title: Suppression of spatially periodic patterns by dc voltage

abstract:
  The effect of superposed dc and ac applied voltages on two types of spatially
periodic instabilities in nematic liquid crystals, flexoelectric domains (FD)
and electroconvection (EC), was studied. The onset characteristics, threshold
voltages and critical wave vectors, were determined. We found that in general
the superposition of driving with different time symmetries inhibits the
pattern forming mechanisms for FD and EC as well. As a consequence the onset
extends to much higher voltages than the individual dc or ac thresholds. A dc
bias induced reduction of the crossover frequency from the conductive to the
dielectric EC regimes and a peculiar transition between two types of
flexodomains with different wavelengths were detected. Direct measurements of
the change of the electrical conductivity and its anisotropy, induced by the
applied dc voltage component, showed that the dc bias substantially affects
both parameters. Taking into account the experimentally detected variations of
the conductivity in the linear stability analysis of the underlying
nemato-hydrodynamic equations, a qualitative agreement with the experimental
findings on the onset behavior of spatially periodic instabilities was
obtained.


title: Quantifying Spontaneously Symmetry Breaking of Quantum Many-body Systems

abstract:
  Spontaneous symmetry breaking is related to the appearance of emergent
phenomena, while a non-vanishing order parameter has been viewed as the sign of
turning into such symmetry breaking phase. Recently, we have proposed a
continuous measure of symmetry of a physical system using group theoretical
approach. Within this framework, we study the spontaneous symmetry breaking in
the conventional superconductor and Bose-Einstein condensation by showing both
the two many body systems can be mapped into the many spin model. Moreover we
also formulate the underlying relation between the spontaneous symmetry
breaking and the order parameter quantitatively. The degree of symmetry stays
unity in the absence of the two emergent phenomena, while decreases
exponentially at the appearance of the order parameter which indicates the
inextricable relation between the spontaneous symmetry and the order parameter.


title: Regenerative Soot-II: Emission of carbon clusters from sooting plasma

abstract:
  A hollow cathode source with a specially designed cusp magnetic field B whose
z component is a function of radius and the azimuth angle, provides clustering
environment to the sputtered carbon atoms and ions. The distinctive features of
the source are its sooting properties that depend upon the two well-defined
regions within the discharge. The cusp field drives both of these regions but
in different modes. One region ionizes the source gas, introduces the sputtered
carbon from the graphite hollow cathode while the other is the collision
dominated gyration motion of the positive carbon ions along the z component of
the magnetic field contours. Tunability of plasma discharge characteristics
provides the tool to investigate clustering in the sooting plasma


title:
Carrier induced ferromagnetism in the insulating Mn doped III-V
  semiconductor InP

abstract:
  Although InP and GaAs have very similar band-structure their magnetic
properties appear to drastically differ. Critical temperatures in (In,Mn)P are
much smaller than that of (Ga,Mn)As and scale linearly with Mn concentration.
This is in contrast to the square root behaviour found in (Ga,Mn)As. Moreover
the magnetization curve exhibits an unconventional shape in (In,Mn)P
contrasting with the conventional one of well annealed (Ga,Mn)As. By combining
several theoretical approaches, the nature of ferromagnetism in Mn doped InP is
investigated. It appears that the magnetic properties are essentially
controlled by the position of the Mn acceptor level. Our calculations are in
excellent agreement with recent measurements for both critical temperatures and
magnetizations. The results are only consistent with a Fermi level lying in an
impurity band, ruling out the possibility to understand the physical properties
of Mn doped InP within the valence band scenario. The quantitative success
found here reveals a predictive tool of choice that should open interesting
pathways to address magnetic properties in other compounds


title: Stochastic Heavy Ball

abstract:
  This paper deals with a natural stochastic optimization procedure derived
from the so-called Heavy-ball method differential equation, which was
introduced by Polyak in the 1960s with his seminal contribution [Pol64]. The
Heavy-ball method is a second-order dynamics that was investigated to minimize
convex functions f . The family of second-order methods recently received a
large amount of attention, until the famous contribution of Nesterov [Nes83],
leading to the explosion of large-scale optimization problems. This work
provides an in-depth description of the stochastic heavy-ball method, which is
an adaptation of the deterministic one when only unbiased evalutions of the
gradient are available and used throughout the iterations of the algorithm. We
first describe some almost sure convergence results in the case of general
non-convex coercive functions f . We then examine the situation of convex and
strongly convex potentials and derive some non-asymptotic results about the
stochastic heavy-ball method. We end our study with limit theorems on several
rescaled algorithms.


title:
Regenerative Soot-III: Role of the kinetic and potential sputtering in
  the regeneration of the soot

abstract:
  We have used the photoemission spectroscopy of the graphite hollow cathode
sooting discharge to identify the roles played by the kinetic and potential
sputtering, respectively. Our indicators are the relative densities of the
sputtered carbon C, the Ne metastable atoms, and the ionized components (Ne+)
of the regenerative sooting plasma. We find that the metastable atoms are the
main agents for the regeneration of the soot.


title: On the cells in a stationary Poisson hyperplane mosaic

abstract:
  Let $X$ be the mosaic generated by a stationary Poisson hyperplane process
$\hat X$ in ${\mathbb R}^d$. Under some mild conditions on the spherical
directional distribution of $\hat X$ (which are satisfied, for example, if the
process is isotropic), we show that with probability one the set of cells
($d$-polytopes) of $X$ has the following properties. The translates of the
cells are dense in the space of convex bodies. Every combinatorial type of
simple $d$-polytopes is realized infinitely often by the cells of $X$. A
further result concerns the distribution of the typical cell.


title:
A Further Study of an $L^2$-norm Based Test for the Equality of Several
  Covariance Functions

abstract:
  For the multi-sample equal covariance function (ECF) testing problem, Zhang
(2013) proposed an $L^{2}$-norm based test. However, its asymptotic power and
finite sample performance have not been studied. In this paper, its asymptotic
power is investigated under some mild conditions. It is shown that the
$L^2$-norm based test is root-$n$ consistent. In addition, intensive simulation
studies demonstrate that in terms of size-controlling and power, the
$L^{2}$-norm based test outperforms the dimension-reduction based test proposed
by Fremdt et al. (2013) when the functional data are less correlated or when
the effective signal information is located in high frequencies. Two real data
applications are also presented to demonstrate the good performance of the
$L^2$-norm based test.


title:
A Supremum-Norm Based Test for the Equality of Several Covariance
  Functions

abstract:
  In this paper, we propose a new test for the equality of several covariance
functions for functional data. Its test statistic is taken as the supremum
value of the sum of the squared differences between the estimated individual
covariance functions and the pooled sample covariance function, hoping to
obtain a more powerful test than some existing tests for the same testing
problem. The asymptotic random expression of this test statistic under the null
hypothesis is obtained. To approximate the null distribution of the proposed
test statistic, we describe a parametric bootstrap method and a non-parametric
bootstrap method. The asymptotic random expression of the proposed test is also
studied under a local alternative and it is shown that the proposed test is
root-$n$ consistent. Intensive simulation studies are conducted to demonstrate
the finite sample performance of the proposed test and it turns out that the
proposed test is indeed more powerful than some existing tests when functional
data are highly correlated. The proposed test is illustrated with three real
data examples.


title: Liveness for Verification

abstract:
  We explore the use of liveness for interactive program verification for a
simple concurrent object language. Our experimental IDE integrates two
(formally dual) kinds of continuous testing into the development environment:
compatibility-checking, which verifies an object's use of other objects, and
compliance-checking, which verifies an object's claim to refine the behaviour
of another object. Source code errors highlighted by the IDE are not static
type errors but the reflection back to the source of runtime errors that occur
in some execution of the system. We demonstrate our approach, and discuss
opportunities and challenges.


title: Two New Tests for Equality of Several Covariance Functions

abstract:
  In this paper, we propose two new tests for testing the equality of the
covariance functions of several functional populations, namely a quasi GPF test
and a quasi $F_{\max}$ test. The asymptotic random expressions of the two tests
under the null hypothesis are derived. We show that the asymptotic null
distribution of the quasi GPF test is a chi-squared-type mixture whose
distribution can be well approximated by a simple scaled chi-squared
distribution. We also adopt a random permutation method for approximating the
null distributions of the quasi GPF and $F_{\max}$ tests. The random
permutation method is applicable for both large and finite sample sizes. The
asymptotic distributions of the two tests under a local alternative are
investigated and they are shown to be root-n consistent. Simulation studies are
presented to demonstrate the finite-sample performance of the new tests against
three existing tests. They show that our new tests are more powerful than the
three existing tests when the covariance functions at different time points
have different scales. An illustrative example is also presented.


title: Efficient Removal Lemmas for Matrices

abstract:
  The authors and Fischer recently proved that any hereditary property of
two-dimensional matrices (where the row and column order is not ignored) over a
finite alphabet is testable with a constant number of queries, by establishing
the following (ordered) matrix removal lemma: For any finite alphabet $\Sigma$,
any hereditary property $\mathcal{P}$ of matrices over $\Sigma$, and any
$\epsilon > 0$, there exists $f_{\mathcal{P}}(\epsilon)$ such that for any
matrix $M$ over $\Sigma$ that is $\epsilon$-far from satisfying $\mathcal{P}$,
most of the $f_{\mathcal{P}}(\epsilon) \times f_{\mathcal{P}}(\epsilon)$
submatrices of $M$ do not satisfy $\mathcal{P}$. Here being $\epsilon$-far from
$\mathcal{P}$ means that one needs to modify at least an $\epsilon$-fraction of
the entries of $M$ to make it satisfy $\mathcal{P}$.
  However, in the above general removal lemma, $f_{\mathcal{P}}(\epsilon)$
grows very fast as a function of $\epsilon^{-1}$, even when $\mathcal{P}$ is
characterized by a single forbidden submatrix. In this work we establish much
more efficient removal lemmas for several special cases of the above problem.
In particular, we show the following: For any fixed $s \times t$ binary matrix
$A$ and any $\epsilon > 0$ there exists $\delta > 0$ polynomial in $\epsilon$,
such that for any binary matrix $M$ in which less than a $\delta$-fraction of
the $s \times t$ submatrices are equal to $A$, there exists a set of less than
an $\epsilon$-fraction of the entries of $M$ that intersects every $A$-copy in
$M$.
  We generalize the work of Alon, Fischer and Newman [SICOMP'07] and make
progress towards proving one of their conjectures. The proofs combine their
efficient conditional regularity lemma for matrices with additional
combinatorial and probabilistic ideas.


title:
Observable Lepton Number Violation with Predominantly Dirac Nature of
  Active Neutrinos

abstract:
  We study a specific version of $SU(2)_R \times SU(2)_L \times U(1)_{B-L}$
models extended by discrete symmetries where the new physics sector responsible
for tiny neutrino masses at leading order remains decoupled from the new
physics sector that can give rise to observable signatures of lepton number
violation such as neutrinoless double beta decay. More specifically, the
dominant contribution to light neutrino masses comes from a one-loop Dirac
mass. At higher loop level, a tiny Majorana mass also appears which remains
suppressed by many order of magnitudes in comparison to the Dirac mass. Such a
model where the active neutrinos are predominantly of Dirac type, also predicts
observable charged lepton flavour violation like $\mu \rightarrow 3e, \mu
\rightarrow e \gamma$ and multi-component dark matter.


title: Estimation in nonlinear regression with Harris recurrent Markov chains

abstract:
  In this paper, we study parametric nonlinear regression under the Harris
recurrent Markov chain framework. We first consider the nonlinear least squares
estimators of the parameters in the homoskedastic case, and establish
asymptotic theory for the proposed estimators. Our results show that the
convergence rates for the estimators rely not only on the properties of the
nonlinear regression function, but also on the number of regenerations for the
Harris recurrent Markov chain. Furthermore, we discuss the estimation of the
parameter vector in a conditional volatility function, and apply our results to
the nonlinear regression with $I(1)$ processes and derive an asymptotic
distribution theory which is comparable to that obtained by Park and Phillips
[Econometrica 69 (2001) 117-161]. Some numerical studies including simulation
and empirical application are provided to examine the finite sample performance
of the proposed approaches and results.


title: A Conjecture Concerning Ball Lightning

abstract:
  There is at present no theory that can explain the curious properties of ball
lightning. This suggests that we may not be using the most appropriate
concepts. The concept of a 'parallel space' may point the way to a valid
theory.


title:
Regenerative Soot-I: Carbon cluster formation in regenerative sooting
  plasmas

abstract:
  Laboratory formation of large carbon clusters with m C atoms where m could be
up to few thousand, in carbonaceous plasma, has been studied by using an
especially designed ion source. Carbon is introduced into the glow discharge
plasma by sputtering of the graphite electrode. Soot dominated plasma is
created whose constituents are carbon clusters. It produces and recycles
cluster containing plasma. Regenerative sooting plasma creates the environment
in which the entire spectrum of clusters that contain the linear chains, rings
and fullerenes. Velocity spectra of the extracted clusters have been measured
with an ExB filter. These spectra indicate and identify the mechanisms
operating in the soot.


title: On-orbit performance of the Gaia CCDs at L2

abstract:
  The European Space Agency's Gaia satellite was launched into orbit around L2
in December 2013 with a payload containing 106 large-format scientific CCDs.
The primary goal of the mission is to repeatedly obtain high-precision
astrometric and photometric measurements of one thousand million stars over the
course of five years. The scientific value of the down-linked data, and the
operation of the onboard autonomous detection chain, relies on the high
performance of the detectors. As Gaia slowly rotates and scans the sky, the
CCDs are continuously operated in a mode where the line clock rate and the
satellite rotation spin-rate are in synchronisation. Nominal mission operations
began in July 2014 and the first data release is being prepared for release at
the end of Summer 2016.
  In this paper we present an overview of the focal plane, the detector system,
and strategies for on-orbit performance monitoring of the system. This is
followed by a presentation of the performance results based on analysis of data
acquired during a two-year window beginning at payload switch-on. Results for
parameters such as readout noise and electronic offset behaviour are presented
and we pay particular attention to the effects of the L2 radiation environment
on the devices. The radiation-induced degradation in the charge transfer
efficiency (CTE) in the (parallel) scan direction is clearly diagnosed;
however, an extrapolation shows that charge transfer inefficiency (CTI) effects
at end of mission will be approximately an order of magnitude less than
predicted pre-flight. It is shown that the CTI in the serial register
(horizontal direction) is still dominated by the traps inherent to the
manufacturing process and that the radiation-induced degradation so far is only
a few per cent. Finally, we summarise some of the detector effects discovered
on-orbit which are still being investigated.


title: Topological *-autonomous categories, revisited

abstract:
  Given an additive equational category with a closed symmetric monoidal
structure and a potential dualizing object, we find sufficient conditions that
the category of topological objects over that category has a good notion of
full subcategories of strong and weakly topologized objects and show that each
is equivalent to the chu category of the original category with respect to the
dualizing object.


title: Quantum objects as elementary units of causality and locality

abstract:
  The author's attempt to construct a local causal model of quantum theory (QT)
that includes quantum field theory (QFT) resulted in the identification of
"quantum objects" as the elementary units of causality and locality. Quantum
objects are collections of particles (including single particles) whose
collective dynamics and measurement results can only be described by the laws
of QT and QFT. Local causal models of quantum objects' internal dynamics are
not possible if a locality is understood as a space-point locality. Within
quantum objects, state transitions may occur which instantly affect the whole
quantum object. The identification of quantum objects as the elementary units
of causality and locality has two primary implications for a causal model of
quantum objects: (1) quantum objects run autonomously with system-state update
frequencies based on their local proper times and with either no or minimal
dependency on external parameters. (2) The laws of physics that describe global
(but relativistic) interrelationships must be translated to a causal model of
interactions between quantum objects and interactions between quantum objects
and the space.


title: Convolutional Recurrent Neural Networks for Music Classification

abstract:
  We introduce a convolutional recurrent neural network (CRNN) for music
tagging. CRNNs take advantage of convolutional neural networks (CNNs) for local
feature extraction and recurrent neural networks for temporal summarisation of
the extracted features. We compare CRNN with three CNN structures that have
been used for music tagging while controlling the number of parameters with
respect to their performance and training time per sample. Overall, we found
that CRNNs show a strong performance with respect to the number of parameter
and training time, indicating the effectiveness of its hybrid structure in
music feature extraction and feature summarisation.


title: Large-scale quantum-emitter arrays in atomically thin semiconductors

abstract:
  The flourishing field of two-dimensional (2D) nanophotonics has generated
much excitement in the quantum technologies community after the identification
of quantum emitters (QEs) in layered materials (LMs). LMs offer many advantages
as platforms for quantum circuits, such as integration within hybrid
technologies, valley degree of freedom and strong spin-orbit coupling. QEs in
LMs, however, suffer from uncontrolled occurrences, added to the uncertainty
over their origin, which has been linked to defects and strain gradients. Here,
we report a scalable method to create arrays of single-photon emitting QEs in
tungsten diselenide (WSe2) and tungsten disulphide (WS2) using a nanopatterned
silica substrate. We obtain devices with QE numbers in the range of hundreds,
limited only by the flake size, and a QE yield approaching unity. The overall
quality of these deterministic QEs surpasses that of their randomly appearing
counterparts, with spectral wanderings of around 0.1 meV, an order of magnitude
lower than previous reports. Our technique solves the scalability challenge for
LM-based quantum photonic devices.


title: Non-random network connectivity comes in pairs

abstract:
  Overrepresentation of bidirectional connections in local cortical networks
has been repeatedly reported and is in the focus of the ongoing discussion of
non-random connectivity. Here we show in a brief mathematical analysis that in
a network in which connection probabilities are symmetric in pairs, $P_{ij} =
P_{ji}$, the occurrence of bidirectional connections and non-random structures
are inherently linked; an overabundance of reciprocally connected pairs emerges
necessarily when the network structure deviates from a random network in any
form.


title: The anomaly of dark matter

abstract:
  2017 observations by Riess and coworkers have indicated that the universe is
expanding some seven percent faster than the currently accepted cosmological
model described. In this paper we argue that this discrepancy can be eliminated
by considering a universe consisting only of matter and dark energy.


title: Evolution of thick domain walls in de Sitter universe

abstract:
  We consider thick domain walls in a de Sitter universe following paper by
Basu and Vilenkin. However, we are interested not only in stationary solutions
found therein, but also investigate the general case of domain wall evolution
with time. When the wall thickness parameter, $\delta_0$, is smaller than
$H^{-1}/\sqrt{2}$, where $H$ is the Hubble parameter in de Sitter space-time,
then the stationary solutions exist, and initial field configurations tend with
time to the stationary ones. However, there are no stationary solutions for
$\delta_0 \geq H^{-1}/\sqrt{2}$. We have calculated numerically the rate of the
wall expansion in this case and have found that the width of the wall grows
exponentially fast for $\delta_0 \gg H^{-1}$. An explanation for the critical
value $\delta_{0c} = H^{-1}/\sqrt{2}$ is also proposed.


title: On the electrostatic equilibrium of charges and cavities in a conductor

abstract:
  We consider a charged conductor of arbitrary shape, in electrostatic
equilibrium, with one or more cavities inside it, and with fixed charges placed
outside the conductors and inside the cavities. The field inside a particular
cavity is then only due to charges within that cavity itself and to the surface
charge induced on the surface of the same cavity. A similar statement holds for
the exterior of the conductor. Although this is an elementary property of
conductors, it is not a trivial statement, as explained in this article.
Undergraduate texts in electrodynamics do not discuss at length or provide a
complete argument for an important problem such as this. Two simple and
complete proofs are provided in this note with the help of the standard
electrostatic uniqueness theorems.


title: Virtual photons in the ground state of a dissipative system

abstract:
  Much of the novel physics predicted to be observable in the ultrastrong
light-matter coupling regime rests on the hybridisation between states with
different numbers of excitations, leading to a population of virtual photons in
the system's ground state. In this article, exploiting an exact diagonalization
approach, we derive both analytical and numerical results for the population of
virtual photons in presence of arbitrary losses. Specialising our results to
the case of Lorentzian resonances we then show that the virtual photon
population is only quantitatively affected by losses, even when those become
the dominant energy scale. Our results demonstrate most of the
ultrastrong-coupling phenomenology can be observed in loss-dominated systems
which are not even in the standard strong coupling regime. We thus open the
possibility to investigate ultrastrong-coupling physics to platforms that were
previously considered unsuitable due to their large losses.


title:
Piezo-generated charge mapping revealed through Direct Piezoelectric
  Force Microscopy

abstract:
  While piezoelectrics and ferroelectrics are playing a key role in many
everyday applications, there are still a number of open questions related to
the physics of those materials. In order to foster the understanding of
piezoelectrics and ferroelectric and pave the way to future applications, the
nanoscale characterization of these materials is essential. In this light, we
have developed a novel AFM based mode that obtains a direct quantitative
analysis of the piezoelectric coefficient d33. This nanoscale tool is capable
of detecting and reveal piezo-charge generation through the direct
piezoelectric effect at the surface of the piezoelectric and ferroelectric
materials. We report the first nanoscale images of the charge generated in a
thick single crystal of Periodically Poled Lithium Niobate (PPLN) and a Bismuth
Ferrite (BiFO3) thin film by applying a force and recording the current
produced by the materials. The quantification of both d33 coefficients for PPLN
and BFO are 13 +- 2 pC/N and 46 +- 7 pC/N respectively, in agreement with the
values reported in the literature. This new mode can operate simultaneously
with PFM mode providing a powerful tool for the electromechanical and
piezo-charge generation characterization of ferroelectric and piezoelectric
materials.


title:
Influence of Plasmonic Array Geometry on Energy Transfer from a Quantum
  Well to a Quantum Dot Layer

abstract:
  A range of seven different Ag plasmonic arrays formed using nanostructures of
varying shape, size and gap were fabricated using helium-ion lithography (HIL)
on an InGaN/GaN quantum well (QW) substrate. The influence of the array
geometry on plasmon-enhanced F\"orster resonance energy transfer (FRET) from a
single InGaN QW to a ~ 80 nm layer of CdSe/ZnS quantum dots (QDs) embedded in a
poly(methyl methacrylate) (PMMA) matrix is investigated. It is shown that the
energy transfer efficiency is strongly dependent on the array properties and an
efficiency of ~ 51% is observed for a nanoring array. There were no signatures
of FRET in the absence of the arrays. The QD acceptor layer emission is highly
sensitive to the array geometry. A model was developed to confirm that the
increase in the QD emission on the QW substrate compared with a GaN substrate
can be attributed solely to plasmon-enhanced FRET. The individual contributions
of direct enhancement of the QD layer emission by the array and the
plasmon-enhanced FRET are separated out, with the QD emission described by the
product of an array emission factor and an energy transfer factor. It is shown
that while the nanoring geometry results in an energy transfer factor of ~ 1.7
the competing quenching by the array, with an array emission factor of ~ 0.7,
results in only an overall gain of ~ 14% in the QD emission. The QD emission
was enhanced by ~ 71% for a nanobox array, resulting from the combination of a
more modest energy transfer factor of 1.2 coupled with an array emission factor
of ~ 1.4.


title:
Universal Distribution of Would-be Topological Zero Modes in Coupled
  Chiral Systems

abstract:
  We consider two quenched, chiral ensembles which are coupled in such a way
that a combined chiral symmetry is preserved. The coupling also links the
topology of the two systems such that the number of exact zero modes in the
coupled system equals the sum of the number of zero modes in the two uncoupled
systems counted with sign. The canceled modes that turn non-topological due to
the coupling become near-zero modes at small coupling. We analyze the
distribution of these would-be zero modes using effective field theory. The
distribution is universal and, in the limit of small coupling, the would-be
zero modes are distributed according to a finite size chiral Gaussian ensemble,
where the width of the distribution scales as the inverse square root of the
volume.


title: Neural Machine Transliteration: Preliminary Results

abstract:
  Machine transliteration is the process of automatically transforming the
script of a word from a source language to a target language, while preserving
pronunciation. Sequence to sequence learning has recently emerged as a new
paradigm in supervised learning. In this paper a character-based
encoder-decoder model has been proposed that consists of two Recurrent Neural
Networks. The encoder is a Bidirectional recurrent neural network that encodes
a sequence of symbols into a fixed-length vector representation, and the
decoder generates the target sequence using an attention-based recurrent neural
network. The encoder, the decoder and the attention mechanism are jointly
trained to maximize the conditional probability of a target sequence given a
source sequence. Our experiments on different datasets show that the proposed
encoder-decoder model is able to achieve significantly higher transliteration
quality over traditional statistical models.


title:
Some theorems on passing from local to global presence of properties of
  functions

abstract:
  When given a class of functions and a finite collection of sets, one might be
interested whether the class in question contains any function whose domain is
a subset of the union of the sets of the given collection and whose
restrictions to all of them belong to this class. The collections with the
formulated property are said to be strongly join permitting for the given class
(the notion of join permitting collection is defined in the same way, but
without the words "a subset of"). Three theorems concerning certain instances
of the problem are proved. A necessary and sufficient condition for being
strongly join permitting is given for the case when, for some $n$, the class
consists of the potentially partial recursive functions of $n$ variables, and
the collection consists of sets of $n$-tuples of natural numbers. The second
theorem gives a sufficient condition for the case when the class consists of
the continuous partial functions between two given topological spaces, and the
collection consists of subsets of the first of them (the condition is also
necessary under a weak assumption on the second one). The third theorem is of a
similar character but, instead of continuity, it concerns computability in the
spirit of the one in effective topological spaces.


title:
The Way We Measure: Comparison of Methods to Derive Radial Surface
  Brightness Profiles

abstract:
  The breaks and truncations in the luminosity profile of face-on spiral
galaxies offer valuable insights in their formation history. The traditional
method of deriving the surface photometry profile for face-on galaxies is to
use elliptical averaging. In this paper, we explore the question whether
elliptical averaging is the best way to do this. We apply two additional
surface photometry methods, one new: principle axis summation, and one old that
has become seldom used: equivalent profiles. These are compared to elliptically
averaged profiles using a set of 29 face-on galaxies. We find that the
equivalent profiles match extremely well with elliptically averaged profiles,
confirming the validity of using elliptical averaging. The principle axis
summation offers a better comparison to edge-on galaxies.


title:
H\"older continuity of bounded, weak solutions of a variational system
  in the critical case

abstract:
  Let $\Omega\subset\mathbb{R}^{2}$ be a bounded, Lipschitz domain. We consider
bounded, weak solutions ($u\in W^{1, 2}\cap L^{\infty}(\Omega;\mathbb{R}^N)$)
of the vector-valued, Euler-Lagrange system: \text{div } \big( A(x,
u)Du\big)=g(x, u, Du)\quad\text{in }\Omega.
  Under natural growth conditions on the principal part and the inhomogeneity,
but without any further restriction on the growth of the inhomogeneity (for
example, via a smallness condition), we use a blow-up argument to prove that
every bounded, weak solution of the system is H\"older continuous. Since the
dimension of $\Omega$ is $2$ and $u\in W^{1, 2}(\Omega;\mathbb{R}^N)$, we are
in the critical setting, and hence, cannot use the Sobolev embedding theorem to
deduce H\"older continuity.
  Our results are connected to a particular case of the open problem of whether
all solutions (and not just extremals) of variational systems are H\"older
continuous in the critical setting.


title: New Strategies for Standard Bases over Z

abstract:
  Experiences with the implementation of strong Gr\"obner bases respectively
standard bases for polynomial rings over principal ideal rings are explained:
different strategies for creating the pair set, methods to avoid coefficient
growth and a normal form algorithm for non-global orderings.


title: Exponential decay of covariances for the supercritical membrane model

abstract:
  We consider the membrane model, that is the centered Gaussian field on
$\mathbb Z^d$ whose covariance matrix is given by the inverse of the discrete
Bilaplacian. We impose a $\delta-$pinning condition, giving a reward of
strength $\varepsilon$ for the field to be $0$ at any site of the lattice. In
this paper we prove that in dimensions $d\geq 5$ covariances of the pinned
field decay at least exponentially, as opposed to the field without pinning,
where the decay is polynomial. The proof is based on estimates for certain
discrete weighted norms, a percolation argument and on a Bernoulli domination
result.


title: A Fast Algorithm for Computing the Truncated Resultant

abstract:
  Let P and Q be two polynomials in K[x, y] with degree at most d, where K is a
field. Denoting by R $\in$ K[x] the resultant of P and Q with respect to y, we
present an algorithm to compute R mod x^k in O~(kd) arithmetic operations in K,
where the O~ notation indicates that we omit polylogarithmic factors. This is
an improvement over state-of-the-art algorithms that require to compute R in
O~(d^3) operations before computing its first k coefficients.


title: Gamma Rays From Blazars

abstract:
  Blazars are high-energy engines providing us natural laboratories to study
particle acceleration, relativistic plasma processes, magnetic field dynamics,
black hole physics. Key informations are provided by observations at
high-energy (in particular by Fermi/LAT) and very-high energy (by Cherenkov
telescopes). I give a short account of the current status of the field, with
particular emphasis on the theoretical challenges connected to the observed
ultra-fast variability events and to the emission of flat spectrum radio
quasars in the very high energy band.


title:
Constitutive relations for electromagnetic field in a form of $6\times
  6$ matrices derived from the geometric algebra

abstract:
  To have a closed system, the Maxwell equations should be supplemented by
constitutive relations which connect the primary electromagnetic fields
$(\bE,\bB)$ with the secondary ones $(\bD,\bH)$ induced in a medium. Recently
[Opt. Commun. \textbf{354}, 259 (2015)] the allowed shapes of the constitutive
relations that follow from the relativistic Maxwell equations formulated in
terms of geometric algebra were constructed by author. In this paper the
obtained general relativistic relations between $(\bD,\bH)$ and $(\bE,\bB)$
fields are transformed to four $6\times 6$ matrices that are universal in
constructing various combinations of constitutive relations in terms of more
popular Gibbs-Heaviside vectorial calculus frequently used to investigate the
electromagnetic wave propagation in anisotropic, birefringent, bianisotropic,
chiral etc media.


title: Transcendental Liouville inequalities on projective varieties

abstract:
  Let $p$ be an algebraic point of a projective variety $X$ defined over a
number field. Liouville inequality tells us that the norm at $p$ of a non
vanishing integral global section of an hermitian line bundle over $X$ is
either zero or it cannot be too small with respect to the $\sup$ norm of the
section itself. We study inequalities similar to Liouville's for subvarietes
and for transcendental points of a projective variety defined over a number
field. We prove that almost all transcendental points verify a good inequality
of Liouville type. We also relate our methods to a (former) conjecture by
Chudnowsky and give two applications to the growth of the number of rational
points of bounded height on the image of an analytic map from a disk to a
projective variety.


title: Exocomet signatures around the A-shell star $\Phi$ Leo?

abstract:
  We present an intensive monitoring of high-resolution spectra of the Ca {\sc
ii} K line in the A7IV shell star $\Phi$ Leo at very short (minutes, hours),
short (night to night), and medium (weeks, months) timescales. The spectra show
remarkable variable absorptions on timescales of hours, days, and months. The
characteristics of these sporadic events are very similar to most that are
observed toward the debris disk host star $\beta$ Pic, which are commonly
interpreted as signs of the evaporation of solid, comet-like bodies grazing or
falling onto the star. Therefore, our results suggest the presence of solid
bodies around $\Phi$ Leo. To our knowledge, with the exception of $\beta$ Pic,
our monitoring has the best time resolution at the mentioned timescales for a
star with events attributed to exocomets. Assuming the cometary scenario and
considering the timescales of our monitoring, our results indicate that $\Phi$
Leo presents the richest environment with comet-like events known to date,
second only to $\beta$ Pic.


title:
Photo-stability of super-hydrogenated PAHs determined by action
  spectroscopy experiments

abstract:
  We have investigated the photo-stability of pristine and super-hydrogenated
pyrene cations C$_{16}$H$_{10+m}^+, m = 0,6, \mathrm{\ or\ } 16$) by means of
gas-phase action spectroscopy. Optical absorption spectra and photo-induced
dissociation mass spectra are presented. By measuring the yield of
mass-selected photo-fragment ions as a function of laser pulse intensity, the
number of photons (and hence the energy) needed for fragmentation of the carbon
backbone was determined. Backbone fragmentation of pristine pyrene ions
(C$_{16}$H$_{10}^+$) requires absorption of three photons of energy just below
3 eV, whereas super-hydrogenated hexahydropyrene (C$_{16}$H$_{16}^+$) must
absorb two such photons and fully hydrogenated hexadecahydropyrene
(C$_{16}$H$_{26}^+$) only a single photon. These results are consistent with
previously reported dissociation energies for these ions. Our experiments
clearly demonstrate that the increased heat capacity from the additional
hydrogen atoms does not compensate for the weakening of the carbon backbone
when pyrene is hydrogenated. In photodissociation regions, super-hydrogenated
Polycyclic Aromatic Hydrocarbons (PAHs) have been proposed to serve as
catalysts for H$_2$-formation. Our results indicate that carbon backbone
fragmentation may be a serious competitor to H$_2$-formation at least for small
hydrogenated PAHs like pyrene.


title: Green-Schwarz superstring on doubled-yet-gauged spacetime

abstract:
  We construct a world-sheet action for Green-Schwarz superstring in terms of
doubled-yet-gauged spacetime coordinates. For an arbitrarily curved NS-NS
background, the action possesses $\mathbf{O}(10,10)$ T-duality,
$\mathbf{Spin}(1,9)\times\mathbf{Spin}(9,1)$ Lorentz symmetry, coordinate gauge
symmetry, spacetime doubled-yet-gauged diffeomorphisms, world-sheet
diffeomorphisms and Weyl symmetry. Further, restricted to flat backgrounds, it
enjoys maximal spacetime supersymmetry and kappa-symmetry. After the auxiliary
coordinate gauge symmetry potential being integrated out, our action can
consistently reduce to the original undoubled Green-Schwarz action. Thanks to
the twofold spin groups, the action is unique: it is specific choices of the
NS-NS backgrounds that distinguish IIA or IIB, as well as lead to
non-Riemannian or non-relativistic superstring a la Gomis-Ooguri which might
deserve the nomenclature, type IIC.


title:
Detection of a ~20 kpc coherent magnetic field in the outskirt of
  merging spirals: the Antennae galaxies

abstract:
  We present a study of the magnetic field properties of NGC 4038/9 (the
`Antennae' galaxies), the closest example of a late stage merger of two spiral
galaxies. Wideband polarimetric observations were performed using the Karl G.
Jansky Very Large Array between 2 and 4 GHz. Rotation measure synthesis and
Faraday depolarization analysis was performed to probe the magnetic field
strength and structure at spatial resolution of $\sim1$ kpc. Highly polarized
emission from the southern tidal tail is detected with intrinsic fractional
polarization close to the theoretical maximum ($0.62\pm0.18$), estimated by
fitting the Faraday depolarization with a volume that is both synchrotron
emitting and Faraday rotating containing random magnetic fields. Magnetic
fields are well aligned along the tidal tail and the Faraday depths shows
large-scale smooth variations preserving its sign. This suggests the field in
the plane of the sky to be regular up to $\sim20$ kpc, which is the largest
detected regular field structure on galactic scales. The equipartition field
strength of $\sim8.5~\mu$G of the regular field in the tidal tail is reached
within a few 100 Myr, likely generated by stretching of the galactic disc field
by a factor of 4--9 during the tidal interaction. The regular field strength is
greater than the turbulent fields in the tidal tail. Our study comprehensively
demonstrates, although the magnetic fields within the merging bodies are
dominated by strong turbulent magnetic fields of $\sim20~\mu$G in strength,
tidal interactions can produce large-scale regular field structure in the
outskirts.


title:
A microscopic cranking model for nuclear collective rotation I:
  rigid-plus-irrotational-flow rotating frame

abstract:
  We derive in a simple manner and from first principles the Inglis
semi-classical phenomenological cranking model for nuclear collective rotation.
The derivation transforms the nuclear Schrodinger equation (instead of the
Hamiltonian) to a rotating frame using a product wavefunction and imposing no
constraints on either the wavefunction or the nucleon motion. The difference
from Inglis model is that the frame rotation is driven by the motions of the
nucleons and not externally. Consequently, the transformed Schrodinger equation
is time-reversal invariant, and the total angular momentum is the sum of those
of the intrinsic system and rotating frame. In this article, we choose the
rotation of the frame to be given by a combination of rigid and irrotational
flows. The dynamic angular velocity of the rotating frame is determined by the
angular momentum of the frame and by a moment of inertia that is determined by
the nature of the flow combination. The intrinsic-system and rotating-frame
angular momenta emerge to have opposite signs. The angular momentum of the
rotating frame is determined from requiring the expectation of the total
angular momentum to have a given value. The transformed Schrodinger equation
has, in addition to the Coriolis energy term, a rigid-flow type kinetic energy
term that is absent from the conventional cranking model Schrodinger equation.
Ignoring the relatively small effect of the fluctuations in the angular
velocity and for a self-consistent deformed harmonic oscillator mean-field
potential, the resulting Schrodinger equation is solved for the ground-state
rotational band excitation energy and quadrupole moment in different
configurations of Ne-20 and the results are compared with those of the
conventional cranking model and empirical data.


title:
The theoretical physics ecosystem behind the discovery of the Higgs
  boson

abstract:
  The discovery of the Higgs boson in 2012 was one of the most significant
developments of science in the last half century. A simplified history has
Peter Higgs positing it in the mid-1960s followed by a long wait while
experimentalists progressively turned up collider energies until it appeared
several decades later. However, in order for both the hypothesis and the
experimental discovery to occur, a vast and complex theory ecosystem had to
thrive in the years before Higgs's hypothesis and in the years that followed,
building up to its discovery. It is further claimed that the Higgs boson
hypothesis was an immoderate speculation, and therefore faith in theory
argumentation and speculation was mandatory for the discovery program to
proceed and reach its fulfillment. The Higgs boson could not have been
discovered experimentally by accident.


title:
Gaia Data Release 1 - The Cepheid & RR Lyrae star pipeline and its
  application to the south ecliptic pole region

abstract:
  We present an overview of the Specific Objects Study (SOS) pipeline developed
within the Coordination Unit 7 (CU7) of the Gaia Data Processing and Analysis
Consortium (DPAC), the coordination unit charged with the processing and
analysis of variable sources observed by Gaia, to validate and fully
characterise Cepheids and RR Lyrae stars observed by the spacecraft. We
describe how the SOS for Cepheids and RR Lyrae stars (SOS Cep&RRL) was
specifically tailored to analyse Gaia's G-band photometric time-series with a
South Ecliptic Pole (SEP) footprint, which covers an external region of the
Large Magellanic Cloud (LMC). G-band time-series photometry and
characterization by the SOS Cep&RRL pipeline (mean magnitude and pulsation
characteristics) are published in Gaia Data Release 1 (Gaia DR1) for a total
sample of 3,194 variable stars, 599 Cepheids and 2,595 RR Lyrae stars, of which
386 (43 Cepheids and 343 RR Lyrae stars) are new discoveries by Gaia. All 3,194
stars are distributed over an area extending 38 degrees on either side from a
point offset from the centre of the LMC by about 3 degrees to the north and 4
degrees to the east. The vast majority, but not all, are located within the
LMC. The published sample also includes a few bright RR Lyrae stars that trace
the outer halo of the Milky Way in front of the LMC.


title: An isoperimetric inequality for antipodal subsets of the discrete cube

abstract:
  A family of subsets of $\{1,2,\ldots,n\}$ is said to be {\em antipodal} if it
is closed under taking complements. We prove a best-possible isoperimetric
inequality for antipodal families of subsets of $\{1,2,\ldots,n\}$. Our
inequality implies that for any $k \in \mathbb{N}$, among all such families of
size $2^k$, a family consisting of the union of a $(k-1)$-dimensional subcube
and its antipode has the smallest possible edge boundary.


title: Lipschitz equivalence of fractals and finite state automaton

abstract:
  The study of Lipschitz equivalence of fractals is a very active topic in
recent years. Most of the studies in literature concern totally disconnected
fractals. In this paper, using finite state automata, we construct a
bi-Lipschitz map between two fractal squares which are not totally
disconnected. This is the first non-trivial map of this type. We also show that
this map is measure-preserving.


title: Effect of Poisson noise on adiabatic quantum control

abstract:
  We present a detailed derivation of the master equation describing a general
time-dependent quantum system with classical Poisson white noise and outline
its various properties. We discuss the limiting cases of Poisson white noise
and provide approximations for the different noise strength regimes. We show
that using the eigenstates of the noise superoperator as a basis can be a
useful way of expressing the master equation. Using this we simulate various
settings to illustrate different effects of Poisson noise. In particular, we
show a dip in the fidelity as a function of noise strength where high fidelity
can occur in the strong noise regime for some cases. We also investigate recent
claims [Jing et al., Phys. Rev. A 89 032110 (2014)] that this type of noise may
improve rather than destroy adiabaticity.


title: Gaia Data Release 1, Pre-processing and source list creation

abstract:
  The first data release from the Gaia mission contains accurate positions and
magnitudes for more than a billion sources, and proper motions and parallaxes
for the majority of the 2.5~million Hipparcos and Tycho-2 stars.
  We describe three essential elements of the initial data treatment leading to
this catalogue: the image analysis, the construction of a source list, and the
near real-time monitoring of the payload health. We also discuss some weak
points that set limitations for the attainable precision at the present stage
of the mission.
  Image parameters for point sources are derived from one-dimensional scans,
using a maximum likelihood method, under the assumption of a line spread
function constant in time, and a complete modelling of bias and background.
These conditions are, however, not completely fulfilled. The Gaia source list
is built starting from a large ground-based catalogue, but even so a
significant number of new entries have been added, and a large number have been
removed. The autonomous onboard star image detection will pick up many spurious
images, especially around bright sources, and such unwanted detections must be
identified. Another key step of the source list creation consists in arranging
the more than $10^{10}$ individual detections in spatially isolated groups that
can be analysed individually.
  Complete software systems have been built for the Gaia initial data
treatment, that manage approximately 50~million focal plane transits daily,
giving transit times and fluxes for 500~million individual CCD images to the
astrometric and photometric processing chains. The software also carries out a
successful and detailed daily monitoring of Gaia health.


title: Polymorphisms and Circuit Complexity

abstract:
  We present a framework for studying circuit complexity that is inspired by
techniques that are used for analyzing the complexity of CSPs. We prove that
the circuit complexity of a Boolean function $f$ is characterized by the
partial polymorphisms of $f$'s truth table. Moreover, the non-deterministic
circuit complexity of $f$ is characterized by the polymorphisms of $f$'s truth
table.


title: Magnetoexcitons in cuprous oxide

abstract:
  Two of the most striking experimental findings when investigating exciton
spectra in cuprous oxide using high-resolution spectroscopy are the
observability and the fine structure splitting of $F$ excitons reported by J.
Thewes et al. [Phys. Rev. Lett. 115, 027402 (2015)]. These findings show that
it is indispensable to account for the complex valence band structure and the
cubic symmetry of the solid in the theory of excitons. This is all the more
important for magnetoexcitons, where the external magnetic field reduces the
symmetry of the system even further. We present the theory of excitons in
$\mathrm{Cu_{2}O}$ in an external magnetic field and especially discuss the
dependence of the spectra on the direction of the external magnetic field,
which cannot be understood from a simple hydrogen-like model. Using
high-resolution spectroscopy, we also present the corresponding experimental
spectra for cuprous oxide in Faraday configuration. The theoretical results and
experimental spectra are in excellent agreement as regards not only the
energies but also the relative oscillator strengths. Furthermore, this
comparison allows for the determination of the fourth Luttinger parameter
$\kappa$ of this semiconductor.


title: Non-Hermitian-assisted enhancement precision of parameter estimation

abstract:
  Recently, Zhong et al. [Phys. Rev. A 87, 022337(2013)] investigated the
dynamics of quantum Fisher information (QFI) in the presence of decoherence. We
here reform their results and propose two schemes to enhance and preserve the
QFIs for a qubit system subjected to a decoherence noisy environment by
applying $\textit{non-Hermitian}$ operators process. The proposed schemes are
related to the $\textit{prior}$ (or the $\textit{post}$ ) non-Hermitian
operator process corresponding to before (or after) the interest system suffers
from decoherence, respectively. Resorting to the Bloch sphere representation,
we derive the exact analytical expressions of the QFIs with respect to the
amplitude parameter $\theta$ and the phase parameter $\phi$, and in detail
investigate the influence of $\textit{non-Hermitian}$ operator parameters on
the QFIs. Compared with purity decoherence process (without non-Hermitian
operator process), we find that the $\textit{post non-Hermitian}$ operator
process can potentially enhance and preserve the QFIs by choosing appropriate
$\textit{non-Hermitian}$ operator parameters, while with the help of the
$\textit{prior non-Hermitian}$ operator process one could completely eliminate
the effect of decoherence to improve the parameters estimation. Finally, a
generalized non-Hermitian operator parameters effect on the parameters
estimation is also considered.


title: On the finiteness of the discrete spectrum of a 3x3 operator matrix

abstract:
  An operator matrix $H$ associated with a lattice system describing three
particles in interactions, without conservation of the number of particles, is
considered. The structure of the essential spectrum of $H$ is described by the
spectra of two families of the generalized Friedrichs models. A symmetric
version of the Weinberg equation for eigenvectors of $H$ is obtained. The
conditions which guarantee the finiteness of the number of discrete eigenvalues
located below the bottom of the three-particle branch of the essential spectrum
of $H$ is found.


title: Magnetoexcitons break antiunitary symmetries

abstract:
  We show analytically and numerically that the application of an external
magnetic field to highly excited Rydberg excitons breaks all antiunitary
symmetries in the system. Only by considering the complete valence band
structure of a direct band gap cubic semiconductor, the Hamiltonian of excitons
leads to the statistics of a Gaussian unitary ensemble (GUE) without the need
for interactions with other quasi-particles like phonons. Hence, we give
theoretical evidence for a spatially homogeneous system breaking all
antiunitary symmetries.

categories: cond-mat.mes-hall cond-mat.mtrl-sci nlin.CD quant-ph


title: Magnetic field effects in electron systems with imperfect nesting

abstract:
  We analyze the effects of an applied magnetic field on the phase diagram of a
weakly-correlated electron system with imperfect nesting. The Hamiltonian under
study describes two bands: electron and hole ones. Both bands have spherical
Fermi surfaces, whose radii are slightly mismatched due to doping. These types
of models are often used in the analysis of magnetic states in chromium and its
alloys, superconducting iron pnictides, AA-type bilayer graphene, borides, etc.
At zero magnetic field, the uniform ground state of the system turns out to be
unstable against electronic phase separation. The applied magnetic field
affects the phase diagram in several ways. In particular, the Zeeman term
stabilizes new antiferromagnetic phases. It also significantly shifts the
boundaries of inhomogeneous (phase-separated) states. At sufficiently high
fields, the Landau quantization gives rise to oscillations of the order
parameters and of the N\'eel temperature as a function of the magnetic field.


title:
The CoRoT-GES Collaboration. Improving Red Giants spectroscopic surface
  gravity and abundances with asteroseismology

abstract:
  Nowadays large spectroscopic surveys, like the Gaia-ESO Survey (GES), provide
unique stellar databases for better investigating the formation and evolution
of our Galaxy. Great attention must be paid to the accuracy of the basic
stellar properties derived: large uncertainties in stellar parameters lead to
large uncertainties in abundances, distances and ages. Asteroseismology has a
key role in this context: when seismic information is combined with information
derived from spectroscopic analysis, highly precise constraints on distances,
masses, extinction and ages of Red Giants can be obtained. In the light of this
promising joint-action, we started the CoRoT-GES collaboration. We present a
set of 1,111 CoRoT stars, observed by GES from December 2011 to July 2014,
these stars belong to the CoRoT field LRc01, pointing at the inner Galactic
Disk. Among these stars, 534 have reliable global seismic parameters. By
combining seismic informations and spectroscopy, we derived precise stellar
parameters, ages, kinematic and orbital parameters and detailed element
abundances for this sample of stars. We also show that, thanks to
asteroseismology, we are able to obtain a higher precision than what can be
achieved by the standard spectroscopic means. This sample of CoRoT Red Giants,
spanning Galactocentric distances from 5 to 8 kpc and a wide age interval (1-13
Gyrs), provides us a representative sample for the inner disk population.


title: Document Filtering for Long-tail Entities

abstract:
  Filtering relevant documents with respect to entities is an essential task in
the context of knowledge base construction and maintenance. It entails
processing a time-ordered stream of documents that might be relevant to an
entity in order to select only those that contain vital information.
State-of-the-art approaches to document filtering for popular entities are
entity-dependent: they rely on and are also trained on the specifics of
differentiating features for each specific entity. Moreover, these approaches
tend to use so-called extrinsic information such as Wikipedia page views and
related entities which is typically only available only for popular head
entities. Entity-dependent approaches based on such signals are therefore
ill-suited as filtering methods for long-tail entities. In this paper we
propose a document filtering method for long-tail entities that is
entity-independent and thus also generalizes to unseen or rarely seen entities.
It is based on intrinsic features, i.e., features that are derived from the
documents in which the entities are mentioned. We propose a set of features
that capture informativeness, entity-saliency, and timeliness. In particular,
we introduce features based on entity aspect similarities, relation patterns,
and temporal expressions and combine these with standard features for document
filtering. Experiments following the TREC KBA 2014 setup on a publicly
available dataset show that our model is able to improve the filtering
performance for long-tail entities over several baselines. Results of applying
the model to unseen entities are promising, indicating that the model is able
to learn the general characteristics of a vital document. The overall
performance across all entities---i.e., not just long-tail entities---improves
upon the state-of-the-art without depending on any entity-specific training
data.


title:
A multiplicative process for generating the rank-order distribution of
  UK election results

abstract:
  Human dynamics and sociophysics suggest statistical models that may explain
and provide us with a better understanding of social phenomena. Here we propose
a generative multiplicative decrease model that gives rise to a rank-order
distribution and allows us to analyse the results of the last three UK
parliamentary elections. We provide empirical evidence that the additive
Weibull distribution, which can be generated from our model, is a close fit to
the electoral data, offering a novel interpretation of the recent election
results.


title: St\"ackel-type dynamic model of the Galaxy based on maser kinematic data

abstract:
  A dynamic model of the Galaxy is constructed based on kinematic data for
masers with trigonometric parallaxes. Maser data is used to compute the model
potential in the Galactic plane. The potential is then generalized to three
dimensions assuming the existence of a third quadratic integral of motion. The
resulting Galactic model potential is of St\"ackel's type. The corresponding
space density function is determined from Poisson's equation.


title:
Inclusive Single-Spin Asymmetries, Quark-Photon, and Quark-Quark
  Correlations

abstract:
  We consider quark-photon correlations that have been proposed as a source for
single-spin asymmetries in inclusive deep-inelastic scattering. A new sum rule
for these correlators is derived and its phenomenological consequences are
discussed. The results are interpreted within the context of an intuitive
'electrodynamic lensing' picture.


title: Even Good Bots Fight: The Case of Wikipedia

abstract:
  In recent years, there has been a huge increase in the number of bots online,
varying from Web crawlers for search engines, to chatbots for online customer
service, spambots on social media, and content-editing bots in online
collaboration communities. The online world has turned into an ecosystem of
bots. However, our knowledge of how these automated agents are interacting with
each other is rather poor. Bots are predictable automatons that do not have the
capacity for emotions, meaning-making, creativity, and sociality and it is
hence natural to expect interactions between bots to be relatively predictable
and uneventful. In this article, we analyze the interactions between bots that
edit articles on Wikipedia. We track the extent to which bots undid each
other's edits over the period 2001-2010, model how pairs of bots interact over
time, and identify different types of interaction trajectories. We find that,
although Wikipedia bots are intended to support the encyclopedia, they often
undo each other's edits and these sterile "fights" may sometimes continue for
years. Unlike humans on Wikipedia, bots' interactions tend to occur over longer
periods of time and to be more reciprocated. Yet, just like humans, bots in
different cultural environments may behave differently. Our research suggests
that even relatively "dumb" bots may give rise to complex interactions, and
this carries important implications for Artificial Intelligence research.
Understanding what affects bot-bot interactions is crucial for managing social
media well, providing adequate cyber-security, and designing well functioning
autonomous vehicles.


title:
Detecting Fast Time Variations in the Supernova Neutrino Flux with
  Hyper-Kamiokande

abstract:
  For detection of neutrinos from galactic supernovae, the planned
Hyper-Kamiokande detector will be the first detector that delivers both a high
event rate (about one third of the IceCube rate) and event-by-event energy
information. In this thesis, we use a three-dimensional computer simulation by
the Garching group to find out whether this additional information can be used
to improve the detection prospects of fast time variations in the neutrino
flux.
  We find that the amplitude of SASI oscillations of the neutrino number flux
is energy-dependent. However, in this simulation, the larger amplitude in some
energy bins is not sufficient to counteract the increased noise caused by the
lower event rate. Finally, we derive a condition describing when it is
advantageous to consider an energy bin instead of the total signal and show
that this condition is satisfied if the oscillation of the mean neutrino energy
is increased slightly.

categories: physics.ins-det astro-ph.HE astro-ph.IM hep-ex


title:
A semimetal nanowire rectifier: balancing quantum confinement and
  surface electronegativity

abstract:
  For semimetal nanowires with diameters smaller than a few tens of nanometers,
a semimetal-to-semiconductor transition is observed as the emergence of an
energy band gap resulting from quantum confinement. Quantum confinement in a
semimetal results in either lifting of the degeneracy of the conduction and
valence bands in a zero gap semimetal, or shifting of bands with a negative
energy overlap to form conduction and valence bands. For semimetal nanowires
with diameters below 10 nanometer, the magnitude of the band gap can become
significantly larger than the thermal energy at room temperature resulting in a
new class of semiconductors relevant for nanoelectronics with critical
dimensions on the order of a few atomic lengths. The smaller a nanowire's
diameter, the larger its surface-to-volume ratio thus leading to an increasing
impact of surface chemistry on its electronic structure. Energy level shifts to
states in the vicinity of the Fermi level due to the electronegativity of
surface terminating species are shown to be comparable in magnitude to quantum
confinement effects at nanowire diameters of a few nanometer; these two effects
can be used to counteract one another leading to semimetallic behavior for
nanowire cross sections at which the quantum confinement effect would otherwise
dominate. Abruptly changing the surface terminating species along the length of
a nanowire leads to an abrupt change in the surface electronegativity. This can
result in the formation of a semimetal-semiconductor junction within a
monomaterial nanowire, without the need for impurity doping nor requiring the
formation of a heterojunction.


title: A family of two generator non-Hopfian groups

abstract:
  We construct $2$-generator non-Hopfian groups $G_m, m=3, 4, 5, \dots$, where
each $G_m$ has a specific presentation $G_m=\langle a, b \, | \,
u_{r_{m,0}}=u_{r_{m,1}}=u_{r_{m,2}}= \cdots =1 \rangle$ which satisfies small
cancellation conditions $C(4)$ and $T(4)$. Here, $u_{r_{m,i}}$ is the single
relator of the upper presentation of the $2$-bridge link group of slope
$r_{m,i}$, where $r_{m,0}=[m+1,m,m]$ and $r_{m,i}=[m+1,m-1,(i-1)\langle m
\rangle,m+1,m]$ in continued fraction expansion for every integer $i \ge 1$.


title: Gray-box inference for structured Gaussian process models

abstract:
  We develop an automated variational inference method for Bayesian structured
prediction problems with Gaussian process (GP) priors and linear-chain
likelihoods. Our approach does not need to know the details of the structured
likelihood model and can scale up to a large number of observations.
Furthermore, we show that the required expected likelihood term and its
gradients in the variational objective (ELBO) can be estimated efficiently by
using expectations over very low-dimensional Gaussian distributions.
Optimization of the ELBO is fully parallelizable over sequences and amenable to
stochastic optimization, which we use along with control variate techniques and
state-of-the-art incremental optimization to make our framework useful in
practice. Results on a set of natural language processing tasks show that our
method can be as good as (and sometimes better than) hard-coded approaches
including SVM-struct and CRFs, and overcomes the scalability limitations of
previous inference algorithms based on sampling. Overall, this is a fundamental
step to developing automated inference methods for Bayesian structured
prediction.


title: A Spectral "schematization" of Homotopy Types

abstract:
  Toen has interpreted the schematization problem as originally imagined by
Grothendieck in "Pursuing Stacks" in such a way that solution(s) to this
problem could be given. As he pointed out, there are many solutions available,
and he gave two constructions solving this problem. What we do in the present
work is reconsider what Grothendieck initially had in mind and develop a
formalism that provides a concept of "schematization" and corresponding
homotopy groups of "schematized" homotopy types. In our view this can be
realized if we generalize topological spaces to symmetric spectra, and the
mapping spaces Map(S,A) in the category of symmetric sequences play the role of
homotopy groups, S the sphere spectrum, A a symmetric spectrum.


title: Biconservative surfaces in BCV-spaces

abstract:
  Biconservative hypersurfaces are hypersurfaces with conservative
stress-energy tensor with respect to the bienergy functional, and form a
geometrically interesting family which includes that of biharmonic
hypersurfaces. In this paper we study biconservative surfaces in the
3-dimensional Bianchi-Cartan-Vranceanu spaces, obtaining their characterization
in the following cases: when they form a constant angle with the Hopf vector
field; when they are SO(2)-invariant.


title: Symmetron and de Sitter attractor in a teleparallel model of cosmology

abstract:
  In the teleparallel framework of cosmology, a quintessence with non-minimal
couplings to the scalar torsion and a boundary term is considered. A conformal
coupling to matter density is also taken into account. It is shown that the
model can describe the onset of cosmic acceleration after an epoch of matter
dominated era, where dark energy is negligible, via $Z_2$ symmetry breaking.
While the conformal coupling holds the Universe in a state with zero dark
energy density in the early epoch, the non-minimal couplings lead the Universe
to a stable state with de Sitter expansion at the late time.


title: Toward an Algebraic Theory of Systems

abstract:
  We propose the concept of a system algebra with a parallel composition
operation and an interface connection operation, and formalize
composition-order invariance, which postulates that the order of composing and
connecting systems is irrelevant, a generalized form of associativity.
Composition-order invariance explicitly captures a common property that is
implicit in any context where one can draw a figure (hiding the drawing order)
of several connected systems, which appears in many scientific contexts. This
abstract algebra captures settings where one is interested in the behavior of a
composed system in an environment and wants to abstract away anything internal
not relevant for the behavior. This may include physical systems, electronic
circuits, or interacting distributed systems.
  One specific such setting, of special interest in computer science, are
functional system algebras, which capture, in the most general sense, any type
of system that takes inputs and produces outputs depending on the inputs, and
where the output of a system can be the input to another system. The behavior
of such a system is uniquely determined by the function mapping inputs to
outputs. We consider several instantiations of this very general concept. In
particular, we show that Kahn networks form a functional system algebra and
prove their composition-order invariance.
  Moreover, we define a functional system algebra of causal systems,
characterized by the property that inputs can only influence future outputs,
where an abstract partial order relation captures the notion of "later". This
system algebra is also shown to be composition-order invariant and appropriate
instantiations thereof allow to model and analyze systems that depend on time.


title:
Bias Cancellation in One-Determinant Fixed-Node Diffusion Monte Carlo:
  Insights from Fermionic Occupation Numbers

abstract:
  Accuracy of the fixed-node diffusion Monte Carlo (FN-DMC) depends on the node
location of the best available trial state $\Psi_T$. The practical FN-DMC
approaches available for large systems rely on compact yet effective $\Psi_T$s
containing explicitly correlated single Slater determinant (SD). However, SD
nodes may be better suited to one system than to another, which may possibly
lead to inaccurate FN-DMC energy differences. It remains a challenge, how to
estimate inequivalency or appropriateness of SDs. Here we use the differences
of a measure based on Euclidean distance between the natural orbital occupation
number (NOON) vector of the Slater determinant (SD) from the exact solution in
the NOON vector space, that can be viewed as a measure of SD inequivalency and
a measure of the expected degree of nondynamic-correlation-related bias in
FN-DMC energy differences. This is explored on a set of small noncovalent
complexes and covalent bond breaking of Si$_2$ vs. N$_2$. It turns out that
NOON-based measures well reflect the magnitude and sign of the bias present in
the data available, thus providing new insights to the nature of bias
cancellation in SD FN-DMC energy differences.


title: The Read-Out Shutter Unit of the Euclid VIS Instrument

abstract:
  Euclid is the second medium-size mission (M2) of the ESA Cosmic Vision
Program, currently scheduled for a launch in 2020. The two instruments on-board
Euclid, VIS and NISP, will provide key measurements to investigate the nature
of dark energy, advancing our knowledge on cosmology. We present in this
contribution the development and manufacturing status of the VIS Read-out
Shutter Unit, whose main function is to prevent direct light from falling onto
the VIS CCDs during the read-out of the scientific exposures and to allow the
dark-current/bias calibrations of the instrument.


title: Lipschitz invariance of walk dimension on connected self-similar sets

abstract:
  Walk dimension is an important conception in analysis of fractals. In this
paper we prove that the walk dimension of a connected compact set possessing an
Alfors regular measure is an invariant under Lipschitz transforms. As an
application, we show some generalized Sierpi\'nski gaskets are not Lipschitz
equivalent.


title: Synthetic foundations of cevian geometry, IV: the TCC-perspector theorem

abstract:
  In this paper we give a completely synthetic proof of the TCC-perspector
theorem, that the isogonal conjugate $\gamma(H)$ of the generalized orthocenter
$H$ (defined in Part III of this series of papers), with respect to a triangle
$ABC$ and a point $P$, is the perspector of the tangential triangle of $ABC$
and the circumcevian triangle (both with respect to the circumcircle) of the
isogonal conjugate $\gamma(Q)$, where $Q$ is the complement of the isotomic
conjugate $P'$ of the point $P$.


title: Smartphone Schlieren

abstract:
  We present a schlieren system comprised of 3D printed optical mounts, a
sub-$10 mirror, and a smartphone camera. The system is intended to make
schlieren imaging accessible to K-through-12 students, educators, as well as
hobbyists. In the manuscript, we detail the design of the system, provide
source files for continued iteration, and show some example schlieren images
and videos of a butane lighter, a jet of compressed air, and an electric stove.

categories: physics.ed-ph physics.flu-dyn physics.ins-det physics.optics


title:
Totally Antimagic Total labeling of Ladders, Prisms and Generalised
  Pertersen graphs

abstract:
  Given a graph $G$, a total labeling on $G$ is called edge-antimagic total
(respectively, vertex-antimagic total) if all edge-weights (respectively,
vertex-weights) are pairwise distinct. If a labeling on $G$ is simultaneously
edge-antimagic total and vertex-antimagic total, it is called a totally
antimagic total labeling. A graph that admits totally antimagic total labeling
is called a totally antimagic total graph. In this paper, we prove that
ladders, prisms and generalised Pertersen graphs are totally antimagic total
graphs. We also show that the chain graph of totally antimagic total graphs is
a totally antimagic total graph.


title:
Lam-Tung relation breaking in $Z^0$ hadroproduction as a probe of parton
  transverse momentum

abstract:
  The Lam-Tung relation breaking coefficient $A_{\mathrm{LT}} = A_0 - A_2$ in
the Drell-Yan dilepton angular distributions in the $Z^0$ boson mass region at
the LHC is analyzed in the $k_T$-factorization approach. This observable was
recently measured with high precision by ATLAS collaboration. Within the
$k_T$-factorization approach we perform an approximate ${\cal
O}(\alpha_{\mathrm{em}}\alpha_s^2)$ calculation of the off-shell parton hard
matrix elements in which we include the leading tree level contributions of
valence quarks and off-shell gluons: the $q_{\mathrm{val}} g^* \to qZ^0$
channel and the $g^*g^* \to q\bar q Z^0$ channel. The resulting
$A_{\mathrm{LT}}$ exhibits high sensitivity to the gluon transverse momentum
distribution (TMD). Several gluon TMDs are probed derived from the CCFM and
BFKL evolution equations, and given by QCD-inspired phenomenological
parameterizations. The ATLAS data favor a simple "Weizs\"acker-Williams" (WW)
hard gluon TMD with the asymptotic behavior of one-gluon exchange at large
gluon transverse momenta and moderate $x$. It is verified that the proposed
approach with the WW gluon TMD describes well also the $A_0$ and $A_2$ angular
coefficients at the $Z^0$ peak, as well as the Drell-Yan dilepton mass
distribution at lower masses. We conclude that inclusion of gluon transverse
momentum effects improves description of the angular distributions of Drell-Yan
dileptons and that the Drell-Yan scattering provides an excellent probe of the
parton TMDs.


title: TristouNet: Triplet Loss for Speaker Turn Embedding

abstract:
  TristouNet is a neural network architecture based on Long Short-Term Memory
recurrent networks, meant to project speech sequences into a fixed-dimensional
euclidean space. Thanks to the triplet loss paradigm used for training, the
resulting sequence embeddings can be compared directly with the euclidean
distance, for speaker comparison purposes. Experiments on short (between 500ms
and 5s) speech turn comparison and speaker change detection show that
TristouNet brings significant improvements over the current state-of-the-art
techniques for both tasks.


title:
Study of Brownian functionals in physically motivated model with purely
  time dependent drift and diffusion

abstract:
  In this paper, we investigate a Brownian motion (BM) with purely time
dependent drift and difusion by suggesting and examining several Brownian
functionals which characterize the lifetime and reactivity of such stochastic
processes. We introduce several probability distribution functions (PDFs)
associated with such time dependent BMs. For instance, for a BM with initial
starting point $x_0$, we derive analytical expressions for : (i) the PDF
$P(t_f|x_0)$ of the first passage time $t_f$ which specify the lifetime of such
stochastic process, (ii) the PDF $P(A|x_0)$ of the area A till the first
passage time and it provides us numerous valuable information about the
effective reactivity of the process, (iii) the PDF $P(M)$ associated with the
maximum size M of the BM process before the first passage time, and (iv)the
joint PDF $P(M; t_m)$ of the maximum size M and its occurrence time $t_m$
before the first passage time. These distributions are examined for the power
law time time dependent drift and diffusion. A simple illustrative example for
the stochastic model of water resources availability in snowmelt dominated
regions with power law time dependent drift and diffusion is demonstrated in
details. We motivate our study with approximate calculation of an unsolved
problem of Brownian functionals including inertia.


title:
Gaia Data Release 1: Astrometry - one billion positions, two million
  proper motions and parallaxes

abstract:
  Gaia Data Release 1 (Gaia DR1) contains astrometric results for more than 1
billion stars brighter than magnitude 20.7 based on observations collected by
the Gaia satellite during the first 14 months of its operational phase. We give
a brief overview of the astrometric content of the data release and of the
model assumptions, data processing, and validation of the results. For stars in
common with the Hipparcos and Tycho-2 catalogues, complete astrometric
single-star solutions are obtained by incorporating positional information from
the earlier catalogues. For other stars only their positions are obtained by
neglecting their proper motions and parallaxes. The results are validated by an
analysis of the residuals, through special validation runs, and by comparison
with external data. Results. For about two million of the brighter stars (down
to magnitude ~11.5) we obtain positions, parallaxes, and proper motions to
Hipparcos-type precision or better. For these stars, systematic errors
depending e.g. on position and colour are at a level of 0.3 milliarcsecond
(mas). For the remaining stars we obtain positions at epoch J2015.0 accurate to
~10 mas. Positions and proper motions are given in a reference frame that is
aligned with the International Celestial Reference Frame (ICRF) to better than
0.1 mas at epoch J2015.0, and non-rotating with respect to ICRF to within 0.03
mas/yr. The Hipparcos reference frame is found to rotate with respect to the
Gaia DR1 frame at a rate of 0.24 mas/yr. Based on less than a quarter of the
nominal mission length and on very provisional and incomplete calibrations, the
quality and completeness of the astrometric data in Gaia DR1 are far from what
is expected for the final mission products. The results nevertheless represent
a huge improvement in the available fundamental stellar data and practical
definition of the optical reference frame.


title:
DbarD and DD pair production at the LHCb in the parton Reggeization
  approach

abstract:
  We study the inclusive DbarD and DD pair production in proton-proton
collisions at the LHC at lead- ing order of the parton Reggeization approach
endowed with universal scale-depended fragmen- tation functions for c-quark to
D-meson and for gluon to D-meson transitions. We have described DbarD and DD
distributions in azimuthal angle, as well as transverse momentum, rapidity
distance, and invariant mass measured in the region of large rapidity 2 < y < 4
by the LHCb Collabora- tion at the LHC without free parameters. We have used
Reggeized amplitudes for the processes RR - gg and RR - c barc which are
obtained accordingly to Feynman rules of the L.N. Lipatov effective theory of
Reggeized partons, and Kimber-Martin-Ryskin model for unintegrated gluon
distribution function in a proton with Martin-Stirling-Thorne-Watt collinear
parton distributions as inputs.


title:
A measurement of material in the ATLAS tracker using secondary hadronic
  interactions in 7 TeV pp collisions

abstract:
  Knowledge of the material in the ATLAS inner tracking detector is crucial in
understanding the reconstruction of charged-particle tracks, the performance of
algorithms that identify jets containing b-hadrons and is also essential to
reduce background in searches for exotic particles that can decay within the
inner detector volume. Interactions of primary hadrons produced in pp
collisions with the material in the inner detector are used to map the location
and amount of this material. The hadronic interactions of primary particles may
result in secondary vertices, which in this analysis are reconstructed by an
inclusive vertex-finding algorithm. Data were collected using minimum-bias
triggers by the ATLAS detector operating at the LHC during 2010 at
centre-of-mass energy $\sqrt{s}$ = 7 TeV, and correspond to an integrated
luminosity of $19$ nb$^{-1}$. Kinematic properties of these secondary vertices
are used to study the validity of the modelling of hadronic interactions in
simulation. Secondary-vertex yields are compared between data and simulation
over a volume of about 0.7 m$^3$ around the interaction point, and agreement is
found within overall uncertainties.


title: Generalized flexibility-rigidity index

abstract:
  Flexibility-rigidity index (FRI) has been developed as a robust, accurate and
efficient method for macromolecular thermal fluctuation analysis and B-factor
prediction. The performance of FRI depends on its formulations of rigidity
index and flexibility index. In this work, we introduce alternative rigidity
and flexibility formulations. The structure of the classic Gaussian surface is
utilized to construct a new type of rigidity index, which leads to a new class
of rigidity densities with the classic Gaussian surface as a special case.
Additionally, we introduce a new type of flexibility index based on the domain
indicator property of normalized rigidity density. These generalized FRI (gFRI)
methods have been extensively validated by the B-factor predictions of 364
proteins. Significantly outperforming the classic Gaussian network model (GNM),
gFRI is a new generation of methodologies for accurate, robust and efficient
analysis of protein flexibility and fluctuation. Finally, gFRI based molecular
surface generation and flexibility visualization are demonstrated.


title:
Many-terminal Majorana island: from Topological to Multi-Channel Kondo
  Model

abstract:
  We study Kondo screening obtained by coupling Majorana bound states, located
on a topological superconducting island, to interacting electronic reservoirs.
At the charge degeneracy points of the island, we formulate an exact mapping
onto the spin-$1/2$ multi-channel Kondo effect. The coupling to Majorana
fermions transforms the tunneling terms into effective fermionic bilinear
contributions with a Luttinger parameter $K$ in the leads that is effectively
doubled. For strong interaction, $K=1/2$, the intermediate fixed point of the
standard multi-channel Kondo model is exactly recovered. It evolves with $K$
and connects to strong coupling in non-interacting case $K=1$, with maximum
conductance between the leads and robustness against channel asymmetries
similarly to the topological Kondo effect. For a number of leads above four,
there exists a window of Luttinger parameters in which a quantum phase
transition can occur between the strong coupling topological Kondo state and
the partially conducting multi-channel Kondo state.


title: Stability of the phase motion in race-track microtons

abstract:
  We model the phase oscillations of electrons in race-track microtrons by
means of an area preserving map with a fixed point at the origin, which
represents the synchronous trajectory of a reference particle in the beam. We
study the nonlinear stability of the origin in terms of the synchronous phase
-- the phase of the synchronous particle at the injection. We estimate the size
and shape of the stability domain around the origin, whose main connected
component is enclosed by the last rotational invariant curve. We describe the
evolution of the stability domain as the synchronous phase varies. Besides, we
approximate some rotational invariant curves by level sets of certain
Hamiltonians. Finally, we clarify the role of the stable and unstable invariant
curves of some hyperbolic (fixed or periodic) points.


title: Efficient softmax approximation for GPUs

abstract:
  We propose an approximate strategy to efficiently train neural network based
language models over very large vocabularies. Our approach, called adaptive
softmax, circumvents the linear dependency on the vocabulary size by exploiting
the unbalanced word distribution to form clusters that explicitly minimize the
expectation of computation time. Our approach further reduces the computational
time by exploiting the specificities of modern architectures and matrix-matrix
vector operations, making it particularly suited for graphical processing
units. Our experiments carried out on standard benchmarks, such as EuroParl and
One Billion Word, show that our approach brings a large gain in efficiency over
standard approximations while achieving an accuracy close to that of the full
softmax. The code of our method is available at
https://github.com/facebookresearch/adaptive-softmax.


title: Network susceptibilities: theory and applications

abstract:
  We introduce the concept of network susceptibilities quantifying the response
of the collective dy- namics of a network to small parameter changes. We
distinguish two types of susceptibilities: vertex susceptibilities and edge
susceptibilities, measuring the responses due to changes in the properties of
units and their interactions, respectively. We derive explicit forms of network
susceptibilities for oscillator networks close to steady states and offer
example applications for Kuramoto-type phase- oscillator models, power grid
models and generic flow models. Focusing on the role of the network topology
implies that these ideas can be easily generalized to other types of networks,
in particular those characterizing flow, transport, or spreading phenomena. The
concept of network susceptibil- ities is broadly applicable and may
straightforwardly be transferred to all settings where networks responses of
the collective dynamics to topological changes are essential.


title:
A general fluctuation-response relation for noise variations and its
  application to driven hydrodynamic experiments

abstract:
  The effect of a change of noise amplitudes in overdamped diffusive systems is
linked to their unperturbed behavior by means of a nonequilibrium
fluctuation-response relation. This formula holds also for systems with
state-independent nontrivial diffusivity matrices, as we show with an
application to an experiment of two trapped and hydrodynamically coupled
colloids, one of which is subject to an external random forcing that mimics an
effective temperature. The nonequilibrium susceptibility of the energy to a
variation of this driving is an example of our formulation, which improves an
earlier version, as it does not depend on the time-discretization of the
stochastic dynamics. This scheme holds for generic systems with additive noise
and can be easily implemented numerically, thanks to matrix operations.


title: Markov Chains from Descent Operators on Combinatorial Hopf Algebras

abstract:
  We develop a general theory for Markov chains whose transition probabilities
are the coefficients of descent operators on combinatorial Hopf algebras. These
model the breaking-then-recombining of combinational objects. Examples include
the various card-shuffles of Diaconis, Fill and Pitman, Fulman's
restriction-then-induction chains on the representations of the symmetric
group, and a plethora of new chains on trees, partitions and permutations. The
eigenvalues of these chains can be calculated in a uniform manner using Hopf
algebra structure theory, and there is a simple expression for their stationary
distributions. For an important subclass of chains analogous to the
top-to-random shuffle, we derive a full right eigenbasis, from which follow
exact expressions for expectations of certain statistics of interest. This
greatly generalises the coproduct-then-product chains previously studied in
joint work with Persi Diaconis and Arun Ram.


title: The discrete spherical averages over a family of sparse sequences

abstract:
  We initiate the study of the $\ell^p(\mathbb{Z}^d)$-boundedness of the
arithmetic spherical maximal function over sparse sequences. We state a
folklore conjecture for lacunary sequences, a key example of Zienkiewicz and
prove new bounds for a family of sparse sequences that achieves the endpoint of
the Magyar--Stein--Wainger theorem for the full discrete spherical maximal
function. Perhaps our most interesting result is the boundedness of a discrete
spherical maximal function in $\mathbb{Z}^4$ over an infinite, albeit sparse,
set of radii. Our methods include the Kloosterman refinement for the Fourier
transform of the spherical measure (introduced by Magyar) and Weil bounds for
Kloosterman sums which are utilized by a new further decomposition of spherical
measure.


title:
An epidemiological model of viral infections in a Varroa-infested bee
  colony: the case of a bee-dependent mite population size

abstract:
  In recent years the spread of the ectoparasitic mite Varroa destructor has
become the most serious threat to worldwide apiculture. In the model presented
here we extend the bee population dynamics with mite viral epidemiology
examined in an earlier paper by allowing a bee-dependent mite population size.
The results of the analysis match field observations well and give a clear
explanation of how Varroa affects the epidemiology of certain naturally
occurring bee viruses, causing considerable damages to colonies. The model
allows only four possible stable equilibria, using known field parameters. The
first one contains only the thriving healthy bees. Here the disease is
eradicated and also the mites are wiped out. Alternatively, we find the
equilibrium still with no mite population, but with endemic disease among the
thriving bee population. Thirdly, infected bees coexist with the mites in the
Varroa invasion scenario; in this situation the disease invades the hive,
driving the healthy bees to extinction and therefore affecting all the bees.
Coexistence is also possible, with both populations of bees and mites thriving
and with the disease endemically affecting both species. The analysis is in
line with field observations in natural honey bee colonies. Namely, these
diseases are endemic and if the mite population is present, necessarily the
viral infection occurs. Further, in agreement with the fact that the presence
of Varroa increments the viral transmission, the whole bee population may
become infected when the disease vector is present in the beehive. Also, a low
horizontal transmission rate of the virus among the honey bees will help in
protecting the bee colonies from Varroa infestation and viral epidemics.


title:
Noise optimization of the source follower of a CMOS pixel using BSIM3
  noise model

abstract:
  CMOS imagers are becoming increasingly popular in astronomy. A very low noise
level is required to observe extremely faint targets and to get high-precision
flux measurements. Although CMOS technology offers many advantages over CCDs, a
major bottleneck is still the read noise. To move from an industrial CMOS
sensor to one suitable for scientific applications, an improved design that
optimizes the noise level is essential. Here, we study the 1/f and thermal
noise performance of the source follower (SF) of a CMOS pixel in detail. We
identify the relevant design parameters, and analytically study their impact on
the noise level using the BSIM3v3 noise model with an enhanced model of gate
capacitance. Our detailed analysis shows that the dependence of the 1/f noise
on the geometrical size of the source follower is not limited to minimum
channel length, compared to the classical approach to achieve the minimum 1/f
noise. We derive the optimal gate dimensions (the width and the length) of the
source follower that minimize the 1/f noise, and validate our results using
numerical simulations. By considering the thermal noise or white noise along
with 1/f noise, the total input noise of the source follower depends on the
capacitor ratio CG/CFD and the drain current (Id). Here, CG is the total gate
capacitance of the source follower and CFD is the total floating diffusion
capacitor at the input of the source follower. We demonstrate that the optimum
gate capacitance (CG) depends on the chosen bias current but ranges from CFD/3
to CFD to achieve the minimum total noise of the source follower. Numerical
calculation and circuit simulation with 180nm CMOS technology are performed to
validate our results.


title:
Community detection in weighted brain connectivity networks beyond the
  resolution limit

abstract:
  Graph theory provides a powerful framework to investigate brain functional
connectivity networks and their modular organization. However, most graph-based
methods suffer from a fundamental resolution limit that may have affected
previous studies and prevented detection of modules, or communities, that are
smaller than a specific scale. Surprise, a resolution-limit-free function
rooted in discrete probability theory, has been recently introduced and applied
to brain networks, revealing a wide size-distribution of functional modules, in
contrast with many previous reports. However, the use of Surprise is limited to
binary networks, while brain networks are intrinsically weighted, reflecting a
continuous distribution of connectivity strengths between different brain
regions. Here, we propose Asymptotical Surprise, a continuous version of
Surprise, for the study of weighted brain connectivity networks, and validate
this approach in synthetic networks endowed with a ground-truth modular
structure. We compare Asymptotical Surprise with leading community detection
methods currently in use and show its superior sensitivity in the detection of
small modules even in the presence of noise and intersubject variability such
as those observed in fMRI data. Finally, we apply our novel approach to
functional connectivity networks from resting state fMRI experimenta, and
demonstrate a heterogeneous modular organization, with a wide distribution of
clusters spanning multiple scales.


title:
Applying the relativistic quantization condition to a three-particle
  bound state in a periodic box

abstract:
  Using our recently developed relativistic three-particle quantization
condition, we study the finite-volume energy shift of a spin-zero
three-particle bound state. We reproduce the result obtained using
non-relativistic quantum mechanics by Meissner, Rios and Rusetsky, and
generalize the result to a moving frame.


title: The Origin of Motif Families in Food Webs

abstract:
  Food webs have been found to exhibit remarkable motif profiles, patterns in
the relative prevalences of all possible three-species sub-graphs, and this has
been related to ecosystem properties such as stability and robustness.
Analysing 46 food webs of various kinds, we find that most food webs fall into
one of two distinct motif families. The separation between the families is well
predicted by a global measure of hierarchical order in directed networks -
trophic coherence. We find that trophic coherence is also a good predictor for
the extent of omnivory, defined as the tendency of species to feed on multiple
trophic levels. We compare our results to a network assembly model that admits
tunable trophic coherence via a single free parameter. The model is able to
generate food webs in either of the two families by varying this parameter, and
correctly classifies almost all the food webs in our database. This establishes
a link between global order and local preying patterns in food webs.