title: Polynomial Time Computable Triangular Arrays For Almost Sure Convergence

abstract:
  For 0 < x < 1, take the binary expansion with infinitely many 0's, replace
each 0 with -1, this gives the polarized binary expansion of x. Let R_i(x) be
the ith "polarized bit" and let S_n(x) be the sum of the first n R_i(x). {S_n}
is the Z-valued random walk on (0,1). Normalize, by dividing each S_n by the
square root of n: the resulting sequence converges weakly to the standard
normal distribution on (0,1). The quantiles of S_n are random variables on
(0,1), denoted S*_n, which are equal in distribution to the S_n, Skorokhod
showed that the sequence of normalized quantiles converges almost surely to the
standard normal distribution on (0,1).
  For n > 2, S*_n cannot be represented as the sum of the first n terms of a
fixed sequence, R*_i, of random variables with the properties of the R_i. We
introduce a method of constructing, for each n, an i.i.d family, R*_(n,1), ...
R*_(n,n) which sums to S*_n, pointwise, as a function, not just in
distribution. Each R*_(n,i) is a mean 0, variance 1 Rademacher random variable
depending only on the first n bits. For each n, we get a bijection between the
set of all such i.i.d. families, R*_(n,1), ... R*_(n,n), and the set of all
admissible permutations of {0, ..., (2^n)-1}.
  Varying n, any doubly indexed such family, gives a triangular array
representation of the sequence {S*_n} which is strong (because for each n, S*_n
is the pointwise sum of the R*_(n,i)). Such representations are classified by
sequences of admissible permutations. We show that the complexity of any
sequence of admissible permutations is bounded below by that of 2^n. We
explicitly construct three such polynomial time computable sequences whose
complexity is bounded above by that of the function SBC (sum of binomial
coefficients). We also initiate the study of some additional fine properties of
admissible permutations.


title: Locally piecewise affine functions and their order structure

abstract:
  Piecewise affine functions on subsets of $\mathbb R^m$ were studied in
\cite{Ovchinnikov:02,Aliprantis:06a,Aliprantis:07a,Aliprantis:07}. In this
paper we study a more general concept of a locally piecewise affine function.
We characterize locally piecewise affine functions in terms of components and
regions. We prove that a positive function is locally piecewise affine iff it
is the supremum of a locally finite sequence of piecewise affine functions. We
prove that locally piecewise affine functions are uniformly dense in $C(\mathbb
R^m)$, while piecewise affine functions are sequentially order dense in
$C(\mathbb R^m)$.
  This paper is partially based on \cite{Adeeb:14}.


title:
Inflationary quasiparticle creation and thermalization dynamics in
  coupled Bose-Einstein condensates

abstract:
  A Bose gas in a double-well potential, exhibiting a true Bose-Einstein
condensate (BEC) amplitude and initially performing Josephson oscillations, is
a prototype of an isolated, non-equilibrium many-body system. We investigate
the quasiparticle (QP) creation and thermalization dynamics of this system by
solving the time-dependent Keldysh-Bogoliubov equations. We find avalanche-like
QP creation due to a parametric resonance between BEC and QP oscillations,
followed by slow, exponential relaxation to a thermal state at an elevated
temperature, controlled by the initial excitation energy of the oscillating BEC
above its ground state. The crossover between the two regimes occurs because of
an effective decoupling of the QP and BEC oscillations. This dynamics is
analogous to elementary particle creation in models of the early universe. The
thermalization in our set-up occurs because the BEC acts as a grand canonical
reservoir for the quasiparticle system.

categories: cond-mat.quant-gas astro-ph.CO cond-mat.stat-mech quant-ph


title:
Coexistence of superconductivity and antiferromagnetism in
  Ca$_{0.74(1)}$La$_{0.26(1)}$(Fe$_{1-x}$Co$_{x}$)As$_{2}$ single crystals

abstract:
  We report the transport, thermodynamic, $\mu$SR and neutron study of the
Ca$_{0.74(1)}$La$_{0.26(1)}$(Fe$_{1-x}$Co$_{x}$)As$_{2}$ single crystals,
mapping out the temperature-doping level phase diagram. Upon Co substitution on
the Fe site, the structural/magnetic phase transitions in this 112 compound are
suppressed and superconductivity up to 20 K occurs. Our measurements of the
superconducting and magnetic volume fractions show that these two phases
coexist microscopically in the underdoped region, in contrast to the related
10-3-8 Ca$_{10}$(Pt$_{3}$As$_{8}$)((Fe$_{1-x}$Pt$_x$)$_{2}$As$_{2}$)$_{5}$
compound, where coexistence is absent. Supported by model calculations, we
discuss the differences in the phase diagrams of the 112 and 10-3-8 compounds
in terms of the FeAs interlayer coupling, whose strength is affected by the
character of the spacer layer, which is metallic in the 112 and insulating in
the 10-3-8.


title:
A Numerical Study of Long-Range Magnetic Impacts during Coronal Mass
  Ejections

abstract:
  With the global view and high-cadence observations from SDO/AIA and STEREO,
many spatially separated solar eruptive events appear to be coupled. However,
the mechanisms for "sympathetic" events are still largely unknown. In this
study, we investigate the impact of an erupting flux rope on surrounding solar
structures through large-scale magnetic coupling. We build a realistic
environment of the solar corona on 2011 February 15 using a global
magnetohydrodynamics (MHD) model and initiate coronal mass ejections (CMEs) in
active region (AR) 11158 by inserting Gibson-Low analytical flux ropes. We show
that a CME's impact on the surrounding structures depends not only on the
magnetic strength of these structures and their distance to the source region,
but also on the interaction between the CME with the large-scale magnetic
field. Within the CME expansion domain where the flux rope field directly
interacts with the solar structures, expansion-induced reconnection often
modifies the overlying field, thereby increasing the decay index. This effect
may provide a primary coupling mechanism underlying the sympathetic eruptions.
The magnitude of the impact is found to depend on the orientation of the
erupting flux rope, with the largest impacts occurring when the flux rope is
favorably oriented for reconnecting with the surrounding regions. Outside the
CME expansion domain, the influence of the CME is mainly through field line
compression or post-eruption relaxation. Based on our numerical experiments, we
discuss a way to quantify the eruption impact, which could be useful for
forecasting purposes.


title:
Dilations of semigroups on von Neumann algebras and noncommutative
  $\mathrm{L}^p$-spaces

abstract:
  We prove that any weak* continuous semigroup $(T_t)_{t \geq 0}$ of
factorizable Markov maps acting on a von Neumann algebra $M$ equipped with a
normal faithful state can be dilated by a group of Markov $*$-automorphisms
analogous to the case of a single factorizable Markov operator, which is an
optimal result. We also give a version of this result for strongly continuous
semigroups of operators acting on noncommutative $\mathrm{L}^p$-spaces and
examples of semigroups to which the results of this paper can be applied. Our
results implies the boundedness of the McIntosh's $\mathrm{H}^\infty$
functional calculus of the generators of these semigroups on the associated
noncommutative $\mathrm{L}^p$-spaces generalising some previous work from
Junge, Le Merdy and Xu. Finally, we also give concrete dilations for Poisson
semigroups which are even new in the case of $\mathbb{R}^n$.


title: Heat flux and information backflow in cold condensed matter systems

abstract:
  We examine non-Markovian effects in an open quantum system from the point of
view of information flow. To this end, we consider the spin-boson model with a
cold reservoir, accounting for the exact time-dependent correlations between
the system and the bath to study the exchange of information and heat. We use
an information theoretic measure of the relevant memory effects and demonstrate
that the information backflow from the reservoir to the system does not
necessarily correlate with the backflow of heat. We also examine the influence
of temperature and coupling strength on the loss and gain of information
between the system and the bath. Finally, we discuss how additional driving
changes the backflow of information, giving rise to potential applications in
reservoir engineering.


title: Half-levitons -- zero-energy excitations of a driven Fermi sea

abstract:
  A voltage pulse of a Lorentzian shape carrying a half of the flux quantum
excites out of a zero-temperature Fermi sea an electron in a mixed state, which
looks like a quasi-particle with an effectively fractional charge $e/2$. A
prominent feature of such an excitation is a narrow peak in the energy
distribution function laying exactly at the Fermi energy $ \mu$. Another
spectacular feature is that the distribution function has symmetric tails as
above as below $ \mu$, which results in a zero energy of an excitation. This
sounds improbable since at zero temperature all available states below $ \mu$
are fully occupied. The resolution is lying in the fact that such a voltage
pulse excites also electron-hole pairs which free some space below $ \mu$ and
thus allow a zero-energy quasi-particle to exist. I discuss also how to address
separately electron-hole pairs and a fractionally charged zero-energy
excitation in experiment.


title:
Turing learning: a metric-free approach to inferring behavior and its
  application to swarms

abstract:
  We propose Turing Learning, a novel system identification method for
inferring the behavior of natural or artificial systems. Turing Learning
simultaneously optimizes two populations of computer programs, one representing
models of the behavior of the system under investigation, and the other
representing classifiers. By observing the behavior of the system as well as
the behaviors produced by the models, two sets of data samples are obtained.
The classifiers are rewarded for discriminating between these two sets, that
is, for correctly categorizing data samples as either genuine or counterfeit.
Conversely, the models are rewarded for 'tricking' the classifiers into
categorizing their data samples as genuine. Unlike other methods for system
identification, Turing Learning does not require predefined metrics to quantify
the difference between the system and its models. We present two case studies
with swarms of simulated robots and prove that the underlying behaviors cannot
be inferred by a metric-based system identification method. By contrast, Turing
Learning infers the behaviors with high accuracy. It also produces a useful
by-product - the classifiers - that can be used to detect abnormal behavior in
the swarm. Moreover, we show that Turing Learning also successfully infers the
behavior of physical robot swarms. The results show that collective behaviors
can be directly inferred from motion trajectories of individuals in the swarm,
which may have significant implications for the study of animal collectives.
Furthermore, Turing Learning could prove useful whenever a behavior is not
easily characterizable using metrics, making it suitable for a wide range of
applications.


title: Almost Periodicity in Time of Solutions of the Toda Lattice

abstract:
  We study an initial value problem for the Toda lattice with almost periodic
initial data. We consider initial data for which the associated Jacobi operator
is absolutely continuous and has a spectrum satisfying a Craig-type condition,
and show the boundedness and almost periodicity in time and space of solutions.


title:
Evaluation and Ensembling of Methods for Reverse Engineering of Brain
  Connectivity from Imaging Data

abstract:
  Brain science is an evolving research area inviting great enthusiasm with its
potential for providing insights and thereby, preventing, and treating multiple
neuronal disorders affecting millions of patients. Discovery of relationships,
such as brain connectivity, is a major goal in basic, translational, and
clinical science. Algorithms for causal discovery are used in diverse fields
for tackling problems similar to the task of reconstruction of neuronal brain
connectivity. Our aim is to understand the strengths and limitations of these
methods, measure performance and its determinants, and provide insights to
enhance their performance and applicability. We performed extensive empirical
testing and benchmarking of reconstruction performance of several
state-of-the-art algorithms along with several ensemble techniques used to
combine them. Our experiments used a clear and broadly relevant gold standard
based on calcium fluorescence time series recordings of thousands of neurons
sampled from a previously validated realistic, neuronal model. Correlation,
entropy-based measures, Cross-Correlation for short time lags, and Generalized
Transfer Entropy had the best performances with area under ROC curve (AUC) in
the range of 0.7-0.8 even for smaller sample sizes of n = 100 to 1,000 and
converged quickly (at less than n = 1,000). Ensembles of best-performing
methods using random forests and neural networks generated AUC of ~0.9 with n =
10,000. Several important insights regarding parameter choice and sample size
were gained for guiding the experimental design of studies. Our data are also
supportive of the feasibility of reliably reconstructing complex neuronal
connectivity using existing techniques.


title: Ne X X-ray Emission due to Charge Exchange in M82

abstract:
  Recent X-ray observations of star-forming galaxies such as M82 have shown the
Ly beta/Ly alpha line ratio of Ne X to be in excess of predictions for thermal
electron impact excitation. Here we demonstrate that the observed line ratio
may be due to charge exchange and can be used to constrain the ion kinetic
energy to be <500 eV/u. This is accomplished by computing spectra and line
ratios via a range of theoretical methods and comparing these to experiments
with He over astrophysically relevant collision energies. The charge exchange
emission spectra calculations were performed for Ne[10+] +H and Ne[10+] +He
using widely applied approaches including the atomic orbital close coupling,
classical trajectory Monte Carlo, and multichannel Landau- Zener (MCLZ)
methods. A comparison of the results from these methods indicates that for the
considered energy range and neutrals (H, He) the so-called "low-energy
l-distribution" MCLZ method provides the most likely reliable predictions.


title: First Person Action-Object Detection with EgoNet

abstract:
  Unlike traditional third-person cameras mounted on robots, a first-person
camera, captures a person's visual sensorimotor object interactions from up
close. In this paper, we study the tight interplay between our momentary visual
attention and motor action with objects from a first-person camera. We propose
a concept of action-objects---the objects that capture person's conscious
visual (watching a TV) or tactile (taking a cup) interactions. Action-objects
may be task-dependent but since many tasks share common person-object spatial
configurations, action-objects exhibit a characteristic 3D spatial distance and
orientation with respect to the person.
  We design a predictive model that detects action-objects using EgoNet, a
joint two-stream network that holistically integrates visual appearance (RGB)
and 3D spatial layout (depth and height) cues to predict per-pixel likelihood
of action-objects. Our network also incorporates a first-person coordinate
embedding, which is designed to learn a spatial distribution of the
action-objects in the first-person data. We demonstrate EgoNet's predictive
power, by showing that it consistently outperforms previous baseline
approaches. Furthermore, EgoNet also exhibits a strong generalization ability,
i.e., it predicts semantically meaningful objects in novel first-person
datasets. Our method's ability to effectively detect action-objects could be
used to improve robots' understanding of human-object interactions.


title: Disk Outflows and High-Luminosity True Type 2 AGN

abstract:
  The absence of intrinsic broad line emission has been reported in a number of
active galactic nuclei (AGN), including some with high Eddington ratios. Such
"true type 2 AGN" are inherent to the disk-wind scenario for the broad line
region: Broad line emission requires a minimal column density, implying a
minimal outflow rate and thus a minimal accretion rate. Here we perform a
detailed analysis of the consequences of mass conservation in the process of
accretion through a central disk. The resulting constraints on luminosity are
consistent with all the cases where claimed detections of true type 2 AGN pass
stringent criteria, and predict that intrinsic broad line emission can
disappear at luminosities as high as about 4x$10^{46}$ erg s$^{-1}$ and any
Eddington ratio, though more detections can be expected at Eddington ratios
below about 1%. Our results are applicable to every disk outflow model,
whatever its details and whether clumpy or smooth, irrespective of the wind
structure and its underlying dynamics. While other factors, such as changes in
spectral energy distribution or covering factor, can affect the intensities of
broad emission lines, within this scenario they can only produce true type 2
AGN of higher luminosity then those prescribed by mass conservation.


title:
Multiple operator integrals, Haagerup and Haagerup-like tensor products,
  and operator ideals

abstract:
  We study Schatten--von Neumann properties of multiple operator integrals with
integrands in the Haagerup tensor product of $L^\infty$ spaces. We obtain
sharp, best possible estimates. This allowed us to obtain sharp Schatten--von
Neumann estimates in the case of {\it Haagerup-like} tensor products.


title: Obstacle avoidance via B-spline parameterizations of flat trajectories

abstract:
  This paper considers the collision avoidance problem in a multi-agent
multi-obstacle framework. The originality in solving this intensively studied
problem resides in the proposed geometrical view combined with differential
flatness for trajectory generation and B-splines for the flat output
parametrization. Using some important properties of these theoretical tools we
show that the constraints can be validated at all times. Exact and sub-optimal
constructions of the collision avoidance optimization problem are provided. The
results are validated through extensive simulations over standard autonomous
aerial vehicle dynamics.


title: Dynamic Data in the Statistics Classroom

abstract:
  The call for using real data in the classroom has long meant using datasets
which are culled, cleaned, and wrangled prior to any student working with the
observations. However, an important part of teaching statistics should include
actually retrieving data from the Internet. Nowadays, there are many different
sources of data that are continually updated by the organization hosting the
data website. The R tools to download such dynamic data have improved in such a
way to make accessing the data possible even in an introductory statistics
class. We provide five full analyses on dynamic data as well as an additional
nine sources of dynamic data that can be brought into the classroom. The goal
of our work is to demonstrate that using dynamic data can have a short learning
curve, even for introductory students or faculty unfamiliar with the landscape.
The examples provided are unlikely to create expert data scrapers, but they
should help motivate students and faculty toward more engaged use of online
data sources.


title:
Bilateral Boundary Control of One-Dimensional First- and Second-Order
  PDEs using Infinite-Dimensional Backstepping

abstract:
  This paper develops an extension of infinite-dimensional backstepping method
for parabolic and hyperbolic systems in one spatial dimension with two
actuators. Typically, PDE backstepping is applied in 1-D domains with an
actuator at one end. Here, we consider the use of two actuators, one at each
end of the domain, which we refer to as bilateral control (as opposed to
unilateral control). Bilateral control laws are derived for linear
reaction-diffusion, wave and 2X2 hyperbolic 1-D systems (with same speed of
transport in both directions). The extension is nontrivial but straightforward
if the backstepping transformation is adequately posed. The resulting bilateral
controllers are compared with their unilateral counterparts in the
reaction-diffusion case for constant coefficients, by making use of explicit
solutions, showing a reduction in control effort as a tradeoff for the presence
of two actuators when the system coefficients are large. These results open the
door for more sophisticated designs such as bilateral sensor/actuator output
feedback and fault-tolerant designs.


title:
Boundary Control of Coupled Reaction-Advection-Diffusion Systems with
  Spatially-Varying Coefficients

abstract:
  Recently, the problem of boundary stabilization for unstable linear
constant-coefficient coupled reaction-diffusion systems was solved by means of
the backstepping method. The extension of this result to systems with advection
terms and spatially-varying coefficients is challenging due to complex boundary
conditions that appear in the equations verified by the control kernels. In
this paper we address this issue by showing that these equations are
essentially equivalent to those verified by the control kernels for first-order
hyperbolic coupled systems, which were recently found to be well-posed. The
result therefore applies in this case, allowing us to prove H^1 stability for
the closed-loop system. It also shows an interesting connection between
backstepping kernels for coupled parabolic and hyperbolic problems.


title:
Safe Learning of Regions of Attraction for Uncertain, Nonlinear Systems
  with Gaussian Processes

abstract:
  Control theory can provide useful insights into the properties of controlled,
dynamic systems. One important property of nonlinear systems is the region of
attraction (ROA), a safe subset of the state space in which a given controller
renders an equilibrium point asymptotically stable. The ROA is typically
estimated based on a model of the system. However, since models are only an
approximation of the real world, the resulting estimated safe region can
contain states outside the ROA of the real system. This is not acceptable in
safety-critical applications. In this paper, we consider an approach that
learns the ROA from experiments on a real system, without ever leaving the true
ROA and, thus, without risking safety-critical failures. Based on regularity
assumptions on the model errors in terms of a Gaussian process prior, we use an
underlying Lyapunov function in order to determine a region in which an
equilibrium point is asymptotically stable with high probability. Moreover, we
provide an algorithm to actively and safely explore the state space in order to
expand the ROA estimate. We demonstrate the effectiveness of this method in
simulation.


title: Stars on trees

abstract:
  For a positive integer $r$ and a vertex $v$ of a graph $G$, let
$\mathcal{I}_G^{(r)}(v)$ denote the set of all independent sets of $G$ that
have exactly $r$ elements and contain $v$. Hurlbert and Kamat conjectured that
for any $r$ and any tree $T$, there exists a leaf $z$ of $T$ such that
$|\mathcal{I}_T^{(r)}(v)| \leq |\mathcal{I}_T^{(r)}(z)|$ for each vertex $v$ of
$T$. They proved the conjecture for $r \leq 4$. For any $k \geq 3$, we
construct a tree $T_k$ that has a vertex $x$ such that $x$ is not a leaf of
$T_k$, $|\mathcal{I}_{T_k}^{(r)}(z)| < |\mathcal{I}_{T_k}^{(r)}(x)|$ for any
leaf $z$ of $T_k$ and any $5 \leq r \leq 2k+1$, and $2k+1$ is the largest
integer $s$ for which $\mathcal{I}_{T_k}^{(s)}(x)$ is non-empty. Therefore, the
conjecture is not true for $r \geq 5$.


title: Splines and Wavelets on Circulant Graphs

abstract:
  We present novel families of wavelets and associated filterbanks for the
analysis and representation of functions defined on circulant graphs. In this
work, we leverage the inherent vanishing moment property of the circulant graph
Laplacian operator, and by extension, the e-graph Laplacian, which is
established as a parameterization of the former with respect to the degree per
node, for the design of vertex-localized and critically-sampled higher-order
graph (e-)spline wavelet filterbanks, which can reproduce and annihilate
classes of (exponential) polynomial signals on circulant graphs. In addition,
we discuss similarities and analogies of the detected properties and resulting
constructions with splines and spline wavelets in the Euclidean domain.
Ultimately, we consider generalizations to arbitrary graphs in the form of
graph approximations, with focus on graph product decompositions. In
particular, we proceed to show how the use of graph products facilitates a
multi-dimensional extension of the proposed constructions and properties.


title: Data Clustering and Graph Partitioning via Simulated Mixing

abstract:
  Spectral clustering approaches have led to well-accepted algorithms for
finding accurate clusters in a given dataset. However, their application to
large-scale datasets has been hindered by computational complexity of
eigenvalue decompositions. Several algorithms have been proposed in the recent
past to accelerate spectral clustering, however they compromise on the accuracy
of the spectral clustering to achieve faster speed. In this paper, we propose a
novel spectral clustering algorithm based on a mixing process on a graph.
Unlike the existing spectral clustering algorithms, our algorithm does not
require computing eigenvectors. Specifically, it finds the equivalent of a
linear combination of eigenvectors of the normalized similarity matrix weighted
with corresponding eigenvalues. This linear combination is then used to
partition the dataset into meaningful clusters. Simulations on real datasets
show that partitioning datasets based on such linear combinations of
eigenvectors achieves better accuracy than standard spectral clustering methods
as the number of clusters increase. Our algorithm can easily be implemented in
a distributed setting.


title:
Planck intermediate results. XLIII. The spectral energy distribution of
  dust in clusters of galaxies

abstract:
  Although infrared (IR) overall dust emission from clusters of galaxies has
been statistically detected using data from the Infrared Astronomical Satellite
(IRAS), it has not been possible to sample the spectral energy distribution
(SED) of this emission over its peak, and thus to break the degeneracy between
dust temperature and mass. By complementing the IRAS spectral coverage with
Planck satellite data from 100 to 857 GHz, we provide new constraints on the IR
spectrum of thermal dust emission in clusters of galaxies. We achieve this by
using a stacking approach for a sample of several hundred objects from the
Planck cluster sample; this procedure averages out fluctuations from the IR
sky, allowing us to reach a significant detection of the faint cluster
contribution. We also use the large frequency range probed by Planck, together
with component-separation techniques, to remove the contamination from both
cosmic microwave background anisotropies and the thermal Sunyaev-Zeldovich
effect (tSZ) signal, which dominate below 353 GHz. By excluding dominant
spurious signals or systematic effects, averaged detections are reported at
frequencies between 353 and 5000 GHz. We confirm the presence of dust in
clusters of galaxies at low and intermediate redshifts, yielding an SED with a
shape similar to that of the Milky Way. Planck's beam does not allow us to
investigate the detailed spatial distribution of this emission (e.g., whether
it comes from intergalactic dust or simply the dust content of the cluster
galaxies), but the radial distribution of the emission appears to follow that
of the stacked SZ signal, and thus the extent of the clusters. The recovered
SED allows us to constrain the dust mass responsible for the signal, as well as
its temperature. We additionally explore the evolution of the IR emission as a
function of cluster mass and redshift.


title:
Temporal upscaling in micro magnetism via heterogeneous multiscale
  methods

abstract:
  We consider a multiscale strategy addressing the disparate scales in the
Landau-Lifschitz equations in micro-magnetism. At the microscopic scale, the
dynamics of magnetic moments are driven by a high frequency field. On the
macroscopic scale we are interested in simulating the dynamics of the
magnetisation without fully resolving the microscopic scales.
  The method follows the framework of heterogeneous multiscale methods and it
has two main ingredients: a micro- and a macroscale model. The microscopic
model is assumed to be known exactly whereas the macro model is incomplete as
it lacks effective quantities. The two models use different temporal and
spatial scales and effective parameter values for the macro model are computed
on the fly, allowing for improved efficiency over traditional one-scale
schemes.
  For the analysis, we consider a single spin under a high frequency field and
show that effective quantities can be obtained accurately with step-sizes much
larger than the size of the microscopic scales required to resolve the
microscopic features. Numerical results both for a single magnetic particle as
well as a chain of interacting magnetic particles are given to validate the
theory.


title:
The Effect of Next-Nearest Neighbour Hopping in the One, Two, and Three
  Dimensional Holstein Model

abstract:
  Allowing a single electron to hop to next-nearest neighbours (NNN) in
addition to the closest atomic sites in the Holstein model, a modified Trugman
method is applied to exactly calculate the effect on the polaronic effective
mass in one, two, and three dimensions, building on the previous study of the
one-dimensional NNN Holstein model. We also present perturbative calculations
and a heuristic scaling factor for the coupling strength and ion frequency to
nearly map the NNN Holstein model back onto the original Holstein model. When
account is taken of the modified electronic bandwidth near the electron energy,
we find that including NNN hopping effectively increases the polaron effective
mass.


title:
DeepContext: Context-Encoding Neural Pathways for 3D Holistic Scene
  Understanding

abstract:
  While deep neural networks have led to human-level performance on computer
vision tasks, they have yet to demonstrate similar gains for holistic scene
understanding. In particular, 3D context has been shown to be an extremely
important cue for scene understanding - yet very little research has been done
on integrating context information with deep models. This paper presents an
approach to embed 3D context into the topology of a neural network trained to
perform holistic scene understanding. Given a depth image depicting a 3D scene,
our network aligns the observed scene with a predefined 3D scene template, and
then reasons about the existence and location of each object within the scene
template. In doing so, our model recognizes multiple objects in a single
forward pass of a 3D convolutional neural network, capturing both global scene
and local object information simultaneously. To create training data for this
3D network, we generate partly hallucinated depth images which are rendered by
replacing real objects with a repository of CAD models of the same object
category. Extensive experiments demonstrate the effectiveness of our algorithm
compared to the state-of-the-arts. Source code and data are available at
http://deepcontext.cs.princeton.edu.


title: On the number of alternating paths in bipartite complete graphs

abstract:
  Let $C \subseteq [r]^m$ be a code such that any two words of $C$ have Hamming
distance at least $t$. It is not difficult to see that determining a code $C$
with the maximum number of words is equivalent to finding the largest $n$ such
that there is an $r$-edge-coloring of $K_{m, n}$ with the property that any
pair of vertices in the class of size $n$ has at least $t$ alternating paths
(with adjacent edges having different colors) of length $2$. In this paper we
consider a more general problem from a slightly different direction. We are
interested in finding maximum $t$ such that there is an $r$-edge-coloring of
$K_{m,n}$ such that any pair of vertices in class of size $n$ is connected by
$t$ internally disjoint and alternating paths of length $2k$. We also study a
related problem in which we drop the assumption that paths are internally
disjoint. Finally, we introduce a new concept, which we call alternating
connectivity. Our proofs make use of random colorings combined with some
integer programs.


title: WKB and Resurgence in the Mathieu Equation

abstract:
  In this paper, based on lectures by the authors at the May 2015 workshop {\it
Resurgence, Physics and Numbers}, at the Centro di Ricerca Matematica Ennio De
Giorgio of the Scuola Normale Superiore in Pisa, we explain the origin of
resurgent trans-series in the Mathieu equation spectral problem, using uniform
WKB and all-orders (exact) WKB. Exact quantization conditions naturally arise,
and their expansion in the weak coupling regime produces resurgent trans-series
expressions which exhibit precise relations between different instanton
sectors. Indeed, the perturbative expansion encodes all orders of the
multi-instanton expansion, an explicit realization of the general concept of
"resurgence". We also discuss the transition from weak to strong coupling, an
explicit realization of "instanton condensation".


title: Physics of a toy geyser

abstract:
  A geyser can be reproduced by a toy experiment composed of a water pool
located above a water reservoir, the two being connected by a long and narrow
tube. When the bottom reservoir is heated, the system experiences periodic
eruptions of hot water and steam at the top similarly to the geyser effect
occurring in nature. The eruption frequency of a toy geyser is inspected
experimentally as a function of the heating power and the height of the set-up.
We propose a thermodynamic model of this system which predicts the time between
eruptions. Besides, the geometric and thermodynamic conditions required to
observe a geyser effect are discussed. The study of the toy geyser is then
extended to the case of two reservoirs connected to the same tube. In such a
configuration, an eruption in a reservoir may entrain the eruption of the
other. Such a coupled system adopts a complex time-evolution which reflects the
dynamics of natural geysers. We analyze the behavior of a toy geyser with two
reservoirs by the way of statistical tools and develop a theoretical model in
order to rationalize our observations.


title: Equivariant $K$-theory of smooth projective spherical varieties

abstract:
  We present a description of the equivariant $K$-theory of a smooth projective
spherical variety. This provides an integral $K$-theory version of Brion's
calculation of equivariant Chow-cohomology of such varieties. We consider the
equivariant $K$-theory of wonderful compactifications of minimal rank symmetric
varieties. We obtain a formula for their structure constants in terms of
certain lower dimensional Schubert classes. This generalizes results of Uma on
equivariant compactifications of adjoint groups.


title:
Maximal Function Characterizations of Musielak-Orlicz-Hardy Spaces
  Associated to Non-negative Self-adjoint Operators Satisfying Gaussian
  Estimates

abstract:
  Let $L$ be a non-negative self-adjoint operator on $L^2(\mathbb{R}^n)$ whose
heat kernels have the Gaussian upper bound estimates. Assume that the growth
function $\varphi:\,\mathbb{R}^n\times[0,\infty) \to[0,\infty)$ satisfies that
$\varphi(x,\cdot)$ is an Orlicz function and $\varphi(\cdot,t)\in {\mathbb
A}_{\infty}(\mathbb{R}^n)$ (the class of uniformly Muckenhoupt weights). Let
$H_{\varphi,\,L}(\mathbb{R}^n)$ be the Musielak-Orlicz-Hardy space introduced
via the Lusin area function associated with the heat semigroup of $L$. In this
article, the authors obtain several maximal function characterizations of the
space $H_{\varphi,\,L}(\mathbb{R}^n)$, which, especially, answer an open
question of L. Song and L. Yan under an additional mild assumption satisfied by
Schr\"odinger operators on $\mathbb{R}^n$ with non-negative potentials
belonging to the reverse H\"older class, and second-order divergence form
elliptic operators on $\mathbb{R}^n$ with bounded measurable real coefficients.


title:
Energy Probability Distribution Zeros: A Route to Study Phase
  Transitions

abstract:
  In the study of phase transitions a very few models are accessible to exact
solution. In the most cases analytical simplifications have to be done or some
numerical technique has to be used to get insight about their critical
properties. Numerically, the most common approaches are those based in Monte
Carlo simulations together finite size scaling analysis. The use of Monte Carlo
techniques requires the estimate of quantities like the specific heat or
susceptibilities in a wide range of temperature or the construction of the
density of states in large intervals of energy. Although many of these
techniques are well developed they may be very time consuming when the system
size becomes large enough. It should be suitable to have a method that could
surpass those difficulties.
  In this work we present an iterative method to study the critical behavior of
a system based on the partial knowledge of the complex Fisher zeros set of the
partition function. The method is general with advantages over most
conventional techniques since it does not need to identify any order parameter
\emph{a priori}. The critical temperature and exponents can be obtained with
great precision even in the most unamenable cases like the two dimensional $XY$
model. To test the method and to show how it works we applied it to some
selected models where the transitions are well known: The 2D Ising, Potts and
XY models and to a homopolymer system. Our choice cover systems with first
order, continuous and Berezinskii-Kosterlitz-Thouless transitions as well as
the homopolymer that has two pseudo-transitions. The strategy can easily be
adapted to any model, classical or quantum, once we are able to build the
corresponding energy probability distribution.


title: Statistical Inference

abstract:
  What is Statistics? Opinions vary. In fact, there is a continuous spectrum of
attitudes toward statistics ranging from pure theoreticians, proving asymptotic
efficiency and searching for most powerful tests, to wild practitioners,
blindly reporting p-values and claiming statistical significance for
scientifically insignificant results. In these notes statistics is viewed as a
branch of mathematical engineering, that studies ways of extracting reliable
information from limited data for learning, prediction, and decision making in
the presence of uncertainty. These ACM lecture notes are based on the courses
the author taught at the University of Southern California in 2012 and 2013,
and at the California Institute of Technology in 2016.


title: Deep Fully-Connected Networks for Video Compressive Sensing

abstract:
  In this work we present a deep learning framework for video compressive
sensing. The proposed formulation enables recovery of video frames in a few
seconds at significantly improved reconstruction quality compared to previous
approaches. Our investigation starts by learning a linear mapping between video
sequences and corresponding measured frames which turns out to provide
promising results. We then extend the linear formulation to deep
fully-connected networks and explore the performance gains using deeper
architectures. Our analysis is always driven by the applicability of the
proposed framework on existing compressive video architectures. Extensive
simulations on several video sequences document the superiority of our approach
both quantitatively and qualitatively. Finally, our analysis offers insights
into understanding how dataset sizes and number of layers affect reconstruction
performance while raising a few points for future investigation.
  Code is available at Github: https://github.com/miliadis/DeepVideoCS


title:
Effects of Sensemaking Translucence on Distributed Collaborative
  Analysis

abstract:
  Collaborative sensemaking requires that analysts share their information and
insights with each other, but this process of sharing runs the risks of
prematurely focusing the investigation on specific suspects. To address this
tension, we propose and test an interface for collaborative crime analysis that
aims to make analysts more aware of their sensemaking processes. We compare our
sensemaking translucence interface to a standard interface without special
sensemaking features in a controlled laboratory study. We found that the
sensemaking translucence interface significantly improved clue finding and
crime solving performance, but that analysts rated the interface lower on
subjective measures than the standard interface. We conclude that designing for
distributed sensemaking requires balancing task performance vs. user experience
and real-time information sharing vs. data accuracy.


title:
Unfolding homoclinic connections formed by corner intersections in
  piecewise-smooth maps

abstract:
  The stable and unstable manifolds of an invariant set of a piecewise-smooth
map are themselves piecewise-smooth. Consequently, as parameters of a
piecewise-smooth map are varied, an invariant set can develop a homoclinic
connection when its stable manifold intersects a non-differentiable point of
its unstable manifold (or vice-versa). This is a codimension-one bifurcation
analogous to a homoclinic tangency of a smooth map, referred to here as a
homoclinic corner. This paper presents an unfolding of generic homoclinic
corners for saddle fixed points of planar piecewise-smooth continuous maps. It
is shown that a sequence of border-collision bifurcations limits to a
homoclinic corner and that all nearby periodic solutions are unstable.


title: A note on linear B-spline copulas

abstract:
  In this brief note we prove that linear B-spline copulas is not a new family
of copulas since they are equivalent to checkerboard copulas, and discuss in
particular how they are used to extend empirical subcopulas to copulas.


title:
Multiple Hot-Carrier Collection in Photo-Excited Graphene Moire
  Superlattices

abstract:
  In conventional light harvesting devices, the absorption of a single photon
only excites one electron, which sets the standard limit of power-conversion
efficiency, such as the Shockley-Queisser limit. In principle, generating and
harnessing multiple carriers per absorbed photon can improve the efficiency and
possibly overcome this limit. Here, we report the observation of multiple hot
carrier collection in graphene-boron-nitride Moire superlattice structures. A
record-high zero-bias photoresponsivity of 0.3 ampere per watt, equivalently,
an external quantum efficiency exceeding 50 percent, is achieved utilizing
graphene photo-Nernst effect, which demonstrates a collection of at least 5
carriers per absorbed photon. We reveal that this effect arises from the
enhanced Nernst coefficient through Lifshtiz transition at low energy Van Hove
singularities, which is an emergent phenomenon due to the formation of Moire
minibands. Our observation points to a new means for extremely efficient and
flexible optoelectronics based on van der Waals heterostructures.


title:
Lowest sl(2)-types in sl(n)-representations with respect to a principal
  embedding

abstract:
  Fix n>2. Let s be a principally embedded sl(2)-subalgebra in sl(n). A special
case of results of the second author and Gregg Zuckerman implies that there
exists a positive integer b(n) such that for any finite dimensional
sl(n)-representation, V, there exists an irreducible s-representation embedding
in V with dimension at most b(n). We prove that b(n)=n is the sharpest possible
bound. We also address embeddings other than the principal one.
  The exposition involves an application of the Cartan--Helgason theorem, Pieri
rules, Hermite reciprocity, and a calculation in the "branching algebra"
introduced by Roger Howe, Eng-Chye Tan, and the second author.


title:
Observation of $h_{c}$ radiative decay $h_{c} \rightarrow \gamma \eta'$
  and evidence for $h_{c} \rightarrow \gamma \eta$

abstract:
  A search for radiative decays of the $P$-wave spin singlet charmonium
resonance $h_c$ is performed based on $4.48 \times 10^{8}$ $\psi'$ events
collected with the BESIII detector operating at the BEPCII storage ring. Events
of the reaction channels $h_{c} \rightarrow \gamma \eta'$ and $\gamma \eta$ are
observed with a statistical significance of $8.4 \sigma$ and $4.0 \sigma$,
respectively, for the first time. The branching fractions of $h_{c} \rightarrow
\gamma \eta'$ and $h_{c} \rightarrow \gamma \eta$ are measured to be
$\mathcal{B}(h_{c} \rightarrow \gamma \eta')=(1.52 \pm 0.27 \pm
0.29)\times10^{-3}$ and $\mathcal{B}(h_{c} \rightarrow \gamma \eta)=(4.7 \pm
1.5 \pm 1.4)\times10^{-4}$, respectively, where the first errors are
statistical and the second are systematic uncertainties.


title: Julia sets of Orthogonal polynomials

abstract:
  For a probability measure with compact and non-polar support in the complex
plane we relate dynamical properties of the associated sequence of orthogonal
polynomials $\{P_n\}$ to properties of the support. More precisely we relate
the Julia set of $P_n$ to the outer boundary of the support, the filled Julia
set to the polynomial convex hull $K$ of the support, and the Green's function
associated with $P_n$ to the Green's function for the complement of $K$.


title: Linear Hypergraph Edge Coloring

abstract:
  Motivated by the Erdos-Faber Lovasz conjecture (EFL) for hypergraphs, we
explore relationships between several conjectures on the edge coloring of
linear hypergraphs. In particular, we are able to increase the class of
hypergraphs for which EFL is true.


title:
Grand challenges in altmetrics: heterogeneity, data quality and
  dependencies

abstract:
  As uptake among researchers is constantly increasing, social media are
finding their way into scholarly communication and, under the umbrella term
altmetrics, were introduced to research evaluation. Fueled by technological
possibilities and an increasing demand to demonstrate impact beyond the
scientific community, altmetrics received great attention as potential
democratizers of the scientific reward system and indicators of societal
impact. This paper focuses on current challenges of altmetrics. Heterogeneity,
data quality and particular dependencies are identified as the three major
issues and discussed in detail with a particular emphasis on past developments
in bibliometrics. The heterogeneity of altmetrics mirrors the diversity of the
types of underlying acts, most of which take place on social media platforms.
This heterogeneity has made it difficult to establish a common definition or
conceptual framework. Data quality issues become apparent in the lack of
accuracy, consistency and replicability of various altmetrics, which is largely
affected by the dynamic nature of social media events. It is further
highlighted that altmetrics are shaped by technical possibilities and depend
particularly on the availability of APIs and DOIs, are strongly dependent on
data providers and aggregators, and potentially influenced by technical
affordances of underlying platforms.


title:
An indefinite concave-convex equation under a Neumann boundary condition
  I

abstract:
  We investigate the problem $$-\Delta u = \lambda b(x)|u|^{q-2}u
+a(x)|u|^{p-2}u \mbox{ in } \Omega, \quad \frac{\partial u}{\partial
\mathbf{n}} = 0 \mbox{ on } \partial \Omega, \leqno{(P_\lambda)} $$ where
$\Omega$ is a bounded smooth domain in $\mathbb{R}^N$ ($N \geq2$), $1<q<2<p$,
$\lambda \in \mathbb{R}$, and $a,b \in C^\alpha(\overline{\Omega})$ with
$0<\alpha<1$. Under some indefinite type conditions on $a$ and $b$ we prove the
existence of two nontrivial non-negative solutions for $|\lambda|$ small. We
characterize then the asymptotic profiles of these solutions as $\lambda \to
0$, which implies in some cases the positivity and ordering of these solutions.
In addition, this asymptotic analysis suggests the existence of a loop type
subcontinuum in the non-negative solutions set. We prove in some cases the
existence of such subcontinuum via a bifurcation and topological analysis of a
regularized version of $(P_\lambda)$.


title: Parallel Algorithms for Select and Partition with Noisy Comparisons

abstract:
  We consider the problem of finding the $k^{th}$ highest element in a totally
ordered set of $n$ elements (select), and partitioning a totally ordered set
into the top $k$ and bottom $n-k$ elements (partition) using pairwise
comparisons. Motivated by settings like peer grading or crowdsourcing, where
multiple rounds of interaction are costly and queried comparisons may be
inconsistent with the ground truth, we evaluate algorithms based both on their
total runtime and the number of interactive rounds in three comparison models:
noiseless (where the comparisons are correct), erasure (where comparisons are
erased with probability $1-\gamma$), and noisy (where comparisons are correct
with probability $1/2+\gamma/2$ and incorrect otherwise). We provide numerous
matching upper and lower bounds in all three models. Even our results in the
noiseless model, which is quite well-studied in the TCS literature on parallel
algorithms, are novel.


title: THz based phase space manipulation in a zero-slippage IFEL

abstract:
  We describe an IFEL interaction driven by a guided broadband THz source to
compress a relativistic electron bunch and synchronize it with an external
laser pulse. A high field near single-cycle THz pulse, generated via optical
rectification from the external laser source, is group velocity-matched to the
electron bunch inside a waveguide, allowing for a sustained interaction in a
magnetic undulator. We present measurements of the THz waveform before and
after a curved parallel plate waveguide with varying aperture size and estimate
the reduced group velocity. For a proof-of-concept experiment at the UCLA
PEGASUS laboratory, a 6 MeV, 100 fs electron bunch with an initial 0.03 %
energy spread can be readily produced. Given these parameters and a projected
THz peak field of 10 MV/m, our simulation model predicts a phase space rotation
of the bunch distribution that compresses the electron bunch by nearly an order
of magnitude and reduces any initial timing jitter within the phase acceptance
window. We also discuss the application of this guided-THz IFEL experimental
set-up towards a THz streaking diagnostic with the potential for femtosecond
scale temporal resolution.


title: Dynamics of galaxies and clusters in \textit{refracted gravity}

abstract:
  We investigate the proof of concept and the implications of \textit{refracted
gravity}, a novel modified gravity aimed to solve the discrepancy between the
luminous and the dynamical mass of cosmic structures without resorting to dark
matter. Inspired by the behavior of electric fields in matter, refracted
gravity introduces a gravitational permittivity that depends on the local mass
density and modifies the standard Poisson equation. The resulting gravitational
field can become more intense than the Newtonian field and can mimic the
presence of dark matter. We show that the refracted gravitational field
correctly describes (1) the rotation curves and the Tully-Fisher relation of
disk galaxies; and (2) the observed temperature profile of the X-ray gas of
galaxy clusters. According to these promising results, we conclude that
refracted gravity deserves further investigation.


title: A note on refracted L\'evy processes without positive jumps

abstract:
  For a refracted spectrally negative Levy process, we find some new and
fantastic formulas for its q-potential measures without killing. Unlike
previous results, which are written in terms of the known q-scale functions,
our formulas are free of the q-scale functions. This makes our results become
extremely important since it is likely that our formulas also hold for a
general refracted Levy process.


title:
Instability of group formation through indirect reciprocity under
  imperfect information and implementation error

abstract:
  Indirect reciprocity is a key mechanism behind the evolution of cooperation.
Oishi et al. analytically showed the formation of two exclusive groups under
the KANDORI assessment rule in the case of perfect information and no
implementation error, regardless of the population size $N$. Here, we
numerically show the formation of many exclusive groups under the JUDGING
assessment rule in the same case. Introducing degrees of exclusive groups, we
numerically examine the stability of the group formation under imperfect
information and implementation error.


title: Mean-field study of $^{12}$C+$^{12}$C fusion

abstract:
  The nuclear mean-field potential arising from the $^{12}$C+$^{12}$C
interaction at the low energies relevant for the astrophysical carbon burning
process has been constructed within the double-folding model, using the
realistic nuclear ground-state density of the $^{12}$C nucleus and the
effective M3Y nucleon-nucleon (NN) interaction constructed from the G-matrix of
the Paris (free) NN potential. To explore the nuclear medium effect, both the
original density independent M3Y-Paris interaction and its density dependent
CDM3Y6 version have been used in the folding model calculation of the
$^{12}$C+$^{12}$C potential. The folded potentials at the different energies
were used in the optical model description of the elastic $^{12}$C+$^{12}$C
scattering at the energies around and below the Coulomb barrier, as well as in
the barrier penetration model to estimate the fusion cross section and
astrophysical $S$ factor of the $^{12}$C+$^{12}$C reactions at the low
energies. The obtained results are in good agreement with experimental data
over a wide range of energies.


title: On the Complexity of One-class SVM for Multiple Instance Learning

abstract:
  In traditional multiple instance learning (MIL), both positive and negative
bags are required to learn a prediction function. However, a high human cost is
needed to know the label of each bag---positive or negative. Only positive bags
contain our focus (positive instances) while negative bags consist of noise or
background (negative instances). So we do not expect to spend too much to label
the negative bags. Contrary to our expectation, nearly all existing MIL methods
require enough negative bags besides positive ones. In this paper we propose an
algorithm called "Positive Multiple Instance" (PMI), which learns a classifier
given only a set of positive bags. So the annotation of negative bags becomes
unnecessary in our method. PMI is constructed based on the assumption that the
unknown positive instances in positive bags be similar each other and
constitute one compact cluster in feature space and the negative instances
locate outside this cluster. The experimental results demonstrate that PMI
achieves the performances close to or a little worse than those of the
traditional MIL algorithms on benchmark and real data sets. However, the number
of training bags in PMI is reduced significantly compared with traditional MIL
algorithms.


title: Some remarks on sets with small quotient set

abstract:
  We prove, in particular, that for any finite set of real numbers A with |A/A|
\ll |A| one has |A-A| > |A|^{5/3 - o(1)}. Also we show that |3A| > |A|^{2-o(1)}
in the case.


title:
A Reduced Order Direct Coupling Coherent Quantum Observer for a Complex
  Quantum Plant

abstract:
  This paper extends previous results on constructing a direct coupling quantum
observer for a quantum harmonic oscillator system. In this case, we consider a
complex linear quantum system plant consisting of a network of quantum harmonic
oscillators. Conditions are given for which there exists a direct coupling
observer which estimates a collection of variables in the quantum plant. It is
shown that the order of the observer can be the same as the number of variables
to be estimated when this number is even and thus this is a reduced order
observer.


title: Quantum Linear Systems Theory

abstract:
  This paper surveys some recent results on the theory of quantum linear
systems and presents them within a unified framework. Quantum linear systems
are a class of systems whose dynamics, which are described by the laws of
quantum mechanics, take the specific form of a set of linear quantum stochastic
differential equations (QSDEs). Such systems commonly arise in the area of
quantum optics and related disciplines. Systems whose dynamics can be described
or approximated by linear QSDEs include interconnections of optical cavities,
beam-spitters, phase-shifters, optical parametric amplifiers, optical
squeezers, and cavity quantum electrodynamic systems. With advances in quantum
technology, the feedback control of such quantum systems is generating new
challenges in the field of control theory. Potential applications of such
quantum feedback control systems include quantum computing, quantum error
correction, quantum communications, gravity wave detection, metrology, atom
lasers, and superconducting quantum circuits.
  A recently emerging approach to the feedback control of quantum linear
systems involves the use of a controller which itself is a quantum linear
system. This approach to quantum feedback control, referred to as coherent
quantum feedback control, has the advantage that it does not destroy quantum
information, is fast, and has the potential for efficient implementation. This
paper discusses recent results concerning the synthesis of H-infinity optimal
controllers for linear quantum systems in the coherent control case. An
important issue which arises both in the modelling of linear quantum systems
and in the synthesis of linear coherent quantum controllers is the issue of
physical realizability. This issue relates to the property of whether a given
set of QSDEs corresponds to a physical quantum system satisfying the laws of
quantum mechanics.


title:
Data-driven Radiative Hydrodynamic Modeling of the 2014 March 29 X1.0
  Solar Flare

abstract:
  Spectroscopic observations of solar flares provide critical diagnostics of
the physical conditions in the flaring atmosphere. Some key features in
observed spectra have not yet been accounted for in existing flare models. Here
we report a data-driven simulation of the well-observed X1.0 flare on 2014
March 29 that can reconcile some well-known spectral discrepancies. We analyzed
spectra of the flaring region from the Interface Region Imaging Spectrograph
(IRIS) in MgII h&k, the Interferometric BIdimensional Spectropolarimeter at the
Dunn Solar Telescope (DST/IBIS) in H$\alpha$ 6563 \AA\ and CaII 8542 \AA, and
the Reuven Ramaty High Energy Solar Spectroscope Imager (RHESSI) in hard
X-rays. We constructed a multi-threaded flare loop model and used the electron
flux inferred from RHESSI data as the input to the radiative hydrodynamic code
RADYN to simulate the atmospheric response. We then synthesized various
chromospheric emission lines and compared them with the IRIS and IBIS
observations. In general, the synthetic intensities agree with the observed
ones, especially near the northern footpoint of the flare. The simulated MgII
line profile has narrower wings than the observed one. This discrepancy can be
reduced by using a higher microturbulent velocity (27 km/s) in a narrow
chromospheric layer. In addition, we found that an increase of electron density
in the upper chromosphere within a narrow height range of $\approx$800 km below
the transition region can turn the simulated MgII line core into emission and
thus reproduce the single peaked profile, which is a common feature in all IRIS
flares.


title:
Magnetic Properties Controlled by Interstitial or Interlayer Cations in
  Iron Chalcogenides

abstract:
  By applying density functional theory calculations to iron chalcogenides, we
find that magnetic order in Fe$_{1+y}$Te and magnetic instability at
$(\pi,\pi)$ in K$_y$Fe$_2$Se$_2$ are controlled by interstitial and interlayer
cations, respectively. While in Fe$_{1+y}$Te, magnetic phase transitions occur
among collinear, exotic bicollinear and plaquette-ordered antiferronmagnetic
states when the height of interstitial irons measured from iron plane or the
concentration of interstitial irons is varied, the magnetic instability at
$(\pi,\pi)$ which is believed to be responsible for the Cooper pairing in iron
pnictides is significantly enhanced when $y$ is much smaller than $1$ in
K$_y$Fe$_2$Se$_2$. Our results indicate that, similar to iron pnictides,
itinerant electrons play important roles in iron chalcogenides, even though the
fluctuating local moments become larger.


title:
Mitigation Procedures to Rank Experts through Information Retrieval
  Measures

abstract:
  In order to find experts, different approaches build rankings of people,
assuming that they are ranked by level of expertise, and use typical
Information Retrieval (IR) measures to evaluate their effectiveness. However,
we figured out that expert rankings (i) tend to be partially ordered, (ii)
incomplete, and (iii) consequently provide more an order rather than absolute
ranks, which is not what usual IR measures exploit. To improve this state of
the art, we propose to revise the formalism used in IR to design proper
measures for comparing expert rankings. In this report, we investigate a first
step by providing mitigation procedures for the three issues, and we analyse IR
measures with the help of these procedures to identify interesting revisions
and remaining limitations. From this analysis, we see that most of the measures
can be exploited for this more generic context because of our mitigation
procedures. Moreover, measures based on precision and recall, usually unable to
consider the order of the ranked items, are of first interest if we represent a
ranking as a set of ordered pairs. Cumulative measures, on the other hand, are
specifically designed for considering the order but suffer from a higher
complexity, motivating the use of precision/recall measures with the right
representation.


title:
Online Optimization in Dynamic Environments: Improved Regret Rates for
  Strongly Convex Problems

abstract:
  In this paper, we address tracking of a time-varying parameter with unknown
dynamics. We formalize the problem as an instance of online optimization in a
dynamic setting. Using online gradient descent, we propose a method that
sequentially predicts the value of the parameter and in turn suffers a loss.
The objective is to minimize the accumulation of losses over the time horizon,
a notion that is termed dynamic regret. While existing methods focus on convex
loss functions, we consider strongly convex functions so as to provide better
guarantees of performance. We derive a regret bound that captures the
path-length of the time-varying parameter, defined in terms of the distance
between its consecutive values. In other words, the bound represents the
natural connection of tracking quality to the rate of change of the parameter.
We provide numerical experiments to complement our theoretical findings.


title:
A Modified SEIR Model for the Spread of Ebola in Western Africa and
  Metrics for Resource Allocation

abstract:
  A modified, deterministic SEIR model is developed for the 2014 Ebola epidemic
occurring in the West African nations of Guinea, Liberia, and Sierra Leone. The
model describes the dynamical interaction of susceptible and infected
populations, while accounting for the effects of hospitalization and the spread
of disease through interactions with deceased, but infectious, individuals.
Using data from the World Health Organization (WHO), parameters within the
model are fit to recent estimates of infected and deceased cases from each
nation. The model is then analyzed using these parameter values. Finally,
several metrics are proposed to determine which of these nations is in greatest
need of additional resources to combat the spread of infection. These include
local and global sensitivity metrics of both the infected population and the
basic reproduction number with respect to rates of hospitalization and proper
burial.


title: Description for rotating $C_{60}$ fullerenes via G\"odel-type metric

abstract:
  In this contribution a geometric approach to describe a rotating fullerene
molecule with Ih symmetry is developed. We analyze the quantum dynamics of
quasiparticles in continuum limit considering a description of fullerene in a
spherical solution of the G\"odel-type space-time with a topological defect. As
a result, we study the molecule in a rotating frame. Also we combine the well
know non-Abelian monopole approach with this geometric description, including
the case of the presence of the external Aharonov-Bohm flux. The energy levels
and the persistent current for this study are obtained, and we show that they
depend on the geometrical and topological properties of the fullerene. Also, we
verify recovering of the well known results for limiting cases.


title: Stopping waveguide photons with controllable atomic cavity

abstract:
  Slowing/stopping the light travelling in free space with electromagnetically
induced transparency to im- plement the optical quantum information processings
and store information has been paid much attention in recent years. For the
waveguide photons, here, we propose an approach to stop them with a
controllable atomic cavity generated by a pair of atomic mirrors; one of them
reflects the photon completely and an- other one with the adjustable
reflected/transmitted probability of the photons. Based on the full quantum
mechanical theory in real space, we show that the reflected/transmitted
probability of the waveguide photon with a fixed frequency can be controlled by
adjusting the energy-splitting of the driven two-level atomic scatters (i.e.,
atomic mirrors). As a consequence, the photon can be controllably
transmitted/reflected along the waveguide by the aside atomic mirrors with the
adjustable atomic energy levels. Ideally, the photons could be stopped in the
atomic cavity. This provides a novel mechanism to stop/retravel the waveguide
photon in a controllable ways. The feasibility of the proposal with the current
integrated optical devices is also discussed.


title: Implications of imaginary chemical potential for model building of QCD

abstract:
  Properties of QCD at finite imaginary chemical potential are revisited to
utilize for the model building of QCD in low energy regimes. For example, the
electric holonomy which is closely related to the Polyakov-loop drastically
affects thermodynamic quantities beside the Roberge-Weiss transition line. To
incorporate several properties at finite imaginary chemical potential, it is
important to introduce the holonomy effects to the coupling constant of
effective models. This extension is possible by considering the entanglement
vertex. We show justifications of the entanglement vertex based on the
derivation of the effective four-fermi interaction in the Nambu--Jona-Lasinio
model and present its general form with the local approximation. To discuss how
to remove model ambiguities in the entanglement vertex, we calculate the chiral
condensate with different $\mathbb{Z}_3$ sectors and the dual quark condensate.


title: On the Bright Loop Top Emission in Post Eruption Arcades

abstract:
  The observations of post eruption arcades (PEAs) in X-rays and EUV reveal
strong localised brightenings at the loop top regions. The origin of these
brightenings and their dynamics is not well understood to date. Here, we study
the dynamics of PEAs using one-dimensional hydrodynamic modelling with the
focus on the the understanding of the formation of localised brightening.Our
findings suggest that these brightenings are the result of collisions between
the counter-streaming chromospheric evaporation from both the foot points. We
further perform forward modelling of the emission observed in simulated results
in various spectral lines observed by the Extreme-Ultraviolet Imaging Telescope
aboard Hinode. The forward modelled intensities in various spectral lines are
in close agreement with a flare observed in December 17, 2006 by EIS.


title: Local equilibrium in inhomogeneous stochastic models of heat transport

abstract:
  We extend the duality of Kipnis Marchioro and Presutti to inhomogeneous
lattice gas systems where either the components have different degrees of
freedom or the rate of interaction depends on the spatial location. Then the
dual process is applied to prove local equilibrium in the hydrodynamic limit
for some inhomogeneous high dimensional systems andin the nonequilibrium steady
state for one dimensional systems with arbitrary inhomogeneity.


title: Optical bandgap and bowing parameter for Fe doped LaGaO3

abstract:
  The polycrystalline samples of LaGa1-xFexO3 have been prepared by standard
solid state reaction route. The phase purity of the prepared samples is
confirmed by powder xray diffraction experiments followed by Rietveld analysis.
It has been observed that the variation of lattice parameters is governed by
Vegards law. The optical band gap of these samples is estimated using diffuse
reflectance analysis and it is observed that the optical gap systematically
decreases with Fe doping from 3.62 eV and attains the saturation value of
approximately 1.9 eV at x equal to 0.4. The value of the bowing parameter b for
the prepared solid solution LaGa1-xFexO3 is estimated to be 3.8eV.The xray
absorption near edge spectroscopy XANES suggests that the Fe is in mixed
valence state in all prepared samples and these mixed states of Fe due to
offstoichiometry acts like electron doping in LaGa1-xFexO3 and thereby results
in the reduction in the effective band gap. Our results may be useful to design
the LaGaO3based light emitting diodes and new generation of semiconductor
photo-detectors.


title: Nontrivial minimal surfaces in a hyperbolic Randers space

abstract:
  The contribution of this paper is two-fold. The first one is to derive a
simple formula of the mean curvature form for a hypersurface in the Randers
space with a Killing field, by considering the Busemann-Hausdorff measure and
Holmes-Thompson measure simultaneously. The second one is to obtain the
explicit local expressions of two types of nontrivial rotational BH-minimal
surfaces in a Randers domain of constant flag curvature $K=-1$, which are the
first examples of BH-minimal surfaces in the hyperbolic Randers space.


title: Gate-induced Gap in Bilayer Graphene Suppressed by Coulomb Repulsion

abstract:
  We investigate the effect of on-site Coulomb repulsion $U$ on the band gap of
the electrically gated bilayer graphene by employing coherent potential
approximation in the paramagnetic state, based on an ionic two-layer Hubbard
model. We find that, while either the on-site Coulomb repulsion $U$ or the
external perpendicular electric field $E$ alone will favor a gapped state in
the bilayer graphene, competition between them will surprisingly lead to a
suppression of the gap amplitude. Our results can be applied to understand the
discrepancies of gap size reported from optical and transport measurements, as
well as the puzzling features observed in angular resolved photoemission
spectroscopic study.


title: Optimal Remote State Estimation for Self-Propelled Particle Models

abstract:
  We investigate the design of a remote state estimation system for a
self-propelled particle (SPP). Our framework consists of a sensing unit that
accesses the full state of the SPP and an estimator that is remotely located
from the sensing unit. The sensing unit must pay a cost when it chooses to
transmit information on the state of the SPP to the estimator; and the
estimator computes the best estimate of the state of the SPP based on received
information. In this paper, we provide methods to design transmission policies
and estimation rules for the sensing unit and estimator, respectively, that are
optimal for a given cost functional that combines state estimation distortion
and communication costs. We consider two notions of optimality: joint
optimality and person-by-person optimality. Our main results show the existence
of a jointly optimal solution and describe an iterative procedure to find a
person-by-person optimal solution. In addition, we explain how the remote
estimation scheme can be applied to tracking of animal movements over a costly
communication link. We also provide experimental results to show the
effectiveness of the scheme.


title:
Magnetic properties of a two-dimensional electron gas strongly coupled
  to light

abstract:
  Considering the quantum dynamics of 2DEG exposed to both a stationary
magnetic field and an intense high-frequency electromagnetic wave, we found
that the wave decreases the scattering-induced broadening of Landau levels.
Therefore, various magnetoelectronic properties of two-dimensional
nanostructures (density of electronic states at Landau levels,
magnetotransport, etc) are sensitive to the irradiation by light. Thus, the
elaborated theory paves a way to optical controlling magnetic properties of
2DEG.


title:
Remarks on derivative nonlinear Schr\"odinger systems with multiple
  masses

abstract:
  We prove global existence of small solutions to the initial value problem for
a class of cubic derivative nonlinear Schr\"odinger systems with the masses
satisfying suitable non-resonance relations. The large-time asymptotics of the
solutions are also shown. This work is intended to provide a counterpart of the
previous paper (arXiv:1507.07617) in which the mass resonance case was treated.


title: Cosmic Dust VII

abstract: This is an editorial to the special issue on Cosmic Dust VII.


title: Hi-C Observations of Sunspot Penumbral Bright Dots

abstract:
  We report observations of bright dots (BDs) in a sunspot penumbra using High
Resolution Coronal Imager (Hi-C) data in 193 \AA\ and examine their sizes,
lifetimes, speeds, and intensities. The sizes of the BDs are on the order of
1\arcsec\ and are therefore hard to identify in the Atmospheric Imaging
Assembly (AIA) 193 \AA\ images, which have 1.2\arcsec\ spatial resolution, but
become readily apparent with Hi-C's five times better spatial resolution. We
supplement Hi-C data with data from AIA's 193 \AA\ passband to see the complete
lifetime of the BDs that appeared before and/or lasted longer than Hi-C's
3-minute observation period. Most Hi-C BDs show clear lateral movement along
penumbral striations, toward or away from the sunspot umbra. Single BDs often
interact with other BDs, combining to fade away or brighten. The BDs that do
not interact with other BDs tend to have smaller displacements. These BDs are
about as numerous but move slower on average than Interface Region Imaging
Spectrograph (IRIS) BDs, recently reported by \cite{tian14}, and the sizes and
lifetimes are on the higher end of the distribution of IRIS BDs. Using
additional AIA passbands, we compare the lightcurves of the BDs to test whether
the Hi-C BDs have transition region (TR) temperature like that of the IRIS BDs.
The lightcurves of most Hi-C BDs peak together in different AIA channels
indicating that their temperature is likely in the range of the cooler TR
($1-4\times 10^5$ K).


title:
Evolution of Temperature Fluctuation in a Thermal bath and, its
  implications in Hadronic and Heavy-Ion Collisions

abstract:
  The evolution equation for inhomogeneous and anisotropic temperature
fluctuations inside a medium is derived within the ambit of Boltzmann Transport
Equation. Also, taking some existing realistic inputs we have analyzed the
Fourier space variation of temperature fluctuation for the medium created after
heavy-ion collisions. The effect of viscosity on the variation of fluctuations
is investigated. Further, possible implications in hadronic and heavy-ion
collisions are explored.


title: The q-Statistics and QCD Thermodynamics at LHC

abstract:
  We perform a Taylor series expansion of Tsallis distribution by assuming the
Tsallis parameter $q$ close to 1. The $q$ value shows the deviation of a system
from a thermalised Boltzmann distribution. By taking up to first order in
$(q-1)$, we derive an analytical result for Tsallis distribution including
radial flow. Further, in the present work, we also study the speed of sound
($c_s$) as a function of temperature using the non-extensive Tsallis statistics
for different $q$ values and for different mass cut-offs.


title: Indication of Differential Kinetic Freeze-out at RHIC and LHC Energies

abstract:
  The transverse momentum spectra at RHIC and LHC for A+A and p+p collisions
are studied with Tsallis distributions in different approaches i.e. with and
without radial flow. The information on the freeze-out surface in terms of
freeze-out volume, temperature, chemical potential and radial flow velocities
for different particle species are obtained. These parameters are found to show
a systematic behavior with mass dependence. It is observed that the heavier
particles freeze-out early as compared to lighter particles and freeze-out
surfaces are different for different particles, which is a direct signature of
mass dependent differential freeze-out. Further, we observe that the radial
flow velocity decreases with increasing mass. This confirms the mass ordering
behavior in collectivity observed in heavy-ion collisions. It is also observed
that the systems created in peripheral heavy-ion collisions and in
proton-proton collisions are of similar thermodynamic nature.


title: Representable posets

abstract:
  A poset is representable if it can be embedded in a field of sets in such a
way that existing finite meets and joins become intersections and unions
respectively (we say finite meets and joins are preserved). More generally, for
cardinals $\alpha$ and $\beta$ a poset is said to be
$(\alpha,\beta)$-representable if an embedding into a field of sets exists that
preserves meets of sets smaller than $\alpha$ and joins of sets smaller than
$\beta$. We show using an ultraproduct/ultraroot argument that when
$2\leq\alpha,\beta\leq \omega$ the class of $(\alpha,\beta)$-representable
posets is elementary, but does not have a finite axiomatization in the case
where either $\alpha$ or $\beta=\omega$. We also show that the classes of
posets with representations preserving either countable or all meets and joins
are pseudoelementary.


title:
Single Crystal Growth of the New Pressure-induced-superconductor CrAs
  via Chemical Vapor Transport

abstract:
  Mono-arsenide CrAs, endures a helical anti-ferromagnetic order transition at~
265 K under ambient pressure. Recently, pressure-induced-superconductivity was
discovered vicinity to the helical anti-ferromagnetic order in CrAs[Wei Wu et
al., Nature Communications 5, 5508 (2014).]. However, the size of crystal grown
via tin flux method is as small as 1 mm in longest dimension. In this work, we
report the single crystal growth of CrAs with size of 1 * 5 * 1 mm3 via
chemical vapor transport method and its physical properties.


title:
A novel approach to the discovery of ternary BBP-type formulas for
  polylogarithm constants

abstract:
  Using a clear and straightforward approach, we prove new ternary (base 3)
digit extraction BBP-type formulas for polylogarithm constants. Some known
results are also rediscovered in a more direct and elegant manner. A previously
unproved degree~4 ternary formula is also proved. Finally, a couple of ternary
zero relations are established, which prove two known but hitherto unproved
formulas.


title:
Existence and BV-regularity for Neutron transport equation in non-convex
  domain

abstract:
  This paper considers the neutron transport equation in bounded domain with a
combination of the diffusive boundary condition and the in-flow boundary
condition. We firstly study the existence of solution in any fixed time by
$L^2-L^{\infty}$ method, which was established to study Boltzmann equation in
\cite{[Guo2]}. Based on the uniform estimates of the solution, we also consider
the BV-regularity of the solution in non-convex domain. A cut-off function,
which aims to exclude all the characteristics emanating from the grazing set
$\mathfrak{S}_B$, has been constructed precisely.


title:
Particle basis of Feigin-Stoyanovsky's type subspaces of level $1$
  $\tilde{\mathfrak{sl}}_{\ell+1}(\mathbb{C})$-modules

abstract:
  We construct particle basis for Feigin-Stoyanovsky's type subspaces of level
$1$ standard $\tilde{\mathfrak{sl}}_{\ell+1}(\mathbb{C})$-modules. From the
description we obtain character formulas.


title: On the Sign Changes of a Weighted Divisor Problem

abstract:
  Let $S\big(x; \frac{a_1}{q_1}, \frac{a_2}{q_2}\big)=\mathop{{\sum}'}_{mn\leq
x} \cos\big(2\pi m\frac{a_1}{q_1}\big)\sin\big(2\pi n\frac{a_2}{q_2}\big)$ with
$x\geq q_1q_2, 1\leq a_i\leq q_i$, and $(a_i, q_i)=1$ ($i=1, 2$). We study the
sign changes of $S\big(x; \frac{a_1}{q_1}, \frac{a_2}{q_2}\big)$, and prove
that for a sufficiently large constant $C$, $S\big(x; \frac{a_1}{q_1},
\frac{a_2}{q_2}\big)$ changes sign in the interval $[T,T+C\sqrt{T}]$ for any
large $T$. Meanwhile, we show that for a small constant $c'$, there exist
infinitely many subintervals of length $c'\sqrt{T}\log^{-7}T$ in $[T,2T]$ where
$\pm S\big(t; \frac{a_1}{q_1}, \frac{a_2}{q_2}\big)> c_5
(q_1q_2)^\frac{3}{4}t^\frac{1}{4}$ always holds.


title:
Very ampleness of the bicanonical line bundle on compact complex two
  ball quotients

abstract:
  The purpose of this note is to show that $2K$ of any smooth compact complex
two ball quotient is very ample, except possibly for four pairs of fake
projective planes of minimal type, where $K$ is the canonical line bundle. For
the four pairs of fake projective planes, sections of $2K_M$ give an embedding
of $M$ except possibly for at most two points on $M$.


title: Guitar Solos as Networks

abstract:
  This paper presents an approach to model melodies (and music pieces in
general) as networks. Notes of a melody can be seen as nodes of a network that
are connected whenever these are played in sequence. This creates a directed
graph. By using complex network theory, it is possible to extract some main
metrics, typical of networks, that characterize the piece. Using this
framework, we provide an analysis on a set of guitar solos performed by main
musicians. The results of this study indicate that this model can have an
impact on multimedia applications such as music classification, identification,
and automatic music generation.


title:
Enhancing the detection probability of single waveguided-photon by
  cavity technique

abstract:
  The resonant-cavity-enhanced (RCE) technique is an important approach to
increasing the detection efficiency (DE) of typical free-space coupling
photons. Here, we show that such a technique can also be utilized to increase
the detection probability (DP) of a single waveguide-coupled photon. Based on a
fully quantum mechanical theory in real space, we exactly calculated the
absorption probability of a single photon for a two-level detector next to the
waveguide. We find that the DP of the waveguide photon for the detector in a
waveguide-coupled ring cavity is significantly higher than that for the bare
detector directly coupled to the photon. Physically, the DP of the photon for
the bare detector next to the waveguide is always limited by the finite
transmission and reflection probabilities of the photon. The cavity technique
is used to store the photon and thus increase its DP. The feasibility of the
proposal with current integrated optical devices is then discussed.


title:
An Approximate Dynamic Programming Approach to Adversarial Online
  Learning

abstract:
  We describe an approximate dynamic programming (ADP) approach to compute
approximations of the optimal strategies and of the minimal losses that can be
guaranteed in discounted repeated games with vector-valued losses. Such games
prominently arise in the analysis of regret in repeated decision-making in
adversarial environments, also known as adversarial online learning. At the
core of our approach is a characterization of the lower Pareto frontier of the
set of expected losses that a player can guarantee in these games as the unique
fixed point of a set-valued dynamic programming operator. When applied to the
problem of regret minimization with discounted losses, our approach yields
algorithms that achieve markedly improved performance bounds compared to
off-the-shelf online learning algorithms like Hedge. These results thus suggest
the significant potential of ADP-based approaches in adversarial online
learning.


title:
An Integrated Spectrum and Information Market for Green Cognitive
  Communications

abstract:
  A database-assisted TV white space network can achieve the goal of green
cognitive communication by effectively reducing the energy consumption in
cognitive communications. The success of such a novel network relies on a
proper business model that provides incentives for all parties involved. In
this paper, we propose an integrated spectrum and information market for a
database-assisted TV white space network, where the geo-location database
serves as both the spectrum market platform and the information market
platform. We study the interactions among the database, the spectrum licensee,
and unlicensed users by modelling the system as a three-stage sequential
decision process. In Stage I, the database and the licensee negotiate regarding
the commission for the licensee to use the spectrum market platform. In Stage
II, the database and the licensee compete for selling information or channels
to unlicensed users. In Stage III, unlicensed users determine whether they
should buy exclusive usage right of licensed channels from the licensee or
information regarding unlicensed channels from the database. Analyzing such a
three-stage model is challenging due to the co-existence of both positive and
negative network externalities in the information market. Despite of this, we
are able to characterize how the network externalities affect the equilibrium
behaviors of all parties involved. We analytically show that in this integrated
market, the licensee can never get a market share more than half. Our numerical
results further show that the proposed integrated market can improve the
network profit up to 87%, compared with a pure information market.


title:
Microscopic flows of suspensions of the green non-motile Chlorella
  micro-alga at various volume fractions: applications to intensified photo bio
  reactors

abstract:
  An experimental study of flows of the green non-motile Chlorella micro-alga
in a plane microchannel is presented. Depending on the value of the cell volume
fraction, three distinct flow regimes are observed. For low values of the cell
volume fraction a Newtonian flow regime characterised by a Poiseuille like flow
field, absence of wall slip and hydrodynamic reversibility of the flow states
is observed. For intermediate values of the cell volume fraction, the flow
profiles are consistent with a Poiseuille flow of a shear thinning fluid in the
presence of slip at the channel's wall. For even larger cell volume fractions,
a yield stress like behaviour manifested through the presence of a central
solid plug is observed. Except for the Newtonian flow regime, a strong
hydrodynamic irreversibility of the flow and wall slip are found. The
calculation of the wall shear rate and wall stress based on the measured flow
fields allows one to identify the mechanisms of wall slip observed in the shear
thinning and yield stress regimes.


title:
Cutting Feynman Loops in Ultrastrong Cavity QED: Stimulated Emission and
  Reabsorption of Virtual Particles Dressing a Physical Excitation

abstract:
  In quantum field theory, bare particles are dressed by a cloud of virtual
particles to form physical particles. The virtual particles affect properties
such as the mass and charge of the physical particles, and it is only these
modified properties that can be measured in experiments, not the properties of
the bare particles. The influence of virtual particles is prominent in the
ultrastrong-coupling regime of cavity quantum electrodynamics (QED), which has
recently been realized in several condensed-matter systems. In some of these
systems, the effective interaction between atom-like transitions and the cavity
photons can be switched on or off by external control pulses. This offers
unprecedented possibilities for exploring quantum vacuum fluctuations and the
relation between physical and bare particles. Here we show that, by applying
external electromagnetic pulses of suitable amplitude and frequency, each
virtual photon dressing a physical excitation in cavity-QED systems can be
converted into a physical observable photon, and back again. In this way, the
hidden relationship between the bare and the physical excitations becomes
experimentally testable. The conversion between virtual and physical photons
can be clearly pictured using Feynman diagrams with cut loops.


title: Decomposable Leavitt path algebras for arbitrary graphs

abstract:
  For any field $K$ and for a completely arbitrary graph $E$, we characterize
the Leavitt path algebras $L_K(E)$ that are indecomposable (as a direct sum of
two-sided ideals) in terms of the underlying graph. When the algebra
decomposes, it actually does so as a direct sum of Leavitt path algebras for
some suitable graphs. Under certain finiteness conditions, a unique
indecomposable decomposition exists.


title:
Electron dichotomy on the SrTiO$_3$ defect surface augmented by
  many-body effects

abstract:
  In a common paradigm, the electronic structure of condensed matter is divided
into weakly and strongly correlated compounds. While conventional band theory
usually works well for the former class, many-body effects are essential for
the latter. Materials like the familiar SrTiO$_3$ compound that bridge or even
abandon this characterization scheme are highly interesting. Here it is shown
by means of combining density functional theory with dynamical-mean field
theory that oxygen vacancies on the STO (001) surface give rise to a dichotomy
of weakly-correlated $t_{2g}$ low-energy quasiparticles and localized 'in-gap'
states of dominant $e_g$ character with subtle correlation signature. We
furthermore touch base with recent experimental work and study the surface
instability towards magnetic order.


title:
Growth rates of 3-dimensional hyperbolic Coxeter groups are Perron
  numbers

abstract:
  In this paper we consider the growth rates of 3-dimensional hyperbolic
Coxeter polyhedra some of its dihedral angles are $\frac{\pi}{m}$ for
$m\geq{7}$. By combining with the classical result by Parry \cite{Pa} and the
main result of \cite{Y}, we prove that the growth rates of 3-dimensional
hyperbolic Coxeter groups are Perron numbers.


title:
Observational evidence for the evolution of nuclear metallicity and star
  formation rate as the merger stage

abstract:
  We investigate the evolution of nuclear gas-phase oxygen abundance and star
formation rate (SFR) of local far-infrared selected star-forming galaxies along
the merger sequence, as traced by their optical morphologies. The sample was
drawn from a cross-correlation analysis of the IRAS Point Source Catalog
Redshift Survey and 1 Jy ultraluminous infrared galaxies sample with the Sloan
Digital Sky Survey Data Release 7 database. The investigation is done by
comparing our sample to a control sample matched in the normalized redshift
distribution in two diagnostics, which are the nuclear gas-phase metallicity
vs. stellar mass and the nuclear SFR vs. stellar mass diagrams. Galaxies with
different morphological types show different mass-metallicity relations (MZR).
Compared to the MZR defined by the control sample, isolated spirals have
comparable metallicities with the control sample at a given stellar mass.
Spirals in pairs and interacting galaxies with projected separations $r_{p} >$
20 kpc show mild metallicity dilution of 0.02-0.03 dex. Interacting galaxies
with $r_{p} <$ 20 kpc, pre-mergers and advanced mergers are under-abundant by
~0.06, ~0.05 and ~0.04 dex, respectively. This shows an evolutionary trend that
the metallicity is increasingly depressed as the merging proceeds and it is
diluted most dramatically when two galaxies are closely interacting.
Afterwards, the interstellar medium (ISM) is enriched when the galaxies
coalesce. This is the first time that such ISM enrichment at the final
coalescence stage is observed, which demonstrates the importance of supernova
explosion in affecting the nuclear metallicity. Meanwhile the central SFR
enhancement relative to the control sample evolves simultaneously with the
nuclear gas-phase oxygen abundance. Our results support the predictions from
numerical simulations.


title: Scaled stochastic gradient descent for low-rank matrix completion

abstract:
  The paper looks at a scaled variant of the stochastic gradient descent
algorithm for the matrix completion problem. Specifically, we propose a novel
matrix-scaling of the partial derivatives that acts as an efficient
preconditioning for the standard stochastic gradient descent algorithm. This
proposed matrix-scaling provides a trade-off between local and global second
order information. It also resolves the issue of scale invariance that exists
in matrix factorization models. The overall computational complexity is linear
with the number of known entries, thereby extending to a large-scale setup.
Numerical comparisons show that the proposed algorithm competes favorably with
state-of-the-art algorithms on various different benchmarks.


title:
TapDrag: An Alternative Dragging Technique on Medium-Sized MultiTouch
  Displays Reducing Skin Irritation and Arm Fatigue

abstract:
  Medium-sized touch displays, sized 30 to 50 inches, are becoming more
affordable and more widely available. Prolonged use of such displays can result
in arm fatigue or skin irritation, especially when multiple long distance drags
are involved. To address this issue, we present TapDrag, an alternative
dragging technique that complements traditional dragging with a simple tapping
gesture on both ends of the intended dragging path. Our experimental evaluation
suggests that TapDrag is a viable alternative to traditional dragging with
faster task completion times for long distances. Qualitative user feedback
indicates that TapDrag helps prevent skin irritation. A reduction in arm
fatigue remains unconfirmed.


title: Embedding in factorisable restriction monoids

abstract:
  Each restriction semigroup is proved to be embeddable in a factorisable
restriction monoid, or, equivalently, in an almost factorisable restriction
semigroup. It is also established that each restriction semigroup has a proper
cover which is embeddable in a semidirect product of a semilattice by a group.


title:
Unsupervised CNN for Single View Depth Estimation: Geometry to the
  Rescue

abstract:
  A significant weakness of most current deep Convolutional Neural Networks is
the need to train them using vast amounts of manu- ally labelled data. In this
work we propose a unsupervised framework to learn a deep convolutional neural
network for single view depth predic- tion, without requiring a pre-training
stage or annotated ground truth depths. We achieve this by training the network
in a manner analogous to an autoencoder. At training time we consider a pair of
images, source and target, with small, known camera motion between the two such
as a stereo pair. We train the convolutional encoder for the task of predicting
the depth map for the source image. To do so, we explicitly generate an inverse
warp of the target image using the predicted depth and known inter-view
displacement, to reconstruct the source image; the photomet- ric error in the
reconstruction is the reconstruction loss for the encoder. The acquisition of
this training data is considerably simpler than for equivalent systems,
requiring no manual annotation, nor calibration of depth sensor to camera. We
show that our network trained on less than half of the KITTI dataset (without
any further augmentation) gives com- parable performance to that of the state
of art supervised methods for single view depth estimation.


title:
Physics of leptoquarks in precision experiments and at particle
  colliders

abstract:
  We present a comprehensive review of physics effects generated by leptoquarks
(LQs), i.e., hypothetical particles that can turn quarks into leptons and vice
versa, of either scalar or vector nature. These considerations include
discussion of possible completions of the Standard Model that contain LQ
fields. The main focus of the review is on those LQ scenarios that are not
problematic with regard to proton stability. We accordingly concentrate on the
phenomenology of light leptoquarks that is relevant for precision experiments
and particle colliders. Important constraints on LQ interactions with matter
are derived from precision low-energy observables such as electric dipole
moments, (g-2) of charged leptons, atomic parity violation, neutral meson
mixing, Kaon, B, and D meson decays, etc. We provide a general analysis of
indirect constraints on the strength of LQ interactions with the quarks and
leptons to make statements that are as model independent as possible. We
address complementary constraints that originate from electroweak precision
measurements, top, and Higgs physics. The Higgs physics analysis we present
covers not only the most recent but also expected results from the Large Hadron
Collider (LHC). We finally discuss direct LQ searches. Current experimental
situation is summarized and self-consistency of assumptions that go into
existing accelerator-based searches is discussed. A progress in making
next-to-leading order predictions for both pair and single LQ productions at
colliders is also outlined.