title: Benchmark for License Plate Character Segmentation

abstract:
  Automatic License Plate Recognition (ALPR) has been the focus of many
researches in the past years. In general, ALPR is divided into the following
problems: detection of on-track vehicles, license plates detection, segmention
of license plate characters and optical character recognition (OCR). Even
though commercial solutions are available for controlled acquisition
conditions, e.g., the entrance of a parking lot, ALPR is still an open problem
when dealing with data acquired from uncontrolled environments, such as roads
and highways when relying only on imaging sensors. Due to the multiple
orientations and scales of the license plates captured by the camera, a very
challenging task of the ALPR is the License Plate Character Segmentation (LPCS)
step, which effectiveness is required to be (near) optimal to achieve a high
recognition rate by the OCR. To tackle the LPCS problem, this work proposes a
novel benchmark composed of a dataset designed to focus specifically on the
character segmentation step of the ALPR within an evaluation protocol.
Furthermore, we propose the Jaccard-Centroid coefficient, a new evaluation
measure more suitable than the Jaccard coefficient regarding the location of
the bounding box within the ground-truth annotation. The dataset is composed of
2,000 Brazilian license plates consisting of 14,000 alphanumeric symbols and
their corresponding bounding box annotations. We also present a new
straightforward approach to perform LPCS efficiently. Finally, we provide an
experimental evaluation for the dataset based on four LPCS approaches and
demonstrate the importance of character segmentation for achieving an accurate
OCR.


title:
Two-layer anti-reflection coating with mullite and polyimide foam for
  large-diameter cryogenic infrared filters

abstract:
  We have developed a novel two-layer anti-reflection (AR) coating method for
large-diameter infrared (IR) filters made of alumina, for the use at cryogenic
temperatures in millimeter wave measurements. Thermally- sprayed mullite and
polyimide foam (Skybond Foam) are used as the AR material. An advantage of the
Skybond Foam is that the index of refraction is chosen between 1.1 and 1.7 by
changing the filling factor. Combination with mullite is suitable for wide-band
millimeter wave measurements with sufficient IR cutoff capability. We present
the material properties, fabrication of a large-diameter IR filter made of
alumina with this AR coating method, and characterizations at cryogenic
temperatures. This technology can be applied to a low-temperature receiver
system with a large-diameter focal plane for next-generation cosmic microwave
background (CMB) polarization measurements, such as POLARBEAR-2 (PB-2).


title: Open Effective Field Theories from Deeply Inelastic Reactions

abstract:
  Effective field theories have often been applied to systems with deeply
inelastic reactions that produce particles with large momenta outside the
domain of validity of the effective theory. The effects of the deeply inelastic
reactions have been taken into account in previous work by adding local
anti-Hermitian terms to the effective Hamiltonian. Here we show that when
multi-particle systems are considered, an additional modification is required
in equations governing the density matrix. We define an effective density
matrix by tracing over the states containing high-momentum particles, and show
that it satisfies a Lindblad equation, with local Lindblad operators determined
by the anti-Hermitian terms in the effective Hamiltonian density.


title: Calabi-Yau manifolds with isolated conical singularities

abstract:
  Let $X$ be a complex projective variety with only canonical singularities and
with trivial canonical bundle. Let $L$ be an ample line bundle on $X$. Assume
that the pair $(X,L)$ is the flat limit of a family of smooth polarized
Calabi-Yau manifolds. Assume that for each singular point $x \in X$ there exist
a Kahler-Einstein Fano manifold $Z$ and a positive integer $q$ dividing $K_Z$
such that $-\frac{1}{q}K_Z$ is very ample and such that the germ $(X,x)$ is
locally analytically isomorphic to a neighborhood of the vertex of the
blow-down of the zero section of $\frac{1}{q}K_{Z}$. We prove that up to
biholomorphism, the unique weak Ricci-flat Kahler metric representing $2\pi
c_1(L)$ on $X$ is asymptotic at a polynomial rate near $x$ to the natural
Ricci-flat Kahler cone metric on $\frac{1}{q}K_Z$ constructed using the Calabi
ansatz. In particular, our result applies if $(X, \mathcal{O}(1))$ is a nodal
quintic threefold in $\mathbb{P}^4$. This provides the first known examples of
compact Ricci-flat manifolds with non-orbifold isolated conical singularities.


title:
Critical points, phase transitions and water-like anomalies for an
  isotropic two length scale potential with increasing attractive well

abstract:
  Molecular Dynamic and Monte Carlo studies are performed in a family of
core-softened (CS) potential, composed by two length scales: a repulsive
shoulder at short distances and the another a variable scale, that can be
repulsive or strongly attractive depending on the parameters used. The density,
diffusion and structural anomalous regions in the pressure versus temperature
phase diagram shrink in pressure as the system becomes more attractive. The
liquid-liquid transition appears as a consequence of the non monotonic behavior
of the density versus pressure isotherms with the increase of the attraction
well. We found that the liquid-gas phase transition is Ising-like for all the
CS potentials and its critical temperature increases with the increase of the
attraction. No Ising-like behavior for the liquid-liquid phase transition was
detected in the Monte Carlo simulations what might be due to the presence of
stable solid phases.


title: Rules for collaborative scientific writing

abstract:
  Several years ago, one of us, having noticed that inexperienced scientists
tend to make largely the same mistakes while writing their first papers, was
compelled to write a one-page note summarizing some dos and don'ts intended to
help take care of common problems before they occur. Since these days the
majority of research papers are written collaboratively by groups of
co-authors, we are compelled to extend these recommendations to collaborative
writing as we observe groups of co-authors falling into the same traps again
and again.


title: Aubry-Mather Theory for Conformally Symplectic Systems

abstract:
  In this article we develop an analogue of Aubry-Mather theory for a class of
dissipative systems, namely conformally symplectic systems, and prove the
existence of interesting invariant sets, which, in analogy to the conservative
case, will be called the Aubry and the Mather sets. Besides describing their
structure and their dynamical significance, we shall analyze their
attracting/repelling properties, as well as their noteworthy role in driving
the asymptotic dynamics of the system.


title: A Singularity in the Kirchhoff's Circuit Equations

abstract:
  Students often have difficulty in understanding qualitatively the behaviour
of simple electric circuits. In particular, as different studies have shown,
they find multiple batteries connected in multiple loops difficult to analyse.
In a recent paper [Phys. Educ. 50 568 (2015)], we showed such an electric
circuit, which consists of ideal batteries connected in parallel, that couldn't
be solved by the existing circuit analysis methods. In this paper, we shall
introduce a new mathematical method of solving simple electric circuits from
the solutions of more general circuits and show that the currents, in this
particular circuit, take the indeterminate 0/0 form. We shall also present some
of the implications of teaching the method. We believe that the description
presented in this paper should help the instructors in teaching the behaviour
of multiple batteries connected in parallel.


title: Transitive Avoidance Games

abstract:
  Positional games are a well-studied class of combinatorial game. In their
usual form, two players take turns to play moves in a set (`the board'), and
certain subsets are designated as `winning': the first person to occupy such a
set wins the game. For these games, it is well known that (with correct play)
the game cannot be a second-player win.
  In the avoidance (or mis\`{e}re) form, the first person to occupy such a set
\emph{loses} the game. Here it would be natural to expect that the game cannot
be a first-player win, at least if the game is transitive, meaning that all
points of the board look the same. Our main result is that, contrary to this
expectation, there are transitive games that are first-player wins, for all
board sizes which are not prime or a power of 2.
  Further, we show that such games can have additional properties such as
stronger transitivity conditions, fast winning times, and `small' winning sets.


title: Raman study of a work of art fragment

abstract:
  The purpose of the present report was the study and identification of an
unspecified sample on a work of art by means only of a microscope coupled to a
Raman spectrometer. The origin of the fragment was unknown. The Raman spectra
on the virgin sample were giving no results because of a deteriorated surface
treatment, in spite of the evident blue color identified by microscopic visual
inspection. The sample fragmentation and the preparation of a KBr pellet
allowed the distribution of the painting layers of the different components on
a flat substrate reducing surface effects. Selecting the areas of different
color and focusing there it was possible to identify the pigments from their
Raman spectra locally acquired by selective excitation. Raman spectra were
assigned by comparison with published databases. It was possible to connect
Carbon Black and Orange iron oxide, as documented historically, as constituents
of Azurite preparatory layer Morellone, according to a technique generally
employed to allow the use of Azurite blue pigment on frescos, consequently the
identification of typology of work of art was deducted and attributed to a
fresco.


title:
Orbital-differentiated coherence-incoherence crossover identified by
  photoemission spectroscopy in LiFeAs

abstract:
  In the iron-based superconductors (FeSCs), orbital differentiation is an
important phenomenon, whereby correlations stronger on the dxy orbital than on
the dxz/yz orbital yield quasi-particles with dxy} orbital character having
larger mass renormalization and abnormal temperature evolution. However, the
physical origin of this orbital differentiation is debated between the Hund's
coupling induced unbinding of spin and orbital degrees of freedom and the
Hubbard interaction instigated orbital selective Mott transition. Here we use
angle-resolved photoemission spectroscopy to identify an orbital-dependent
correlation-induced quasi-particle (QP) anomaly in LiFeAs. The excellent
agreement between our photoemission measurements and first-principles many-body
theory calculations shows that the orbital-differentiated QP lifetime anomalies
in LiFeAs are controlled by the Hund's coupling.


title: Completing the proof of "Generic quantum nonlocality"

abstract:
  In a paper by Popescu and Rohrlich [Phys. Lett. A 166, 293 (1992)] a proof
has been presented showing that any pure entangled multiparticle quantum state
violates some Bell inequality. We point out a gap in this proof, but we also
give a construction to close this gap. It turns out that with some extra effort
all the results from the aforementioned publication can be proven. Our
construction shows how two-particle entanglement can be generated via
performing local projections on a multiparticle state.


title: Scaling of anomalous Hall effect in ferromagnetic thin films

abstract:
  We propose a new scaling law for anomalous Hall effect in ferromagnetic thin
films by distinguishing three scattering sources, namely, bulk impurity,
phonon, and more importantly a rough surface. This new scaling law fits the
recent experimental data excellently with constant coefficients that are
independent of temperature and film thickness. This is in stark constrast with
previous scaling laws that use temperature/thickness dependent fitting
coefficients, and is a strong indicator that this law captures the essential
physics. By intepretating the experiments for Fe, Co, and Ni with this new law,
we conclude that (i) the phonon-induced skew scattering is unimportant as
expected; (ii) contribution from the impurity-induced skew scattering is
negative; (iii) the intrinsic (extrinsic) mechanism dominates in Fe (Co), and
both the extrinsic and the intrinsic contribution are important in Ni.


title: Exploring high-z galaxies with the E-ELT

abstract:
  In this paper we present simulated observations of galaxies at z=2 and z=3 to
probe the capabilities of next-generation telescopes (E-ELT and JWST) to
measure the structural and photometrical properties of high redshift galaxies.
We carry out an extensive set of simulations of high redshift galaxies adopting
the specifications of the E-ELT first light instrument MICADO. The main
parameters (sizes, Sersic index, magnitudes) of the galaxies are measured using
GALFIT and the accuracy of the determinations is assessed by comparing the
input values to the measurements from many runs with different statistical
noise. We also address the effects on the measurements accuracy of possible
spatial variation of the PSF in the field. We find that from 3h exposure E-ELT
near-IR images of galaxies at z=2 and z=3 it will be possible to measure the
size, the total magnitude and the galaxy morphology with an accuracy of 5% for
objects as faint as H=25 and half light size of 0.2 arcsec. The effective
radius of compact, early type galaxies will also be recovered with 5% accuracy,
provided that their half light size exceeds 20 mas. These results are compared
with those expected from simulated observations obtained with NIRCam on board
of the JWST.


title: Design Patterns in Beeping Algorithms: Examples, Emulation, and Analysis

abstract:
  We consider networks of processes which interact with beeps. In the basic
model defined by Cornejo and Kuhn (2010), processes can choose in each round
either to beep or to listen. Those who beep are unable to detect simultaneous
beeps. Those who listen can only distinguish between silence and the presence
of at least one beep. We refer to this model as $BL$ (beep or listen). Stronger
models exist where the nodes can detect collision while they are beeping
($B_{cd}L$), listening ($BL_{cd}$), or both ($B_{cd}L_{cd}$). Beeping models
are weak in essence and even simple tasks are difficult or unfeasible within.
  We present a set of generic building blocks (design patterns) which seem to
occur frequently in the design of beeping algorithms. They include multi-slot
phases: the fact of dividing the main loop into a number of specialised slots;
exclusive beeps: having a single node beep at a time in a neighbourhood (within
one or two hops); adaptive probability: increasing or decreasing the
probability of beeping to produce more exclusive beeps; internal (resp.
peripheral) collision detection: for detecting collision while beeping (resp.
listening). Based on these patterns, we provide algorithms for a number of
basic problems, including colouring, 2-hop colouring, degree computation, 2-hop
MIS, and collision detection (in $BL$). The patterns make it possible to
formulate these algorithms in a rather concise and elegant way. Their analyses
are more technical; one of them improves significantly upon that of the best
known MIS algorithm by Jeavons et al. (2016). Finally, inspired by a technique
from Afek et al. (2013), our last contribution is to show that any Las Vegas
algorithm relying on collision detection can be transposed into a Monte Carlo
algorithm without collision detection at the cost of a logarithmic slowdown,
which we prove is optimal.


title: Are human interactivity times lognormal?

abstract:
  In this paper, we are analyzing the interactivity time, defined as the
duration between two consecutive tasks such as sending emails, collecting
friends and followers and writing comments in online social networks (OSNs).
The distributions of these times are heavy tailed and often described by a
power-law distribution. However, power-law distributions usually only fit the
heavy tail of empirical data and ignore the information in the smaller value
range. Here, we argue that the durations between writing emails or comments,
adding friends and receiving followers are likely to follow a lognormal
distribution.
  We discuss the similarities between power-law and lognormal distributions,
show that binning of data can deform a lognormal to a power-law distribution
and propose an explanation for the appearance of lognormal interactivity times.
The historical debate of similarities between lognormal and power-law
distributions is reviewed by illustrating the resemblance of measurements in
this paper with the historical problem of income and city size distributions.


title: When does NIP transfer from fields to henselian expansions?

abstract:
  Let $K$ be an NIP field and let $v$ be a henselian valuation on $K$. We ask
whether $(K,v)$ is NIP as a valued field. By a result of Shelah, we know that
if $v$ is externally definable, then $(K,v)$ is NIP. Using the definability of
the canonical $p$-henselian valuation, we show that whenever the residue field
of $v$ is not separably closed, then $v$ is externally definable. In the case
of separably closed residue field, we show that $(K,v)$ is NIP as a pure valued
field.


title:
Synthesis of passive lossless metasurfaces using auxiliary fields for
  reflectionless beam splitting and perfect reflection

abstract:
  We introduce a paradigm for accurate design of metasurfaces for intricate
beam manipulation, implementing functionalities previously considered
impossible to achieve with passive lossless elements. The key concept involves
self-generation of auxiliary evanescent fields which facilitate the required
local power conservation, without interfering with the device performance in
the far field. We demonstrate our scheme by presenting exact reactive solutions
to the challenging problems of reflectionless beam splitting and perfect
reflection, verified via full wave simulations.


title:
Estimating Current-Flow Closeness Centrality with a Multigrid Laplacian
  Solver

abstract:
  Matrices associated with graphs, such as the Laplacian, lead to numerous
interesting graph problems expressed as linear systems. One field where
Laplacian linear systems play a role is network analysis, e. g. for certain
centrality measures that indicate if a node (or an edge) is important in the
network. One such centrality measure is current-flow closeness. To allow
network analysis workflows to profit from a fast Laplacian solver, we provide
an implementation of the LAMG multigrid solver in the NetworKit package,
facilitating the computation of current-flow closeness values or related
quantities. Our main contribution consists of two algorithms that accelerate
the current-flow computation for one node or a reasonably small node subset
significantly. One sampling-based algorithm provides an unbiased estimation of
the related electrical farness, the other one is based on the
Johnson-Lindenstrauss transform. Our inexact algorithms lead to very accurate
results in practice. Thanks to them one is now able to compute an estimation of
current-flow closeness of one node on networks with tens of millions of nodes
and edges within seconds or a few minutes. From a network analytical point of
view, our experiments indicate that current-flow closeness can discriminate
among different nodes significantly better than traditional shortest-path
closeness and is also considerably more resistant to noise -- we thus show that
two known drawbacks of shortest-path closeness are alleviated by the
current-flow variant.


title: Triple correlations of Fourier coefficients of cusp forms

abstract:
  We treat an unbalanced shifted convolution sum of Fourier coefficients of
cusp forms. As a consequence, we obtain an upper bound for correlation of three
Hecke eigenvalues of holomorphic cusp forms $\sum_{H\leq h\leq
2H}W\big(\frac{h}{H}\big)\sum_{X\leq n\leq
2X}\lambda_{1}(n-h)\lambda_{2}(n)\lambda_{3}(n+h)$, which is nontrivial
provided that $H\geq X^{2/3+\varepsilon}$. The result can be viewed as a
cuspidal analogue of a recent result of Blomer on triple correlations of
divisor functions.


title:
A low-rank based estimation-testing procedure for matrix-covariate
  regression

abstract:
  Matrix-covariate is now frequently encountered in many biomedical researches.
It is common to fit conventional statistical models by vectorizing
matrix-covariate. This strategy, however, results in a large number of
parameters, while the available sample size is relatively too small to have
reliable analysis results. To overcome the problem of high-dimensionality in
hypothesis testing, variance component test has been proposed with promise
detection power, but is not straightforward to provide estimates of effect
size. In this work, we overcome the problem of high-dimensionality by utilizing
the inherent structure of the matrix-covariate. The advantage is that
estimation and hypothesis testing can be conducted simultaneously as in the
conventional case, while the estimation efficiency and detection power can be
largely improved, due to a parsimonious parameterization for the coefficients
of matrix-covariate. Our method is applied to test the significance of
gene-gene interactions in the PSQI data, and is applied to test if
electroencephalography is associated with the alcoholic status in the EEG data,
wherein sparse effects and low-rank effects of matrix-covariates are
identified, respectively.


title:
Additive interfacial chiral interaction in multilayers for stabilization
  of small individual skyrmion at room temperature

abstract:
  Facing the ever-growing demand for data storage will most probably require a
new paradigm. Nanoscale magnetic skyrmions are anticipated to solve this issue
as they are arguably the smallest spin textures in magnetic thin films in
nature. We designed cobalt-based multilayered thin films where the cobalt layer
is sandwiched between two heavy metals providing additive interfacial
Dzyaloshinskii-Moriya interactions, which reach a value close to 2 mJ m-2 in
the case of the Ir|Co|Pt asymmetric multilayers. Using a
magnetization-sensitive scanning x-ray transmission microscopy technique, we
imaged small magnetic domains at very low field in these multilayers. The study
of their behavior in perpendicular magnetic field allows us to conclude that
they are actually magnetic skyrmions stabilized by the large
Dzyaloshinskii-Moriya interaction. This discovery of stable sub-100 nm
individual skyrmions at room temperature in a technologically relevant material
opens the way for device applications in a near future.


title:
From Behavior to Sparse Graphical Games: Efficient Recovery of
  Equilibria

abstract:
  In this paper we study the problem of exact recovery of the pure-strategy
Nash equilibria (PSNE) set of a graphical game from noisy observations of joint
actions of the players alone. We consider sparse linear influence games --- a
parametric class of graphical games with linear payoffs, and represented by
directed graphs of n nodes (players) and in-degree of at most k. We present an
$\ell_1$-regularized logistic regression based algorithm for recovering the
PSNE set exactly, that is both computationally efficient --- i.e. runs in
polynomial time --- and statistically efficient --- i.e. has logarithmic sample
complexity. Specifically, we show that the sufficient number of samples
required for exact PSNE recovery scales as $\mathcal{O}(\mathrm{poly}(k) \log
n)$. We also validate our theoretical results using synthetic experiments.


title: Transformation of a wavefunction under changes of reference frame

abstract:
  A simple procedure to derive the transformation of a wavefunction under a
change of reference frame is applied to some examples and its relation with the
transformation of the Hamilton principal function is studied.


title:
Instantaneous spreading versus space localization for nonrelativistic
  quantum systems

abstract:
  A theorem of Hegerfeldt (Instantaneous spreading and Einstein causality in
quantum theory, Ann. Phys. Leipzig vol. 7, 716-725 (1998)) establishes, for a
class of quantum systems, a dichotomy between those which are permanently
localized in a bounded region of space, and those exhibiting instantaneous
spreading. We analyse in some detail the physical inconsistencies which follow
from both of these options, and formulate which, in our view, are the basic
open problems.


title:
On the Ornstein-Zernike equation for stationary cluster processes and
  the random connection model

abstract:
  In the first part of this paper we consider a general stationary subcritical
cluster model in $\mathbb{R}^d$. The associated pair-connectedness function can
be defined in terms of two-point Palm probabilities of the underlying point
process. Using Palm calculus and Fourier theory we solve the Ornstein-Zernike
equation (OZE) under quite general distributional assumptions. In the second
part of the paper we discuss the analytic and combinatorial properties of the
OZE-solution in the special case of a Poisson driven random connection model.


title: Modelling movement for collective adaptive systems with CARMA

abstract:
  Space and movement through space play an important role in many collective
adaptive systems (CAS). CAS consist of multiple components interacting to
achieve some goal in a system or environment that can change over time. When
these components operate in space, then their behaviour can be affected by
where they are located in that space. Examples include the possibility of
communication between two components located at different points, and rates of
movement of a component that may be affected by location. The CARMA language
and its associated software tools can be used to model such systems. In
particular, a graphical editor for CARMA allows for the specification of
spatial structure and generation of templates that can be used in a CARMA model
with space. We demonstrate the use of this tool to experiment with a model of
pedestrian movement over a network of paths.


title: Agnostic cosmology in the CAMEL framework

abstract:
  Cosmological parameter estimation is traditionally performed in the Bayesian
context. By adopting an "agnostic" statistical point of view, we show the
interest of confronting the Bayesian results to a frequentist approach based on
profile-likelihoods. To this purpose, we have developed the Cosmological
Analysis with a Minuit Exploration of the Likelihood ("CAMEL") software.
Written from scratch in pure C++, emphasis was put in building a clean and
carefully-designed project where new data and/or cosmological computations can
be easily included.
  CAMEL incorporates the latest cosmological likelihoods and gives access from
the very same input file to several estimation methods: (i) A high quality
Maximum Likelihood Estimate (a.k.a "best fit") using MINUIT ; (ii) profile
likelihoods, (iii) a new implementation of an Adaptive Metropolis MCMC
algorithm that relieves the burden of reconstructing the proposal distribution.
  We present here those various statistical techniques and roll out a full
use-case that can then used as a tutorial. We revisit the $\Lambda$CDM
parameters determination with the latest Planck data and give results with both
methodologies. Furthermore, by comparing the Bayesian and frequentist
approaches, we discuss a "likelihood volume effect" that affects the optical
reionization depth when analyzing the high multipoles part of the Planck data.
  The software, used in several Planck data analyzes, is available from
http://camel.in2p3.fr. Using it does not require advanced C++ skills.


title: PLC-controlled cryostats for the BlackGEM and MeerLICHT detectors

abstract:
  BlackGEM (BG) is an array of telescopes, currently under development at the
Radboud University Nijmegen and at NOVA. It targets the detection of the
optical counterparts of gravitational waves. The first 3 BG telescopes are
planned to be installed in 2018 at the La Silla observatory. A single prototype
telescope, named MeerLICHT, will already be commissioned early 2017 in
Sutherland to provide an optical complement for the MeerKAT radio array. The BG
array consists of, initially, a set of 3 robotic 65-cm wide-field telescopes.
Each telescope is equipped with a single STA1600 CCD detector with 10.5k x
10.5k 9-mum pixels that covers a 2.7 square degrees field of view. The
cryostats for housing these detectors are developed and built at the KU Leuven
University. The operational model of BG requires long periods of reliable
ands-off operation. Therefore, we designed the cryostats for long vacuum hold
time and we make use of a closed-cycle cooling system, based on Polycold PCC
Joule-Thomson coolers. A single programmable logic controller (PLC) controls
the cryogenic systems of several BG telescopes simultaneously, resulting in a
highly reliable, cost-efficient and maintenance-friendly system. PLC-based
cryostat control offers some distinct advantages, especially for a robotic
facility. Apart of temperature monitoring and control, the PLC also monitors
the vacuum quality, the power supply and the status of the PCC coolers
(compressor power consumption and temperature, pressure in the gas lines,
etc.). Furthermore, it provides an alarming system and safe and reproducible
procedures for automatic cool down and warm up. The communication between PLC
and higher-level software takes place via the OPC-UA protocol, offering a
simple to implement, yet very powerful interface. Finally, a touch-panel
display on the PLC provides the operator with a user-friendly and robust
technical interface.


title: Challenges in Quantitative Abstractions for Collective Adaptive Systems

abstract:
  Like with most large-scale systems, the evaluation of quantitative properties
of collective adaptive systems is an important issue that crosscuts all its
development stages, from design (in the case of engineered systems) to runtime
monitoring and control. Unfortunately it is a difficult problem to tackle in
general, due to the typically high computational cost involved in the analysis.
This calls for the development of appropriate quantitative abstraction
techniques that preserve most of the system's dynamical behaviour using a more
compact representation. This paper focuses on models based on ordinary
differential equations and reviews recent results where abstraction is achieved
by aggregation of variables, reflecting on the shortcomings in the state of the
art and setting out challenges for future research.


title: TASI Lectures on the Higher Spin - CFT duality

abstract:
  In these lectures we give an overview of the duality between gravitational
theories of massless higher spin fields in AdS and large N vector models. We
first review the original higher spin/vector model duality conjectured by
Klebanov and Polyakov, and then discuss its generalizations involving vector
models coupled to Chern-Simons gauge fields. We proceed to review some aspects
of the theory of massless higher spins, starting with the Fronsdal equations
for free fields and moving on to the fully non-linear Vasiliev equations in
four dimensions. We end by reviewing some recent tests of the higher
spin/vector model duality at the level of correlation functions and one-loop
partition functions.


title:
An Empirical Correction for Moderate Multiple Scattering in
  Super-Heterodyne Light Scattering

abstract:
  Frequency domain super-heterodyne laser light scattering is utilized in a low
angle integral measurement configuration to determine flow and diffusion in
charged sphere suspensions showing moderate to strong multiple scattering. We
introduce an empirical correction to subtract the multiple scattering
background and isolate the singly scattered light. We demonstrate the excellent
feasibility of this simple approach for turbid suspensions of transmittance
T>0.4. We study the particle concentration dependence of the electro-kinetic
mobility in low salt aqueous suspension over an extended concentration regime
and observe a maximum at intermediate concentrations. We further use our scheme
for measurements of the self-diffusion coefficients in the fluid samples in the
absence or presence of shear, as well as in polycrystalline samples during
crystallization and coarsening. We discuss the scope and limits of our approach
as well as possible future applications.


title: Possible existence of optical communication channels in the brain

abstract:
  Given that many fundamental questions in neuroscience are still open, it
seems pertinent to explore whether the brain might use other physical
modalities than the ones that have been discovered so far. In particular it is
well established that neurons can emit photons, which prompts the question
whether these biophotons could serve as signals between neurons, in addition to
the well-known electro-chemical signals. For such communication to be targeted,
the photons would need to travel in waveguides. Here we show, based on detailed
theoretical modeling, that myelinated axons could serve as photonic waveguides,
taking into account realistic optical imperfections. We propose experiments,
both \textit{in vivo} and \textit{in vitro}, to test our hypothesis. We discuss
the implications of our results, including the question whether photons could
mediate long-range quantum entanglement in the brain.

categories: q-bio.NC physics.bio-ph physics.optics quant-ph


title:
The sequential functionals of type $(\iota \rightarrow \iota)^n
  \rightarrow \iota$ form a dcpo for all $n \in \Bbb N$

abstract:
  We prove that the sequential functionals of some fixed types at type level 2,
taking finite sequences of unary functions as arguments, do form a directed
complete partial ordering. This gives a full characterisation of for which
types the partially ordered set of sequential functionals has this property. As
a tool, we prove a normal form theorem for the finite sequential functionals of
the types in question,


title:
GAMA/H-ATLAS: Common star-formation rate indicators and their dependence
  on galaxy physical parameters

abstract:
  We compare common star-formation rate (SFR) indicators in the local Universe
in the GAMA equatorial fields (around 160 sq. deg.), using ultraviolet (UV)
photometry from GALEX, far-infrared (FIR) and sub-millimetre (sub-mm)
photometry from H-ATLAS, and Halpha spectroscopy from the GAMA survey. With a
high-quality sample of 745 galaxies (median redshift 0.08), we consider three
SFR tracers: UV luminosity corrected for dust attenuation using the UV spectral
slope beta (SFRUV,corr), Halpha line luminosity corrected for dust using the
Balmer decrement (BD) (SFRHalpha,corr), and the combination of UV and IR
emission (SFRUV+IR). We demonstrate that SFRUV,corr can be reconciled with the
other two tracers after applying attenuation corrections by calibrating IRX
(i.e. the IR to UV luminosity ratio) and attenuation in the Halpha (derived
from BD) against beta. However, beta on its own is very unlikely to be a
reliable attenuation indicator. We find that attenuation correction factors
depend on parameters such as stellar mass, z and dust temperature (Tdust), but
not on Halpha equivalent width (EW) or Sersic index. Due to the large scatter
in the IRX vs beta correlation, when compared to SFRUV+IR, the beta-corrected
SFRUV,corr exhibits systematic deviations as a function of IRX, BD and Tdust.


title:
Bi-Sobolev homeomorphisms $f$ with $Df$ and $Df^{-1}$ of low rank using
  laminates

abstract:
  Let $\Omega\subset \mathbb{R}^{n}$ be a bounded open set. Given $1\leq
m_1,m_2\leq n-2$, we construct a homeomorphism $f :\Omega\to \Omega$ that is
H\"older continuous, $f$ is the identity on $\partial \Omega$, the derivative
$D f$ has rank $m_1$ a.e.\ in $\Omega$, the derivative $D f^{-1}$ of the
inverse has rank $m_2$ a.e.\ in $\Omega$, $Df\in W^{1,p}$ and $Df^{-1}\in
W^{1,q}$ for $p<\min\{m_1+1,n-m_2\}$, $q<\min\{m_2+1,n-m_1\}$. The proof is
based on convex integration and laminates. We also show that the integrability
of the function and the inverse is sharp.


title:
Two-Dimensional Group-IV Chalcogenide Si2Te2 film: A New Quantum Spin
  Hall Insulator with Sizable Band Gap

abstract:
  Quantum spin Hall (QSH) effect is promising for achieving dissipationless
transport devices due to the robust gapless states inside insulating bulk gap.
Here, by using first-principles calculations, we discover group-IV chalcogenide
Si2Te2 film to be a 2D QSH insulator with a fundamental band gap of 0.29 eV,
which is tunable under external strain. This nontrivial topological phase stems
from band inversion between the Si-px,y and Te-px,y orbitals, demonstrated by a
single pair of topologically protected helical edge states with Dirac point
locating in the bulk gap. Notably, the characteristic properties of edge
states, such as the Fermi velocity and edge shape, can be tuned by edge
modifications. Additionally, the h-BN semiconductor is an ideal substrate for
experimental realization of 2D Si2Te2 film, without destroying its nontrivial
topology. Our works open a new route for designing topological spintronics
devices based on 2D silicon-based films.


title: BioInfoBase : A Bioinformatics Resourceome

abstract:
  Over the past decade there has been a significant growth in bioinformatics
databases, tools and resources. Although, bioinformatics is becoming more
specific, increasing the number of bioinformatics-wares has made it difficult
for researchers to find the most appropriate databases, tools or methods which
match their needs. Our coordinated effort has been planned to establish a
reference website in Bioinformatics as a public repository of tools, databases,
directories and resources annotated with contextual information and organized
by functional relevance. Within the first phase of BioInfoBase development, 22
experts in different fields of molecular biology contributed and more than 2500
records were registered, which are increasing daily. For each record submitted
to the database of website almost all related data (40 features) has been
extracted. These include information from the biological category and
subcategory to the scientific article and developer information. Searching the
query keyword(s) returns links containing the entered keyword(s) found within
the different features of the records with more weights on the title, abstract
and application fields. The search results simply provide the users with the
most informative features of the records to select the most suitable ones. The
usefulness of the returned results is ranked according to the matching score
based on the Term Frequency-Inverse Document Frequency (TF-IDF) methods.
Therefore, this search engine will screen a comprehensive index of
bioinformatics tools, databases and resources and provide the best suited
records (links) to the researchers need. The BioInfoBase resource is available
at www.bioinfobase.info.


title: The faint end of the 250 micron luminosity function at z < 0.5

abstract:
  Aims. We aim to study the 250 micron luminosity function (LF) down to much
fainter luminosities than achieved by previous efforts.
  Methods. We developed a modified stacking method to reconstruct the 250
micron LF using optically selected galaxies from the SDSS survey and Herschel
maps of the GAMA equatorial fields and Stripe 82. Our stacking method not only
recovers the mean 250 micron luminosities of galaxies that are too faint to be
individually detected, but also their underlying distribution functions.
  Results. We find very good agreement with previous measurements in the
overlapping luminosity range. More importantly, we are able to derive the LF
down to much fainter luminosities (around 25 times fainter) than achieved by
previous studies. We find strong positive luminosity evolution \propto (1 +
z)^4.89\pm1.07 and moderate negative density evolution \propto (1 +
z)^-1.02\pm0.54 over the redshift range z=[0.02, 0.5].


title:
Point-surface fusion of station measurements and satellite observations
  for mapping PM2.5 distribution in China: methods and assessment

abstract:
  Fine particulate matter (PM2.5) is associated with adverse human health
effects, and China is currently suffering from serious PM2.5 pollution. To
obtain spatially continuous ground-level PM2.5 concentrations, several models
established by point-surface fusion of ground station and satellite
observations have been developed. However, how well do these models perform at
national scale in China? Is there space to improve the estimation accuracy of
PM2.5 concentration? The contribution of this study is threefold. Firstly,
taking advantage of the newly established national monitoring network, we
develop a national-scale generalized regression neural network (GRNN) model to
estimate PM2.5 concentrations. Secondly, different assessment experiments are
undertaken in time and space, to comprehensively evaluate and compare the
performance of the widely used models. Finally, to map the yearly and seasonal
mean distribution of PM2.5 concentrations in China, a pixel-based merging
strategy is proposed. The results indicate that the conventional models (linear
regression, multiple linear regression, and semi-empirical model) do not
perform well at national scale, with cross-validation R values of 0.488~0.552
and RMSEs of 30.80~31.51 {\mu}g/m3, respectively. In contrast, the more
advanced models (geographically weighted regression, back-propagation neural
network, and GRNN) have great advantages in PM2.5 estimation, with R values
ranging from 0.610 to 0.816 and RMSEs from 20.93 to 28.68 {\mu}g/m3,
respectively. In particular, the proposed GRNN model obtains the best
performance. Furthermore, the mapped PM2.5 distribution retrieved from 3-km
MODIS aerosol optical depth (AOD) products, agrees quite well with the station
measurements. The results also show that our study has the capacity to provide
reasonable information for the global monitoring of PM2.5 pollution in China.


title: Heavy hole states in Germanium hut wires

abstract:
  Hole spins have gained considerable interest in the past few years due to
their potential for fast electrically controlled qubits. Here, we study holes
confined in Ge hut wires, a so far unexplored type of nanostructure. Low
temperature magnetotransport measurements reveal a large anisotropy between the
in-plane and out-of-plane g-factors of up to 18. Numerical simulations verify
that this large anisotropy originates from a confined wave function which is of
heavy hole character. A light hole admixture of less than 1% is estimated for
the states of lowest energy, leading to a surprisingly large reduction of the
out-of-plane g-factors. However, this tiny light hole contribution does not
influence the spin lifetimes, which are expected to be very long, even in non
isotopically purified samples.


title:
Gauge groups and matter spectra in F-theory compactifications on
  genus-one fibered Calabi-Yau 4-folds without section - hypersurface and
  double cover constructions

abstract:
  We investigate gauge theories and matter contents in F-theory
compactifications on families of genus-one fibered Calabi-Yau 4-folds lacking a
global section. To construct families of genus-one fibered Calabi-Yau 4-folds
that lack a global section, we consider two constructions: hypersurfaces in a
product of projective spaces, and double covers of a product of projective
spaces. We consider specific forms of defining equations for these genus-one
fibrations, so that genus-one fibers possess complex multiplications of
specific orders. These symmetries enable a detailed analysis of gauge theories.
$E_6$, $E_7$, and $SU(5)$ gauge groups arise in some models. Discriminant
components intersect with one another in the constructed models, and therefore,
discriminant components contain matter curves. We deduce potential matter
spectra and Yukawa couplings.


title: Unveiling the Dynamics of the Universe

abstract:
  We explore the dynamics and evolution of the Universe at early and late
times, focusing on both dark energy and extended gravity models and their
astrophysical and cosmological consequences. Modified theories of gravity not
only provide an alternative explanation for the recent expansion history of the
universe, but they also offer a paradigm fundamentally distinct from the
simplest dark energy models of cosmic acceleration. In this review, we perform
a detailed theoretical and phenomenological analysis of different modified
gravity models and investigate their consistency. We also consider the
cosmological implications of well motivated physical models of the early
universe with a particular emphasis on inflation and topological defects.
Astrophysical and cosmological tests over a wide range of scales, from the
solar system to the observable horizon, severely restrict the allowed models of
the Universe. Here, we review several observational probes -- including
gravitational lensing, galaxy clusters, cosmic microwave background temperature
and polarization, supernova and baryon acoustic oscillations measurements --
and their relevance in constraining our cosmological description of the
Universe.


title:
Reductions in Depth-integrated Picophytoplanktonic Photosynthesis Due to
  Inhibition by Ultraviolet and Photosynthetically Available Radiation: Global
  Predictions for $\textit{Prochlorococcus}$ and $\textit{Synechococcus}$

abstract:
  Phytoplankton photosynthesis in most natural waters is often inhibited by
ultraviolet (UV) and intense photosynthetically available radiation (PAR) but
the effects on ocean productivity have received little consideration aside from
polar areas subject to periodic enhanced UV-B due to depletion of stratospheric
ozone. Here we consider responses in the temperate and tropical mid-ocean
regions typically dominated by picophytoplankton including the prokaryotic
lineages, $\textit{Prochlorococcus}$ and $\textit{Synechococcus}$. Spectral
models of photosynthetic response for each lineage were constructed using model
strains cultured at different growth irradiances and temperatures. In the
model, inhibition becomes more severe once exposure exceeds a threshold (Emax)
related to repair capacity. Model parameters are presented for
$\textit{Prochlorococcus}$ adding to those previously presented for
$\textit{Synechococcus}$. The models were applied to the estimation of mid-day,
water-column photosynthesis based on an atmospheric model of spectral incident
radiation, satellite-derived spectral water transparency and sea surface
temperature. Comparing predictions integrated over the water column including
versus excluding inhibition, production was 7-28% lower due to inhibition
depending on strain and site conditions. Inhibition was consistently greater
for $\textit{Prochlorococcus}$ compared to two strains of
$\textit{Synechococcus}$. Considering only the surface mixed layer, production
was inhibited 7-73%. Weighted by lineage abundance and daily PAR exposure,
inhibition of full water column production averages around 20% for the modeled
region of the Pacific with two-thirds of the inhibition due to UV. The results
suggest more consideration is needed on inhibition effects, especially due to
UV, which are largely excluded from present models of global phytoplankton
production.


title: Compass Impurity Model of Tb Substitution in Sr2IrO4

abstract:
  We show that upon Tb substitution the interaction between the magnetic
moments on the impurity Tb$^{4+}$ ion and its surrounding Ir$^{4+}$ ions is
described by a "compass" model, i.e., Ising-like interaction favoring the
magnetic moments across each bond to align along the bond direction. Such
interaction nucleates quenched magnetic vortices near the impurities and drives
a reentrant transition out of the antiferromagnetic ordered phase at low
temperatures hence quickly suppresses the N\'eel temperature consistent with
the experiment [Phys. Rev. B \textbf{92}, 214411 (2015)]. As a by-product, we
propose that the compass model can be realized in ordered double perovskites
composed of the spin-orbital-coupled $d^{5}$ ions and the half-closed-shell
$f^{7}$ ions.


title: Enhancing HPC Security with a User-Based Firewall

abstract:
  HPC systems traditionally allow their users unrestricted use of their
internal network. While this network is normally controlled enough to guarantee
privacy without the need for encryption, it does not provide a method to
authenticate peer connections. Protocols built upon this internal network must
provide their own authentication. Many methods have been employed to perform
this authentication. However, support for all of these methods requires the HPC
application developer to include support and the user to configure and enable
these services. The user-based firewall capability we have prototyped enables a
set of rules governing connections across the HPC internal network to be put
into place using Linux netfilter. By using an operating system-level
capability, the system is not reliant on any developer or user actions to
enable security. The rules we have chosen and implemented are crafted to not
impact the vast majority of users and be completely invisible to them.


title:
Transfer matrix spectrum for cyclic representations of the 6-vertex
  reflection algebra I

abstract:
  We study the transfer matrix spectral problem for the cyclic representations
of the trigonometric 6-vertex reflection algebra associated to the
Bazhanov-Stroganov Lax operator. The results apply as well to the spectral
analysis of the lattice sine-Gordon model with integrable open boundary
conditions. This spectral analysis is developed by implementing the method of
separation of variables (SoV). The transfer matrix spectrum (both eigenvalues
and eigenstates) is completely characterized in terms of the set of solutions
to a discrete system of polynomial equations in a given class of functions.
Moreover, we prove an equivalent characterization as the set of solutions to a
Baxter's like T-Q functional equation and rewrite the transfer matrix
eigenstates in an algebraic Bethe ansatz form. In order to explain our method
in a simple case, the present paper is restricted to representations containing
one constraint on the boundary parameters and on the parameters of the
Bazhanov-Stroganov Lax operator. In a next article, some more technical tools
(like Baxter's gauge transformations) will be introduced to extend our approach
to general integrable boundary conditions.

categories: math-ph cond-mat.stat-mech hep-th math.MP nlin.SI


title: On the growth constant for square-lattice self-avoiding walks

abstract:
  The growth constant for two-dimensional self-avoiding walks on the honeycomb
lattice was conjectured by Nienhuis in 1982, and since that time the
corresponding results for the square and triangular lattices have been sought.
For the square lattice, a possible conjecture was advanced by one of us (AJG)
more than 20 years ago, based on the six significant digit estimate available
at the time. This estimate has improved by a further six digits over the
intervening decades, and the conjectured value continued to agree with the
increasingly precise estimates. We discuss the three most successful methods
for estimating the growth constant, including the most recently developed
Topological Transfer-Matrix method, due to another of us (JLJ). We show this to
be the most computationally efficient of the three methods, and by
parallelising the algorithm we have estimated the growth constant significantly
more precisely, incidentally ruling out the conjecture, which fails in the 12th
digit. Our new estimate of the growth constant is $$\mu(\mathrm{square}) =
2.63815853032790\, (3).$$


title: Triple-resonant Brillouin light scattering in magneto-optical cavities

abstract:
  An enhancement in Brillouin light scattering of optical photons with magnons
is demonstrated in magneto-optical whispering gallery mode resonators tuned to
a triple resonance point. This occurs when both the input and output optical
modes are resonant with those of the whispering gallery resonator, with a
separation given by the ferromagnetic resonance (FMR) frequency. The
identification and excitation of specific optical modes allows us to gain a
clear understanding of the mode-matching conditions. A selection rule due to
wavevector matching leads to an intrinsic single-sideband excitation. Strong
suppression of one sideband is essential for one-to-one frequency mapping in
coherent optical-to-microwave conversion.


title: A Birthday Repetition Theorem and Complexity of Approximating Dense CSPs

abstract:
  A $(k \times l)$-birthday repetition $\mathcal{G}^{k \times l}$ of a
two-prover game $\mathcal{G}$ is a game in which the two provers are sent
random sets of questions from $\mathcal{G}$ of sizes $k$ and $l$ respectively.
These two sets are sampled independently uniformly among all sets of questions
of those particular sizes. We prove the following birthday repetition theorem:
when $\mathcal{G}$ satisfies some mild conditions, $val(\mathcal{G}^{k \times
l})$ decreases exponentially in $\Omega(kl/n)$ where $n$ is the total number of
questions. Our result positively resolves an open question posted by Aaronson,
Impagliazzo and Moshkovitz (CCC 2014).
  As an application of our birthday repetition theorem, we obtain new
fine-grained hardness of approximation results for dense CSPs. Specifically, we
establish a tight trade-off between running time and approximation ratio for
dense CSPs by showing conditional lower bounds, integrality gaps and
approximation algorithms. In particular, for any sufficiently large $i$ and for
every $k \geq 2$, we show the following results:
  - We exhibit an $O(q^{1/i})$-approximation algorithm for dense Max $k$-CSPs
with alphabet size $q$ via $O_k(i)$-level of Sherali-Adams relaxation.
  - Through our birthday repetition theorem, we obtain an integrality gap of
$q^{1/i}$ for $\tilde\Omega_k(i)$-level Lasserre relaxation for fully-dense Max
$k$-CSP.
  - Assuming that there is a constant $\epsilon > 0$ such that Max 3SAT cannot
be approximated to within $(1-\epsilon)$ of the optimal in sub-exponential
time, our birthday repetition theorem implies that any algorithm that
approximates fully-dense Max $k$-CSP to within a $q^{1/i}$ factor takes
$(nq)^{\tilde \Omega_k(i)}$ time, almost tightly matching the algorithmic
result based on Sherali-Adams relaxation.


title: Decision and function problems based on boson sampling

abstract:
  Boson sampling is a mathematical problem that is strongly believed to be
intractable for classical computers, whereas passive linear interferometers can
produce samples efficiently. So far, the problem remains a computational
curiosity, and the possible usefulness of boson-sampling devices is mainly
limited to the proof of quantum supremacy. The purpose of this work is to
investigate whether boson sampling can be used as a resource of decision and
function problems that are computationally hard, and may thus have
cryptographic applications. After the definition of a rather general
theoretical framework for the design of such problems, we discuss their
solution by means of a brute-force numerical approach, as well as by means of
non-boson samplers. Moreover, we estimate the sample sizes required for their
solution by passive linear interferometers, and it is shown that they are
independent of the size of the Hilbert space.


title:
The quasiequational theory of relational lattices, in the pure lattice
  signature (embeddability into relational lattices is undecidable)

abstract:
  The natural join and the inner union operations combine relations of a
database. Tropashko and Spight realized that these two operations are themeet
and join operations in a class of lattices, known by now as the relational
lattices. They proposed then lattice theory as an algebraic approach to
thetheory of databases alternative to the relational algebra. Litak et al.
proposed an axiomatization of relational lattices over the signature that
extends thepure lattice signature with a constant and argued that the
quasiequational theory of relational lattices over this extended signature is
undecidable.We prove in this paper that embeddability is undecidable for
relational lattices. More precisely, it is undecidable whether a finite
subdirectly-irreduciblelattice can be embedded into a relational lattice. Our
proof is a reduction from the coverability problem of a multimodal frame by a
universal product frameand, indirectly, from the representability problem for
relation algebras. As corollaries we obtain the following results: the
quasiequational theoryof relational lattices over the pure lattice signature is
undecidable and has no finite base; there is a quasiequation over the pure
lattice signature which holds in all the finite relational lattices but fails
in an infinite relational lattice.


title: Gauge invariant flow equation

abstract:
  We propose a closed gauge-invariant functional flow equation for Yang-Mills
theories and quantum gravity that only involves one macroscopic gauge field or
metric. It is based on a projection on physical and gauge fluctuations.
Deriving this equation from a functional integral we employ the freedom in the
precise choice of the macroscopic field and the effective average action in
order to realize a closed and simple form of the flow equation.


title: Critical SQG in bounded domains

abstract:
  We consider the critical dissipative SQG equation in bounded domains, with
the square root of the Dirichlet Laplacian dissipation. We prove global a
priori interior $C^{\alpha}$ and Lipschitz bounds for large data.


title: Complexity Theory and its Applications in Linear Quantum Optics

abstract:
  This thesis is intended in part to summarize and also to contribute to the
newest developments in passive linear optics that have resulted, directly or
indirectly, from the somewhat shocking discovery in 2010 that the BosonSampling
problem is likely hard for a classical computer to simulate. In doing so, I
hope to provide a historic context for the original result, as well as an
outlook on the future of technology derived from these newer developments. An
emphasis is made in each section to provide a broader conceptual framework for
understanding the consequences of each result in light of the others. This
framework is intended to be comprehensible even without a deep understanding of
the topics themselves.
  The first three chapters focus more closely on the BosonSampling result
itself, seeking to understand the computational complexity aspects of passive
linear optical networks, and what consequences this may have. Some effort is
spent discussing a number of issues inherent in the BosonSampling problem that
limit the scope of its applicability, and that are still active topics of
research. Finally, we describe two other linear optical settings that inherit
the same complexity as BosonSampling. The final chapters focus on how an
intuitive understanding of BosonSampling has led to developments in optical
metrology and other closely related fields. These developments suggest the
exciting possibility that quantum sensors may be viable in the next few years
with only marginal improvements in technology. Lastly, some open problems are
presented which are intended to lay out a course for future research that would
allow for a more complete picture of the scalability of the architecture
developed in these chapters.


title: Negativity spectrum of one-dimensional conformal field theories

abstract:
  The partial transpose $\rho_A^{T_2}$ of the reduced density matrix $\rho_A$
is the key object to quantify the entanglement in mixed states, in particular
through the presence of negative eigenvalues in its spectrum. Here we derive
analytically the distribution of the eigenvalues of $\rho_A^{T_2}$, that we dub
negativity spectrum, in the ground sate of gapless one-dimensional systems
described by a Conformal Field Theory (CFT), focusing on the case of two
adjacent intervals. We show that the negativity spectrum is universal and
depends only on the central charge of the CFT, similarly to the entanglement
spectrum. The precise form of the negativity spectrum depends on whether the
two intervals are in a pure or mixed state, and in both cases, a dependence on
the sign of the eigenvalues is found. This dependence is weak for bulk
eigenvalues, whereas it is strong at the spectrum edges. We also investigate
the scaling of the smallest (negative) and largest (positive) eigenvalues of
$\rho_A^{T_2}$. We check our results against DMRG simulations for the critical
Ising and Heisenberg chains, and against exact results for the harmonic chain,
finding good agreement for the spectrum, but showing that the smallest
eigenvalue is affected by very large scaling corrections.


title:
Bayesian variable selection in high dimensional problems without
  assumptions on prior model probabilities

abstract:
  We consider the problem of variable selection in linear models when $p$, the
number of potential regressors, may exceed (and perhaps substantially) the
sample size $n$ (which is possibly small).


title: Bad groups in the sense of Cherlin

abstract:
  There exists no bad group (in the sense of Gregory Cherlin), namely any
simple group of Morley rank 3 is isomorphic to PSL2(K) for an algebraically
closed field K.


title: Ulrich bundles on blowups

abstract:
  We construct an Ulrich bundle on the blowup at a point when the original
variety is embedded by a sufficiently positive linear system and carries an
Ulrich bundle. In particular, we describe the relation between special Ulrich
bundles on the blown-up surfaces and the original surfaces.


title:
The effects of magnetic-field geometry on longitudinal oscillations of
  solar prominences: Cross-sectional area variation for thin tubes

abstract:
  Solar prominences are subject to both field-aligned (longitudinal) and
transverse oscillatory motions, as evidenced by an increasing number of
observations. Large-amplitude longitudinal motions provide valuable information
on the geometry of the filament-channel magnetic structure that supports the
cool prominence plasma against gravity. Our pendulum model, in which the
restoring force is the gravity projected along the dipped field lines of the
magnetic structure, best explains these oscillations. However, several factors
can influence the longitudinal oscillations, potentially invalidating the
pendulum model. The aim of this work is to study the influence of large-scale
variations in the magnetic field strength along the field lines, i.e.,
variations of the cross-sectional area along the flux tubes supporting
prominence threads. We studied the normal modes of several flux tube
configurations, using linear perturbation analysis, to assess the influence of
different geometrical parameters on the oscillation properties. We found that
the influence of the symmetric and asymmetric expansion factors on longitudinal
oscillations is small.}{We conclude that the longitudinal oscillations are not
significantly influenced by variations of the cross-section of the flux tubes,
validating the pendulum model in this context.


title:
Remarks on the static potential driven by vacuum nonlinearities in $D=3$
  models

abstract:
  Within the framework of the gauge-invariant, but path-dependent, variables
formalism, we study the manifestations of vacuum electromagnetic nonlinearities
in $D=3$ models. For this we consider both generalized Born-Infeld and
Pagels-Tomboulis-like electrodynamics, as well as, an Euler-Heisenberg-like
electrodynamics. We explicitly show that generalized Born-Infeld and
Pagels-Tomboulis-like electrodynamics are equivalent, where the static
potential profile contains a long-range (${\raise0.5ex\hbox{$\scriptstyle
1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle {{r^2}}$}}$-type)
correction to the Coulomb potential. Interestingly enough, for an
Euler-Heisenberg-like electrodynamics the interaction energy contains a linear
potential, leading to the confinement of static charges.


title:
On uniqueness of solutions to martingale problems --- counterexamples
  and sufficient criteria

abstract:
  The dynamics of a Markov process are often specified by its infinitesimal
generator or, equivalently, its symbol. This paper contains examples of
analytic symbols which do not determine the law of the corresponding Markov
process uniquely. These examples also show that the law of a polynomial process
is not necessarily determined by its generator. On the other hand, we show that
a combination of smoothness of the symbol and ellipticity warrants uniqueness
in law. The proof of this result is based on proving stability of univariate
marginals relative to some properly chosen distance.


title:
Nonradiative limitations to plasmon propagation in chains of metallic
  nanoparticles

abstract:
  We investigate the collective plasmonic modes in a chain of metallic
nanoparticles that are coupled by near-field interactions. The size- and
momentum-dependent nonradiative Landau damping and radiative decay rates are
calculated analytically within an open quantum system approach. These decay
rates determine the excitation propagation along the chain. In particular, the
behavior of the radiative decay rate as a function of the plasmon wavelength
leads to a transition from an exponential decay of the collective excitation
for short distances to an algebraic decay for large distances. Importantly, we
show that the exponential decay is of a purely nonradiative origin. Our
transparent model enables us to provide analytical expressions for the
polarization-dependent plasmon excitation profile along the chain and for the
associated propagation length. Our theoretical analysis constitutes an
important step in the quest for the optimal conditions for plasmonic
propagation in nanoparticle chains.


title: Bayesian isochrone fitting and stellar ages

abstract:
  Stellar evolution theory has been extraordinarily successful at explaining
the different phases under which stars form, evolve and die. While the
strongest constraints have traditionally come from binary stars, the advent of
asteroseismology is bringing unique measures in well-characterised stars. For
stellar populations in general, however, only photometric measures are usually
available, and the comparison with the predictions of stellar evolution theory
have mostly been qualitative. For instance, the geometrical shapes of
isochrones have been used to infer ages of coeval populations, but without any
proper statistical basis. In this chapter we provide a pedagogical review on a
Bayesian formalism to make quantitative inferences on the properties of single,
binary and small ensembles of stars, including unresolved populations. As an
example, we show how stellar evolution theory can be used in a rigorous way as
a prior information to measure the ages of stars between the ZAMS and the
Helium flash, and their uncertainties, using photometric data only.

categories: astro-ph.GA astro-ph.IM physics.hist-ph stat.AP


title:
Tomography and Purification of the Temporal-Mode Structure of Quantum
  Light

abstract:
  High-dimensional quantum information processing promises capabilities beyond
the current state of the art, but addressing individual information-carrying
modes presents a significant experimental challenge. Here we demonstrate
effective high-dimensional operations in the time-frequency domain of
non-classical light. We generate heralded photons with tailored temporal-mode
structures through ultrafast pulse shaping of a parametric downconversion pump.
We then implement a quantum pulse gate, enabled by dispersion-engineered
sum-frequency generation, to project onto programmable temporal modes,
reconstructing the quantum state in seven dimensions. We also manipulate the
time-frequency structure by selectively removing temporal modes, explicitly
demonstrating the effectiveness of engineered nonlinear processes for
mode-selective manipulation of quantum states.


title: Rates, Flux Densities, and Spectral Indices of Meteor Radio Afterglows

abstract:
  Using the narrowband all-sky imager mode of the LWA1 we have now detected 30
transients at 25.6 MHz, 1 at 34 MHz, and 93 at 38.0 MHz. While we have only
optically confirmed that 37 of these events are radio afterglows from meteors,
evidence suggests that most, if not all, are. Using the beam-forming mode of
the LWA1 we have also captured the broadband spectra between 22.0 and 55.0 MHz
of four events. We compare the smooth, spectral components of these four events
and fit the frequency dependent flux density to a power law, and find that the
spectral index is time variable, with the spectrum steepening over time for
each meteor afterglow. Using these spectral indices along with the narrow band
flux density measurements of the 123 events at 25.6 and 38 MHz, we predict the
expected flux densities and rates for meteor afterglows potentially observable
by other low frequency radio telescopes.


title:
Scalar field dark energy with a minimal coupling in a spherically
  symmetric background

abstract:
  Dark energy models and modified gravity theories have been actively studied
and the behaviors in the solar system have been also carefully investigated in
a part of the models. However, the isotropic solutions of the field equations
in the simple models of dark energy, e.g. quintessence model without matter
coupling, have not been well investigated. One of the reason would be the
nonlinearity of the field equations. In this paper, a method to evaluate the
solution of the field equations is constructed, and it is shown that there is a
model that can easily pass the solar system tests, whereas, there is also a
model that is constrained from the solar system tests.


title:
Blow-up rate of the scalar curvature along the conical K\"ahler-Ricci
  flow with finite time singularities

abstract:
  We investigate the scalar curvature behavior along the normalized conical
K\"ahler-Ricci flow $\omega_t$, which is the conic version of the normalized
K\"ahler-Ricci flow, with finite maximal existence time $T<\infty $. We prove
that the scalar curvature of $\omega_t$ is bounded from above by $C/(T-t)^2$
under the existence of a contraction associated to the limiting cohomology
class $[\omega_T]$. This generalizes Z. Zhang's work to the conic case.


title: On a classification of fat bundles over compact homogeneous spaces

abstract:
  This article deals with fat bundles. Berard-Bergery classified all
homogeneous bundles of that type. We ask a question of a possibility to
generalize his description in the case of arbitrary G-structures over
homogeneous spaces. We obtain necessary conditions for the existence of such
bundles. These conditions yield a kind of classification of fat bundles
associated with G-structures over compact homogeneous spaces provided that the
connection in a G-structure is canonical.


title:
The gamma-ray source AGL J2241+4454 as the possible counterpart of MWC
  656

abstract:
  The AGILE satellite discovered the transient source AGL J2241+4454 in 2010
which triggered the study of the associated field allowing for the discovery of
the first Be/black hole binary system: MWC 656. This binary was suggested to be
the counterpart of AGL J2241+4454, but this is still not a firm association. In
this work we explore the archival AGILE and Fermi/LAT data in order to find
more transient events originating in the field of AGL J2241+4454 and address
the possibility to link them to the accretion/ejection processes of MWC 656. We
found a total of 9 other transient events with AGILE compatible with the
position of AGL J2241+4454, besides the one from 2010. We folded this events
with the period of the binary system and we did not find significant results
that allow us to associate the gamma-ray activity to any particular orbital
phase. By stacking the 10 transient events we obtained a spectrum that extends
between 100 MeV and 1 GeV, and we fitted it with a power law with photon index
{\Gamma} = 2.3 +/- 0.2. We searched into the Fermi /LAT data in order to
complement the gamma-ray information provided by AGILE but no significant
results arose. In order to investigate this apparent contradiction between the
two gamma-ray telescopes, we studied the exposure of the field of AGL
J2241+4454 in both instruments finding significant differences. In particular,
AGILE exposed for longer time and at lower off-axis angle distance the field of
AGL J2241+4454. This fact, together with the energy dependent sensitivity of
both instruments, and the soft spectrum found in the stacking analysis, might
explain why AGILE observed the transient events not seen by Fermi/LAT.


title: Non-vanishing of fundamental Fourier coefficients of paramodular forms

abstract:
  We prove that paramodular newforms of odd square-free level have infinitely
many non-zero fundamental Fourier coefficients.


title:
Positive Energy Unitary Irreducible Representations of the Superalgebra
  osp(1|8,R)

abstract:
  We continue the study of positive energy (lowest weight) unitary irreducible
representations of the superalgebras osp(1|2n,R). We present the full list of
these UIRs. We give the Proof of the case osp(1|8,R).


title:
Impacts of fragmented accretion streams onto Classical T Tauri Stars: UV
  and X-ray emission lines

abstract:
  Context. The accretion process in Classical T Tauri Stars (CTTSs) can be
studied through the analysis of some UV and X-ray emission lines which trace
hot gas flows and act as diagnostics of the post-shock downfalling plasma. In
the UV band, where higher spectral resolution is available, these lines are
characterized by rather complex profiles whose origin is still not clear.
  Aims. We investigate the origin of UV and X-ray emission at impact regions of
density structured (fragmented) accretion streams.We study if and how the
stream fragmentation and the resulting structure of the post-shock region
determine the observed profiles of UV and X-ray emission lines.
  Methods. We model the impact of an accretion stream consisting of a series of
dense blobs onto the chromosphere of a CTTS through 2D MHD simulations. We
explore different levels of stream fragmentation and accretion rates. From the
model results, we synthesize C IV (1550 {\AA}) and OVIII (18.97 {\AA}) line
profiles.
  Results. The impacts of accreting blobs onto the stellar chromosphere produce
reverse shocks propagating through the blobs and shocked upflows. These
upflows, in turn, hit and shock the subsequent downfalling fragments. As a
result, several plasma components differing for the downfalling velocity,
density, and temperature are present altoghether. The profiles of C IV doublet
are characterized by two main components: one narrow and redshifted to speed
$\approx$ 50 km s$^{-1}$ and the other broader and consisting of subcomponents
with redshift to speed in the range 200 $\approx$ 400 km s$^{-1}$. The profiles
of OVIII lines appear more symmetric than C IV and are redshifted to speed
$\approx$ 150 km s$^{-1}$.
  Conclusions. Our model predicts profiles of C IV line remarkably similar to
those observed and explains their origin in a natural way as due to stream
fragmentation.


title: Intersecting free subgroups in free products of left ordered groups

abstract:
  A conjecture of Dicks and the author on rank of the intersection of
factor-free subgroups in free products of groups is proved for the case of left
ordered groups.


title: Solutions in the (1/2,0)+(0,1/2) Representation of the Lorentz Group

abstract:
  I present explicit examples of generalizations in relativistic quantum
mechanics. First of all, I discuss the generalized spin-1/2 equations for
neutrinos. They have been obtained by means of the Gersten-Sakurai method for
derivations of arbitrary-spin relativistic equations. Possible physical
consequences are discussed. Next, it is easy to check that both Dirac algebraic
equation $Det (\hat p - m) =0$ and $Det (\hat p + m) =0$ for $u-$ and $v-$
4-spinors have solutions with $p_0= \pm E_p =\pm \sqrt{{\bf p}^2 +m^2}$. The
same is true for higher-spin equations. Meanwhile, every book considers the
equality $p_0=E_p$ for both $u-$ and $v-$ spinors of the $(1/2,0)\oplus
(0,1/2))$ representation only, thus applying the Dirac-Feynman-Stueckelberg
procedure for elimination of the negative-energy solutions. The recent work by
Ziino (and, independently, the articles of several others) show that the Fock
space can be doubled. We re-consider this possibility on the quantum field
level for $S=1/2$ particles. The third example is: we postulate the
non-commutativity of 4-momenta, and we derive the mass splitting in the Dirac
equation. Some applications are discussed.


title: Motivic Realizations of Singularity Categories and Vanishing Cycles

abstract:
  In this paper we establish a precise comparison between vanishing cycles and
the singularity category of Landau-Ginzburg models over a complete discrete
valuation ring. By using noncommutative motives, we first construct a motivic
$\ell$-adic realization functor for dg-categories. Our main result, then
asserts that, given a Landau-Ginzburg model over a complete discrete valuation
ring with potential induced by a uniformizer, the $\ell$-adic realization of
its singularity category is given by the inertia-invariant part of vanishing
cohomology. We also prove a functorial and $\infty$-categorical version of
Orlov's comparison theorem between the derived category of singularities and
the derived category of matrix factorizations for a Landau-Ginzburg model over
a noetherian regular local ring.


title: Variational data assimilation for transient blood flow simulations

abstract:
  Several cardiovascular diseases are caused from localised abnormal blood flow
such as in the case of stenosis or aneurysms. Prevailing theories propose that
the development is caused by abnormal wall-shear stress in focused areas.
Computational fluid mechanics have arisen as a promising tool for a more
precise and quantitative analysis, in particular because the anatomy is often
readily available even by standard imaging techniques such as magnetic
resolution and computed tomography angiography. However, computational fluid
mechanics rely on accurate boundary conditions which is difficult to obtain. In
this paper we address the problem of recovering high resolution information
from noisy, low-resolution measurements of blood flow using variational data
assimilation (also known as 4DVar). We show that accurate flow reconstruction
is obtained with proper regularisation even in the presence of significant
noise and for a range of regularisation parameters spanning orders of
magnitude. Numerical experiments are performed in both 2D and 3D and with
pulsatile flow relevant for physiological flow in cerebral aneurysms.


title: The middle hedgehog of a planar convex body

abstract:
  A convexity point of a convex body is a point with the property that the
union of the body and its reflection in the point is convex. It is proved that
in the plane a typical convex body (in the sense of Baire category) has
infinitely many convexity points. The proof makes use of the `middle hedgehog'
of a planar convex body $K$, which is the curve formed by the midpoints of all
affine diameters of $K$. The stated result follows from the fact that for a
typical planar convex body the convex hull of the middle hedgehog has
infinitely many exposed points.


title: Merging the A- and Q-spectral theories

abstract:
  Let $G$ be a graph with adjacency matrix $A\left( G\right) $, and let
$D\left( G\right) $ be the diagonal matrix of the degrees of $G.$ The signless
Laplacian $Q\left( G\right) $ of $G$ is defined as $Q\left( G\right) :=A\left(
G\right) +D\left( G\right) $.
  Cvetkovi\'{c} called the study of the adjacency matrix the $A$%
\textit{-spectral theory}, and the study of the signless Laplacian--the
$Q$\textit{-spectral theory}. During the years many similarities and
differences between these two theories have been established. To track the
gradual change of $A\left( G\right) $ into $Q\left( G\right) $ in this paper it
is suggested to study the convex linear combinations $A_{\alpha }\left(
G\right) $ of $A\left( G\right) $ and $D\left( G\right) $ defined by \[
A_{\alpha}\left( G\right) :=\alpha D\left( G\right) +\left( 1-\alpha\right)
A\left( G\right) \text{, \ \ }0\leq\alpha\leq1. \] This study sheds new light
on $A\left( G\right) $ and $Q\left( G\right) $, and yields some surprises, in
particular, a novel spectral Tur\'{a}n theorem. A number of challenging open
problems are discussed.


title:
Self-consistent Keldysh approach to quenches in weakly interacting
  Bose-Hubbard model

abstract:
  We present a non-equilibrium Green's functional approach to study the
dynamics following a quench in weakly interacting Bose Hubbard model (BHM). The
technique is based on the self-consistent solution of a set of equations which
represents a particular case of the most general set of Hedin's equations for
the interacting single-particle Green's function. We use the ladder
approximation as a skeleton diagram for the two-particle scattering amplitude
useful, through the self-energy in the Dyson equation, for finding the
interacting single-particle Green's function. This scheme is then implemented
numerically by a parallelized code. We exploit this approach to study the
correlation propagation after a quench in the interaction parameter, for one
(1D) and two (2D) dimensions. In particular, we show how our approach is able
to recover the crossover from ballistic to diffusive regime by increasing the
boson-boson interaction. Finally we also discuss the role of a thermal initial
state on the dynamics both for 1D and 2D Bose Hubbard models, finding that
surprisingly at high temperature a ballistic evolution is restored.


title: Gauging Unbroken Symmetries in F-theory

abstract:
  F-theory attempts to include all U-dualities manifestly. Unlike its T-dual
manifest partner, which is based on string current algebra, F-theory is based
on higher dimensional brane current algebra. Like the T-dual manifest theory,
which has $O(D-1,1)^2$ unbroken symmetry, the F-theory vacuum also enjoys
certain symmetries ("$H$"). One of its important and exotic properties is that
worldvolume indices are also spacetime indices. This makes the global brane
current algebra incompatible with $H$ symmetry currents. The solution is to
introduce worldvolume covariant derivatives, which depend on the $H$
coordinates even in a "flat" background. We will also give as an explicit
example the 5-brane case.


title: Occurrence graphs of patterns in permutations

abstract:
  We define the \emph{occurrence graph} $G_p(\pi$) of a pattern $p$ in a
permutation $\pi$ as the graph with the occurrences of $p$ in $\pi$ as vertices
and edges between the vertices if the occurrences differ by exactly one
element. We then study properties of these graphs. The main theorem in this
paper is that every \emph{hereditary property} of graphs gives rise to a
\emph{permutation class}.


title: Dynamics of students' epistemological framing in group problem solving

abstract:
  Many studies have investigated students' epistemological framing when solving
physics problems. Framing supports students' problem solving as they decide
what knowledge to employ and the necessary steps to solve the problem. Students
may frame the same problem differently and take alternate paths to a correct
solution. When students work in group settings, they share and discuss their
framing to decide how to proceed in problem solving as a whole group. In this
study, we investigate how groups of students negotiate their framing and frame
shifts in group problem solving.


title:
A non-variational approach to the existence of nonzero positive
  solutions for elliptic systems

abstract:
  We provide new results on the existence of nonzero positive weak solutions
for a class of second order elliptic systems. Our approach relies on a combined
use of iterative techniques and classical fixed point index. Some examples are
presented to illustrate the theoretical results.


title:
Salient Region Detection and Segmentation in Images using Dynamic Mode
  Decomposition

abstract:
  Visual Saliency is the capability of vision system to select distinctive
parts of scene and reduce the amount of visual data that need to be processed.
The presentpaper introduces (1) a novel approach to detect salient regions by
considering color and luminance based saliency scores using Dynamic Mode
Decomposition (DMD), (2) a new interpretation to use DMD approach in static
image processing. This approach integrates two data analysis methods: (1)
Fourier Transform, (2) Principle Component Analysis.The key idea of our work is
to create a color based saliency map. This is based on the observation
thatsalient part of an image usually have distinct colors compared to the
remaining portion of the image. We have exploited the power of different color
spaces to model the complex and nonlinear behavior of human visual system to
generate a color based saliency map. To further improve the effect of final
saliency map, weutilized luminance information exploiting the fact that human
eye is more sensitive towards brightness than color.The experimental results
shows that our method based on DMD theory is effective in comparison with
previous state-of-art saliency estimation approaches. The approach presented in
this paperis evaluated using ROC curve, F-measure rate, Precision-Recall rate,
AUC score etc.


title: A topological conjugacy of invariant flows on some class of Lie groups

abstract:
  The aim of this paper is to give a condition to topological conjugacy of
invariant flows in an Lie group $G$ which its Lie algebra $\mathfrak{g}$ is
associative algebra or semisimple. In fact, we show that if two dynamical
system on $G$ are hyperbolic, then they are topological conjugate.


title: A new view on quantum electrodynamics

abstract:
  We analyze the equations of quantum electrodynamics and establish that the
electron must be described by two bispinors that satisfy two mutually connected
Dirac equations. The equations of the electronic and electromagnetic fields are
reformulated in terms of c-numbers, which enables one to elucidate the
structure of the electron. Although the equations obtained allow only for
numerical solution, some characteristics of the electron, in particular its
size, can be found at this stage. It is shown also that the Dirac equation
should, instead of the mass of the electron, contain a combination involving
the electron Compton wavelength. In this case the equations obtained can be
used not only for the description of the electron but also for the description
of other leptons, which will allow one to find the mass spectrum of leptons.


title:
On ergodic states, spontaneous symmetry breaking and the Bogoliubov
  quasi-averages

abstract:
  It is shown that Bogoliubov quasi-averages select the pure or ergodic states
in the ergodic decomposition of the thermal (Gibbs) state. Our examples include
quantum spin systems and many-body boson systems. As a consequence, we
elucidate the problem of equivalence between Bose-Einstein condensation and the
quasi-average spontaneous symmetry breaking (SSB) discussed for continuous
boson systems. The multi-mode extended van den Berg-Lewis-Pul\'{e} condensation
of type III demonstrates that the only physically reliable quantities are those
that defined by Bogoliubov quasi-averages.


title:
Data Dissemination using Instantly Decodable Binary Codes in Fog-Radio
  Access Networks

abstract:
  Consider a device-to-device (D2D) fog-radio access network wherein a set of
devices are required to store a set of files. Each device is connected to a
subset of the cloud data centers and thus possesses a subset of the data. This
paper investigates the problem of disseminating all files among the devices
while reducing the total time of communication, i.e., the completion time,
using instantly decodable network coding (IDNC). While previous studies on the
use of IDNC in D2D systems assume a fully connected communication network, this
paper tackles the more realistic scenario of a partially connected network in
which devices can only target devices in their transmission range. The paper
first formulates the optimal joint optimization of selecting the transmitting
device(s) and the file combination(s) and exhibits its intractability. The
completion time is approximated using the celebrated decoding delay approach by
deriving the relationship between the quantities in a partially connected
network. The paper introduces the cooperation graph and demonstrates that the
relaxed problem is equivalent to a maximum weight clique problem over the newly
designed graph wherein the weights are obtained by solving a similar problem on
the local IDNC graphs. Extensive simulations reveal that the proposed solution
provides noticeable performance enhancement and outperforms previously proposed
IDNC-based schemes.


title:
Retrospective Causal Inference with Machine Learning Ensembles: An
  Application to Anti-Recidivism Policies in Colombia

abstract:
  We present new methods to estimate causal effects retrospectively from micro
data with the assistance of a machine learning ensemble. This approach
overcomes two important limitations in conventional methods like regression
modeling or matching: (i) ambiguity about the pertinent retrospective
counterfactuals and (ii) potential misspecification, overfitting, and otherwise
bias-prone or inefficient use of a large identifying covariate set in the
estimation of causal effects. Our method targets the analysis toward a well
defined ``retrospective intervention effect'' (RIE) based on hypothetical
population interventions and applies a machine learning ensemble that allows
data to guide us, in a controlled fashion, on how to use a large identifying
covariate set. We illustrate with an analysis of policy options for reducing
ex-combatant recidivism in Colombia.


title:
Quantum Drinfeld Modules I: Quantum Modular Invariant and Hilbert Class
  Fields

abstract:
  This is the first of a series of two papers in which we present a solution to
Manin's Real Multiplication program -- an approach to Hilbert's 12th problem
for real quadratic extensions of $\mathbb{Q}$ -- in positive characteristic,
using quantum analogs of the exponential function and the modular invariant. In
this first paper, we treat the problem of Hilbert class field generation. If
$k=\mathbb{F}_{q}(T)$ and $k_{\infty}$ is the analytic completion of $k$, we
introduce the quantum modular invariant \[ j^{\rm qt}: k_{\infty}\multimap
k_{\infty}\] as a multivalued, modular invariant function. Then if
$K=k(f)\subset k_{\infty}$ is a real quadratic extension of $k$ where $f$ is a
quadratic unit, we show that the Hilbert class field $H_{\mathcal{O}_{K}}$
(associated to $\mathcal{O}_{K}=$ integral closure of $\mathbb{F}_{q}[T]$ in
$K$) is generated over $K$ by the product of the multivalues of $j^{\rm
qt}(f)$.


title:
Stable manifolds for a class of degenerate evolution equations and
  exponential decay of kinetic shocks

abstract:
  We construct stable manifolds for a class of degenerate evolution equations
including the steady Boltzmann equation, establishing in the process
exponential decay of associated kinetic shock and boundary layers to their
limiting equilibrium states. Our analysis is from a classical dynamical systems
point of view, but with a number of interesting modifications to accomodate
ill-posedness with respect to the Cauchy problem of the underlying evolution
equation.


title: Investigating the free-floating planet mass by Euclid observations

abstract:
  The detection of anomalies in gravitational microlensing events is nowadays
one of the main goals among the microlensing community. In the case of
single-lens events, these anomalies can be caused by the finite source effects,
that is when the source disk size is not negligible, and by the Earth rotation
around the Sun (the so-called parallax effect). The finite source and parallax
effects may help to define the mass of the lens, uniquely. Free-floating
planets (FFPs) are extremely dim objects, and gravitational microlensing
provides at present the exclusive method to investigate these bodies. In this
work, making use of a synthetic population algorithm, we study the possibility
of detecting the finite source and parallax effects in simulated microlensing
events caused by FFPs towards the Galactic bulge, taking into consideration the
capabilities of the space-based Euclid telescope. We find a significant
efficiency for detecting the parallax effect in microlensing events with
detectable finite source effect, that turns out to be about 51% for mass
function index .


title: Scattering of W and Z Bosons at High-Energy Lepton Colliders

abstract:
  We present a new study of quasi-elastic $W$ and $Z$ scattering processes in
high-energy $e^+e^-$ collisions, based on and extrapolating the low-energy
effective theory which extends the Standard Model with a 125 GeV Higgs boson.
Besides parameterizing deviations in terms of the dimension-8 operators that
arise in the effective theory, we also study simplified models of new physics
in $W/Z$ scattering in terms of scalar and tensor resonance multiplets. The
high-energy asymptotics of all models is regulated by a universal unitarization
procedure. This enables us to provide benchmark scenarios which can be
meaningfully evaluated off-shell and in exclusive event samples, and to
determine the sensitivity of an $e^+e^-$ collider to the model parameters. We
analyze the longitudinal vector boson scattering modes, where we optimize the
cuts for the fiducial cross section for different collider scenarios. Here, we
choose energy stages of 1.0, 1.4 and 3 TeV, as motivated by the extendability
of the ILC project and the staging scenario of the CLIC project.


title: Filament tension and phase-locked drift of meandering scroll waves

abstract:
  Rotating scroll waves are self-organising patterns which are found in many
oscillating or excitable systems. Here we show that quasi-periodic (meandering)
scroll waves, which include the rotors that organise cardiac arrhythmias,
exhibit filament tension when averaged over the meander cycle. With strong
filament curvature or medium thickness gradients, however, scroll wave dynamics
are governed by phase-locked drift instead of filament tension. Our results are
validated in computational models of cycloidal meander and a cardiac tissue
model with linear core.


title:
The impact of neutral impurity concentration on charge drift mobility in
  germanium

abstract:
  We reported a new result of the neutral impurity scattering of holes that has
impact on the charge drift mobility in high purity p-type germanium crystals at
77 Kelvin. The charge carrier concentration, mobility and resistivity are
measured by Hall Effect system at 77 Kelvin. We investigated the contribution
to the total charge drift mobility from ionized impurity scattering, lattice
scattering, and neutral impurity scattering with the best theoretical models
and experimental data. Several samples with measured Hall mobility from the
grown crystals are used for this investigation. With the measured Hall mobility
and ionized impurity concentration as well as the theoretical models, we
calculated the neutral impurity concentration by the Matthiessen's rule. As a
result, the distributions of the neutral impurity concentrations with respect
to the radius of the crystals are obtained. Consequently, we demonstrated that
neutral impurity scattering is a significant contribution to the charge drift
mobility, which has dependence on the concentration of neutral impurities in a
given germanium crystal.


title:
A sharp integral inequality for the dyadic maximal operator and a
  related stability result

abstract:
  We prove a sharp integral inequality for the dyadic maximal operator due to
which the evaluation of the Bellman function of this operator with respect to
two variables is possible, as can be seen in [3]. Our inequality of interest is
proved in this article by a simpler and more immediate way. We also study a
stability result in connection with this inequality, that is we provide a
necessary and sufficient condition, for a sequence of functions,under which we
obtain equality in the limit. The proof of this result is based on the proof of
the related inequality which we present in this article.


title:
Observing---and Imaging---Active Galactic Nuclei with the Event Horizon
  Telescope

abstract:
  Originally developed to image the shadow region of the central black hole in
Sagittarius A* and in the nearby galaxy M87, the Event Horizon Telescope (EHT)
provides deep, very high angular resolution data on other AGN sources too. The
challenges of working with EHT data have spurred the development of new image
reconstruction algorithms. This work briefly reviews the status of the EHT and
its utility for observing AGN sources, with emphasis on novel imaging
techniques that offer the promise of better reconstructions at 1.3 mm and other
wavelengths.


title:
On the strong law of large numbers for $\varphi$-subgaussian random
  variables

abstract:
  For $p\ge 1$ let $\varphi_p(x)=x^2/2$ if $|x|\le 1$ and
$\varphi_p(x)=1/p|x|^p-1/p+1/2$ if $|x|>1$. For a random variable $\xi$ let
$\tau_{\varphi_p}(\xi)$ denote $\inf\{a\ge 0:\;\forall_{\lambda\in\mathbb{R}}\;
\ln\mathbb{E}\exp(\lambda\xi)\le\varphi_p(a\lambda)\}$; $\tau_{\varphi_p}$ is a
norm in a space $Sub_{\varphi_p}=\{\xi:\;\tau_{\varphi_p}(\xi)<\infty\}$ of
$\varphi_p$-subgaussian random variables. We prove that if for a sequence
$(\xi_n)\subset Sub_{\varphi_p}$ ($p>1$) there exist positive constants $c$ and
$\alpha$ such that for every natural number $n$ the following inequality
$\tau_{\varphi_p}(\sum_{i=1}^n\xi_i)\le cn^{1-\alpha}$ holds then
$n^{-1}\sum_{i=1}^n\xi_i$ converges almost surely to zero as $n\to\infty$. This
result is a generalization of the SLLN for independent subgaussian random
variables (Taylor and Hu \cite{TayHu}) to the case of dependent
$\varphi_p$-subgaussian random variables.


title: Multivariate CLT follows from strong Rayleigh property

abstract:
  Let $(X_1 , \ldots , X_d)$ be random variables taking nonnegative integer
values and let $f(z_1, \ldots , z_d)$ be the probability generating function.
Suppose that $f$ is real stable; equivalently, suppose that the polarization of
this probability distribution is strong Rayleigh. In specific examples, such as
occupation counts of disjoint sets by a determinantal point process, it is
known~\cite{soshnikov02} that the joint distribution must approach a
multivariate Gaussian distribution. We show that this conclusion follows
already from stability of $f$.