title: Self-induced temporal instability from a neutrino antenna

abstract:
  It has been recently shown that the flavor composition of a self-interacting
neutrino gas can spontaneously acquire a time-dependent pulsating component
during its flavor evolution. In this work, we perform a more detailed study of
this effect in a model where neutrinos are assumed to be emitted in a
two-dimensional plane from an infinite line that acts as a neutrino antenna. We
consider several examples with varying matter and neutrino densities and find
that temporal instabilities with various frequencies are excited in a cascade.
We compare the numerical calculations of the flavor evolution with the
predictions of linearized stability analysis of the equations of motion. The
results obtained with these two approaches are in good agreement in the linear
regime, while a dramatic speed-up of the flavor conversions occurs in the
non-linear regime due to the interactions among the different pulsating modes.
We show that large flavor conversions can take place if some of the temporal
modes are unstable for long enough, and that this can happen even if the matter
and neutrino densities are changing, as long as they vary slowly.


title:
Darboux transformations with tetrahedral reduction group and related
  integrable systems

abstract:
  In this paper we derive new two-component integrable differential difference
and partial difference systems by applying a Lax-Darboux scheme to an operator
formed from an ${\mathfrak{sl}}_3({\mathbb{C}})$-based automorphic Lie algebra.
The integrability of the found systems is demonstrated via Lax pairs and
generalised symmetries.


title:
Comparing Properties of Massively Multiplayer Online Worlds and the
  Internet of Things

abstract:
  With the rise of the Internet of Things (IoT), this means recognizing the
need for architectures to handle billions of devices and their interactions. A
virtual world engine at the massively multiplayer scale is a massively
multiplayer online world (MMOW); one thing virtual world engines realized when
going into the scale of MMOs, is the cost of maintaining a potentially
quadratic number of interactions between a massive number of objects, laid out
in a spatial dimension. Research into IoT was fueled by research in wireless
sensor networks, but rather than start from a device perspective, this article
looks at how architectures deal with interacting entities at large scale. The
domain of MMOWs is examined for properties that are affected by scale.
Thereafter the domain of IoT is evaluated to see if each of those properties
are found and how each is handled. By comparing the current state of the art of
MMOWs and IoT, with respect to scalability, the problem of scaling IoT is
explicated, as well as the problem of incorporating an MMOW with IoT into a
pervasive platform. Three case studies of a MMOW interfacing with IoT are
presented in closing.


title:
Vortices with scalar condensates in two-component Ginzburg-Landau
  systems

abstract:
  In a class of two-component Ginzburg-Landau models (TCGL) with a
U(1)$\times$U(1) symmetric potential, vortices with a condensate at their core
may have significantly lower energies than the Abrikosov-Nielsen-Olesen (ANO)
ones. On the example of liquid metallic hydrogen (LMH) above the critical
temperature for protons we show that the ANO vortices become unstable against
core-condensation, while condensate-core (CC) vortices are stable. For LMH the
ratio of the masses of the two types of condensates, $M=m_2/m_1$ is large, and
then as a consequence the energy per flux quantum of the vortices, $E_n/n$
becomes a non-monotonous function of the number of flux quanta, $n$. This leads
to yet another manifestation of neither type 1 nor type 2, (type 1.5)
superconductivity: superconducting and normal domains coexist while various
"giant" vortices form. We note that LMH provides a particularly clean example
of type 1.5 state as the interband coupling between electronic and protonic
Cooper-pairs is forbidden.


title: Incomplete Tambara functors

abstract:
  For a "genuine" equivariant commutative ring spectrum $R$, $\pi_0(R)$ admits
a rich algebraic structure known as a Tambara functor. This algebraic structure
mirrors the structure on $R$ arising from the existence of multiplicative norm
maps. Motivated by the surprising fact that Bousfield localization can destroy
some of the norm maps, in previous work we studied equivariant commutative ring
structures parametrized by $N_\infty$ operads. In a precise sense, these
interpolate between "naive" and "genuine" equivariant ring structures.
  In this paper, we describe the algebraic analogue of $N_\infty$ ring
structures. We introduce and study categories of incomplete Tambara functors,
described in terms of certain categories of bispans. Incomplete Tambara
functors arise as $\pi_0$ of $N_\infty$ algebras, and interpolate between Green
functors and Tambara functors. We classify all incomplete Tambara functors in
terms of a basic structural result about polynomial functors. This
classification gives a conceptual justification for our prior description of
$N_\infty$ operads and also allows us to easily describe the properties of the
category of incomplete Tambara functors.


title: PySpike - A Python library for analyzing spike train synchrony

abstract:
  Understanding how the brain functions is one of the biggest challenges of our
time. The analysis of experimentally recorded neural firing patterns (spike
trains) plays a crucial role in addressing this problem. Here, the PySpike
library is introduced, a Python package for spike train analysis providing
parameter-free and time-scale independent measures of spike train synchrony. It
allows to compute similarity and dissimilarity profiles, averaged values and
distance matrices. Although mainly focusing on neuroscience, PySpike can also
be applied in other contexts like climate research or social sciences. The
package is available as Open Source on Github and PyPI.


title: On homomorphisms between Cremona groups

abstract:
  We look at algebraic embeddings of the Cremona group in $n$ variables
$Cr_n(C)$ to the group of birational transformations $Bir(M)$ of an algebraic
variety $M$. First we study geometrical properties of an example of an
embedding of $Cr_2(C)$ into $Cr_5(C)$ that is due to Gizatullin. In a second
part, we give a full classification of all algebraic embeddings of $Cr_2(C)$
into $Bir(M)$, where $dim(M)=3$, and generalize this result partially to
algebraic embeddings of $Cr_n(C)$ into $Bir(M)$, where $dim(M)=n+1$, for
arbitrary $n\geq 2$. In particular, this yields a classification of all
algebraic $PGL_{n+1}(C)$-actions on smooth projective varieties of dimension
$n+1$ that can be extended to rational actions of $Cr_n(C)$.


title:
X-ray spectral and temporal analysis of Narrow Line Seyfert 1 galaxy Was
  61

abstract:
  We present an analysis of spectrum and variability of the bright reddened
narrow line Seyfert 1 galaxy Was~61 using 90 ks archival {\it XMM-Newton} data.
The X-ray spectrum in 0.2-10 keV can be characterized by an absorbed power-law
plus soft excess and an Fe K$\alpha$ emission line. The power-law spectral
index remains constant during the flux variation. The absorbing material is
mildly ionized, with a column density of 3.2$\times$10$^{21}$ cm$^{-2}$, and
does not appear to vary during the period of the X-ray observation. If the same
material causes the optical reddening (E(B-V)$\simeq$0.6 mag), it must be
located outside the narrow line region with a dust-to-gas ratio similar to the
average Galactic value. We detect significant variations of the Fe K$\alpha$
line during the observational period. A broad Fe K$\alpha$ line at $\simeq$6.7
keV with a width of $\sim$0.6 keV is detected in the low flux segment of the
first 40 ks exposure, and is absent in the spectra of other segments; a narrow
Fe K$\alpha$ emission line $\sim$6.4 keV with a width of $\sim$0.1 keV is
observed in the subsequent 20 ks segment, which has a count rate of 35% higher
and is in the next day. We believe this is due to the change in geometry and
kinematics of the X-ray emitting corona. The temperature and flux of soft X-ray
excess appear to correlate with the flux of the hard power-law component.
Comptonization of disc photons by a warm and optically thick inner disk is
preferred to interpret the soft excess, rather than the ionized reflection.


title: FGK 22 $\mu$m Excess Stars in LAMOST DR2 Stellar Catalog

abstract:
  Since the release of LAMOST (the Large Sky Area Multi-Object Fiber
Spectroscopic Telescope) catalog, we have the opportunity to use the LAMOST DR2
stellar catalog and \emph{WISE All-sky catalog} to search for 22 $\mu$m excess
candidates. In this paper, we present 10 FGK candidates which show an excess in
the infrared (IR) at 22 $\mu$m. The ten sources are all the newly identified 22
$\mu$m excess candidates. Of these 10 stars, 5 stars are F type and 5 stars are
G type. The criterion for selecting candidates is $K_s-[22]_{\mu m}\geq0.387$.
In addition, we present the spectral energy distributions (SEDs) covering
wavelength from optical to mid-infrared band. Most of them show an obvious
excess from 12 $\mu$m band and three candidates even show excess from 3.4
$\mu$m. To characterize the amount of dust, we also estimate the fractional
luminosity of ten 22 $\mu$m excess candidates.


title:
Characteristics of latitude distribution of sunspots and their links to
  solar activity in pre-Greenwich data

abstract:
  We study and compare characteristics of sunspot group latitude distribution
in two catalogs: the extended Greenwich (1874--2014) and Schwabe ones
(1825--1867). We demonstrate that both datasets reveal similar links between
latitude and amplitude characteristics of the 11-year cycle: the latitude
dispersion correlates with the current activity and the mean latitude of
sunspots in the cycle's maximum is proportional to its amplitude, It agrees
with conclusions that we made in previous papers for the Greenwich catalog.
  We show that the latitude properties of sunspot distribution are much more
stable against loss of observational data than traditional amplitude indices of
activity. Therefore, the found links can be used for estimates of quality of
observations and independent normalizing of activity levels in a gappy
pre-Greenwich data. We demonstrate it using the Schwabe catalog as an example.
  In addition, we show that the first part of the Schwabe data probably
contains errors in determination of sunspot latitudes that lead to
overestimation of the sunspot latitude dispersions.


title: Symmetries related to domino tilings on a chessboard

abstract:
  In this paper we study different kinds of symmetries related to the domino
tilings of chessboards.


title:
Speed of sound of a spin balanced Fermi gas with s- and d-wave pairings
  across the BCS-BEC evolution

abstract:
  The authors of a recent paper (PRA \textbf{87}, 013613 (2013)) argued that in
fermionic systems with d-wave pairing the speed of sound is nonanalytic across
the BCS-BEC crossover at the point where the chemical potential vanishes,
regardless of the specific details of the interaction potential. On the
contrary, the numerical results reported here suggest that the speed of sound
across the BCS-BEC evolution of atomic Fermi gases with s- and d-wave pairings
in two-dimensional square lattices is a smooth analytic function at the
vanishing chemical potential.


title:
Modeling dynamical scalarization with a resummed post-Newtonian
  expansion

abstract:
  Despite stringent constraints set by astrophysical observations, there remain
viable scalar-tensor theories that could be distinguished from general
relativity with gravitational-wave detectors. A promising signal predicted in
these alternative theories is dynamical scalarization, which can dramatically
affect the evolution of neutron-star binaries near merger. Motivated by the
successful treatment of spontaneous scalarization, we develop a formalism that
partially resums the post-Newtonian expansion to capture dynamical
scalarization in a mathematically consistent manner. We calculate the
post-Newtonian order corrections to the equations of motion and scalar mass of
a binary system. Through comparison with quasi-equilibrium configuration
calculations, we verify that this new approximation scheme can accurately
predict the onset and magnitude of dynamical scalarization.


title: New Lower Bounds for van der Waerden Numbers Using Distributed Computing

abstract:
  This paper provides new lower bounds for van der Waerden numbers. The number
$W(k,r)$ is defined to be the smallest integer $n$ for which any $r$-coloring
of the integers $0 \ldots, n-1$ admits monochromatic arithmetic progression of
length $k$; its existence is implied by van der Waerden's Theorem. We exhibit
$r$-colorings of $0\ldots n-1$ that do not contain monochromatic arithmetic
progressions of length $k$ to prove that $W(k, r)>n$. These colorings are
constructed using existing techniques. Rabung's method, given a prime $p$ and a
primitive root $\rho$, applies a color given by the discrete logarithm base
$\rho$ mod $r$ and concatenates $k-1$ copies. We also used Herwig et al's
Cyclic Zipper Method, which doubles or quadruples the length of a coloring,
with the faster check of Rabung and Lotts. We were able to check larger primes
than previous results, employing around 2 teraflops of computing power for 12
months through distributed computing by over 500 volunteers. This allowed us to
check all primes through 950 million, compared to 10 million by Rabung and
Lotts. Our lower bounds appear to grow roughly exponentially in $k$. Given that
these constructions produce tight lower bounds for known van der Waerden
numbers, this data suggests that exact van der Waerden Numbers grow
exponentially in $k$ with ratio $r$ asymptotically, which is a new conjecture,
according to Graham.


title:
Exact short-time height distribution in 1D KPZ equation and edge
  fermions at high temperature

abstract:
  We consider the early time regime of the Kardar-Parisi-Zhang (KPZ) equation
in $1+1$ dimensions in curved (or droplet) geometry. We show that for short
time $t$, the probability distribution $P(H,t)$ of the height $H$ at a given
point $x$ takes the scaling form $P(H,t) \sim \exp{\left(-\Phi_{\rm
drop}(H)/\sqrt{t} \right)}$ where the rate function $\Phi_{\rm drop}(H)$ is
computed exactly. While it is Gaussian in the center, i.e., for small $H$, the
PDF has highly asymmetric non-Gaussian tails which we characterize in detail.
This function $\Phi_{\rm drop}(H)$ is surprisingly reminiscent of the large
deviation function describing the stationary fluctuations of finite size models
belonging to the KPZ universality class. Thanks to a recently discovered
connection between KPZ and free fermions, our results have interesting
implications for the fluctuations of the rightmost fermion in a harmonic trap
at high temperature and the full couting statistics at the edge.

categories: cond-mat.stat-mech cond-mat.dis-nn math-ph math.MP math.PR


title: The Status Gradient of Trends in Social Media

abstract:
  An active line of research has studied the detection and representation of
trends in social media content. There is still relatively little understanding,
however, of methods to characterize the early adopters of these trends: who
picks up on these trends at different points in time, and what is their role in
the system? We develop a framework for analyzing the population of users who
participate in trending topics over the course of these topics' lifecycles.
Central to our analysis is the notion of a "status gradient", describing how
users of different activity levels adopt a trend at different points in time.
Across multiple datasets, we find that this methodology reveals key differences
in the nature of the early adopters in different domains.


title: Template Matching via Densities on the Roto-Translation Group

abstract:
  We propose a template matching method for the detection of 2D image objects
that are characterized by orientation patterns. Our method is based on data
representations via orientation scores, which are functions on the space of
positions and orientations, and which are obtained via a wavelet-type
transform. This new representation allows us to detect orientation patterns in
an intuitive and direct way, namely via cross-correlations. Additionally, we
propose a generalized linear regression framework for the construction of
suitable templates using smoothing splines. Here, it is important to recognize
a curved geometry on the position-orientation domain, which we identify with
the Lie group SE(2): the roto-translation group. Templates are then optimized
in a B-spline basis, and smoothness is defined with respect to the curved
geometry. We achieve state-of-the-art results on three different applications:
detection of the optic nerve head in the retina (99.83% success rate on 1737
images), of the fovea in the retina (99.32% success rate on 1616 images), and
of the pupil in regular camera images (95.86% on 1521 images). The high
performance is due to inclusion of both intensity and orientation features with
effective geometric priors in the template matching. Moreover, our method is
fast due to a cross-correlation based matching approach.


title: Pathwise integration with respect to paths of finite quadratic variation

abstract:
  We study a pathwise integral with respect to paths of finite quadratic
variation, defined as the limit of non-anticipative Riemann sums for
gradient-type integrands. We show that the integral satisfies a pathwise
isometry property, analogous to the well-known Ito isometry for stochastic
integrals. This property is then used to represent the integral as a continuous
map on an appropriately defined vector space of integrands. Finally, we obtain
a pathwise 'signal plus noise' decomposition for regular functionals of an
irregular path with non-vanishing quadratic variation, as a unique sum of a
pathwise integral and a component with zero quadratic variation.


title: The CUORE Cryostat: A 1-Ton Scale Setup for Bolometric Detectors

abstract:
  The cryogenic underground observatory for rare events (CUORE) is a 1-ton
scale bolometric experiment whose detector consists of an array of 988 TeO2
crystals arranged in a cylindrical compact structure of 19 towers. This will be
the largest bolometric mass ever operated. The experiment will work at a
temperature around or below 10 mK. CUORE cryostat consists of a cryogen-free
system based on pulse tubes and a custom high power dilution refrigerator,
designed to match these specifications. The cryostat has been commissioned in
2014 at the Gran Sasso National Laboratories and reached a record temperature
of 6 mK on a cubic meter scale. In this paper, we present results of CUORE
commissioning runs. Details on the thermal characteristics and cryogenic
performances of the system will be also given.


title:
Level Crossing in Random Matrices: I. Random perturbation of a fixed
  matrix

abstract:
  We consider level crossing in a matrix family $H=H_0+\lambda V$ where $H_0$
is a fixed $N\times N$ matrix and $V$ belongs to one of the standard Gaussian
random matrix ensembles. We study the probability distribution of level
crossing points in the complex plane of $\lambda$, for which we obtain a number
of exact, asymptotic and approximate formulas.


title:
Non-Abelian $\nu=1/2$ quantum Hall state in $\Gamma_8$ Valence Band Hole
  Liquid

abstract:
  In search of states with non-Abelian statistics, we explore the fractional
quantum Hall effect in a system of two-dimensional charge carrier holes. We
propose a new method of mapping states of holes confined to a finite width
quantum well in a perpendicular magnetic field to states in a spherical shell
geometry. This method provides single-particle hole states used in exact
diagonalization of systems with a small number of holes in the presence of
Coulomb interactions. An incompressible fractional quantum Hall state emerges
in a hole liquid at the half-filling of the ground state in a magnetic field in
the range of fields where single-hole states cross. This state has a negligible
overlap with the Halperin 331 state, but a significant overlap with the
Moore-Read Pfaffian state. Excited fractional quantum Hall states for small
systems have sizable overlap with non-Abelian excitations of the Moore-Read
Pfaffian state.


title:
Optical Response of Strained- and Unstrained-Silicon Cold-Electron
  Bolometers

abstract:
  We describe the optical characterisation of two silicon cold-electron
bolometers each consisting of a small ($32 \times 14~\mathrm{\mu m}$) island of
degenerately doped silicon with superconducting aluminium contacts. Radiation
is coupled into the silicon absorber with a twin-slot antenna designed to
couple to 160-GHz radiation through a silicon lens.The first device has a
highly doped silicon absorber, the second has a highly doped strained-silicon
absorber.Using a novel method of cross-correlating the outputs from two
parallel amplifiers, we measure noise-equivalent powers of $3.0 \times
10^{-16}$ and $6.6 \times 10^{-17}~\mathrm{W\,Hz^{-1/2}}$ for the control and
strained device, respectively, when observing radiation from a 77-K source. In
the case of the strained device, the noise-equivalent power is limited by the
photon noise.


title:
A rational approximation of the arctangent function and a new approach
  in computing pi

abstract:
  We have shown recently that integration of the error function
${\rm{erf}}\left( x \right)$ represented in form of a sum of the Gaussian
functions provides an asymptotic expansion series for the constant pi. In this
work we derive a rational approximation of the arctangent function $\arctan
\left( x \right)$ that can be readily generalized it to its counterpart $ -
{\rm{sgn}}\left( x \right)\pi /2 + \arctan \left( x \right)$, where
${\rm{sgn}}\left( x \right)$ is the signum function. The application of the
expansion series for these two functions leads to a new asymptotic formula for
$\pi$.


title:
Dynamic rays of bounded-type transcendental self-maps of the punctured
  plane

abstract:
  We study the escaping set of functions in the class $\mathcal B^*$, that is,
holomorphic functions $f:\mathbb C^*\to\mathbb C^*$ for which both zero and
infinity are essential singularities, and the set of singular values of $f$ is
contained in a compact annulus of $\mathbb C^*$. For functions in the class
$\mathcal B^*$, escaping points lie in their Julia set. If $f$ is a composition
of finite order transcendental self-maps of $\mathbb C^*$ (and hence, in the
class $\mathcal B^*$), then we show that every escaping point of $f$ can be
connected to one of the essential singularities by a curve of points that
escape uniformly. Moreover, for every essential itinerary
$e\in\{0,\infty\}^\mathbb N$, we show that the escaping set of $f$ contains a
Cantor bouquet of curves that accumulate to $\{0,\infty\}$ according to $e$
under iteration by $f$.


title: The critical geometry of a thermal big bang

abstract:
  We explore the space of scalar-tensor theories containing two
non-conformalmetrics, and find a discontinuity pointing to a "critical"
cosmological solution. Due to the different maximal speeds of propagation for
matter and gravity,the cosmological fluctuations start off inside the horizon
even without inflation, and will more naturally have a thermal origin (since
there is never vacuum domination). The critical model makes an unambiguous,
non-tuned prediction for the spectral index of the scalar fluctuations: $n_S=
0.96478(64)$. Considering also that no gravitational waves are produced, we
have unveiled the most predictive model on offer. The model has a simple
geometrical interpretation as a probe 3-brane embedded in an $EAdS_2\times E_3$
geometry.


title:
Analysis and Design of Phase Desynchronization in Pulse-coupled
  Oscillators

abstract:
  By spreading phases on the unit circle, desynchronization algorithm is a
powerful tool to achieve round-robin scheduling, which is crucial in
applications as diverse as media access control of communication networks,
realization of analog-to-digital converters, and scheduling of traffic flows in
intersections. Driven by the increased application of pulse-coupled oscillators
in achieving synchronization, desynchronization of pulse-coupled oscillators is
also receiving more attention. In this paper, we propose a phase
desynchronization algorithm by rigorously analyzing the dynamics of
pulse-coupled oscillators and carefully designing the pulse based interaction
function. A systematic proof for convergence to phase desynchronization is also
given. Different from many existing results which can only achieve equal
separation of firing time instants, the proposed approach can achieve equal
separation of phases, which is more difficult to achieve due to phase jumps in
pulse-coupled oscillators. Furthermore, the new strategy can guarantee
achievement of desynchronization even when some nodes have identical initial
phases, a situation which fails most existing desynchronization approaches.
Numerical simulation results are provided to illustrate the effectiveness of
the theoretical results.


title:
Zero Distribution of Hermite-Pad\'e Polynomials and Convergence
  Properties of Hermite Approximants for Multivalued Analytic Functions

abstract:
  In the paper, we propose two new conjectures about the convergence of Hermite
Approximants of multivalued analytic functions of Laguerre class ${\mathscr
L}$. The conjectures are based in part on the numerical experiments, made
recently by the authors in [26] and [27].


title: Most Compact Parsimonious Trees

abstract:
  Construction of phylogenetic trees has traditionally focused on binary trees
where all species appear on leaves, a problem for which numerous efficient
solutions have been developed. Certain application domains though, such as
viral evolution and transmission, paleontology, linguistics, and phylogenetic
stemmatics, often require phylogeny inference that involves placing input
species on ancestral tree nodes (live phylogeny), and polytomies. These
requirements, despite their prevalence, lead to computationally harder
algorithmic solutions and have been sparsely examined in the literature to
date. In this article we prove some unique properties of most parsimonious live
phylogenetic trees with polytomies, and describe novel algorithms to find the
such trees without resorting to exhaustive enumeration of all possible tree
topologies.


title:
Comparing Approaches to Treatment Effect Estimation for Subgroups in
  Clinical Trials

abstract:
  Identifying subgroups, which respond differently to a treatment, both in
terms of efficacy and safety, is an important part of drug development. A
well-known challenge in exploratory subgroup analyses is the small sample size
in the considered subgroups, which is usually too low to allow for definite
comparisons. In early phase trials this problem is further exaggerated, because
limited or no clinical prior information on the drug and plausible subgroups is
available. We evaluate novel strategies for treatment effect estimation in
these settings in a simulation study motivated by real clinical trial
situations. We compare several approaches to estimate treatment effects for
selected subgroups, employing model averaging, resampling and Lasso regression
methods. Two subgroup identification approaches are employed, one based on
categorization of covariates and the other based on splines. Our results show
that naive estimation of the treatment effect, which ignores that a selection
has taken place, leads to bias and overoptimistic conclusions. For the
considered simulation scenarios virtually all evaluated novel methods provide
more adequate estimates of the treatment effect for selected subgroups, in
terms of bias, MSE and confidence interval coverage.


title: Hilbert transforms along Lipschitz direction fields: A lacunary model

abstract:
  We prove bounds for the truncated directional Hilbert transform in
$L^p(\mathbb{R}^2)$ for any $1<p<\infty$ under a combination of a Lipschitz
assumption and a lacunarity assumption. It is known that a lacunarity
assumption alone is not sufficient to yield boundedness for $p=2$, and it is a
major question in the field whether a Lipschitz assumption alone suffices, at
least for some $p$.


title: Insights into Quasar UV Spectra Using Unsupervised Clustering Analysis

abstract:
  Machine learning can provide powerful tools to detect patterns in
multi-dimensional parameter space. We use K-means -a simple yet powerful
unsupervised clustering algorithm which picks out structure in unlabeled data-
to study a sample of quasar UV spectra from the Quasar Catalog of the 10th Data
Release of the Sloan Digital Sky Survey of Paris et al. (2014). Detecting
patterns in large datasets helps us gain insights into the physical conditions
and processes giving rise to the observed properties of quasars. We use K-means
to find clusters in the parameter space of the equivalent width (EW), the blue-
and red-half-width at half-maximum (HWHM) of the Mg II 2800 A line, the C IV
1549 A line, and the C III] 1908 A blend in samples of Broad Absorption-Line
(BAL) and non-BAL quasars at redshift 1.6-2.1. Using this method, we
successfully recover correlations well-known in the UV regime such as the
anti-correlation between the EW and blueshift of the C IV emission line and the
shape of the ionizing Spectra Energy distribution (SED) probed by the strength
of He II and the Si III]/C III] ratio. We find this to be particularly evident
when the properties of C III] are used to find the clusters, while those of Mg
II proved to be less strongly correlated with the properties of the other lines
in the spectra such as the width of C IV or the Si III]/C III] ratio. We
conclude that unsupervised clustering methods (such as K-means) are powerful
methods for finding "natural" binning boundaries in multidimensional datasets
and discuss caveats and future work.


title: Unparticle contribution to the hydrogen atom ground state energy

abstract:
  In the present work we study the effect of unparticle modified static
potentials on the energy levels of the hydrogen atom. By using
Rayleigh-Schr\"odinger perturbation theory, we obtain the energy shift of the
ground state and we compare it with experimental data. Bounds on the unparticle
energy scale $\Lambda_\mathcal{U}$ as a function of the scaling dimension
$d_\mathcal{U}$ and the coupling constant $\lambda$ are derived. We show that
there exists a parameter region where bounds on $\Lambda_\mathcal{U}$ are
stringent, signalling that unparticles could be tested in atomic physics
experiments.


title: ALICE overview

abstract:
  Recent results from the ALICE experiment are presented with a particular
emphasis on particle identification, the nuclear modification factor ($R_{AA}$)
and azimuthal anisotropy ($v_2$). Comparison of lead-lead and proton-lead
results reveals evidence of collectivity in small systems.


title: The Corolla Polynomial for spontaneously broken Gauge Theories

abstract:
  In [1, 2, 3] the Corolla Polynomial $ \mathcal C (\Gamma) \in \mathbb C
[a_{h_1}, \ldots, a_{h_{\left \vert \Gamma^{[1/2]} \right \vert}}] $ was
introduced as a graph polynomial in half-edge variables $ \left \{ a_h \right
\} _{h \in \Gamma^{[1/2]}} $ over a 3-regular scalar quantum field theory (QFT)
Feynman graph $ \Gamma $. It allows for a covariant quantization of pure
Yang-Mills theory without the need for introducing ghost fields, clarifies the
relation between quantum gauge theory and scalar QFT with cubic interaction and
translates back the problem of renormalizing quantum gauge theory to the
problem of renormalizing scalar QFT with cubic interaction (which is super
renormalizable in 4 dimensions of spacetime). Furthermore, it is, as we
believe, useful for computer calculations. In [4] on which this paper is based
the formulation of [1, 2, 3] gets slightly altered in a fashion specialized in
the case of the Feynman gauge. It is then formulated as a graph polynomial $
\mathcal C ( \Gamma ) \in \mathbb C [a_{h_{1 \pm}}, \ldots, a_{h_{\left \vert
\Gamma^{[1/2]} \right \vert} \vphantom{h}_\pm}, b_{h_1}, \ldots, b_{h_{\left
\vert \Gamma^{[1/2]} \right \vert}}] $ in three different types of half-edge
variables $ \left \{ a_{h_+} , a_{h_-} , b_h \right \} _{h \in \Gamma^{[1/2]}}
$. This formulation is also suitable for the generalization to the case of
spontaneously broken gauge theories (in particular all bosons from the Standard
Model), as was first worked out in [4] and gets reviewed here.


title: X(5568) as a $s u \bar d \bar b$ tetraquark in a simple quark model

abstract:
  The $S$-wave eigenstates of tetraquarks of type $s u \bar d \bar b$ with
J$^{P}$ = 0$^{+}$, 1$^{+}$ and 2$^{+}$ are studied within a simple quark model
with chromomagnetic interaction and effective quark masses extracted from meson
and baryon spectra. It is tempting to see if this spectrum can accommodate the
new narrow structure X(5568), observed by the D\O~~Collaboration, but not
confirmed by the LHCb Collaboration. If it exists, such a tetraquark is a
system with four different flavors and its study can improve our understanding
of multiquark systems. The presently calculated mass of X(5568) agrees quite
well with the experimental value of he D\O~~Collaboration. Predictions are made
for the spectrum of the charmed partner $s u \bar d \bar c$. However we are
aware of the difficulty of extracting effective quark masses, from mesons and
baryons, to be used in multiquark systems.


title:
Hydrolytic degradation of ROMP thermosetting materials catalysed by
  bio-derived acids and enzyme: from network to linear materials

abstract:
  This paper reports the first example of the degradable ROMP thermosetting
materials catalysed by bio-derived acids and cutinase from Thermobifida
cellulosilytica (Thc_Cut1). The ROMP thermosetting materials are based on
norbornene dicarboximides containing acetal ester groups only in the crosslink
moiety. The insoluble cross-linked materials were subjected to acid-catalysed
hydrolysis using bio-derived acetic and citric acids as well as enzymatic
degradation using Thc_Cut1, resulting in the materials becoming completely
soluble in dichloromethane. 1H NMR and rheological analysis performed on
materials after acid-catalysed hydrolysis showed characteristics
indistinguishable to that of the linear polymer analogues. These analyses
confirmed the cleavage of the crosslink moiety upon degradation with the main
backbone chains remaining intact. The glass transition temperatures of the
polymer materials after acid-catalysed hydrolysis were the same of those
observed for the linear polymer analogue. TGA showed that the cross-linked
polymers thermally stable to 150 {\deg}C, beyond which showed weight losses due
to the thermal cleavage of the acetal ester linkages.


title: Torsion-free rank one sheaves over del Pezzo orders

abstract:
  Let A be a del Pezzo order on the projective plane over the field of complex
numbers. We prove that every torsion-free A-module of rank one can be deformed
into a locally free A-module of rank one.


title: Global smooth solutions for the inviscid SQG equation

abstract:
  In this paper, we show the existence of the first non trivial family of
classical global solutions of the inviscid surface quasi-geostrophic equation.


title:
Ferromagnetism and particle collisions: applications to protoplanetary
  disks and the meteoritical record

abstract:
  The meteoritical record shows both iron partitioning and tungsten isotopic
partitioning between matrix and chondrules. Tungsten is not abundant enough to
have driven its own isotopic partitioning, but if tungsten were correlated with
iron, then ferromagnetic interactions grains could help explain both
observations. We derive a practical parameterization for the increase in
particle-particle collision rates caused by mutually attracting particle
magnetic dipole moments. While the appropriate magnetic parameters remain
uncertain, we show that ambient magnetic fields in protoplanetary disks are
expected to be strong enough to magnetize iron metal bearing dust grains
sufficiently to drive large increases in their collision rates. Such increased
collision rates between iron metal rich grains could help preserve primordial
iron and W isotopic inhomogeneities; and would help explain why the
meteoritical record shows their partitioning in the solar nebula. The
importance of magnetic interactions for larger grains whose growth is balanced
by fragmentation is less clear, and will require future laboratory or numerical
studies.


title:
Density modulation-induced absolute laser-plasma-instabilities:
  simulations and theory

abstract:
  Fluid simulations show that when a sinusoidal density modulation is
superimposed on a linear density profile, convective instabilities can become
absolutely unstable. This conversion can occur for two-plasmon-decay and
stimulated Raman Scattering instabilities under realistic direct-drive inertial
confinement fusion conditions and can affect hot electron generation and laser
energy deposition. Analysis of the three-wave model shows that a sufficiently
large change of the density gradient in a linear density profile can turn
convective instabilities into absolute ones. An analytical expression is given
for the threshold of the gradient change, which depends on the convective gain
only.


title:
The effect of baryons on redshift space distortions and cosmic density
  and velocity fields in the EAGLE simulation

abstract:
  We use the EAGLE galaxy formation simulation to study the effects of baryons
on the power spectrum of the total matter and dark matter distributions and on
the velocity fields of dark matter and galaxies. On scales
$k{\stackrel{>}{{}_\sim}} 4{h\,{\rm Mpc}^{-1}}$ the effect of baryons on the
amplitude of the total matter power spectrum is greater than $1\%$. The
back-reaction of baryons affects the density field of the dark matter at the
level of $\sim3\%$ on scales of $1\leq k/({h\,{\rm Mpc}^{-1}})\leq 5$. The dark
matter velocity divergence power spectrum at
$k{\stackrel{<}{{}_\sim}}0.5{h\,{\rm Mpc}^{-1}}$ is changed by less than $1\%$.
The 2D redshift-space power spectrum is affected at the level of $\sim6\%$ at
$|\vec{k}|{\stackrel{>}{{}_\sim}} 1{h\,{\rm Mpc}^{-1}}$ (for $\mu>0.5$), but
for $|\vec{k}|\leq 0.4{h\,{\rm Mpc}^{-1}}$ it differs by less than $1\%$. We
report vanishingly small baryonic velocity bias for haloes: the peculiar
velocities of haloes with $M_{200}>3\times10^{11}{{\rm M}_{\odot}}$ (hosting
galaxies with $M_{*}>10^9{{\rm M}_{\odot}}$) are affected at the level of at
most $1~$km/s, which is negligible for $1\%$-precision cosmology. We caution
that since EAGLE overestimates cluster gas fractions it may also underestimate
the impact of baryons, particularly for the total matter power spectrum.
Nevertheless, our findings suggest that for theoretical modelling of redshift
space distortions and galaxy velocity-based statistics, baryons and their
back-reaction can be safely ignored at the current level of observational
accuracy. However, we confirm that the modelling of the total matter power
spectrum in weak lensing studies needs to include realistic galaxy formation
physics in order to achieve the accuracy required in the precision cosmology
era.


title:
Improved convergence rates for Lasserre-type hierarchies of upper bounds
  for box-constrained polynomial optimization

abstract:
  We consider the problem of minimizing a given $n$-variate polynomial $f$ over
the hypercube $[-1,1]^n$. An idea introduced by Lasserre, is to find a
probability distribution on $[-1,1]^n$ with polynomial density function $h$ (of
given degree $r$) that minimizes the expectation $\int_{[-1,1]^n}
f(x)h(x)d\mu(x)$, where $d\mu(x)$ is a fixed, finite Borel measure supported on
$[-1,1]^n$. It is known that, for the Lebesgue measure $d\mu(x) = dx$, one may
show an error bound $O(1/\sqrt{r})$ if $h$ is a sum-of-squares density, and an
$O(1/r)$ error bound if $h$ is the density of a beta distribution. In this
paper, we show an error bound of $O(1/r^2)$, if $d\mu(x) = \left(\prod_{i=1}^n
\sqrt{1-x_i^2} \right)^{-1}dx$ (the well-known measure in the study of
orthogonal polynomials), and $h$ has a Schm\"udgen-type representation with
respect to $[-1,1]^n$, which is a more general condition than a sum of squares.
The convergence rate analysis relies on the theory of polynomial kernels, and
in particular on Jackson kernels. We also show that the resulting upper bounds
may be computed as generalized eigenvalue problems, as is also the case for
sum-of-squares densities.


title: Filter Banks on Discrete Abelian Groups

abstract:
  In this work we provide polyphase, modulation, and frame theoretical analyses
of a filter bank on a discrete abelian group. Thus, multidimensional or cyclic
filter banks as well as filter banks for signals in $\ell^2(\mathbb{Z}^d\times
\mathbb{Z}_s)$ or $\ell^2(\mathbb{Z}_r \times \mathbb{Z}_s)$ spaces are studied
in a unified way. We obtain perfect reconstruction conditions and the
corresponding frame bounds.


title: Transient anomalous charge production in strong-field QCD

abstract:
  We investigate axial charge production in two-color QCD out of equilibrium.
We compute the real-time evolution starting with spatially homogeneous strong
gauge fields, while the fermions are in vacuum. The idealized class of initial
conditions is motivated by glasma flux tubes in the context of heavy-ion
collisions. We focus on axial charge production at early times, where important
aspects of the anomalous dynamics can be derived analytically. This is compared
to real-time lattice simulations. Quark production at early times leading to
anomalous charge generation is investigated using Wilson fermions. Our results
indicate that coherent gauge fields can transiently produce significant amounts
of axial charge density, while part of the induced charges persist to be
present even well beyond characteristic decoherence times. The comparisons to
analytic results provide stringent tests of real-time representations of the
axial anomaly on the lattice.


title:
Testing the effect of galactic feedback on the IGM at z ~ 6 with
  metal-line absorbers

abstract:
  We present models of low- and high-ionization metal-line absorbers (O I, C
II, C IV and Mg II) during the end of the reionization epoch, at z ~ 6. Using
four cosmological hydrodynamical simulations with different feedback schemes
(including the Illustris and Sherwood simulations) and two different choices of
hydro-solver, we investigate how the overall incidence rate and equivalent
width distribution of metal-line absorbers varies with the galactic wind
prescription. We find that the O I and C II absorbers are reasonably
insensitive to the feedback scheme. All models, however, struggle to reproduce
the observations of C IV and Mg II, which are probing down to lower
overdensities than O I and C II at z ~ 6, suggesting that the metals in the
simulations are not being transported out into the IGM efficiently enough. The
situation is improved but not resolved if we choose a harder (but still
reasonable) and/or (locally) increased UV background at z ~ 6.


title: A Dark Sector for $g_\mu-2$, $R_K$ and a Diphoton Resonance

abstract:
  We revisit a set of dark sector models, motivated by anomalies observed in
$B$ decays and the muon anomalous magnetic moment, in the light of a recently
reported diphoton excess around 750$\,$GeV. Interpreting the excess as a scalar
resonance associated with the symmetry breaking sector of a dark gauge group,
we show that a diphoton cross section of few fb can be accomodated, together
with anomalies in $R_K$ and $g_\mu-2$ within a minimal dark sector model. The
resulting prominent collider signatures are in the form of wide resonant
signals into top and muon pair final states below $\sim1\,$TeV. The model
further predicts a dark matter candidate, yet with a significantly
underabundant relic density, unless produced by an appropriate non-thermal
mechanism.


title: Observation of low frequency spin dynamics in INVAR Fe$_{65}$Ni$_{35}$

abstract:
  We present ferromagnetic neutron spin echo measurements and muon spin
relaxation ($\mu$SR) measurements of the spin dynamics in the ordered phase of
the metallic alloy INVAR Fe$_{65}$Ni$_{35}$. Both techniques display evidence
of slow spin dynamics in the ordered phase which could be associated with the
INVAR effect. Zero field (ZF) and longitudinal field $\mu$SR measurements
suggest the presence of two separate timescales of slow spin-dynamics in the
ordered phase; a fast component corresponding to that observed in our
neutron-spin-echo measurements and a second slow component which may be related
to the "cluster" spin-fluctuations or to the dynamics of disordered local
moments or both as suggested by previous neutron scattering measurements and
recent theoretical studies.


title: Concentration of total curvature of minimal surfaces in H^2xR

abstract:
  We prove a phenomenon of concentration of total curvature for stable minimal
surfaces in the product space H^2xR; where H^2 is the hyperbolic plane. Under
some geometric conditions on the asymptotic boundary of an oriented stable
minimal surface immersed in H^2xR, it has infinite total curvature. In
particular, we infer that a minimal graph M in H^2xR whose asymptotic boundary
is a graph over an arc of the asymptotic boundary of H^2, different from the
asymptotic boundary of the boundary of M, has infinite total curvature.
Consequently, if M is a stable minimal surface immersed into H^2xR with compact
boundary, such that its asymptotic boundary is a graph over the whole
asymptotic boundary of H^2; then it has infinite total curvature. We exhibit an
example of a minimal graph such that in a domain whose asymptotic boundary is a
vertical segment the total curvature is finite, but the total curvature of the
graph is infinite, by the theorem cited before. We also present some simple and
peculiar examples of infinite total curvature minimal surfaces in H^2xR and
their asymptotic boundaries.


title:
Scalable Linear Causal Inference for Irregularly Sampled Time Series
  with Long Range Dependencies

abstract:
  Linear causal analysis is central to a wide range of important application
spanning finance, the physical sciences, and engineering. Much of the existing
literature in linear causal analysis operates in the time domain.
Unfortunately, the direct application of time domain linear causal analysis to
many real-world time series presents three critical challenges: irregular
temporal sampling, long range dependencies, and scale. Moreover, real-world
data is often collected at irregular time intervals across vast arrays of
decentralized sensors and with long range dependencies which make naive time
domain correlation estimators spurious. In this paper we present a frequency
domain based estimation framework which naturally handles irregularly sampled
data and long range dependencies while enabled memory and communication
efficient distributed processing of time series data. By operating in the
frequency domain we eliminate the need to interpolate and help mitigate the
effects of long range dependencies. We implement and evaluate our new work-flow
in the distributed setting using Apache Spark and demonstrate on both Monte
Carlo simulations and high-frequency financial trading that we can accurately
recover causal structure at scale.


title:
Measuring logic complexity can guide pattern discovery in empirical
  systems

abstract:
  We explore a definition of complexity based on logic functions, which are
widely used as compact descriptions of rules in diverse fields of contemporary
science. Detailed numerical analysis shows that (i) logic complexity is
effective in discriminating between classes of functions commonly employed in
modelling contexts; (ii) it extends the notion of canalisation, used in the
study of genetic regulation, to a more general and detailed measure; (iii) it
is tightly linked to the resilience of a function's output to noise affecting
its inputs. We demonstrate its utility by measuring it in empirical data on
gene regulation, digital circuitry, and propositional calculus. Logic
complexity is exceptionally low in these systems. The asymmetry between "on"
and "off" states in the data correlates with the complexity in a non-null way;
a model of random Boolean networks clarifies this trend and indicates a common
hierarchical architecture in the three systems.

categories: physics.data-an cond-mat.stat-mech nlin.AO q-bio.MN


title: C-map for Born-Infeld theories

abstract:
  The c-map of four dimensional non-linear theories of electromagnetism is
considered both in the rigid case and in its coupling to gravity. In this way
theories with antisymmetric tensors and scalars are obtained, and the three
non-linear representations of N=2 supersymmetry partially broken to N=1
related. The manifest $\mathrm{Sp}(2n)$ and $\mathrm{U}(n)$ covariance of these
theories in their multifield extensions is also exhibited.


title:
Stability of fixed points and associated relative equilibria of the
  $3$-body problem on $\mathbb S^1$ and $\mathbb S^2$

abstract:
  We prove that the fixed points of the curved 3-body problem and their
associated relative equilibria are Lyapunov stable if the solutions are
restricted to $\mathbb S^1$, but unstable if the bodies are considered in
$\mathbb S^2$.


title: Thue's inequalities and the hypergeometric method

abstract:
  Following a method originally due to Siegel, we establish upper bounds for
the number of primitive integer solutions to inequalities of the shape $0<|F(x,
y)| \leq h$, where $F(x , y) =(\alpha x + \beta y)^r -(\gamma x + \delta y)^r
\in \mathbb{Z}[x ,y]$, $\alpha$, $\beta$, $\gamma$ and $\delta$ are algebraic
constants with $\alpha\delta-\beta\gamma \neq 0$, and $r \geq 3$ and $h$ are
integers. As an important application, we pay special attention to the binomial
Thue's inequaities $|ax^r - by^r| \leq c$. The proofs are based on the
hypergeometric method of Thue and Siegel and its refinement by Evertse.


title:
Semiclassical limit of the focusing NLS: Whitham equations and the
  Riemann-Hilbert Problem approach

abstract:
  The main goal of this paper is to put together: a) the Whitham theory
applicable to slowly modulated $N$-phase nonlinear wave solutions to the
focusing nonlinear Schr\"odinger (fNLS) equation, and b) the Riemann-Hilbert
Problem approach to particular solutions of the fNLS in the semiclassical
(small dispersion) limit that develop slowly modulated $N$-phase nonlinear wave
in the process of evolution. Both approaches have their own merits and
limitations. Understanding of the interrelations between them could prove
beneficial for a broad range of problems involving the semiclassical fNLS.


title: Central configurations of the curved $N$-body problem

abstract:
  We consider the $N$-body problem of celestial mechanics in spaces of nonzero
constant curvature. Using the concept of locked inertia tensor, we compute the
moment of inertia for systems moving on spheres and hyperbolic spheres and show
that we can recover the classical definition in the Euclidean case. After
proving some criteria for the existence of relative equilibria, we find a
natural way to define the concept of central configuration in curved spaces
using the moment of inertia, and show that our definition is formally similar
to the one that governs the classical problem. The existence criteria we
develop for central configurations help us provide several examples and prove
that, for any given point masses on spheres and hyperbolic spheres, central
configurations always exist. We end our paper with results concerning the
number of central configurations that lie on the same geodesic, thus extending
the celebrated theorem of Moulton to hyperbolic spheres and pointing out that
it has no straightforward generalization to spheres, where the count gets
complicated even in the case $N=2$.


title:
Hemodynamics of Stent Implantation Procedures in Coronary Bifurcations:
  an in vitro study

abstract:
  Stent implantation in coronary bifurcations presents unique challenges and
currently there is no universally accepted stent deployment approach. Despite
clinical and computational studies, to date, the effect of each stent
implantation method on the coronary artery hemodynamics is not well understood.
In this study the hemodynamics of stented coronary bifurcations under pulsatile
flow conditions were investigated experimentally. Three implantation methods,
provisional side branch (PSB), culotte (CUL), and crush (CRU), were
investigated using time-resolved particle image velocimetry (PIV) to measure
the velocity fields. Subsequently, hemodynamic parameters including wall shear
stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT)
were calculated and the pressure field through the vessel was non-invasively
quantified. The effects of each stented case were evaluated and compared
against an un-stented case. CRU provided the lowest compliance mismatch, but
demonstrated detrimental stent interactions. PSB, the clinically preferred
method, and CUL maintained many normal flow conditions. However, PSB provided
about a 300% increase in both OSI and RRT. CUL yielded a 10% and 85% increase
in OSI and RRT, respectively. The results of this study support the concept
that different bifurcation stenting techniques result in hemodynamic
environments that deviate from that of un-stented bifurcations, to varying
degrees.


title:
The reliability of observational measurements of column density
  probability distribution functions

abstract:
  Probability distribution functions (PDFs) of column densities are an
established tool to characterize the evolutionary state of interstellar clouds.
Using simulations, we show to what degree their determination is affected by
noise, line-of-sight contamination, field selection, and the incomplete
sampling in interferometric measurements. We solve the integrals that describe
the convolution of a cloud PDF with contaminating sources and study the impact
of missing information on the measured column density PDF. The effect of
observational noise can be easily estimated and corrected for if the root mean
square (rms) of the noise is known. For $\sigma_{noise}$ values below 40% of
the typical cloud column density, $N_{peak}$, this involves almost no
degradation of the accuracy of the PDF parameters. For higher noise levels and
narrow cloud PDFs the width of the PDF becomes increasingly uncertain. A
contamination by turbulent foreground or background clouds can be removed as a
constant shield if the PDF of the contamination peaks at a lower column or is
narrower than that of the observed cloud. Uncertainties in the definition of
the cloud boundaries mainly affect the low-column density part of the PDF and
the mean density. As long as more than 50% of a cloud are covered, the impact
on the PDF parameters is negligible. In contrast, the incomplete sampling of
the uv plane in interferometric observations leads to uncorrectable distortions
of the PDF of the produced maps. An extension of ALMA's capabilities would
allow us to recover the high-column density tail of the PDF but we found no way
to measure the intermediate and low column density part of the underlying cloud
PDF in interferometric observations.


title: Interrupted orbital motion in density-wave systems

abstract:
  In conventional metals, electronic transport in a magnetic field is
characterized by the motion of electrons along orbits on the Fermi surface,
which usually causes an increase in the resistivity through averaging over
velocities. Here we show that large deviations from this behavior can arise in
density-wave systems close to their ordering temperature. Specifically,
enhanced scattering off collective fluctuations can lead to a change of
direction of the orbital motion on reconstructed pockets. In weak magnetic
fields, this leads to linear magnetoconductivity, the sign of which depends on
the electric-field direction. At a critical magnetic field, the conductivity
crosses zero for certain directions, signifying a thermodynamic instability of
the density-wave state.


title:
Coupling volume-excluding compartment-based models of diffusion at
  different scales: Voronoi and pseudo-compartment approaches

abstract:
  Numerous processes across both the physical and biological sciences are
driven by diffusion. Partial differential equations (PDEs) are a popular tool
for modelling such phenomena deterministically, but it is often necessary to
use stochastic models to accurately capture the behaviour of a system,
especially when the number of diffusing particles is low. The stochastic models
we consider in this paper are `compartment-based': the domain is discretized
into compartments, and particles can jump between these compartments.
Volume-excluding effects (crowding) can be incorporated by blocking movement
with some probability.
  Recent work has established the connection between fine-grained models and
coarse-grained models incorporating volume exclusion, but only for uniform
lattices. In this paper we consider non-uniform, hybrid lattices that
incorporate both fine- and coarse-grained regions, and present two different
approaches to describing the interface of the regions. We test both techniques
in a range of scenarios to establish their accuracy, benchmarking against
fine-grained models, and show that the hybrid models developed in this paper
can be significantly faster to simulate than the fine-grained models in certain
situations, and are at least as fast otherwise.


title:
Encircling the dark: constraining dark energy via cosmic density in
  spheres

abstract:
  The recently published analytic probability density function for the mildly
non-linear cosmic density field within spherical cells is used to build a
simple but accurate maximum likelihood estimate for the redshift evolution of
the variance of the density, which, as expected, is shown to have smaller
relative error than the sample variance. This estimator provides a competitive
probe for the equation of state of dark energy, reaching a few percent accuracy
on wp and wa for a Euclid-like survey. The corresponding likelihood function
can take into account the configuration of the cells via their relative
separations. A code to compute one-cell density probability density functions
for arbitrary initial power spectrum, top-hat smoothing and various spherical
collapse dynamics is made available online so as to provide straightforward
means of testing the effect of alternative dark energy models and initial
power-spectra on the low-redshift matter distribution.


title:
Exploring University Students' Engagement with Online Video Lectures in
  a Blended Introductory Mechanics Course

abstract:
  The advent of MOOCs has stimulated interest in using online videos to deliver
content in university courses. We examined student engagement with 78 online
videos that we created and were incorporated into a one-semester blended
introductory mechanics course at the Georgia Institute of Technology. We found
that students were more engaged with videos that supported laboratory
activities than with videos that presented lecture content. In particular, the
percentage of students accessing laboratory videos was consistently greater
than 80 percent throughout the semester while the percentage of students
accessing lecture videos dropped to less than 40 percent by the end of the
term. Moreover, students were more likely to access the entirety of a
laboratory video than a lecture video. Our results suggest that students may
access videos based on perceived value: students appear to consider the
laboratory videos as essential for successfully completing the laboratories
while students appear to consider the lecture videos as something more akin to
supplementary material. We found there was little correlation between student
engagement with the videos and the performance in the course. In addition, an
examination of the in-video content suggests that students focus more on
concrete information that is explicitly required for assignment completion
(e.g., actions required to complete laboratory work, or formulas/mathematical
expressions needed to solve particular problems) and less on content that is
considered more conceptual in nature. The results of the study suggest ways in
which instructors may revise courses to better support student learning.


title: Personalized Persuasion for Social Interactions in Nursing Homes

abstract:
  This paper presents our preliminary investigation and approach towards a
mixed physical-virtual technology for stimulating social interactions among and
with older adults in nursing homes. We report on set of surveys, apps and focus
groups aiming at understanding the different motivations and obstacles in
promoting social interactions in institutionalised care. We then present our
approach to address some of the key themes found, e.g., the technological
disparity, lack of conversation topics and opportunities to interact


title:
Elliptic operators with unbounded diffusion coefficients perturbed by
  inverse square potentials in $L^p$-spaces

abstract:
  In this paper we give sufficient conditions on $\alpha \geq 0$ and $c\in
\mathbb{R}$ ensuring that the space of test functions
$C_c^\infty(\mathbb{R}^N)$ is a core for the operator $$L_0u=(1+|x|^\alpha
)\Delta u+\frac{c}{|x|^2}u=:Lu+\frac{c}{|x|^2}u,$$ and $L_0$ with suitable
domain generates a quasi-contractive and positivity preserving $C_0$-semigroup
in $L^p(\mathbb{R}^N),\,1<p<\infty$. The proofs are based on some
$L^p$-weighted Hardy's inequality and perturbation techniques.


title: Convex spaces, affine spaces, and commutants for algebraic theories

abstract:
  Certain axiomatic notions of $\textit{affine space}$ over a ring and
$\textit{convex space}$ over a preordered ring are examples of the notion of
$\mathcal{T}$-algebra for an algebraic theory $\mathcal{T}$ in the sense of
Lawvere. Herein we study the notion of $\textit{commutant}$ for Lawvere
theories that was defined by Wraith and generalizes the notion of
$\textit{centralizer clone}$. We focus on the Lawvere theory of $\textit{left
$R$-affine spaces}$ for a ring or rig $R$, proving that this theory can be
described as a commutant of the theory of pointed right $R$-modules. Further,
we show that for a wide class of rigs $R$ that includes all rings, these
theories are commutants of one another in the full finitary theory of $R$ in
the category of sets. We define $\textit{left $R$-convex spaces}$ for a
preordered ring $R$ as left affine spaces over the positive part $R_+$ of $R$.
We show that for any $\textit{firmly archimedean}$ preordered algebra $R$ over
the dyadic rationals, the theories of left $R$-convex spaces and pointed right
$R_+$-modules are commutants of one another within the full finitary theory of
$R_+$ in the category of sets. Applied to the ring of real numbers
$\mathbb{R}$, this result shows that the connection between convex spaces and
pointed $\mathbb{R}_+$-modules that is implicit in the integral representation
of probability measures is a perfect `duality' of algebraic theories.


title:
Numerical investigation of the Free Boundary regularity for a degenerate
  advection-diffusion problem

abstract:
  We study the free boundary regularity of the traveling wave solutions to a
degenerate advection-diffusion problem of Porous Medium type, whose existence
was proved in \cite{MonsaingonNovikovRoquejoffre}. We set up a finite
difference scheme allowing to compute approximate solutions and capture the
free boundaries, and we carry out a numerical investigation of their
regularity. Based on some nondegeneracy assumptions supported by solid
numerical evidence, we prove the Lipschitz regularity of the free boundaries.
Our simulations indicate that this regularity is optimal, and the free
boundaries seem to develop Lipschitz corners at least for some values of the
nonlinear diffusion exponent. We discuss analytically the existence of corners
in the framework of viscosity solutions to certain periodic Hamilton-Jacobi
equations, whose validity is again supported by numerical evidence.


title: IGR J17451-3022: a dipping and eclipsing low mass X-ray binary

abstract:
  In this paper, we report on the available X-ray data collected by INTEGRAL,
Swift, and XMM-Newton during the first outburst of the INTEGRAL transient IGR
J17451-3022, discovered in 2014 August. The monitoring observations provided by
the JEM-X instruments on-board INTEGRAL and the Swift/XRT showed that the event
lasted for about 9 months and that the emission of the source remained soft for
the entire period. The source emission is dominated by a thermal component
(kT~1.2 keV), most likely produced by an accretion disk. The XMM-Newton
observation carried out during the outburst revealed the presence of multiple
absorption features in the soft X-ray emission that could be associated to the
presence of an ionized absorber lying above the accretion disk, as observed in
many high-inclination low mass X-ray binaries. The XMM-Newton data also
revealed the presence of partial and rectangular X-ray eclipses (lasting about
820 s), together with dips. The latter can be associated with increases in the
overall absorption column density in the direction of the source. The detection
of two consecutive X-ray eclipses in the XMM-Newton data allowed us to estimate
the source orbital period at 22620.5(-1.8,+2.0) s (1{\sigma} c.l.).


title: Hard gap in a normal layer coupled to a superconductor

abstract:
  The ability to induce a sizable gap in the excitation spectrum of a normal
layer placed in contact with a conventional superconductor has become
increasingly important in recent years in the context of engineering a
topological superconductor. The quasiclassical theory of the proximity effect
shows that Andreev reflection at the superconductor/normal interface induces a
nonzero pairing amplitude in the metal but does not endow it with a gap.
Conversely, when the normal layer is atomically thin, the tunneling of Cooper
pairs induces an excitation gap that can be as large as the bulk gap of the
superconductor. We study how these two seemingly different views of the
proximity effect evolve into one another as the thickness of the normal layer
is changed. We show that a fully quantum-mechanical treatment of the problem
predicts that the induced gap is always finite but falls off with the thickness
of the normal layer, $d$. If $d$ is less than a certain crossover scale, which
is much larger than the Fermi wavelength, the induced gap is comparable to the
bulk gap. As a result, a sizable excitation gap can be induced in normal layers
that are much thicker than the Fermi wavelength.


title:
A thermodynamic paradigm for solution demixing inspired by nuclear
  transport in living cells

abstract:
  Living cells display a remarkable capacity to compartmentalize their
functional biochemistry. A particularly fascinating example is the cell
nucleus. Exchange of macromolecules between the nucleus and the surrounding
cytoplasm does not involve traversing a lipid bilayer membrane. Instead, large
protein channels known as nuclear pores cross the nuclear envelope and regulate
the passage of other proteins and RNA molecules. Beyond simply gating
diffusion, the system of nuclear pores and associated transport receptors is
able to generate substantial concentration gradients, at the energetic expense
of guanosine triphosphate (GTP) hydrolysis. In contrast to conventional
approaches to demixing such as reverse osmosis or dialysis, the biological
system operates continuously, without application of cyclic changes in pressure
or solvent exchange. Abstracting the biological paradigm, we examine this
transport system as a thermodynamic machine of solution demixing. Building on
the construct of free energy transduction and biochemical kinetics, we find
conditions for stable operation and optimization of the concentration gradients
as a function of dissipation in the form of entropy production.


title:
A discrete-ordinate discontinuous-streamline diffusion method for the
  radiative transfer equation

abstract:
  The radiative transfer equation (RTE) arises in many different areas of
science and engineering. In this paper, we propose and investigate a
discrete-ordinate discontinuous-streamline diffusion (DODSD) method for solving
the RTE, which is a combination of the discrete-ordinate technique and the
discontinuous-streamline diffusion method. Different from the discrete-ordinate
discontinuous Galerkin (DODG) method for the RTE, an artificial diffusion
parameter is added to the test functions in the spatial discretization.
Stability and error estimates in certain norms are proved. Numerical results
show that the proposed method can lead to a more accurate approximation in
comparison with the DODG method.


title: Cognitive Green Radio for Energy-Aware Communications

abstract:
  In 5G networks, the number of connected devices, data rate and data volume
per area, as well as the variety of QoS requirements, will attain unprecedented
scales. The achievement of these goals will rely on new technologies and
disruptive changes in network architecture and node design. Energy efficiency
is believed to play a key role in complementing the 5G technologies and
optimizing their deployment, dynamic configuration and management [1]. Within
the framework of green communications and networks, especially for
next-generation green cellular radio access networks, the GREAT (Green
Cognitive Radio for Energy-Aware wireless communication Technologies evolution)
initiative, a CominLabs Excellence Center (Laboratoire d'Excellence) and
Universit\'e Europ\'eenne de Bretagne (UEB)project, has mainly addressed the
fundamental issues of energy efficiency from various perspectives and angles,
leveraging on cognitive techniques, at networking level as well as at
thephysical layer level.


title:
Ordinal analysis of intuitionistic power and exponentiation Kripke
  Platek set theory

abstract:
  Until the 1970s, proof theoretic investigations were mainly concerned with
theories of inductive definitions, subsystems of analysis and finite type
systems. With the pioneering work of Gerhard Jaeger in the late 1970s and early
1980s, the focus switched to set theories, furnishing ordinal-theoretic proof
theory with a uniform and elegant framework. More recently it was shown that
these tools can even sometimes be adapted to the context of strong axioms such
as the powerset axiom, where one does not attain complete cut elimination but
can nevertheless extract witnessing information and characterize the strength
of the theory in terms of provable heights of the cumulative hierarchy. Here
this technology is applied to intuitionistic Kripke-Platek set theories IKP(P)
and IKP(E), where the operation of powerset and exponentiation, respectively,
is allowed as a primitive in the separation and collection schemata. In
particular, IKP(P) proves the powerset axiom whereas IKP(E) proves the
exponentiation axiom. The latter expresses that given any sets A and B, the
collection of all functions from A to B is a set, too. While IKP(P) can be
dealt with in a similar vein as its classical cousin, the treatment of IKP(E)
posed considerable obstacles. One of them was that in the infinitary system the
levels of terms become a moving target as they cannot be assigned a fixed level
in the formal cumulative hierarchy solely based on their syntactic structure.
As adumbrated in an earlier paper, the results of this paper are an important
tool in showing that several intuitionistic set theories with the collection
axiom possess the existence property, i.e., if they prove an existential
theorem then a witness can be provably described in the theory, one example
being intuitionistic Zermelo-Fraenkel set theory with bounded separation.


title: On the hierarchical risk-averse control problems for diffusion processes

abstract:
  In this paper, we consider a risk-averse control problem for diffusion
processes, in which there is a partition of the admissible control strategy
into two decision-making groups (namely, the {\it leader} and {\it follower})
with different cost functionals and risk-averse satisfactions. Our approach,
based on a hierarchical optimization framework, requires that a certain level
of risk-averse satisfaction be achieved for the {\it leader} as a priority over
that of the {\it follower's} risk-averseness. In particular, we formulate such
a risk-averse control problem involving a family of time-consistent dynamic
convex risk measures induced by conditional $g$-expectations (i.e.,
filtration-consistent nonlinear expectations associated with the generators of
certain backward stochastic differential equations). Moreover, under suitable
conditions, we establish the existence of optimal risk-averse solutions, in the
sense of viscosity solutions, for the corresponding risk-averse dynamic
programming equations. Finally, we briefly comment on the implication of our
results.


title:
The anisotropy induced by defects of "random local field" type in O(n)
  models and suppression of the Imry-Ma inhomogeneous state

abstract:
  We demonstrate that in the system with anisotropic distribution of the
defect-induced random local field directions in the n-dimensional space of
vector order parameter with the O(n) symmetry, the defect-induced effective
anisotropy arises for the space dimensionality 2<d<4. If the anisotropy
constant exceeds the threshold value, then an inhomogeneous state predicted by
Imry and Ma becomes energetically unfavorable, and the system goes back to the
state with the long-range order.


title: Products of Menger spaces: a combinatorial approach

abstract:
  We construct Menger subsets of the real line whose product is not Menger in
the plane. In contrast to earlier constructions, our approach is purely
combinatorial. The set theoretic hypothesis used in our construction is far
milder than earlier ones, and holds in all but the most exotic models of real
set theory. On the other hand, we establish productive properties for versions
of Menger's property parameterized by filters and semifilters. In particular,
the Continuum Hypothesis implies that every productively Menger set of real
numbers is productively Hurewicz, and each ultrafilter version of Menger's
property is strictly between Menger's and Hurewicz's classic properties. We
include a number of open problems emerging from this study.


title:
On bounded-type thin local sets of the two-dimensional Gaussian free
  field

abstract:
  We study certain classes of local sets of the two-dimensional Gaussian free
field (GFF) in a simply-connected domain, and their relation to the conformal
loop ensemble CLE(4) and its variants. More specifically, we consider
bounded-type thin local sets (BTLS), where thin means that the local set is
small in size, and bounded-type means that the harmonic function describing the
mean value of the field away from the local set is bounded by some
deterministic constant. We show that a local set is a BTLS if and only if it is
contained in some nested version of the CLE(4) carpet, and prove that all BTLS
are necessarily connected to the boundary of the domain. We also construct all
possible BTLS for which the corresponding harmonic function takes only two
prescribed values and show that all these sets (and this includes the case of
CLE(4)) are in fact measurable functions of the GFF.


title:
Thermal and electronic fluctuations of flexible adsorbed molecules:
  Azobenzene on Ag(111)

abstract:
  We investigate the thermal and electronic collective fluctuations that
contribute to the finite-temperature adsorption properties of flexible
adsorbates on surfaces on the example of the molecular switch azobenzene
C$_{12}$H$_{10}$N$_{2}$ on the Ag(111) surface. Using first-principles
molecular dynamics simulations we obtain the free energy of adsorption that
accurately accounts for entropic contributions, whereas the inclusion of
many-body dispersion interactions accounts for the electronic correlations that
govern the adsorbate binding. We find the adsorbate properties to be strongly
entropy-driven, as can be judged by a kinetic molecular desorption prefactor of
10$^{24}$ s$^{-1}$ that largely exceeds previously reported estimates. We
relate this effect to sizable fluctuations across structural and electronic
observables. Comparison of our calculations to temperature-programmed
desorption measurements demonstrates that finite-temperature effects play a
dominant role for flexible molecules in contact with polarizable surfaces, and
that recently developed first-principles methods offer an optimal tool to
reveal novel collective behavior in such complex systems.


title:
Channel Decorrelation For Stereo Acoustic Echo Cancellation In
  High-Quality Audio Communication

abstract:
  In this paper, we address an important problem in high-quality audio
communication systems. Acoustic echo cancellation with stereo signals is
generally an under-determined problem because of the generally important
correlation that exists between the left and right channels. In this paper, we
present a novel method of significantly reducing that correlation without
affecting the audio quality. This method is perceptually motivated and combines
a shaped comb-allpass (SCAL) filter with the injection of psychoacoustically
masked noise. We show that the proposed method performs significantly better
than other known methods for channel decorrelation.


title:
Variational Monte Carlo study of chiral spin liquid in quantum
  antiferromagnet on the triangular lattice

abstract:
  By using Gutzwiller projected fermionic wave functions and variational Monte
Carlo technique, we study the spin-$1/2$ Heisenberg model with the
first-neighbor ($J_1$), second-neighbor ($J_2$), and additional scalar chiral
interaction $J_{\chi}{\bf S}_i \cdot ({\bf S}_j \times {\bf S}_k)$ on the
triangular lattice. In the non-magnetic phase of the $J_1-J_2$ triangular model
with $0.08 \lesssim J_2/J_1 \lesssim 0.16$, recent density-matrix
renormalization group (DMRG) studies [Zhu and White, Phys. Rev. B {\bf 92},
041105 (2015); Hu, Gong, Zhu, and Sheng, Phys. Rev. B {\bf 92}, 140403 (2015)]
find a possible gapped spin liquid with the signal of a competition between a
chiral and a $Z_2$ spin liquid. Motivated by the DMRG results, we consider the
chiral interaction $J_{\chi}{\bf S}_i \cdot ({\bf S}_j \times {\bf S}_k)$ as a
pertubation for this non-magnetic phase. We find that with growing $J_{\chi}$,
the gapless U(1) Dirac spin liquid, which has the best variational energy for
$J_{\chi}=0$, exhibits the energy instability towards a gapped spin liquid with
non-trivial magnetic fluxes and nonzero chiral order. We calculate topological
Chern number and ground-state degeneracy, both of which identify this flux
state as the chiral spin liquid with fractionalized Chern number $C=1/2$ and
two-fold topological degeneracy. Our results indicate a positive direction to
stabilize a chiral spin liquid near the non-magnetic phase of the $J_1-J_2$
triangular model.


title:
A Second-Order Cone Based Approach for Solving the Trust Region
  Subproblem and Its Variants

abstract:
  We study the trust-region subproblem (TRS) of minimizing a nonconvex
quadratic function over the unit ball with additional conic constraints.
Despite having a nonconvex objective, it is known that the classical TRS and a
number of its variants are polynomial-time solvable. In this paper, we follow a
second-order cone (SOC) based approach to derive an exact convex reformulation
of the TRS under a structural condition on the conic constraint. Our structural
condition is immediately satisfied when there is no additional conic
constraints, and it generalizes several such conditions studied in the
literature. As a result, our study highlights an explicit connection between
the classical nonconvex TRS and smooth convex quadratic minimization, which
allows for the application of cheap iterative methods such as Nesterov's
accelerated gradient descent, to the TRS. Furthermore, under slightly stronger
conditions, we give a low-complexity characterization of the convex hull of the
epigraph of the nonconvex quadratic function intersected with the constraints
defining the domain without any additional variables. We also explore the
inclusion of additional hollow constraints to the domain of the TRS, and
convexification of the associated epigraph.


title:
High pressure magnetic state of MnP probed by means of muon-spin
  rotation

abstract:
  We report a detailed $\mu$SR study of the pressure evolution of the magnetic
order in the manganese based pnictide MnP, which has been recently found to
undergo a superconducting transition under pressure once the magnetic ground
state is suppressed. Using the muon as a volume sensitive local magnetic probe,
we identify a ferromagnetic state as well as two incommensurate helical states
(with propagation vectors ${\bf Q}$ aligned along the crystallographic $c-$ and
$b-$directions, respectively) which transform into each other through first
order phase transitions as a function of pressure and temperature. Our data
appear to support that the magnetic state from which superconductivity develops
at higher pressures is an incommensurate helical phase.


title: Quantum Zeno subspaces by repeated multi-spin projections

abstract:
  Repeated observations inhibit the coherent evolution of quantum states
through the quantum Zeno effect. In multi-qubit systems this effect provides
new opportunities to control complex quantum states. Here, we experimentally
demonstrate that repeatedly projecting joint observables of multiple spins
creates coherent quantum Zeno subspaces and simultaneously suppresses dephasing
caused by the environment. We encode up to two logical qubits in these
subspaces and show that the enhancement of the dephasing time with increasing
number of projections follows a scaling law that is independent of the number
of spins involved. These results provide new insights into the interplay
between frequent multi-spin measurements and non-Markovian noise and pave the
way for tailoring the dynamics of multi-qubit systems through repeated
projections.


title:
Summary Transfer: Exemplar-based Subset Selection for Video
  Summarization

abstract:
  Video summarization has unprecedented importance to help us digest, browse,
and search today's ever-growing video collections. We propose a novel subset
selection technique that leverages supervision in the form of human-created
summaries to perform automatic keyframe-based video summarization. The main
idea is to nonparametrically transfer summary structures from annotated videos
to unseen test videos. We show how to extend our method to exploit semantic
side information about the video's category/genre to guide the transfer process
by those training videos semantically consistent with the test input. We also
show how to generalize our method to subshot-based summarization, which not
only reduces computational costs but also provides more flexible ways of
defining visual similarity across subshots spanning several frames. We conduct
extensive evaluation on several benchmarks and demonstrate promising results,
outperforming existing methods in several settings.


title:
Mapping an Audience Centric World Wide Web: A Departure From Hyperlink
  Analysis

abstract:
  This paper argues that maps of the Web's structure based solely on technical
infrastructure such as hyperlinks may bear little resemblance to maps based on
Web usage, as cultural factors drive the latter to a larger extent. To test
this thesis, the study constructs two network maps of 1000 globally most
popular Web Domains, one based on hyperlinks and the other using an "audience
centric" approach with ties based on shared audience traffic between these
domains. Analyses of the two networks reveal that unlike the centralized
structure of the hyperlinks network with few dominant "core" websites, the
audience network is more decentralized and clustered to a larger extent along
geo-linguistic lines.


title:
Resolving the extended atmosphere and the inner wind of Mira ($o$ Ceti)
  with long ALMA baselines

abstract:
  The prototypical Mira variable, $o$ Cet (Mira), has been observed as a
Science Verification target in the 2014 ALMA Long Baseline Campaign with a
longest baseline of 15 km. ALMA clearly resolves the images of the continuum
and molecular line emission/absorption at an angular resolution of ~30 mas at
220 GHz. We image the data of the $^{28}$SiO v=0, 2 $J$=5-4 and H$_2$O
$\nu_2$=1 $J(K_a,K_c)$=5(5,0)-6(4,3) transitions and extract spectra from
various lines-of-sight towards Mira's extended atmosphere. In the course of
imaging, we encountered ambiguities in the resulting images and spectra that
appear to be related to the performance of the CLEAN algorithm. We resolve
Mira's millimetre continuum emission and our data are consistent with a radio
photosphere with a brightness temperature of 2611$\pm$51 K, in agreement with
recent results obtained with the VLA. We do not confirm the existence of a
compact region (<5 mas) of enhanced brightness. We derive the gas density,
kinetic temperature, molecular abundance and outflow/infall velocities in
Mira's extended atmosphere by modelling the SiO and H$_2$O lines. We find that
SiO-bearing gas starts to deplete beyond 4$R_\star$ and at a kinetic
temperature of $\lesssim$600 K. The inner dust shells are probably composed of
grain types other than pure silicates. During this observation, Mira's
atmosphere generally exhibited infall motion, with a shock front of velocity
$\lesssim$12 km/s outside the radio photosphere. The structures predicted by
the hydrodynamical model CODEX can reproduce the observed spectra in
astonishing detail; while some other models fail when confronted with the new
data. Combined with radiative transfer modelling, ALMA successfully
demonstrates the ability to reveal the physical conditions of the extended
atmospheres and inner winds of AGB stars in unprecedented detail. (Abbreviated
abstract)


title: Output Regulation for Systems on Matrix Lie-group

abstract:
  This paper deals with the problem of output regulation for systems defined on
matrix Lie-Groups. Reference trajectories to be tracked are supposed to be
generated by an exosystem, defined on the same Lie-Group of the controlled
system, and only partial relative error measurements are supposed to be
available. These measurements are assumed to be invariant and associated to a
group action on a homogeneous space of the state space. In the spirit of the
internal model principle the proposed control structure embeds a copy of the
exosystem kinematic. This control problem is motivated by many real
applications fields in aerospace, robotics, projective geometry, to name a few,
in which systems are defined on matrix Lie-groups and references in the
associated homogenous spaces.


title: Self-gravitating charged fluid spheres with anisotropic pressures

abstract:
  The coupled system of the spherically symmetric Einstein--Maxwell
differential equations is solved under two different source conditions:
non-zero electric charge and pressure anisotropy. Expressions for the metric
functions, and pressures which extend the Tolman VII exact solution are deduced
from the new solutions. By applying boundary conditions to these solutions, all
integration constants are computed in terms of parameters that are physically
meaningful.


title: Remarks on Barr's theorem: Proofs in geometric theories

abstract:
  A theorem, usually attributed to Barr, yields that (A) geometric implications
deduced in classical L_{\infty\omega} logic from geometric theories also have
intuitionistic proofs. Barr's theorem is of a topos-theoretic nature and its
proof is non-constructive. In the literature one also finds mysterious comments
about the capacity of this theorem to remove the axiom of choice from
derivations. This article investigates the proof-theoretic side of Barr's
theorem and also aims to shed some light on the axiom of choice part. More
concretely, a constructive proof of the Hauptsatz for L_{\infty\omega} is given
and is put to use to arrive at a simple proof of (A) that is formalizable in
constructive set theory and Martin-Loef type theory.


title:
Beyond Triplet: Unconventional Superconductivity in a Spin-3/2
  Topological Semimetal

abstract:
  In all known fermionic superfluids, Cooper pairs are composed of spin-1/2
quasi-particles that pair to form either spin-singlet or spin-triplet bound
states. The "spin" of a Bloch electron, however, is fixed by the symmetries of
the crystal and the atomic orbitals from which it is derived, and in some cases
can behave as if it were a spin-3/2 particle. The superconducting state of such
a system allows pairing beyond spin-triplet, with higher spin quasi-particles
combining to form quintet or septet pairs. Here, we report evidence of
unconventional superconductivity emerging from a spin-3/2 quasiparticle
electronic structure in the half-Heusler semimetal YPtBi, a low-carrier density
noncentrosymmetric cubic material with a high symmetry that preserves the
$p$-like $j=3/2$ manifold in the Bi-based $\Gamma_8$ band in the presence of
strong spin-orbit coupling. With a striking linear temperature dependence of
the London penetration depth, the existence of line nodes in the
superconducting order parameter $\Delta$ is directly explained by a
mixed-parity Cooper pairing model with high total angular momentum, consistent
with a high-spin fermionic superfluid state. We propose a $\mathbf{k\cdot p}$
model of the $j=3/2$ fermions to explain how a dominant $J$=3 septet pairing
state is the simplest solution that naturally produces nodes in the mixed
even-odd parity gap. Together with the underlying topologically non-trivial
band structure, the unconventional pairing in this system represents a truly
novel form of superfluidity that has strong potential for leading the
development of a new generation of topological superconductors.


title: Pairing of j=3/2 fermions in half-Heusler superconductors

abstract:
  We theoretically consider the superconductivity of the topological
half-Heusler semimetals YPtBi and LuPtBi. We show that pairing occurs between
j=3/2 fermion states, which leads to qualitative differences from the
conventional theory of pairing between j=1/2 states. In particular, this
permits Cooper pairs with quintet or septet total angular momentum, in addition
to the usual singlet and triplet states. Purely on-site interactions can
generate s-wave quintet time-reversal symmetry-breaking states with
topologically nontrivial point or line nodes. These local s-wave quintet pairs
reveal themselves as d-wave states in momentum space. Furthermore, due to the
broken inversion symmetry in these materials, the s-wave singlet state can mix
with a p-wave septet state, again with topologically-stable line nodes. Our
analysis lays the foundation for understanding the unconventional
superconductivity of the half-Heuslers.


title:
Proposal for a bulk material based on a monolayer FeSe on SrTiO3
  high-temperature superconductor

abstract:
  Motivated by the high superconducting transition temperature of monolayer
FeSe on SrTiO3, we propose a potential three-dimensional high-temperature
superconductor superlattice FeSe-SrTiO3 and study its structural stability and
electronic structure using density functional theory. We find that the binding
energy between the FeSe and SrTiO3 layers is about 0.7 eV per (Fe2Se2) unit and
that it saturates already within a single TiO2 atomic layer of SrTiO3. In
addition we analyzed the dynamical stability of the superlattice and compared
it to the case of bulk SrTiO3.


title:
The influence of a weak magnetic field in the Renormalization-Group
  functions of (2+1)-dimensional Dirac systems

abstract:
  The experimental observation of the renormalization of the Fermi velocity
$v_{F}$ as a function of doping has been a landmark for confirming the
importance of electronic interactions in graphene. Although the experiments
were performed in the presence of a perpendicular magnetic field $B$, the
measurements are well described by a renormalization-group (RG) theory that did
not include it. Here we clarify this issue, for both massive and massless Dirac
systems, and show that for the weak magnetic fields at which the experiments
are performed, there is no change in the renormalization-group functions. Our
calculations are carried out in the framework of the Pseudo-quantum
electrodynamics (PQED) formalism, which accounts for dynamical interactions. We
include only the linear dependence in $B$, and solve the problem using two
different parametrizations, the Feynman and the Schwinger one. We confirm the
results obtained earlier within the RG procedure and show that, within linear
order in the magnetic field, the only contribution to the renormalization of
the Fermi velocity arises due to interactions. In addition, for gapped systems,
we observe a running of the mass parameter.


title:
Radiation reaction on a Brownian scalar electron in high-intensity
  fields

abstract:
  Radiation reaction against a relativistic electron is of critical importance
since the experiment to check this "quantumness" becomes possible soon with an
extremely high-intensity laser beam. However, there is a fundamental
mathematical quest to apply any laser profiles to laser focusing and
superposition beyond the Furry picture of its usual method by a plane wave. To
give the apparent meaning of $q(\chi)$ the quantumness factor with respect to a
radiation process is absent. Thus for resolving the above questions, we propose
stochastic quantization of the classical radiation reaction model for any laser
field profiles, via the construction of the relativistic Brownian kinematics
with the dynamics of a scalar electron and the Maxwell equation with a current
by a Brownian quanta. This is the first proposal of the coupling system between
a relativistic Brownian quanta and fields in Nelson's stochastic quantization.
Therefore, we can derive the radiation field by its Maxwell equation, too. This
provides us the fact that $q(\chi)$ produced by QED is regarded as
$\mathscr{P}(\varOmega_{\tau}^{\mathrm{ave}})$ of an existence probability such
that a scalar electron stay on its average trajectory.


title: The Dynamics of the Schrodinger-Newton System with Self-Field Coupling

abstract:
  We probe the dynamics of a modified form of the Schrodinger-Newton system of
gravity coupled to single particle quantum mechanics. At the masses of interest
here, the ones associated with the onset of "collapse" (where the gravitational
attraction is competitive with the quantum mechanical dissipation), we show
that the Schrodinger ground state energies match the Dirac ones with an error
of ~ 10%. At the Planck mass scale, we predict the critical mass at which a
potential collapse could occur for the self-coupled gravitational case, m ~ 3.3
Planck mass, and show that gravitational attraction opposes Gaussian spreading
at around this value, which is a factor of two higher than the one predicted
(and verified) for the Schrodinger-Newton system. Unlike the Schrodinger-Newton
dynamics, we do not find that the self-coupled case tends to decay towards its
ground state; there is no collapse in this case.


title: Temporally coherent 4D reconstruction of complex dynamic scenes

abstract:
  This paper presents an approach for reconstruction of 4D temporally coherent
models of complex dynamic scenes. No prior knowledge is required of scene
structure or camera calibration allowing reconstruction from multiple moving
cameras. Sparse-to-dense temporal correspondence is integrated with joint
multi-view segmentation and reconstruction to obtain a complete 4D
representation of static and dynamic objects. Temporal coherence is exploited
to overcome visual ambiguities resulting in improved reconstruction of complex
scenes. Robust joint segmentation and reconstruction of dynamic objects is
achieved by introducing a geodesic star convexity constraint. Comparative
evaluation is performed on a variety of unstructured indoor and outdoor dynamic
scenes with hand-held cameras and multiple people. This demonstrates
reconstruction of complete temporally coherent 4D scene models with improved
nonrigid object segmentation and shape reconstruction.


title: Holographic Fermi Liquids in a Spontaneously Generated Lattice

abstract:
  We discuss fermions in a spontaneously generated holographic lattice
background. The lattice structure at the boundary is generated by introducing a
higher-derivative interaction term between a U(1) gauge field and a scalar
field. We solve the equations of motion below the critical temperature at which
the lattice forms, and analyze the change in the Fermi surface due to the
lattice. The fermion band structure is found to exhibit a band gap due to
lattice effects.


title: Spitzer IRAC Sparsely Sampled Phase Curve of the Exoplanet WASP-14b

abstract:
  Motivated by a high Spitzer IRAC oversubscription rate, we present a new
technique of randomly and sparsely sampling phase curves of hot Jupiters.
Snapshot phase curves are enabled by technical advances in precision pointing
as well as careful characterization of a portion of the central pixel on the
array. This method allows for observations which are a factor of roughly two
more efficient than full phase curve observations, and are furthermore easier
to insert into the Spitzer observing schedule. We present our pilot study from
this program using the exoplanet WASP-14b. Data of this system were taken both
as a sparsely sampled phase curve as well as a staring mode phase curve. Both
datasets as well as snapshot style observations of a calibration star are used
to validate this technique. By fitting our WASP-14b phase snapshot dataset, we
successfully recover physical parameters for the transit and eclipse depths as
well as amplitude and maximum and minimum of the phase curve shape of this
slightly eccentric hot Jupiter. We place a limit on the potential phase to
phase variation of these parameters since our data are taken over many phases
over the course of a year. We see no evidence for eclipse depth variations
compared to other published WASP-14b eclipse depths over a 3.5 year baseline.