title:
The Linearized Inverse Problem in Multifrequency Electrical Impedance
  Tomography

abstract:
  This paper provides an analysis of the linearized inverse problem in
multifrequency electrical impedance tomography. We consider an isotropic
conductivity distribution with a finite number of unknown inclusions with
different frequency dependence, as is often seen in biological tissues. We
discuss reconstruction methods for both fully known and partially known
spectral profiles, and demonstrate in the latter case the successful employment
of difference imaging. We also study the reconstruction with an imperfectly
known boundary, and show that the multifrequency approach can eliminate
modeling errors and recover almost all inclusions. In addition, we develop an
efficient group sparse recovery algorithm for the robust solution of related
linear inverse problems. Several numerical simulations are presented to
illustrate and validate the approach.


title: Gate dependent electronic Raman scattering in graphene

abstract:
  We report the direct observation of polarization resolved electronic Raman
scattering in a gated monolayer graphene device. The evolution of the
electronic Raman scattering spectra with gate voltage and its polarization
dependence are in full agreement with theoretical expectations for non-resonant
Raman processes involving interband electron-hole excitations across the Dirac
cone. We further show that the spectral dependence of the electronic Raman
scattering signal can be simply described by the dynamical polarizability of
graphene in the long wavelength limit. The possibility to directly observe
Dirac fermion excitations in graphene opens the way to promising Raman
investigations of electronic properties of graphene and other 2D crystals.


title:
Simple transitive 2-representations for some 2-subcategories of Soergel
  bimodules

abstract:
  We classify simple transitive $2$-representations of certain
$2$-sub\-ca\-te\-go\-ri\-es of the $2$-category of Soergel bimodules over the
coinvariant algebra in Coxeter types $B_2$ and $I_2(5)$. In the $I_2(5)$ case
it turns out that simple transitive $2$-representations are exhausted by cell
$2$-representations. In the $B_2$ case we show that, apart from cell
$2$-representations, there is a unique, up to equivalence, additional simple
transitive $2$-representation and we give an explicit construction of this
$2$-representation.


title:
Complete band gaps including non-local effects occur only in the relaxed
  micromorphic model

abstract:
  In this paper we substantiate the claim implicitly made in previous works
that the relaxed micromorphic model is the only linear, isotropic, reversibly
elastic, nonlocal generalized continuum model able to describe complete
band-gaps on a phenomenological level. To this end, we recapitulate the
response of the standard Mindlin-Eringen micromorphic model with the full
micro-distortion gradient of P, the relaxed micromorphic model depending only
on the Curl P of the micro-distortion P, and a variant of the standard
micromorphic model in which the curvature depends only on the divergence Div P
of the micro distortion. The Div-model has size-effects but the dispersion
analysis for plane waves shows the incapability of that model to even produce a
partial band gap. Combining the curvature to depend quadratically on Div P and
Curl P shows that such a model is similar to the standard Mindlin-Eringen model
which can eventually show only a partial band gap.


title: Half-regular factorizations of the complete bipartite graph

abstract:
  We consider a bipartite version of the color degree matrix problem. A
bipartite graph $G(U,V,E)$ is half-regular if all vertices in $U$ have the same
degree. We give necessary and sufficient conditions for a bipartite degree
matrix (also known as demand matrix) to be the color degree matrix of an
edge-disjoint union of half-regular graphs. We also give necessary and
sufficient perturbations to transform realizations of a half-regular degree
matrix into each other. Based on these perturbations, a Markov chain Monte
Carlo method is designed in which the inverse of the acceptance ratios are
polynomial bounded.
  Realizations of a half-regular degree matrix are generalizations of Latin
squares, and they also appear in applied neuroscience.


title: On the regularity of primes in arithmetic progressions

abstract:
  We prove that for a positive integer $k$ the primes in certain kinds of
intervals can not distribute too 'uniformly' among the reduced residue classes
modulo $k$. Hereby, we prove a generalization of a conjecture of Recaman and
establish our results in a much more general situation, in particular for prime
ideals in number fields.


title:
Diffusion phenomena for the wave equation with space-dependent damping
  in an exterior domain

abstract:
  In this paper, we consider the asymptotic behavior of solutions to the wave
equation with space-dependent damping in an exterior domain. We prove that when
the damping is effective, the solution is approximated by that of the
corresponding heat equation as time tends to infinity. Our proof is based on
semigroup estimates for the corresponding heat equation and weighted energy
estimates for the damped wave equation. The optimality of the decay late for
solutions is also established.


title:
Non-spectral modes and how to find them in the Ornstein-Uhlenbeck
  process with white {\mu}-stable noise

abstract:
  We consider the Ornstein-Uhlenbeck process with a broad initial probability
distribution (Levy distribution), which exhibits so-called non-spectral modes.
The relaxation of such modes differs from those determined from the parameters
of the corresponding Fokker-Planck equation. The first non-spectral mode is
shown to govern the relaxation process and allows for estimation of the initial
distribution's Levy index. A method based on continuous wavelet transformation
is proposed to extract both (spectral and non-spectral) relaxation rates from a
stochastic data sample.


title: Lax operator algebras and integrable systems

abstract:
  A new class of infinite-dimensional Lie algebras given a name of Lax operator
algebras, and the related unifying approach to finite-dimensional integrable
systems with spectral parameter on a Riemann surface, such as Calogero--Moser
and Hitchin systems, are presented. In particular, our approach includes (the
non-twisted) Kac--Moody algebras and integrable systems with rational spectral
parameter. The presentation is based on the quite simple ideas related to
gradings of semisimple Lie algebras, and their interaction with the
Riemann--Roch theorem. The basic properties of the Lax operator algebras, as
well as the basic facts of the theory of integrable systems in question, are
treated (and proven) from this general point of view, in particular existence
of commutative hierarchies and their Hamiltonian properties. We conclude with
an application of the Lax operator algebras to prequantization of
finite-dimensional integrable systems.


title: Silting modules over commutative rings

abstract:
  Tilting modules over commutative rings were recently classified in [12]: they
correspond bijectively to faithful Gabriel topologies of finite type. In this
note we extend this classification by dropping faithfulness. The counterpart of
an arbitrary Gabriel topology of finite type is obtained by replacing tilting
with the more general notion of a silting module.


title: Quantum Flywheel

abstract:
  A quantum flywheel is studied with the purpose of storing useful work in
quantum levels, while additional power is extracted continuously from the
device. The flywheel gains its energy form a quantum heat engine. Generally,
when a work repository is quantized the work exchange with the engine is
accompanied with heat exchange, which may degrade the charging efficiency. In
the particular realization of a quantum harmonic oscillator work repository,
quantum and thermal fluctuations dominates the dynamics. Quantum monitoring and
feedback control are applied to the flywheel, as it is shown to be an essential
part of stabilizing and regulating its state of operation, and bringing the
system to a steady state. A particular balance between information gained by
measuring the system and the information fed back to the system is found to
maximize the charging efficiency. The dynamics of the flywheel are described by
a stochastic master equation that accounts for the engine, the external
driving, the measurement, and the feedback operations.


title:
Local conservative regularizations of compressible magnetohydrodynamic
  and neutral flows

abstract:
  Ideal systems like MHD and Euler flow may develop singularities in vorticity
(w = curl v). Viscosity and resistivity provide dissipative regularizations of
the singularities. In this paper we propose a minimal, local, conservative,
nonlinear, dispersive regularization of compressible flow and ideal MHD, in
analogy with the KdV regularization of the 1D kinematic wave equation. This
work extends and significantly generalizes earlier work on incompressible Euler
and ideal MHD. It involves a micro-scale cutoff length lambda which is a
function of density, unlike in the incompressible case. In MHD, it can be taken
to be of order the electron collisionless skin depth c/omega_pe. Our
regularization preserves the symmetries of the original systems, and with
appropriate boundary conditions, leads to associated conservation laws. Energy
and enstrophy are subject to a priori bounds determined by initial data in
contrast to the unregularized systems. A Hamiltonian and Poisson bracket
formulation is developed and applied to generalize the constitutive relation to
bound higher moments of vorticity. A `swirl' velocity field is identified, and
shown to transport w/rho and B/rho, generalizing the Kelvin-Helmholtz and
Alfven theorems. The steady regularized equations are used to model a rotating
vortex, MHD pinch and a plane vortex sheet. The proposed regularization could
facilitate numerical simulations of fluid/MHD equations and provide a
consistent statistical mechanics of vortices/current filaments in 3D, without
blowup of enstrophy. Implications for detailed analyses of fluid and plasma
dynamic systems arising from our work are briefly discussed.

categories: physics.plasm-ph math-ph math.MP physics.flu-dyn


title: Monads on dagger categories

abstract:
  The theory of monads on categories equipped with a dagger (a contravariant
identity-on-objects involutive endofunctor) works best when everything respects
the dagger: the monad and adjunctions should preserve the dagger, and the monad
and its algebras should satisfy the so-called Frobenius law. Then any monad
resolves as an adjunction, with extremal solutions given by the categories of
Kleisli and Frobenius-Eilenberg-Moore algebras, which again have a dagger. We
characterize the Frobenius law as a coherence property between dagger and
closure, and characterize strong such monads as being induced by Frobenius
monoids.


title:
A L\'evy-Khinchin Formula for the Space of Infinite Dimensional Square
  Complex Matrices

abstract:
  Using a generalised Bochner type representation for Olshanski spherical
pairs, we establish a L\'evy-Khinchin formula for the continuous functions of
negative type on the space $V_\infty= M(\infty, \mathbb C)$ of infinite
dimensional square complex matrices relatively to the action of the product
group $K_\infty=U(\infty)\times U(\infty)$. The space $V_\infty$ is the
inductive limit of the spaces $V_n=M(n, \mathbb C)$, and the group $K_\infty$
is the inductive limit of the product groups $K_n=U(n)\times U(n)$, where
$U(n)$ is the unitary group.


title:
On Hardy-Littlewood-type and Hausdorff-Young-type inequalities for
  generalized Gegenbauer expansions

abstract:
  Using well-known techniques, we establish Hardy-Littlewood-type and
Hausdorff-Young-type inequalities for generalized Gegenbauer expansions and
their unification.


title:
Point counting on $K3$ surfaces and an application concerning real and
  complex multiplication

abstract:
  We report on our project to find explicit examples of $K3$ surfaces having
real or complex multiplication. Our strategy is to search through the
arithmetic consequences of RM and CM. In order to do this, an efficient method
is needed for point counting on surfaces defined over finite fields. For this,
we describe algorithms that are $p$-adic in nature.


title: Dimension and codimension of simple games

abstract:
  This paper studies the complexity of computing a representation of a simple
game as the intersection (union) of weighted majority games, as well as, the
dimension or the codimension. We also present some examples with linear
dimension and exponential codimension with respect to the number of players.


title: Diffusion leaky LMS algorithm: analysis and implementation

abstract:
  The diffusion least-mean square (dLMS) algorithms have attracted much
attention owing to its robustness for distributed estimation problems. However,
the performance of such filters may change when they are implemented for
suppressing noises from speech signals. To overcome this problem, a diffusion
leaky dLMS algorithm is proposed in this work, which is characterized by its
numerical stability and small misadjustment for noisy speech signals when the
unknown system is a lowpass filter. Finally, two implementations of the leaky
dLMS are introduced. It is demonstrated that the leaky dLMS can be effectively
introduced into a noise reduction network for speech signals.


title: Manifolds of Projective Shapes

abstract:
  The projective shape of a configuration of k points or "landmarks" in RP(d)
consists of the information that is invariant under projective transformations
and hence is reconstructable from uncalibrated camera views. Mathematically,
the space of projective shapes for these k landmarks can be described as the
quotient space of k copies of RP(d) modulo the action of the projective linear
group PGL(d). Using homogeneous coordinates, such configurations can be
described as real k-times-(d+1)-dimensional matrices given up to
left-multiplication of non-singular diagonal matrices, while the group PGL(d)
acts as GL(d+1) from the right. The main purpose of this paper is to give a
detailed examination of the topology of projective shape space, and, using
matrix notation, it is shown how to derive subsets that are in a certain sense
maximal, differentiable Hausdorff manifolds which can be provided with a
Riemannian metric. A special subclass of the projective shapes consists of the
Tyler regular shapes, for which geometrically motivated pre-shapes can be
defined, thus allowing for the construction of a natural Riemannian metric.


title: Generalized roll-call model for the Shapley-Shubik index

abstract:
  In 1996 Dan Felsenthal and Mosh\'e Machover considered the following model.
An assembly consisting of $n$ voters exercises roll-call. All $n!$ possible
orders in which the voters may be called are assumed to be equiprobable. The
votes of each voter are independent with expectation $0<p<1$ for an individual
vote {\lq\lq}yea{\rq\rq}. For a given decision rule $v$ the \emph{pivotal}
voter in a roll-call is the one whose vote finally decides the aggregated
outcome. It turned out that the probability to be pivotal is equivalent to the
Shapley-Shubik index. Here we give an easy combinatorial proof of this
coincidence, further weaken the assumptions of the underlying model, and study
generalizations to the case of more than two alternatives.


title: MIDAS: Lessons learned from the first spaceborne atomic force microscope

abstract:
  The Micro-Imaging Dust Analysis System (MIDAS) atomic force microscope (AFM)
onboard the Rosetta orbiter was the first such instrument launched into space
in 2004. Designed only a few years after the technique was invented, MIDAS is
currently orbiting comet 67P Churyumov-Gerasimenko and producing the highest
resolution 3D images of cometary dust ever made in situ. After more than a year
of continuous operation much experience has been gained with this novel
instrument. Coupled with operations of the Flight Spare and advances in
terrestrial AFM a set of "lessons learned" has been produced, cumulating in
recommendations for future spaceborne atomic force microscopes. The majority of
the design could be reused as-is, or with incremental upgrades to include more
modern components (e.g. the processor). Key additional recommendations are to
incorporate an optical microscope to aid the search for particles and image
registration, to include a variety of cantilevers (with different spring
constants) and a variety of tip geometries.


title:
Numerical studies of the scattering of light from a two-dimensional
  randomly rough interface between two dielectric media

abstract:
  The scattering of polarized light incident from one dielectric medium on its
two-dimensional randomly rough interface with a second dielectric medium is
studied. A reduced Rayleigh equation for the scattering amplitudes is derived
for the case where p- or s-polarized light is incident on this interface, with
no assumptions being made regarding the dielectric functions of the media.
Rigorous, purely numerical, nonperturbative solutions of this equation are
obtained. They are used to calculate the reflectivity and reflectance of the
interface, the mean differential reflection coefficient, and the full angular
distribution of the intensity of the scattered light. These results are
obtained for both the case where the medium of incidence is the optically less
dense medium, and in the case where it is the optically more dense medium.
Optical analogues of the Yoneda peaks observed in the scattering of x-rays from
metal surfaces are present in the results obtained in the latter case. Brewster
scattering angles for diffuse scattering are investigated, reminiscent of the
Brewster angle for flat-interface reflection, but strongly dependent on the
angle of incidence. When the contribution from the transmitted field is added
to that from the scattered field it is found that the results of these
calculations satisfy unitarity with an error smaller than $10^{-4}$.


title:
Search for R-parity violating decays of a top squark in proton-proton
  collisions at sqrt(s) = 8 TeV

abstract:
  The results of a search for a supersymmetric partner of the top quark (top
squark), pair-produced in proton-proton collisions at sqrt(s) = 8 TeV, are
presented. The search, which focuses on R-parity violating, chargino-mediated
decays of the top squark, is performed in final states with low missing
transverse momentum, two oppositely charged electrons or muons, and at least
five jets. The analysis uses a data sample corresponding to an integrated
luminosity of 19.7 inverse femtobarns collected with the CMS detector at the
LHC in 2012. The data are found to be in agreement with the standard model
expectation, and upper limits are placed on the top squark pair production
cross section at 95% confidence level. Assuming a 100% branching fraction for
the top squark decay chain, top squark to t + chargino, chargino to lepton +
jj, top squark masses less than 890 (1000) GeV for the electron (muon) channel
are excluded for the first time in models with a single nonzero R-parity
violating coupling lambda'[ijk] (i,j,k <= 2), where i,j,k correspond to the
three generations.


title: Learning Over Long Time Lags

abstract:
  The advantage of recurrent neural networks (RNNs) in learning dependencies
between time-series data has distinguished RNNs from other deep learning
models. Recently, many advances are proposed in this emerging field. However,
there is a lack of comprehensive review on memory models in RNNs in the
literature. This paper provides a fundamental review on RNNs and long short
term memory (LSTM) model. Then, provides a surveys of recent advances in
different memory enhancements and learning techniques for capturing long term
dependencies in RNNs.


title: Discrete Directional Gabor Frames

abstract:
  We develop a theory of discrete directional Gabor frames for functions
defined on the $d$-dimensional Euclidean space. Our construction incorporates
the concept of ridge functions into the theory of isotropic Gabor systems, in
order to develop an anisotropic Gabor system with strong directional
sensitivity. We present sufficient conditions on a window function $g$ and a
sampling set $\Lambda$ for the corresponding directional Gabor system
$\{g_{m,t,u}\}_{(m,t,u)\in\Lambda}$ to form a discrete frame. Explicit
estimates on the frame bounds are developed. A numerical implementation of our
scheme is also presented, and is shown to perform competitively in compression
and denoising against state-of-the-art anisotropic methods.


title:
Tighter bounds on a hypothetical graviton screening mass from the
  gravitational wave observation GW150914 at LIGO

abstract:
  While quantum gravity is not solved yet, a screening mass for the graviton
remains theoretically possible. If such a mass would screen gravity at
distances of the order of the cluster galaxy radius, it could account for the
universe expansion. The modified Newtonian dynamics model also could be related
to a screening graviton mass at inter-galactic scales. Moreover, massive spin-2
theories constitute a very active theoretical topic. We briefly show how the
very recent LIGO gravitational wave observation GW150914, emitted by a binary
black hole merger distant $\sim 1.3 \times 10^9$ ly from the Earth, tightens
the phenomenological bound on a massive graviton or on the screening of
gravity.


title: Capture cross sections of 15N(n, {\gamma})16N at astrophysical energies

abstract:
  We have reanalyzed reaction cross sections of 16N on 12C target. The nucleon
density distribution of 16N, especially surface density distribution, was
extracted using the modified Glauber model. On the basis of dilute surface
densities, the discussion of 15N(n, {\gamma})16N reaction was performed within
the framework of the direct capture reaction mechanism. The calculations agreed
quite well with the experimental data.


title: Mathematical Theory Exploration in Theorema: Reduction Rings

abstract:
  In this paper we present the first-ever computer formalization of the theory
of Gr\"obner bases in reduction rings, which is an important theory in
computational commutative algebra, in Theorema. Not only the formalization, but
also the formal verification of all results has already been fully completed by
now; this, in particular, includes the generic implementation and correctness
proof of Buchberger's algorithm in reduction rings. Thanks to the seamless
integration of proving and computing in Theorema, this implementation can now
be used to compute Gr\"obner bases in various different domains directly within
the system. Moreover, a substantial part of our formalization is made up solely
by "elementary theories" such as sets, numbers and tuples that are themselves
independent of reduction rings and may therefore be used as the foundations of
future theory explorations in Theorema.
  In addition, we also report on two general-purpose Theorema tools we
developed for an efficient and convenient exploration of mathematical theories:
an interactive proving strategy and a "theory analyzer" that already proved
extremely useful when creating large structured knowledge bases.


title:
Tomorrow's Metamaterials: Manipulation of Electromagnetic Waves in
  Space, Time and Spacetime

abstract:
  Metamaterials represent one of the most vibrant fields of modern science and
technology. They are generally dispersive structures in the direct and
reciprocal space and time domains. Upon this consideration, I overview here a
number of metamaterial innovations developed by colleagues and myself in the
holistic framework of space and time dispersion engineering. Moreover, I
provide some thoughts regarding the future perspectives of the area.


title: Attention-Based Convolutional Neural Network for Machine Comprehension

abstract:
  Understanding open-domain text is one of the primary challenges in natural
language processing (NLP). Machine comprehension benchmarks evaluate the
system's ability to understand text based on the text content only. In this
work, we investigate machine comprehension on MCTest, a question answering (QA)
benchmark. Prior work is mainly based on feature engineering approaches. We
come up with a neural network framework, named hierarchical attention-based
convolutional neural network (HABCNN), to address this task without any
manually designed features. Specifically, we explore HABCNN for this task by
two routes, one is through traditional joint modeling of passage, question and
answer, one is through textual entailment. HABCNN employs an attention
mechanism to detect key phrases, key sentences and key snippets that are
relevant to answering the question. Experiments show that HABCNN outperforms
prior deep learning approaches by a big margin.


title:
Towards room-temperature superfluidity of exciton polaritons in an
  optical microcavity with an embedded MoS$_2$ monolayer

abstract:
  By considering driven diffusive dynamics of exciton polaritons in an optical
microcavity with an embedded molybdenum disulfide monolayer, we determine
experimentally relevant range of parameters at which room-temperature
superfuidity can be observed. It is shown that the superfluid transitions
occurs in a trapped polariton gas at laser pumping power $P>600$ mW and and
trapping potential strength $k > 50$ eV/cm$^2$. We also propose a simple
analytic model that provides a useful estimate for the polariton gas density,
which enables one to determine the conditions for observation of room
temperature polariton superfluidity.


title:
Automorphisms of algebras and Bochner`s property for discrete vector
  orthogonal polynomials

abstract:
  We construct new families of discrete vector orthogonal polynomials that have
the property to be eigenfunctions of some difference operator. They are
extensions of Charlier, Meixner and Kravchuk polynomial systems. The ideas
behind our approach lie in the studies of bispectral operators. We exploit
automorphisms of associative algebras which transform elementary (vector)
orthogonal polynomial systems which are eigenfunctions of a difference operator
into other systems of this type. While the extension of Charlier polynomilas is
well known it is obtained by different methods. The extension of Meixner
polynomial system is new.


title:
Decoupling and tuning competing effects of different types of defects on
  flux creep in irradiated YBa$_{2}$Cu$_{3}$O$_{7-{\delta}}$ coated conductors

abstract:
  YBa$_{2}$Cu$_{3}$O$_{7-{\delta}}$ coated conductors (CCs) have achieved high
critical current densities ($\textit{J}_{c}$) that can be further increased
through the introduction of additional defects using particle irradiation.
However, these gains are accompanied by increases in the flux creep rate, a
manifestation of competition between the different types of defects. Here, we
study this competition to better understand how to design pinning landscapes
that simultaneously increase $\textit{J}_{c}$ and reduce creep. CCs grown by
metal organic deposition show non-monotonic changes in the
temperature-dependent creep rate, $\textit{S}(\textit{T})$. Notably, in low
fields, there is a conspicuous dip to low $\textit{S}$ as temperature
($\textit{T}$) increases from ~20 K to ~65 K. Oxygen-, proton-, and
Au-irradiation substantially increase $\textit{S}$ in this temperature range.
Focusing on an oxygen-irradiated CC, we investigate the contribution of
different types of irradiation-induced defects to the flux creep rate.
Specifically, we study $\textit{S}(\textit{T})$ as we tune the relative density
of point defects to larger defects by annealing both an as-grown and an
irradiated CC in O$_{2}$ at temperatures $\textit{T}_{A}$ = 250${\deg}$C to
600${\deg}$C. We observe a steady decrease in $\textit{S}$($\textit{T}$ > 20 K)
with increasing $\textit{T}_{A}$, unveiling the role of pre-existing
nanoparticle precipitates in creating the dip in $\textit{S}(\textit{T})$ and
point defects and clusters in increasing $\textit{S}$ at intermediate
temperatures.


title:
Robust Transmission in Downlink Multiuser MISO Systems: A Rate-Splitting
  Approach

abstract:
  We consider a downlink multiuser MISO system with bounded errors in the
Channel State Information at the Transmitter (CSIT). We first look at the
robust design problem of achieving max-min fairness amongst users (in the
worst-case sense). Contrary to the conventional approach adopted in literature,
we propose a rather unorthodox design based on a Rate-Splitting (RS) strategy.
Each user's message is split into two parts, a common part and a private part.
All common parts are packed into one super common message encoded using a
public codebook, while private parts are independently encoded. The resulting
symbol streams are linearly precoded and simultaneously transmitted, and each
receiver retrieves its intended message by decoding both the common stream and
its corresponding private stream. For CSIT uncertainty regions that scale with
SNR (e.g. by scaling the number of feedback bits), we prove that a RS-based
design achieves higher max-min (symmetric) Degrees of Freedom (DoF) compared to
conventional designs (NoRS). For the special case of non-scaling CSIT (e.g.
fixed number of feedback bits), and contrary to NoRS, RS can achieve a
non-saturating max-min rate. We propose a robust algorithm based on the
cutting-set method coupled with the Weighted Minimum Mean Square Error (WMMSE)
approach, and we demonstrate its performance gains over state-of-the art
designs. Finally, we extend the RS strategy to address the Quality of Service
(QoS) constrained power minimization problem, and we demonstrate significant
gains over NoRS-based designs.


title:
Spacetime Processing Metasurfaces: GSTC Synthesis and Prospective
  Applications

abstract:
  The paper presents the general concept of spacetime processing metasurfaces,
synthesized by generalized sheet transition conditions (GSTCs). It is shown
that such metasurfaces can perform multiple simultaneous spatio-temporal
processing transformations on incident electromagnetic waves. A time-reversal
space-generalized-refraction metasurface and a multi-time-space-differentiating
metasurfaces are presented as applications of the general spacetime processing
metasurface concept.


title: Sums of powers of Catalan triangle numbers

abstract:
  In this paper we consider combinatorial numbers $C_{m, k}$ for $m\ge 1$ and
$k\ge 0$ which unifies the entries of the Catalan triangles $ B_{n, k}$ and $
A_{n, k}$ for appropriate values of parameters $m$ and $k$, i.e., $B_{n,
k}=C_{2n,n-k}$ and $A_{n, k}=C_{2n+1,n+1-k}$. In fact, some of these numbers
are the well-known Catalan numbers $C_n$ that is $C_{2n,n-1}=C_{2n+1,n}=C_n$.
  We present new identities for recurrence relations, linear sums and
alternating sum of $C_{m,k}$. After that, we check sums (and alternating sums)
of squares and cubes of $C_{m,k}$ and, consequently, for $ B_{n, k}$ and $
A_{n, k}$. In particular, one of these equalities solves an open problem posed
in \cite{[GHMN]}. We also present some linear identities involving harmonic
numbers $H_n$ and Catalan triangles numbers $C_{m,k}$. Finally, in the last
section new open problems and identities involving $C_n$ are conjectured.


title: Character Proposal Network for Robust Text Extraction

abstract:
  Maximally stable extremal regions (MSER), which is a popular method to
generate character proposals/candidates, has shown superior performance in
scene text detection. However, the pixel-level operation limits its capability
for handling some challenging cases (e.g., multiple connected characters,
separated parts of one character and non-uniform illumination). To better
tackle these cases, we design a character proposal network (CPN) by taking
advantage of the high capacity and fast computing of fully convolutional
network (FCN). Specifically, the network simultaneously predicts characterness
scores and refines the corresponding locations. The characterness scores can be
used for proposal ranking to reject non-character proposals and the refining
process aims to obtain the more accurate locations. Furthermore, considering
the situation that different characters have different aspect ratios, we
propose a multi-template strategy, designing a refiner for each aspect ratio.
The extensive experiments indicate our method achieves recall rates of 93.88%,
93.60% and 96.46% on ICDAR 2013, SVT and Chinese2k datasets respectively using
less than 1000 proposals, demonstrating promising performance of our character
proposal network.


title:
Coupled gyration modes and propagation in one-dimensional periodic
  skyrmion arrays as reliable information carrier

abstract:
  We report on a micromagnetic numerical simulation study of dynamic couplings
between neighboring skyrmions in narrow-width nanostrips. We explored the
coupled gyration modes and their characteristic dispersions in terms of the
interdistance between the neighboring skyrmions. The application of
perpendicular magnetic fields, importantly, allows for control/modification of
the dispersion of the coupled modes. Coupled skyrmion gyration modes provide a
new type of efficient, reliable, fast, low-power-consumption information-signal
propagation in narrow-width straight and curved nanostrips, as driven
predominantly by the exchange interaction between individual nano-scale
skyrmions.


title: Lower bound of assortativity coefficient in scale-free networks

abstract:
  The degree-degree correlation is important in understanding the structural
organization of a network and the dynamics upon a network. Such correlation is
usually measured by the assortativity coefficient $r$, with natural bounds $r
\in [-1,1]$. For scale-free networks with power-law degree distribution $p(k)
\sim k^{-\gamma}$, we analytically obtain the lower bound of assortativity
coefficient in the limit of large network size, which is not -1 but dependent
on the power-law exponent $\gamma$. This work challenges the validation of
assortativity coefficient in heterogeneous networks, suggesting that one cannot
judge whether a network is positively or negatively correlated just by looking
at its assortativity coefficient.


title: Multiplicative Zagreb indices of k-trees

abstract:
  Let G be a graph with vertex set V (G) and edge set E(G). The first
generalized multiplicative Zagreb index of G is M_1(G) and the second
multiplicative Zagreb index is M_2(G). The multiplicative Zagreb indices have
been the focus of considerable research in computational chemistry dating back
to Narumi and Katayama in 1980s. In this paper, we generalize Narumi-Katayama
index and the first multiplicative index, where c = 1, 2, respectively, and
extend the results of Gutman to the generalized tree, the k-tree, where the
results of Gutman are for k = 1. Additionally, we characterize the extremal
graphs and determine the exact bounds of these indices of k-trees, which attain
the lower and upper bounds.


title:
On the topologic structure of economic complex networks: Empirical
  evidence from large scale payment network of Estonia

abstract:
  This paper presents the first topological analysis of the economic structure
of an entire country based on payments data obtained from Swedbank. This data
set is exclusive in its kind because around 80% of Estonia's bank transactions
are done through Swedbank, hence, the economic structure of the country can be
reconstructed. Scale-free networks are commonly observed in a wide array of
different contexts such as nature and society. In this paper, the nodes are
comprised by customers of the bank (legal entities) and the links are
established by payments between these nodes. We study the scaling-free and
structural properties of this network. We also describe its topology,
components and behaviors. We show that this network shares typical structural
characteristics known in other complex networks: degree distributions follow a
power law, low clustering coefficient and low average shortest path length. We
identify the key nodes of the network and perform simulations of resiliency
against random and targeted attacks of the nodes with two different approaches.
With this, we find that by identifying and studying the links between the nodes
is possible to perform vulnerability analysis of the Estonian economy with
respect to economic shocks.


title:
The algebraic dichotomy conjecture for infinite domain Constraint
  Satisfaction Problems

abstract:
  We prove that an $\omega$-categorical core structure primitively positively
interprets all finite structures with parameters if and only if some stabilizer
of its polymorphism clone has a homomorphism to the clone of projections, and
that this happens if and only if its polymorphism clone does not contain
operations $\alpha$, $\beta$, $s$ satisfying the identity $\alpha
s(x,y,x,z,y,z) \approx \beta s(y,x,z,x,z,y)$.
  This establishes an algebraic criterion equivalent to the conjectured
borderline between P and NP-complete CSPs over reducts of finitely bounded
homogenous structures, and accomplishes one of the steps of a proposed strategy
for reducing the infinite domain CSP dichotomy conjecture to the finite case.
  Our theorem is also of independent mathematical interest, characterizing a
topological property of any $\omega$-categorical core structure (the existence
of a continuous homomorphism of a stabilizer of its polymorphism clone to the
projections) in purely algebraic terms (the failure of an identity as above).


title: Dimension invariants of outer automorphism groups

abstract:
  The geometric dimension for proper actions $\underline{\mathrm{gd}}(G)$ of a
group $G$ is the minimal dimension of a classifying space for proper actions
$\underline{E}G$. We construct for every integer $r\geq 1$, an example of a
virtually torsion-free Gromov-hyperbolic group $G$ such that for every group
$\Gamma$ which contains $G$ as a finite index normal subgroup, the virtual
cohomological dimension $\mathrm{vcd}(\Gamma)$ of $\Gamma $ equals
$\underline{\mathrm{gd}}(\Gamma)$ but such that the outer automorphism group
$\mathrm{Out}(G)$ is virtually torsion-free, admits a cocompact model for
$\underline E\mathrm{Out}(G)$ but nonetheless has
$\mathrm{vcd}(\mathrm{Out}(G))\le\underline{\mathrm{gd}}(\mathrm{Out}(G))-r$.


title:
Transverse foliations on the torus $\T^2$ and partially hyperbolic
  diffeomorphisms on 3-manifolds

abstract:
  In this paper, we prove that given two $C^1$ foliations $\mathcal{F}$ and
$\mathcal{G}$ on $\mathbb{T}^2$ which are transverse, there exists a non-null
homotopic loop $\{\Phi_t\}_{t\in[0,1]}$ in $\diff^{1}(\T^2)$ such that
$\Phi_t(\calF)\pitchfork \calG$ for every $t\in[0,1]$, and $\Phi_0=\Phi_1= Id$.
As a direct consequence, we get a general process for building new partially
hyperbolic diffeomorphisms on closed $3$-manifolds. \cite{BPP} built a new
example of dynamically coherent non-transitive partially hyperbolic
diffeomorphism on a closed $3$-manifold, the example in \cite{BPP} is obtained
by composing the time $t$ map, $t>0$ large enough, of a very specific
non-transitive Anosov flow by a Dehn twist along a transverse torus. Our result
shows that the same construction holds starting with any non-transitive Anosov
flow on an oriented $3$-manifold. Moreover, for a given transverse torus, our
result explains which type of Dehn twists lead to partially hyperbolic
diffeomorphisms.


title: Reabsorption of nonequilibrium phonons at superconducting point contacts

abstract:
  When there is a deviation from the inequality $d\ll {{l}_{\varepsilon }}$
($d$ is the contact diameter, and ${{l}_{\varepsilon }}$ is the energy
relaxation length of the electrons), structural features are produced on the
current-voltage characteristics of $S-c-N$ contacts at characteristic phonon
energies because of the decrease in $\Delta $ due to the accumulation of
nonequilibrium phonons with low group velocities near the contact.


title:
Towards a Molecular Level Understanding of the Sulfanilamide-Soil
  Organic Matter-Interaction

abstract:
  In-depth understanding of the sorption mechanisms of organic pollutants, like
the antibiotic sulfanilamide (SAA), in soil requires a combined experimental
and theoretical approach. Therefore, sorption experiments of SAA on
well-characterized samples of soil size-fractions were combined with the
modeling of SAA-soil-interaction via quantum chemical calculations. Freundlich
unit capacities were determined in batch experiments and it was found that they
increase with the soil organic matter (SOM) content according to the order fine
silt > medium silt > clay > whole soil > coarse silt > sand. The calculated
binding energies for mass-spectrometrically quantified sorption sites followed
the order ionic species > peptides > carbohydrates > phenols and lignin
monomers > lignin dimers > heterocyclic compounds > fatty acids > sterols >
aromatic compounds > lipids, alkanes, and alkenes. SAA forms H-bonds through
its different polar centers with polar SOM sorption sites. In contrast
dispersion and {\pi}-{\pi}-interactions predominate the interaction of the
sulfonamide aromatic ring with the non-polar moieties of SOM. Moreover, the
dipole moment, partial atomic charges, and molecular volume of the SOM sorption
sites are the main physical properties controlling the SAA-SOM-interaction. The
correlation between experimental and theoretical results was established by
reasonable estimates of the Freundlich unit capacities from the calculated
binding energies. Consequently, we suggest using this approach in forthcoming
studies to disclose the interactions of a wide range of organic pollutants with
SOM.


title: Machine olfaction using time scattering of sensor multiresolution graphs

abstract:
  In this paper we construct a learning architecture for high dimensional time
series sampled by sensor arrangements. Using a redundant wavelet decomposition
on a graph constructed over the sensor locations, our algorithm is able to
construct discriminative features that exploit the mutual information between
the sensors. The algorithm then applies scattering networks to the time series
graphs to create the feature space. We demonstrate our method on a machine
olfaction problem, where one needs to classify the gas type and the location
where it originates from data sampled by an array of sensors. Our experimental
results clearly demonstrate that our method outperforms classical machine
learning techniques used in previous studies.


title: Log-behavior of two sequences related to the elliptic integrals

abstract:
  Two interesting sequences arose in the study of the series expansions of the
complete elliptic integrals, which are called the Catalan-Larcombe-French
sequence $\{P_n\}_{n\geq 0}$ and the Fennessey-Larcombe-French sequence
$\{V_n\}_{n\geq 0}$ respectively. In this paper, we prove the log-convexity of
$\{V_n^2-V_{n-1}V_{n+1}\}_{n\geq 2}$ and $\{n!V_n\}_{n\geq 1}$, the ratio
log-concavity of $\{P_n\}_{n\geq 0}$ and the sequence $\{A_n\}_{n\geq 0}$ of
Ap\'{e}ry numbers, and the ratio log-convexity of $\{V_n\}_{n\geq 1}$.


title:
Smooth projective varieties with a torus action of complexity 1 and
  Picard number 2

abstract:
  We give an explicit description of all smooth varieties with a torus action
of complexity one having Picard number at most two. As a consequence, we
classify in every dimension the smooth (almost) Fano varieties with a torus
action of complexity one having Picard number two. It turns out that all the
Fano examples are obtained via an iterated generalized cone construction from a
series of smooth varieties of dimension at most seven.


title: Minimax Estimation of Kernel Mean Embeddings

abstract:
  In this paper, we study the minimax estimation of the Bochner integral
$$\mu_k(P):=\int_{\mathcal{X}} k(\cdot,x)\,dP(x),$$ also called as the kernel
mean embedding, based on random samples drawn i.i.d.~from $P$, where
$k:\mathcal{X}\times\mathcal{X}\rightarrow\mathbb{R}$ is a positive definite
kernel. Various estimators (including the empirical estimator),
$\hat{\theta}_n$ of $\mu_k(P)$ are studied in the literature wherein all of
them satisfy $\bigl\|
\hat{\theta}_n-\mu_k(P)\bigr\|_{\mathcal{H}_k}=O_P(n^{-1/2})$ with
$\mathcal{H}_k$ being the reproducing kernel Hilbert space induced by $k$. The
main contribution of the paper is in showing that the above mentioned rate of
$n^{-1/2}$ is minimax in $\|\cdot\|_{\mathcal{H}_k}$ and
$\|\cdot\|_{L^2(\mathbb{R}^d)}$-norms over the class of discrete measures and
the class of measures that has an infinitely differentiable density, with $k$
being a continuous translation-invariant kernel on $\mathbb{R}^d$. The
interesting aspect of this result is that the minimax rate is independent of
the smoothness of the kernel and the density of $P$ (if it exists). This result
has practical consequences in statistical applications as the mean embedding
has been widely employed in non-parametric hypothesis testing, density
estimation, causal inference and feature selection, through its relation to
energy distance (and distance covariance).


title:
Inferring asymmetric limb cloudiness on exoplanets from transit light
  curves

abstract:
  Clouds have been shown to be present in many exoplanetary atmospheres. Cloud
formation modeling predicts considerable inhomogeneities of cloud cover,
consistent with optical phase curve observations. However, optical phase curves
cannot resolve some existing degeneracies between cloud location and cloud
optical properties.
  We present a conceptually simple technique to detect inhomogeneous cloud
cover on exoplanets. Such an inhomogeneous cloud cover produces an asymmetric
primary transit of the planet in front of the host star. Asymmetric transits
produce characteristic residuals compared to a standard symmetric model.
Furthermore, bisector spans can be used to determine asymmetries in the transit
light curve.
  We apply a model of asymmetric transits to the light curves of HAT-P-7b,
Kepler-7b and HD209458b and search for possible cloud signatures. The nearly
uninterrupted Kepler photometry is particularly well-suited for this method
since it allows for a very high time resolution.
  We do not find any statistically sound cloud signature in the data of the
considered planets. For HAT-P-7b, a tentative detection of an asymmetric cloud
cover is found, consistent with analysis of the optical phase curve. Based on
Bayesian probability arguments, a symmetric model with an offset in the transit
ephemeris remains, however, the most viable model. Still, this work
demonstrates that for suitable targets, namely low-gravity planets around
bright stars, the method can be used to constrain cloud cover characteristics
and is thus a helpful additional tool to study exoplanetary atmospheres.


title: Path probability of stochastic motion: A functional approach

abstract:
  The path probability of a particle undergoing stochastic motion is studied by
the use of functional technique, and the general formula is derived for the
path probability distribution functional. The probability of finding paths
inside a tube/band, the center of which is stipulated by a given path, is
analytically evaluated in a way analogous to continuous measurements in quantum
mechanics. Then, the formalism developed here is applied to the stochastic
dynamics of stock price in finance.


title: Look, Listen and Learn - A Multimodal LSTM for Speaker Identification

abstract:
  Speaker identification refers to the task of localizing the face of a person
who has the same identity as the ongoing voice in a video. This task not only
requires collective perception over both visual and auditory signals, the
robustness to handle severe quality degradations and unconstrained content
variations are also indispensable. In this paper, we describe a novel
multimodal Long Short-Term Memory (LSTM) architecture which seamlessly unifies
both visual and auditory modalities from the beginning of each sequence input.
The key idea is to extend the conventional LSTM by not only sharing weights
across time steps, but also sharing weights across modalities. We show that
modeling the temporal dependency across face and voice can significantly
improve the robustness to content quality degradations and variations. We also
found that our multimodal LSTM is robustness to distractors, namely the
non-speaking identities. We applied our multimodal LSTM to The Big Bang Theory
dataset and showed that our system outperforms the state-of-the-art systems in
speaker identification with lower false alarm rate and higher recognition
accuracy.


title: The triangle scheduling problem

abstract:
  This paper introduces a novel scheduling problem, where jobs occupy a
triangular shape on the time line. This problem is motivated by scheduling jobs
with different criticality levels. A measure is introduced, namely the binary
tree ratio. It is shown that the greedy algorithm solves the problem to
optimality when the binary tree ratio of the input instance is at most 2. We
also show that the problem is unary NP-hard for instances with binary tree
ratio strictly larger than 2, and provide a quasi polynomial time approximation
scheme (QPTAS). The approximation ratio of Greedy on general instances is shown
to be between 1.5 and 1.05.


title: Effective Mass in Rosenbluth-Hinton type zonal flows

abstract:
  An initial radial electric field, $E_r(0)$, in an axisymmetric tokamak,
results in geodesic acoustic mode (GAM) oscillations. The GAMs Landau damp,
resulting in a much smaller final residual electric field, $E_r(\infty)$, and
accompanying parallel zonal flows (Rosenbluth and Hinton, 1998 PRL 80, 724,
hereafter RH). The phenomenon exhibits a large effective mass (inertia due to
flows), with an enhancement of order the well-known RH factor. In apparent
paradox, the final angular momentum in the RH parallel zonal flow is much
smaller than the angular momentum expected from the well-known rapid precession
of the trapped particle population in the final electric field. In addition, an
effective mass calculated naively based on the rapid trapped particle (TP)
precession is much larger than the RH factor. A drift kinetic calculation is
presented showing that the mathematical origin of the extra mass factor is a
shift, proportional to $E_r$, of the usual energy coordinates in phase space.
Importantly, this shift contributes to the effective mass even if the system is
linearized in $E_r$, and can be interpreted as a first order linear shift in
the Jacobian. Further, the Jacobian shift recovers the large TP precession flow
and also uncovers the presence of reverse circulating particle flows that, to
lowest order, are equal and opposite to the TP precession. A detailed
calculation is presented. Work supported by DOE.


title:
Single-shot optical readout of a quantum bit using cavity quantum
  electrodynamics

abstract:
  We propose a method to perform single-shot optical readout of a quantum bit
(qubit) using cavity quantum electrodynamics. We selectively couple the optical
transitions associated with different qubit basis states to the cavity, and
utilize the change in cavity transmissivity to generate a qubit readout signal
composed of many photons. We show that this approach enables single-shot
optical readout even when the qubit does not have a good cycling transition
required for standard resonance fluorescence measurements. We calculate the
probability that the measurement detects the correct spin state using the
example of a quantum dot spin under various experimental conditions and
demonstrate that it can exceed 0.99.


title: Fast Computation of the Kinship Coefficients

abstract:
  For families, kinship coefficients are quantifications of the amount of
genetic sharing between a pair of individuals. These coefficients are critical
for understanding the breeding habits and genetic diversity of diploid
populations. Historically, computations of the inbreeding coefficient were used
to prohibit inbred marriages and prohibit breeding of some pairs of pedigree
animals. Such prohibitions foster genetic diversity and help prevent recessive
Mendelian disease at a population level.
  This paper gives the fastest known algorithms for computing the kinship
coefficient of a set of individuals with a known pedigree. The algorithms given
here consider the possibility that the founders of the known pedigree may
themselves be inbred, and they compute the appropriate inbreeding-adjusted
kinship coefficients. The exact kinship algorithm has running-time $O(n^2)$ for
an $n$-individual pedigree. The recursive-cut exact kinship algorithm has
running time $O(s^2m)$ where $s$ is the number of individuals in the largest
segment of the pedigree and $m$ is the number of cuts. The approximate
algorithm has running-time $O(n)$ for an $n$-individual pedigree on which to
estimate the kinship coefficients of $\sqrt{n}$ individuals from $\sqrt{n}$
founder kinship coefficients.


title: Edwards Statistical Mechanics for Jammed Granular Matter

abstract:
  In 1989, Sir Sam Edwards made the visionary proposition to treat jammed
granular materials using a volume ensemble of equiprobable jammed states in
analogy to thermal equilibrium statistical mechanics, despite their inherent
athermal features. Since then, the statistical mechanics approach for jammed
matter has garnered an extraordinary amount of attention by both theorists and
experimentalists. Here, we review a systematic approach to jammed matter based
on the Edwards statistical mechanical ensemble. We discuss the construction of
microcanonical and canonical ensembles based on the volume function, which
replaces the Hamiltonian in jammed systems. The importance of approximation
schemes at various levels is emphasized leading to quantitative predictions for
ensemble averaged quantities such as packing fractions and contact force
distributions. An overview of the phenomenology of jammed states and
experiments, simulations, and theoretical models scrutinizing the strong
assumptions underlying Edwards' approach is given including recent results
suggesting the validity of Edwards ergodic hypothesis for jammed states. A
theoretical framework for packings whose constitutive particles range from
spherical to non-spherical shapes like dimers, polymers, ellipsoids,
spherocylinders or tetrahedra, hard and soft, frictional, frictionless and
adhesive, monodisperse and polydisperse particles in any dimensions is
discussed providing insight into an unifying phase diagram for all jammed
matter. Furthermore, the connection between the Edwards' ensemble of metastable
jammed states and metastability in spin-glasses is established. This highlights
that the packing problem can be understood as a constraint satisfaction problem
for excluded volume and force and torque balance leading to a unifying
framework between the Edwards ensemble of equiprobable jammed states and
out-of-equilibrium spin-glasses.


title: Triangle-independent sets vs. cuts

abstract:
  A set of edges $T$ in a graph $G$ is triangle-independent if $T$ contains at
most one edge from each triangle in $G$. Let $\alpha_1(G)$ denote the maximum
size of the triangle-independent set in $G$, and let $\tau_B(G)$ denote minimum
size of a set $F \subseteq E(G)$ such that $G \setminus F$ is bipartite. We
prove that $$\alpha_1(G) + \tau_B(G) \leq \frac{|V(G)|^2}{4},$$ verifying a
conjecture due to Lehel, and independently Puleo, and a slightly weaker
conjecture of Erd\H{o}s, Gallai and Tuza. Further, we characterize the graphs
which attain the equality.


title:
Superconducting-contact-induced resistance-anomalies in the 3D
  topological insulator Bi2Te3

abstract:
  This study examines the magnetotransport response observed in flakes of the
3D topological insulator (TI) Bi2Te3, including indium superconducting
electrodes, and demonstrates two critical transitions in the magnetoresistive
response with decreasing temperatures below T = 3.4K. The first transition is
attributed to superconductivity in the indium electrodes, and the second
transition, with a critical field exceeding the transition field of indium, is
attributed to a proximity effect at the 2D planar interface of this hybrid
TI/superconductor structure.


title: Local Volatility Models in Commodity Markets and Online Calibration

abstract:
  We introduce a local volatility model for the valuation of options on
commodity futures by using European vanilla option prices. The corresponding
calibration problem is addressed within an online framework, allowing the use
of multiple price surfaces. Since uncertainty in the observation of the
underlying future prices translates to uncertainty in data locations, we
propose a model-based adjustment of such prices that improves reconstructions
and smile adherence. In order to tackle the ill-posedness of the calibration
problem we incorporate a priori information through a judiciously designed
Tikhonov-type regularization. Extensive empirical tests with market as well as
synthetic data are used to demonstrate the effectiveness of the methodology and
algorithms.


title:
Global weak solutions of PDEs for compressible media: A compactness
  criterion to cover new physical situations

abstract:
  This short paper is an introduction of the memoir recently written by the two
authors (see [D.Bresch., P.--E. Jabin, arXiv:1507.04629, (2015)]) which
concerns the resolution of two longstanding problems: Global existence of weak
solutions for compressible Navier-Stokes equations with thermodynamically
unstable pressure and with anisotropic stress tensor. We focus here on a
Stokes-like system which can for instance model flows in a compressible tissue
in biology or in a compressible porous media in petroleum engineering. This
allows us to explain, on a simpler but still relevant and important system, the
tools recently introduced by the authors and to discuss the important results
that have been obtained on the compressible Navier--Stokes equations. It is
finally a real pleasure to dedicate this paper to G. Metivier for his 65's
Birthday. The article will appear in the corresponding special issue, Springer
INdAM-Series, Eds F. Colombini, D. Del Santos, D. Lannes (2016).


title: Dicke Superradiance in Solids

abstract:
  Recent advances in optical studies of condensed matter have led to the
emergence of phenomena that have conventionally been studied in the realm of
quantum optics. These studies have not only deepened our understanding of
light-matter interactions but also introduced aspects of many-body correlations
inherent in optical processes in condensed matter systems. This article is
concerned with superradiance (SR), a profound quantum optical process predicted
by Dicke in 1954. The basic concept of SR applies to a general $N$-body system
where constituent oscillating dipoles couple together through interaction with
a common light field and accelerate the radiative decay of the system. In the
most fascinating manifestation of SR, known as superfluorescence (SF), an
incoherently prepared system of $N$ inverted atoms spontaneously develops
macroscopic coherence from vacuum fluctuations and produces a delayed pulse of
coherent light whose peak intensity $\propto N^2$. Such SF pulses have been
observed in atomic and molecular gases, and their intriguing quantum nature has
been unambiguously demonstrated. Here, we focus on the rapidly developing field
of research on SR in solids, where not only photon-mediated coupling but also
strong Coulomb interactions and ultrafast scattering exist. We describe SR and
SF in molecular centers in solids, molecular aggregates and crystals, quantum
dots, and quantum wells. In particular, we will summarize a series of studies
we have recently performed on quantum wells in strong magnetic fields. These
studies show that cooperative effects in solid-state systems are not merely
small corrections that require exotic conditions to be observed; rather, they
can dominate the nonequilibrium dynamics and light emission processes of the
entire system of interacting electrons.


title: Science Question Answering using Instructional Materials

abstract:
  We provide a solution for elementary science test using instructional
materials. We posit that there is a hidden structure that explains the
correctness of an answer given the question and instructional materials and
present a unified max-margin framework that learns to find these hidden
structures (given a corpus of question-answer pairs and instructional
materials), and uses what it learns to answer novel elementary science
questions. Our evaluation shows that our framework outperforms several strong
baselines.


title: BPCMont: Business Process Change Management Ontology

abstract:
  Change management for evolving collaborative business process development is
crucial when the business logic, transections and workflow change due to
changes in business strategies or organizational and technical environment.
During the change implementation, business processes are analyzed and improved
ensuring that they capture the proposed change and they do not contain any
undesired functionalities or change side-effects. This paper presents Business
Process Change Management approach for the efficient and effective
implementation of change in the business process. The key technology behind our
approach is our proposed Business Process Change Management Ontology (BPCMont)
which is the main contribution of this paper. BPCMont, as a formalized change
specification, helps to revert BP into a consistent state in case of system
crash, intermediate conflicting stage or unauthorized change done, aid in
change traceability in the new and old versions of business processes, change
effects can be seen and estimated effectively, ease for Stakeholders to
validate and verify change implementation, etc.


title: On a problem concerning affine-invariant points of convex sets

abstract:
  This text is a somewhat reformatted (e.g., some statements that were not as
such in the original paper, are given the names "Corollary" or "Theorem.")
translation of the old and practically inaccessible paper: P. Kuchment, On the
question of the affine-invariant points of convex bodies, (in Russian),
Optimizacija No. 8(25) (1972), 48--51, 127. MR0350621. There partial solutions
of some old problems of B. Gr\"unbaum concerning affine-invariant points of
convex bodies were obtained. The main restriction, due to which the solution
was incomplete, was the compactness restriction on the group of linear
transformations involved. It was noticed recently by O. Mordhorst
(arXiv:1601.07850) that a simple additional argument allows one to restrict the
consideration to the bodies whose John's ellipsoid is a ball and consequently
to a compact group case. This in turn extends the result to the complete
solution of B. Gr\"unbaum's problem (see also some partial progress in the
previous recent works by M. Meyer, C. Sch\"utt, and E. Werner).
  The article translated below contains three main statements: existence of
invariant points in the case when the linear parts of affine transformations
are taken from a compact group, the resulting from this proof of B.
Gr\"unbaum's conjecture for the case of similarity invariant points, and an
example precluding the set of all such points from being the convex hull of
finitely many of them.


title:
Centrality dependence of subthreshold $\phi$ meson production in Ni+Ni
  collisions at 1.9A GeV

abstract:
  We analysed the $\phi$ meson production in central Ni+Ni collisions at the
beam kinetic energy of 1.93A GeV with the FOPI spectrometer and found the
production probability per event of $[8.6 ~\pm~ 1.6 ~(\text{stat}) \pm 1.5
~(\text{syst})] \times 10^{-4}$. This new data point allows for the first time
to inspect the centrality dependence of the subthreshold $\phi$ meson
production in heavy-ion collisions. The rise of $\phi$ meson multiplicity per
event with mean number of participants can be parameterized by the power
function with exponent $\alpha = 1.8 \pm 0.6$. The ratio of $\phi$ to
$\text{K}^-$ production yields seems not to depend within the experimental
uncertainties on the collision centrality, and the average of measured values
was found to be $0.36 \pm 0.05$.


title:
Adaptive Filter for Automatic Identification of Multiple Faults in a
  Noisy OTDR Profile

abstract:
  We present a novel methodology able to distinguish meaningful level shifts
from typical signal fluctuations. A two-stage regularization filtering can
accurately identify the location of the significant level-shifts with an
efficient parameter-free algorithm. The developed methodology demands low
computational effort and can easily be embedded in a dedicated processing unit.
Our case studies compare the new methodology with current available ones and
show that it is the most adequate technique for fast detection of multiple
unknown level-shifts in a noisy OTDR profile.


title:
Entanglement entropy of disordered quantum chains following a global
  quench

abstract:
  We numerically investigate the growth of the entanglement entropy S_{ent}(t)
in time t---after a global quench from a product state---in quantum chains with
various kinds of disorder. The main focus is, in particular, on fermionic
chains with bond disorder. In the noninteracting case at criticality we
numerically test recent predictions by the real space renormalization group for
the entanglement growth in time, the maximal entanglement as a function of
block size, and the decay of a density wave order parameter. We show that
multiprecision calculations are required to reach the scaling regime and
perform such calculations for specific cases. For interacting models with
binary bond disorder we present data based on infinite size density matrix
renormalization group calculations and exact diagonalizations. We obtain first
numerical evidence for a many-body localized phase in bond disordered systems
where S_{ent}(t)~ln t$ seems to hold. Our results for bond disorder are
contrasted with the well studied case of potential disorder.


title: Lattice spanners of low degree

abstract:
  Let $\delta_0(P,k)$ denote the degree $k$ dilation of a point set $P$ in the
domain of plane geometric spanners. If $\Lambda$ is the infinite square
lattice, it is shown that $1+\sqrt{2} \leq \delta_0(\Lambda,3) \leq (3+2\sqrt2)
\, 5^{-1/2} = 2.6065\ldots$ and $\delta_0(\Lambda,4) = \sqrt{2}$. If $\Lambda$
is the infinite hexagonal lattice, it is shown that $\delta_0(\Lambda,3) =
1+\sqrt{3}$ and $\delta_0(\Lambda,4) = 2$. All our constructions are planar
lattice tilings constrained to degree $3$ or $4$.


title: A Coinductive Approach to Proof Search through Typed Lambda-Calculi

abstract:
  In reductive proof search, proofs are naturally generalized by solutions,
comprising all possibly infinite structures generated by locally correct,
bottom-up application of inference rules. We propose an extension of the
Curry-Howard paradigm of representation, from proofs to solutions: to represent
solutions by possibly infinite terms of a dedicated lambda-calculus. This new,
comprehensive approach to proof search is exemplified with the sequent calculus
LJT for intuitionistic implication logic. A finitary representation is
proposed, comprising lambda-terms extended with a formal greatest fixed point,
and a type system that can be seen as a logic of coinductive proofs. In the
finitary system, fixed-point variables enjoy a relaxed form of binding that
allows the detection of cycles through the type system. Formal sums are used to
express alternatives in the search process. Moreover, formal sums are used in
the coinductive syntax to define "decontraction" (contraction bottom-up) - an
operation whose theory we initiate in this paper. As a semantics, we assign a
coinductive lambda-term to each finitary term. The main result is the existence
of an equivalent finitary representation for any full solution space expressed
coinductively. This result is the main ingredient in the proof that our logic
of coinductive proofs is sound and complete with respect to the coinductive
semantics. These results are the foundation for an original approach to proof
search, where the search builds the finitary representation of the full
solution space, and the a posteriori analysis typically consisting in applying
a syntax-directed procedure or function. The paper illustrates this for proof
search and inhabitation problems in the simply-typed lambda-calculus, reviewing
results detailed elsewhere, and including new results that obtain extensive
generalizations of the so-called monatomic theorem.


title: Affine flag varieties and quantum symmetric pairs

abstract:
  The quantum groups of finite and affine type $A$ admit geometric realizations
in terms of partial flag varieties of finite and affine type $A$. Recently, the
quantum group associated to partial flag varieties of finite type $B/C$ is
shown to be a coideal subalgebra of the quantum group of finite type $A$. In
this paper we study the structures of Schur algebras and Lusztig algebras
associated to (four variants of) partial flag varieties of affine type $C$. We
show that the quantum groups arising from Lusztig algebras and Schur algebras
via stabilization procedures are (idempotented) coideal subalgebras of quantum
groups of affine $\mathfrak{sl}$ and $\mathfrak{gl}$ types, respectively. In
this way, we provide geometric realizations of eight quantum symmetric pairs of
affine types. We construct monomial and canonical bases of all these quantum
(Schur, Lusztig, and coideal) algebras. For the idempotented coideal algebras
of affine $\mathfrak{sl}$ type, we establish the positivity properties of the
canonical basis with respect to multiplication, comultiplication and a bilinear
pairing. In particular, we obtain a new and geometric construction of the
idempotented quantum affine $\mathfrak{gl}$ and its canonical basis.


title:
Measurement of dijet azimuthal decorrelation in pp collisions at sqrt(s)
  = 8 TeV

abstract:
  A measurement of the decorrelation of azimuthal angles between the two jets
with the largest transverse momenta is presented for seven regions of leading
jet transverse momentum up to 2.2 TeV. The analysis is based on the
proton-proton collision data collected with the CMS experiment at a
centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of
19.7 inverse femtobarns. The dijet azimuthal decorrelation is caused by the
radiation of additional jets and probes the dynamics of multijet production.
The results are compared to fixed-order predictions of perturbative quantum
chromodynamics (QCD), and to simulations using Monte Carlo event generators
that include parton showers, hadronization, and multiparton interactions. Event
generators with only two outgoing high transverse momentum partons fail to
describe the measurement, even when supplemented with next-to-leading-order QCD
corrections and parton showers. Much better agreement is achieved when at least
three outgoing partons are complemented through either next-to-leading-order
predictions or parton showers. This observation emphasizes the need to improve
predictions for multijet production.


title:
Structure-preserving mesh coupling based on the Buffa-Christiansen
  complex

abstract:
  The state of the art for mesh coupling at nonconforming interfaces is
presented and reviewed. Mesh coupling is frequently applied to the modeling and
simulation of motion in electromagnetic actuators and machines. The paper
exploits Whitney elements to present the main ideas. Both interpolation- and
projection-based methods are considered. In addition to accuracy and
efficiency, we emphasize the question whether the schemes preserve the
structure of the de Rham complex, which underlies Maxwell's equations. As a new
contribution, a structure-preserving projection method is presented, in which
Lagrange multiplier spaces are chosen from the Buffa-Christiansen complex. Its
performance is compared with a straightforward interpolation based on Whitney
and de Rham maps, and with Galerkin projection.


title:
Improvement of the Cascadic Multigrid Algorithm with a Gauss Seidel
  Smoother to Efficiently Compute the Fiedler Vector of a Graph Laplacian

abstract:
  In this paper, we detail the improvement of the Cascadic Multigrid algorithm
with the addition of the Gauss Seidel algorithm in order to compute the Fiedler
vector of a graph Laplacian, which is the eigenvector corresponding to the
second smallest eigenvalue. This vector has been found to have applications in
graph partitioning, particularly in the spectral clustering algorithm. The
algorithm is algebraic and employs heavy edge coarsening, which was developed
for the first cascadic multigrid algorithm. We present numerical tests that
test the algorithm against a variety of matrices of different size and
properties. We then test the algorithm on a range of square matrices with
uniform properties in order to prove the linear complexity of the algorithm.


title: Large-Sample Theory for the Bergsma-Dassios Sign Covariance

abstract:
  The Bergsma-Dassios sign covariance is a recently proposed extension of
Kendall's tau. In contrast to tau or also Spearman's rho, the new sign
covariance $\tau^*$ vanishes if and only if the two considered random variables
are independent. Specifically, this result has been shown for continuous as
well as discrete variables. We develop large-sample distribution theory for the
empirical version of $\tau^*$. In particular, we use theory for degenerate
U-statistics to derive asymptotic null distributions under independence and
demonstrate in simulations that the limiting distributions give useful
approximations.


title: Theorems A and B for dagger quasi-Stein spaces

abstract:
  In this article we use the homological methods of the theory of quasi-abelian
categories and some results from functional analysis to prove Theorems A and B
for (a broad sub-class of) dagger quasi-Stein spaces. In particular we show how
to deduce these theorems from the vanishing, under certain hypothesis, of the
higher derived functors of the projective limit functor. Our strategy of the
proof generalizes and puts in a more formal framework the Kiehl's proof for
rigid quasi-Stein spaces.


title: Commissioning of ALFABURST: initial tests and results

abstract:
  Fast Radio Bursts (FRBs) are apparently one-time, relatively bright radio
pulses that have been observed in recent years. The origin of FRBs is currently
unknown and many instruments are being built to detect more of these bursts to
better characterize their physical properties and identify the source
population. ALFABURST is one such instrument. ALFABURST takes advantage of the
7-beam Arecibo L-band Feed Array (ALFA) receiver on the 305-m Arecibo Radio
Telescope in Puerto Rico, to detect FRBs in real-time at L-band (1.4 GHz). We
present the results of recent on-sky tests and observations undertaken during
the commissioning phase of the instrument. ALFABURST is now available for
commensal observations with other ALFA projects.


title: A Machian definition of particle mass in higher-dimensional gravity

abstract:
  A new method involving the effective wave function is used to define the mass
of a particle in a standard five-dimensional extension of general relativity.
The mass is inversely proportional to the magnitude of the scalar field of the
extra dimension. Since the scalar field is global and depends on the
coordinates, this definition for the particle mass agrees with Machs Principle.


title: Constrained Multi-Slot Optimization for Ranking Recommendations

abstract:
  Ranking items to be recommended to users is one of the main problems in large
scale social media applications. This problem can be set up as a
multi-objective optimization problem to allow for trading off multiple,
potentially conflicting objectives (that are driven by those items) against
each other. Most previous approaches to this problem optimize for a single slot
without considering the interaction effect of these items on one another.
  In this paper, we develop a constrained multi-slot optimization formulation,
which allows for modeling interactions among the items on the different slots.
We characterize the solution in terms of problem parameters and identify
conditions under which an efficient solution is possible. The problem
formulation results in a quadratically constrained quadratic program (QCQP). We
provide an algorithm that gives us an efficient solution by relaxing the
constraints of the QCQP minimally. Through simulated experiments, we show the
benefits of modeling interactions in a multi-slot ranking context, and the
speed and accuracy of our QCQP approximate solver against other state of the
art methods.


title: Matrix product and sum rule for Macdonald polynomials

abstract:
  We present a new, explicit sum formula for symmetric Macdonald polynomials
$P_\lambda$ and show that they can be written as a trace over a product of
(infinite dimensional) matrices. These matrices satisfy the
Zamolodchikov--Faddeev (ZF) algebra. We construct solutions of the ZF algebra
from a rank-reduced version of the Yang--Baxter algebra. As a corollary, we
find that the normalization of the stationary measure of the multi-species
asymmetric exclusion process is a Macdonald polynomial with all variables set
equal to one.


title:
Semantic Scan: Detecting Subtle, Spatially Localized Events in Text
  Streams

abstract:
  Early detection and precise characterization of emerging topics in text
streams can be highly useful in applications such as timely and targeted public
health interventions and discovering evolving regional business trends. Many
methods have been proposed for detecting emerging events in text streams using
topic modeling. However, these methods have numerous shortcomings that make
them unsuitable for rapid detection of locally emerging events on massive text
streams. In this paper, we describe Semantic Scan (SS) that has been developed
specifically to overcome these shortcomings in detecting new spatially compact
events in text streams.
  Semantic Scan integrates novel contrastive topic modeling with online
document assignment and principled likelihood ratio-based spatial scanning to
identify emerging events with unexpected patterns of keywords hidden in text
streams. This enables more timely and accurate detection and characterization
of anomalous, spatially localized emerging events. Semantic Scan does not
require manual intervention or labeled training data, and is robust to noise in
real-world text data since it identifies anomalous text patterns that occur in
a cluster of new documents rather than an anomaly in a single new document.
  We compare Semantic Scan to alternative state-of-the-art methods such as
Topics over Time, Online LDA, and Labeled LDA on two real-world tasks: (i) a
disease surveillance task monitoring free-text Emergency Department chief
complaints in Allegheny County, and (ii) an emerging business trend detection
task based on Yelp reviews. On both tasks, we find that Semantic Scan provides
significantly better event detection and characterization accuracy than
competing approaches, while providing up to an order of magnitude speedup.


title: Ultrabright single-photon source on diamond with electrical pumping

abstract:
  The recently demonstrated electroluminescence of color centers in diamond
makes them one of the best candidates for room temperature single-photon
sources. However, the reported emission rates are far off what can be achieved
by state-of-the-art electrically driven epitaxial quantum dots. Since the
electroluminescence mechanism has not yet been elucidated, it is not clear to
what extent the emission rate can be increased. Here we develop a theoretical
framework to study single-photon emission from color centers in diamond under
electrical pumping. The proposed model comprises electron and hole trapping and
releasing, transitions between the ground and excited states of the color
center as well as structural transformations of the center due to carrier
trapping. It provides the possibility to predict both the photon emission rate
and the wavelength of emitted photons. Self-consistent numerical simulations of
the single-photon emitting diode based on the proposed model show that the
photon emission rate can be as high as 100 kcounts s$^{-1}$ at standard
conditions. In contrast to most optoelectronic devices, the emission rate
steadily increases with the device temperature achieving of more than 100
Mcount s$^{-1}$ at 500 K, which is highly advantageous for practical
applications. These results demonstrate the potential of color centers in
diamond as electrically driven non-classical light emitters and provide a
foundation for the design and development of single-photon sources for optical
quantum computation and quantum communication networks operating at room and
higher temperatures.


title: Black Hole: The Interior Spacetime

abstract:
  The information loss paradox is often discussed from the perspective of the
observers who stay outside of a black hole. However, the interior spacetime of
a black hole can be rather nontrivial. We discuss the open problems regarding
the volume of a black hole, and whether it plays any role in information
storage. We also emphasize the importance of resolving the black hole
singularity, if one were to resolve the information loss paradox.


title: Optimal Sample Complexity for Stable Matrix Recovery

abstract:
  Tremendous efforts have been made to study the theoretical and algorithmic
aspects of sparse recovery and low-rank matrix recovery. This paper fills a
theoretical gap in matrix recovery: the optimal sample complexity for stable
recovery without constants or log factors. We treat sparsity, low-rankness, and
potentially other parsimonious structures within the same framework: constraint
sets that have small covering numbers or Minkowski dimensions. We consider
three types of random measurement matrices (unstructured, rank-1, and symmetric
rank-1 matrices), following probability distributions that satisfy some mild
conditions. In all these cases, we prove a fundamental result -- the recovery
of matrices with parsimonious structures, using an optimal (or near optimal)
number of measurements, is stable with high probability.


title: Cosmological singularity theorems for $f(R)$ gravity theories

abstract:
  In the present work some generalizations of the Hawking singularity theorems
in the context of $f(R)$ theories are presented. The assumptions are of these
generalized theorems is that the matter fields satisfy the conditions
$\bigg(T_{ij}-\frac{g_{ij}}{2} T\bigg)k^i k^j\geq 0$ for any generic unit time
like field, that the scalaron takes bounded positive values during its
evolution, and that the resulting space time is globally hyperbolic. Then, if
there exist a Cauchy hyper surface $\Sigma$ for which the expansion parameter
$\theta$ of the geodesic congruence emanating orthogonally from $\Sigma$
satisfies some specific conditions, it may be shown that the resulting space
time is geodesically incomplete. Some mathematical results of reference
\cite{fewster} are very important for proving this. The generalized theorems
presented here apply directly some specific models such as the Hu-Sawicki or
Starobinsky ones \cite{especif3}, \cite{capoziello4}. However, for other
scenarios, some extra assumptions should be implemented for the geodesic
incompleteness to take place. However, the negation of the hypothesis of these
results does not necessarily imply that a singularity is absent, but that other
mathematical results should be considered to prove that.


title: Joint Dimensionality Reduction for Two Feature Vectors

abstract:
  Many machine learning problems, especially multi-modal learning problems,
have two sets of distinct features (e.g., image and text features in news story
classification, or neuroimaging data and neurocognitive data in cognitive
science research). This paper addresses the joint dimensionality reduction of
two feature vectors in supervised learning problems. In particular, we assume a
discriminative model where low-dimensional linear embeddings of the two feature
vectors are sufficient statistics for predicting a dependent variable. We show
that a simple algorithm involving singular value decomposition can accurately
estimate the embeddings provided that certain sample complexities are
satisfied, without specifying the nonlinear link function (regressor or
classifier). The main results establish sample complexities under multiple
settings. Sample complexities for different link functions only differ by
constant factors.


title: Linear Separability in Spatial Databases

abstract:
  Given two point sets $R$ and $B$ in the plane, with cardinalities $m$ and
$n$, respectively, and each set stored in a separate R-tree, we present an
algorithm to decide whether $R$ and $B$ are linearly separable. Our algorithm
exploits the structure of the R-trees, loading into the main memory only
relevant data, and runs in $O(m\log m + n\log n)$ time in the worst case. As
experimental results, we implement the proposed algorithm and executed it on
several real and synthetic point sets, showing that the percentage of nodes of
the R-trees that are accessed and the memory usage are low in these cases. We
also present an algorithm to compute the convex hull of $n$ planar points given
in an R-tree, running in $O(n\log n)$ time in the worst case.


title: Energy-Aware Cooperative Computation in Mobile Devices

abstract:
  New data intensive applications, which are continuously emerging in daily
routines of mobile devices, significantly increase the demand for data, and
pose a challenge for current wireless networks due to scarce resources.
Although bandwidth is traditionally considered as the primary scarce resource
in wireless networks, the developments in communication theory shifts the focus
from bandwidth to other scarce resources including processing power and energy.
Especially, in device-to-device networks, where data rates are increasing
rapidly, processing power and energy are becoming the primary bottlenecks of
the network. Thus, it is crucial to develop new networking mechanisms by taking
into account the processing power and energy as bottlenecks. In this paper, we
develop an energy-aware cooperative computation framework for mobile devices.
In this setup, a group of cooperative mobile devices, within proximity of each
other, (i) use their cellular or Wi-Fi (802.11) links as their primary
networking interfaces, and (ii) exploit their device-to-device connections
(e.g., Wi-Fi Direct) to overcome processing power and energy bottlenecks. We
evaluate our energy-aware cooperative computation framework on a testbed
consisting of smartphones and tablets, and we show that it brings significant
performance benefits.


title: High Dispersion Spectroscopy with Ond\v{r}ejov Echelle Spectrograph

abstract:
  Echelle spectrographs with their high resolution plays important role in
determination of characteristics of stellar lines. Wide field of applications
is focused mainly on the measurements of precise radial velocity applied in
exoplanetary research. In my diploma thesis I am concentrated on the
calibration of the Ond\v{r}ejov Echelle Spectrograph at Astronomical Institute
of the Czech Academy of Sciences. My role was to investigate the wide field of
opportunities how to process the data with the best possible results.
Successful reduction was performed by both Image Reduction and Analysis
Facility (IRAF) and for Open source Pipeline for ESPaDOnS Reduction and
Analysis. This thesis includes the comparison of both pipelines.


title:
Balanced Truncation of Linear Time-Invariant Systems over
  Finite-frequency Ranges

abstract:
  This paper discusses model order reduction of LTI systems over limited
frequency intervals within the framework of balanced truncation. Two new
\emph{frequency-dependent balanced truncation} methods were developed, one is
\emph{SF-type frequency-dependent balanced truncation} to copy with the cases
that only a single dominating point of the operating frequency interval is
pre-known, the other is \emph{interval-type frequency-dependent balanced
truncation} to deal with the cases that both of the upper and lower bound of
frequency interval are known \emph{a priori}. SF-type error bound and
interval-type error bound are derived for the first time to estimate the
desired approximation error over pre-specified frequency interval. We show that
the new methods generally lead to good in-band approximation performance, at
the same time, provide accurate error bounds under certain conditions. Examples
are included for illustration.


title: Spontaneous currents in a bosonic ring

abstract:
  Nonequilibrium dynamics of noninteracting bosons in a one-dimensional
ring-shaped lattice is studied by means of the Kinetic Monte Carlo method. The
system is approximated by the classical XY model (the kinetic term is
neglected) and then the simulations are performed for the planar classical
spins. We study the dynamics that follows a finite-time quench to zero
temperature. If the quench is slow enough the system can equilibrate and
finally reaches the ground state with uniform spin alignment. However, we show
that if the quench is faster than the relaxation rate, the system can get
locked in a current-carrying metastable state characterized by a nonzero
winding number. We analyze how the zero-temperature state depends on the quench
rate.


title:
Deuteron-induced nucleon transfer reactions within an ab initio
  framework: First application to p-shell nuclei

abstract:
  Background: Low-energy transfer reactions in which a proton is stripped from
a deuteron projectile and dropped into a target play a crucial role in the
formation of nuclei in both primordial and stellar nucleosynthesis, as well as
in the study of exotic nuclei using radioactive beam facilities and inverse
kinematics. Ab initio approaches have been successfully applied to describe the
$^3$H$(d,n)^4$He and $^3$He$(d,p)^4$He fusion processes.
  Purpose: An ab initio treatment of transfer reactions would also be desirable
for heavier targets. In this work, we extend the ab initio description of
$(d,p)$ reactions to processes with light $p$-shell nuclei. As a first
application, we study the elastic scattering of deuterium on $^7$Li and the
${}^{7}$Li($d$,$p$)${}^{8}$Li transfer reaction based on a two-body
Hamiltonian.
  Methods: We use the no-core shell model to compute the wave functions of the
nuclei involved in the reaction, and describe the dynamics between targets and
projectiles with the help of microscopic-cluster states in the spirit of the
resonating group method.
  Results: The shape of the excitation functions for deuteron impinging on
${}^{7}$Li are qualitatively reproduced up to the deuteron breakup energy. The
interplay between $d$-$^7$Li and $p$-$^8$Li particle-decay channels determines
some features of the ${}^{9}$Be spectrum above the $d$+${}^{7}$Li threshold.
Our prediction for the parity of the 17.298 MeV resonance is at odds with the
experimental assignment
  Conclusions: Deuteron stripping reactions with $p$-shell targets can now be
computed ab initio, but calculations are very demanding. A quantitative
description of the ${}^{7}$Li($d$,$p$)${}^{8}$Li reaction will require further
work to include the effect of three-nucleon forces and additional decay
channels, and improve the convergence rate of our calculations.


title: Depth and the Local Cohomology of FI_G-modules

abstract:
  In this paper we describe a machinery for homological calculations of
representations of FI_G, and use it to develop a local cohomology theory over
any commutative Noetherian ring. As an application, we show that the depth
introduced by the second author coincides with a more classical invariant from
commutative algebra, and obtain upper bounds of a few important invariants of
FI_G-modules in terms of torsion degrees of their local cohomology groups.


title:
Pairing symmetry of heavy fermion superconductivity in the
  two-dimensional Kondo-Heisenberg lattice model

abstract:
  In the two-dimensional Kondo-Heisenberg lattice model away from half-filled,
the local antiferromagnetic exchange coupling can provide the pairing mechanism
of quasiparticles via the Kondo screening effect, leading to the heavy fermion
superconductivity. We find that the pairing symmetry \textit{strongly} depends
on the Fermi surface (FS) structure in the normal metallic state. When
$J_{H}/J_{K}$ is very small, the FS is a small hole-like circle around the
corner of the Brillouin zone, and the s-wave pairing symmetry has a lower
ground state energy. For the intermediate coupling values of $J_{H}/J_{K}$, the
extended s-wave pairing symmetry gives the favored ground state. However, when
$J_{H}/J_{K}$ is larger than a critical value, the FS transforms into four
small hole pockets crossing the boundary of the magnetic Brillouin zone, and
the d-wave pairing symmetry becomes more favorable. In that regime, the
resulting superconducting state is characterized by either nodal d-wave or
nodeless d-wave state, depending on the conduction electron filling factor as
well. A continuous phase transition exists between these two states. This
result may be related to the phase transition of the nodal d-wave state to a
fully gapped state, which is recently observed in Yb doped CeCoIn$_{5}$.


title:
Constraining the Contribution of Galaxies and Active Galactic Nuclei to
  Cosmic Reionization

abstract:
  Understanding the detailed process of cosmic reionization is one of the
remaining problems in astrophysics and cosmology. Here we construct a model of
cosmic reionization that includes contribution from high-$z$ galaxies and
active galactic nuclei (AGNs), and calculate the reionization and thermal
histories with the model. To keep the model to be general and realistic, we
vary the escape fraction of ionizing photons, $f_{\rm esc}$, and the faint-end
slope of the AGN luminosity function at high redshifts, $\alpha_{\rm hz}$,
within the constraints from the observed cosmic star formation history and the
observed bright-end UV luminosity functions at $z \leq 6$. Additionally, we
model the spectral energy distribution (SED) of AGNs which depends on the
Eddington ratio and the black-hole mass. By comparing the computed reionization
histories with the observed \ion{H}{i} fractions and the optical depth for
Thomson scattering from Planck, we find that $\alpha_{\rm hz} > -1.5$ and
$f_{\rm esc} < 0.15$ are favored when we employ the bright-end luminosity
function obtained by Giallongo et al. Our result suggests that an AGN-dominated
model with the abundance of faint-AGNs being as large as the estimate by
Giallongo et al. is allowed only if the contribution from high-z galaxies is
almost negligible, while a galaxy-dominant model is also allowed. We also find
that the shape of SED has a significant impact on the thermal history.
Therefore it is expected that measurements of the thermal state of the IGM
provide useful information on properties of ionizing sources.


title:
Finite-Frequency Model Order Reduction of Linear Systems via
  Parameterized Frequency-dependent Balanced Truncation

abstract:
  Balanced truncation is one of the most common model order reduction schemes.
In this paper, we study finite-frequency model order reduction (FF-MOR)
problems of linear continuous-time systems within the framework of balanced
truncation method. Firstly, we construct a family of parameterized
frequency-dependent (PFD) mappings which generate discrete-time PFD mapped
systems and continuous-time PFD mapped systems of the given continuous-time
system. The relationships between the maximum singular value of the given
system over pre-specified frequency ranges and the maximum singular value of
the PFD mapped systems over entire frequency range are established. By
exploiting the properties of the discrete-time PFD mapped systems, a new
parameterized frequency-dependent balanced truncation (PFDBT) method providing
finite-frequency type error bound with respect to the maximum singular value of
the approximation error systems are developed. Examples are included for
illustration.


title: Convex Optimization For Non-Convex Problems via Column Generation

abstract:
  We apply column generation to approximating complex structured objects via a
set of primitive structured objects under either the cross entropy or L2 loss.
We use L1 regularization to encourage the use of few structured primitive
objects. We attack approximation using convex optimization over an infinite
number of variables each corresponding to a primitive structured object that
are generated on demand by easy inference in the Lagrangian dual. We apply our
approach to producing low rank approximations to large 3-way tensors.


title: Simple Characterizations of Potential Games and Zero-sum Games

abstract:
  We provide several tests to determine whether a game is a potential game or
whether it is a zero-sum equivalent game---a game which is strategically
equivalent to a zero-sum game in the same way that a potential game is
strategically equivalent to a common interest game. We present a unified
framework applicable for both potential and zero-sum equivalent games by
deriving a simple but useful characterization of these games. This allows us to
re-derive known criteria for potential games, as well as obtain several new
criteria. In particular, we prove (1) new integral tests for potential games
and for zero-sum equivalent games, (2) a new derivative test for zero-sum
equivalent games, and (3) a new representation characterization for zero-sum
equivalent games.


title: Stochastic orders and the frog model

abstract:
  The frog model starts with one active particle at the root of a graph and
some number of dormant particles at all nonroot vertices. Active particles
follow independent random paths, waking all inactive particles they encounter.
We prove that certain frog model statistics are monotone in the initial
configuration for two nonstandard stochastic dominance relations: the
increasing concave and the probability generating function orders.
  This extends many canonical theorems. We connect recurrence for random
initial configurations to recurrence for deterministic configurations. Also,
the limiting shape of activated sites on the integer lattice respects both of
these orders. Other implications include monotonicity results on transience of
the frog model where the number of frogs per vertex decays away from the
origin, on survival of the frog model with death, and on the time to visit a
given vertex in any frog model.