title:
An Industrial Case Study on Measuring the Quality of the Requirements
  Scoping Process

abstract:
  Decision making and requirements scoping occupy central roles in helping to
develop products that are demanded by the customers and ensuring company
strategies are accurately realized in product scope. Many companies experience
continuous and frequent scope changes and fluctuations but struggle to measure
the phenomena and correlate the measurement to the quality of the requirements
process. We present the results from an exploratory interview study among 22
participants working with requirements management processes at a large company
that develops embedded systems for a global market. Our respondents shared
their opinions about the current set of requirements management process metrics
as well as what additional metrics they envisioned as useful. We present a set
of metrics that describe the quality of the requirements scoping process. The
findings provide practical insights that can be used as input when introducing
new measurement programs for requirements management and decision making.


title: An FPTAS for Counting Proper Four-Colorings on Cubic Graphs

abstract:
  Graph coloring is arguably the most exhaustively studied problem in the area
of approximate counting. It is conjectured that there is a fully
polynomial-time (randomized) approximation scheme (FPTAS/FPRAS) for counting
the number of proper colorings as long as $q \geq \Delta + 1$, where $q$ is the
number of colors and $\Delta$ is the maximum degree of the graph. The bound of
$q = \Delta + 1$ is the uniqueness threshold for Gibbs measure on
$\Delta$-regular infinite trees. However, the conjecture remained open even for
any fixed $\Delta\geq 3$ (The cases of $\Delta=1, 2$ are trivial). In this
paper, we design an FPTAS for counting the number of proper $4$-colorings on
graphs with maximum degree $3$ and thus confirm the conjecture in the case of
$\Delta=3$. This is the first time to achieve this optimal bound of $q = \Delta
+ 1$. Previously, the best FPRAS requires $q > \frac{11}{6} \Delta$ and the
best deterministic FPTAS requires $q > 2.581\Delta + 1$ for general graphs. In
the case of $\Delta=3$, the best previous result is an FPRAS for counting
proper 5-colorings. We note that there is a barrier to go beyond $q = \Delta +
2$ for single-site Glauber dynamics based FPRAS and we overcome this by
correlation decay approach. Moreover, we develop a number of new techniques for
the correlation decay approach which can find applications in other approximate
counting problems.


title: Volterra type operators on growth Fock spaces

abstract:
  Let $\omega$ be an unbounded radial weight on $\mathbb{C}^d$, $d\ge 1$. Using
results related to approximation of $\omega$ by entire maps, we investigate
Volterra type and weighted composition operators defined on the growth space
$\mathcal{A}^\omega(\mathbb{C}^d)$. Special attention is given to the operators
defined on the growth Fock spaces.


title:
Integral representations of equally positive integer-indexed harmonic
  sums at infinity

abstract:
  We identify a partition-theoretic generalization of Riemann zeta function and
the equally positive integer-indexed harmonic sums at infinity, to obtain the
generating function and the integral representations of the latter. The special
cases coincide with zeta values at positive integer arguments.


title:
Upper bound on the number of ramified primes for odd order solvable
  groups

abstract:
  Let $G$ be a finite group and let $ram^{t}(G)$ denote the minimal positive
integer $n$ such that $G$ can be realized as the Galois group of a tamely
ramified extension of $\mathbb{Q}$ ramified only at $n$ finite primes. Let
$d(G)$ denote the minimal non negative integer for which there exists a subset
$X$ of $G$ with $d(G)$ elements such that the normal subgroup of $G$ generated
by $X$ is all of $G$. It is known that $d(G)\leq ram^{t}(G)$. However, it is
unknown whether or not every finite group $G$ can be realized as a Galois group
of a tamely ramified extension of $\mathbb{Q}$ with exactly $d(G)$ ramified
primes. We will show that $3\cdot log(|G|)$ is an upper bound for $ram^{t}(G)$
for all odd order solvable group $G$.


title: On p-Robust Saturation for hp-AFEM

abstract:
  We consider the standard adaptive finite element loop SOLVE, ESTIMATE, MARK,
REFINE, with ESTIMATE being implemented using the $p$-robust equilibrated flux
estimator, and MARK being D\"orfler marking. As a refinement strategy we employ
$p$-refinement. We investigate the question by which amount the local
polynomial degree on any marked patch has to be increase in order to achieve a
$p$-independent error reduction. The resulting adaptive method can be turned
into an instance optimal $hp$-adaptive method by the addition of a coarsening
routine.


title:
Nonlinear dynamics of a functionally graded piezoelectric
  micro-resonator in the vicinity of the primary resonance

abstract:
  This research is on the nonlinear dynamics of a two-sided electrostatically
actuated capacitive micro-beam. The microresonator is composed of silicon and
PZT as a piezoelectric material. PZT is functionally distributed along the
height of the micro-beam according to the power law distribution. The
micro-resonator is simultaneously subjected to DC piezoelectric and two-sided
electrostatic actuations. The DC piezoelectric actuation leads to the
generation of an axial force along the length of the micro-beam and this is
used as a tuning tool to shift the primary resonance of the micro-resonator.
The governing equation of the motion is derived by the minimization of the
Hamiltonian and generalized to the viscously damped systems. The periodic
solutions in the vicinity of the primary resonance are detected by means of the
shooting method and their stability is investigated by determining the
so-called Floquet exponents of the perturbed motions. The basins of attraction
corresponding to three individual periodic orbits are determined. The results
depict that the higher the amplitude of the periodic orbit, the smaller is the
area of the attractor


title: Relativistic constituent model in sector of light mesons

abstract:
  We present a brief survey of some results on electroweak properties of
composite systems that are obtained in the frameworks of our version of the
instant form of relativistic quantum mechanics (RQM). Our approach describes
well the $\pi$- and the $\rho$- mesons in wide range of momentum transfers
$Q^{2}$. At large $Q^{2}$ the obtained pion form factor asymptotics coincides
with that of QCD predictions. The method permits to perform analytic
continuation of pion form factor to complex plane of momentum transfers that is
in accordance with predictions of quantum field theory.


title: Passage through a potential barrier and multiple wells

abstract:
  Consider the semiclassical limit, as the Planck constant $\hbar\ri 0$, of
bound states of a one-dimensional quantum particle in multiple potential wells
separated by barriers. We show that, for each eigenvalue of the Schr\"odinger
operator, the Bohr-Sommerfeld quantization condition is satisfied at least for
one potential well. The proof of this result relies on a study of real wave
functions in a neighborhood of a potential barrier. We show that, at least from
one side, the barrier fixes the phase of wave functions in the same way as a
potential barrier of infinite width. On the other hand, it turns out that for
each well there exists an eigenvalue in a small neighborhood of every point
satisfying the Bohr-Sommerfeld condition.


title: Effect of gamma-strength on nuclear reaction calculations

abstract:
  The results of the study of gamma-transition description in fast neutron
capture and photofission are presented. Recent experimental data were used,
namely, the spectrum of prompt gamma-rays in the energy range 2{\div}18 MeV
from 14-MeV neutron capture in natural Ni and isomeric ratios in primary
fragments of photofission of the isotopes of U, Np and Pu by bremsstrahlung
with end-point energies $E_e$= 10.5, 12 and 18 MeV. The data are compared with
the theoretical calculations performed within EMPIRE 3.2 and TALYS 1.6 codes.
The mean value of angular momenta and their distributions were determined in
the primary fragments $^{84}$Br, $^{97}$Nb, $^{90}$Rb, $^{131,133}$Te,
$^{132}$Sb, $^{132,134}$I, $^{135}$Xe of photofissions. An impact of the
characteristics of nuclear excited states on the calculation results is studied
using different models for photon strength function and nuclear level density.


title: The Entropy Region is not Closed Under Duality

abstract:
  We import a duality notion coming from polymatroids to define duality for
information inequalities. We show that the entropy region for $n\ge 5$ is not
closed under duality. Our result answers an open question of Mat\`u\v{s}
(1992).


title: Investigation of open clusters based on IPHAS and APASS survey data

abstract:
  We adapt the classical Q-method based on a reddening-free parameter
constructed from three passband magnitudes to thwe filter set of IPHAS survey
and combine it with the maximum-likelihood-based cluster parameter estimator by
Naylor and Jeffries (2006) to determine the extinction, heliocentric distances,
and ages of young open clusters using Halpha and ri data. Themethod is also
adapted for the case of signific ant variations of extinction across the
cluster rfield. Our technique is validated by comparing the colour excesses,
disdtances, and ages determined in this study with the most bona fide values
reported for the 18 well-studied young open clusters in the past, and a fairly
good agreement is found between our extinction and distance estimnates and
earlier published results. although our age estimates are not very consistent
with those published by other authors. We also show that individual extinction
values can be determined rather accurately for stars with (r-i)0>0.1. Our
results open up a prospect fpr determining a uniform set of parameters for
northern clusters based on homogeneous photometric data, and for searching for
new, hitherto undiscovered open clusters.


title:
Null Controllability of the Kuramoto-Sivashinsky Equation on star-shaped
  trees

abstract:
  In this paper we treat controllability properties for the linear
Kuramoto-Sivashinsky equation on a network with two types of boundary
conditions. More precisely, the equation is considered on a star-shaped tree
with Dirichlet and Neumann boundary conditions. By using the moment theory we
can derive null-controllability properties with boundary controls acting on the
external vertices of the tree. In particular, the controllability holds if the
anti-diffusion parameter of the involved equation does not belong to a critical
countable set of real numbers. We point out that the critical set for which the
null-controllability fails differs from the first model to the second one.


title:
Analysis of coherent quantum cryptography protocol vulnerability to an
  active beam-splitting attack

abstract:
  We consider a new type of attack on a coherent quantum key distribution
protocol [coherent one-way (COW) protocol]. The main idea of the attack
consists in measuring individually the intercepted states and sending the rest
of them unchanged. We have calculated the optimum values of the attack
parameters for an arbitrary length of a channel length and compared this novel
attack with a standard beam-splitting attack.


title: A splitting method for the augmented Burgers equation

abstract:
  In this paper we consider a splitting method for the augmented Burgers
equation and prove that it is of first order. We also analyze the large-time
behavior of the approximated solution by obtaining the first term in the
asymptotic expansion. We prove that, when time increases, these solutions
behave as the self-similar solutions of the viscous Burgers equation


title: L-homology on ball complexes and products

abstract:
  We construct homology theories with coefficients in L-spectra on the category
of ball complexes and we define products in this setting. We also obtain
signatures of geometric situations in these homology groups and prove product
formulae which we hope will clarify products used in the theory of the total
surgery obstruction.


title: Greatest common divisors of iterates of polynomials

abstract:
  Following work of Bugeaud, Corvaja, and Zannier for integers, Ailon and
Rudnick prove that for any multiplicatively independent polynomials, $a, b \in
{\mathbb C}[x]$, there is a polynomial $h$ such that for all $n$, we have
  \[ \gcd(a^n - 1, b^n - 1) \mid h\] We prove a compositional analog of this
theorem, namely that if $f, g \in {\mathbb C}[x]$ are nonconstant
compositionally independent polynomials and $c(x) \in {\mathbb C}[x]$, then
there are at most finitely many $\lambda$ with the property that there is an
$n$ such that $(x - \lambda)$ divides $\gcd(f^{\circ n}(x) - c(x), g^{\circ
n}(x) - c(x))$.


title: Recovery of dynamic interference

abstract:
  We develop general quantitative criteria for dynamic interference, a
manifestation of double-slit interference in time which should be realizable
with brilliant state-of-the-art high-frequency laser sources. Our analysis
reveals that the observation of dynamic interference hinges upon maximizing the
difference between the dynamic polarization of the initial bound and the final
continuum state of the electron during the light pulse, while keeping depletion
of the initial state small. Confirmed by numerical results, we predict that
this is impossible for the hydrogen ground-state but feasible with excited
states explicitly exemplified with the hydrogen 2p-state.


title: LHC data and cosmic ray coplanarity at superhigh energies

abstract:
  A new phenomenological model FANSY 2.0 is designed, which makes it possible
to simulate hadron interactions via traditional QGSM-type particle generation
as well as coplanar generation of most energetic particles, observed in cosmic
ray experiments. FANSY 2.0 reproduces a lot of LHC (ALICE, ATLAS, CMS, TOTEM,
LHCf) data. Results of model simulations are compared with LHC data. Problems
of coplanarity are considered and a testing experiment is proposed.


title:
Kaon semileptonic decays with $N_f=2+1+1$ HISQ fermions and physical
  light-quark masses

abstract:
  We discuss the reduction of errors in the calculation of the form factor
$f_+^{K \pi}(0)$ with HISQ fermions on the $N_f=2+1+1$ MILC configurations from
increased statistics on some key ensembles, new data on ensembles with lattice
spacings down to 0.042 fm and the study of finite-volume effects within
staggered ChPT. We also study the implications for the unitarity of the CKM
matrix in the first row and for current tensions with leptonic determinations
of $\vert V_{us}\vert$.


title:
Small compressive strain induced semiconductor-metal transition and
  tensile strain enhanced thermoelectric properties in monolayer
  $\mathrm{PtTe_2}$

abstract:
  Biaxial strain effects on electronic structures and thermoelectric properties
of monolayer $\mathrm{PtTe_2}$ are investigated by using generalized gradient
approximation (GGA) plus spin-orbit coupling (SOC) for the electron part and
GGA for the phonon part. Calculated results show that small compressive strain
(about -3\%) can induce semiconductor-to-metal transition, which can easily be
achieved in experiment. The conduction bands convergence is observed for
unstrained $\mathrm{PtTe_2}$, which can be removed by both compressive and
tensile strains. Tensile strain can give rise to valence bands convergence by
changing the position of valence band maximum (VBM), which can induce enhanced
Seebeck coefficient, being favorable for high power factor. It is found that
tensile strain can also reduce lattice thermal conductivity, which at the
strain of 4\% can decrease by about 19\% compared to unstrained one at room
temperature. By considering tensile strain effects on $ZT_e$ and lattice
thermal conductivity, tensile strain indeed can improve p-type efficiency of
thermoelectric conversion. Our results demonstrate the potential of strain
engineering in $\mathrm{PtTe_2}$ for applications in electronics and
thermoelectricity.


title: WINDOW: Wideband Demodulator for Optical Waveforms

abstract:
  Optical communication systems, which operate at very high rates, are often
limited by the sampling rate bottleneck. The optical wideband regime may exceed
analog to digital converters (ADCs) front-end bandwidth. Multi-channel sampling
approaches, such as multicoset or interleaved ADCs, have been proposed to
sample the wideband signal using several channels. Each channel samples below
the Nyquist rate such that the overall sampling rate is preserved. However,
this scheme suffers from two practical limitations that make its implementation
difficult. First, the inherent anti-aliasing filter of the samplers distorts
the wideband signal. Second, it requires accurate time shifts on the order of
the signal's Nyquist rate, which are challenging to maintain. In this work, we
propose an alternative multi-channel sampling scheme, the wideband demodulator
for optical waveforms (WINDOW), based on analog RF demodulation, where each
channel aliases the spectrum using a periodic mixing function before
integration and sampling. We show that intentionally using the inherent ADC
filter to perform integration increases the signal to noise ratio (SNR). We
demonstrate both theoretically and through numerical experiments that our
system outperforms multicoset in terms of signal recovery and symbol estimation
in the presence of both thermal and quantization noise but is slightly less
robust to timing jitter.


title:
The phase transition in hot $\Lambda$ hypernuclei within relativistic
  Thomas-Fermi approximation

abstract:
  A self-consistent description for hot $\Lambda$ hypernuclei in hypothetical
big boxes is developed within the relativistic Thomas-Fermi approximation in
order to investigate directly the liquid-gas phase coexistence in strangeness
finite nuclear systems. We use the relativistic mean-field model for nuclear
interactions. The temperature dependence of $\Lambda$ hyperon density,
$\Lambda$ hyperon radius, excitation energies, specific heat, and the binding
energies of $\Lambda$ hypernuclei from $^{16}_{\Lambda}$O to
$^{208}_{\Lambda}$Pb in phase transition region are calculated by using the
subtraction procedure in order to separate the hypernucleus from the
surrounding baryon gas. The $\Lambda$ central density is very sensitive to the
temperature. The radii of $\Lambda$ hyperon at high temperature become very
large. In the relativistic Thomas-Fermi approximation with the subtraction
procedure, the properties of hypernuclei are independent of the size of the box
in which the calculation is performed. The level density parameters of
hypernuclei in the present work are confirmed to be almost constant at low
temperature. It is also found that the single-$\Lambda$ binding energies of
$\Lambda$ hypernuclei are largely reduced with increasing temperature.


title:
Cross-lingual Dataless Classification for Languages with Small Wikipedia
  Presence

abstract:
  This paper presents an approach to classify documents in any language into an
English topical label space, without any text categorization training data. The
approach, Cross-Lingual Dataless Document Classification (CLDDC) relies on
mapping the English labels or short category description into a Wikipedia-based
semantic representation, and on the use of the target language Wikipedia.
Consequently, performance could suffer when Wikipedia in the target language is
small. In this paper, we focus on languages with small Wikipedias,
(Small-Wikipedia languages, SWLs). We use a word-level dictionary to convert
documents in a SWL to a large-Wikipedia language (LWLs), and then perform CLDDC
based on the LWL's Wikipedia. This approach can be applied to thousands of
languages, which can be contrasted with machine translation, which is a
supervision heavy approach and can be done for about 100 languages. We also
develop a ranking algorithm that makes use of language similarity metrics to
automatically select a good LWL, and show that this significantly improves
classification of SWLs' documents, performing comparably to the best bridge
possible.


title:
Extended and localized Hopf-Turing mixed-mode in non-instantaneous Kerr
  cavities

abstract:
  We investigate the spatio-temporal dynamics of a ring cavity filled with a
non-instantaneous Kerr medium and driven by a coherent injected beam. We show
the existence of a stable mixed-mode solution that can be either extended or
localized in space. The mixed-mode solutions are obtained in a regime where
Turing instability (often called modulational instability) interacts with
self-pulsing phenomenon (Andronov-Hopf bifurcation). We numerically describe
the transition from stationary inhomogeneous solutions to a branch of
mixed-mode solutions. We characterize this transition by constructing the
bifurcation diagram associated with these solutions. Finally, we show stable
localized mixed-mode solutions, which consist of time-periodic oscillations
that are localized in space.


title: Extended soft-wall model for the QCD phase diagram

abstract:
  The soft-wall model, emerging as bottom-up holographic scenario anchored in
the AdS/CFT correspondence, displays the disappearance of normalisable modes
referring to vector mesons at a temperature $T_{\dis}$ depending on the
chemical potential $\mu$, $T_{\dis}(\mu)$. We explore options for making
$T_{\dis}(\mu)$ consistent with the freeze-out curve $T_{\rm f.o.}(\mu)$ from
relativistic heavy-ion collisions and the cross-over curve $T_{\rm c}(\mu)$
from QCD at small values of $\mu$.


title:
Joint Representation Learning of Text and Knowledge for Knowledge Graph
  Completion

abstract:
  Joint representation learning of text and knowledge within a unified semantic
space enables us to perform knowledge graph completion more accurately. In this
work, we propose a novel framework to embed words, entities and relations into
the same continuous vector space. In this model, both entity and relation
embeddings are learned by taking knowledge graph and plain text into
consideration. In experiments, we evaluate the joint learning model on three
tasks including entity prediction, relation prediction and relation
classification from text. The experiment results show that our model can
significantly and consistently improve the performance on the three tasks as
compared with other baselines.


title:
Geometrical description of the phase transition in the Ga\'zdzicki
  Gorenstein model

abstract:
  The derivation of the phase transition in the model of Ga\'zdzicki and
Gorenstein is generalized and simplified by using a geometrical construction.


title: Transversality for the moduli space of Spin(7)-instantons

abstract:
  We construct the moduli space of Spin(7)-instantons on a hermitian complex
vector bundle over a closed 8-dimensional manifold endowed with a (possibly
non-integrable) Spin(7)-structure. We find suitable perturbations that achieve
regularity of the moduli space, so that it is smooth and of the expected
dimension over the irreducible locus.


title: Meson masses and decay constants at large $N$

abstract:
  Meson masses and decay constants in the large $N$ limit of SU($N$) gauge
theory are determined using the twisted Eguchi-Kawai reduced model. To this
end, we make use of a recently defined smearing method valid on the one-point
lattice. This procedure, in combination with a variational analysis, allows to
obtain reliable values for these quantities.


title:
Spatial correlations in bed load transport: evidence, importance, and
  modelling

abstract:
  This article examines the spatial {dynamics of bed load particles} in water.
We focus particularly on the fluctuations of particle activity, which is
defined as the number of moving particles per unit bed {length}. Based on a
stochastic model recently proposed by \citet{Ancey2013}, we derive the second
moment of particle activity analytically; that is the spatial correlation
functions of particle activity. From these expressions, we show that large
moving particle clusters can develop spatially. Also, we provide evidence that
fluctuations of particle activity are scale-dependent. Two characteristic
lengths emerge from the model: a saturation length $\ell_{sat}$ describing the
length needed for a perturbation in particle activity to relax to the
homogeneous solution, and a correlation length $\ell_c$ describing the typical
size of moving particle clusters. A dimensionless P\'eclet number can also be
defined according to the transport model. Three different experimental data
sets are used to test the theoretical results. We show that the stochastic
model describes spatial patterns of particle activity well at all scales. In
particular, we show that $\ell_c$ and $\ell_{sat}$ may be relatively large
compared to typical scales encountered in bed load experiments (grain diameter,
water depth, bed form wavelength, flume length...) suggesting that the spatial
fluctuations of particle activity have a non-negligible impact on the average
transport process.


title: Noncommutative Borsuk-Ulam-type conjectures revisited

abstract:
  Let $H$ be the C*-algebra of a non-trivial compact quantum group acting
freely on a unital C*-algebra $A$. It was recently conjectured that there does
not exist an equivariant $*$-homomorphism from $A$ (type-I case) or $H$
(type-II case) to the equivariant noncommutative join C*-algebra
$A\circledast^\delta H$. When $A$ is the C*-algebra of functions on a sphere,
and $H$ is the C*-algebra of functions on ${\mathbb Z}/2{\mathbb Z}$ acting
antipodally on the sphere, then the conjecture of type I becomes the celebrated
Borsuk-Ulam theorem. Following recent work of Passer, we prove the conjecture
of type I for compact quantum groups admitting a non-trivial torsion character.
Next, we prove that, if a compact quantum group admits a representation whose
\mbox{$K_1$-class} is non-trivial and $A$ admits a character, then a stronger
version of the type-II conjecture holds: the finitely generated projective
module associated with $A\circledast^\delta H$ via this representation is not
stably free. In particular, we apply this result to the $q$-deformations of
compact connected semisimple Lie groups and to the reduced group C*-algebras of
free groups on $n>1$ generators.


title: On the two symmetries in the theory of m-Hessian operators

abstract:
  We show that the modern theory of fully nonlinear operators had been started
by the skew symmetry of minors in cooperation with the symmetry of symmetric
functions. The paper presents some consequences of this interaction for the
m-Hessian operators. One of them is a setting of the isoperimetric variational
problem for Hessian integral. The m-admissible minimizer is found, what brings
out a new simple proof of the well known Poincare - type inequalities for
Hessian integrals. Also a new set of inequalities, generated by a special
finite set of functions, is found.


title: Weighted floating bodies and polytopal approximation

abstract:
  Asymptotic results for weighted floating bodies are established and used to
obtain new proofs for the existence of floating areas on the sphere and in
hyperbolic space and to establish the existence of floating areas in Hilbert
geometries. Results on weighted best and random approximation and the new
approach to floating areas are combined to derive new asymptotic approximation
results on the sphere, in hyperbolic space and in Hilbert geometries.


title: Generalized Attracting Horseshoes and Chaotic Strange Attractors

abstract:
  A generalized attracting horseshoe is introduced as a new paradigm for
describing chaotic strange attractors (of arbitrary finite rank) for smooth and
piecewise smooth maps f from Q to Q, where Q is a homeomorph of the unit
interval in real m-space for any integer m > 1. The main theorems for
generalized attracting horseshoes are shown to apply to Henon and Lozi maps,
thereby leading to rather simple new chaotic strange attractor existence proofs
that apply to a range of parameter values that includes those of earlier
proofs.


title:
Statistics of bedload transport over steep slopes: Separation of time
  scales and collective motion

abstract:
  Steep slope streams show large fluctuations of sediment discharge across
several time scales. These fluctuations may be inherent to the internal
dynamics of the sediment transport process. A probabilistic framework thus
seems appropriate to analyze such a process. In this letter, we present an
experimental study of bedload transport over a steep slope flume for small to
moderate Shields numbers. The sampling technique allows the acquisition of
high-resolution time series of the solid discharge. The resolved time scales
range from $10^{-2}$s up to $10^{5}$s. We show that two distinct time scales
can be observed in the probability density function for the waiting time
between moving particles. We make the point that the separation of time scales
is related to collective dynamics. Proper statistics of a Markov process
including collective entrainment are derived. The separation of time scales is
recovered theoretically for low entrainment rates.


title:
Responses to Critiques on Machine Learning of Criminality Perceptions
  (Addendum of arXiv:1611.04135)

abstract:
  In November 2016 we submitted to arXiv our paper "Automated Inference on
Criminality Using Face Images". It generated a great deal of discussions in the
Internet and some media outlets. Our work is only intended for pure academic
discussions; how it has become a media consumption is a total surprise to us.
Although in agreement with our critics on the need and importance of policing
AI research for the general good of the society, we are deeply baffled by the
ways some of them mispresented our work, in particular the motive and objective
of our research.


title:
Relation-theoretic metrical fixed point theorems under nonlinear
  contractions

abstract:
  We establish fixed point theorems for nonlinear contractions on a metric
space (not essentially complete) endowed with an arbitrary binary relation. Our
results extend, generalize, modify and unify several known results especially
those contained in Samet and Turinici [Commun. Math. Anal. 13, 82-97 (2012)]
and Alam and Imdad [J. Fixed Point Theory Appl. 17(4), 693-702 (2015)].
Interestingly a corollary to one of our main results proved under symmetric
closure of any binary relation remains a sharpened version of a theorem due to
Samet and Turinici. Finally, we use examples to highlight the realized
improvements in the results proved in this paper.


title: Gorenstein modifications and $\mathbb{Q}$-Gorenstein rings

abstract:
  Let $R$ be a Cohen--Macaulay normal domain with a canonical module
$\omega_R$. It is proved that if $R$ admits a noncommutative crepant resolution
(NCCR), then necessarily it is $\mathbb{Q}$-Gorenstein. Writing $S$ for a
Zariski local canonical cover of $R$, then a tight relationship between the
existence of noncommutative (crepant) resolutions on $R$ and $S$ is given. A
weaker notion of Gorenstein modification is developed, and a similar tight
relationship is given. There are three applications: non-Gorenstein quotient
singularities by connected reductive groups cannot admit an NCCR, the centre of
any NCCR is log-terminal, and the Auslander--Esnault classification of
two-dimensional CM-finite algebras can be deduced from
Buchweitz--Greuel--Schreyer.


title:
Hand Gesture Recognition for Contactless Device Control in Operating
  Rooms

abstract:
  Hand gesture is one of the most important means of touchless communication
between human and machines. There is a great interest for commanding electronic
equipment in surgery rooms by hand gesture for reducing the time of surgery and
the potential for infection. There are challenges in implementation of a hand
gesture recognition system. It has to fulfill requirements such as high
accuracy and fast response. In this paper we introduce a system of hand gesture
recognition based on a deep learning approach. Deep learning is known as an
accurate detection model, but its high complexity prevents it from being
fabricated as an embedded system. To cope with this problem, we applied some
changes in the structure of our work to achieve low complexity. As a result,
the proposed method could be implemented on a naive embedded system. Our
experiments show that the proposed system results in higher accuracy while
having less complexity in comparison with the existing comparable methods.


title: Wobbling motion in $^{135}$Pr within a collective Hamiltonian

abstract:
  The recently reported wobbling bands in $^{135}$Pr are investigated by the
collective Hamiltonian, in which the collective parameters, including the
collective potential and the mass parameter, are respectively determined from
the tilted axis cranking (TAC) model and the harmonic frozen alignment (HFA)
formula. It is shown that the experimental energy spectra of both yrast and
wobbling bands are well reproduced by the collective Hamiltonian. It is
confirmed that the wobbling mode in $^{135}$Pr changes from transverse to
longitudinal with the rotational frequency. The mechanism of this transition is
revealed by analyzing the effective moments of inertia of the three principal
axes, and the corresponding variation trend of the wobbling frequency is
determined by the softness and shapes of the collective potential.


title:
Mixed LQG and $H_\infty$ Coherent Feedback Control for Linear Quantum
  Systems

abstract:
  The purpose of this paper is to study the mixed linear quadratic Gaussian
(LQG) and $H_\infty$ optimal control problem for linear quantum stochastic
systems, where the controller itself is also a quantum system, often referred
to as "coherent feedback controller". A lower bound of the LQG control is
proved. Then two different methods, rank constrained linear matrix inequality
(LMI) method and genetic algorithm are proposed for controller design. A
passive system (cavity) and a non-passive one (degenerate parametric amplifier,
DPA) demonstrate the effectiveness of these two proposed algorithms.


title: A Note on Approximate Inverse Iteration

abstract:
  Different variants of approximate inverse iteration like the locally optimal
block preconditioned conjugate gradient method became in recent years
increasingly popular for the solution of the large matrix eigenvalue problems
arising from the discretization of selfadjoint elliptic partial differential
equations, in particular for the calculation of the minimum eigenvalue. We
extend in this little note the classical convergence theory of D'yakonov and
Orekhov [Math. Notes 27 (1980)] to the case of operators with an essential
spectrum on infinite dimensional Hilbert spaces and allow for arbitrary,
sufficiently small perturbations of the solutions of the equation that links
the iterates. The note complements the much more elaborate convergence theory
of Neymeyr and Knyazev and Neymeyr for the matrix case (see [Knyazev and
Neymeyr, SIAM J. Matrix Anal. Appl. 31 (2009)] and the references therein) and
is suitable for classroom presentation.


title:
A highly pixelated CdZnTe detector based on \textit{Topmetal-${II}^-$}
  sensor

abstract:
  \textit{Topmetal-${II}^-$} is a low noise CMOS pixel direct charge sensor
with a pitch of 83$\mu m$. CdZnTe is an excellent semiconductor material for
radiation detection. The combination of CdZnTe and the sensor makes it possible
to build a detector with high spatial resolution. In our experiments, an epoxy
adhesive is used as the conductive medium to connect the sensor and Cadmium
Zinc Telluride (CdZnTe). The diffusion coefficient and charge efficiency of
electrons are measured at a low bias voltage of -2 Volts, and the image of a
single alpha is clear with a reasonable spatial resolution. The detector of
such structure has the potential to be applied in X-ray imaging systems with a
further improvements of the sensor.


title: Rainich Conditions in (2+1)-Dimensional Gravity

abstract:
  In (3 + 1) spacetime dimensions the Rainich conditions are a set of equations
expressed solely in terms of the metric tensor which are equivalent to the
Einstein-Maxwell equations for non-null electromagnetic fields. Here we provide
the analogous conditions for (2 + 1)-dimensional gravity coupled to
electromagnetism. Both the non-null and null cases are treated. The
construction of these conditions is based upon reducing the problem to that of
gravity coupled to a scalar field, which we have treated elsewhere. These
conditions can be easily extended to other theories of (2 + 1)-dimensional
gravity. For example, we apply the geometrization conditions to topologically
massive gravity coupled to the electromagnetic field and obtain a family of
plane-fronted wave solutions.


title: Semi-Dense 3D Semantic Mapping from Monocular SLAM

abstract:
  The bundle of geometry and appearance in computer vision has proven to be a
promising solution for robots across a wide variety of applications. Stereo
cameras and RGB-D sensors are widely used to realise fast 3D reconstruction and
trajectory tracking in a dense way. However, they lack flexibility of seamless
switch between different scaled environments, i.e., indoor and outdoor scenes.
In addition, semantic information are still hard to acquire in a 3D mapping. We
address this challenge by combining the state-of-art deep learning method and
semi-dense Simultaneous Localisation and Mapping (SLAM) based on video stream
from a monocular camera. In our approach, 2D semantic information are
transferred to 3D mapping via correspondence between connective Keyframes with
spatial consistency. There is no need to obtain a semantic segmentation for
each frame in a sequence, so that it could achieve a reasonable computation
time. We evaluate our method on indoor/outdoor datasets and lead to an
improvement in the 2D semantic labelling over baseline single frame
predictions.


title:
Resource Allocation in Wireless Powered Relay Networks: A Bargaining
  Game Approach

abstract:
  Simultaneously information and power transfer in mobile relay networks have
recently emerged, where the relay can harvest the radio frequency (RF) energy
and then use this energy for data forwarding and system operation. Most of the
previous works do not consider that the relay may have its own objectives, such
as using the harvested energy for its own transmission instead of maximizing
transmission of the network. Therefore, in this paper, we propose a Nash
bargaining approach to balance the information transmission efficiency of
source-destination pairs and the harvested energy of the relay in a wireless
powered relay network with multiple source-destination pairs and one relay. We
analyze and prove that the Nash bargaining problem has several desirable
properties such as the discreteness and quasi-concavity, when it is decomposed
into three sub-problems: the energy transmission power optimization, the power
control for data transmission and the time division between energy transmission
and data transmission. Based on the theoretical analysis, we propose an
alternating power control and time division algorithm to find a suboptimal
solution. Simulation results clearly show and demonstrate the properties of the
problem and the convergence of our algorithm.


title:
Commonsense Knowledge Enhanced Embeddings for Solving Pronoun
  Disambiguation Problems in Winograd Schema Challenge

abstract:
  In this paper, we propose commonsense knowledge enhanced embeddings (KEE) for
solving the Pronoun Disambiguation Problems (PDP). The PDP task we investigate
in this paper is a complex coreference resolution task which requires the
utilization of commonsense knowledge. This task is a standard first round test
set in the 2016 Winograd Schema Challenge. In this task, traditional linguistic
features that are useful for coreference resolution, e.g. context and gender
information, are no longer effective anymore. Therefore, the KEE models are
proposed to provide a general framework to make use of commonsense knowledge
for solving the PDP problems. Since the PDP task doesn't have training data,
the KEE models would be used during the unsupervised feature extraction
process. To evaluate the effectiveness of the KEE models, we propose to
incorporate various commonsense knowledge bases, including ConceptNet, WordNet,
and CauseCom, into the KEE training process. We achieved the best performance
by applying the proposed methods to the 2016 Winograd Schema Challenge. In
addition, experiments conducted on the standard PDP task indicate that, the
proposed KEE models could solve the PDP problems by achieving 66.7% accuracy,
which is a new state-of-the-art performance.


title:
Predicted Realization of Cubic Dirac Fermion in Quasi-One-Dimensional
  Transition-Metal MonoChalcogenides

abstract:
  We show that the previously predicted Fermion particle that has no analogue
in the standard model of particle theory - the cubically dispersed Dirac
semimetal (CDSM) - is realized in a specific, stable solid state system that
has been made years ago, but was not appreciated to host such a unique Fermion,
composed of six Weyl Fermions, 3 with left-handed and 3 with right-handed
chirality. We identified the crystal symmetry constraints and found the space
group P63/m as one of the two that can support a CDSM, of which the
characteristic band crossing has linear dispersion along the principle axis but
cubic dispersion in the plane perpendicular to it. We then conducted a material
search using density functional theory identifying a group of
quasi-one-dimensional molybdenum mono-chalcogenide compounds A(MoX)3 (A = Na,
K, Rb, In, Tl, X = S, Se, Te) as ideal CDSM candidates. Studying the stability
of the A(MoX)3 family reveals a few candidates such as Rb(MoTe)3 and Tl(MoTe)3
that are predicted to be resilient to Peierls distortion, thus retaining the
metallic character. The combination of one-dimensionality and metallic nature
in this family provides a platform for unusual optical signature - polarization
dependent metallic vs insulating response.


title: A tropical isoperimetric inequality

abstract:
  We introduce tropical analogues of the notion of volume of polytopes, leading
to a tropical version of the (discrete) classical isoperimetric inequality. The
planar case is elementary, but a higher-dimensional generalization leads to an
interesting class of ordinary convex polytopes, characterizing the equality
case in the isoperimetric inequality. This study is motivated by open
complexity questions concerning linear optimization and its tropical analogs.


title: Accelerated Variance Reduced Block Coordinate Descent

abstract:
  Algorithms with fast convergence, small number of data access, and low
per-iteration complexity are particularly favorable in the big data era, due to
the demand for obtaining \emph{highly accurate solutions} to problems with
\emph{a large number of samples} in \emph{ultra-high} dimensional space.
Existing algorithms lack at least one of these qualities, and thus are
inefficient in handling such big data challenge. In this paper, we propose a
method enjoying all these merits with an accelerated convergence rate
$O(\frac{1}{k^2})$. Empirical studies on large scale datasets with more than
one million features are conducted to show the effectiveness of our methods in
practice.


title:
Energy-Based Adaptive Multiple Access in LPWAN IoT Systems with Energy
  Harvesting

abstract:
  This paper develops a control framework for a network of energy harvesting
nodes connected to a Base Station (BS) over a multiple access channel. The
objective is to adapt their transmission strategy to the state of the network,
including the energy available to the individual nodes. In order to reduce the
complexity of control, an optimization framework is proposed where energy
storage dynamics are replaced by dynamic average power constraints induced by
the time correlated energy supply, thus enabling lightweight and flexible
network control. Specifically, the BS adapts the packet transmission
probability of the "active" nodes (those currently under a favorable energy
harvesting state) so as to maximize the average long-term throughput, under
these dynamic average power constraints. The resulting policy takes the form of
the packet transmission probability as a function of the energy harvesting
state and number of active nodes. The structure of the throughput-optimal
genie-aided policy, in which the number of active nodes is known non-causally
at the BS, is proved. Inspired by the genie-aided policy, a Bayesian estimation
approach is presented to address the case where the BS estimates the number of
active nodes based on the observed network transmission pattern. It is shown
that the proposed scheme outperforms by 20% a scheme in which the nodes operate
based on local state information only, and performs well even when energy
storage dynamics are taken into account.


title:
Identities in plactic, hypoplactic, sylvester, Baxter, and related
  monoids

abstract:
  This paper considers whether non-trivial identities are satisfied by certain
`plactic-like' monoids that, like the plactic monoid, are closely connected to
combinatorics. New results show that the hypoplactic, sylvester, Baxter,
stalactic, and taiga monoids satisfy identities, and indeed give shortest
identities satisfied by these monoids. The existing state of knowledge is
discussed for the plactic monoid and left and right patience sorting monoids.


title:
Combinatorics of cyclic shifts in plactic, hypoplactic, sylvester, and
  related monoids

abstract:
  The cyclic shift graph of a monoid is the graph whose vertices are elements
of the monoid and whose edges link elements that differ by a cyclic shift. For
certain monoids connected with combinatorics, such as the plactic monoid (the
monoid of Young tableaux) and the sylvester monoid (the monoid of binary search
trees), connected components consist of elements that have the same evaluation
(that is, contain the same number of each generating symbol). This paper
discusses new results on the diameters of connected components of the cyclic
shift graphs of the finite-rank analogues of these monoids, showing that the
maximum diameter of a connected component is dependent only on the rank. The
proof techniques are explained in the case of the sylvester monoid.


title:
Higher order semi-implicit schemes for linear advection equation on
  Cartesian grids with numerical stability analysis

abstract:
  A new class of semi-implicit numerical schemes for linear advection equation
on Cartesian grids is derived that is inspired by so-called $\kappa$-schemes
used with fully explicit discretizations for this type of problems. Opposite to
fully explicit $\kappa$-scheme the semi-implicit variant is unconditionally
stable in one-dimensional case and it preserves second order accuracy for
dimension by dimension extension in higher dimensional cases. We discuss von
Neumann stability conditions numerically for all numerical schemes. Using
so-called Corner Transport Upwind extension of two-dimensional semi-implicit
scheme with a special choice of $\kappa$ parameters, a second order accurate
method is obtained for which numerical unconditional stability can be shown for
variable velocity and the third order accuracy can be proved for constant
velocity. Several numerical experiments illustrate the properties of
semi-implicit schemes for chosen examples.


title:
pi-pi Stacking between Polyaromatic Hydrocarbon Sheets beyond Dispersion
  Interactions

abstract:
  High level ab initio calculations ranging from coupled cluster methods
including explicitly correlated approaches to standard second order
M{\o}ller-Plesset theory using spin scaling (SOS-MP2) have been performed on
sandwich and slipped parallel dimer structures of a series of quasi
one-dimensional acenes and on two-dimensional sheets containing the series
pyrene to coronene encircled with two layers of benzene rings. Sandwich
(graphitic AA type) and slipped parallel (AB type) structures were considered
and, within given symmetry restrictions, full geometry optimizations were
performed. Basis set superposition effects have been considered. The computed
geometries show a significant biconcave deviation of the twodimensional sheets
from planarity with the central intersheet C...C distances considerably smaller
that van der Waals distances. The computed intersheet binding energy per carbon
atom extrapolated for N ->$\infty$ of -74.3 meV (1.713 kcal/mol)/atom agrees
quite well with the experimental defoliation energy of -52 meV (1.199
kcal/mol)/atom (-67 meV (1.545 kcal/mol)/carbon atom without corrections for H
binding contributions) for polyaromatic hydrocarbons (PAHs) from graphite. A
limited investigation of density functional theory (DFT) calculations using
empirical dispersion contributions has been performed also showing a
significant underbinding character of the D3 method. For most of the DFT
variants investigated the graphene sheet models retain a quasi-planar structure
in strong contrast to the aforementioned SOS-MP2 results.


title: The Chermak-Delgado lattice of ZM-groups

abstract:
  In this note we prove that the Chermak-Delgado lattice of a ZM-group is a
chain of length $0$. A similar conclusion is obtained for all dihedral groups
$D_{2m}$ with $m\neq 4$.


title: Planning system for deliveries in Medell\'in

abstract:
  Here we present the implementation of an application capable of planning the
shortest delivery route in the city of Medell\'in, Colombia. We discuss the
different approaches to this problem which is similar to the famous Traveling
Salesman Problem (TSP), but differs in the fact that, in our problem, we can
visit each place (or vertex) more than once. Solving this problem is important
since it would help people, especially stores with delivering services, to save
time and money spent in fuel, because they can plan any route in an efficient
way.


title: Integral chains and Bousfield-Kan completion

abstract:
  Working in the Arone-Ching framework for homotopical descent, it follows that
the Bousfield-Kan completion map with respect to integral homology is the unit
of a derived adjunction. We prove that this derived adjunction, comparing
spaces with coalgebra complexes over the associated integral homology comonad,
via integral chains, can be turned into a derived equivalence by replacing
spaces with the full subcategory of simply connected spaces. In particular,
this provides an integral chains characterization of the homotopy type of
simply connected spaces.


title: Tests for scale changes based on pairwise differences

abstract:
  In many applications it is important to know whether the amount of
fluctuation in a series of observations changes over time. In this article, we
investigate different tests for detecting change in the scale of
mean-stationary time series. The classical approach based on the CUSUM test
applied to the squared centered, is very vulnerable to outliers and impractical
for heavy-tailed data, which leads us to contemplate test statistics based on
alternative, less outlier-sensitive scale estimators.
  It turns out that the tests based on Gini's mean difference (the average of
all pairwise distances) or generalized Qn estimators (sample quantiles of all
pairwise distances) are very suitable candidates. They improve upon the
classical test not only under heavy tails or in the presence of outliers, but
also under normality. An explanation for this at first counterintuitive result
is that the corresponding long-run variance estimates are less affected by a
scale change than in the case of the sample-variance-based test.
  We use recent results on the process convergence of U-statistics and
U-quantiles for dependent sequences to derive the limiting distribution of the
test statistics and propose estimators for the long-run variance. We perform a
simulations study to investigate the finite sample behavior of the test and
their power. Furthermore, we demonstrate the applicability of the new
change-point detection methods at two real-life data examples from hydrology
and finance.


title: Sequential Solutions in Machine Scheduling Games

abstract:
  We consider the classical machine scheduling, where $n$ jobs need to be
scheduled on $m$ machines, and where job $j$ scheduled on machine $i$
contributes $p_{i,j}\in \mathbb{R}$ to the load of machine $i$, with the goal
of minimizing the makespan, i.e., the maximum load of any machine in the
schedule. We study inefficiency of schedules that are obtained when jobs arrive
sequentially one by one, and the jobs choose themselves the machine on which
they will be scheduled, aiming at being scheduled on a machine with small load.
We measure the inefficiency of a schedule as the ratio of the makespan obtained
in the worst-case equilibrium schedule, and of the optimum makespan. This ratio
is known as the \emph{sequential price of anarchy}. We also introduce two
alternative inefficiency measures, which allow for a favorable choice of the
order in which the jobs make their decisions. As our first result, we disprove
the conjecture of Hassin and Yovel claiming that the sequential price of
anarchy for $m=2$ machines is at most 3. We show that the sequential price of
anarchy grows at least linearly with the number $n$ of players, i.e., we show
that $SPoA = \Omega(n)$. Furthermore, we show that there exists an order of the
jobs, resulting in makespan that is at most linearly larger than the optimum
makespan. To the end, we show that if an authority can change the order of the
jobs adaptively to the decisions made by the jobs so far (but cannot influence
the decisions of the jobs), then there exists an adaptive ordering in which the
jobs end up in an optimum schedule.


title:
Generalized $\mathbf{W^{1,1}}$-Young measures and relaxation of problems
  with linear growth

abstract:
  We completely characterize generalized Young measures generated by sequences
of gradients of maps from $W^{1,1}(\Omega;\R^M)$ where $\Omega\subset\R^N$.
This extends and completes previous analysis by Kristensen and Rindler where
concentrations of the sequence of gradients at the boundary of $\Omega$ were
excluded. We apply our results to relaxation of non-quasiconvex variational
problems with linear growth at infinity. We also link our characterization to
Sou\v{c}ek spaces \cite{soucek}, an extension of $W^{1,1}(\Omega;\R^M)$ where
gradients are considered as measures on $\bar\Omega$.


title:
Molecular dynamics simulation of melting of finite and inifinite size
  graphene

abstract:
  We investigate the melting phenomena of pristine, free-standing infinite and
finite size graphene sheets via molecular dynamics simulation using AIREBO
potential as implemented in the LAMMPS package. In our simulations, the
temperature of the systems under investigation are systematically heated up
using two independent heating protocols so that the resultant melting
temperatures from both schemes can be checked against each other for
consistency. The melting temperature of infinite graphene sheet is obtained by
following three independent computational experiments. In the first experiment,
we simulate the melting of various finite size graphenes, and then determine
the melting temperature of infinite graphene sheet as the temperature at which
the finite graphenes asymptotically grow in size. In the second experiment, we
simulate the melting of infinite single-wall carbon-nanotubes (SWCNTs) with
different radius, and then determine the melting temperature of infinite
graphene sheet as the temperature at which the radius of SWCNTs asymptotically
grows in size. In the third experiment, we heat up an infinite graphene that is
formed by constructing a rectangular supercell which is subjected to periodic
boundary condition at it sides. Melting temperature for infinite graphene
obtained based on the first approach yields $\sim$ 5799 K $\pm$ 22 K. The
second approach yield $\sim$5302 K $\pm$ 36 K, whereas $\sim$5355 $\pm$ 140 K
from the third. There is an apparent disparity between the results from the
first experiment and that of the second and third experiments due to
differences in the technical details in these MD simulations. We cautiously
conclude that, based on the consistency of the data of the second and third
experiments, that a free-standing infinite graphene sheet melts at the
temperature of 5302 K $\pm$ 36 K, using AIREBO forcefield.


title:
Black holes with ${\mathfrak {su}}(N)$ gauge field hair and
  superconducting horizons

abstract:
  We present new planar dyonic black hole solutions of the ${\mathfrak
{su}}(N)$ Einstein-Yang-Mills equations in asymptotically anti-de Sitter
space-time, focussing on ${\mathfrak {su}}(2)$ and ${\mathfrak {su}}(3)$ gauge
groups. The magnetic part of the gauge field forms a condensate close to the
planar event horizon. We compare the free energy of a non-Abelian hairy black
hole with that of an embedded Reissner-Nordstr\"om-anti-de Sitter (RN-AdS)
black hole having the same Hawking temperature and electric charge. We find
that the hairy black holes have lower free energy. We present evidence that
there is a phase transition at a critical temperature, above which the only
solutions are embedded RN-AdS black holes. At the critical temperature, an
RN-AdS black hole can decay into a hairy black hole, and it is
thermodynamically favourable to do so. Working in the probe limit, we compute
the frequency-dependent conductivity, and find that enlarging the gauge group
from ${\mathfrak {su}}(2)$ to ${\mathfrak {su}}(3)$ eliminates a divergence in
the conductivity at nonzero frequency.


title: A note on lower nil M-Armendariz rings

abstract:
  In this article, we prove some results for lower nil M-Armendariz ring. Let M
be a strictly totally ordered monoid and I be a semicommutative ideal of R. If
R/I is a lower nil M-Armendariz ring, then R is lower nil M-Armendariz.
Similarly, for above M, if I is 2-primal with N_{*}(R) subset of I and R/I is
M-Armendariz, then R is a lower nil M-Armendariz ring. Further, we observe that
if M is a monoid and N a u.p.-monoid where R is a 2-primal M-Armendariz ring,
then R[N] is a lower nil M-Armendariz ring.


title:
Approximate explicit model predictive control via piecewise nonlinear
  system identification

abstract:
  This article presents an identification methodology to capture general
relationships, with application to piecewise nonlinear approximations of model
predictive control for constrained (non)linear systems. The mathematical
formulation takes, at each iteration, the form of a constrained linear (or
quadratic) optimization problem that is mathematically feasible as well as
numerically tractable. The efficiency of the devised methodology is
demonstrated via two industrial applications. Results suggest the possibility
to achieve high approximate precision with limited number of regions, leading
to a significant reduction in computation time when compared to the
state-of-the-art implicit model predictive control solvers.


title:
Reconstruction of halo power spectrum from redshift-space galaxy
  distribution: cylinder-grouping method and halo exclusion effect

abstract:
  The peculiar velocity field measured by redshift-space distortions (RSD) in
galaxy surveys provides a unique probe of the growth of large-scale structure.
However, systematic effects arise when including satellite galaxies in the
clustering analysis. Since satellite galaxies tend to reside in massive halos
with a greater halo bias, the inclusion boosts the clustering power. In
addition, virial motions of the satellite galaxies cause a significant
suppression of the clustering power due to nonlinear RSD effects. We develop a
novel method to recover the redshift-space power spectrum of halos from the
observed galaxy distribution by minimizing the contamination of satellite
galaxies. The cylinder grouping method (CGM) we study effectively excludes
satellite galaxies from a galaxy sample. However, we find that this technique
produces apparent anisotropies in the reconstructed halo distribution over all
the scales which mimic RSD. On small scales, the apparent anisotropic
clustering is caused by exclusion of halos within the anisotropic cylinder used
by the CGM. On large scales, the misidentification of different halos in the
large-scale structures, aligned along the line-of-sight, into the same CGM
group, causes the apparent anisotropic clustering via their cross-correlation
with the CGM halos. We construct an empirical model for the CGM halo power
spectrum, which includes correction terms derived using the CGM window function
at small scales as well as the linear matter power spectrum multiplied by a
simple anisotropic function at large scales. We apply this model to a mock
galaxy catalog at z=0.5, designed to resemble SDSS-III BOSS CMASS galaxies, and
find that our model can predict both the monopole and quadrupole power spectra
of the host halos up to k<0.5 h/Mpc to within 5%.


title: Efficiency of Wave-Driven Rigid Body Rotation Toroidal Confinement

abstract:
  The compensation of vertical drifts in toroidal magnetic fields through a
wave-driven poloidal rotation is compared to compensation through the wave
driven toroidal current generation to support the classical magnetic rotational
transform. The advantages and drawbacks associated with the sustainment of a
radial electric field are compared with those associated with the sustainment
of a poloidal magnetic field both in terms of energy content and power
dissipation. The energy content of a radial electric field is found to be
smaller than the energy content of a poloidal magnetic field for a similar set
of orbits. The wave driven radial electric field generation efficiency is
similarly shown, at least in the limit of large aspect ratio, to be larger than
the efficiency of wave-driven toroidal current generation.


title: A parallel workload has extreme variability

abstract:
  In both high-performance computing (HPC) environments and the public cloud,
the duration of time to retrieve or save your results is simultaneously
unpredictable and important to your over all resource budget. It is generally
accepted ("Google: Taming the Long Latency Tail - When More Machines Equals
Worse Results", Todd Hoff, highscalability.com 2012), but without a robust
explanation, that identical parallel tasks do take different durations to
complete -- a phenomena known as variability. This paper advances understanding
of this topic. We carefully choose a model from which system-level complexity
emerges that can be studied directly. We find that a generalized extreme value
(GEV) model for variability naturally emerges. Using the public cloud, we find
real-world observations have excellent agreement with our model. Since the GEV
distribution is a limit distribution this suggests a universal property of
parallel systems gated by the slowest communication element of some sort.
Hence, this model is applicable to a variety of processing and IO tasks in
parallel environments. These findings have important implications, ranging from
characterizing ideal performance for parallel codes to detecting degraded
behaviour at extreme scales.


title:
Dynamic instabilities in the kinetics of growth and disassembly of
  microtubules

abstract:
  Dynamic instability of microtubules is considered using frameworks of
non-linear thermodynamics and non-equilibrium reaction-diffusion systems.
Stochastic assembly/disassembly phases in the polymerization dynamics of
microtubules are treated as a result of collective clusterization of
microdefects (holes in structure). The model explains experimentally observed
power law dependence of catastrophe frequency from the microtubule growth rate.
Additional reaction-diffusion-precipitation model is developed to account for
kinetic limitations in microtubule dynamics. It is shown that large scale
periodic microtubules length fluctuations are accompanied by concentration
autowaves. We built corresponding parametric diagram mapping areas of
stationary, non-stationary and metastable solutions. The loss of stability for
the stationary solutions happens through bifurcation of Andronov-Hopf. Using
parametric diagram we classify cytostatic effect of microtubule stabilizing
drugs in four major classes and analyze their compatibility and possible
synergistic effect for cancer treatment therapy.


title:
Morita equivalence of C*-correspondences passes to the related operator
  algebras

abstract:
  We revisit a central result of Muhly and Solel on operator algebras of
C*-correspondences. We prove that (possibly non-injective) strongly Morita
equivalent C*-correspondences have strongly Morita equivalent relative
Cuntz-Pimsner C*-algebras. The same holds for strong Morita equivalence (in the
sense of Blecher, Muhly and Paulsen) and strong $\Delta$-equivalence (in the
sense of Eleftherakis) for the related tensor algebras. In particular, we
obtain stable isomorphism of the operator algebras when the equivalence is
given by a $\sigma$-TRO. As an application we show that strong Morita
equivalence coincides with strong $\Delta$-equivalence for tensor algebras of
aperiodic C*-correspondences.


title: Asymmetric combination of logics is functorial: A survey

abstract:
  Asymmetric combination of logics is a formal process that develops the
characteristic features of a specific logic on top of another one. Typical
examples include the development of temporal, hybrid, and probabilistic
dimensions over a given base logic. These examples are surveyed in the paper
under a particular perspective - that this sort of combination of logics
possesses a functorial nature. Such a view gives rise to several interesting
questions. They range from the problem of combining translations (between
logics), to that of ensuring property preservation along the process, and the
way different asymmetric combinations can be related through appropriate
natural transformations.


title:
Convergence and error estimates for the Lagrangian based Conservative
  Spectral method for Boltzmann Equations

abstract:
  We develop error estimates for the semi-discrete conservative spectral method
for the approximation of the elastic and inelastic space homogeneous Boltzmann
equation introduced by the authors in \cite{GT09}. In addition we study the
long time convergence of such semi-discrete solution to equilibrium Maxwellian
distribution that conserves the mass, momentum and energy associated to the
initial data. The numerical method is based on the Fourier transform of the
collisional operator and a Lagrangian optimization correction that enforces the
collision invariants, namely conservation of mass, momentum and energy in the
elastic case, and just mass and momentum in the inelastic one. We present a
detailed semi-discrete analysis on convergence of the proposed numerical method
which includes the $L^{1}-L^{2}$ theory for the scheme. This analysis allows us
to present, additionally, convergence in Sobolev spaces and convergence to
equilibrium for the numerical approximation. The results of this work answer a
long standing open problem posed by Cercignani et al. in \cite[Chapter 12]{CIP}
about finding error estimates for a numerical scheme associated to the
Boltzmann equation, as well as showing the semi-discrete numerical solution
converges to the equilibrium Maxwellian distribution associated to the initial
value problem.

categories: math.NA cond-mat.stat-mech cs.NA math-ph math.MP


title: Weak tangents and level sets of Takagi functions

abstract:
  In this paper we study some properties of Takagi functions and their level
sets. We show that for Takagi functions $T_{a,b}$ with parameters $a,b$ such
that $ab$ is a root of a Littlewood polynomial, there exist large level sets.
As a consequence we show that for some parameters $a,b$, the Assouad dimension
of graphs of $T_{a,b}$ is strictly larger than their upper box dimension. In
particular we can find weak tangents of those graphs with large Hausdorff
dimension, larger than the upper box dimension of the graphs.


title: On a class of half-factorial domains

abstract:
  Let $R$ be an integral domain. For elements $a,b \in R$, let $[a,b]$ denote
their greatest common divisor, if it exists. We say that $R$ has the Z-property
if whenever $a,b,c,d$ and $e$ are nonzero nonunits of $R$ such that $abc=de$,
then $[ab,d] \neq 1$ or $[ab,e] \neq 1$. The purpose of this paper is to study
this property. The atomic integral domains that have this property constitute a
class of half-factorial domains. Also, it is known that $R$ must have this
property in order for the polynomial ring $R[x]$ to be half-factorial. We use
it to give a characterization of half-factorial polynomial rings in the case
where every $v$-ideal is $v$-generated by two elements. We also show that if
$R$ is a Krull domain with this property, then $R$ has torsion class group.


title:
Wind Energy in the United Kingdom: Modelling the Effect of Increases in
  Installed Capacity on Generation Efficiency

abstract:
  The decision by the United Kingdom (UK) government in 2007 that the country
should build a 33GW wind fleet, capable of generating 25 percent of the UK
electricity requirement, was controversial. Proponents argued that it was the
most attractive means of lowering the UK greenhouse gas emissions, whereas
opponents noted that it would result in an unnecessary and burdensome
additional expense to industry and households. Subsequently there have been
calls for the wind fleet target to be further increased to perhaps 50 percent
of demand. Although the National Grid has had little difficulty in
accommodating the current output of about 10 percent of the total demand on the
grid, this will not be the case for a substantially larger wind fleet. When the
wind blows strongly, turbines shed wind which is surplus to demand, leading to
significant reductions in generating efficiency. The purpose of the research
described in this paper has been to develop a method for investigating the
likely performance of future large wind fleets. The method relies on the use of
mathematical models based on National Grid records for 2013 to 2015, each year
being separately analysed. It was found that the incremental load factor of the
wind fleet will be reduced to 63 percent of its current level should the wind
fleet increase from its current size of 14GW to 35GW, assuming a base load of
15GW


title: Recognizing and Eliciting Weakly Single Crossing Profiles on Trees

abstract:
  We introduce and study the weakly single-crossing domain on trees which is a
generalization of the well-studied single-crossing domain in social choice
theory. We design a polynomial-time algorithm for recognizing preference
profiles which belong to this domain. We then develop an efficient elicitation
algorithm for this domain which works even if the preferences can be accessed
only sequentially and the underlying single-crossing tree structure is not
known beforehand. We also prove matching lower bound on the query complexity of
our elicitation algorithm when the number of voters is large compared to the
number of candidates. We also prove a lower bound of $\Omega(m^2\log n)$ on the
number of queries that any algorithm needs to ask to elicit single crossing
profile when random queries are allowed. This resolves an open question in an
earlier paper and proves optimality of their preference elicitation algorithm
when random queries are allowed.


title:
Toward real-time high-fidelity simulation using integral boundary layer
  modeling

abstract:
  One of the greatest challenges to using large-eddy simulations (LES) in
engineering applications is the large number of grid points required near
walls. To mitigate this issue, researchers often couple LES with a simplified
model of the flow close to the wall, known as the wall model. One feature
common to most wall models is that the first few (about 3) grid points must be
located below the inviscid log-layer, and the grid must have near-isotropic
resolution near the wall. Hence, wall-modeled LES may still require a large
number of grid points in both the wall-normal and span-wise directions. Because
of these requirements, wall-modeled LES is still unfeasible in many
applications. We present a new formulation of wall-modeled LES that is being
developed to address this issue. In this formulation, LES is used to solve only
for the features of the velocity field that can be adequately represented on
the LES grid. The effects of the unresolved features are captured by imposing
an integral balance of kinetic energy in the near-wall region. This integral
energy balance translates into a dynamic partial differential equation defined
on the walls, which is coupled to the LES equations. We discuss details of the
new formulation and present results obtained in laminar channel flows.


title: A Feynman-Kac formula for stochastic Dirichlet problems

abstract:
  A representation formula for solutions of stochastic partial differential
equations with Dirichlet boundary conditions is proved. The scope of our
setting is wide enough to cover the general situation when the backward
characteristics that appear in the usual formulation are not even defined in
the It\^o sense.


title: On the $\mathcal{NP}$-hardness of GRacSim Drawing and k-SEFE Problems

abstract:
  We study the complexity of two problems in simultaneous graph drawing. The
first problem, GRacSim Drawing, asks for finding a simultaneous geometric
embedding of two graphs such that only crossings at right angles are allowed.
The second problem, k-SEFE, is a restricted version of the topological
simultaneous embedding with fixed edges (SEFE) problem, for two planar graphs,
in which every private edge may receive at most $k$ crossings, where $k$ is a
prescribed positive integer. We show that GRacSim Drawing is
$\mathcal{NP}$-hard and that k-SEFE is $\mathcal{NP}$-complete. The
$\mathcal{NP}$-hardness of both problems is proved using two similar reductions
from 3-Partition.


title: On the Mechanism of Homology Search by RecA Protein Filaments

abstract:
  Genetic stability is a key factor in maintaining, survival and reproduction
of biological cells. It relies on many processes, but one of the most important
is a {\it homologous recombination}, in which the repair of breaks in
double-stranded DNA molecules is taking place with a help of several specific
proteins. In bacteria this task is accomplished by RecA proteins that are
active as nucleoprotein filaments formed on single-stranded segments of DNA. A
critical step in the homologous recombination is a search for a corresponding
homologous region on DNA, which is called a {\it homology search}. Recent
single-molecule experiments clarified some aspects of this process, but its
molecular mechanisms remain not well understood. We developed a quantitative
theoretical approach to analyze the homology search. It is based on a
discrete-state stochastic model that takes into account the most relevant
physical-chemical processes in the system. Using a method of first-passage
processes, a full dynamic description of the homology search is presented. It
is found that the search dynamics depends on the degree of extension of DNA
molecules and on the size of RecA nucleoprotein filaments, in agreement with
experimental single-molecule measurements of DNA pairing by RecA proteins. Our
theoretical calculations, supported by extensive Monte Carlo computer
simulations, provide a molecular description of the mechanisms of the homology
search.


title: Learning to Gather Information via Imitation

abstract:
  The budgeted information gathering problem - where a robot with a fixed fuel
budget is required to maximize the amount of information gathered from the
world - appears in practice across a wide range of applications in autonomous
exploration and inspection with mobile robots. Although there is an extensive
amount of prior work investigating effective approximations of the problem,
these methods do not address the fact that their performance is heavily
dependent on distribution of objects in the world. In this paper, we attempt to
address this issue by proposing a novel data-driven imitation learning
framework.
  We present an efficient algorithm, EXPLORE, that trains a policy on the
target distribution to imitate a clairvoyant oracle - an oracle that has full
information about the world and computes non-myopic solutions to maximize
information gathered. We validate the approach on a spectrum of results on a
number of 2D and 3D exploration problems that demonstrates the ability of
EXPLORE to adapt to different object distributions. Additionally, our analysis
provides theoretical insight into the behavior of EXPLORE. Our approach paves
the way forward for efficiently applying data-driven methods to the domain of
information gathering.


title: Linear Logic Properly Displayed

abstract:
  We introduce proper display calculi for intuitionistic, bi-intuitionistic and
classical linear logics with exponentials, which are sound, complete,
conservative, and enjoy cut-elimination and subformula property. Based on the
same design, we introduce a variant of Lambek calculus with exponentials, aimed
at capturing the controlled application of exchange and associativity.
Properness (i.e. closure under uniform substitution of all parametric parts in
rules) is the main interest and added value of the present proposal, and allows
for the smoothest proof of cut-elimination. Our proposal builds on an algebraic
and order-theoretic analysis of linear logic, and applies the guidelines of the
multi-type methodology in the design of display calculi.


title: Topological Materials: Weyl Semimetals

abstract:
  Topological insulators and topological semimetals are both new classes of
quantum materials, which are characterized by surface states induced by the
topology of the bulk band structure. Topological Dirac or Weyl semimetals show
linear dispersion round nodes, termed the Dirac or Weyl points, as the
three-dimensional analogue of graphene. We review the basic concepts and
compare these topological states of matter from the materials perspective with
a special focus on Weyl semimetals. The TaAs family is the ideal materials
class to introduce the signatures of Weyl points in a pedagogical way, from
Fermi arcs to the chiral magneto-transport properties, followed by the hunting
for the type-II Weyl semimetals in WTe2, MoTe2 and related compounds. Many
materials are members of big families and topological properties can be tuned.
As one example, we introduce the multifuntional topological materials, Heusler
compounds, in which both topological insulators and magnetic Weyl semimetals
can be found. Instead of a comprehensive review, this article is expected to
serve as a helpful introduction and summary by taking a snapshot of the quickly
expanding field.


title:
Spin pseudogap in the $S=\frac{1}{2}$ chain material Sr$_2$CuO$_3$ with
  impurities

abstract:
  The low energy magnetic excitation spectrum of the Heisenberg
antiferromagnetic $S = 1/2$ chain system Sr$_2$CuO$_3$ with Ni- and
Ca-impurities is studied by neutron spectroscopy. In all cases, a
defect-induced spectral pseudogap is observed and shown to scale
proportionately to the number of scattering centers in the spin chains.


title:
Advanced Analysis of Quantum Contextuality in a Psychophysical
  Double-Detection Experiment

abstract:
  The results of behavioral experiments typically exhibit inconsistent
connectedness, i.e., they violate the condition known as "no-signaling,"
"no-disturbance," or "marginal selectivity." This prevents one from evaluating
these experiments in terms of quantum contextuality if the latter understood
traditionally (as, e.g., in the Kochen-Specker theorem or Bell-type
inequalities). The Contextuality-by-Default (CbD) theory separates
contextuality from inconsistent connectedness. When applied to quantum physical
experiments that exhibit inconsistent connectedness (due to context-dependent
errors and/or signaling), the CbD computations reveal quantum contextuality in
spite of this. When applied to a large body of published behavioral
experiments, the CbD computations reveal no quantum contextuality: all
context-dependence in these experiments is described by inconsistent
connectedness alone. Until recently, however, experimental analysis of
contextuality was confined to so-called cyclic systems of binary random
variables. Here, we present the results of a psychophysical double-detection
experiment that do not form a cyclic system: their analysis requires that we
use a recent modification of CbD, one that makes the class of noncontextual
systems more restricted. Nevertheless our results once again indicate that when
inconsistent connectedness is taken into account, the system exhibits no
contextuality. KEYWORDS: contextuality, cyclic systems, double-detection,
inconsistent connectedness, psychophysics.


title: Positive definite kernels and boundary spaces

abstract:
  We consider a kernel based harmonic analysis of "boundary," and boundary
representations. Our setting is general: certain classes of positive definite
kernels. Our theorems extend (and are motivated by) results and notions from
classical harmonic analysis on the disk. Our positive definite kernels include
those defined on infinite discrete sets, for example sets of vertices in
electrical networks, or discrete sets which arise from sampling operations
performed on positive definite kernels in a continuous setting.
  Below we give a summary of main conclusions in the paper: Starting with a
given positive definite kernel $K$ we make precise generalized boundaries for
$K$. They are measure theoretic "boundaries." Using the theory of Gaussian
processes, we show that there is always such a generalized boundary for any
positive definite kernel.


title:
Donaldson-Thomas Transformation of Double Bruhat Cells in Semisimple Lie
  Groups

abstract:
  Double Bruhat cells $G^{u,v}$ were studied by Fomin and Zelevinsky. They
provide important examples of cluster algebras and cluster Poisson varieties.
Cluster varieties produce examples of 3d Calabi-Yau categories with stability
conditions, and their Donaldson-Thomas invariants, defined by Kontsevich and
Soibelman, are encoded by a formal automorphism on the cluster variety known as
the Donaldson-Thomas transformation. Goncharov and Shen conjectured in that for
any semisimple Lie group $G$, the Donaldson-Thomas transformation of the
cluster Poisson variety $H\backslash G^{u,v}/H$ is a slight modification of
Fomin and Zelevinsky's twist map. In this paper we prove this conjecture, using
crucially Fock and Goncharov's cluster ensembles and the amalgamation
construction. Our result, combined with the work of Gross, Hacking, Keel, and
Kontsevich, proves the duality conjecture of Fock and Goncharov in the case of
$H\backslash G^{u,v}/H$.


title: New inequalities involving the Geometric-Arithmetic index

abstract:
  Let $G=(V,E)$ be a simple connected graph and $d_i$ be the degree of its
$i$th vertex. In a recent paper [J. Math. Chem. 46 (2009) 1369-1376] the first
geometric-arithmetic index of a graph $G$ was defined as $$GA_1=\sum_{ij\in
E}\frac{2 \sqrt{d_i d_j}}{d_i + d_j}.$$ This graph invariant is useful for
chemical proposes. The main use of $GA_1$ is for designing so-called
quantitative structure-activity relations and quantitative structure-property
relations.
  In this paper we obtain new inequalities involving the geometric-arithmetic
index $GA_1$ and characterize the graphs which make the inequalities tight. In
particular, we improve some known results, generalize other, and we relate
$GA_1$ to other well-known topological indices.


title: Local Master Equation for Small Temperatures

abstract:
  We present a local Master equation for open system dynamics in two forms:
Markovian and non-Markovian. Both have a wider range of validity than the
Lindblad equation investigated by Davies. For low temperatures, they do not
require coupling to be exponentially weak in the system size. If the state
remains a low bond dimension Matrix Product State throughout the evolution, the
local equation can be simulated in time polynomial in system size.


title: Emergent gravity from Eguchi-Kawai reduction

abstract:
  Holographic theories with a local gravitational dual have a number of
striking features. Here I argue that many of these features are controlled by
the Eguchi-Kawai mechanism, which is proposed to be a hallmark of such
holographic theories. Higher-spin holographic duality is presented as a failure
of the Eguchi-Kawai mechanism, and its restoration illustrates the deformation
of higher-spin theory into a proper string theory with a local gravitational
limit. AdS/CFT is used to provide a calculable extension of the Eguchi-Kawai
mechanism to field theories on curved manifolds and thereby introduce
"topological volume independence." Finally, I discuss implications for a
general understanding of the extensivity of the Bekenstein-Hawking-Wald
entropy.


title: Fermi bubble edges: spectrum and diffusion function

abstract:
  Current measurements of the $\gamma$-ray Fermi bubbles (FB) are based on
model-dependent tracers, carry substantial systematic uncertainties, and are at
some tension with each other. We show that gradient filters pick out the FB
edges, which are found to smoothly connect to the bipolar X-ray structure
emanating from the Galactic center, thus supporting the interpretation of the
FBs as a Galactic-scale phenomenon. The sharp edges facilitate a direct,
model-free measurement of the peripheral FB spectrum. The result is strikingly
similar to the full FB-integrated spectrum, softened by a power law of index
$\eta\simeq (0.2\mbox{--}0.3)$. This is naturally explained, in both hadronic
and leptonic models, if cosmic rays are injected at the edge, and diffuse away
preferentially at higher energies $E$. The inferred, averaged diffusion
function in the (more plausible) leptonic model, $D(E)\simeq
10^{29.5}(E/10\mbox{ GeV})^{0.48\pm0.02}\mbox{ cm}^2\mbox{ s}^{-1}$, is
consistent with estimates for Kraichnan-like turbulence. Our results, in
particular the minute spatial variations in $\eta$, indicate that the FB edge
is a strong, Mach $\gtrsim5$, forward shock.


title: Fonctions m\'eromorphes et fonctions th\^eta sur les surfaces de Riemann

abstract:
  Theta functions play a major role in many current researches and are powerful
tools for studying integrable systems. The purpose of this paper is to provide
a short and quick exposition of some aspects of meromorphic theta functions for
compact Riemann surfaces. The study of theta functions will be done via an
analytical approach using meromorphic functions in the framework of Mumford.
Some interesting examples will be given : the classical Kirchhoff equations in
the cases of Clebsch and Lyapunov-Steklov, the Landau-Lifshitz equation and the
sine-Gordon equation.


title: A power consensus algorithm for DC microgrids

abstract:
  A novel power consensus algorithm for DC microgrids is proposed and analyzed.
DC microgrids are networks composed of DC sources, loads, and interconnecting
lines. They are represented by differential-algebraic equations connected over
an undirected weighted graph that models the electrical circuit. A second graph
represents the communication network over which the source nodes exchange
information about the instantaneous powers, which is used to adjust the
injected current accordingly. This give rise to a nonlinear consensus-like
system of differential-algebraic equations that is analyzed via Lyapunov
functions inspired by the physics of the system. We establish convergence to
the set of equilibria consisting of weighted consensus power vectors as well as
preservation of the weighted geometric mean of the source voltages. The results
apply to networks with constant impedance, constant current and constant power
loads.


title:
Patterns of Selection of Human Movements III: Energy Efficiency,
  Mechanical Advantage, and Walking Gait

abstract:
  Human movements are physical processes combining the classical mechanics of
the human body moving in space and the biomechanics of the muscles generating
the forces acting on the body under sophisticated sensory-motor control. One
way to characterize movement performance is through measures of energy
efficiency that relate the mechanical energy of the body and metabolic energy
expended by the muscles. We expect the practical utility of such measures to be
greater when human subjects execute movements that maximize energy efficiency.
We therefore seek to understand if and when subjects select movements with that
maximizing energy efficiency. We proceed using a model-based approach to
describe movements which perform a task requiring the body to add or remove
external mechanical work to or from an object. We use the specific example of
walking gaits doing external mechanical work by pulling a cart, and estimate
the relationship between the avg. walking speed and avg. step length. In the
limit where no external work is done, we find that the estimated maximum energy
efficiency walking gait is much slower than the walking gaits healthy adults
typically select. We then modify the situation of the walking gait by
introducing an idealized mechanical device that creates an adjustable
mechanical advantage. The walking gaits that maximize the energy efficiency
using the optimal mechanical advantage are again much slower than the walking
gaits healthy adults typically select. We finally modify the situation so that
the avg. walking speed is fixed and derive the pattern of the avg. step length
and mechanical advantage that maximize energy efficiency.


title:
Multi-band study of RX J0838-2827 and XMM J083850.4-282759: a new
  asynchronous magnetic cataclysmic variable and a candidate transitional
  millisecond pulsar

abstract:
  In search for the counterpart to the Fermi-LAT source 3FGL J0838.8-2829, we
performed a multi-wavelength campaign, in the X-ray band with Swift and
XMM-Newton, performed infrared, optical (with OAGH, ESO-NTT and IAC80) and
radio (ATCA) observations, as well as analysed archival hard X-ray data taken
by INTEGRAL. We report on three X-ray sources consistent with the position of
the Fermi-LAT source. We confirm the identification of the brightest object, RX
J0838-2827, as a magnetic cataclysmic variable, that we recognize as an
asynchronous system (not associated with the Fermi-LAT source). RX J0838-2827,
is extremely variable in the X-ray and optical bands, and timing analysis
reveals the presence of several periodicities modulating its X-ray and optical
emission. The most evident modulations are interpreted as due to the binary
system orbital period of ~1.64h and the white dwarf spin period of ~1.47h. A
strong flux modulation at ~15h is observed at all energy bands, consistent with
the beat frequency between spin and orbital periods. Optical spectra show
prominent Hbeta, HeI and HeII emission lines Doppler-modulated at the orbital
period and at the beat period. Therefore, RX J0838-2827, accretes through a
diskless configuration and could be either a strongly asynchronous polar or a
rare example of a pre-polar system in its way to reach synchronism. Among the
other two X-ray sources, XMM J083850.4-282759 showed a variable X-ray emission,
with a powerful flare lasting ~600s, similar to what is observed in
transitional millisecond pulsars during the sub-luminous disc state: that would
possibly associate this source with the Fermi-LAT source.


title:
A new proof of scattering below the ground state for the 3d radial
  focusing cubic NLS

abstract:
  We revisit the scattering result of Holmer and Roudenko on the radial
focusing cubic NLS in three space dimensions. Using the radial Sobolev
embedding and a virial/Morawetz estimate, we give a simple proof of scattering
below the ground state that avoids the use of concentration compactness.


title: Self-Calibration and Bilinear Inverse Problems via Linear Least Squares

abstract:
  Whenever we use devices to take measurements, calibration is indispensable.
While the purpose of calibration is to reduce bias and uncertainty in the
measurements, it can be quite difficult, expensive, and sometimes even
impossible to implement. We study a challenging problem called
\emph{self-calibration}, i.e., the task of designing an algorithm for devices
so that the algorithm is able to perform calibration automatically. More
precisely, we consider the setup $\boldsymbol{y} = \mathcal{A}(\boldsymbol{d})
\boldsymbol{x} + \boldsymbol{\epsilon}$ where only partial information about
the sensing matrix $\mathcal{A}(\boldsymbol{d})$ is known and where
$\mathcal{A}(\boldsymbol{d})$ linearly depends on $\boldsymbol{d}$. The goal is
to estimate the calibration parameter $\boldsymbol{d}$ (resolve the uncertainty
in the sensing process) and the signal/object of interests $\boldsymbol{x}$
simultaneously. For three different models of practical relevance, we show how
such a \emph{bilinear} inverse problem, including blind deconvolution as an
important example, can be solved via a simple \emph{linear least squares}
approach. As a consequence, the proposed algorithms are numerically extremely
efficient, thus potentially allowing for real-time deployment. We also present
a variation of the least squares approach, which leads to a~\emph{spectral
method}, where the solution to the bilinear inverse problem can be found by
computing the singular vector associated with the smallest singular value of a
certain matrix derived from the bilinear system. Explicit theoretical
guarantees and stability theory are derived for both techniques; and the number
of sampling complexity is nearly optimal (up to a poly-log factor).
Applications in imaging sciences and signal processing are discussed and
numerical simulations are presented to demonstrate the effectiveness and
efficiency of our approach.


title: Local duality for representations of finite group schemes

abstract:
  A duality theorem for the stable module category of representations of a
finite group scheme is proved. One of its consequences is an analogue of Serre
duality, and the existence of Auslander-Reiten triangles for the
$\mathfrak{p}$-local and $\mathfrak{p}$-torsion subcategories of the stable
category, for each homogeneous prime ideal $\mathfrak{p}$ in the cohomology
ring of the group scheme.


title:
KPII: Cauchy-Jost function, Darboux transformations and totally
  nonnegative matrices

abstract:
  Direct definition of the Cauchy-Jost (known also as Cauchy-Baker-Akhiezer)
function in the case of pure solitonic solution is given and properties of this
function are discussed in detail using the Kadomtsev-Petviashvili II equation
as example. This enables formulation of the Darboux transformations in terms of
the Cauchy-Jost function and classification of these transformations. Action of
Darboux transformations on Grassmanians-i.e., on the space of soliton
parameters-is derived and relation of the Darboux transformations with property
of total nonnegativity of elements of corresponding Grassmanians is discussed.


title: Realistic risk-mitigating recommendations via inverse classification

abstract:
  Inverse classification, the process of making meaningful perturbations to a
test point such that it is more likely to have a desired classification, has
previously been addressed using data from a single static point in time. Such
an approach yields inflated probability estimates, stemming from an implicitly
made assumption that recommendations are implemented instantaneously. We
propose using longitudinal data to alleviate such issues in two ways. First, we
use past outcome probabilities as features in the present. Use of such past
probabilities ties historical behavior to the present, allowing for more
information to be taken into account when making initial probability estimates
and subsequently performing inverse classification. Secondly, following inverse
classification application, optimized instances' unchangeable features
(e.g.,~age) are updated using values from the next longitudinal time period.
Optimized test instance probabilities are then reassessed. Updating the
unchangeable features in this manner reflects the notion that improvements in
outcome likelihood, which result from following the inverse classification
recommendations, do not materialize instantaneously. As our experiments
demonstrate, more realistic estimates of probability can be obtained by
factoring in such considerations.


title:
Electron-nuclear spin dynamics of Ga$^{2+}$ paramagnetic centers probed
  by spin dependent recombination: A master equation approach

abstract:
  Similar to nitrogen-vacancy centers in diamond and impurity atoms in silicon,
interstitial gallium deep paramagnetic centers in GaAsN have been proven to
have useful characteristics for the development of spintronic devices. Among
other interesting properties, under circularly polarized light, gallium centers
in GaAsN act as spin filters that dynamically polarize free and bound electrons
reaching record spin polarizations (100\%). Furthermore, the recent observation
of the amplification of the spin filtering effect under a Faraday configuration
magnetic field has suggested that the hyperfine interaction that couples bound
electrons and nuclei permits the optical manipulation of its nuclear spin
polarization. Even though the mechanisms behind the nuclear spin polarization
in gallium centers are fairly well understood, the origin of nuclear spin
relaxation and the formation of an Overhauser-like magnetic field remain
elusive. In this work we develop a model based on the master equation approach
to describe the evolution of electronic and nuclear spin polarizations of
gallium centers interacting with free electrons and holes. Our results are in
good agreement with existing experimental observations. In regard to the
nuclear spin relaxation, the roles of nuclear dipolar and quadrupolar
interactions are discussed. Our findings show that, besides the hyperfine
interaction, the spin relaxation mechanisms are key to understand the
amplification of the spin filtering effect and the appearance of the
Overhauser-like magnetic field. Based on our model's results we propose an
experimental protocol based on time resolved spectroscopy. It consists of a
pump-probe photoluminescence scheme that would allow the detection and the
tracing of the electron-nucleus flip-flops through time resolved PL
measurements.