numeric computations as well as
for the graphical display of results. A {\it Mathematica} notebook is available
which provides supplementary derivations and code from
http://www.stats.uwo.ca/mcleod/epubs/mele The interested reader can easily
reproduce or extend any of the results in this paper using this supplement.


title:
Pricing Perpetual Put Options by the Black-Scholes Equation with a
  Nonlinear Volatility Function

abstract:
  We investigate qualitative and quantitative behavior of a solution of the
mathematical model for pricing American style of perpetual put options. We
assume the option price is a solution to the stationary generalized
Black-Scholes equation in which the volatility function may depend on the
second derivative of the option price itself. We prove existence and uniqueness
of a solution to the free boundary problem. We derive a single implicit
equation for the free boundary position and the closed form formula for the
option price. It is a generalization of the well-known explicit closed form
solution derived by Merton for the case of a constant volatility. We also
present results of numerical computations of the free boundary position, option
price and their dependence on model parameters.


title:
All or nothing: toward a promise problem dichotomy for constraint
  problems

abstract:
  A finite constraint language $\mathscr{R}$ is a finite set of relations over
some finite domain $A$. We show that intractability of the constraint
satisfaction problem $\operatorname{CSP}(\mathscr{R})$ can, in all known cases,
be replaced by an infinite hierarchy of intractable promise problems of
increasingly disparate promise conditions: where instances are guaranteed to
either have no solutions at all, or to be $k$-robustly satisfiable (for any
fixed $k$), meaning that every "reasonable" partial instantiation on~$k$
variables extends to a solution. For example, subject to the assumption
$\texttt{P}\neq \texttt{NP}$, then for any~$k$, we show that there is no
polynomial time algorithm that can distinguish non-$3$-colourable graphs, from
those for which any reasonable $3$-colouring of any $k$ of the vertices can
extend to a full $3$-colouring. Our main result shows that an analogous
statement holds for all known intractable constraint problems over fixed finite
constraint languages.


title: Spin caloritronic nano-oscillator

abstract:
  Energy loss due to ohmic heating is a major bottleneck limiting down-scaling
and speed of nano-electronic devices, and harvesting ohmic heat for signal
processing is a major challenge in modern electronics. Here we demonstrate that
thermal gradients arising from ohmic heating can be utilized for excitation of
coherent auto-oscillations of magnetization and for generation of tunable
microwave signals. The heat-driven dynamics is observed in
$\mathrm{Y_{3}Fe_{5}O_{12}/Pt}$ bilayer nanowires where ohmic heating of the Pt
layer results in injection of pure spin current into the
$\mathrm{Y_{3}Fe_{5}O_{12}}$ layer. This leads to excitation of
auto-oscillations of the $\mathrm{Y_{3}Fe_{5}O_{12}}$ magnetization and
generation of coherent microwave radiation. Our work paves the way towards spin
caloritronic devices for microwave and magnonic applications.


title:
Accurate high-harmonic spectra from time-dependent two-particle reduced
  density matrix theory

abstract:
  The accurate description of the non-linear response of many-electron systems
to strong-laser fields remains a major challenge. Methods that bypass the
unfavorable exponential scaling with particle number are required to address
larger systems. In this paper we present a fully three-dimensional
implementation of the time-dependent two-particle reduced density matrix
(TD-2RDM) method for many-electron atoms. We benchmark this approach by a
comparison with multi-configurational time-dependent Hartree-Fock (MCTDHF)
results for the harmonic spectra of beryllium and neon. We show that the
TD-2RDM is very well-suited to describe the non-linear atomic response and to
reveal the influence of electron-correlation effects.


title: Designing Sparse Reliable Pose-Graph SLAM: A Graph-Theoretic Approach

abstract:
  In this paper, we aim to design sparse D-optimal (determinantoptimal)
pose-graph SLAM problems through the synthesis of sparse graphs with the
maximum weighted number of spanning trees. Characterizing graphs with the
maximum number of spanning trees is an open problem in general. To tackle this
problem, several new theoretical results are established in this paper,
including the monotone log-submodularity of the weighted number of spanning
trees. By exploiting these structures, we design a complementary pair of
near-optimal efficient approximation algorithms with provable guarantees. Our
theoretical results are validated using random graphs and a publicly available
pose-graph SLAM dataset.


title:
Maximizing Investment Value of Small-Scale PV in a Smart Grid
  Environment

abstract:
  Determining the optimal size and orientation of small-scale residential based
PV arrays will become increasingly complex in the future smart grid environment
with the introduction of smart meters and dynamic tariffs. However consumers
can leverage the availability of smart meter data to conduct a more detailed
exploration of PV investment options for their particular circumstances. In
this paper, an optimization method for PV orientation and sizing is proposed
whereby maximizing the PV investment value is set as the defining objective.
Solar insolation and PV array models are described to form the basis of the PV
array optimization strategy. A constrained particle swarm optimization
algorithm is selected due to its strong performance in non-linear applications.
The optimization algorithm is applied to real-world metered data to quantify
the possible investment value of a PV installation under different energy
retailers and tariff structures. The arrangement with the highest value is
determined to enable prospective small-scale PV investors to select the most
cost-effective system.


title:
Role of force-constant difference in phonon scattering by
  nano-precipitates in PbTe

abstract:
  We study the effect of nanoscale precipitates on lattice thermal conduction
in thermoelectric PbTe using a combination of ab-initio phonon calculations and
molecular dynamics. We take into account the effects of mass difference and
change in force constants, and find an enhanced influence of the latter with
increased precipitate concentration. As a consequence, our inclusion of the
change in force constants in the calculation affords a smaller predicted
optimal nano-precipitate size that minimizes the thermal conductivity. These
results suggest that the phonon scattering by nanoprecipitates in
thermoelectric composites could be stronger than previously thought.


title:
Ultra-Light Axion Dark Matter and its impacts on dark halo structure in
  $N$-body simulation

abstract:
  The Ultra-Light Axion (ULA) is a dark matter candidate with mass
$\mathcal{O}(10^{-22})$eV and de Broglie wavelength of order kpc. Such an
axion, also called the Fuzzy Dark Matter (FDM), thermalizes via the
gravitational force and forms a Bose-Einstein condensate. Recent studies
suggested that the quantum pressure from the FDM can significantly affect the
structure formation in small scales, thus alleviating the so-called
"small-scale crisis". In this paper, we develop a new technique to discretize
the quantum pressure and illustrate the interactions among FDM particles in the
$N$-body simulation, which accurately simulates the formation of the
dark-matter halo and its inner structure in the region outside the softening
length. In a self-gravitationally-bound virialized halo, we find a constant
density, solitonic core, which is consistent with the theoretical prediction.
The existence of the solitonic core reveals the non-linear effect of quantum
pressure and impacts the structure formation in the FDM model.


title: On Carlotto-Schoen-type scalar-curvature gluings

abstract:
  We carry out a Carlotto-Schoen-type gluing with interpolating scalar
curvature on cone-like sets, or deformations thereof, in the category of smooth
Riemannian asymptotically Euclidean metrics.


title:
Atomistic mechanisms governing structural stability change of zinc
  antimony thermoelectrics

abstract:
  The structural stability of thermoelectric materials is a subject of growing
importance for their energy harvesting applications. Here, we study the
microscopic mechanisms governing the structural stability change of zinc
antimony at its working temperature, using molecular dynamics combined with
experimental measurements of the electrical and thermal conductivity. Our
results show that the temperature-dependence of the thermal and electrical
transport coefficients is strongly correlated with a structural transition.
This is found to be associated with a relaxation process, in which a group of
Zn atoms migrates between interstitial sites. This atom migration gradually
leads to a stabilizing structural transition of the entire crystal framework,
and then results in a more stable crystal structure of $\beta-$ Zn4Sb3 at high
temperature.


title:
High yield synthesis and liquid exfoliation of two-dimensional belt like
  hafnium disulphide

abstract:
  Producing monolayers and few-layers in high yield with environment-stability
is still a challenge in hafnium disulphide (HfS2), which is a layered
two-dimensional material of group-IV transition metal dichalcogenides, to
reveal its unlocked electronic and optoelectronic applications. For the first
time, to the best of our knowledge, we demonstrate a simple and cost-effective
method to grow layered belt-like nano-crystals of HfS2 with surprisingly large
interlayer spacing followed by its chemical exfoliation. Various microscopic
and spectroscopic techniques reveal these as-grown crystals exfoliate into
single or few layers in some minutes using solvent assisted ultrasonification
method in N-Cyclohexyl-2-pyrrolidone. The exfoliated nanosheets of HfS2 exhibit
an indirect bandgap of 1.3 eV with high stability against ambient degradation.
Further, we demonstrate that these nanosheets holds potential for electronic
applications by fabricating field-effect transistors based on few layered HfS2
exhibiting field-effect mobility of 0.95 cm2/V-s with a high current modulation
ratio (Ion/Ioff) of 10^4 in ambient. The method is scalable and has potential
significance for both academy and industry.


title: Cold gas stripping in satellite galaxies: from pairs to clusters

abstract:
  In this paper we investigate environment driven gas depletion in satellite
galaxies, taking full advantage of the atomic hydrogen (HI) spectral stacking
technique to quantify the gas content for the entire gas-poor to -rich regime.
We do so using a multi-wavelength sample of 10,600 satellite galaxies, selected
according to stellar mass (log M$_{\star}$/M$_{\odot}$ $\geq$ 9) and redshift
(0.02 $\leq$ z $\leq$ 0.05) from the Sloan Digital Sky Survey, with HI data
from the Arecibo Legacy Fast ALFA (ALFALFA) survey. Using key HI-to-stellar
mass scaling relations, we present evidence that the gas content of satellite
galaxies is, to a significant extent, dependent on the environment in which a
galaxy resides. For the first time, we demonstrate that systematic
environmental suppression of gas content at both fixed stellar mass and fixed
specific star formation rate (sSFR) in satellite galaxies begins in halo masses
typical of the group regime (log M$_{h}$/M$_{\odot}$ < 13.5), well before
galaxies reach the cluster environment. We also show that environment driven
gas depletion is more closely associated to halo mass than local density. Our
results are then compared with state-of-the-art semi-analytic models and
hydrodynamical simulations and discussed within this framework, showing that
more work is needed if models are to reproduce the observations. We conclude
that the observed decrease of gas content in the group and cluster environments
cannot be reproduced by starvation of the gas supply alone and invoke fast
acting processes such as ram-pressure stripping of cold gas to explain this.


title: Joint multifractal analysis based on wavelet leaders

abstract:
  Mutually interacting components form complex systems and the outputs of these
components are usually long-range cross-correlated. Using wavelet leaders, we
propose a method of characterizing the joint multifractal nature of these
long-range cross correlations, a method we call joint multifractal analysis
based on wavelet leaders (MF-X-WL). We test the validity of the MF-X-WL 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. Both experiments indicate
that MF-X-WL is capable to detect the cross correlations in synthetic data with
acceptable estimating errors. We also apply the MF-X-WL method to the pairs of
series from financial markets (returns and volatilities) and online worlds
(online numbers of different genders and different societies) and find an
intriguing joint multifractal behavior.


title: Low Rank Approximation with Entrywise $\ell_1$-Norm Error

abstract:
  We study the $\ell_1$-low rank approximation problem, where for a given $n
\times d$ matrix $A$ and approximation factor $\alpha \geq 1$, the goal is to
output a rank-$k$ matrix $\widehat{A}$ for which
  $$\|A-\widehat{A}\|_1 \leq \alpha \cdot \min_{\textrm{rank-}k\textrm{
matrices}~A'}\|A-A'\|_1,$$ where for an $n \times d$ matrix $C$, we let
$\|C\|_1 = \sum_{i=1}^n \sum_{j=1}^d |C_{i,j}|$. This error measure is known to
be more robust than the Frobenius norm in the presence of outliers and is
indicated in models where Gaussian assumptions on the noise may not apply. The
problem was shown to be NP-hard by Gillis and Vavasis and a number of
heuristics have been proposed. It was asked in multiple places if there are any
approximation algorithms.
  We give the first provable approximation algorithms for $\ell_1$-low rank
approximation, showing that it is possible to achieve approximation factor
$\alpha = (\log d) \cdot \mathrm{poly}(k)$ in $\mathrm{nnz}(A) + (n+d)
\mathrm{poly}(k)$ time, where $\mathrm{nnz}(A)$ denotes the number of non-zero
entries of $A$. If $k$ is constant, we further improve the approximation ratio
to $O(1)$ with a $\mathrm{poly}(nd)$-time algorithm. Under the Exponential Time
Hypothesis, we show there is no $\mathrm{poly}(nd)$-time algorithm achieving a
$(1+\frac{1}{\log^{1+\gamma}(nd)})$-approximation, for $\gamma > 0$ an
arbitrarily small constant, even when $k = 1$.
  We give a number of additional results for $\ell_1$-low rank approximation:
nearly tight upper and lower bounds for column subset selection, CUR
decompositions, extensions to low rank approximation with respect to
$\ell_p$-norms for $1 \leq p < 2$ and earthmover distance, low-communication
distributed protocols and low-memory streaming algorithms, algorithms with
limited randomness, and bicriteria algorithms. We also give a preliminary
empirical evaluation.


title:
Power of an optical Maxwell's demon in the presence of photon-number
  correlations

abstract:
  We study how correlations affect the performance of the simulator of a
Maxwell's demon demonstrated in a recent optical experiment [Vidrighin et al.,
Phys. Rev. Lett. 116, 050401 (2016)]. The power of the demon is found to be
enhanced or hindered, depending on the nature of the correlation, in close
analogy to the situation faced by a thermal demon.


title:
Pauli equations and non-commutative position operators in 2D Dirac-like
  semiconductors in view of second quantization

abstract:
  The Pauli equations describing electron (hole) dynamics in 2D Dirac-like
intrinsic semiconductors in external (impurity) scalar potential and for
inhomogeneous lattice distortions are obtained within second quantization
approach. We show that the modifying external perturbation terms in formulated
no-pair equations are in general non-local and demonstrates singular behavior
in gapless situation where they do not depend on semiconductor parameters. It
is shown that lattice distortion perturbation can cause confinement of both
electrons and holes in the same spatial region. The proposed approach is
verified by comparison with well-established results in low energy limit. The
consideration of position operator in second quantization approach allows
elucidating the physical meaning of spin-orbit-like and Darwin-like terms.


title: Optimizing phonon scattering by nanoprecipitates in lead chalcogenides

abstract:
  We calculate the thermal conductivity of PbTe and PbS with seven different
types of nanoprecipitates using an ab-initio-based Boltzmann transport
approach. We find that precipitates with realistic size distributions can
reduce the thermal conductivity well below the predictions of theoretical
models assuming a single precipitate size.We explore the question of how to
tune this distribution to reduce the thermal conductivity even further. The
predicted minimum value is strongly correlated with the phonon spectrum of the
host material and with the mass density difference between the host and the
inclusions.


title:
A Hybrid Algorithm of Fast Invariant Imbedding and Doubling-Adding
  Methods for Efficient Multiple Scattering Calculations

abstract:
  An efficient hybrid numerical method for multiple scattering calculations is
proposed. We use the well established doubling--adding method to find the
reflection function of the lowermost homogeneous slab comprising the atmosphere
of our interest. This reflection function provides the initial value for the
fast invariant imbedding method of Sato et al., (1977), with which layers are
added until the final reflection function of the entire atmosphere is obtained.
The execution speed of this hybrid method is no slower than one half of that of
the doubling-adding method, probably the fastest algorithm available, even in
the most unsuitable cases for the fast invariant imbedding method. The
efficiency of the proposed method increases rapidly with the number of
atmospheric slabs and the optical thickness of each slab. For some cases, its
execution speed is approximately four times faster than the doubling--adding
method. This work has been published in NAIS Journal (ISSN 1882-9392) Vol. 7,
5-16 (2012).


title:
Mechanisms governing phonon scattering by topological defects in
  graphene nanoribbons

abstract:
  Understanding phonon scattering by topological defects in graphene is of
particular interest for thermal management in graphene-based devices. We
present a study that quantifies the roles of the different mechanisms governing
defect phonon scattering by comparing the effects of ten different defect
structures using molecular dynamics. Our results show that phonon scattering is
mainly influenced by mass density difference, with general trends governed by
the defect formation energy and typical softening behaviors in the phonon
density of state. The phonon scattering cross-section is found to be far larger
than that geometrically occupied by the defects. We also show that the lattice
thermal conductivity can be reduced by a factor of up to ~30 in the presence of
the grain boundaries formed by these defects.


title: An Improved Method to Measure the Cosmic Curvature

abstract:
  In this paper, we propose an improved model-independent method to constrain
the cosmic curvature by combining the most recent Hubble parameter $H(z)$ and
supernovae Ia (SNe Ia) data. Based on the $H(z)$ data, we first use the
model-independent smoothing technique, Gaussian processes, to construct
distance modulus $\mu_{H}(z)$, which is susceptible to the cosmic curvature
parameter $\Omega_{k}$. In contrary to previous studies, the light-curve
fitting parameters, which account for distance estimation of SN
($\mu_{SN}(z)$), are set free to investigate whether $\Omega_{k}$ has a
dependence on them. By comparing $\mu_{H}(z)$ to $\mu_{SN}(z)$, we put limits
on $\Omega_{k}$. Our results confirm that $\Omega_{k}$ is independent of the SN
light-curve parameters. Moreover, we show that the measured $\Omega_{k}$ is in
good agreement with zero cosmic curvature, implying that there is no
significant deviation from a flat Universe at the current observational data
level. We also test the influence of different $H(z)$ samples and different
Hubble constant $H_{0}$ values, finding that different $H(z)$ samples do not
present significant impact on the constraints. However, different $H_{0}$
priors can affect the constraints of $\Omega_{k}$ in some degree. The prior of
$H_{0}=73.24\pm1.74$ km $\rm s^{-1}$ $\rm Mpc^{-1}$ gives a value of
$\Omega_{k}$ a little bit above $1\sigma$ confidence level away from 0, but
$H_{0}=69.6\pm0.7$ km $\rm s^{-1}$ $\rm Mpc^{-1}$ gives it below $1\sigma$.


title:
Two-dimensionalization of the flow driven by a slowly rotating impeller
  in a rapidly rotating fluid

abstract:
  We characterize the two-dimensionalization process in the turbulent flow
produced by an impeller rotating at a rate $\omega$ in a fluid rotating at a
rate $\Omega$ around the same axis for Rossby number $Ro=\omega/\Omega$ down to
$10^{-2}$. The flow can be described as the superposition of a large-scale
vertically invariant global rotation and small-scale shear layers detached from
the impeller blades. As $Ro$ decreases, the large-scale flow is subjected to
azimuthal modulations. In this regime, the shear layers can be described in
terms of wakes of inertial waves traveling with the blades, originating from
the velocity difference between the non-axisymmetric large-scale flow and the
blade rotation. The wakes are well defined and stable at low Rossby number, but
they become disordered at $Ro$ of order of 1. This experiment provides insight
into the route towards pure two-dimensionalization induced by a background
rotation for flows driven by a non-axisymmetric rotating forcing.


title:
Slope of the lateral density function of extensive air showers around
  the knee region as an indicator of shower age

abstract:
  Analyzing simulated extensive air shower (EAS) events generated with the
Monte Carlo code CORSIKA, this paper critically studies the characteristics of
lateral distribution of electrons in EAS around the knee energy region of the
energy spectrum of primary cosmic rays. The study takes into account the issue
of lateral shower age parameter as indicator of the stage of development of
showers in the atmosphere. The correlation of lateral shower age parameter with
other EAS observables is examined, using simulated data in the context of its
possible use in a multi-parameter study of EAS, with a view to obtaining
information about the nature of the shower initiating primaries at sea level
EAS experiments. It is shown that the observed slope of the lateral density
function in the 3-dimensional plot at least for the KASCADE data supports the
idea of a transition from light to heavy mass composition around the knee.


title: Chemical-potential-based Lattice Boltzmann Method for Nonideal Fluids

abstract:
  Chemical potential is an effective way to drive phase transition or express
wettability. In this letter, we present a chemical-potential-based lattice
Boltzmann model to simulate multiphase flows. The nonideal force is directly
evaluated by a chemical potential. The model theoretically satisfies
thermodynamics and Galilean invariance. The computational efficiency is
improved owing to avoiding the calculation of pressure tensor. We have derived
several chemical potentials of the popular equations of state from the
free-energy density function. An effective chemical-potential boundary
condition is implemented to investigate the wettability of a solid surface.
Remarkably, the numerical results show that the contact angle can be linearly
tuned by the surface chemical potential.


title:
Interaction-induced metallic state in graphene on hexagonal boron
  nitride

abstract:
  The Coulomb interaction is widely known to enhance the effective mass of
interacting particles and therefore tends to favor a localized state at
commensurate filling. Here, we will show that, in contrast to this consensus,
in a van der Waals heterostructure consisting of graphene and hexagon boron
nitride (h-BN), the onsite Coulomb repulsion will at first destroy the
localized state. This is due to the fact that the onsite Coulomb repulsion
tends to suppress the asymmetry between neighboring carbons induced by h-BN
substrate. We corroborate this surprising phenomenon by solving a tight-binding
model with onsite Coulomb repulsion treated within coherent potential
approximation, where hopping parameters are derived from density functional
theory calculations based on the graphene/h-BN heterostructure. Our results
indicate that both gapless and gapped states observed experimentally in
graphene/h-BN heterostructures can be understood after a realistic value of the
onsite Coulomb repulsion as well as different interlayer distances are taken
into account. Finally, we propose ways to enhance the gapped state which is
essential for potential application of graphene to next-generation electronics.
Furthermore, we argue that band gap suppressed by many-body effect should
happen in other van der Waals heterostructures.