title:
Search for Higgs and $Z$ Boson Decays to $\phi\,\gamma$ with the ATLAS
  Detector

abstract:
  A search for the decays of the Higgs and $Z$ bosons to a $\phi$ meson and a
photon is performed with a $pp$ collision data sample corresponding to an
integrated luminosity of 2.7 fb$^{-1}$ collected at $\sqrt{s}=$13 TeV with the
ATLAS detector at the LHC. No significant excess of events is observed above
the background, and 95% confidence level upper limits on the branching
fractions of the Higgs and $Z$ boson decays to $\phi\,\gamma$ of
1.4$\times$10$^{-3}$ and 8.3$\times$10$^{-6}$, respectively, are obtained.


title:
Parsimonious Mixed-Effects HodgeRank for Crowdsourced Preference
  Aggregation

abstract:
  In crowdsourced preference aggregation, it is often assumed that all the
annotators are subject to a common preference or utility function which
generates their comparison behaviors in experiments. However, in reality
annotators are subject to variations due to multi-criteria, abnormal, or a
mixture of such behaviors. In this paper, we propose a parsimonious
mixed-effects model based on HodgeRank, which takes into account both the fixed
effect that the majority of annotators follows a common linear utility model,
and the random effect that a small subset of annotators might deviate from the
common significantly and exhibits strongly personalized preferences. HodgeRank
has been successfully applied to subjective quality evaluation of multimedia
and resolves pairwise crowdsourced ranking data into a global consensus ranking
and cyclic conflicts of interests. As an extension, our proposed methodology
further explores the conflicts of interests through the random effect in
annotator specific variations. The key algorithm in this paper establishes a
dynamic path from the common utility to individual variations, with different
levels of parsimony or sparsity on personalization, based on newly developed
Linearized Bregman Algorithms with Inverse Scale Space method. Finally the
validity of the methodology are supported by experiments with both simulated
examples and three real-world crowdsourcing datasets, which shows that our
proposed method exhibits better performance (i.e. smaller test error) compared
with HodgeRank due to its parsimonious property.


title: The Friedmann cosmology: mountains and wells, as real and potential

abstract:
  The Universe dynamical equations discovered by Alexander Friedmann in 1922
are simple enough to be clear for undergraduate students or even for smart
senior schoolkids. The background cosmology driven by the dust-like matter and
by positive cosmological constant in General Relativity can be understood as a
radial motion of a test particle in the superposition of Newtonian and
anti-Hook potentials according to Newtonian mechanics. This analogy was
mentioned by George Gamov in his book (1952). The present paper was written as
a pedagogical and methodological text.


title:
Charge density wave with meronlike spin texture induced by a lateral
  superlattice in a two-dimensional electron gas

abstract:
  The combined effect of a lateral square superlattice potential and the
Coulomb interaction on the ground state of a two-dimensional electron gas in a
perpendicular magnetic field is studied for different rational values of
$\Gamma$, the inverse of the number of flux quanta per unit cell of the
external potential, at filling factor $\nu =1$ in Landau level $N=0.$ When
Landau level mixing and disorder effects are neglected, increasing the strength
$W_{0}$ of the potential induces a transition, at a critical strength
$W_{0}^{\left( c\right) },$ from a uniform and fully spin polarized state to a
two-dimensional charge density wave (CDW) with a meronlike spin texture at each
maximum and minimum of the CDW. The collective excitations of this vortex-CDW
are similar to those of the Skyrme crystal that is expected to be the ground
state near filling factor $\nu =1$. In particular, a broken U(1) symmetry in
the vortex-CDW results in an extra gapless phase mode that could provide a fast
channel for the relaxation of nuclear spins. The average spin polarization $%
S_{z}$ changes in a continuous or discontinuous manner as $W_{0}$ is increased
depending on whether $\Gamma \in \left[ 1/2,1\right] $ or $\Gamma \in \left[
0,1/2\right] .$ The phase mode and the meronlike spin texture disappear at
large value of $W_{0},$ leaving as the ground state a partially spin-polarized
CDW if $\Gamma \neq 1/2$ or a spin-unpolarized CDW if $\Gamma =1/2.$


title: Circle Packings with Generalized Branching

abstract:
  Attempts to build a discrete theory for rational maps on the sphere via
circle packing have foundered on discretization effects in locating branch
points. The authors remove this impediment by introducing generalized branch
points. A generalized branch point need no longer be attached to an individual
circle, but with the help of chaperones and other devices, can be positioned
anywhere that the geometry requires. The effects will be illustrated in images
and videos as we use generalized branching to fix flaws in discrete Ahlfors and
Weierstrasse functions.


title: Topological embeddings of disks via configuration categories

abstract:
  The functor that takes a manifold to its configuration category exhibits a
type of full faithfulness in some cases.


title: Multi-modal image retrieval with random walk on multi-layer graphs

abstract:
  The analysis of large collections of image data is still a challenging
problem due to the difficulty of capturing the true concepts in visual data.
The similarity between images could be computed using different and possibly
multimodal features such as color or edge information or even text labels. This
motivates the design of image analysis solutions that are able to effectively
integrate the multi-view information provided by different feature sets. We
therefore propose a new image retrieval solution that is able to sort images
through a random walk on a multi-layer graph, where each layer corresponds to a
different type of information about the image data. We study in depth the
design of the image graph and propose in particular an effective method to
select the edge weights for the multi-layer graph, such that the image ranking
scores are optimised. We then provide extensive experiments in different
real-world photo collections, which confirm the high performance of our new
image retrieval algorithm that generally surpasses state-of-the-art solutions
due to a more meaningful image similarity computation.


title:
Detecting phase transitions and crossovers in Hubbard models using the
  fidelity susceptibility

abstract:
  A generalized version of the fidelity susceptibility of single-band and
multi-orbital Hubbard models is systematically studied using single-site
dynamical mean-field theory in combination with a hybridization expansion
continuous-time quantum Monte Carlo impurity solver. We find that the fidelity
susceptibility is extremely sensitive to changes in the state of the system. It
can be used as a numerically inexpensive tool to detect and characterize a
broad range of phase transitions and crossovers in Hubbard models, including
(orbital-selective) Mott metal-insulator transitions, high-spin to low-spin
transitions, Fermi-liquid to non-Fermi-liquid crossovers, and spin-freezing
crossovers.


title: Performance Optimization of WSNs using External Information

abstract:
  The goal of this work is to describe a self-management system that correlates
data sensed by different Wireless Sensor Networks (WSNs) and adjusts the number
of active nodes in each network to provide an appropriate amount of
measurements. The architecture considers the factors that make the external
data relevant to the local network, such as the distance between covered areas,
the relation between the types of sensed data and the reliability of the
measurements. As a result, the operation of each network will be tuned to
trade-off the accuracy of the measurements and the power consumption.


title: Effect of Quantum Tunneling on Spin Hall Magnetoresistance

abstract:
  We present a formalism that simultaneously incorporates the effect of quantum
tunneling and spin diffusion on spin Hall magnetoresistance observed in normal
metal/ferromagnetic insulator bilayers (such as Pt/YIG) and normal
metal/ferromagnetic metal bilayers (such as Pt/Co), in which the angle of
magnetization influences the magnetoresistance of the normal metal. In the
normal metal side the spin diffusion is known to affect the landscape of the
spin accumulation caused by spin Hall effect and subsequently the
magnetoresistance, while on the ferromagnet side the quantum tunneling effect
is detrimental to the interface spin current which also affects the spin
accumulation. The influence of generic material properties such as spin
diffusion length, layer thickness, interface coupling, and insulating gap can
be quantified in a unified manner, and experiments that reveal the quantum
feature of the magnetoresistance are suggested.


title: The contact process as seen from a random walk

abstract:
  We consider a random walk on top of the contact process on $\mathbb{Z}^d$
with $d\geq 1$. In particular, we focus on the "contact process as seen from
the random walk". Under the assumption that the infection rate of the contact
process is large or the jump rate of the random walk is small, we show that
this process has at most two extremal measures. Moreover, the convergence to
these extremal measures is characterised by whether the contact process
survives or dies out, similar to the complete convergence theorem known for the
ordinary contact process. Using this, we furthermore provide a law of large
numbers for the random walk which holds under general assumptions on the jump
probabilities of the random walk.


title: Comparing Poisson Sigma Model with A-model

abstract:
  We discuss the A-model as a gauge fixing of the Poisson Sigma Model with
target a symplectic structure. We complete the discussion in [arXiv:0706.3164],
where a gauge fixing defined by a compatible complex structure was introduced,
by showing how to recover the A-model hierarchy of observables in terms of the
AKSZ observables. Moreover, we discuss the off-shell supersymmetry of the
A-model as a residual BV symmetry of the gauge-fixed PSM action.


title:
An innovative silicon photomultiplier digitizing camera for gamma-ray
  astronomy

abstract:
  The single-mirror small-size telescope (SST-1M) is one of the three proposed
designs for the small-size telescopes (SSTs) of the Cherenkov Telescope Array
(CTA) project. The SST-1M will be equipped with a 4 m-diameter segmented mirror
dish and an innovative fully digital camera based on silicon photo-multipliers
(SiPMs). Since the SST sub-array will consist of up to 70 telescopes, the
challenge is not only to build a telescope with excellent performance, but also
to design it so that its components can be commissioned, assembled and tested
by industry. In this paper we review the basic steps that led to the design
concepts for the SST-1M camera and the ongoing realization of the first
prototype, with focus on the innovative solutions adopted for the photodetector
plane and the readout and trigger parts of the camera. In addition, we report
on results of laboratory measurements on real scale elements that validate the
camera design and show that it is capable of matching the CTA requirements of
operating up to high-moon-light background conditions.


title: Anyons in three dimensions with geometric algebra

abstract:
  Even though it has been almost a century since quantum mechanics planted
roots, the field has its share of unresolved problems. It could be the result
of a wrong mathematical structure providing inadequate understanding of the
quantum phenomena.


title:
Series expansions for Maass forms on the full modular group from the
  Farey transfer operators

abstract:
  We deepen the study of the relations previously established by Mayer, Lewis
and Zagier, and the authors, among the eigenfunctions of the transfer operators
of the Gauss and the Farey maps, the solutions of the Lewis-Zagier three-term
functional equation and the Maass forms on the modular surface
$PSL(2,\Z)\backslash \HH$. In particular we introduce an "inverse" of the
integral transform studied by Lewis and Zagier, and use it to obtain new series
expansions for the Maass cusp forms and the non-holomorphic Eisenstein series
restricted to the imaginary axis. As corollaries we obtain further information
on the Fourier coefficients of the forms, including a new series expansion for
the divisor function.


title: VLBA observations of radio faint Fermi-LAT sources above 10 GeV

abstract:
  The first Fermi-LAT High-energy source catalog (1FHL), containing gamma-ray
sources detected above 10 GeV, is an ideal sample to characterize the physical
properties of the most extreme gamma-ray sources. We investigate the pc scale
properties of a sub-sample of radio faint 1FHL sources with the aim to confirm
the proposed blazar associations, by revealing a compact high brightness
temperature radio core, and we propose new low-frequency counterparts for the
unassociated gamma-ray sources (UGS). Moreover, we increase the number of 1FHL
sources with high resolution observations to explore the possible connection
between radio and gamma rays at E >10 GeV. We observed 84 1FHL sources, mostly
blazars of High Synchrotron Peaked (HSP) type, in the northern sky with the
Very Long Baseline Array (VLBA) at 5 GHz. These sources lack high resolution
radio observations and have at least one NVSS counterpart within the 95%
confidence radius. For those sources without a well identified radio
counterpart we exploit the VLBA multiple phase-center correlation capability to
discern among the possible low-frequency candidates. For about 93% of the
sources of our sample we reveal a compact high brightness temperature radio
core, supporting their proposed blazar association. The vast majority of the
detected sources are radio weak, with a median VLBI flux density value of 16.3
mJy. For the detected sources we obtain an average brightness temperature of
the order of $2\times10^{10} \, \rm{K}$. We find a compact component for 16
UGS, for which we propose a new low-frequency association. We find brightness
temperature values which do not require high Doppler factors, and are in
agreement with the expected values for the equipartition of energy between
particles and magnetic field. We find strong indications about the blazar
nature of all of the detected UGS, for which we propose new low-frequency
associations.


title: Dependence of X-Ray Burst Models on Nuclear Reaction Rates

abstract:
  X-ray bursts are thermonuclear flashes on the surface of accreting neutron
stars and reliable burst models are needed to interpret observations in terms
of properties of the neutron star and the binary system. We investigate the
dependence of X-ray burst models on uncertainties in (p,$\gamma$),
($\alpha$,$\gamma$), and ($\alpha$,p) nuclear reaction rates using fully
self-consistent burst models that account for the feedbacks between changes in
nuclear energy generation and changes in astrophysical conditions. A two-step
approach first identified sensitive nuclear reaction rates in a single-zone
model with ignition conditions chosen to match calculations with a
state-of-the-art 1D multi-zone model based on the {\Kepler} stellar evolution
code. All relevant reaction rates on neutron deficient isotopes up to mass 106
were individually varied by a factor of 100 up and down. Calculations of the 84
highest impact reaction rate changes were then repeated in the 1D multi-zone
model. We find a number of uncertain reaction rates that affect predictions of
light curves and burst ashes significantly. The results provide insights into
the nuclear processes that shape X-ray burst observables and guidance for
future nuclear physics work to reduce nuclear uncertainties in X-ray burst
models.


title:
The usability canary in the security coal mine: A cognitive framework
  for evaluation and design of usable authentication solutions

abstract:
  Over the past 15 years, researchers have identified an increasing number of
security mechanisms that are so unusable that the intended users either
circumvent them or give up on a service rather than suffer the security. With
hindsight, the reasons can be identified easily enough: either the security
task itself is too cumbersome and/or time-consuming, or it creates high
friction with the users` primary task. The aim of the research presented here
is to equip designers who select and implement security mechanisms with a
method for identifying the ``best fit`` security mechanism at the design stage.
Since many usability problems have been identified with authentication, we
focus on ``best fit`` authentication, and present a framework that allows
security designers not only to model the workload associated with a particular
authentication method, but more importantly to model it in the context of the
user`s primary task. We draw on results from cognitive psychology to create a
method that allows a designer to understand the impact of a particular
authentication method on user productivity and satisfaction. In a validation
study using a physical mockup of an airline check-in kiosk, we demonstrate that
the model can predict user performance and satisfaction. Furthermore, design
experts suggested personalized order recommendations which were similar to our
model`s predictions. Our model is the first that supports identification of a
holistic fit between the task of user authentication and the context in which
it is performed. When applied to new systems, we believe it will help designers
understand the usability impact of their security choices and thus develop
solutions that maximize both.


title: The Homogeneity Scale of the universe

abstract:
  In this study, we probe the cosmic homogeneity with the BOSS CMASS galaxy
sample in the redshift region of $0.43 < z < 0.7$. We use the normalised
counts-in-spheres estimator $\mathcal{N}(<r)$ and the fractal correlation
dimension $\mathcal{D}_{2}(r)$ to assess the homogeneity scale of the universe.
We verify that the universe becomes homogenous on scales greater than
$\mathcal{R}_{H} \simeq 64.3\pm1.6\ h^{-1}Mpc$, consolidating the Cosmological
Principle with a consistency test of $\Lambda$CDM model at the percentage
level. Finally, we explore the evolution of the homogeneity scale in redshift.


title: Detection of Electromagnetic Inclusions using Topological Sensitivity

abstract:
  In this article a topological sensitivity framework for far field detection
of a diametrically small electromagnetic inclusion is established. The cases of
single and multiple measurements of the electric far field scattering amplitude
at a fixed frequency are taken into account. The performance of the algorithm
is analyzed theoretically in terms of its resolution and sensitivity for
locating an inclusion. The stability of the framework with respect to
measurement and medium noises is discussed. Moreover, the quantitative results
for signal-to-noise ratio are presented. A few numerical results are presented
to illustrate the detection capabilities of the proposed framework with single
and multiple measurements.


title:
Practical Design and Implementation of Metamaterial-Enhanced Magnetic
  Induction Communication

abstract:
  Although wireless communications in complex environments, such as
underground, underwater, and indoor, can enable a large number of novel
applications, their performances are constrained by lossy media and complicated
structures. Magnetic Induction (MI) has been proved to be an efficient solution
to achieve reliable communication in such environments. However, due to the
small coil antenna's physical limitation, MI's communication range is still
very limited if devices are required to be portable. To this end,
Metamaterial-enhanced Magnetic Induction (M$^2$I) communication has been
proposed and the theoretical results predict that it can significantly increase
the communication performance, namely, data rate and communication range.
Nevertheless, currently, the real implementation of M$^2$I is still a challenge
and there is no guideline on design and fabrication of spherical metamaterials.
In this paper, a practical design is proposed by leveraging a spherical coil
array to realize M$^2$I. We prove that the effectively negative permeability
can be achieved and there exists a resonance condition where the radiated
magnetic field can be significantly amplified. The radiation and communication
performances are evaluated and full-wave simulation is conducted to validate
the design objectives. By using the spherical coil array-based M$^2$I, the
communication range can be significantly extended, exactly as we predicted in
the ideal M$^2$I model. Finally, the proposed M$^2$I antenna is implemented and
tested in various environments.


title: Kinetic intermittency in magnetized plasma turbulence

abstract:
  We employ magnetized plasma turbulence, described by a gyrokinetic formalism
in an interval ranging from the end of the fluid scales to the electron
gyroradius, to introduce the first study of kinetic intermittency, in which
nonlinear structures formed directly in the distribution functions are analyzed
by accounting for velocity space correlations generated by linear (Landau
resonance) and nonlinear phase mixing. Electron structures are found to be
strongly intermittent and dominated by linear phase mixing, while nonlinear
phase mixing dominates the weakly intermittent ions. This is the first time
spatial intermittency and linear phase mixing are shown to be self-consistently
linked for the electrons and, as the magnetic field follows the intermittency
of the electrons at small scales, explain why magnetic islands are places
dominated by Landau damping in steady state turbulence.


title:
Exponential decay of the size of spectral gaps for quasiperiodic
  Schr\"odinger operators

abstract:
  In the following we are interested in the spectral gaps of discrete
quasiperiodic Schr\"odinger operators when the frequency is Diophantine, the
potential is analytic, and in the subcritical regime. The gap-labelling theorem
asserts in this context that each gap has constant rotation number, labeled by
some integer. We prove that the size of these gaps decays exponentially fast
with respect to their label. This refines a subexponential bound obtained
previously by Sana Ben Hadj Amor. Contrary to her approach, which is based on
KAM methods, the arguments in the present paper are non-perturbative, and use
quantitative reducibility estimates obtained by Artur Avila and Svetlana
Jitomirskaya. As a corollary of our result, we show that under the previous
assumptions, the spectrum is 1/2-homogeneous.


title: Relative tensor triangular Chow groups for coherent algebras

abstract:
  We apply the machinery of relative tensor triangular Chow groups to the
action of the derived category of quasi-coherent sheaves on a noetherian scheme
$X$ on the derived category of quasi-coherent $\mathcal{A}$-modules, where
$\mathcal{A}$ is a (not necessarily commutative) quasi-coherent
$\mathcal{O}_X$-algebra. When $\mathcal{A}$ is commutative and coherent, we
recover the tensor triangular Chow groups of the relative Spec of
$\mathcal{A}$. We also obtain concrete descriptions for integral group algebras
and hereditary orders over curves, and we investigate the relation of these
invariants to the classical ideal class group of an order. An important tool
for these computations is a new description of relative tensor triangular Chow
groups as the image of a map in the K-theoretic localization sequence
associated to a certain Verdier localization.


title: The Structure of the Kauffman Bracket Skein Algebra at Roots of Unity

abstract:
  This paper is focused on the structure of the Kauffman bracket skein algebra
of a punctured surface at roots of unity. A criterion that determines when a
collection of skeins forms a basis of the skein algebra as an extension over
the $SL(2,{\mathbb C})$ characters of the fundamental group of the surface,
with appropriate localization is given. This is used to prove that when the
algebra is localized so that every nonzero element of the center has a
multiplicative inverse, that it is a division algebra. Finally, it is proved
that the localized skein algebra can be split over its center as a tensor
product of two commutative subalgebras.


title: Bayesian Inference of Bijective Non-Rigid Shape Correspondence

abstract:
  Many algorithms for the computation of correspondences between deformable
shapes rely on some variant of nearest neighbor matching in a descriptor space.
Such are, for example, various point-wise correspondence recovery algorithms
used as a postprocessing stage in the functional correspondence framework. In
this paper, we show that such frequently used techniques in practice suffer
from lack of accuracy and result in poor surjectivity. We propose an
alternative recovery technique guaranteeing a bijective correspondence and
producing significantly higher accuracy. We derive the proposed method from a
statistical framework of Bayesian inference and demonstrate its performance on
several challenging deformable 3D shape matching datasets.


title:
On modeling and global solutions for d.c. optimization problems by
  canonical duality theory

abstract:
  This paper presents a canonical d.c. (difference of canonical and convex
functions) programming problem, which can be used to model general global
optimization problems in complex systems. It shows that by using the canonical
duality theory, a large class of nonconvex minimization problems can be
equivalently converted to a unified concave maximization problem over a convex
domain, which can be solved easily under certain conditions. Additionally, a
detailed proof for triality theory is provided, which can be used to identify
local extremal solutions. Applications are illustrated and open problems are
presented.


title: Propeller effect in the transient X-ray pulsar SMC X-2

abstract:
  We report the results of the monitoring campaign of the transient X-ray
pulsar SMC X-2 performed with the Swift/XRT telescope over the period of 2015
September - 2016 January during the Type II outburst. During this event, the
bolometric luminosity of the source ranged from $\simeq10^{39}$ down to
several$\times10^{34}$ erg/s. Moreover, we discovered its dramatic drop by a
factor of more than 100 below the limiting value of $L_{\rm
lim}\simeq4\times10^{36}$ erg/s, which can be interpreted as a transition to
the propeller regime. These measurements make SMC X-2 the sixth pulsating X-ray
source where such a transition is observed and allow us to estimate the
magnetic field of the neutron star in the system $B\simeq3\times10^{12}$ G,
which is in agreement with independent results of the spectral analysis.


title:
Learning in Quantum Control: High-Dimensional Global Optimization for
  Noisy Quantum Dynamics

abstract:
  Quantum control is valuable for various quantum technologies such as
high-fidelity gates for universal quantum computing, adaptive quantum-enhanced
metrology, and ultra-cold atom manipulation. Although supervised machine
learning and reinforcement learning are widely used for optimizing control
parameters in classical systems, quantum control for parameter optimization is
mainly pursued via gradient-based greedy algorithms. Although the quantum
fitness landscape is often compatible with greedy algorithms, sometimes greedy
algorithms yield poor results, especially for large-dimensional quantum
systems. We employ differential evolution algorithms to circumvent the
stagnation problem of non-convex optimization. We improve quantum control
fidelity for noisy system by averaging over the objective function. To reduce
computational cost, we introduce heuristics for early termination of runs and
for adaptive selection of search subspaces. Our implementation is massively
parallel and vectorized to reduce run time even further. We demonstrate our
methods with two examples, namely quantum phase estimation and quantum gate
design, for which we achieve superior fidelity and scalability than obtained
using greedy algorithms.


title:
Beyond histograms: efficiently estimating radial distribution functions
  via spectral Monte Carlo

abstract:
  Despite more than 40 years of research in condensed-matter physics,
state-of-the-art approaches for simulating the radial distribution function
(RDF) g(r) still rely on binning pair-separations into a histogram. Such
methods suffer from undesirable properties, including subjectivity, high
uncertainty, and slow rates of convergence. Moreover, such problems go
undetected by the metrics often used to assess RDFs. To address these issues,
we propose (I) a spectral Monte Carlo (SMC) method that yields g(r) as an
analytical series expansion; and (II) a Sobolev norm that assesses the quality
of RDFs by quantifying their fluctuations. Using the latter, we show that,
relative to histogram-based approaches, SMC reduces by orders of magnitude both
the noise in g(r) and the number of pair separations needed for acceptable
convergence. Moreover, SMC reduces subjectivity and yields simple,
differentiable formulas for the RDF, which are useful for tasks such as
coarse-grained force-field calibration via iterative Boltzmann inversion.


title: Dual representations for systemic risk measures

abstract:
  The financial crisis showed the importance of measuring, allocating and
regulating systemic risk. Recently, the systemic risk measures that can be
decomposed into an aggregation function and a scalar measure of risk, received
a lot of attention. In this framework, capital allocations are added after
aggregation and can represent bailout costs. More recently, a framework has
been introduced, where institutions are supplied with capital allocations
before aggregation. This yields an interpretation that is particularly useful
for regulatory purposes. In each framework, the set of all feasible capital
allocations leads to a multivariate risk measure. In this paper, we present
dual representations for scalar systemic risk measures as well as for the
corresponding multivariate risk measures concerning capital allocations. Our
results cover both frameworks: aggregating after allocating and allocating
after aggregation. As examples, we consider the aggregation mechanisms of the
Eisenberg-Noe model as well as those of the resource allocation and network
flow models.


title: Integral cohomology of the Generalized Kummer fourfold

abstract:
  We describe the integral cohomology of the Generalized Kummer fourfold giving
an explicit basis, using Hilbert scheme cohomology and tools developed by
Hassett and Tschinkel. Then we apply our results to a IHS variety with
singularities, obtained by a partial resolution of the Generalized Kummer
quotiented by a symplectic involution. We calculate the Beauville--Bogomolov
form of this new variety, presenting the first example of such a form that is
odd.


title: Tight lower bounds for the complexity of multicoloring

abstract:
  In the multicoloring problem, also known as ($a$:$b$)-coloring or $b$-fold
coloring, we are given a graph G and a set of $a$ colors, and the task is to
assign a subset of $b$ colors to each vertex of G so that adjacent vertices
receive disjoint color subsets. This natural generalization of the classic
coloring problem (the $b=1$ case) is equivalent to finding a homomorphism to
the Kneser graph $KG_{a,b}$, and gives relaxations approaching the fractional
chromatic number.
  We study the complexity of determining whether a graph has an
($a$:$b$)-coloring. Our main result is that this problem does not admit an
algorithm with running time $f(b)\cdot 2^{o(\log b)\cdot n}$, for any
computable $f(b)$, unless the Exponential Time Hypothesis (ETH) fails. A
$(b+1)^n\cdot \text{poly}(n)$-time algorithm due to Nederlof [2008] shows that
this is tight. A direct corollary of our result is that the graph homomorphism
problem does not admit a $2^{O(n+h)}$ algorithm unless ETH fails, even if the
target graph is required to be a Kneser graph. This refines the understanding
given by the recent lower bound of Cygan et al. [SODA 2016].
  The crucial ingredient in our hardness reduction is the usage of detecting
matrices of Lindstr\"om [Canad. Math. Bull., 1965], which is a combinatorial
tool that, to the best of our knowledge, has not yet been used for proving
complexity lower bounds. As a side result, we prove that the running time of
the algorithms of Abasi et al. [MFCS 2014] and of Gabizon et al. [ESA 2015] for
the r-monomial detection problem are optimal under ETH.


title:
Effect of Cationic and Anionic Surfactants on the Application of Calcium
  Carbonate Nanoparticles in Paper Coating

abstract:
  Modification of calcium carbonate particles with surfactant significantly
improves the properties of the calcium carbonate coating on paper. Unmodified
and CTAB and oleate-modified calcium carbonate nanoparticles were prepared
using the wet carbonation technique for paper coating. CTAB (cationic
surfactant) and sodium oleate (anionic surfactant) were used to modify the
size, morphology, and surface properties of the precipitated nanoparticles. The
obtained particles were characterized by XRD, FT-IR spectroscopy, zeta
potential measurements, TGA and TEM. Coating colors were formulated from the
prepared unmodified and modified calcium carbonates and examined by creating a
thin coating layer on reference paper. The effect of calcium carbonate particle
size and surface modification on paper properties, such as coating thickness,
coating weight, surface roughness, air permeability, brightness, whiteness,
opacity, and hydrophobicity, were investigated and compared with GCC calcium
carbonate-coated papers. The obtained calcium carbonate nanoparticles are in
the calcite phase. The morphology of the prepared calcium carbonate
nanoparticles is rhombohedral, and the average particle diameter is <100 nm.
Compared to commercial GCC, the use of unmodified and CTAB- and oleate-modified
calcium carbonate nanoparticles in paper coating improves the properties of
paper. The highest measured paper properties were observed for paper coated
with oleate-modifed nanoparticles, where an increase in smoothness (decrease in
paper roughness) (+23%), brightness (+1.3%), whiteness (+2.8%), and opacity
(+2.3%) and a decrease in air permeability (-26%) was obtained with 25% less
coat weight. The WCA at 10 min was about 112{\deg} for the paper coated with
oleate-modified nanoparticles and 42{\deg} for paper coated with CTAB-modified
nanoparticles compared to 104{\deg} for GCC-coated paper.


title:
DNA Image Pro -- A Tool for Generating Pixel Patterns using DNA Tile
  Assembly

abstract:
  Self-assembly is a process found everywhere in the Nature. In particular, it
is known that DNA self-assembly is Turing universal. Thus one can do arbitrary
computations or build nano-structures using DNA self-assembly. In order to
understand the DNA self-assembly process, many mathematical models have been
proposed in the literature. In particular, abstract Tile Assembly Model (aTAM)
received much attention. In this work, we investigate pixel pattern generation
using aTAM. For a given image, a tile assembly system is given which can
generate the image by self-assembly process. We also consider image blocks with
specific cyclic pixel patterns (uniform shift and non uniform shift) self
assembly. A software, DNA Image Pro, for generating pixel patterns using DNA
tile assembly is also given.


title: Para-Kahler hom-Lie algebras

abstract:
  In this paper, we introduce the notions of pseudo-Riemannian, para-Hermitian
and para- Kahler structures on hom-Lie algebras. In addition, we present the
characterization of these structures. Also, we provide an example including
these structures. We then introduce the phase space of a hom-Lie algebra and
using the hom-left symmetric product, we show that a para-Kahler hom-Lie
algebra gives a phase space and conversely, we can construct a para-Kahler
hom-Lie algebra using a phase space.


title: Nonlinear dynamics of hidden modes in a system with internal symmetry

abstract:
  We consider a discrete dynamical system with internal degrees of freedom
(DOF). Due to the symmetry between the internal DOFs, certain internal modes
cannot be excited by external forcing (in a case of linear interactions) and
thus are considered "hidden". If such a system is weakly asymmetric, the
internal modes remain approximately "hidden" from the external excitation,
given that small damping is taken into account. However, already in the case of
weak cubic nonlinearity, these hidden modes can be excited, even as the exact
symmetry is preserved. This excitation occurs through parametric resonance.
Floquet analysis reveals instability patterns for the explored modes. To
perform this analysis with the required accuracy, we suggest a special method
for obtaining the Fourier series of the unperturbed solution for the nonlinear
normal mode. This method does not require explicit integration of the arising
quadratures. Instead, it employs expansion of the solution at the stage of the
implicit quadrature in terms of Chebyshev polynomials. The emerging implicit
equations are solved by using a fixed-point iteration scheme. Poincar\'{e}
sections help to clarify the correspondence between the loss of stability of
the modes and the global structure of the dynamical flow. In particular, the
conditions for intensive energy exchange in the system are characterized.


title:
A note on quasi generalized CR-lightlike geometry in indefinite nearly
  $\mu$-Sasakian manifold

abstract:
  The concept of quasi generalized CR-lightlike was first introduced by the
authors in [18]. In this paper, we focus on ascreen and co-screen quasi
generalized CR-lightlike submanifolds of indefinite nearly $\mu$-Sasakian
manifold. We prove an existence theorem for minimal ascreen quasi generalized
CR-lightlike submanifolds admitting a metric connection. Classification
theorems on nearly parallel and auto-parallel distributions on a co-screen
quasi generalized CR-lightlike submanifold are also given. Several examples are
also constructed, where necessary, to illustrate the main ideas.


title:
A spectroscopic analysis of a sample of narrow-line Seyfert 1 galaxies
  selected from the Sloan Digital Sky Survey

abstract:
  We revisited the spectroscopic characteristics of narrow-line Seyfert 1
galaxies (NLS1s) by analysing a homogeneous sample of 296 NLS1s at redshift
between 0.028 and 0.345, extracted from the Sloan Digital Sky Survey (SDSS-DR7)
public archive. We confirm that NLS1s are mostly characterized by Balmer lines
with Lorentzian profiles, lower black hole masses and higher Eddington ratios
than classic broad-line Seyfert 1 (BLS1s), but they also appear to be active
galactic nuclei (AGNs) contiguous with BLS1s and sharing with them common
properties. Strong Fe II emission does not seem to be a distinctive property of
NLS1s, as low values of Fe II/H$\beta$ are equally observed in these AGNs. Our
data indicate that Fe II and Ca II kinematics are consistent with the one of
H$\beta$. On the contrary, O I $\lambda$8446 seems to be systematically
narrower and it is likely emitted by gas of the broad-line region more distant
from the ionizing source and showing different physical properties. Finally,
almost all NLS1s of our sample show radial motions of the narrow-line region
highly-ionised gas. The mechanism responsible for this effect is not yet clear,
but there are hints that very fast outflows require high continuum luminosities
(> $10^{44}$ erg/s) or high Eddington ratios (log(L$_{\rm bol}$/L$_{\rm Edd}$)
> -0.1).


title:
Odd Symmetric Tensors, and an Analogue of the Levi-Civita Connection for
  an Odd Symplectic Supermanifold

abstract:
  We consider odd Poisson (odd symplectic) structure on supermanifolds induced
by an odd symmetric rank $2$ (non-degenerate) contravariant tensor field. We
describe the difference between odd Riemannian and odd symplectic structure in
terms of the Cartan prolongation of the corresponding Lie algebras, and
formulate an analogue of the Levi-Civita theorem for an odd symplectic
supermanifold.


title:
Study of a Potential Relationship Between Two Long-Period Comets and
  Rapid Inward Drifting of Aphelion Due to Orbital-Cascade Resonance

abstract:
  We study a potential genetic relationship of comets C/1846 O1 and C/1973 D1,
whose apparent orbital similarity was tested by Kresak (1982) only
statistically, using the Southworth-Hawkins (1963) criterion D. Our orbit
determination for C/1846 O1 shows its period was ~500 yr, ~30 times shorter
than that of C/1973 D1. Formerly unrecognized, this incongruity makes the
objects' common origin less likely. Long-term orbit integration suggests that,
if related, the two comets would have to have separated far away from the Sun
(probably ~700 AU) 21 millennia ago and, unlike C/1973 D1, C/1846 O1 would have
to have been subjected to a complex orbital evolution. Given the chance of
encountering Jupiter to ~0.6 AU some 400 days after perihelion, C/1846 O1 and
C/1973 D1 may have been perturbed, during their return in the 15th millennium
BCE, into orbits that were, respectively, smaller and larger than was the
parent's, with a net difference of more than 0.002 (AU)^{-1} in 1/a. Whereas
C/1973 D1 was on the way to its 1973 perihelion, C/1846 O1 should have been
subjected to recurring encounters with Jupiter, during which the orbital period
continued to shorten by integral multiples of the Jovian orbital period, a
process called high-order orbital-cascade resonance. While the integrated
perturbation effect of C/1846 O1 by Jupiter does not appear to reduce the
comet's orbital period to below ~1200 yr by the mid-19th century, we find that
orbital-cascade resonance offers an attractive mechanism for rapid inward
drifting of aphelion especially among dynamically new comets.


title:
Gravitationally induced particle production and its impact on structure
  formation

abstract:
  In this paper we investigate the influence of a continuous particles creation
processes on the linear and nonlinear matter clustering, and its consequences
on the weak lensing effect induced by structure formation. We study the line of
sight behavior of the contribution to the bispectrum signal at a given angular
multipole $l$, showing that the scale where the nonlinear growth overcomes the
linear effect depends strongly of particles creation rate.


title:
The Additive Structure of Cartesian Products Spanning Few Distinct
  Distances

abstract:
  Guth and Katz proved that any point set $\mathcal P$ in the plane determines
$\Omega(|\mathcal P|/\log|\mathcal P|)$ distinct distances. We show that when
near to this lower bound, a point set $\mathcal P$ of the form $A\times A$ must
satisfy $|A-A|\ll |A|^{2-1/8}$.


title:
A Survey about Prediction-Based Data Reduction in Wireless Sensor
  Networks

abstract:
  One of the main characteristics of Wireless Sensor Networks (WSNs) is the
constrained energy resources of their wireless sensor nodes. Although this
issue has been addressed in several works and got a lot of attention within the
years, the most recent advances pointed out that the energy harvesting and
wireless charging techniques may offer means to overcome such a limitation.
Consequently, an issue that had been put in second place, now emerges: the low
availability of spectrum resources. Because of it, the incorporation of the
WSNs into the Internet of Things and the exponential growth of the latter may
be hindered if no control over the data generation is taken. Alternatively,
part of the sensed data can be predicted without triggering transmissions and
congesting the wireless medium. In this work, we analyze and categorize
existing prediction-based data reduction mechanisms that have been designed for
WSNs. Our main contribution is a systematic procedure for selecting a scheme to
make predictions in WSNs, based on WSNs' constraints, characteristics of
prediction methods and monitored data. Finally, we conclude the paper with a
discussion about future challenges and open research directions in the use of
prediction methods to support the WSNs' growth.


title: Subgroups of 3-factor direct products

abstract:
  Extending Goursat's Lemma we investigate the structure of subdirect products
of 3-factor direct products. We give several example constructions and then
provide a structure theorem showing that every such group is essentially
obtained by a combination of the constructions. The central observation in this
structure theorem is that the dependencies among the group elements in the
subdirect product that involve all three factors are of Abelian nature. In the
spirit of Goursat's Lemma, for two special cases, we derive correspondence
theorems between data obtained from the subgroup lattices of the three factors
(as well as isomorphism between arising factor groups) and the subdirect
products. Using our results we derive an explicit formula to count the number
of subdirect products of the direct product of three symmetric groups.


title: Liquid Information Flow Control

abstract:
  We present Lifty, a domain-specific language for data-centric applications
that manipulate sensitive data. A Lifty programmer annotates the sources of
sensitive data with declarative security policies, and the language statically
and automatically verifies that the application handles the data according to
the policies. Moreover, if verification fails, Lifty suggests a provably
correct repair, thereby easing the programmer burden of implementing policy
enforcing code throughout the application.
  The main insight behind Lifty is to encode information flow control using
liquid types, an expressive yet decidable type system. Liquid types enable
fully automatic checking of complex, data dependent policies, and power our
repair mechanism via type-driven error localization and patch synthesis. Our
experience using Lifty to implement three case studies from the literature
shows that (1) the Lifty policy language is sufficiently expressive to specify
many real-world policies, (2) the Lifty type checker is able to verify secure
programs and find leaks in insecure programs quickly, and (3) even if the
programmer leaves out all policy enforcing code, the Lifty repair engine is
able to patch all leaks automatically within a reasonable time.


title:
Unresolved versus resolved: testing the validity of young simple stellar
  population models with VLT/MUSE observations of NGC 3603

abstract:
  CONTEXT. Stellar populations are the building blocks of galaxies including
the Milky Way. The majority, if not all extragalactic studies are entangled
with the use of stellar population models given the unresolved nature of their
observation. Extragalactic systems contain multiple stellar populations with
complex star formation histories. However, their study is mainly based upon the
principles of simple stellar populations (SSP). Hence, it is critical to
examine the validity of SSP models. AIMS. This work aims to empirically test
the validity of SSP models. This is done by comparing SSP models against
observations of spatially resolved young stellar population in the
determination of its physical properties, i.e. age and metallicity. METHODS.
Integral field spectroscopy of a young stellar cluster in the Milky Way, NGC
3603, is used to study the properties of the cluster both as a resolved and
unresolved stellar population. The unresolved stellar population is analysed
using the H$\alpha$ equivalent width as an age indicator, and the ratio of
strong emission lines to infer metallicity. In addition, spectral energy
distribution (SED) fitting using STARLIGHT, is used to infer these properties
from the integrated spectrum. Independently, the resolved stellar population is
analysed using the color-magnitude diagram (CMD) for age and metallicity
determination. As the SSP model represents the unresolved stellar population,
the derived age and metallicity are put to test whether they agree with those
derived from resolved stars. RESULTS. The age and metallicity estimate of NGC
3603 derived from integrated spectroscopy are confirmed to be within the range
of those derived from the CMD of the resolved stellar population, including
other estimates found in the literature. The result from this pilot study
supports the reliability of SSP models for studying unresolved young stellar
populations.


title: Higgs mass from neutrino-messenger mixing

abstract:
  The discovery of the Higgs particle at 125 GeV has put strong constraints on
minimal messenger models of gauge mediation, pushing the stop masses into the
multi-TeV regime. Extensions of these models with matter-messenger mixing terms
have been proposed to generate a large trilinear parameter, $A_t$, relaxing
these constraints. The detailed survey of these models
\cite{Byakti:2013ti,Evans:2013kxa} so far considered messenger mixings with
only MSSM superfields. In the present work, we extend the survey to MSSM with
inverse-seesaw mechanism. The neutrino-sneutrino corrections to the Higgs mass
in the inverse seesaw model are not significant in the minimal gauge mediation
model, unless one considers messenger-matter interaction terms. We classify all
possible models with messenger-matter interactions and perform thorough
numerical analysis to find out the promising models. We found that out of the
17 possible models 9 of them can lead to Higgs mass within the observed value
without raising the sfermion masses significantly. The successful models have
stop masses $\sim $1.5 TeV with small or negligible mixing and yet a light CP
even Higgs at 125 GeV.


title: Development of dual-polarization LEKIDs for CMB observations

abstract:
  We discuss the design considerations and initial measurements from arrays of
dual-polarization, lumped element kinetic inductance detectors (LEKIDs)
nominally designed for cosmic microwave background (CMB) studies. The detectors
are horn-coupled, and each array element contains two single-polarization
LEKIDs, which are made from thin-film aluminum and optimized for a single
spectral band centered on 150 GHz. We are developing two array architectures,
one based on 160 micron thick silicon wafers and the other based on
silicon-on-insulator (SOI) wafers with a 30 micron thick device layer. The
20-element test arrays (40 LEKIDs) are characterized with both a
linearly-polarized electronic millimeter wave source and a thermal source. We
present initial measurements including the noise spectra, noise-equivalent
temperature, and responsivity. We discuss future testing and further design
optimizations to be implemented.


title:
Theory for Spin Selective Andreev Reflection in Vortex Core of
  Topological Superconductor: Majorana Zero Modes on Spherical Surface and
  Application to Spin Polarized Scanning Tunneling Microscope Probe

abstract:
  Majorana zero modes (MZMs) have been predicted to exist in the topological
insulator (TI)/superconductor (SC) heterostructure. Recent spin polarized
scanning tunneling microscope (STM) experiment$^{1}$ has observed
spin-polarization dependence of the zero bias differential tunneling
conductance at the center of vortex core, which may be attributed to the spin
selective Andreev reflection, a novel property of the MZMs theoretically
predicted in 1-dimensional nanowire$^{2}$. Here we consider a helical electron
system described by a Rashba spin orbit coupling Hamiltonian on a spherical
surface with a s-wave superconducting pairing due to proximity effect. We
examine in-gap excitations of a pair of vortices with one at the north pole and
the other at the south pole. While the MZM is not a spin eigenstate, the spin
wavefunction of the MZM at the center of the vortex core, r = 0, is parallel to
the magnetic field, and the local Andreev reflection of the MZM is spin
selective, namely occurs only when the STM tip has the spin polarization
parallel to the magnetic field, similar to the case in 1-dimensional nanowire2.
The total local differential tunneling conductance consists of the normal term
proportional to the local density of states and an additional term arising from
the Andreev reflection. We also discuss the finite size effect, for which the
MZM at the north pole is hybridized with the MZM at the south pole. We apply
our theory to examine the recently reported spin-polarized STM experiments and
show good agreement with the experiments.


title:
Side-Channel Attack Resilience through Route Randomisation in Secure
  Real-Time Networks-on-Chip

abstract:
  Security can be seen as an optimisation objective in NoC resource management,
and as such poses trade-offs against other objectives such as real-time
schedulability. In this paper, we show how to increase NoC resilience against a
concrete type of security attack, named side-channel attack, which exploit the
correlation between specific non-functional properties (such as packet
latencies and routes, in the case of NoCs) to infer the functional behaviour of
secure applications. For instance, the transmission of a packet over a given
link of the NoC may hint on a cache miss, which can be used by an attacker to
guess specific parts of a secret cryptographic key, effectively weakening it.
  We therefore propose packet route randomisation as a mechanism to increase
NoC resilience against side-channel attacks, focusing specifically on the
potential impact of such an approach upon hard real-time systems, where
schedulability is a vital design requirement. Using an evolutionary
optimisation approach, we show how to effectively apply route randomisation in
such a way that it can increase NoC security while controlling its impact on
hard real-time performance guarantees. Extensive experimental evidence based on
analytical and simulation models supports our findings.


title:
The explicit Plancherel formula on the line budle of ${\rm SL}(n+1,
  {\mathbb R})/{\rm S}({\rm GL}(1, {\mathbb R})\times {\rm GL}(n, {\mathbb
  R}))$

abstract:
  The purpose of this paper is to study the Plancherel formula for the spaces
of $L^2$-sections of the line bundles over the pseudo-Riemannian space $G/H$,
where $G={\rm SL}(n+1, {\mathbb R})$ and $H={\rm S}({\rm GL}(1, {\mathbb
R})\times {\rm GL}(n, {\mathbb R}))$. The formula is given in an explicit form
by means of spherical distributions associated with the character
$\chi_{_\lambda}$ of the subgroup $H$.


title: Individual ergodic theorems for semifinite von Neumann algebras

abstract:
  It is known that, for a positive Dunford-Schwartz operator in a
noncommutative $L^p-$space, $1\leq p<\infty$ or, more generally, in a
noncommutative Orlicz space with order continuous norm, the corresponding
ergodic averages converge bilaterally almost uniformly. We show that these
averages converge almost uniformly in each noncommutative symmetric space $E$
such that $\mu_t(x) \to 0$ as $t \to 0$ for every $x \in E$, where $\mu_t(x)$
is a non-increasing rearrangement of $x$. Noncommutative Dunford-Schwartz-type
multiparameter ergodic theorems are studied. A wide range of noncommutative
symmetric spaces for which Dunford-Schwartz-type individual ergodic theorems
hold is outlined. Also, almost uniform convergence in noncommutative
Wiener-Wintner theorem is proved.


title:
Renormalization-group flow of the effective action of cosmological
  large-scale structures

abstract:
  Following an approach of Matarrese and Pietroni, we derive the functional
renormalization group (RG) flow of the effective action of cosmological
large-scale structures. Perturbative solutions of this RG flow equation are
shown to be consistent with standard cosmological perturbation theory.
Non-perturbative approximate solutions can be obtained by truncating the a
priori infinite set of possible effective actions to a finite subspace. Using
for the truncated effective action a form dictated by dissipative fluid
dynamics, we derive RG flow equations for the scale dependence of the effective
viscosity and sound velocity of non-interacting dark matter, and we solve them
numerically. Physically, the effective viscosity and sound velocity account for
the interactions of long-wavelength fluctuations with the spectrum of
smaller-scale perturbations. We find that the RG flow exhibits an attractor
behaviour in the IR that significantly reduces the dependence of the effective
viscosity and sound velocity on the input values at the UV scale. This allows
for a self-contained computation of matter and velocity power spectra for which
the sensitivity to UV modes is under control.


title: The infinite bi-Lanczos method for nonlinear eigenvalue problems

abstract:
  We propose a two-sided Lanczos method for the nonlinear eigenvalue problem
(NEP). This two-sided approach provides approximations to both the right and
left eigenvectors of the eigenvalues of interest. The method implicitly works
with matrices and vectors with infinite size, but because particular (starting)
vectors are used, all computations can be carried out efficiently with finite
matrices and vectors. We specifically introduce a new way to represent infinite
vectors that span the subspace corresponding to the conjugate transpose
operation for approximating the left eigenvectors. Furthermore, we show that
also in this infinite-dimensional interpretation the short recurrences inherent
to the Lanczos procedure offer an efficient algorithm regarding both the
computational cost and the storage.


title: Coupling proofs are probabilistic product programs

abstract:
  Couplings are a powerful mathematical tool for reasoning about pairs of
probabilistic processes. Recent developments in formal verification identify a
close connection between couplings and pRHL, a relational program logic
motivated by applications to provable security, enabling formal construction of
couplings from the probability theory literature. However, existing work using
pRHL merely shows existence of a coupling and does not give a way to prove
quantitative properties about the coupling, which are need to reason about
mixing and convergence of probabilistic processes. Furthermore, pRHL is
inherently incomplete, and is not able to capture some advanced forms of
couplings such as shift couplings. We address both problems as follows.
  First, we define an extension of pRHL, called xpRHL, which explicitly
constructs the coupling in a pRHL derivation in the form of a probabilistic
product program that simulates two correlated runs of the original program.
Existing verification tools for probabilistic programs can then be directly
applied to the probabilistic product to prove quantitative properties of the
coupling. Second, we equip pRHL with a new rule for while loops, where
reasoning can freely mix synchronized and unsynchronized loop iterations. Our
proof rule can capture examples of shift couplings, and the logic is relatively
complete for deterministic programs.
  We show soundness of xpRHL and use it to analyze two classes of examples.
First, we verify rapid mixing using different tools from coupling: standard
coupling, shift coupling, and path coupling, a compositional principle for
combining local couplings into a global coupling. Second, we verify
(approximate) equivalence between a source and an optimized program for several
instances of loop optimizations from the literature.


title: Incomplete Pivoted QR-based Dimensionality Reduction

abstract:
  High-dimensional big data appears in many research fields such as image
recognition, biology and collaborative filtering. Often, the exploration of
such data by classic algorithms is encountered with difficulties due to `curse
of dimensionality' phenomenon. Therefore, dimensionality reduction methods are
applied to the data prior to its analysis. Many of these methods are based on
principal components analysis, which is statistically driven, namely they map
the data into a low-dimension subspace that preserves significant statistical
properties of the high-dimensional data. As a consequence, such methods do not
directly address the geometry of the data, reflected by the mutual distances
between multidimensional data point. Thus, operations such as classification,
anomaly detection or other machine learning tasks may be affected.
  This work provides a dictionary-based framework for geometrically driven data
analysis that includes dimensionality reduction, out-of-sample extension and
anomaly detection. It embeds high-dimensional data in a low-dimensional
subspace. This embedding preserves the original high-dimensional geometry of
the data up to a user-defined distortion rate. In addition, it identifies a
subset of landmark data points that constitute a dictionary for the analyzed
dataset. The dictionary enables to have a natural extension of the
low-dimensional embedding to out-of-sample data points, which gives rise to a
distortion-based criterion for anomaly detection. The suggested method is
demonstrated on synthetic and real-world datasets and achieves good results for
classification, anomaly detection and out-of-sample tasks.


title:
Direct measurement of lensing amplification in Abell S1063 using a
  strongly lensed high redshift HII Galaxy

abstract:
  ID11 is an actively star forming extremely compact galaxy and Ly alpha
emitter at z=3.117 that is gravitationally magnified by a factor of ~17 by the
cluster of galaxies Hubble Frontier Fields AS1063. Its observed properties
resemble those of low luminosity HII galaxies or Giant HII regions like
30-Doradus in the LMC.
  Using the tight correlation correlation between the Balmer-line luminosities
and the width of the emission lines (typically L(Hbeta)-sigma(Hbeta)) valid for
HII galaxies and Giant HII regions to estimate its total luminosity, we are
able to measure the lensing amplification of ID11. We obtain an amplification
of 23 +- 11 similar within errors to the value of ~17 estimated or predicted by
the best lensing models of the massive cluster Abell S1063.
  We also compiled from the literature luminosities and velocity dispersions
for a set of lensed compact starforming regions. There is more scatter in the
L-sigma correlation for these lensed systems but on the whole the results tend
to support the lensing models estimates of the magnification.
  Our result indicates that the amplification can be independently measured
using the L-sigma relation in lensed Giant HII regions or HII galaxies. It also
supports the suggestion, even if lensing model dependent, that the L-sigma
relation is valid for low luminosity high-z objects. Ad-hoc observations of
lensed starforming systems are required to accurately determine the lensing
amplification.


title:
Symmetric duality for left and right Riemann-Liouville and Caputo
  fractional differences

abstract:
  A discrete version of the symmetric duality of Caputo-Torres, to relate left
and right Riemann-Liouville and Caputo fractional differences, is considered.
As a corollary, we provide an evidence to the fact that in case of right
fractional differences, one has to mix between nabla and delta operators. As an
application, we derive right fractional summation by parts formulas and left
fractional difference Euler-Lagrange equations for discrete fractional
variational problems whose Lagrangians depend on right fractional differences.


title: Null-stream pointing with pulsar timing arrays

abstract:
  Locating sources on the sky is one of the largest challenges in gravitational
wave astronomy, owing to the omni-directional nature of gravitational wave
detection techniques, and the often intrinsically weak signals being observed.
Ground-based detectors can address the pointing problem by observing with a
network of detectors, effectively triangulating signal locations by observing
the arrival times across the network. Space-based detectors will observe
long-lived sources that persist while the detector moves relative to their
location on the sky, using Doppler shifts of the signal to locate the sky
position. While these methods improve the pointing capability of a detector or
network, the angular resolution is still coarse compared to the standards one
expects from electromagnetic astronomy. Another technique that can be used for
sky localization is null-stream pointing. In the case where multiple
independent data streams exist, a single astrophysical source of gravitational
waves will appear in each of the data streams. Taking the signals from multiple
detectors in linear combination with each other, one finds there is a two
parameter family of coefficients that effectively null the gravitational wave
signal; those two parameters are the angles that define the sky location of the
source. This technique has been demonstrated for a network of ground-based
interferometric observatories, and for 6-link space interferometers. This paper
derives and extends the null-stream pointing method to the unique case of
pulsar timing residuals. The basic method is derived and demonstrated, and the
necessity of using the method with multiple sub-arrays of pulsars in the pulsar
timing array network is considered.


title:
ROAM: a Radial-basis-function Optimization Approximation Method for
  diagnosing the three-dimensional coronal magnetic field

abstract:
  The Coronal Multichannel Polarimeter (CoMP) routinely performs coronal
polarimetric measurements using the Fe XIII 10747 $\AA$ and 10798 $\AA$ lines,
which are sensitive to the coronal magnetic field. However, inverting such
polarimetric measurements into magnetic field data is a difficult task because
the corona is optically thin at these wavelengths and the observed signal is
therefore the integrated emission of all the plasma along the line of sight. To
overcome this difficulty, we take on a new approach that combines a
parameterized 3D magnetic field model with forward modeling of the polarization
signal. For that purpose, we develop a new, fast and efficient, optimization
method for model-data fitting: the Radial-basis-functions Optimization
Approximation Method (ROAM). Model-data fitting is achieved by optimizing a
user-specified log-likelihood function that quantifies the differences between
the observed polarization signal and its synthetic/predicted analogue. Speed
and efficiency are obtained by combining sparse evaluation of the magnetic
model with radial-basis-function (RBF) decomposition of the log-likelihood
function. The RBF decomposition provides an analytical expression for the
log-likelihood function that is used to inexpensively estimate the set of
parameter values optimizing it. We test and validate ROAM on a synthetic test
bed of a coronal magnetic flux rope and show that it performs well with a
significantly sparse sample of the parameter space. We conclude that our
optimization method is well-suited for fast and efficient model-data fitting
and can be exploited for converting coronal polarimetric measurements, such as
the ones provided by CoMP, into coronal magnetic field data.


title:
Holomorphic Yukawa Couplings for Complete Intersection Calabi-Yau
  Manifolds

abstract:
  We develop methods to compute holomorphic Yukawa couplings for heterotic
compactifications on complete intersection Calabi-Yau manifolds, generalising
results of an earlier paper for Calabi-Yau hypersurfaces. Our methods are based
on constructing the required bundle-valued forms explicitly and evaluating the
relevant integrals over the projective ambient space. We also show how our
approach relates to an earlier, algebraic one to calculate the holomorphic
Yukawa couplings. A vanishing theorem, which we prove, implies that certain
Yukawa couplings allowed by low-energy symmetries are zero due to topological
reasons. To illustrate our methods, we calculate Yukawa couplings for
SU(5)-based standard models on a co-dimension two complete intersection
manifold.


title:
A refined mass distribution of the cluster MACS J0416.1$-$2403 from a
  new large set of spectroscopic multiply lensed sources

abstract:
  We report the spectroscopic confirmation of 22 new multiply lensed sources
behind the Hubble Frontier Field (HFF) galaxy cluster MACS~J0416.1$-$2403 (MACS
0416), using archival data from the Multi Unit Spectroscopic Explorer (MUSE) on
the VLT. Combining with previous spectroscopic measurements of 15 other
multiply imaged sources, we obtain a sample of 102 secure multiple images with
measured redshifts, the largest to date in a single strong lensing system. The
newly confirmed sources are largely low-luminosity Lyman-$\alpha$ emitters with
redshift in the range [3.08-6.15]. With such a large number of secure
constraints, and a significantly improved sample of galaxy members in the
cluster core, we have improved our previous strong lensing model and obtained a
robust determination of the projected total mass distribution of MACS 0416. We
find evidence of three cored dark-matter halos, adding to the known complexity
of this merging system. The total mass density profile, as well as the sub-halo
population, are found in good agreement with previous works. We update and make
public the redshift catalog of MACS 0416 from our previous spectroscopic
campaign with the new MUSE redshifts. We also release lensing maps
(convergence, shear, magnification) in the standard HFF format.


title: LazySVD: Even Faster SVD Decomposition Yet Without Agonizing Pain

abstract:
  We study $k$-SVD that is to obtain the first $k$ singular vectors of a matrix
$A$. Recently, a few breakthroughs have been discovered on $k$-SVD: Musco and
Musco [1] proved the first gap-free convergence result using the block Krylov
method, Shamir [2] discovered the first variance-reduction stochastic method,
and Bhojanapalli et al. [3] provided the fastest $O(\mathsf{nnz}(A) +
\mathsf{poly}(1/\varepsilon))$-time algorithm using alternating minimization.
  In this paper, we put forward a new and simple LazySVD framework to improve
the above breakthroughs. This framework leads to a faster gap-free method
outperforming [1], and the first accelerated and stochastic method
outperforming [2]. In the $O(\mathsf{nnz}(A) + \mathsf{poly}(1/\varepsilon))$
running-time regime, LazySVD outperforms [3] in certain parameter regimes
without even using alternating minimization.


title:
A Representation Theory Perspective on Simultaneous Alignment and
  Classification

abstract:
  One of the difficulties in 3D reconstruction of molecules from images in
single particle Cryo-Electron Microscopy (Cryo-EM), in addition to high levels
of noise and unknown image orientations, is heterogeneity in samples: in many
cases, the samples contain a mixture of molecules, or multiple conformations of
one molecule. Many algorithms for the reconstruction of molecules from images
in heterogeneous Cryo-EM experiments are based on iterative approximations of
the molecules in a non-convex optimization that is prone to reaching suboptimal
local minima. Other algorithms require an alignment in order to perform
classification, or vice versa. The recently introduced Non-Unique Games
framework provides a representation theoretic approach to studying problems of
alignment over compact groups, and offers convex relaxations for alignment
problems which are formulated as semidefinite programs (SDPs) with certificates
of global optimality under certain circumstances. In this manuscript, we
propose to extend Non-Unique Games to the problem of simultaneous alignment and
classification with the goal of simultaneously classifying Cryo-EM images and
aligning them within their respective classes. Our proposed approach can also
be extended to the case of continuous heterogeneity.


title: Generalized Recurrence and the Nonwandering Set for Products

abstract:
  For continuous maps of compact metric spaces $f:X\to X$ and $g:Y\to Y$ and
for various notions of topological recurrence, we study the relationship
between recurrence for $f$ and $g$ and recurrence for the product map $f\times
g:X\times Y \to X\times Y$. For the generalized recurrent set $GR$, we see that
$GR(f\times g)=GR(f)\times GR(g)$. For the nonwandering set $NW$, we see that
$NW(f\times g)\subset NW(f)\times NW(g)$ and give necessary and sufficient
conditions on $f$ for equality for every $g$. We also consider product
recurrence for the chain recurrent set, the strong chain recurrent set, and the
Ma\~n\'e set.


title: A L\^e-Greuel type formula for the image Milnor number

abstract:
  Let $f:(\mathbb{C}^n,0)\rightarrow (\mathbb{C}^{n+1},0)$ be a corank 1
finitely determined map germ. For a generic linear form
$p:(\mathbb{C}^{n+1},0)\to(\mathbb{C},0)$ we denote by
$g:(\mathbb{C}^{n-1},0)\rightarrow (\mathbb{C}^{n},0)$ the transverse slice of
$f$ with respect to $p$. We prove that the sum of the image Milnor numbers
$\mu_I(f)+\mu_I(g)$ is equal to the number of critical points of the stratified
Morse function $p|_{X_s}:X_s\to\mathbb{C}$, where $X_s$ is the disentanglement
of $f$ (i.e., the image of a stabilisation $f_s$ of $f$).


title: Pseudo-Centroid Clustering

abstract:
  Pseudo-Centroid Clustering replaces the traditional concept of a centroid
expressed as a center of gravity with the notion of a pseudo-centroid (or a
coordinate free centroid) which has the advantage of applying to clustering
problems where points do not have numerical coordinates (or categorical
coordinates that are translated into numerical form). Such problems, for which
classical centroids do not exist, are particularly important in social
sciences, marketing, psychology and economics, where distances are not computed
from vector coordinates but rather are expressed in terms of characteristics
such as affinity relationships, psychological preferences, advertising
responses, polling data, market interactions and so forth, where distances,
broadly conceived, measure the similarity (or dissimilarity) of
characteristics, functions or structures.
  We formulate a K-PC algorithm analogous to a K-Means algorithm, and identify
two key types of pseudo-centroids, MinMax centroids and (weighted) MinSum
centroids, and describe how they respectively give rise to a K-MinMax algorithm
and a K-MinSum algorithm which are analogous to a K-Means algorithm. The K-PC
algorithms are able to take advantage of problem structure to identify special
diversity-based and intensity-based starting methods to generate initial
pseudo-centroids and associated clusters, accompanied by theorems for the
intensity-based methods that establish their ability to obtain best clusters of
a selected size from the points available at each stage of construction. We
also introduce a Regret-Threshold PC algorithm that modifies the K-PC algorithm
together with an associated diversification method and a new criterion for
evaluating the quality of a collection of clusters.


title: Event-based, 6-DOF Camera Tracking from Photometric Depth Maps

abstract:
  Event cameras are bio-inspired vision sensors that output pixel-level
brightness changes instead of standard intensity frames. These cameras do not
suffer from motion blur and have a very high dynamic range, which enables them
to provide reliable visual information during high-speed motions or in scenes
characterized by high dynamic range. These features, along with a very low
power consumption, make event cameras an ideal complement to standard cameras
for VR/AR and video game applications. With these applications in mind, this
paper tackles the problem of accurate, low-latency tracking of an event camera
from an existing photometric depth map (i.e., intensity plus depth information)
built via classic dense reconstruction pipelines. Our approach tracks the 6-DOF
pose of the event camera upon the arrival of each event, thus virtually
eliminating latency. We successfully evaluate the method in both indoor and
outdoor scenes and show that---because of the technological advantages of the
event camera---our pipeline works in scenes characterized by high-speed motion,
which are still unaccessible to standard cameras.


title: Computation of Heavy Quarkonium Spectrum in Perturbative QCD

abstract:
  Non-relativistic bound state theories for QED and QCD have become fairly
mature and amenable to a textbook-level understanding and computation. In this
talk we give an introductory review of the following subjects related to the
recent computation of the heavy quarkonium spectrum using perturbative QCD: (1)
Technological developments in higher-order computation, (2) Physics
predictions, (3) Challenge towards analytic evaluation of the 3-loop static QCD
potential.


title: Jucys-Murphy elements for Soergel bimodules

abstract:
  We produce Jucys-Murphy elements for the diagrammatical category of Soergel
bimodules associated with general Coxeter groups, and use them to diagonalize
the bilinear form on the cell modules. This gives rise to an expression for the
determinant of the forms and Jantzen type sum formulas.


title: Cop-Win Graphs: Optimal Strategies and Corner Rank

abstract:
  We investigate the game of cops and robber, played on a finite graph, between
one cop and one robber. If the cop can force a win on a graph, the graph is
called cop-win. We describe a procedure we call corner ranking, performed on a
graph, which assigns a positive integer or $\infty$ to each vertex. We give a
characterization of cop-win in terms of corner rank and also show that the
well-known characterization of cop-win via dismantling orderings follows from
our work. From the corner rank we can determine the capture time of a graph,
i.e. the number of turns the cop needs to win. We describe a class of optimal
cop strategies we call Lower Way strategies, and a class of optimal robber
strategies we call Higher Way strategies. Roughly speaking, in a Lower Way
strategy, the cop pushes the robber down to lower ranked vertices, while in a
Higher Way strategy, the robber moves to a highest rank vertex that is "safe."
While interesting in their own right, the strategies are themselves tools in
our proofs. We investigate various properties of the Lower Way strategies.


title: The automorphism group of a rigid affine variety

abstract:
  An irreducible algebraic variety $X$ is rigid if it admits no nontrivial
action of the additive group of the ground field. We prove that the
automorphism group $\text{Aut}(X)$ of a rigid affine variety contains a unique
maximal torus $\mathbb{T}$. If the grading on the algebra of regular functions
$\mathbb{K}[X]$ defined by the action of $\mathbb{T}$ is pointed, the group
$\text{Aut}(X)$ is a finite extension of $\mathbb{T}$. As an application, we
describe the automorphism group of a rigid trinomial affine hypersurface and
find all isomorphisms between such hypersurfaces.


title: Infinitesimal moduli of G2 holonomy manifolds with instanton bundles

abstract:
  We describe the infinitesimal moduli space of pairs $(Y, V)$ where $Y$ is a
manifold with $G_2$ holonomy, and $V$ is a vector bundle on $Y$ with an
instanton connection. These structures arise in connection to the moduli space
of heterotic string compactifications on compact and non-compact seven
dimensional spaces, e.g. domain walls. Employing the canonical $G_2$ cohomology
developed by Reyes-Carri\'on and Fern\'andez and Ugarte, we show that the
moduli space decomposes into the sum of the bundle moduli
$H^1_{\check{d}_A}(Y,\mathrm{End}(V))$ plus the moduli of the $G_2$ structure
preserving the instanton condition. The latter piece is contained in
$H^1_{\check{d}_\theta}(Y,TY)$, and is given by the kernel of a map
${\cal\check F}$ which generalises the concept of the Atiyah map for
holomorphic bundles on complex manifolds to the case at hand. In fact, the map
${\cal\check F}$ is given in terms of the curvature of the bundle and maps
$H^1_{\check{d}_\theta}(Y,TY)$ into $H^2_{\check{d}_A}(Y,\mathrm{End}(V))$, and
moreover can be used to define a cohomology on an extension bundle of $TY$ by
$\mathrm{End}(V)$. We comment further on the resemblance with the holomorphic
Atiyah algebroid and connect the story to physics, in particular to heterotic
compactifications on $(Y,V)$ when $\alpha'=0$.


title: Recurrent Highway Networks

abstract:
  Many sequential processing tasks require complex nonlinear transition
functions from one step to the next. However, recurrent neural networks with
'deep' transition functions remain difficult to train, even when using Long
Short-Term Memory (LSTM) networks. We introduce a novel theoretical analysis of
recurrent networks based on Gersgorin's circle theorem that illuminates several
modeling and optimization issues and improves our understanding of the LSTM
cell. Based on this analysis we propose Recurrent Highway Networks, which
extend the LSTM architecture to allow step-to-step transition depths larger
than one. Several language modeling experiments demonstrate that the proposed
architecture results in powerful and efficient models. On the Penn Treebank
corpus, solely increasing the transition depth from 1 to 10 improves word-level
perplexity from 90.6 to 65.4 using the same number of parameters. On the larger
Wikipedia datasets for character prediction (text8 and enwik8), RHNs outperform
all previous results and achieve an entropy of 1.27 bits per character.


title: Nystrom Method for Approximating the GMM Kernel

abstract:
  The GMM (generalized min-max) kernel was recently proposed (Li, 2016) as a
measure of data similarity and was demonstrated effective in machine learning
tasks. In order to use the GMM kernel for large-scale datasets, the prior work
resorted to the (generalized) consistent weighted sampling (GCWS) to convert
the GMM kernel to linear kernel. We call this approach as ``GMM-GCWS''.
  In the machine learning literature, there is a popular algorithm which we
call ``RBF-RFF''. That is, one can use the ``random Fourier features'' (RFF) to
convert the ``radial basis function'' (RBF) kernel to linear kernel. It was
empirically shown in (Li, 2016) that RBF-RFF typically requires substantially
more samples than GMM-GCWS in order to achieve comparable accuracies.
  The Nystrom method is a general tool for computing nonlinear kernels, which
again converts nonlinear kernels into linear kernels. We apply the Nystrom
method for approximating the GMM kernel, a strategy which we name as
``GMM-NYS''. In this study, our extensive experiments on a set of fairly large
datasets confirm that GMM-NYS is also a strong competitor of RBF-RFF.


title: End-to-end training of object class detectors for mean average precision

abstract:
  We present a method for training CNN-based object class detectors directly
using mean average precision (mAP) as the training loss, in a truly end-to-end
fashion that includes non-maximum suppression (NMS) at training time. This
contrasts with the traditional approach of training a CNN for a window
classification loss, then applying NMS only at test time, when mAP is used as
the evaluation metric in place of classification accuracy. However, mAP
following NMS forms a piecewise-constant structured loss over thousands of
windows, with gradients that do not convey useful information for gradient
descent. Hence, we define new, general gradient-like quantities for piecewise
constant functions, which have wide applicability. We describe how to calculate
these efficiently for mAP following NMS, enabling to train a detector based on
Fast R-CNN directly for mAP. This model achieves equivalent performance to the
standard Fast R-CNN on the PASCAL VOC 2007 and 2012 datasets, while being
conceptually more appealing as the very same model and loss are used at both
training and test time.


title:
Superconducting properties and hydrostatic pressure effect on ABi3
  (A=Ba,Sr) single crystals

abstract:
  We report on the crystal growth and characterization of ABi3 (A=Ba,Sr)
superconductors. Single crystals of both compounds were grown by the self-flux
technique. BaBi3 crystallized in a tetragonal structure with space group P4/mmm
and SrBi3 in a cubic structure with space group Pm-3m. Superconductivity at Tc
= 6.0 K for BaBi3 and Tc = 5.6 K for SrBi3 have been confirmed through dc
magnetic susceptibility and electrical transport measurements. The dc magnetic
susceptibility under hydrostatic pressure shows a positive pressure coefficient
of dTc/dP = 1.22 K/GPa for BaBi3 and a negative pressure coefficient of dTc/dP
= -0.48 K/GPa for SrBi3. The normal state electrical resistivity shows that
both compounds are highly metallic in nature. The upper critical fields Hc2
evaluated by resistivity under magnetic fields $\rho(T,H)$ are 22 kOe for BaBi3
and 2.9 kOe for SrBi3. A specific heat jump of $\Delta Ce/\gamma Tc = 1.05$
suggests weak coupling superconductivity in BaBi3, whereas $\Delta Ce/\gamma Tc
= 2.08$ for SrBi3 is higher than the BCS theory value of 1.43, indicating a
strong coupling superconductor.


title:
Classical and quantum cosmology with two perfect fluids: stiff matter
  and radiation

abstract:
  In this work the homogeneous and isotropic Universe of
Friedmann-Robertson-Walker is studied in the presence of two fluids: stiff
matter and radiation described by the Schutz's formalism. We obtain to the
classic case the behaviour of the scale factor of the universe. For the quantum
case the wave packets are constructed and the wave function of the universe is
found.


title:
SAT-based Distributed Reactive Control Protocol Synthesis for Boolean
  Networks

abstract:
  This paper considers the synthesis of distributed reactive control protocols
for a Boolean network in a distributed manner. We start with a directed acyclic
graph representing a network of Boolean subsystems and a global contract, given
as an assumption-guarantee pair. Assumption captures the environment behavior,
and guarantee is the requirements to be satisfied by the system. Local
assumption-guarantee contracts, together with local control protocols ensuring
these local contracts, are computed recursively for each subsystem based on the
partial order structure induced by the directed acyclic graph. By construction,
implementing these local control protocols together guarantees the satisfaction
of the global assumption-guarantee contract. Moreover, local control protocol
synthesis reduces to quantified satisfiability (QSAT) problems in this setting.
We also discuss structural properties of the network that affect the
completeness of the proposed algorithm. As an application, we show how an
aircraft electric power system can be represented as a Boolean network, and we
synthesize distributed control protocols from a global assumption-guarantee
contract. The assumptions capture possible failures of the system components,
and the guarantees capture safety requirements related to power distribution.


title: Exponential fading to white of black holes in quantum gravity

abstract:
  Quantization of the gravitational field may allow the existence of a decay
channel of black holes into white holes with an explicit time-reversal
symmetry. The definition of a meaningful decay probability for this channel is
studied in spherically symmetric situations. As a first nontrivial calculation,
we present the functional integration over a set of geometries using a
single-variable function to interpolate between black-hole and white-hole
geometries in a bounded region of spacetime. This computation gives a finite
result which depends only on the Schwarzschild mass and a parameter measuring
the width of the interpolating region. The associated probability distribution
displays an exponential decay law on the latter parameter, with a mean lifetime
inversely proportional to the Schwarzschild mass. In physical terms this would
imply that matter collapsing to a black hole from a finite radius bounces back
elastically and instantaneously, with negligible time delay as measured by
external observers. These results invite to reconsider the ultimate nature of
astrophysical black holes, providing a possible mechanism for the formation of
black stars instead of proper general relativistic black holes. The existence
of both this decay channel and black stars can be tested in future observations
of gravitational waves.


title: Nonlinear plasmonics at high temperatures

abstract:
  We solve the Maxwell and heat equations self-consistently for metal
nanoparticles under intense continuous wave (CW) illumination. Unlike previous
studies, we rely on {\em experimentally}-measured data for the metal
permittivity for increasing temperature and for the visible spectral range. We
show that the thermal nonlinearity of the metal can lead to substantial
deviations from the predictions of the linear model for the temperature and
field distribution, and thus, can explain qualitatively the strong nonlinear
scattering from such configurations observed experimentally. We also show that
the incompleteness of existing data of the temperature dependence of the
thermal properties of the system prevents reaching a quantitative agreement
between the measured and calculated scattering data. This modelling approach is
essential for the identification of the underlying physical mechanism
responsible for the thermo-optical nonlinearity of the metal and should be
adopted in all applications of high temperature nonlinear plasmonics,
especially for refractory metals, both for CW and pulsed illumination.


title:
Travelling waves and a fruitful `time' reparametrization in relativistic
  electrodynamics

abstract:
  We simplify the nonlinear equations of motion of charged particles in an
external electromagnetic field that is the sum of a plane travelling wave
F_t(ct-z) and a static part F_s(x,y,z): by adopting the light-like coordinate
ct-z instead of time t as an independent variable in the Action, Lagrangian and
Hamiltonian, and deriving the new Euler-Lagrange and Hamilton equations
accordingly, we make the unknown z(t) disappear from the argument of F_t. We
study and solve first the single particle equations in few significant cases of
extreme accelerations. In particular we obtain a rigorous formulation of a
Lawson-Woodward-type (no-final-acceleration) theorem and a compact derivation
of cyclotron autoresonance, beside new solutions in the presence of uniform
F_s. We then extend our method to plasmas in hydrodynamic conditions and apply
it to plane problems: the system of partial differential equations may be
partially solved and sometimes even completely reduced to a family of decoupled
systems of ordinary ones; this occurs e.g. with the impact of the travelling
wave on a vacuum-plasma interface (what may produce the slingshot effect).
Since Fourier analysis plays no role in our general framework, the method can
be applied to all kind of travelling waves, ranging from almost monochromatic
to socalled "impulses", which contain few, one or even no complete cycle.

categories: math-ph astro-ph.HE math.MP physics.acc-ph


title: Block Models and Personalized PageRank

abstract:
  Methods for ranking the importance of nodes in a network have a rich history
in machine learning and across domains that analyze structured data. Recent
work has evaluated these methods though the seed set expansion problem: given a
subset $S$ of nodes from a community of interest in an underlying graph, can we
reliably identify the rest of the community? We start from the observation that
the most widely used techniques for this problem, personalized PageRank and
heat kernel methods, operate in the space of landing probabilities of a random
walk rooted at the seed set, ranking nodes according to weighted sums of
landing probabilities of different length walks. Both schemes, however, lack an
a priori relationship to the seed set objective. In this work we develop a
principled framework for evaluating ranking methods by studying seed set
expansion applied to the stochastic block model. We derive the optimal gradient
for separating the landing probabilities of two classes in a stochastic block
model, and find, surprisingly, that under reasonable assumptions the gradient
is asymptotically equivalent to personalized PageRank for a specific choice of
the PageRank parameter $\alpha$ that depends on the block model parameters.
This connection provides a novel formal motivation for the success of
personalized PageRank in seed set expansion and node ranking generally. We use
this connection to propose more advanced techniques incorporating higher
moments of landing probabilities; our advanced methods exhibit greatly improved
performance despite being simple linear classification rules, and are even
competitive with belief propagation.


title:
Arbitrarily large numbers of kink internal modes in inhomogeneous
  sine-Gordon equations

abstract:
  We prove the existence of an infinite number of internal (shape) modes of
sine-Gordon solitons in the presence of some inhomogeneous long-range forces,
provided some conditions are satisfied.


title: Response to "Verifying quantum superpositions at metre scales"

abstract:
  The preceding BCA (Stamper-Kurn et. al., arXiv:1607.01454) asserts that our
observation of interference contrast in a half-metre-scale atom interferometer
(Kovachy et. al., Nature 528, 530-3 (2015)) does not prove the existence of
macroscopic quantum superpositions and hence does not test quantum mechanics at
long length scales. Moreover, the BCA implies that intrinsic atomic
interactions or technical imperfections could prevent the application of our
work to future differential measurements. On the contrary, we argue the
following: i) in standard quantum mechanics, there is no known mechanism in our
system that prohibits its use in future differential measurement applications;
ii) our experiment tests quantum mechanics in that it constrains any
modifications that would reduce contrast in an interferometer with arms that
propagate over widely separated trajectories; and iii) using a standard
definition of superposition, our observation of interference results from
quantum superposition at the half-metre scale. In particular, quantum
superposition is a more general concept than first-order coherence.


title:
Simulating galaxy formation with black hole driven thermal and kinetic
  feedback

abstract:
  The inefficiency of star formation in massive elliptical galaxies is widely
believed to be caused by the interactions of an active galactic nucleus (AGN)
with the surrounding gas. Achieving a sufficiently rapid reddening of
moderately massive galaxies without expelling too many baryons has however
proven difficult for hydrodynamical simulations of galaxy formation, prompting
us to explore a new model for the accretion and feedback effects of
supermassive black holes. For high accretion rates relative to the Eddington
limit, we assume that a fraction of the accreted rest mass energy heats the
surrounding gas thermally, similar to the `quasar mode' in previous work. For
low accretion rates, we invoke a new, pure kinetic feedback model which imparts
momentum into the surrounding gas in a stochastic manner. These two modes of
feedback are motivated both by theoretical conjectures for the existence of
different types of accretion flows as well as recent observational evidence for
the importance of kinetic AGN winds in quenching galaxies. We find that a large
fraction of the injected kinetic energy in this mode thermalises via shocks in
the surrounding gas, thereby providing a distributed heating channel. In
cosmological simulations, the resulting model produces red, non star-forming
massive elliptical galaxies, and achieves realistic gas fractions, black hole
growth histories and thermodynamic profiles in large haloes.


title:
HST Imaging of the Local Volume Dwarf Galaxies Pisces A&B: Prototypes
  for Local Group Dwarfs

abstract:
  We present observations of the Pisces A and B galaxies with the Advanced
Camera for Surveys on the Hubble Space Telescope. Photometry from these images
clearly resolve a Red Giant Branch for both objects, demonstrating that they
are nearby dwarf galaxies. We describe a Bayesian inferential approach to
determining the distance to these galaxies using the magnitude of the tip of
the RGB, and then apply this approach to these galaxies. We also provide the
full probability distributions for parameters derived using this approach. This
reveals the distance to these galaxies as $5.64^{+0.13}_{-0.15} \, {\rm Mpc}$
and $8.89^{+0.75}_{-0.85} \, {\rm Mpc}$ for Pisces A and B, respectively,
placing both within the Local Volume but not the Local Group. We estimate the
star formation histories of these galaxies, which suggests that they have
recently undergone an increase in their star formation rates. Together these
yield luminosities for Pisces A and B of $M_V=-11.57^{+0.06}_{-0.05}$ and
$-12.9 \pm 0.2$, respectively, and estimated stellar masses of
$\log(M_*/M_{\odot})= 7.0^{+0.4}_{-1.7}$ and $7.5^{+0.3}_{-1.8}$. We further
show that these galaxies are likely at the boundary between nearby voids and
higher-density filamentary structure. This suggests that they are entering a
higher-density region from voids, where they would have experienced delayed
evolution, consistent with their recent increased star formation rates. If this
is indeed the case, they are useful for study as proxies of the galaxies that
later evolved into typical Local Group satellite galaxies.


title:
Radiative transfer meets Bayesian statistics: where does a galaxy's
  [CII] emission come from?

abstract:
  The [CII] 158$\mu$m emission line can arise in all phases of the ISM,
therefore being able to disentangle the different contributions is an important
yet unresolved problem when undertaking galaxy-wide, integrated [CII]
observations. We present a new multi-phase 3D radiative transfer interface that
couples Starburst99, a stellar spectrophotometric code, with the
photoionisation and astrochemistry codes Mocassin and 3D-PDR. We model entire
star forming regions, including the ionised, atomic and molecular phases of the
ISM, and apply a Bayesian inference methodology to parametrise how the fraction
of the [CII] emission originating from molecular regions, $f_{[CII],mol}$,
varies as a function of typical integrated properties of galaxies in the local
Universe. The main parameters responsible for the variations of $f_{[CII],mol}$
are specific star formation rate (sSFR), gas phase metallicity, HII region
electron number density ($n_e$), and dust mass fraction. For example,
$f_{[CII],mol}$ can increase from 60% to 80% when either $n_e$ increases from
10$^{1.5}$ to 10$^{2.5}$cm$^{-3}$, or SSFR decreases from $10^{-9.6}$ to
$10^{-10.6}$ yr$^{-1}$. Our model predicts for the Milky Way that
$f_{[CII],mol}$$=75.8\pm5.9$%, in agreement with the measured value of 75%.
When applying the new prescription to a complete sample of galaxies from the
Herschel Reference Survey (HRS), we find that anywhere from 60 to 80% of the
total integrated [CII] emission arises from molecular regions.