title: High-mass star formation toward southern infrared bubble S10

abstract:
  An investigation in radio and infrared wavelengths of two high-mass star
forming regions toward the southern Galactic bubble S10 is presented here. The
two regions under study are associated with the broken bubble S10 and Extended
Green Object, G345.99-0.02, respectively. Radio continuum emission mapped at
610 and 1280 MHz using the Giant Metrewave Radio Telescope, India is detected
towards both the regions. These regions are estimated to be ionized by early B
to late O type stars. Spitzer GLIMPSE mid-infrared data is used to identify
young stellar objects associated with these regions. A Class I/II type source,
with an estimated mass of 6.2 M{\sun} , lies {\sim} 7{\arcsec} from the radio
peak. Pixel-wise, modified blackbody fits to the thermal dust emission using
Herschel far-infrared data is performed to construct dust temperature and
column density maps. Eight clumps are detected in the two regions using the 250
{\mu}m image. The masses and linear diameter of these range between {\sim} 300
- 1600 M{\sun} and 0.2 - 1.1 pc, respectively which qualifies them as high-mass
star forming clumps. Modelling of the spectral energy distribution of these
clumps indicates the presence of high luminosity, high accretion rate, massive
young stellar objects possibly in the accelerating accretion phase. Further,
based on the radio and MIR morphology, the occurrence of a possible bow-wave
towards the likely ionizing star is explored.


title:
Upper and Lower Critical Decay Exponents of Ising Ferromagnets with
  Long-range Interaction

abstract:
  We investigate the universality class of the finite-temperature phase
transition of the two-dimensional Ising model with the algebraically decaying
ferromagnetic long-range interaction, $J_{ij} = |\vec{r}_i
-\vec{r}_j|^{-(d+\sigma)}$, where $d$ (=2) is the dimension of the system and
$\sigma$ the decay exponent, by means of the order-$N$ cluster-algorithm Monte
Carlo method. In particular, we focus on the upper and lower critical decay
exponents, the boundaries between the mean-field-universality, intermediate,
and short-range-universality regimes. At the critical decay exponents, it is
found that the critical amplitude of the standard Binder ratio of magnetization
exhibits the extremely slow convergence as a function of the system size. We
propose more effective physical quantities, the combined Binder ratio and the
self-combined Binder ratio, both of which cancel the leading finite-size
corrections of the conventional Binder ratio. Utilizing these techniques, we
clearly demonstrate that in two dimensions the lower and upper critical decay
exponents are $\sigma = 1$ and 7/4, respectively, contrary to the recent Monte
Carlo and the renormalization-group studies [M. Picco, arXiv:1207.1018; T.
Blanchard, et al., Europhys. Lett. 101, 56003 (2013)].


title: Interdependent Scheduling Games

abstract:
  We propose a model of interdependent scheduling games in which each player
controls a set of services that they schedule independently. A player is free
to schedule his own services at any time; however, each of these services only
begins to accrue reward for the player when all predecessor services, which may
or may not be controlled by the same player, have been activated. This model,
where players have interdependent services, is motivated by the problems faced
in planning and coordinating large-scale infrastructures, e.g., restoring
electricity and gas to residents after a natural disaster or providing medical
care in a crisis when different agencies are responsible for the delivery of
staff, equipment, and medicine. We undertake a game-theoretic analysis of this
setting and in particular consider the issues of welfare maximization,
computing best responses, Nash dynamics, and existence and computation of Nash
equilibria.


title: Spin-Orbit Torques in ferrimagnetic GdFeCo Alloys

abstract:
  The spin-orbit torque switching of ferrimagnetic
Gd$_x$(Fe$_{90}$Co$_{10}$)$_{100-x}$ films was studied for both transition
metal (TM)-rich and rare earth (RE)-rich configurations. The spin-orbit torque
driven magnetization switching follows the same handedness in TM-rich and
RE-rich samples with respect to the total magnetization, but the handedness of
the switching is reversed with respect to the TM magnetization. This indicates
that the sign of the spin-orbit-torque-driven magnetic switching follows the
total magnetization, although transport based techniques such as anomalous Hall
effect are only sensitive to the transition metal magnetization. These results
provide important insight into the physics of spin angular momentum transfer in
materials with antiferromagnetically coupled sublattices.


title: Extreme Stochastic Variational Inference: Distributed and Asynchronous

abstract:
  Stochastic variational inference (SVI), the state-of-the-art algorithm for
scaling variational inference to large-datasets, is inherently serial.
Moreover, it requires the parameters to fit in the memory of a single
processor; this is problematic when the number of parameters is in billions. In
this paper, we propose extreme stochastic variational inference (ESVI), an
asynchronous and lock-free algorithm to perform variational inference for
mixture models on massive real world datasets. ESVI overcomes the limitations
of SVI by requiring that each processor only access a subset of the data and a
subset of the parameters, thus providing data and model parallelism
simultaneously. We demonstrate the effectiveness of ESVI by running Latent
Dirichlet Allocation (LDA) on UMBC-3B, a dataset that has a vocabulary of 3
million and a token size of 3 billion. In our experiments, we found that ESVI
not only outperforms VI and SVI in wallclock-time, but also achieves a better
quality solution. In addition, we propose a strategy to speed up computation
and save memory when fitting large number of topics.


title: Invariant differential operators in positive characteristic

abstract:
  We consider an analog of the problem Veblen formulated in 1928 at the IMC:
classify invariant differential operators between "natural objects" (spaces of
either tensor fields, or jets, in modern terms) over a real manifold of any
dimension. For unary operators, the problem was solved by Rudakov (no nonscalar
operators except the exterior differential); for binary ones, by Grozman (there
are no operators of orders higher than 3, operators of order 2 and 3 are, bar
an exception in dimension 1, compositions of order 1 operators which, up to
dualization and permutation of arguments, form 8 families). In dimension one,
Grozman discovered an indecomposable selfdual operator of order 3 that does not
exist in higher dimensions. We solve Veblen's problem in the 1-dimensional case
over the ground field of positive characteristic. In addition to analogs of the
Berezin integral (strangely overlooked so far) and binary operators constructed
from them, we discovered two more (up to dualization) types of indecomposable
operators of however high order: analogs of the Grozman operator and a
completely new type of operators.


title: Edge Solitons in Nonlinear Photonic Topological Insulators

abstract:
  We show theoretically that a photonic topological insulator can support edge
solitons that are strongly self-localized and propagate unidirectionally along
the lattice edge. The photonic topological insulator consists of a Floquet
lattice of coupled helical waveguides, in a medium with local Kerr
nonlinearity. The soliton behavior is strongly affected by the topological
phase of the linear lattice. The topologically nontrivial phase gives a
continuous family of solitons, while the topologically trivial phase gives an
embedded soliton that occurs at a single power, and arises from a self-induced
local nonlinear shift in the inter-site coupling. The solitons can be used for
nonlinear switching and logical operations, functionalities that have not yet
been explored in topological photonics. We demonstrate using solitons to
perform selective filtering via propagation through a narrow channel, and using
soliton collisions for optical switching.


title: First interpretation of 13 TeV supersymmetry searches in the pMSSM

abstract:
  The combined constraints from six early Run 2 ATLAS searches for
supersymmetry are interpreted in the phenomenological minimal supersymmetric
extension to the Standard Model (pMSSM). Each of the searches was based on
proton-proton collision data recorded in 2015 at $\sqrt{s} =13$ TeV with 3.2
fb$^{-1}$ of integrated luminosity. Sensitivity to squarks of the first two
generations and gluinos are evaluated using fast detector simulation. Results
are presented in the 19-parameter R-parity conserving pMSSM with the lightest
supersymmetric particle (LSP) being the neutralino. Considering 181.8k points
that survived Run 1 constraints, 15.7% are excluded at 95% confidence level. Of
those satisfying these Run 2 constraints, 0.5% (1.0%) have sub-TeV gluinos
(sub-500 GeV squarks), the lightest of which has a mass of 757 GeV (293 GeV)
with a 689 GeV (217 GeV) LSP.


title: Inverse problem for time-series valued computer model via scalarization

abstract:
  For an expensive to evaluate computer simulator, even the estimate of the
overall surface can be a challenging problem. In this paper, we focus on the
estimation of the inverse solution, i.e., to find the set(s) of input
combinations of the simulator that generates (or gives good approximation of) a
pre-determined simulator output. Ranjan et al. (2008) proposed an expected
improvement criterion under a sequential design framework for the inverse
problem with a scalar valued simulator. In this paper, we focus on the inverse
problem for a time-series valued simulator. We have used a few simulated and
two real examples for performance comparison.


title:
The Distance and Properties of Hydrogen Clouds in the Leading Arm of the
  Magellanic System

abstract:
  We present a high-resolution study of five high-velocity clouds in the
Magellanic Leading Arm region. This is a follow-up study of our widefield
Parkes survey of the region in order to probe the multiphase structures of the
clouds and to give an insight to their origin, evolution and distance.
High-resolution data were obtained from the Australia Telescope Compact Array.
By combining with single-dish data from the Galactic All-Sky Survey (GASS), we
are able to probe compact and diffuse emission simultaneously. We identify
resolved and unresolved clumps. Physical parameters were derived for both
diffuse structure and compact clumps. The latter are cold with typical velocity
linewidths of 5 km/s. We find a gradient in thermal halo pressure, hydrogen
density and HI column density of HVC as a function of Galactic latitude. This
is possibly the first observational evidence of varying distance in the Leading
Arm region, with the leading part of the Leading Arm (LA II and III) probably
being closer to the Galactic disc than the trailing end (LA I).


title:
Psychologically based Virtual-Suspect for Interrogative Interview
  Training

abstract:
  In this paper, we present a Virtual-Suspect system which can be used to train
inexperienced law enforcement personnel in interrogation strategies. The system
supports different scenario configurations based on historical data. The
responses presented by the Virtual-Suspect are selected based on the
psychological state of the suspect, which can be configured as well.
Furthermore, each interrogator's statement affects the Virtual-Suspect's
current psychological state, which may lead the interrogation in different
directions. In addition, the model takes into account the context in which the
statements are made. Experiments with 24 subjects demonstrate that the
Virtual-Suspect's behavior is similar to that of a human who plays the role of
the suspect.


title:
Chaos in the motion of a test scalar particle coupling to Einstein
  tensor in Schwarzschild-Melvin black hole spacetime

abstract:
  We present firstly the equation of motion for a test scalar particle coupling
to Einstein tensor in the Schwarzschild-Melvin black hole spacetime through the
short-wave approximation. Through analysing Poincar\'{e} sections, the power
spectrum, the fast Lyapunov exponent indicator and the bifurcation diagram, we
investigate the effects of coupling parameter on the chaotic behavior of the
particles. With the increase of the coupling strength, we find that the motion
of coupled particle for the chosen parameters becomes more regular and order
for the negative couple constant. While, for the positive one, the motion of
coupled particles first undergoes a series of transitions between chaotic
motion and regular motion and then falls into horizon or escapes to spatial
infinite. Our results show that the coupling brings about richer effects for
the motion of the particles.


title:
Deep convolutional neural networks for predominant instrument
  recognition in polyphonic music

abstract:
  Identifying musical instruments in polyphonic music recordings is a
challenging but important problem in the field of music information retrieval.
It enables music search by instrument, helps recognize musical genres, or can
make music transcription easier and more accurate. In this paper, we present a
convolutional neural network framework for predominant instrument recognition
in real-world polyphonic music. We train our network from fixed-length music
excerpts with a single-labeled predominant instrument and estimate an arbitrary
number of predominant instruments from an audio signal with a variable length.
To obtain the audio-excerpt-wise result, we aggregate multiple outputs from
sliding windows over the test audio. In doing so, we investigated two different
aggregation methods: one takes the average for each instrument and the other
takes the instrument-wise sum followed by normalization. In addition, we
conducted extensive experiments on several important factors that affect the
performance, including analysis window size, identification threshold, and
activation functions for neural networks to find the optimal set of parameters.
Using a dataset of 10k audio excerpts from 11 instruments for evaluation, we
found that convolutional neural networks are more robust than conventional
methods that exploit spectral features and source separation with support
vector machines. Experimental results showed that the proposed convolutional
network architecture obtained an F1 measure of 0.602 for micro and 0.503 for
macro, respectively, achieving 19.6% and 16.4% in performance improvement
compared with other state-of-the-art algorithms.


title: Small Values of Coefficients of a Half Lerch Sum

abstract:
  Andrews, Dyson and Hickerson proved many interesting properties of
coefficients for a Ramanujan's $q$-hypergeometric series by relating it to real
quadratic field $\Q(\sqrt{6})$ and using the arithmetic of $\Q(\sqrt{6})$,
hence solved a conjecture of Andrews on the distributions of its Fourier
coefficients. Motivated by Andrews's conjecture, we discuss an interesting
$q$-hypergeometric series which comes from a Lerch sum and rank and crank
moments for partitions and overpartitions. We give Andrews-like conjectures for
its coefficients. We obtain partial results on the distributions of small
values of its coefficients toward these conjectures.


title:
Fixed-time consensus of multiple double-integrator systems under
  directed topologies: A motion-planning approach

abstract:
  This paper investigates the fixed-time consensus problem under directed
topologies. By using a motion-planning approach, a class of distributed
fixed-time algorithms are developed for a multi-agent system with
double-integrator dynamics. In the context of the fixed-time consensus, we
focus on both directed fixed and switching topologies. Under the directed fixed
topology, a novel class of distributed algorithms are designed, which guarantee
the consensus of the multi-agent system with a fixed settling time if the
topology has a directed spanning tree. Under the directed periodically
switching topologies, the fixedtime consensus is solved via the proposed
algorithms if the topologies jointly have a directed spanning tree. In
particular, the fixed settling time can be off-line pre-assigned according to
task requirements. Compared with the existing results, to our best knowledge,
it is the first time to solve the fixed-time consensus problem for
double-integrator systems under directed topologies. Finally, a numerical
example is given to illustrate the effectiveness of the analytical results.


title: Note About Unstable D-Brane with Dynamical Tension

abstract:
  We propose an action for unstable Dp-brane with dynamical tension. We show
that the equations of motion are equivalent to the equations of motion derived
from DBI and WZ actions for non-BPS Dp-brane. We also find Hamiltonian
formulation of this action and analyze properties of the solutions
corresponding to the tachyon vacuum and zero tension solution.


title: The Natural Selection of Bad Science

abstract:
  Poor research design and data analysis encourage false-positive findings.
Such poor methods persist despite perennial calls for improvement, suggesting
that they result from something more than just misunderstanding. The
persistence of poor methods results partly from incentives that favor them,
leading to the natural selection of bad science. This dynamic requires no
conscious strategizing---no deliberate cheating nor loafing---by scientists,
only that publication is a principle factor for career advancement. Some
normative methods of analysis have almost certainly been selected to further
publication instead of discovery. In order to improve the culture of science, a
shift must be made away from correcting misunderstandings and towards rewarding
understanding. We support this argument with empirical evidence and
computational modeling. We first present a 60-year meta-analysis of statistical
power in the behavioral sciences and show that power has not improved despite
repeated demonstrations of the necessity of increasing power. To demonstrate
the logical consequences of structural incentives, we then present a dynamic
model of scientific communities in which competing laboratories investigate
novel or previously published hypotheses using culturally transmitted research
methods. As in the real world, successful labs produce more "progeny", such
that their methods are more often copied and their students are more likely to
start labs of their own. Selection for high output leads to poorer methods and
increasingly high false discovery rates. We additionally show that replication
slows but does not stop the process of methodological deterioration. Improving
the quality of research requires change at the institutional level.


title:
Self-assembled chiral phosphorus nanotubes from phosphorene: a molecular
  dynamics study

abstract:
  Controlled syntheses in nanoscale structures should be expected and
phosphorous nanotubes with predefined chiralities are important in electronic
devices with tunable bandgap. Here, incorporating molecular dynamics
simulations with theoretical analyses, we show that a zigzag phosphorene
nanoribbon can self-assemble and form a corresponding chiral phosphorous
nanotube surrounding a template armchair phosphorous nanotube. The van der
Waals potential between the nanoribbon and the nanotube is transformed to the
intrinsic deformed and chemical bonding energies of the synthesized tube
together with partial kinetic energy. The self-assembly process has an apparent
temperature dependence and size effect and the formed chiral tube is
thermodynamically stable. Also, the chirality and measurement can be tuned by
the radius of template tube and the aspect ratio of raw ribbon. The study
suggests a novel and feasible approach for controlled synthesis of phosphorous
nanotubes and thus is of great interest for semiconductor device applications.


title: Evaluating Distributed Execution of Workloads

abstract:
  Resource selection and task placement for distributed execution poses
conceptual and implementation difficulties. Although resource selection and
task placement are at the core of many tools and workflow systems, the methods
are ad hoc rather than being based on models. Consequently, partial and
non-interoperable implementations proliferate. We address both the conceptual
and implementation difficulties by experimentally characterizing diverse
modalities of resource selection and task placement. We compare the
architectures and capabilities of two systems: the AIMES middleware and Swift
workflow scripting language and runtime. We integrate these systems to enable
the distributed execution of Swift workflows on Pilot-Jobs managed by the AIMES
middleware. Our experiments characterize and compare alternative execution
strategies by measuring the time to completion of heterogeneous uncoupled
workloads executed at diverse scale and on multiple resources. We measure the
adverse effects of pilot fragmentation and early binding of tasks to resources
and the benefits of backfill scheduling across pilots on multiple resources. We
then use this insight to execute a multi-stage workflow across five
production-grade resources. We discuss the importance and implications for
other tools and workflow systems.


title: Full-Sun observations for identifying the source of the slow solar wind

abstract:
  Fast (>700 km/s) and slow (~400 km/s) winds stream from the Sun, permeate the
heliosphere and influence the near-Earth environment. While the fast wind is
known to emanate primarily from polar coronal holes, the source of the slow
wind remains unknown. Here we identify possible sites of origin using a slow
solar wind source map of the entire Sun, which we construct from specially
designed, full- disk observations from the Hinode satellite, and a magnetic
field model. Our map provides a full-Sun observation that combines three key
ingredients for identifying the sources: velocity, plasma composition and
magnetic topology and shows them as solar wind composition plasma outflowing on
open magnetic field lines. The area coverage of the identified sources is large
enough that the sum of their mass contributions can explain a significant
fraction of the mass loss rate of the solar wind.


title: Efficiency of research performance and the glass researcher

abstract:
  Abramo and D'Angelo (in press) doubt the validity of established
size-independent indicators measuring citation impact and plead in favor of
measuring scientific efficiency (by using the Fractional Scientific Strength
indicator). This note is intended to comment on some questionable and a few
favorable approaches in the paper by Abramo and D'Angelo (in press).


title: Counting in One-Hop Beeping Networks

abstract:
  We consider networks of processes which interact with beeps. In the basic
model defined by Cornejo and Kuhn, which we refer to as the $BL$ variant,
processes can choose in each round either to beep or to listen. Those who beep
are unable to detect simultaneous beeps. Those who listen can only distinguish
between silence and the presence of at least one beep. Beeping models are weak
in essence and even simple tasks may become difficult or unfeasible with them.
  In this paper, we address the problem of computing how many participants
there are in a one-hop network: the {\em counting} problem. We first observe
that no algorithm can compute this number with certainty in $BL$, whether the
algorithm be deterministic or even randomised (Las Vegas). We thus consider the
stronger variant where beeping nodes are able to detect simultaneous beeps,
referred to as $B_{cd}L$ (for {\em collision detection}). We prove that at
least $n$ rounds are necessary in $B_{cd}L$, and we present an algorithm whose
running time is $O(n)$ rounds with high probability. Further experimental
results show that its expected running time is less than $10n$. Finally, we
discuss how this algorithm can be adapted in other beeping models. In
particular, we show that it can be emulated in $BL$, at the cost of a
logarithmic slowdown and of trading its Las Vegas nature (result certain, time
uncertain) against Monte Carlo (time certain, result uncertain).


title: Functorial Test Modules

abstract:
  In this article we introduce a slight modification of the definition of test
modules which is an additive functor $\tau$ on the category of coherent Cartier
modules. We show that in many situations this modification agrees with the
usual definition of test modules. Furthermore, we show that for a smooth
morphism $f \colon X \to Y$ of $F$-finite schemes one has a natural isomorphism
$f^! \circ \tau \cong \tau \circ f^!$. If $f$ is quasi-finite and of finite
type we construct a natural transformation $\tau \circ f_* \to f_* \circ \tau$.


title: A weakly universal cellular automaton on the tessellation $\{9,3\}$

abstract:
  In this paper, we construct a weakly universal cellular automaton on the
tessellation $\{9,3\}$ which has two states and which is not rotation invariant
but which is truly planar.


title: Optimal caching placement for wireless femto-caching network

abstract:
  This paper investigates optimal caching placement for wireless femto-caching
network. The average bit error rate (BER) is formulated as a function of
caching placement under wireless fading. To minimize the average BER, we
propose a greedy algorithm finding optimal caching placement with low
computational complexity. Exploiting the property of the optimal caching
placement which we derive, the proposed algorithm can be performed over
considerably reduced search space. Contrary to the optimal caching placement
without consideration of wireless fading aspects, we reveal that optimal
caching placement can be reached by balancing a tradeoff between two different
gains: file diversity gain and channel diversity gain. Moreover, we also
identify the conditions that the optimal placement can be found without running
the proposed greedy algorithm and derive the corresponding optimal caching
placement in closed form.


title: A Simpler Self-reduction Algorithm for Matroid Path-width

abstract:
  Path-width of matroids naturally generalizes the better known parameter of
path-width for graphs, and is NP-hard by a reduction from the graph case. While
the term matroid path-width was formally introduced by Geelen-Gerards-Whittle
[JCTB 2006] in pure matroid theory, it was soon recognized by Kashyap [SIDMA
2008] that it is the same concept as long-studied so called trellis complexity
in coding theory, later named trellis-width, and hence it is an interesting
notion also from the algorithmic perspective. It follows from a result of
Hlineny [JCTB 2006] that the decision problem, whether a given matroid over a
finite field has path-width at most t, is fixed-parameter tractable (FPT) in t,
but this result does not give any clue about constructing a path-decomposition.
The first constructive and rather complicated FPT algorithm for path-width of
matroids over a finite field was given by Jeong-Kim-Oum [SODA 2016]. Here we
propose a simpler "self-reduction" FPT algorithm for a path-decomposition.
Precisely, we design an efficient routine that constructs an optimal
path-decomposition of a matroid by calling any subroutine for testing whether
the path-width of a matroid is at most t (such as the aforementioned decision
algorithm for matroid path-width).


title: First results of CMS RPC performance at 13 TeV

abstract:
  The muon spectrometer of the CMS (Compact Muon Solenoid) experiment at the
Large Hadron Collider (LHC) is equipped with a redundant system made of
Resistive Plate Chambers (RPCs) and Drift Tube (DT) chambers in the barrel, RPC
and Cathode Strip Chambers (CSCs) in the endcap region. In this paper, the
first results of the performance of the RPC system during 2015 with the LHC
running at 13 TeV is presented. The stability of the RPC performance, in terms
of efficiency, cluster size and noise, is reported.


title: Kernel Mean Embedding of Distributions: A Review and Beyond

abstract:
  A Hilbert space embedding of a distribution---in short, a kernel mean
embedding---has recently emerged as a powerful tool for machine learning and
inference. The basic idea behind this framework is to map distributions into a
reproducing kernel Hilbert space (RKHS) in which the whole arsenal of kernel
methods can be extended to probability measures. It can be viewed as a
generalization of the original "feature map" common to support vector machines
(SVMs) and other kernel methods. While initially closely associated with the
latter, it has meanwhile found application in fields ranging from kernel
machines and probabilistic modeling to statistical inference, causal discovery,
and deep learning. The goal of this survey is to give a comprehensive review of
existing work and recent advances in this research area, and to discuss the
most challenging issues and open problems that could lead to new research
directions. The survey begins with a brief introduction to the RKHS and
positive definite kernels which forms the backbone of this survey, followed by
a thorough discussion of the Hilbert space embedding of marginal distributions,
theoretical guarantees, and a review of its applications. The embedding of
distributions enables us to apply RKHS methods to probability measures which
prompts a wide range of applications such as kernel two-sample testing,
independent testing, and learning on distributional data. Next, we discuss the
Hilbert space embedding for conditional distributions, give theoretical
insights, and review some applications. The conditional mean embedding enables
us to perform sum, product, and Bayes' rules---which are ubiquitous in
graphical model, probabilistic inference, and reinforcement learning---in a
non-parametric way. We then discuss relationships between this framework and
other related areas. Lastly, we give some suggestions on future research
directions.


title: On Equivalence of Matrices

abstract:
  A new matrix product, called the semi-tensor product (STP), is briefly
reviewed. The STP extends the classical matrix product to two arbitrary
matrices. Under STP the set of matrices becomes a monoid (semi-group with
identity). Some related structures and properties are investigated. Then the
generalized matrix addition is also introduced, which extends the classical
matrix addition to a class of two matrices with different dimensions.
  Motivated by STP of matrices, two kinds of equivalences of matrices
(including vectors) are introduced, which are called matrix equivalence
(M-equivalence) and vector equivalence (V-equivalence) respectively. The
lattice structure has been established for each equivalence. Under each
equivalence, the corresponding quotient space becomes a vector space. Under
M-equivalence, many algebraic, geometric, and analytic structures have been
posed to the quotient space, which include (i) lattice structure; (ii) inner
product and norm (distance); (iii) topology; (iv) a fiber bundle structure,
called the discrete bundle; (v) bundled differential manifold; (vi) bundled Lie
group and Lie algebra. Under V-equivalence, vectors of different dimensions
form a vector space ${\cal V}$, and a matrix $A$ of arbitrary dimension is
considered as an operator (linear mapping) on ${\cal V}$. When $A$ is a bounded
operator (not necessarily square but includes square matrices as a special
case), the generalized characteristic function, eigenvalue and eigenvector etc.
are defined.
  In one word, this new matrix theory overcomes the dimensional barrier in
certain sense. It provides much more freedom for using matrix approach to
practical problems.


title:
Links between the shock instability in core-collapse supernovae and
  asymmetric accretions of envelopes

abstract:
  The explosion mechanism of core-collapse supernovae has not been fully
understood yet but multi-dimensional fluid instabilities such as standing
accretion shock instability (SASI) and convection are now believed to be
crucial for shock revival. Another multi-dimensional effect that has been
recently argued is the asymmetric structures in progenitors, which are induced
by violent convections in silicon/oxygen layers that occur before the onset of
collapse, as revealed by recent numerical simulations of the last stage of
massive star evolutions. Furthermore, it has been also demonstrated numerically
that accretions of such non-spherical envelopes could facilitate shock revival.
These two multi-dimensional may hence hold a key to successful explosions. In
this paper, we performed a linear stability analysis of the standing accretion
shock in core-collapse supernovae, taking into account non-spherical, unsteady
accretion flows onto the shock to clarify the possible links between the two
effects. We found that such pre-shock perturbations can excite the fluid
instabilities efficiently and hence help the shock revive in core-collapse
supernovae.


title: Coherent and incoherent nonparaxial self-accelerating Weber beams

abstract:
  We investigate the coherent and incoherent nonparaxial Weber beams,
theoretically and numerically. We show that the superposition of coherent
self-accelerating Weber beams with transverse displacement cannot display the
nonparaxial accelerating Talbot effect. The reason is that their lobes do not
accelerate in unison, which is a requirement for the appearance of the effect.
While for the incoherent Weber beams, they naturally cannot display the
accelerating Talbot effect but can display the nonparaxial accelerating
properties, although the transverse coherence length is smaller than the beam
width, based on the second-order coherence theory. Our research method directly
applies to the nonparaxial Mathieu beams as well, and one will obtain similar
conclusions as for the Weber beams, although this is not discussed in the
paper. Our investigation identifies families of nonparaxial accelerating beams
that do not exhibit the accelerating Talbot effect, and in addition broadens
the understanding of coherence properties of such nonparaxial accelerating
beams.


title: Predicting Human Intentions from Motion Only: A 2D+3D Fusion Approach

abstract:
  In this paper, we address the new problem of the prediction of human intents.
There is neuro-psychological evidence that actions performed by humans are
anticipated by peculiar motor acts which are discriminant of the type of action
going to be performed afterwards. In other words, an actual intent can be
forecast by looking at the kinematics of the immediately preceding movement. To
prove it in a computational and quantitative manner, we devise a new
experimental setup where, without using contextual information, we predict
human intents all originating from the same motor act. We posit the problem as
a classification task and we introduce a new multi-modal dataset consisting of
a set of motion capture marker 3D data and 2D video sequences, where, by only
analysing very similar movements in both training and test phases, we are able
to predict the underlying intent, i.e., the future, never observed action. We
also present an extensive experimental evaluation as a baseline, customizing
state-of-the-art techniques for either 3D and 2D data analysis. Realizing that
video processing methods lead to inferior performance but show complementary
information with respect to 3D data sequences, we developed a 2D+3D fusion
analysis where we achieve better classification accuracies, attesting the
superiority of the multimodal approach for the context-free prediction of human
intents.


title: Biconvex Relaxation for Semidefinite Programming in Computer Vision

abstract:
  Semidefinite programming is an indispensable tool in computer vision, but
general-purpose solvers for semidefinite programs are often too slow and memory
intensive for large-scale problems. We propose a general framework to
approximately solve large-scale semidefinite problems (SDPs) at low complexity.
Our approach, referred to as biconvex relaxation (BCR), transforms a general
SDP into a specific biconvex optimization problem, which can then be solved in
the original, low-dimensional variable space at low complexity. The resulting
biconvex problem is solved using an efficient alternating minimization (AM)
procedure. Since AM has the potential to get stuck in local minima, we propose
a general initialization scheme that enables BCR to start close to a global
optimum - this is key for our algorithm to quickly converge to optimal or
near-optimal solutions. We showcase the efficacy of our approach on three
applications in computer vision, namely segmentation, co-segmentation, and
manifold metric learning. BCR achieves solution quality comparable to
state-of-the-art SDP methods with speedups between 4X and 35X. At the same
time, BCR handles a more general set of SDPs than previous approaches, which
are more specialized.


title:
Short pulse generation and mode control of broadband terahertz quantum
  cascade lasers

abstract:
  We report on a waveguide engineering technique that enables the generation of
a bandwidth up to 1 THz and record ultra-short pulse length of 2.5 ps in
injection seeded terahertz quantum cascade lasers. The reported technique is
able to control and fully suppress higher order lateral modes in broadband
terahertz quantum cascade lasers by introducing side-absorbers to metal-metal
waveguides. The side-absorbers consist of a top metalization set-back with
respect to the laser ridge and an additional lossy metal layer. In continuous
wave operation the side-absorbers lead to octave spanning laser emission,
ranging from 1.63 to 3.37 THz, exhibiting a 725 GHz wide at top within a 10 dB
intensity range as well as frequency comb operation with a bandwidth of 442
GHz. Numerical and experimental studies have been performed to optimize the
impact of the side-absorbers on the emission properties and to determine the
required increase of waveguide losses. Furthermore, these studies have led to a
better understanding of the pulse formation dynamics of injection-seeded
quantum cascade lasers.


title: Neutron Star Kicks and their Relationship to Supernovae Ejecta Mass

abstract:
  We propose a simple model to explain the velocity of young neutron stars. We
attempt to confirm a relationship between the amount of mass ejected in the
formation of the neutron star and the `kick' velocity imparted to the compact
remnant resulting from the process. We assume the velocity is given by $v_{\rm
kick}=\alpha\,(M_{\rm ejecta} / M_{\rm remnant}) + \beta\,$. To test this
simple relationship we use the BPASS (Binary Population and Spectral Synthesis)
code to create stellar population models from both single and binary star
evolutionary pathways. We then use our Remnant Ejecta and Progenitor Explosion
Relationship (REAPER) code to apply different $\alpha$ and $\beta$ values and
three different `kick' orientations then record the resulting velocity
probability distributions.
  We find that while a single star population provides a poor fit to the
observational data, the binary population provides an excellent fit. Values of
$\alpha=70\, {\rm km\,s^{-1}}$ and $\beta=110\,{\rm km\,s^{-1}}$ reproduce the
\cite{RN165} observed 2-dimensional velocities and $\alpha=70\, {\rm
km\,s^{-1}}$ and $\beta=120\,{\rm km\,s^{-1}}$ reproduce their inferred
3-dimensional velocity distribution for nearby single neutron stars with ages
less than 3 Myrs. After testing isotropic, spin-axis aligned and orthogonal to
spin-axis `kick' orientations, we find no statistical preference for a `kick'
orientation. While ejecta mass cannot be the only factor that determines the
velocity of supernovae compact remnants, we suggest it is a significant
contributor and that the ejecta based `kick' should replace the
Maxwell-Boltzmann velocity distribution currently used in many population
synthesis codes.


title: Predicting System-level Power for a Hybrid Supercomputer

abstract:
  For current High Performance Computing systems to scale towards the holy
grail of ExaFLOP performance, their power consumption has to be reduced by at
least one order of magnitude. This goal can be achieved only through a
combination of hardware and software advances. Being able to model and
accurately predict the power consumption of large computational systems is
necessary for software-level innovations such as proactive and power-aware
scheduling, resource allocation and fault tolerance techniques. In this paper
we present a 2-layer model of power consumption for a hybrid supercomputer
(which held the top spot of the Green500 list on July 2013) that combines CPU,
GPU and MIC technologies to achieve higher energy efficiency. Our model takes
as input workload information - the number and location of resources that are
used by each job at a certain time - and calculates the resulting system-level
power consumption. When jobs are submitted to the system, the workload
configuration can be foreseen based on the scheduler policies, and our model
can then be applied to predict the ensuing system-level power consumption.
Additionally, alternative workload configurations can be evaluated from a power
perspective and more efficient ones can be selected. Applications of the model
include not only power-aware scheduling but also prediction of anomalous
behavior.


title: Hopf algebras of rooted forests, cocyles and free Rota-Baxter algebras

abstract:
  The Hopf algebra and the Rota-Baxter algebra are the two algebraic structures
underlying the algebraic approach of Connes and Kreimer to renormalization of
perturbative quantum field theory. In particular the Hopf algebra of rooted
trees serves as the "baby model" of Feynman graphs in their approach and can be
characterized by certain universal properties involving a Hochschild 1-cocycle.
Decorated rooted trees have also been applied to study Feynman graphs. We will
continue the study of universal properties of various spaces of decorated
rooted trees with such a 1-cocycle, leading to the concept of a cocycle Hopf
algebra. We further apply the universal properties to equip a free Rota-Baxter
algebra with the structure of a cocycle Hopf algebra or a cocycle bialgebra.


title:
Phase lags of quasi-periodic oscillations across source states in the
  low-mass X-ray binary 4U 1636-53

abstract:
  While there are many dynamical mechanisms and models that try to explain the
origin and phenomenology of the quasi-periodic oscillations (QPOs) seen in the
X-ray light curves of low-mass X-ray binaries, few of them address how the
radiative processes occurring in these extreme environments give rise to the
rich set of variability features actually observed in these light curves. A
step towards this end comes from the study of the energy and frequency
dependence of the phase lags of these QPOs. Here we used a methodology that
allowed us to study, for the first time, the dependence of the phase lags of
all QPOs in the range of 1 Hz to 1300 Hz detected in the low-mass X-ray binary
4U 1636-53 upon energy and frequency as the source changes its states as it
moves through the colour-colour diagram. Our results suggest that within the
context of models of up-scattering Comptonization, the phase lags dependencies
upon frequency and energy can be used to extract size scales and physical
conditions of the medium that produces the lags.


title:
Robust Deep-Learning-Based Road-Prediction for Augmented Reality
  Navigation Systems

abstract:
  This paper proposes an approach that predicts the road course from camera
sensors leveraging deep learning techniques. Road pixels are identified by
training a multi-scale convolutional neural network on a large number of
full-scene-labeled night-time road images including adverse weather conditions.
A framework is presented that applies the proposed approach to longer distance
road course estimation, which is the basis for an augmented reality navigation
application. In this framework long range sensor data (radar) and data from a
map database are fused with short range sensor data (camera) to produce a
precise longitudinal and lateral localization and road course estimation. The
proposed approach reliably detects roads with and without lane markings and
thus increases the robustness and availability of road course estimations and
augmented reality navigation. Evaluations on an extensive set of high precision
ground truth data taken from a differential GPS and an inertial measurement
unit show that the proposed approach reaches state-of-the-art performance
without the limitation of requiring existing lane markings.


title: Conjugate (nil) clean rings and Kothe's problem

abstract:
  Question 3 of [3] asks whether the matrix ring Mn(R) is nil clean, for any
nil clean ring R. It is shown that positive answer to this question is
equivalent to positive solution for Kothe's problem in the class of algebras
over the field F_2. Other equivalent problems are also discussed. The classes
of conjugate clean and conjugate nil clean rings, which lie strictly between
uniquely (nil) clean and (nil) clean rings are introduced and investigated.


title:
Disentangling genetic and environmental risk factors for individual
  diseases from multiplex comorbidity networks

abstract:
  Most disorders are caused by a combination of multiple genetic and/or
environmental factors. If two diseases are caused by the same molecular
mechanism, they tend to co-occur in patients. Here we provide a quantitative
method to disentangle how much genetic or environmental risk factors contribute
to the pathogenesis of 358 individual diseases, respectively. We pool data on
genetic, pathway-based, and toxicogenomic disease-causing mechanisms with
disease co-occurrence data obtained from almost two million patients. From this
data we construct a multilayer network where nodes represent disorders that are
connected by links that either represent phenotypic comorbidity of the patients
or the involvement of a certain molecular mechanism. From the similarity of
phenotypic and mechanism-based networks for each disorder we derive measure
that allows us to quantify the relative importance of various molecular
mechanisms for a given disease. We find that most diseases are dominated by
genetic risk factors, while environmental influences prevail for disorders such
as depressions, cancers, or dermatitis. Almost never we find that more than one
type of mechanisms is involved in the pathogenesis of diseases.


title: Strengthen Weak Measurement with Conjugated Destructive Interference

abstract:
  Standard weak measurement (SWM) has been proved to be a useful ingredient for
measuring small longitudinal phase shifts. [Phys. Rev. Lett. 111, 033604
(2013)]. In this letter, we show that with specfic pre-coupling and
postselection, destructive interference can be observed for the two conjugated
variables, i.e. time and frequency, of the meter state. Using a broad band
source, this conjugated destructive interference (CDI) can be observed in a
regime approximately 1 attosecond, while the related spectral shift reaches
hundreds of THz. This extreme sensitivity can be used to detect tiny
longitudinal phase perturbation. Combined with a frequency-domain analysis,
conjugated destructive interference weak measurement (CDIWM) is proved to
outperform SWM by two orders of magnitude.


title:
Relative contribution of the magnetic field barrier and solar wind speed
  in ICME-associated Forbush decreases

abstract:
  We study 50 cosmic ray Forbush decreases (FDs) from the Oulu neutron monitor
data during 1997-2005 that were associated with Earth-directed interplanetary
coronal mass ejections (ICMEs). Such events are generally thought to arise due
to the shielding of cosmic rays by a propagating diffusive barrier. The main
processes at work are the diffusion of cosmic rays across the large-scale
magnetic fields carried by the ICME and their advection by the solar wind. In
an attempt to better understand the relative importance of these effects, we
analyse the relationship between the FD profiles and those of the
interplanetary magnetic field (B) and the solar wind speed (Vsw). Over the
entire duration of a given FD, we find that the FD profile is generally well
(anti)correlated with the B and Vsw profiles. This trend holds separately for
the FD main and recovery phases too. For the recovery phases, however, the FD
profile is highly anti-correlated with the Vsw profile, but not with the B
profile. While the total duration of the FD profile is similar to that of the
Vsw profile, it is significantly longer than that of the B profile.

categories: physics.space-ph astro-ph.SR hep-ex physics.plasm-ph


title: Treatment of 4f states of the rare-earths: the case study of TbN

abstract:
  The lattice constant, bulk modulus and shear constant of TbN are calculated
by means of density functional theory (DFT) in the local density approximation
(LDA) and generalized gradient approximation (GGA), with 4f-states treated as
valence electrons or core electrons. In addition, local Coulomb repulsions U
are treated both statically as in the LDA+U approach and dynamically as in the
dynamical mean-field theory (DMFT) in the Hubbard-I approximation. It is shown
that all methods, except DFT-LDA with 4f electrons treated as either valence
states, produce lattice constants and bulk moduli in good agreement with
experiment. In the LDA+U approach multiple minima are found, and we focus on
the competition between a state with cubic symmetry and a state obtained from
atomic Hund's rules. We find the state with cubic symmetry to be 0.59 eV lower
in energy than the Hund's rules state, while the opposite was obtained in
previous literature. The shear constant is shown to be rather sensitive to the
theoretical method used, and the Hund's rules state obtained in LDA+U is found
to be unstable towards tetragonal shear. As to the magnetism, we find that the
calculation based on the Hubbard-I approximation reproduces observations with
the best accuracy. Finally, the spectral properties of TbN are discussed,
together with the general applicability of the different methods in describing
rare-earth elements and compounds.


title: Quantum interference in a Cooper pair splitter: The three sites model

abstract:
  New generation of Cooper pair splitters defined on hybrid nanostructures are
devices with high tunable coupling parameters. Transport measurements through
these devices revealed clear signatures of interference effects and motivated
us to introduce a new model, called the 3-sites model. These devices provide an
ideal playground to tune the Cooper pair splitting (CPS) efficency on demand,
and displays a rich variety of physical phenomena. In the present work we
analyze theoretically the conductance of the 3-sites model in the linear and
non-linear regimes and characterize the most representative features that arise
by the interplay of the different model parameters. In the linear regime we
find that the local processes typically exhibit Fano-shape resonances, while
the CPS contribution exhibits Lorentzian-shapes. Remarkably, we find that under
certain conditions, the transport is blocked by the presence of a dark state.
In the non-linear regime we established a hierarchy of the model parameters to
obtain the conditions for optimal efficency.


title: The valence and spectral properties of rare-earth clusters

abstract:
  The rare-earths are known to have intriguing changes of the valence,
depending on chemical surrounding or geometry. Here we make predictions from
theory that combines density functional theory with atomic multiplet-theory, on
the transition of valence when transferring from the atomic divalent limit to
the trivalent bulk, passing through different sized clusters, of selected
rare-earths. We predict that Tm clusters show an abrupt change from pure
divalent to pure trivalent at a size of 6 atoms, while Sm and Tb clusters are
respectively pure divalent and trivalent up to 8 atoms. Larger Sm clusters are
argued to likely make a transition to a mixed valent, or trivalent,
configuration. The valence of all rare-earth clusters, as a function of size,
is predicted from interpolation of our calculated results. We argue that the
here predicted behavior is best analyzed by spectroscopic measurements, and
provide theoretical spectra, based on dynamical mean field theory, in the
Hubbard-I approximation, to ease experimental analysis.


title:
Approximations for Apery's constant $\zeta(3)$ and rational series
  representations involving $\zeta(2n)$

abstract:
  In this note, using an idea from \cite{Amo-Carrillo-Sanchez} we derive some
new series representations involving $\zeta(2n)$ and Euler numbers. Using a
well-known series representation for the Clausen function, we also provide some
new representations of Apery's constant $\zeta(3)$. In particular cases, we
recover some well-known series representations of $\pi$.


title: Topological symmetry breaking in viscous coarsening

abstract:
  The crucial role of hydrodynamic pinch-off instabilities is evidenced in the
coarsening stage of viscous liquids. The phase separation of a barium
borosilicate glass melt is studied by in-situ synchrotron X-Ray tomography at
high temperature. The high viscosity contrast between the less viscous phase
and the more viscous phase induces a topological symmetry breaking: capillary
breakups occur preferentially in the less viscous phase. As a result,
contrasting morphologies are obtained in the two phases. This symmetry breaking
is illustrated on three different glass compositions , corresponding to
different volume fractions of the two phases. In particular, a fragmentation
phenomenon, reminiscent of the end-pinching mechanism proposed by Stone et al.
[1, 2] is evidenced in the less viscous phase.


title: Sparse Bayesian Inference of Multivariable ARX Networks

abstract:
  Increasing attention has recently been given to the inference of sparse
networks. In biology, for example, most molecules only bind to a small number
of other molecules, leading to sparse molecular interaction networks. To
achieve sparseness, a common approach consists of applying weighted penalties
to the number of links between nodes in the network and the complexity of the
dynamics of existing links. The selection of proper weights, however, is
non-trivial. Alternatively, this paper proposes a novel data-driven method,
called GESBL, that is able to penalise both network sparsity and model
complexity without any tuning. GESBL combines Sparse Bayesian Learning (SBL)
and Group Sparse Bayesian Learning (GSBL) to introduce penalties for
complexity, both in terms of element (system order of nonzero connections) and
group sparsity (network topology). The paper considers a class of sparse linear
time-invariant networks where the dynamics are represented by multivariable ARX
models. Data generated from sparse random ARX networks and synthetic gene
regulatory networks indicate that our method, on average, considerably
outperforms existing state-of-the-art methods. The proposed method can be
applied to a wide range of fields, from systems biology applications in
signalling and genetic regulatory networks to power systems.


title:
Magnetism and exchange interaction of small rare-earth clusters; Tb as a
  representative

abstract:
  Here we follow, both experimentally and theoretically, the development of
magnetism in Tb clusters from the atomic limit, adding one atom at a time. The
exchange interaction is, surprisingly, observed to drastically increase
compared to that of bulk, and to exhibit irregular oscillations as a function
of the interatomic distance. From electronic structure theory we find that the
theoretical magnetic moments oscillate with cluster size in exact agreement
with experimental data. Unlike the bulk, the oscillation is not caused by the
RKKY mechanism. Instead, the inter-atomic exchange is shown to be driven by a
competition between wave-function overlap of the 5d shell and the on-site
exchange interaction, which leads to a competition between ferromagnetic
double-exchange and antiferromagnetic super-exchange. This understanding opens
up new ways to tune the magnetic properties of rare-earth based magnets with
nano-sized building blocks.


title:
Connecting the dots III: Night side cooling and surface friction affect
  climates of tidally locked terrestrial planets

abstract:
  We investigate how night side cooling and surface friction impact surface
temperatures and large scale circulation for tidally locked Earth-like planets.
For each scenario, we vary the orbital period between $P_{rot}=1-100$~days and
capture changes in climate states.
  We find drastic changes in climate states for different surface friction
scenarios. For very efficient surface friction ($t_{s,fric}=$ 0.1 days), the
simulations for short rotation periods ($P_{rot} \leq$ 10 days) show
predominantly standing extra tropical Rossby waves. These waves lead to climate
states with two high latitude westerly jets and unperturbed meridional direct
circulation. In most other scenarios, simulations with short rotation periods
exhibit instead dominance by standing tropical Rossby waves. Such climate
states have a single equatorial westerly jet, which disrupts direct
circulation.
  Experiments with weak surface friction ($t_{s,fric}=~10 -100$ days) show
decoupling between surface temperatures and circulation, which leads to strong
cooling of the night side. The experiment with $t_{s,fric}= 100$ days assumes
climate states with easterly flow (retrograde rotation) for medium and slow
planetary rotations $P_{rot}= 12 - 100$~days.
  We show that an increase of night side cooling efficiency by one order of
magnitude compared to the nominal model leads to a cooling of the night side
surface temperatures by 80-100~K. The day side surface temperatures only drop
by 25~K at the same time. The increase in thermal forcing suppresses the
formation of extra tropical Rossby waves on small planets ($R_P=1 R_{Earth}$)
in the short rotation period regime ($P_{rot} \leq$ 10 days).


title: Semantic-Aware Depth Super-Resolution in Outdoor Scenes

abstract:
  While depth sensors are becoming increasingly popular, their spatial
resolution often remains limited. Depth super-resolution therefore emerged as a
solution to this problem. Despite much progress, state-of-the-art techniques
suffer from two drawbacks: (i) they rely on the assumption that intensity edges
coincide with depth discontinuities, which, unfortunately, is only true in
controlled environments; and (ii) they typically exploit the availability of
high-resolution training depth maps, which can often not be acquired in
practice due to the sensors' limitations. By contrast, here, we introduce an
approach to performing depth super-resolution in more challenging conditions,
such as in outdoor scenes. To this end, we first propose to exploit semantic
information to better constrain the super-resolution process. In particular, we
design a co-sparse analysis model that learns filters from joint intensity,
depth and semantic information. Furthermore, we show how low-resolution
training depth maps can be employed in our learning strategy. We demonstrate
the benefits of our approach over state-of-the-art depth super-resolution
methods on two outdoor scene datasets.


title: Correlation effects and orbital magnetism of Co clusters

abstract:
  Recent experiments on isolated Co clusters have shown huge orbital magnetic
moments in comparison with their bulk and surface counterparts. These clusters
hence provide the unique possibility to study the evolution of the orbital
magnetic moment with respect to the cluster size and how competing interactions
contribute to the quenching of orbital magnetism. We investigate here different
theoretical methods to calculate the spin and orbital moments of Co clusters,
and assess the performances of the methods in comparison with experiments. It
is shown that density functional theory in conventional local density or
generalized gradient approximations, or even with a hybrid functional, severely
underestimates the orbital moment. As natural extensions/corrections we
considered the orbital polarization correction, the LDA+U approximation as well
as the LDA+DMFT method. Our theory shows that of the considered methods, only
the LDA+DMFT method provides orbital moments in agreement with experiment, thus
emphasizing the importance of dynamic correlations effects for determining
fundamental magnetic properties of magnets in the nano-size regime.


title: Dynamics of Evolving Social Groups

abstract:
  Exclusive social groups are ones in which the group members decide whether or
not to admit a candidate to the group. Examples of exclusive social groups
include academic departments and fraternal organizations. In the present paper
we introduce an analytic framework for studying the dynamics of exclusive
social groups. In our model, every group member is characterized by his
opinion, which is represented as a point on the real line. The group evolves in
discrete time steps through a voting process carried out by the group's
members. Due to homophily, each member votes for the candidate who is more
similar to him (i.e., closer to him on the line). An admission rule is then
applied to determine which candidate, if any, is admitted. We consider several
natural admission rules including majority and consensus.
  We ask: how do different admission rules affect the composition of the group
in the long term? We study both growing groups (where new members join old
ones) and fixed-size groups (where new members replace those who quit). Our
analysis reveals intriguing phenomena and phase transitions, some of which are
quite counterintuitive.


title: High angular resolution SZ observations with NIKA and NIKA2

abstract:
  NIKA2 (New IRAM KID Arrays) is a dual band (150 and 260 GHz) imaging camera
based on Kinetic Inductance Detectors (KIDs) and designed to work at the IRAM
30 m telescope (Pico Veleta, Spain). Built on the experience of the NIKA
prototype, NIKA2 has been installed at the 30 m focal plane in October 2015 and
the commissioning phase is now ongoing. Through the thermal Sunyaev-Zeldovich
(tSZ) effect, NIKA2 will image the ionized gas residing in clusters of galaxies
with a resolution of 12 and 18 arcsec FWHM (at 150 and 260 GHz, respectively).
We report on the recent tSZ measurements with the NIKA camera and discuss the
future objectives for the NIKA2 SZ large Program, 300h of observation dedicated
to SZ science. With this program we intend to perform a high angular resolution
follow-up of a cosmologically-representative sample of clusters belonging to SZ
catalogues, with redshift greater than 0.5. The main output of the program will
be the study of the redshift evolution of the cluster pressure profile as well
as that of the scaling laws relating the cluster global properties.


title:
An algebraic description of screw dislocations in SC and BCC crystal
  lattices

abstract:
  We give an algebraic description of screw dislocations in a crystal,
especially simple cubic (SC) and body centered cubic (BCC) crystals, using free
abelian groups and fibering structures. We also show that the strain energy of
a screw dislocation based on the spring model is expressed by the
Epstein-Hurwitz zeta function approximately.

categories: math-ph cond-mat.mes-hall cond-mat.stat-mech math.AG math.AT math.MP


title:
Analysis of Remaining Uncertainties and Exponents under Various
  Conditional R\'{e}nyi Entropies

abstract:
  In this paper, we analyze the asymptotics of the normalized remaining
uncertainty of a source when a compressed or hashed version of it and
correlated side-information is observed. For this system, commonly known as
Slepian-Wolf source coding, we establish the optimal (minimum) rate of
compression of the source to ensure that the remaining uncertainties vanish. We
also study the exponential rate of decay of the remaining uncertainty to zero
when the rate is above the optimal rate of compression. In our study, we
consider various classes of random universal hash functions. Instead of
measuring remaining uncertainties using traditional Shannon information
measures, we do so using two forms of the conditional R\'{e}nyi entropy. Among
other techniques, we employ new one-shot bounds and the moments of type class
enumerator method for these evaluations. We show that these asymptotic results
are generalizations of the strong converse exponent and the error exponent of
the Slepian-Wolf problem under maximum \emph{a posteriori} (MAP) decoding.


title: Random Lasers for Broadband Directional Emission

abstract:
  Broadband coherent light sources are becoming increasingly important for
sensing and spectroscopic applications, especially in the mid-infrared and
terahertz (THz) spectral regions, where the unique absorption characteristics
of a whole host of molecules are located. The desire to miniaturize such light
emitters has recently lead to spectacular advances with compact on-chip lasers
that cover both of these spectral regions. The long wavelength and the small
size of the sources result in a strongly diverging laser beam that is difficult
to focus on the target that one aims to perform spectroscopy with. Here, we
introduce an unconventional solution to this vexing problem relying on a random
laser to produce coherent broadband THz radiation as well as an almost
diffraction limited far-field emission profile. Our random lasers do not
require any fine-tuning and thus constitute a promising example of practical
device applications for random lasing.


title: Attention Correctness in Neural Image Captioning

abstract:
  Attention mechanisms have recently been introduced in deep learning for
various tasks in natural language processing and computer vision. But despite
their popularity, the "correctness" of the implicitly-learned attention maps
has only been assessed qualitatively by visualization of several examples. In
this paper we focus on evaluating and improving the correctness of attention in
neural image captioning models. Specifically, we propose a quantitative
evaluation metric for the consistency between the generated attention maps and
human annotations, using recently released datasets with alignment between
regions in images and entities in captions. We then propose novel models with
different levels of explicit supervision for learning attention maps during
training. The supervision can be strong when alignment between regions and
caption entities are available, or weak when only object segments and
categories are provided. We show on the popular Flickr30k and COCO datasets
that introducing supervision of attention maps during training solidly improves
both attention correctness and caption quality, showing the promise of making
machine perception more human-like.


title:
Potential of enhancing a natural convection loop with a
  thermomagnetically pumped ferrofluid

abstract:
  The feasibility of using a thermomagnetically pumped ferrofluid to enhance
the performance of a natural convection cooling loop is investigated. First, a
simplified analytical estimate for the thermomagnetic pumping action is
derived, and then design rules for optimal solenoid and ferrofluid are
presented. The design rules are used to set up a medium-scale (1 m, 10-1000 W)
case study, which is modeled using a previously published and validated model
(Aursand et al. [1]). The results show that the thermomagnetic driving force is
significant compared to the natural convection driving force, and may in some
cases greatly surpass it. The results also indicate that cooling performance
can be increased by factors up to 4 and 2 in the single-phase and two- phase
regimes, respectively, even when taking into the account the added heat from
the solenoid. The performance increases can alternatively be used to obtain a
reduction in heat-sink size by up to 75 %.


title:
Divisibility and coherence properties of an open quantum system: role of
  the interaction with the environment

abstract:
  In the present work we recall and extend the results of previous work
concerning the time evolution of open quantum systems. We show how general
properties of such systems are related to their structure properties, those of
their environments and the interaction between the systems and the
environments.


title:
Singularities of the representation variety of the braid group on 3
  strands

abstract:
  The singularities of the representation variety of $B_3$ are studied, where
$B_3$ is the knot group on 3 strands. Specifically, we determine which
semisimple representations are smooth points of this variety.


title:
Verification of general Markov decision processes by approximate
  similarity relations and policy refinement

abstract:
  In this work we introduce new approximate similarity relations that are shown
to be key for policy (or control) synthesis over general Markov decision
processes. The models of interest are discrete-time Markov decision processes,
endowed with uncountably-infinite state spaces and metric output (or
observation) spaces. The new relations, underpinned by the use of metrics,
allow in particular for a useful trade-off between deviations over probability
distributions on states, and distances between model outputs. We show that the
new probabilistic similarity relations, inspired by a notion of simulation
developed for finite-state models, can be effectively employed over general
Markov decision processes for verification purposes, and specifically for
control refinement from abstract models.


title: Dynamic index and LZ factorization in compressed space

abstract:
  In this paper, we propose a new \emph{dynamic compressed index} of $O(w)$
space for a dynamic text $T$, where $w = O(\min(z \log N \log^*M, N))$ is the
size of the signature encoding of $T$, $z$ is the size of the Lempel-Ziv77
(LZ77) factorization of $T$, $N$ is the length of $T$, and $M \geq 3N$ is an
integer that can be handled in constant time under word RAM model. Our index
supports searching for a pattern $P$ in $T$ in $O(|P| f_{\mathcal{A}} + \log w
\log |P| \log^* M (\log N + \log |P| \log^* M) + \mathit{occ} \log N)$ time and
insertion/deletion of a substring of length $y$ in $O((y+ \log N\log^* M)\log w
\log N \log^* M)$ time, where $f_{\mathcal{A}} = O(\min \{ \frac{\log\log M
\log\log w}{\log\log\log M}, \sqrt{\frac{\log w}{\log\log w}} \})$. Also, we
propose a new space-efficient LZ77 factorization algorithm for a given text of
length $N$, which runs in $O(N f_{\mathcal{A}} + z \log w \log^3 N (\log^*
N)^2)$ time with $O(w)$ working space.


title: Modeling Photographic Composition via Triangles

abstract:
  The capacity of automatically modeling photographic composition is valuable
for many real-world machine vision applications such as digital photography,
image retrieval, image understanding, and image aesthetics assessment. The
triangle technique is among those indispensable composition methods on which
professional photographers often rely. This paper proposes a system that can
identify prominent triangle arrangements in two major categories of
photographs: natural or urban scenes, and portraits. For the natural or urban
scene pictures, the focus is on the effect of linear perspective. For
portraits, we carefully examine the positioning of human subjects in a photo.
We show that line analysis is highly advantageous for modeling composition in
both categories. Based on the detected triangles, new mathematical descriptors
for composition are formulated and used to retrieve similar images. Leveraging
the rich source of high aesthetics photos online, similar approaches can
potentially be incorporated in future smart cameras to enhance a person's photo
composition skills.


title: Gather-and-broadcast frequency control in power systems

abstract:
  We propose a novel frequency control approach in between centralized and
distributed architectures, that is a continuous-time feedback control version
of the dual decomposition optimization method. Specifically, a convex
combination of the frequency measurements is centrally aggregated, followed by
an integral control and a broadcast signal, which is then optimally allocated
at local generation units. We show that our gather-and-broadcast control
architecture comprises many previously proposed strategies as special cases. We
prove local asymptotic stability of the closed-loop equilibria of the
considered power system model, which is a nonlinear differential-algebraic
system that includes traditional generators, frequency-responsive devices, as
well as passive loads, where the sources are already equipped with primary
droop control. Our feedback control is designed such that the closed-loop
equilibria of the power system solve the optimal economic dispatch problem.


title: A minimal integrity basis for the elasticity tensor

abstract:
  We definitively solve the old problem of finding a minimal integrity basis of
polynomial invariants of the fourth-order elasticity tensor C. Decomposing C
into its SO(3)-irreducible components we reduce this problem to finding joint
invariants of a triplet (a, b, D), where a and b are second-order harmonic
tensors, and D is a fourth-order harmonic tensor. Combining theorems of
classical invariant theory and formal computations, a minimal integrity basis
of 297 polynomial invariants for the elasticity tensor is obtained for the
first time.


title: Introduction to complex dynamics in one dimension

abstract:
  These are notes from elementary lectures given in the summer of 2013 at the
YMSC center at Tsinghua University in Beijing.


title: Beyond the thermal model in relativistic heavy-ion collisions

abstract:
  Deviations from thermal distribution functions of produced particles in
relativistic heavy-ion collisions are discussed as indicators for
nonequilibrium processes. The focus is on rapidity distributions of produced
charged hadrons as functions of collision energy and centrality which are used
to infer the fraction of produced particles from a central fireball as compared
to the one from the fragmentation sources that are out of equilibrium with the
rest of the system. Overall thermal equilibrium would only be reached for large
times t -> infinity.


title:
Determining the Characteristic Vocabulary for a Specialized Dictionary
  using Word2vec and a Directed Crawler

abstract:
  Specialized dictionaries are used to understand concepts in specific domains,
especially where those concepts are not part of the general vocabulary, or
having meanings that differ from ordinary languages. The first step in creating
a specialized dictionary involves detecting the characteristic vocabulary of
the domain in question. Classical methods for detecting this vocabulary involve
gathering a domain corpus, calculating statistics on the terms found there, and
then comparing these statistics to a background or general language corpus.
Terms which are found significantly more often in the specialized corpus than
in the background corpus are candidates for the characteristic vocabulary of
the domain. Here we present two tools, a directed crawler, and a distributional
semantics package, that can be used together, circumventing the need of a
background corpus. Both tools are available on the web.


title: Low-energy Antikaon Interaction with Nuclei: The AMADEUS Challenge

abstract:
  The low-energy strong interaction of antikaons (K-) with nuclei has many
facets and rep- resents a lively and challenging research field. It is
interconnected to the peculiar role of strangeness, since the strange quark is
rather light, but still much heavier than the up and down quarks. Thus, when
strangeness is involved one has to deal with spontaneous and explicit symmetry
breaking in QCD. It is well known that the antikaon interaction with nucleons
is attractive, but how strong ? Is the interaction strong enough to bind
nucleons to form kaonic nuclei and, if so, what are the properties (binding
energy, decay width)? There are controversial indications for such bound states
and new results are expected to come soon. The existence of antikaon mediated
bound states might have important consequences since it would open the
possibility for the formation of cold baryonic matter of high density which
might have a severe impact in astrophysics for the understanding of the
composi- tion of compact (neutron) stars. New experimental opportunities could
be provided by the AMADEUS experiment at the DA?NE electron-positron collider
at LNF-INFN (Frascati, Italy). Pre-AMADEUS studies on the antikaon interaction
with nuclei are carried out by analysis of data collected by KLOE in till 2005
and in special data runs using a carbon target insert. Studies for the
dedicated AMADEUS detector setup taking advantage of the low-energy antikaons
from Phi-meson decay delivered by DAFNE are in progress. Some re- sults
obtained so far and the perspectives of the AMADEUS experiment are presented
and discussed.


title: From Adhesive to Brittle Delamination in Visco-Elastodynamics

abstract:
  In this paper we analyze a system for brittle delamination between two
visco-elastic bodies, also subject to inertia, which can be interpreted as a
model for dynamic fracture. The rate-independent flow rule for the delamination
parameter is coupled with the momentum balance for the displacement, including
inertia. This model features a nonsmooth constraint ensuring the continuity of
the displacements outside the crack set, which is marked by the support of the
delamination parameter. A weak solvability concept, generalizing the notion of
energetic solution for rate-independent systems to the present mixed
rate-dependent/rate-independent frame, is proposed. Via refined variational
convergence techniques, existence of solutions is proved by passing to the
limit in approximating systems which regularize the nonsmooth constraint by
conditions for adhesive contact. The presence of the inertial term requires the
design of suitable recovery spaces small enough to provide compactness but
large enough to recover the information on the crack set in the limit.


title: Extended HI disks in nearby spiral galaxies

abstract:
  In this short write-up, I will concentrate on a few topics of interest. In
the 1970s I found very extended HI disks in galaxies such as NGC 5055 and NGC
2841, out to 2 - 2.5 times the Holmberg radius. Since these galaxies are
warped, a "tilted ring model" allows rotation curves to be derived, and
evidence for dark matter to be found. The evaluation of the amount of dark
matter is hampered by a disk-halo degeneracy, which can possibly be broken by
observations of velocity dispersions in both the MgI region and the CaII
region.


title:
Measurement of a microwave field amplitude beyond the standard quantum
  limit

abstract:
  We report a quantum measurement beyond the standard quantum limit (SQL) for
the amplitude of a small displacement acting on a cavity field. This
measurement uses as resource an entangled mesoscopic state, prepared by the
resonant interaction of a circular Rydberg atom with a field stored in a
superconducting cavity. We analyse the measurement process in terms of Fisher
information and prove that it is, in principle, optimal. The achieved
experimental precision, 2.4 dB below the SQL, is well understood in terms of
experimental imperfections.This method could be transposed to other systems,
particularly to circuit QED, for the precise measurements of weak forces acting
on oscillators.


title:
Sharp boundary behavior of eigenvalues for Aharonov-Bohm operators with
  varying poles

abstract:
  In this paper, we investigate the behavior of the eigenvalues of a magnetic
Aharonov-Bohm operator with half-integer circulation and Dirichlet boundary
conditions in a bounded planar domain. We establish a sharp relation between
the rate of convergence of the eigenvalues as the singular pole is approaching
a boundary point and the number of nodal lines of the eigenfunction of the
limiting problem, i.e. of the Dirichlet Laplacian, ending at that point. The
proof relies on the construction of a limit profile depending on the direction
along which the pole is moving, and on an Almgren-type monotonicity argument
for magnetic operators.


title:
Control of underwater vehicles in inviscid fluids--II. Flows with
  vorticity

abstract:
  In a recent paper, the authors investigated the controllability of an
underwater vehicle immersed in an infinite volume of an inviscid fluid,
assuming that the flow was irrotational. The aim of the present paper is to
pursue this study by considering the more general case of a flow with
vorticity. It is shown here that the local controllability of the position and
the velocity of the underwater vehicle (a vector in R 12) holds in a flow with
vorticity whenever it holds in a flow without vorticity.


title:
LiSK - A C++ Library for Evaluating Classical Polylogarithms and
  $\text{Li}_{22}$

abstract:
  I present a lightweight C++ library for the evaluation of classical
polylogarithms Li_n and the special function Li_{22} for arbitrary complex
arguments. The evaluation is possible in arbitrary precision arithmetic and
features also an explicit double precision implementation for a much faster
numerical evaluation. The implementation is based on arXiv:1601.02649.


title:
Simultaneous VLBA polarimetric observations of the v=$\{$1,2$\}$ J=1-0
  and v=1, J=2-1 SiO maser emission toward VY CMa II: component-level
  polarization analysis

abstract:
  This paper presents a component-level comparison of the polarized v=1 J =1-0,
v=2 J=1-0 and v=1 J=2-1 SiO maser emission towards the supergiant star VY CMa
at milliarcsecond-scale, as observed using the VLBA at $\lambda=7$mm and
$\lambda=3$mm. An earlier paper considered overall maser morphology and
constraints on SiO maser excitation and pumping derived from these data. The
goal of the current paper is to use the measured polarization properties of
individual co-spatial components detected across multiple transitions to
provide constraints on several competing theories for the transport of
polarized maser emission. This approach minimizes the significant effects of
spatial blending. We present several diagnostic tests designed to distinguish
key features of competing theoretical models for maser polarization. The number
of coincident features is limited by sensitivity however, particularly in the
v=1 J=2-1 transition at 86 GHz, and deeper observations are needed. Preliminary
conclusions based on the current data provide some support for: i)
spin-independent solutions for linear polarization; ii) the influence of
geometry on the distribution of fractional linear polarization with intensity;
and, iii) $\pi/2$ rotations in linear polarization position angle arising from
transitions across the Van Vleck angle ($\sin^2{\theta}=2/3$) between the maser
line-of-sight and magnetic field. There is weaker evidence for several
enumerated non-Zeeman explanations for circular polarization. The expected 2:1
ratio in circular polarization between J=1-0 and J=2-1 predicted by standard
Zeeman theory cannot unfortunately be tested conclusively due to insufficient
coincident components.


title:
A multi-phase ferrofluid flow model with equation of state for
  thermomagnetic pumping and heat transfer

abstract:
  A one-dimensional multi-phase flow model for thermomagnetically pumped
ferrofluid with heat transfer is proposed. The thermodynamic model is a
combination of a simplified particle model and thermodynamic equations of state
for the base fluid. The magnetization model is based on statistical mechanics,
taking into account non-uniform particle size distributions. An implementation
of the proposed model is validated against experiments from the literature, and
found to give good predictions for the thermomagnetic pumping performance.
However, the results reveal a very large sensitivity to uncertainties in heat
transfer coefficient predictions.


title: On the Benjamin-Bona-Mahony equation with a localized damping

abstract:
  We introduce several mechanisms to dissipate the energy in the
Benjamin-Bona-Mahony (BBM) equation. We consider either a distributed
(localized) feedback law, or a boundary feedback law. In each case, we prove
the global wellposedness of the system and the convergence towards a solution
of the BBM equation which is null on a band. If the Unique Continuation
Property holds for the BBM equation, this implies that the origin is
asymp-totically stable for the damped BBM equation.


title:
Some Calculations of the Lusztig-Vogan Bijection for Classical Nilpotent
  Orbits

abstract:
  In this manuscript, we compute explicitly the Lusztig-Vogan bijection for
local systems of some classical, special, nilpotent orbits. Using these
results, we prove a conjecture of Achar and Sommers on regular functions of
some covers of classical nilpotent orbits.


title: The causal topology of neutral 4-manifolds with null boundary

abstract:
  This paper considers aspects of 4-manifold topology from the point of view of
the null cone of a neutral metric, a point of view we call neutral causal
topology. In particular, we construct and investigate neutral 4-manifolds with
null boundaries that arise from canonical 3- and 4-dimensional settings.
  A null hypersurface is foliated by its normal and, in the neutral case,
inherits a pair of totally null planes at each point. This paper focuses on
these plane bundles in a number of classical settings
  The first construction is the conformal compactification of flat neutral
4-space into the 4-ball. The null foliation on the boundary in this case is the
Hopf fibration on the 3-sphere and the totally null planes in the boundary are
integrable. The metric on the 4-ball is a conformally flat, scalar-flat,
positive Ricci curvature neutral metric.
  The second constructions are subsets of the 4-dimensional space of oriented
geodesics in a 3-dimensional space-form, equipped with its canonical neutral
metric. We consider all oriented geodesics tangent to a given embedded strictly
convex 2-sphere.
  The third is a neutral geometric model for the intersection of two surfaces
in a 4-manifold. The surfaces are the sets of oriented normal lines to two
round spheres in Euclidean 3-space, which form Lagrangian surfaces in the
4-dimensional space of all oriented lines. The intersection of the boundaries
of their normal neighbourhoods form tori that we prove are totally real and
Lorentz if the spheres do not intersect.
  We conclude with possible topological applications of the three
constructions, including neutral Kirby calculus, neutral knot invariants and
neutral Casson handles, respectively.


title:
Thermoelectric properties of iron-based superconductors and parent
  compounds

abstract:
  Herewith, we review the available experimental data of thermoelectric
transport properties of iron-based superconductors and parent compounds. We
discuss possible physical mechanisms into play in determining the Seebeck
effect, from whence one can extract information about Fermi surface
reconstruction and Lifshitz transitions, multiband character, coupling of
charge carriers with spin excitations and its relevance in the unconventional
superconducting pairing mechanism, nematicity, quantum critical fluctuations
close to the optimal doping for superconductivity, correlation. Additional
information is obtained from the analysis of the Nernst effect, whose
enhancement in parent compounds must be related partially to multiband
transport and low Fermi level, but mainly to the presence of Dirac cone bands
at the Fermi level. In the superconducting compounds, large Nernst effect in
the normal state is explained in terms of fluctuating precursors of the spin
density wave state, while in the superconducting state it mirrors the usual
vortex liquid dissipative regime. A comparison between the phenomenology of
thermoelectric behavior of different families of iron-based superconductors and
parent compounds allows to evidence the key differences and analogies, thus
providing clues on the rich and complex physics of these fascinating
unconventional superconductors.


title: A multi-milliJoule femtosecond Raman laser emitting at 1.28 um

abstract:
  We report on the generation of broadband, high-energy femtosecond pulses
centered at 1.28 um by stimulated Raman scattering in pressurized hydrogen
cell. Stimulated Raman scattering is performed by two chirped and delayed
pulses originating from a multi-mJ Ti:Sapphire amplifier. The Stokes pulse
carries energy of 4.4 mJ and is recompressed down to 66 fs by reflective
grating pair. We characterized the short-wavelength mid-infrared source in view
of energy stability, beam profile and conversion efficiency at a repetition
rate of 100 Hz and 10 Hz. The demonstrated laser will benefit intense THz
generation applications from highly nonlinear organic crystals.


title: On level-transitivity and exponential growth

abstract:
  We prove that if the group generated by a Mealy automaton acts
level-transitively on a regular rooted tree, then the semigroup generated by
the dual automaton has exponential growth, hence giving a decision procedure of
exponential growth for a restricted family of automaton semigroups.


title: A primer on quantum fluids

abstract:
  This book introduces the theoretical description and properties of quantum
fluids. The focus is on gaseous atomic Bose-Einstein condensates and, to a
minor extent, superfluid helium, but the underlying concepts are relevant to
other forms of quantum fluids such as polariton and photonic condensates. The
book is pitched at the level of advanced undergraduates and early postgraduate
students, aiming to provide the reader with the knowledge and skills to develop
their own research project on quantum fluids. Indeed, the content for this book
grew from introductory notes provided to our own research students. It is
assumed that the reader has prior knowledge of undergraduate mathematics and/or
physics; otherwise, the concepts are introduced from scratch, often with
references for directed further reading.


title: Excitons in boron nitride single layer

abstract:
  Boron nitride single layer belongs to the family of 2D materials whose
optical properties are currently receiving considerable attention. Strong
excitonic effects have already been observed in the bulk and still stronger
effects are predicted for single layers. We present here a detailed study of
these properties by combining \textit{ab initio} calculations and a
tight-binding-Wannier analysis in both real and reciprocal space. Due to the
simplicity of the band structure with single valence ($\pi$) and conduction
($\pi^*$) bands the tight-binding analysis becomes quasi quantitative with only
two adjustable parameters and provides tools for a detailed analysis of the
exciton properties. Strong deviations from the usual hydrogenic model are
evidenced. The ground state exciton is not a genuine Frenkel exciton, but a
very localized "tightly-bound" one. The other ones are similar to those found
in transition metal dichalcogenides and, although more localized, can be
described within a Wannier-Mott scheme.


title: Model-driven Simulations for Deep Convolutional Neural Networks

abstract:
  The use of simulated virtual environments to train deep convolutional neural
networks (CNN) is a currently active practice to reduce the
(real)data-hungriness of the deep CNN models, especially in application domains
in which large scale real data and/or groundtruth acquisition is difficult or
laborious. Recent approaches have attempted to harness the capabilities of
existing video games, animated movies to provide training data with high
precision groundtruth. However, a stumbling block is in how one can certify
generalization of the learned models and their usefulness in real world data
sets. This opens up fundamental questions such as: What is the role of
photorealism of graphics simulations in training CNN models? Are the trained
models valid in reality? What are possible ways to reduce the performance bias?
In this work, we begin to address theses issues systematically in the context
of urban semantic understanding with CNNs. Towards this end, we (a) propose a
simple probabilistic urban scene model, (b) develop a parametric rendering tool
to synthesize the data with groundtruth, followed by (c) a systematic
exploration of the impact of level-of-realism on the generality of the trained
CNN model to real world; and domain adaptation concepts to minimize the
performance bias.


title: Equilibrium states and hidden attractors in Chua circuit

abstract:
  The dynamics of the Chua circuit is studied. Analysis of equilibrium states
was revealed. Parameter plane of the picewise linear voltage-current was
obtained. For this system was shown sequence of bifurcations of symmetry
broken.


title:
A Sparse Representation of Complete Local Binary Pattern Histogram for
  Human Face Recognition

abstract:
  Human face recognition has been a long standing problem in computer vision
and pattern recognition. Facial analysis can be viewed as a two-fold problem,
namely (i) facial representation, and (ii) classification. So far, many face
representations have been proposed, a well-known method is the Local Binary
Pattern (LBP), which has witnessed a growing interest. In this respect, we
treat in this paper the issues of face representation as well as classification
in a novel manner. On the one hand, we use a variant to LBP, so-called Complete
Local Binary Pattern (CLBP), which differs from the basic LBP by coding a given
local region using a given central pixel and Sing_ Magnitude difference.
Subsequently, most of LBPbased descriptors use a fixed grid to code a given
facial image, which technique is, in most cases, not robust to pose variation
and misalignment. To cope with such issue, a representative Multi-Resolution
Histogram (MH) decomposition is adopted in our work. On the other hand, having
the histograms of the considered images extracted, we exploit their sparsity to
construct a so-called Sparse Representation Classifier (SRC) for further face
classification. Experimental results have been conducted on ORL face database,
and pointed out the superiority of our scheme over other popular
state-of-the-art techniques.


title: Free Subalgebras of Graded Algebras

abstract:
  Let $k$ be a field and let $A=\bigoplus_{n\ge 1}A_n$ be a positively graded
$k$-algebra. We recall that $A$ is graded nilpotent if for every $d\ge 1$, the
subalgebra of $A$ generated by elements of degree $d$ is nilpotent. We give a
method of producing grading nilpotent algebras and use this to prove that over
any base field $k$ there exists a finitely generated graded nilpotent algebra
that contains a free $k$-subalgebra on two generators.


title: Towards the bounce inflationary gravitational wave

abstract:
  In bounce inflation scenario, the inflation is singularity-free, while the
advantages of inflation are reserved. We analytically calculate the power
spectrum of its primordial gravitational waves (GWs), and show a universal
result including the physics of the bounce phase. The spectrum acquires a
cutoff at large scale, while the oscillation around the cutoff scale is quite
drastic, which is determined by the details of bounce. Our work highlights that
the primordial GWs at large scale may encode the physics of the bounce ever
happened at about $\sim 60$ efolds before inflation.


title: Minimal digraph obstructions for small matrices

abstract:
  Given a $\{ 0, 1, \ast \}$-matrix $M$, a minimal $M$-obstruction is a digraph
$D$ such that $D$ is not $M$-partitionable, but every proper induced subdigraph
of $D$ is. In this note we present a list of all the $M$-obstructions for every
$2 \times 2$ matrix $M$.
  Notice that this note will be part of a larger paper, but we are archiving it
now so we can cite the results.


title:
Frequency dependent magneto-optical conductivity in the generalized
  $\alpha - T_3$ model

abstract:
  We have studied a generalized three band crossing model in 2D, the
generalized $\alpha - T_3$ lattice, ranging from the pseudospin-1 Dirac
equation through a quadratic+flat band touching to the pseudospin-1/2 Dirac
equation. A general method is presented to determine the operator form of the
Green's function, being gauge and representation independent. This yields the
Landau level structure in a quantizing magnetic field and the longitudinal and
transversal magneto-optical conductivities of the underlying system Although
the magneto-optical selection rules allow for many transitions between Landau
levels, the dominant one stems from exciting a particle from/to the flat band
to/from a propagating band. The Hall conductivity from each valley is rational
(not quantized at all), in agreement with Berry phase considerations, though
their sum is always integer quantized.


title: A dichotomy for the kernel by $H$-walks problem in digraphs

abstract:
  Let $H = (V_H, A_H)$ be a digraph which may contain loops, and let $D = (V_D,
A_D)$ be a loopless digraph with a coloring of its arcs $c: A_D \to V_H$. An
$H$-walk of $D$ is a walk $(v_0, \dots, v_n)$ of $D$ such that $(c(v_{i-1},
v_i), c(v_i, v_{i+1}))$ is an arc of $H$, for every $1 \le i \le n-1$. For $u,
v \in V_D$, we say that $u$ reaches $v$ by $H$-walks if there exists an
$H$-walk from $u$ to $v$ in $D$. A subset $S \subseteq V_D$ is a kernel by
$H$-walks of $D$ if every vertex in $V_D \setminus S$ reaches by $H$-walks some
vertex in $S$, and no vertex in $S$ can reach another vertex in $S$ by
$H$-walks.
  A panchromatic pattern is a digraph $H$ such that every arc-colored digraph
$D$ has a kernel by $H$-walks. In this work, we prove that every digraph $H$ is
either a panchromatic pattern, or the problem of determining whether an
arc-colored digraph $D$ has a kernel by $H$-walks is $NP$-complete.


title: Pure spin current devices based on ferromagnetic topological insulators

abstract:
  Two-dimensional topological insulators possess two counter propagating edge
channels with op- posite spin direction. Recent experimental progress allowed
to create ferromagnetic topological insulators realizing a quantum anomalous
Hall (QAH) state. In the QAH state one of the two edge channels disappears due
to the strong ferromagnetic exchange field. We investigate heterostuctures of
topological insulators and ferromagnetic topological insulators by means of
numerical transport calculations. We show that spin current flow in such
heterostructures can be controlled with high fidelity. Specifically, we propose
spintronic devices that are capable of creating, switching and de- tecting pure
spin currents using the same technology. In these devices electrical currents
are directly converted into spin currents, allowing a high conversion
efficiency. Energy independent transport properties in combination with large
bulk gaps in some topological insulator materials may allow operation even at
room temperature.