title: Identities between Modular Graph Forms

abstract:
  This paper investigates the relations between modular graph forms, which are
generalizations of the modular graph functions that were introduced in earlier
papers motivated by the structure of the low energy expansion of genus-one Type
II superstring amplitudes. These modular graph forms are multiple sums
associated with decorated Feynman graphs on the world-sheet torus. The action
of standard differential operators on these modular graph forms admits an
algebraic representation on the decorations. First order differential operators
are used to map general non-holomorphic modular graph functions to holomorphic
modular forms. This map is used to provide proofs of the identities between
modular graph functions for weight less than six conjectured in earlier work,
by mapping these identities to relations between holomorphic modular forms
which are proven by holomorphic methods. The map is further used to exhibit the
structure of identities at arbitrary weight.


title:
How vortex bound states affect the Hall conductivity of a chiral $p\pm i
  p$ superconductor

abstract:
  The physics of a planar chiral $p\pm i p$ superconductor is studied for
various vortex configurations. The occurrence of vortex quasi-particle bound
states is exposed together with their ensuing collective properties, such as
sub-gap bands induced by inter-vortex tunneling. A general method to
diagonalize the Hamiltonian of a superconductor in the presence of a vortex
lattice is developed, that employs only smooth gauge transformations. It
renders the Hamiltonian to be periodic (thus allowing the use of a Bloch
theorem) and enables the treatment of systems with vortices of finite radii.
The pertinent anomalous charge response $c_{xy}$ is calculated (using the
Streda formula), and reveals that it contains a quantized contribution. This is
attributed to the response to the nucleation of vortices, from which we deduce
the system's quantum phase.

categories: cond-mat.supr-con cond-mat.stat-mech math-ph math.MP


title: Automatic segmentation of lizard spots using an active contour model

abstract:
  Animal biometrics is a challenging task. In the literature, many algorithms
have been used, e.g. penguin chest recognition, elephant ears recognition and
leopard stripes pattern recognition, but to use technology to a large extent in
this area of research, still a lot of work has to be done. One important target
in animal biometrics is to automate the segmentation process, so in this paper
we propose a segmentation algorithm for extracting the spots of Diploglossus
millepunctatus, an endangered lizard species. The automatic segmentation is
achieved with a combination of preprocessing, active contours and morphology.
The parameters of each stage of the segmentation algorithm are found using an
optimization procedure, which is guided by the ground truth. The results show
that automatic segmentation of spots is possible. A 78.37 % of correct
segmentation in average is reached.


title: On controlling networks of limit-cycle oscillators

abstract:
  The control of network-coupled nonlinear dynamical systems is an active area
of research in the nonlinear science community. Coupled oscillator networks
represent a particularly important family of nonlinear systems, with
applications ranging from the power grid to cardiac excitation. Here we study
the control of network-coupled limit cycle oscillators, extending previous work
that focused on phase oscillators. Based on stabilizing a target fixed point,
our method aims to attain complete frequency synchronization, i.e., consensus,
by applying control to as few oscillators as possible. We develop two types of
control. The first type directs oscillators towards to larger amplitudes, while
the second does not. We present numerical examples of both control types and
comment on the potential failures of the method.


title:
Effects of magnetic field and twin domains on magnetostructural phase
  mixture in Mn3O4: Raman scattering studies of untwinned crystals

abstract:
  The ferrimagnetic spinel Mn3O4 exhibits large and anisotropic changes in
electronic and structural properties in response to an applied magnetic field.
These changes are thought to result from the field-dependent tuning---via
strong spin-lattice coupling---between two nearly degenerate magnetostructural
phases. Recent variable-magnetic-field studies of Mn3O4 have been performed on
melt-grown crystals, which can exhibit twin domains due to a Jahn-Teller
structural transition below the melting temperature. Because of the near
degeneracy of the magnetostructural phases, however, strain associated with the
twin domains likely affects the magnetic responses of Mn3O4. In this report, we
present a variable-magnetic-field Raman scattering study of untwinned Mn3O4
crystals grown out of a flux below the Jahn-Teller structural transition. We
measure distinct q = 0 magnetic and vibrational excitation spectra for each
isolated magnetostructural phase of untwinned Mn3O4 crystals and determine the
symmetries of the observed excitations. We determine how the magnetostructural
phase mixture changes in response to magnetic fields applied in the magnetic
easy plane. Lastly, by comparing results on flux- and melt-grown Mn3O4
crystals, we show that the intrinsic mixture of the two magnetostructural
phases is indeed strongly influenced by the presence of twin domains.


title: Size quantization of Dirac fermions in graphene constrictions

abstract:
  Quantum point contacts (QPCs) are cornerstones of mesoscopic physics and
central building blocks for quantum electronics. Although the Fermi wave-length
in high-quality bulk graphene can be tuned up to hundreds of nanometers, the
observation of quantum confinement of Dirac electrons in nanostructured
graphene systems has proven surprisingly challenging. Here we show ballistic
transport and quantized conductance of size-confined Dirac fermions in
lithographically-defined graphene constrictions. At high charge carrier
densities, the observed conductance agrees excellently with the Landauer theory
of ballistic transport without any adjustable parameter. Experimental data and
simulations for the evolution of the conductance with magnetic field
unambiguously confirm the identification of size quantization in the
constriction. Close to the charge neutrality point, bias voltage spectroscopy
reveals a renormalized Fermi velocity ($v_F \approx 1.5 \times 10^6 m/s$) in
our graphene constrictions. Moreover, at low carrier density transport
measurements allow probing the density of localized states at edges, thus
offering a unique handle on edge physics in graphene devices.


title: Shallow and Deep Convolutional Networks for Saliency Prediction

abstract:
  The prediction of salient areas in images has been traditionally addressed
with hand-crafted features based on neuroscience principles. This paper,
however, addresses the problem with a completely data-driven approach by
training a convolutional neural network (convnet). The learning process is
formulated as a minimization of a loss function that measures the Euclidean
distance of the predicted saliency map with the provided ground truth. The
recent publication of large datasets of saliency prediction has provided enough
data to train end-to-end architectures that are both fast and accurate. Two
designs are proposed: a shallow convnet trained from scratch, and a another
deeper solution whose first three layers are adapted from another network
trained for classification. To the authors knowledge, these are the first
end-to-end CNNs trained and tested for the purpose of saliency prediction.


title: Mapping class group orbits of curves with self-intersections

abstract:
  We study mapping class group orbits of homotopy and isotopy classes of curves
with self-intersections. We exhibit the asymptotics of the number of such
orbits of curves with a bounded number of self-intersections, as the complexity
of the surface tends to infinity. We also consider the minimal genus of a
subsurface that contains the curve. We determine the asymptotic number of
orbits of curves with a fixed minimal genus and a bounded self-intersection
number, as the complexity of the surface tends to infinity. As a corollary of
our methods, we obtain that most curves that are homotopic are also isotopic.
Furthermore, using a theorem by Basmajian, we get a bound on the number of
mapping class group orbits on a given a hyperbolic surface that can contain
short curves. For a fixed length, this bound is polynomial in the signature of
the surface. The arguments we use are based on counting embeddings of ribbon
graphs.


title:
Shortest Paths and Convex Hulls in 2D Complexes with Non-Positive
  Curvature

abstract:
  Globally non-positively curved, or CAT(0), polyhedral complexes arise in a
number of applications, including evolutionary biology and robotics. These
spaces have unique shortest paths and are composed of Euclidean polyhedra, yet
many algorithms and properties of shortest paths and convex hulls in Euclidean
space fail to transfer over. We give an algorithm, using linear programming, to
compute the convex hull of a set of points in a 2-dimensional CAT(0) polyhedral
complex with a single vertex. We explore the use of shortest path maps to
answer single-source shortest path queries in 2-dimensional CAT(0) polyhedral
complexes, and we unify efficient solutions for 2-manifold and rectangular
cases.


title:
Numerical solution of an ill-posed Cauchy problem for a quasilinear
  parabolic equation using a Carleman weight function

abstract:
  This is the first publication in which an ill-posed Cauchy problem for a
quasi- linear PDE is solved numerically by a rigorous method. More precisely,
we solve the side Cauchy problem for a 1-d quasilinear parabolc equation. The
key idea is to minimize a strictly convex cost functional with the Carleman
Weight Function in it. Previous publications about numerical solutions of
ill-posed Cauchy problems were considering only linear equations.


title: On maximal analytical extension of the Vaidya metric

abstract:
  The classical Vaidya metric is transformed to the special diagonal
coordinates in the case of the linear mass function allowing rather easy
treatment. We find the exact analytical expressions for metric functions in
these diagonal coordinates. Using these coordinates, we elaborate the maximum
analytic extension of the Vaidya metric with a linear growth of the black hole
mass and construct the corresponding Carter-Penrose diagrams for different
specific cases. The derived global geometry seemingly is valid also for a more
general behavior of the black hole mass in the Vaidya metric.


title:
Tipping elements and climate-economic shocks: Pathways toward integrated
  assessment

abstract:
  The literature on the costs of climate change often draws a link between
climatic 'tipping points' and large economic shocks, frequently called
'catastrophes'. The use of the phrase 'tipping points' in this context can be
misleading. In popular and social scientific discourse, 'tipping points'
involve abrupt state changes. For some climatic 'tipping points,' the
commitment to a state change may occur abruptly, but the change itself may be
rate-limited and take centuries or longer to realize. Additionally, the
connection between climatic 'tipping points' and economic losses is tenuous,
though emerging empirical and process-model-based tools provide pathways for
investigating it. We propose terminology to clarify the distinction between
'tipping points' in the popular sense, the critical thresholds exhibited by
climatic and social 'tipping elements,' and 'economic shocks'. The last may be
associated with tipping elements, gradual climate change, or non-climatic
triggers. We illustrate our proposed distinctions by surveying the literature
on climatic tipping elements, climatically sensitive social tipping elements,
and climate-economic shocks, and we propose a research agenda to advance the
integrated assessment of all three.


title: Superconformal index of N=3 orientifold theories

abstract:
  We analyze the superconformal index of the N=3 supersymmetric Z_k generalized
orientifold theories recently proposed. In the large N limit we derive the
index from the Kaluza-Klein modes in AdS_5 x S^5/Z_k, which are obtained from
ones in AdS_5 x S^5 by a simple projection. For the ordinary Z_2 orientifold
case the agreement with the gauge theory calculation is explicitly confirmed,
and for Z_k with k > 2 we perform a few consistency checks with known results
for N=3 theories. We also study finite N corrections by analyzing wrapped
D3-branes and discrete torsions in the dual geometry.


title: Mass gap in the critical gravitational collapse of a kink

abstract:
  We study the gravitational collapse of a kink within spherical symmetry and
the characteristic formulation of General Relativity. We explore some expected
but elusive gravitational collapse issues which have not been studied before in
detail, finding new features. The numerical one-parametric solution and the
structure of the spacetime are calculated using finite differences, Galerkin
collocation techniques, and some scripting for automated grid coverage. We
study the threshold of black hole formation and confirm a mass gap in the phase
transition. In the supercritical case we find a mass scaling power law
$M_{BH}={M^*_{BH}}+K[\lambda-\lambda^*]^{2\gamma}+f(K[\lambda-\lambda^*]^{2\gamma})$,
with $\gamma\approx 0.37$ independent of the initial data for the cases
considered, and $M^*_{BH}$, $K$ and $\lambda^*$ each depending on the initial
datum. The spacetime has a self-similar structure with a period of
$\Delta\approx 3.4$. In the subcritical case the Bondi mass at null infinity
decays in cascade with $\Delta/2$ interval as expected.


title: Electromagnetic Field in Lyra Manifold: A First Order Approach

abstract:
  We discuss the coupling of the electromagnetic field with a curved and
torsioned Lyra manifold using the Duffin-Kemmer-Petiau theory. We will show how
to obtain the equations of motion and energy-momentum and spin density tensors
by means of the Schwinger Variational Principle.

categories: gr-qc astro-ph.CO hep-th math-ph math.DG math.MP


title: Continuous products of matrices

abstract:
  We answer the question if the continuous product of square matrices $M(t)$
over $t\in [0,1]$ can be correctly defined. The case where all $M(t)$ are taken
from a finite set $\Sigma$ is studied. We find necessary and sufficient
conditions on $\Sigma$ that ensure the convergence of products
$M(t_{0}=0)M(t_{1})\dots M(t_{N}=1)$ as the partition $0<t_{1}<\dots<1$
refines. These conditions are properties LCP (left convergent product) and RCP
(right convergent product) of the set $\Sigma$. That is, it suffices to require
the convergence of all finite products $M_{1}M_{2}\dots M_{K}$ and $M_{K}\dots
M_{2}M_{1}$ as $K\to\infty$, where $M_{i}\in\Sigma$. The theory of joint
spectral radius is heavily used.


title: On the geometric mean of the first n primes

abstract:
  Let $p_n$ be the $n$th prime, and consider the sequence $s_n = (2\cdot3\cdots
p_n)^{1/n} = (p_n\#)^{1/n}$, the geometric mean of the first $n$ primes. We
give a short proof that $p_n/s_n \to e$, a result conjectured by Vrba (2010)
and proved by Sandor and Verroken (2011). We show that $p_n/s_n = \exp(1+1/\log
p_n + O(1/\log^2 p_n))$ as $n\to\infty$, and give explicit lower and upper
bounds for the $O(1/\log^2 p_n)$ term.


title: Molecular Graph Convolutions: Moving Beyond Fingerprints

abstract:
  Molecular "fingerprints" encoding structural information are the workhorse of
cheminformatics and machine learning in drug discovery applications. However,
fingerprint representations necessarily emphasize particular aspects of the
molecular structure while ignoring others, rather than allowing the model to
make data-driven decisions. We describe molecular "graph convolutions", a
machine learning architecture for learning from undirected graphs, specifically
small molecules. Graph convolutions use a simple encoding of the molecular
graph---atoms, bonds, distances, etc.---which allows the model to take greater
advantage of information in the graph structure. Although graph convolutions do
not outperform all fingerprint-based methods, they (along with other
graph-based methods) represent a new paradigm in ligand-based virtual screening
with exciting opportunities for future improvement.


title:
Bounds on the Quenched Pressure and Main Eigenvalue of the Ruelle
  Operator for Brownian Type Potentials

abstract:
  In this paper we consider a random potential derived from the Brownian
motion. We obtain upper and lower bounds for the expected value of the main
eigenvalue of the associated Ruelle operator and for its quenched topological
pressure. We also exhibit an isomorphism between the space $C(\Omega)$ endowed
with its standard norm and a proper closed subspace of the Skorokhod space
which is used to obtain a stochastic functional equation for the main
eigenvalue and for its associated eigenfunction.


title:
Pareto optimal matchings of students to courses in the presence of
  prerequisites

abstract:
  We consider the problem of allocating applicants to courses, where each
applicant has a subset of acceptable courses that she ranks in strict order of
preference. Each applicant and course has a capacity, indicating the maximum
number of courses and applicants they can be assigned to, respectively. We thus
essentially have a many-to-many bipartite matching problem with one-sided
preferences, which has applications to the assignment of students to optional
courses at a university. We consider additive preferences and lexicographic
preferences as two means of extending preferences over individual courses to
preferences over bundles of courses. We additionally focus on the cases that
courses have prerequisite constraints and where courses may be corequisites.
  For these extensions to the basic problem, we present the following
algorithmic results, which are mainly concerned with the computation of Pareto
optimal matchings (POMs). Firstly, we consider compulsory prerequisites. For
additive preferences, we show that the problem of finding a POM is NP-hard. On
the other hand, in the case of lexicographic preferences we give a
polynomial-time algorithm for finding a POM, based on the well-known sequential
mechanism. However we show that the problem of deciding whether a given
matching is Pareto optimal is co-NP-complete. We further prove that finding a
maximum cardinality (Pareto optimal) matching is NP-hard. Under alternative
prerequisites, we show that finding a POM is NP-hard for either additive or
lexicographic preferences. Finally we consider corequisites. We prove that, as
in the case of compulsory prerequisites, finding a POM is NP-hard for additive
preferences, though solvable in polynomial time for lexicographic preferences.
In the latter case, the problem of finding a maximum cardinality POM is NP-hard
and very difficult to approximate


title: QoE-Based Low-Delay Live Streaming Using Throughput Predictions

abstract:
  Recently, HTTP-based adaptive streaming has become the de facto standard for
video streaming over the Internet. It allows clients to dynamically adapt media
characteristics to network conditions in order to ensure a high quality of
experience, that is, minimize playback interruptions, while maximizing video
quality at a reasonable level of quality changes. In the case of live
streaming, this task becomes particularly challenging due to the latency
constraints. The challenge further increases if a client uses a wireless
network, where the throughput is subject to considerable fluctuations.
Consequently, live streams often exhibit latencies of up to 30 seconds. In the
present work, we introduce an adaptation algorithm for HTTP-based live
streaming called LOLYPOP (Low-Latency Prediction-Based Adaptation) that is
designed to operate with a transport latency of few seconds. To reach this
goal, LOLYPOP leverages TCP throughput predictions on multiple time scales,
from 1 to 10 seconds, along with an estimate of the prediction error
distribution. In addition to satisfying the latency constraint, the algorithm
heuristically maximizes the quality of experience by maximizing the average
video quality as a function of the number of skipped segments and quality
transitions. In order to select an efficient prediction method, we studied the
performance of several time series prediction methods in IEEE 802.11 wireless
access networks. We evaluated LOLYPOP under a large set of experimental
conditions limiting the transport latency to 3 seconds, against a
state-of-the-art adaptation algorithm from the literature, called FESTIVE. We
observed that the average video quality is by up to a factor of 3 higher than
with FESTIVE. We also observed that LOLYPOP is able to reach a broader region
in the quality of experience space, and thus it is better adjustable to the
user profile or service provider requirements.


title: Good reduction and canonical heights of subvarieties

abstract:
  We bound the length of the periodic part of the orbit of a preperiodic
rational subvariety via good reduction information. This bound depends only on
the degree of the map, the degree of the subvariety, the dimension of the
projective space, the degree of the number field, and the prime of good
reduction. As part of the proof, we extend the corresponding good reduction
bound for points proven by the author for non-singular varieties to all
projective varieties. Toward proving an absolute bound on the period for a
given map, we study the canonical height of a subvariety via Chow forms and
compute the bound between the height and canonical height of a subvariety. This
gives the existence of a bound on the number of preperiodic rational
subvarieties of bounded degree for a given map. An explicit bound is given for
hypersurfaces.


title: Truncated Random Measures

abstract:
  Completely random measures (CRMs) and their normalizations are a rich source
of Bayesian nonparametric priors. Examples include the beta, gamma, and
Dirichlet processes. In this paper we detail two major classes of sequential
CRM representations---series representations and superposition
representations---within which we organize both novel and existing sequential
representations that can be used for simulation and posterior inference. These
two classes and their constituent representations subsume existing ones that
have previously been developed in an ad hoc manner for specific processes.
Since a complete infinite-dimensional CRM cannot be used explicitly for
computation, sequential representations are often truncated for tractability.
We provide truncation error analyses for each type of sequential
representation, as well as their normalized versions, thereby generalizing and
improving upon existing truncation error bounds in the literature. We analyze
the computational complexity of the sequential representations, which in
conjunction with our error bounds allows us to directly compare representations
and discuss their relative efficiency. We include numerous applications of our
theoretical results to commonly-used (normalized) CRMs, demonstrating that our
results enable a straightforward representation and analysis of CRMs that has
not previously been available in a Bayesian nonparametric context.


title: Order nine MMIK graphs

abstract:
  We show that there are exactly eight MMIK (minor minimal intrinsically
knotted) graphs of order nine.


title: Optimization via Chebyshev Polynomials

abstract:
  This paper presents for the first time a robust exact line-search method
based on a full pseudospectral (PS) numerical scheme employing orthogonal
polynomials. The proposed method takes on an adaptive search procedure and
combines the superior accuracy of Chebyshev PS approximations with the
high-order approximations obtained through Chebyshev PS differentiation
matrices (CPSDMs). In addition, the method exhibits quadratic convergence rate
by enforcing an adaptive Newton search iterative scheme. A rigorous error
analysis of the proposed method is presented along with a detailed set of
pseudocodes for the established computational algorithms. Several numerical
experiments are conducted on one- and multi-dimensional optimization test
problems to illustrate the advantages of the proposed strategy.


title: Prefactor in the dynamically assisted Sauter-Schwinger effect

abstract:
  The probability of creating an electron-positron pair out of the quantum
vacuum by a strong electric field can be enhanced tremendously via an
additional weaker time-dependent field. This dynamically assisted
Sauter-Schwinger effect has already been studied in several works. It has been
found that the enhancement mechanism depends on the shape of the weaker field.
For example, a Sauter pulse $1/\cosh(\omega t)^2$ and a Gaussian profile
$\exp(-\omega^2 t^2)$ exhibit significant, qualitative differences. However, so
far most of the analytical studies were focused on the exponent entering the
pair-creation probability. Here, we study the subleading prefactor in front of
the exponential using the worldline instanton method. We find that the main
features of the dynamically assisted Sauter-Schwinger effect, including the
dependence on the shape of the weaker field, are basically unaffected by the
prefactor. To test the validity of the instanton approximation, we compare the
number of produced pairs to a numerical integration of the full Riccati
equation.


title: On the anomalies in the latest LHCb data

abstract:
  Depending on the assumptions on the power corrections to the exclusive b -> s
l+ l- decays, the latest data of the LHCb collaboration - based on the 3 fb^-1
data set and on two different experimental analysis methods - still shows some
tensions with the SM predictions. We present a detailed analysis of the
theoretical inputs and various global fits to all the available b -> s l+ l-
data. This constitutes the first global analysis of the new data of the LHCb
collaboration based on the hypothesis that these tensions can be at least
partially explained by new physics contributions. In our model-independent
analysis we present one-, two-, four-, and also five-dimensional global fits in
the space of Wilson coefficients to all available b -> s l+ l- data. We also
compare the two different experimental LHCb analyses of the angular observables
in B -> K* mu+ mu-. We explicitly analyse the dependence of our results on the
assumptions about power corrections, but also on the errors present in the form
factor calculations. Moreover, based on our new global fits we present
predictions for ratios of observables which may show a sign of lepton
non-universality. Their measurements would crosscheck the LHCb result on the
ratio R_K = BR(B+ -> K+ mu+ mu-) / BR(B+ -> K+ e+ e-) in the low-q^2 region
which deviates from the SM prediction by 2.6 sigma.


title: Optical and Transport Properties in 3D Dirac and Weyl Semimetals

abstract:
  Within a Kubo formalism, we study dc transport and ac optical properties of
3D Dirac and Weyl semimetals. Emphasis is placed on the approach to charge
neutrality and on the differences between Dirac and Weyl materials. At charge
neutrality, the zero-temperature limit of the dc conductivity is not universal
and also depends on the residual scattering model employed. However, the Lorenz
number L retains its usual value L_0. With increasing temperature, the
Wiedemann-Franz law is violated. At high temperatures, L exhibits a new plateau
at a value dependent on the details of the scattering rate. Such details can
also appear in the optical conductivity, both in the Drude response and
interband background. In the clean limit, the interband background is linear in
photon energy and always extrapolates to the origin. This background can be
shifted to the right through the introduction of a massless gap. In this case,
the extrapolation can cut the axis at a finite photon energy as is observed in
some experiments. It is also of interest to differentiate between the two types
of Weyl semimetals: those with broken time-reversal symmetry and those with
broken spatial-inversion symmetry. We show that, while the former will follow
the same behaviour as the 3D Dirac semimetals, for the zero magnetic field
properties discussed here, the latter type will show a double step in the
optical conductivity at finite doping and a single absorption edge at charge
neutrality. The Drude conductivity is always finite in this case, even at
charge neutrality.


title:
Investigating magnetic activity in very stable stellar magnetic fields:
  long-term photometric and spectroscopic study of the fully convective M4
  dwarf V374 Peg

abstract:
  The ultrafast-rotating ($P_\mathrm{rot}\approx0.44 d$) fully convective
single M4 dwarf V374 Peg is a well-known laboratory for studying intense
stellar activity in a stable magnetic topology. As an observable proxy for the
stellar magnetic field, we study the stability of the light curve, and thus the
spot configuration. We also measure the occurrence rate of flares and coronal
mass ejections (CMEs). We analyse spectroscopic observations, $BV(RI)_C$
photometry covering 5 years, and additional $R_C$ photometry that expands the
temporal base over 16 years. The light curve suggests an almost rigid-body
rotation, and a spot configuration that is stable over about 16 years,
confirming the previous indications of a very stable magnetic field. We
observed small changes on a nightly timescale, and frequent flaring, including
a possible sympathetic flare. The strongest flares seem to be more concentrated
around the phase where the light curve indicates a smaller active region.
Spectral data suggest a complex CME with falling-back and re-ejected material,
with a maximal projected velocity of $\approx$675km/s. We observed a CME rate
much lower than expected from extrapolations of the solar flare-CME relation to
active stars.


title: Amplitude analysis of $\bar{K}N$ scattering

abstract:
  We present the results of a coupled-channel model for $\bar{K}N$ scattering
in the resonance region. The model fulfills unitarity, has the correct
analytical properties for the amplitudes and the partial waves have the right
threshold behavior. The parameters of the model have been established by
fitting single-energy partial waves up to $J=7/2$ and up to 2.15 GeV of
center-of-mass energy. The $\Lambda^*$ and $\Sigma^*$ spectra has been
obtained, providing a comprehensive picture of the $S=-1$ hyperon spectrum. We
use the structure of the hyperon spectrum and Regge phenomenology to gain
insight on the nature of the $\Lambda(1405)$ resonances.


title:
Proto-Cooperation: group hunting sailfish improve hunting success by
  alternating attacks on grouping prey

abstract:
  We present evidence of a novel form of group hunting. Individual sailfish
(Istiophorus platypterus) alternate attacks with other group members on their
schooling prey (Sardinella aurita). While only 24% of attacks result in prey
capture, multiple prey are injured in 95% of attacks, resulting in an increase
of injured fish in the school with the number of attacks. How quickly prey are
captured is positively correlated with the level of injury of the school,
suggesting that hunters can benefit from other conspecifics' attacks on the
prey. To explore this, we built a mathematical model capturing the dynamics of
the hunt. We show that group hunting provides major efficiency gains (prey
caught per unit time) for individuals in groups of up to 70 members. We also
demonstrate that a free riding strategy, where some individuals wait until the
prey are sufficiently injured before attacking, is only beneficial if the cost
of attacking is high, and only then when waiting times are short. Our findings
provide evidence that cooperative benefits can be realised through the
facilitative effects of individuals' hunting actions without spatial
coordination of attacks. Such "proto-cooperation" may be the pre-cursor to more
complex group-hunting strategies.


title: Magnetars and White Dwarf Pulsars

abstract:
  The Anomalous X-ray Pulsars (AXPs) and Soft Gamma-ray Repeaters (SGRs) are a
class of pulsars understood as neutron stars (NSs) with super strong surface
magnetic fields, namely $B\gtrsim10^{14}$ G, and for that reason are known as
Magnetars. However, in the last years some SGRs/AXPs with low surface magnetic
fields $B\sim(10^{12}-10^{13})$ G have been detected, challenging the Magnetar
description. Moreover, some fast and very magnetic white dwarfs (WDs) have also
been observed, and at least one showed X-Ray energy emission as an ordinary
pulsar. Following this fact, an alternative model based on white dwarfs pulsars
has been proposed to explain this special class of pulsars. In this model, AXPs
and SGRs as dense and magnetized white dwarfs can have surface magnetic field
$B\sim 10^{7}-10^{10}$ G and rotate very fast with frequencies $\Omega\sim 1$
rad/s, consistent with the observed rotation periods $P\sim (2-12)$ s.


title:
Electromagnetic waves, gravitational waves and the prophets who
  predicted them

abstract:
  Using non-excessively-technical language and written in informal style, this
article introduces the reader to the concepts of electromagnetic and
gravitational waves and recounts the prediction of existence of these waves by
Maxwell and Einstein, respectively. The issue of gravitational radiation is
timely in view of the recent announcement of the detection of gravitational
waves by the LIGO scientific team.


title: Principal Component Analysis of Quantum Correlation

abstract:
  The concept of quantum correlation matrix for observables leads to the
application of the PCA (Principal Component Analysis) also for quantum system
in Hilbert space. It is shown that, in the case of a 2x2 spin system where the
observables are the Pauli matrices and a polarization vector is acting on the
density matrix, meaningful results can be obtained by the PCA in terms of qubit
properties. In particular, it is shown that by choosing, for example, the (x,z)
spinors, the axes of the principal components (PC) coincide with the circular
polarization basis on the Block Sphere.


title: On the structure of tidally-disrupted stellar debris streams

abstract:
  A tidal disruption event (TDE) -- when a star is destroyed by the immense
gravitational field of a supermassive black hole -- transforms a star into a
stream of tidally-shredded debris. The properties of this debris ultimately
determine the observable signatures of TDEs. Here we derive a simple,
self-similar solution for the velocity profile of the debris streams produced
from TDEs, and show that this solution agrees extremely well with numerical
results. Using this self-similar solution, we calculate an analytic,
approximate expression for the radial density profile of the stream. We show
that there is a critical adiabatic index that varies as a function of position
along the stream above (below) which the stream is unstable (stable) to
gravitational fragmentation. We also calculate the impact of heating and
cooling on this stability criterion.


title:
Star formation along the Hubble sequence: Radial structure of the star
  formation of CALIFA galaxies

abstract:
  The aim of this paper is to characterize the radial structure of the star
formation rate (SFR) in galaxies in the nearby Universe as represented by the
CALIFA survey. The sample under study contains 416 galaxies observed with IFS,
covering a wide range of Hubble types and stellar masses. Spectral synthesis
techniques are applied to obtain radial profiles of the intensity of the star
formation rate in the recent past, and the local sSFR. To emphasize the
behavior of these properties for galaxies that are on and off the main sequence
of star formation (MSSF) we stack the individual radial profiles in bins of
galaxy morphology and stellar masses. Our main results are: a) The intensity of
SFR shows declining profiles that exhibit very little differences between
spirals. The dispersion between the profiles is significantly smaller in late
type spirals. This confirms that the MSSF is a sequence of galaxies with nearly
constant intensity of SFR b) sSFR values scale with Hubble type and increase
radially outwards, with a steeper slope in the inner 1 HLR. This behavior
suggests that galaxies are quenched inside-out, and that this process is faster
in the central, bulge-dominated part than in the disks. c) As a whole, and at
all radii, E and S0 are off the MSSF. d) Applying the volume-corrections for
the CALIFA sample, we obtain a density of star formation in the local Universe
of 0.0105 Msun/yr/Mpc^{-3}. Most of the star formation is occurring in the
disks of spirals. e) The volume averaged birthrate parameter, b'=0.39, suggests
that the present day Universe is forming stars at 1/3 of its past average rate.
E, S0, and the bulge of early type spirals contribute little to the recent SFR
of the Universe, which is dominated by the disks of later spirals. f) There is
a tight relation between the intensity of the SFR and stellar mass, defining a
local MSSF relation with a logarithmic slope of 0.8.


title:
The Contraction/Expansion History of Charon with implication for its
  Planetary Scale Tectonic Belt

abstract:
  The New Horizons mission to the Kuiper Belt has recently revealed intriguing
features on the surface of Charon, including a network of chasmata, cutting
across or around a series of high topography features, conjoining to form a
belt. It is proposed that this tectonic belt is a consequence of
contraction/expansion episodes in the moon's evolution associated particularly
with compaction, differentiation and geochemical reactions of the interior. The
proposed scenario involves no need for solidification of a vast subsurface
ocean and/or a warm initial state. This scenario is based on a new, detailed
thermo-physical evolution model of Charon that includes multiple processes.
According to the model, Charon experiences two contraction/expansion episodes
in its history that may provide the proper environment for the formation of the
tectonic belt. This outcome remains qualitatively the same, for several
different initial conditions and parameter variations. The precise orientation
of Charon's tectonic belt, and the cryovolcanic features observed south of the
tectonic belt may have involved a planetary-scale impact, that occurred only
after the belt had already formed.


title:
The Carnegie-Irvine Galaxy Survey. IV. A Method to Determine the Average
  Mass Ratio of Mergers That Built Massive Elliptical Galaxies

abstract:
  Many recent observations and numerical simulations suggest that nearby
massive, early-type galaxies were formed through a "two-phase" process. In the
proposed second phase, the extended stellar envelope was accumulated through
many dry mergers. However, details of the past merger history of present-day
ellipticals, such as the typical merger mass ratio, are difficult to constrain
observationally. Within the context and assumptions of the two-phase formation
scenario, we propose a straightforward method, using photometric data alone, to
estimate the average mass ratio of mergers that contributed to the build-up of
massive elliptical galaxies. We study a sample of nearby massive elliptical
galaxies selected from the Carnegie-Irvine Galaxy Survey, using two-dimensional
analysis to decompose their light distribution into an inner, denser component
plus an extended, outer envelope, each having a different optical color. The
combination of these two substructures accurately recovers the negative color
gradient exhibited by the galaxy as whole. The color difference between the two
components (<\Delta(B-V)> ~ 0.10 mag; <\Delta(B-R)> ~ 0.14 mag), based on the
slope of the M_stellar-color relation for nearby early-type galaxies, can be
translated into an estimate of the average mass ratio of the mergers. The rough
estimate, 1:5 to 1:10, is consistent with the expectation of the two-phase
formation scenario, suggesting that minor mergers were largely responsible for
building up to the outer stellar envelope of present-day massive ellipticals.
With the help of accurate photometry, large sample size, and more choices of
colors promised by ongoing and future surveys, the approach proposed here can
reveal more insights into the growth of massive galaxies during the last few
Gyr.


title:
EVN Observations of HESS J1943+213: Evidence for an Extreme TeV BL Lac
  Object

abstract:
  We report on the 1.6 GHz (18 cm) VLBI observations of the unresolved, steady
TeV source HESS J1943+213 located in the Galactic plane, performed with the
European VLBI Network (EVN) in 2014. Our new observations with a nearly full
EVN array provide the deepest image of HESS J1943+213 at the highest resolution
ever achieved, enabling us to resolve the long-standing issues of the source
identification. The milliarcsecond-scale structure of HESS J1943+213 has a
clear asymmetric morphology, consisting of a compact core and a diffuse
jet-like tail. This is broadly consistent with the previous e-EVN observations
of the source performed in 2011, and re-analyzed in this work. The core
component is characterized by the brightness temperature of $\gtrsim1.8 \times
10^9$ K, which is typical for low-luminosity blazars in general. Overall, radio
properties of HESS J1943+213 are consistent with the source classification as
an "extreme high-frequency-peaked BL Lac object". Remarkably, we note that
since HESS J1943+213 does not reveal any optical or infrared signatures of the
AGN activity, it would never be recognized and identified as a BL Lac object,
if not its location close to the Galactic plane where the High Energy
Stereoscopic System has surveyed, and the follow-up dedicated X-ray and radio
studies triggered by the source detection in the TeV range. Our results suggest
therefore a presence of an unrecognized, possibly very numerous population of
particularly extreme HBLs, and simultaneously demonstrate that the
low-frequency VLBI observations with high-angular resolution are indispensable
for a proper identification of such objects.


title: A novel look at energy equipartition in globular clusters

abstract:
  Two-body interactions play a major role in shaping the structural and
dynamical properties of globular clusters (GCs) over their long-term evolution.
In particular, GCs evolve toward a state of partial energy equipartition that
induces a mass-dependence in their kinematics. By using a set of Monte Carlo
cluster simulations evolved in quasi-isolation, we show that the stellar mass
dependence of the velocity dispersion $\sigma(m)$ can be described by an
exponential function $\sigma^2\propto \exp(-m/m_\mathrm{eq})$, with the
parameter $m_\mathrm{eq}$ quantifying the degree of partial energy
equipartition of the systems. This simple parametrization successfully captures
the behaviour of the velocity dispersion at lower as well as higher stellar
masses, that is, the regime where the system is expected to approach full
equipartition. We find a tight correlation between the degree of equipartition
reached by a GC and its dynamical state, indicating that clusters that are more
than about 20 core relaxation times old, have reached a maximum degree of
equipartition. This equipartition$-$dynamical state relation can be used as a
tool to characterize the relaxation condition of a cluster with a kinematic
measure of the $m_\mathrm{eq}$ parameter. Vice versa, the mass-dependence of
the kinematics can be predicted knowing the relaxation time solely on the basis
of photometric measurements. Moreover, any deviations from this tight relation
could be used as a probe of a peculiar dynamical history of a cluster. Finally,
our novel approach is important for the interpretation of state-of-the-art
Hubble Space Telescope proper motion data, for which the mass dependence of
kinematics can now be measured, and for the application of modeling techniques
which take into consideration multi-mass components and mass segregation.


title: Heavy neutrino impact on the triple Higgs coupling

abstract:
  We present the first calculation of the one-loop corrections to the triple
Higgs coupling in the framework of a simplified 3+1 Dirac neutrino model, that
is three light neutrinos plus one heavy neutrino embedded in the Standard Model
(SM). The triple Higgs coupling is a key parameter of the scalar potential
triggering the electroweak symmetry-breaking mechanism in the SM. The impact of
the heavy neutrino can be as large as $+20\%$ to $+30\%$ for parameter points
allowed by the current experimental constraints depending on the tightness of
the perturbative bound. This can be probed at the high-luminosity LHC, at
future electron-positron colliders and at the Future Circular Collider in
hadron-hadron mode, an envisioned 100 TeV $pp$ machine. Our calculation, being
done in the mass basis, can be extended to any model using the neutrino portal.
In addition, the effects that we have calculated are expected to be enhanced if
additional heavy fermions with large Yukawa couplings are included, as in
low-scale seesaw mechanisms.


title:
Many body localization and thermalization: insights from the
  entanglement spectrum

abstract:
  We study the entanglement spectrum in the many body localizing and
thermalizing phases of one and two dimensional Hamiltonian systems, and
periodically driven `Floquet' systems. We focus on the level statistics of the
entanglement spectrum as obtained through numerical diagonalization, finding
structure beyond that revealed by more limited measures such as entanglement
entropy. In the thermalizing phase the entanglement spectrum obeys level
statistics governed by an appropriate random matrix ensemble. For Hamiltonian
systems this can be viewed as evidence in favor of a strong version of the
eigenstate thermalization hypothesis (ETH). Similar results are also obtained
for Floquet systems, where they constitute a result `beyond ETH', and show that
the corrections to ETH governing the Floquet entanglement spectrum have
statistical properties governed by a random matrix ensemble. The particular
random matrix ensemble governing the Floquet entanglement spectrum depends on
the symmetries of the Floquet drive, and therefore can depend on the choice of
origin of time. In the many body localized phase the entanglement spectrum is
also found to show level repulsion, following a semi-Poisson distribution (in
contrast to the energy spectrum, which follows a Poisson distribution). This
semi-Poisson distribution is found to come mainly from states at high
entanglement energies. The observed level repulsion only occurs for interacting
localized phases. We also demonstrate that equivalent results can be obtained
by calculating with a single typical eigenstate, or by averaging over a
microcanonical energy window - a surprising result in the localized phase. This
discovery of new structure in the pattern of entanglement of localized and
thermalizing phases may open up new lines of attack on many body localization,
thermalization, and the localization transition.


title: The crowded magnetosphere of the post common envelope binary QS Virginis

abstract:
  We present high speed photometry and high resolution spectroscopy of the
eclipsing post common envelope binary QS Virginis (QS Vir). Our UVES spectra
span multiple orbits over more than a year and reveal the presence of several
large prominences passing in front of both the M star and its white dwarf
companion, allowing us to triangulate their positions. Despite showing small
variations on a timescale of days, they persist for more than a year and may
last decades. One large prominence extends almost three stellar radii from the
M star. Roche tomography reveals that the M star is heavily spotted and that
these spots are long-lived and in relatively fixed locations, preferentially
found on the hemisphere facing the white dwarf. We also determine precise
binary and physical parameters for the system. We find that the 14,220 +/- 350K
white dwarf is relatively massive, 0.782 +/- 0.013Ms, and has a radius of
0.01068 +/- 0.00007Rs, consistent with evolutionary models. The tidally
distorted M star has a mass of 0.382 +/- 0.006Ms and a radius of 0.381 +/-
0.003Rs, also consistent with evolutionary models. We find that the magnesium
absorption line from the white dwarf is broader than expected. This could be
due to rotation (implying a spin period of only ~700 seconds), or due to a weak
(~100kG) magnetic field, we favour the latter interpretation. Since the M
star's radius is still within its Roche lobe and there is no evidence that its
over-inflated we conclude that QS Vir is most likely a pre-cataclysmic binary
just about to become semi-detached.


title: Photometric Supernova Classification With Machine Learning

abstract:
  Automated photometric supernova classification has become an active area of
research in recent years in light of current and upcoming imaging surveys such
as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope, given
that spectroscopic confirmation of type for all supernovae discovered will be
impossible. Here, we develop a multi-faceted classification pipeline, combining
existing and new approaches. Our pipeline consists of two stages: extracting
descriptive features from the light curves and classification using a machine
learning algorithm. Our feature extraction methods vary from model-dependent
techniques, namely SALT2 fits, to more independent techniques fitting
parametric models to curves, to a completely model-independent wavelet
approach. We cover a range of representative machine learning algorithms,
including naive Bayes, k-nearest neighbors, support vector machines, artificial
neural networks and boosted decision trees (BDTs). We test the pipeline on
simulated multi-band DES light curves from the Supernova Photometric
Classification Challenge. Using the commonly used area under the curve (AUC) of
the Receiver Operating Characteristic as a metric, we find that the SALT2 fits
and the wavelet approach, with the BDTs algorithm, each achieves an AUC of
0.98, where 1 represents perfect classification. We find that a representative
training set is essential for good classification, whatever the feature set or
algorithm, with implications for spectroscopic follow-up. Importantly, we find
that by using either the SALT2 or the wavelet feature sets with a BDT
algorithm, accurate classification is possible purely from light curve data,
without the need for any redshift information.


title:
An OH(1720 MHz) Maser and a Nonthermal Radio Source in Sgr B2(M): A
  SNR--Molecular Cloud Interaction Site?

abstract:
  Sgr B2 is a well-known star forming molecular cloud complex in the Galactic
center region showing evidence of high energy activity as traced by the
K$\alpha$ neutral FeI line at 6.4 keV, as well as GeV and TeV $\gamma$-ray
emission. Here we present VLA and GMRT observations with respective resolutions
of $\approx3.5"\times1.2"$ and 25$"\times25"$ and report the detection of an
OH(1720 MHz) maser, with no accompanying OH 1665, 1667 and 1612 MHz maser
emission. The maser coincides with a 150 MHz nonthermal radio source in Sgr
B2(M). This rare class of OH(1720 MHz) masers or the so-called supernova
remnant (SNR) masers, with no main line transitions, trace shocked gas and
signal the interaction of an expanding SNR with a molecular cloud. We interpret
the 150 MHz radio source as either the site of a SNR -- molecular gas
interaction or a wind-wind collision in a massive binary system. The
interaction of the molecular cloud and the nonthermal source enhances the
cosmic-ray ionization rate, allows the diffusion of cosmic rays into the cloud
and produces the variable 6.4 keV line, GeV and TeV $\gamma$-ray emission from
Sgr B2(M). The cosmic ray electron interaction with the gas in the Galactic
center can not only explain the measured high values of cosmic ray ionization
and heating rates but also contribute to nonthermal bremsstrahlung continuum
emission, all of which are consistent with observations.


title:
Binary Black Holes in Dense Star Clusters: Exploring the Theoretical
  Uncertainties

abstract:
  Recent N-body simulations predict that large numbers of stellar black holes
(BHs) could remain bound to globular clusters (GCs) at present, and merging
BH--BH binaries are produced dynamically in significant numbers. We
systematically vary "standard" assumptions made by numerical simulations
related to, e.g., BH formation, stellar winds, binary properties of high-mass
stars, and IMF within existing uncertainties, and study the effects on the
evolution of the structural properties of GCs, and the BHs in GCs. We find that
variations in initial assumptions can set otherwise identical initial clusters
on completely different evolutionary paths, significantly affecting their
present observable properties, or even affecting the cluster's very survival to
the present. However, these changes usually do not affect the numbers or
properties of local BH--BH mergers. The only exception is that variations in
the assumed winds and IMF can change the masses and numbers of local BH--BH
mergers, respectively. All other variations (e.g., in initial binary properties
and binary fraction) leave the masses and numbers of locally merging BH--BH
binaries largely unchanged. This is in contrast to binary population synthesis
models for the field, where results are very sensitive to many uncertain
parameters in the initial binary properties and binary stellar-evolution
physics. We find that weak winds are required for producing GW150914-like
mergers from GCs at low redshifts. LVT151012 can be produced in GCs modeled
both with strong and weak winds. GW151226 is lower-mass than typical mergers
from GCs modeled with weak winds, but is similar to mergers from GCs modeled
with strong winds.


title: The $K_{n+5}$ and $K_{3^2,1^n}$ families are obstructions to $n$-apex

abstract:
  We give evidence in support of a conjecture that the $\nabla$Y$\nabla$
families of $K_{n+5}$ and $K_{3^2,1^n}$ are obstructions for the $n$-apex
property.


title:
Forecasting the Socio-Economic Impact of the Large Hadron Collider: a
  Cost-Benefit Analysis to 2025 and Beyond

abstract:
  In this paper we develop a cost-benefit analysis of a major research
infrastructure, the Large Hadron Collider (LHC), the highest-energy accelerator
in the world, currently operating at CERN. We show that the evaluation of
benefits can be made quantitative by estimating their welfare effects on
different types of agents. Four classes of direct benefits are identified,
according to the main social groups involved: (a) scientists; (b) students and
young researchers; (c) firms in the procurement chain and other organizations;
(d) the general public, including onsite and website visitors and other media
users. These benefits are respectively related to the knowledge output of
scientists; human capital formation; technological spillovers; and direct
cultural effects for the general public. Welfare effects for taxpayers can also
be estimated by the contingent valuation of the willingness to pay for a pure
public good for which there is no specific direct use (i.e., as non-use value).
Using a Monte Carlo approach, we estimate the conditional probability
distribution of costs and benefits for the LHC from 1993 until its planned
decommissioning in 2025, assuming a range of values for some critical
stochastic variables. We conservatively estimate that there is around a 90\%
probability that benefits exceed costs, with an expected net present value of
about 2.9 billion euro, not considering the unpredictable applications of
scientific discovery.

categories: physics.soc-ph hep-ex hep-ph physics.acc-ph


title: Conformal Manifolds in Four Dimensions and Chiral Algebras

abstract:
  Any N=2 superconformal field theory (SCFT) in four dimensions has a sector of
operators related to a two-dimensional chiral algebra containing a Virasoro
sub-algebra. Moreover, there are well-known examples of isolated SCFTs whose
chiral algebra is a Virasoro algebra. In this note, we consider the chiral
algebras associated with interacting N=2 SCFTs possessing an exactly marginal
deformation that can be interpreted as a gauge coupling (i.e., at special
points on the resulting conformal manifolds, free gauge fields appear that
decouple from isolated SCFT building blocks). At any point on these conformal
manifolds, we argue that the associated chiral algebras possess at least three
generators. In addition, we show that there are examples of SCFTs realizing
such a minimal chiral algebra: they are certain points on the conformal
manifold obtained by considering the low-energy limit of type IIB string theory
on the three complex-dimensional hypersurface singularity x_1^3+x_2^3+x_3^3+A
x_1x_2x_3+w^2=0. The associated chiral algebra is the A(6) theory of Feigin,
Feigin, and Tipunin. As byproducts of our work, we argue that (i) a collection
of isolated theories can be conformally gauged only if there is a SUSY moduli
space associated with the corresponding symmetry current moment maps in each
sector, and (ii) N=2 SCFTs with a>=c have hidden fermionic symmetries (in the
sense of fermionic chiral algebra generators).


title: Ab Initio Cosmological Simulations of CR7 as an Active Black Hole

abstract:
  We present the first ab initio cosmological simulations of a CR7-like object
which approximately reproduce the observed line widths and strengths. In our
model, CR7 is powered by a massive ($3.23 \times 10^7$ $M_\odot$) black hole
(BH) the accretion rate of which varies between $\simeq$ 0.25 and $\simeq$ 0.9
times the Eddington rate on timescales as short as 10$^3$ yr. Our model takes
into account multi-dimensional effects, X-ray feedback, secondary ionizations
and primordial chemistry. We estimate Ly-$\alpha$ line widths by
post-processing simulation output with Monte Carlo radiative transfer and
calculate emissivity contributions from radiative recombination and collisional
excitation. We find the luminosities in the Lyman-$\alpha$ and He II 1640
angstrom lines to be $5.0\times10^{44}$ and $2.4\times10^{43}$ erg s$^{-1}$,
respectively, in agreement with the observed values of $>$ $8.3\times10^{43}$
and $2.0\times10^{43}$ erg s$^{-1}$. We also find that the black hole heats the
halo and renders it unable to produce stars as required to keep the halo metal
free. These results demonstrate the viability of the BH hypothesis for CR7 in a
cosmological context. Assuming the BH mass and accretion rate that we find, we
estimate the synchrotron luminosity of CR7 to be $P \simeq 10^{40} - 10^{41}$
erg s$^{-1}$, which is sufficiently luminous to be observed in $\mu$Jy
observations and would discriminate this scenario from one where the luminosity
is driven by Population III stars.


title:
The distribution of class numbers in a special family of real quadratic
  fields

abstract:
  We investigate the distribution of class numbers in the family of real
quadratic fields $\mathbb{Q}(\sqrt{d})$ corresponding to fundamental
discriminants of the form $d=4m^2+1$, which we refer to as Chowla's family. Our
results show a strong similarity between the distribution of class numbers in
this family and that of class numbers of imaginary quadratic fields. As an
application of our results, we prove that the average order of the number of
quadratic fields in Chowla's family with class number $h$ is $(\log h)/2G$,
where $G$ is Catalan's constant. With minor modifications, one can obtain
similar results for Yokoi's family of real quadratic fields
$\mathbb{Q}(\sqrt{d})$, which correspond to fundamental discriminants of the
form $d=m^2+4$.


title:
Group classification of Schr\"odinger equations with position dependent
  mass

abstract:
  Maximal kinematical invariance groups of $2d$ Schr\"odinger equation with a
position dependent mass and arbitrary potential are classified. It is
demonstrated that there exist seven classes of such equations possessing
non-equivalent continuous symmetry group. Three of these classes include
arbitrary functions while the remaining ones are defined up to arbitrary
parameters. In particular, for the case of a constant mass the class missing in
the Boyer classification (Boyer C P 1974 Helv. Phys. Acta{\bf 47}, 450) is
indicated. A constructive test of (non)equivalence of a PDM system to a
constant mass system is proposed.


title:
Radio synchrotron emission from secondary electrons in
  interaction-powered supernovae

abstract:
  Several supernovae (SNe) with an unusually dense circumstellar medium (CSM)
have been recently observed at radio frequencies. Their radio emission is
powered by relativistic electrons that can be either accelerated at the SN
shock (primaries) or injected as a by-product (secondaries) of inelastic
proton-proton collisions. We investigate the radio signatures from secondary
electrons, by detailing a semi-analytical model to calculate the temporal
evolution of the distributions of protons, primary and secondary electrons.
With our formalism, we track the cooling history of all the particles that have
been injected into the emission region up to a given time, and calculate the
resulting radio spectra and light curves. For a SN shock propagating through
the progenitor wind, we find that secondary electrons control the early radio
signatures, but their contribution decays faster than that of primary
electrons. This results in a flattening of the light curve at a given radio
frequency that depends only upon the radial profiles of the CSM density and of
the shock velocity, $v_0$. The relevant transition time at the peak frequency
is $\sim 190 \, K_{\rm ep,-3}^{-1} A_{\rm w, 16} \beta_{0, -1.5}^{-2}\,{\rm
d}$, where $A_{\rm w}$ is the wind mass-loading parameter, $\beta_0=v_0/c$ and
$K_{\rm ep}$ is the electron-to-proton ratio of accelerated particles. We
explicitly show that late peak times at 5 GHz (i.e., $t_{\rm pk} \gtrsim
300-1000$ d) suggest a shock wave propagating in a dense wind ($A_{\rm w}
\gtrsim 10^{16}-10^{17}$ gr cm$^{-1}$), where secondary electrons are likely to
power the observed peak emission.


title: Counter-fitting Word Vectors to Linguistic Constraints

abstract:
  In this work, we present a novel counter-fitting method which injects
antonymy and synonymy constraints into vector space representations in order to
improve the vectors' capability for judging semantic similarity. Applying this
method to publicly available pre-trained word vectors leads to a new state of
the art performance on the SimLex-999 dataset. We also show how the method can
be used to tailor the word vector space for the downstream task of dialogue
state tracking, resulting in robust improvements across different dialogue
domains.


title:
Frequency-hiding Dependency-preserving Encryption for Outsourced
  Databases

abstract:
  The cloud paradigm enables users to outsource their data to computationally
powerful third-party service providers for data management. Many data
management tasks rely on the data dependencies in the outsourced data. This
raises an important issue of how the data owner can protect the sensitive
information in the outsourced data while preserving the data dependencies. In
this paper, we consider functional dependency FD, an important type of data
dependency. We design a FD-preserving encryption scheme, named F2, that enables
the service provider to discover the FDs from the encrypted dataset. We
consider the frequency analysis attack, and show that the F2 encryption scheme
can defend against the attack under Kerckhoff's principle with provable
guarantee. Our empirical study demonstrates the efficiency and effectiveness of
F2.


title: Extremal results for random discrete structures

abstract:
  We study thresholds for extremal properties of random discrete structures. We
determine the threshold for Szemer\'edi's theorem on arithmetic progressions in
random subsets of the integers and its multidimensional extensions and we
determine the threshold for Tur\'an-type problems for random graphs and
hypergraphs. In particular, we verify a conjecture of Kohayakawa, \L uczak, and
R\"odl for Tur\'an-type problems in random graphs. Similar results were
obtained by Conlon and Gowers.


title: Personalized Cancer Therapy Design: Robustness vs. Optimality

abstract:
  Intermittent Androgen Suppression (IAS) is a treatment strategy for delaying
or even preventing time to relapse of advanced prostate cancer. IAS consists of
alternating cycles of therapy (in the form of androgen suppression) and
off-treatment periods. The level of prostate specific antigen (PSA) in a
patient's serum is frequently monitored to determine when the patient will be
taken off therapy and when therapy will resume. In spite of extensive recent
clinical experience with IAS, the design of an ideal protocol for any given
patient remains one of the main challenges associated with effectively
implementing this therapy. We use a threshold-based policy for optimal IAS
therapy design that is parameterized by lower and upper PSA threshold values
and is associated with a cost metric that combines clinically relevant measures
of therapy success. We apply Infinitesimal Perturbation Analysis (IPA) to a
Stochastic Hybrid Automaton (SHA) model of prostate cancer evolution under IAS
and derive unbiased estimators of the cost metric gradient with respect to
various model and therapy parameters. These estimators are subsequently used
for system analysis. By evaluating sensitivity estimates with respect to
several model parameters, we identify critical parameters and demonstrate that
relaxing the optimality condition in favor of increased robustness to modeling
errors provides an alternative objective to therapy design for at least some
patients.


title:
Uncovering Longitudinal Healthcare Utilization from Patient-Level
  Medical Claims Data

abstract:
  The objective of this study is to introduce methodology for studying
longitudinal claims data observed at the patient level, with inference on the
heterogeneity of healthcare utilization behaviors within large healthcare
systems such as Medicaid. The proposed approach is model-based, allowing for
visualization of longitudinal utilization behaviors using simple stochastic
graphical networks. The approach is general, providing a framework for the
study of other chronic conditions wherever longitudinal healthcare utilization
data are available. Our methods are inspired by and applied to patient-level
Medicaid claims for asthma-diagnosed children diagnosed observed over a period
of five years, with a comparison of two neighboring states, Georgia and North
Carolina.


title:
A simple tool for bounding the deviation of random matrices on geometric
  sets

abstract:
  Let $A$ be an isotropic, sub-gaussian $m \times n$ matrix. We prove that the
process $Z_x := \|Ax\|_2 - \sqrt m \|x\|_2$ has sub-gaussian increments. Using
this, we show that for any bounded set $T \subseteq \mathbb{R}^n$, the
deviation of $\|Ax\|_2$ around its mean is uniformly bounded by the Gaussian
complexity of $T$. We also prove a local version of this theorem, which allows
for unbounded sets. These theorems have various applications, some of which are
reviewed in this paper. In particular, we give a new result regarding model
selection in the constrained linear model.


title: Large Peg-Army Maneuvers

abstract:
  Despite its long history, the classical game of peg solitaire continues to
attract the attention of the scientific community. In this paper, we consider
two problems with an algorithmic flavour which are related with this game,
namely Solitaire-Reachability and Solitaire-Army. In the first one, we show
that deciding whether there is a sequence of jumps which allows a given initial
configuration of pegs to reach a target position is NP-complete. Regarding
Solitaire-Army, the aim is to successfully deploy an army of pegs in a given
region of the board in order to reach a target position. By solving an
auxiliary problem with relaxed constraints, we are able to answer some open
questions raised by Cs\'ak\'any and Juh\'asz (Mathematics Magazine, 2000). To
appreciate the combinatorial beauty of our solutions, we recommend to visit the
gallery of animations provided at http://solitairearmy.isnphard.com.


title: Wave mechanics of the hydrogen atom

abstract:
  The hydrogen atom is a system amenable to an exact treatment within
Schroedinger's formulation of quantum mechanics according to coordinates in
four systems -- spherical polar, paraboloidal, ellipsoidal and spheroconical
coordinates; the latter solution is reported for the first time. Applications
of these solutions include angular momenta, a quantitative calculation of the
absorption spectrum and accurate plots of surfaces of amplitude functions. The
shape of an amplitude function, and even the quantum numbers in a particular
set to specify such an individual function, depend on the coordinates in a
particular chosen system, and are therefore artefacts of that particular
coordinate representation within wave mechanics. All discussion of atomic or
molecular properties based on such shapes or quantum numbers therefore lacks
general significance


title:
Particle diffusion and localized acceleration in inhomogeneous AGN jets
  - Part II: stochastic variation

abstract:
  We study the stochastic variation of blazar emission under a 2-D spatially
resolved leptonic jet model we previously developed. Random events of particle
acceleration and injection in small zones within the emission region are
assumed to be responsible for flux variations. In addition to producing
spectral energy distributions that describe the observed flux of Mrk 421, we
further analyze the timing properties of the simulated light curves, such as
the power spectral density (PSD) at different bands, flux-flux correlations, as
well as the cross-correlation function between X-rays and TeV {\gamma}-rays. We
find spectral breaks in the PSD at a timescale comparable to the dominant
characteristic time scale in the system, which is usually the pre-defined decay
time scale of an acceleration event. Cooling imposes a delay, and so PSDs taken
at lower energy bands in each emission component (synchrotron or inverse
Compton) generally break at longer timescales. The flux-flux correlation
between X-rays and TeV {\gamma}-rays can be either quadratic or linear,
depending on whether or not there are large variation of the injection into the
particle acceleration process. When the relationship is quadratic, the TeV
flares lag the X-ray flares, and the optical & GeV flares are large enough to
be comparable to the ones in X-ray. When the relationship is linear, the lags
are insignificant, and the optical & GeV flares are small.


title: Magnetic transitions in the topological magnon insulator Cu(1,3-bdc)

abstract:
  Topological magnon insulators are a new class of magnetic materials that
possess topologically nontrivial magnon bands. As a result, magnons in these
materials display properties analogous to those of electrons in topological
insulators. Here, we present magnetization, specific heat, and neutron
scattering measurements of the ferromagnetic kagome magnet Cu(1,3-bdc). Our
measurements provide a detailed description of the magnetic structure and
interactions in this material, and confirm that it is an ideal prototype for
topological magnon physics in a system with a simple spin Hamiltonian.


title:
Air-sea interaction in tropical atmosphere: influence of ocean mixing on
  atmospheric processes

abstract:
  One the major factors determining the development and evolution of
atmospheric convection is the sea surface temperature and its variability.
Results of this thesis show that state of atmospheric convection impacts the
diurnal distribution of thermal energy in the upper ocean. Under calm and clear
sky conditions a shallow warm layer of several meters depth develops on the
surface of the ocean. This warm layer drives an anomalous flux from the ocean
to the atmosphere. A novel Kelvin wave trajectory database based on satellite
data is introduced in this study. The investigation of its data shows that
substantial fraction of Kelvin waves is initiated as a result of interaction
with another Kelvin wave. Two distinct categories are defined and analyzed: the
two- and multiple Kelvin wave initiations, and a spin off initiation. Results
show that primary forcing of such waves are high diurnal cycle and/or increased
wind speed and latent heat flux at the ocean surface. Variability of the ocean
surface and subsurface along Kelvin wave trajectories over Indian Ocean is
investigated: wind speed and latent heat flux increase and a sea surface
temperature anomaly decreases during a wave passage. It is also shown that
Kelvin waves are longitude-diurnal cycle phase locked over the Maritime
Continent. This cycle phase locking is such that it agrees with mean, local
diurnal cycle of convection in the atmosphere. The strength of the
longitude-diurnal cycle phase locking differs between non-blocked Kelvin waves,
which make successful transition over the Maritime Continent, and blocked waves
that terminate within it. The distance between the islands of Sumatra and
Borneo agrees with the distance travelled by an average Kelvin wave in one day.
This suggests that the Maritime Continent may act as a filter, favoring
successful propagation waves, which are in phase with the local diurnal cycle
of convection.


title: Pointer Quantum PCPs and Multi-Prover Games

abstract:
  The quantum PCP (QPCP) conjecture states that all problems in QMA, the
quantum analogue of NP, admit quantum verifiers that only act on a constant
number of qubits of a polynomial size quantum proof and have a constant gap
between completeness and soundness. Despite an impressive body of work trying
to prove or disprove the quantum PCP conjecture, it still remains widely open.
The above-mentioned proof verification statement has also been shown equivalent
to the QMA-completeness of the Local Hamiltonian problem with constant relative
gap. Nevertheless, unlike in the classical case, no equivalent formulation in
the language of multi-prover games is known.
  In this work, we propose a new type of quantum proof systems, the Pointer
QPCP, where a verifier first accesses a classical proof that he can use as a
pointer to which qubits from the quantum part of the proof to access. We define
the Pointer QPCP conjecture, that states that all problems in QMA admit quantum
verifiers that first access a logarithmic number of bits from the classical
part of a polynomial size proof, then act on a constant number of qubits from
the quantum part of the proof, and have a constant gap between completeness and
soundness. We define a new QMA-complete problem, the Set Local Hamiltonian
problem, and a new restricted class of quantum multi-prover games, called CRESP
games. We use them to provide two other equivalent statements to the Pointer
QPCP conjecture: the Set Local Hamiltonian problem with constant relative gap
is QMA-complete; and the approximation of the maximum acceptance probability of
CRESP games up to a constant additive factor is as hard as QMA. This is the
first equivalence between a quantum PCP statement and the inapproximability of
quantum multi-prover games.


title: The Graph of Our Mind

abstract:
  Graph theory in the last two decades penetrated sociology, molecular biology,
genetics, chemistry, computer engineering, and numerous other fields of
science. One of the more recent areas of its applications is the study of the
connections of the human brain. By the development of diffusion magnetic
resonance imaging (diffusion MRI), it is possible today to map the connections
between the 1-1.5 cm$^2$ regions of the gray matter of the human brain. These
connections can be viewed as a graph: the vertices are the anatomically
identified regions of the gray matter, and two vertices are connected by an
edge if the diffusion MRI-based workflow finds neuronal fiber tracts between
these areas. This way we can compute 1015-vertex graphs with tens of thousands
of edges. In a previous work, we have analyzed the male and female braingraphs
graph-theoretically, and we have found statistically significant differences in
numerous parameters between the sexes: the female braingraphs are better
expanders, have more edges, larger bipartition widths, and larger vertex cover
than the braingraphs of the male subjects. Our previous study has applied the
data of 96 subjects; here we present a much larger study of 426 subjects. Our
data source is an NIH-founded project, the "Human Connectome Project (HCP)"
public data release. As a service to the community, we have also made all of
the braingraphs computed by us from the HCP data publicly available at the
\url{http://braingraph.org} for independent validation and further
investigations.


title: Parallel mean curvature tori in $CP^{2}$ and $CH^{2}$

abstract:
  We explicitly determine tori that have a parallel mean curvature vector, both
in the complex projective plane and the complex hyperbolic plane


title:
Phase super-resolution with N00N states generated by on demand
  single-photon sources

abstract:
  Multi-photon entangled states such as `N00N states' have attracted a lot of
attention because of their possible application in high-precision phase
measurements. So far, N00N states have been generated by spontaneous parametric
down-conversion sources and by mixing quantum and classical light on a beam
splitter. However, single-photon on demand sources promise to be more efficient
and scalable than down-conversion sources which are probabilistic in nature.
Here, we demonstrate super-resolving phase measurements based on two-photon
N00N states generated by a quantum dot single-photon source utilizing the
Hong-Ou-Mandel effect on a beam splitter. The quantum dot was excited through a
two-photon resonant excitation scheme. Using a $\pi$-pulse, this results in the
deterministic generation of indistinguishable single photons from both, the
biexciton and exciton radiative recombination processes. Launching either type
of the photons into both inputs of an interferometer, phase super-resolution,
i.e. an interference fringe spacing with doubled rate relative to the single
photon rate has been observed for both transitions. Interference visibilities
of $V_{N=2,\mathit{XX}}=0.54\pm0.01$ for the biexciton and
$V_{N=2,\mathit{X}}=0.46\pm0.02$ for the exciton transition have been obtained,
respectively.


title: Dispersion as a survival strategy

abstract:
  We consider stochastic growth models to represent population subject to
catastrophes. We analyze the subject from different set ups considering or not
spatial restrictions, whether dispersion is a good strategy to increase the
population viability. We find out it strongly depends on the effect of a
catastrophic event, the spatial constraints of the environment and the
probability that each exposed individual survives when a disaster strikes.


title: Gating a single-molecule transistor with individual atoms

abstract:
  Transistors, regardless of their size, rely on electrical gates to control
the conductance between source and drain contacts. In atomic-scale transistors,
this conductance is exquisitely sensitive to single electrons hopping via
individual orbitals. Single-electron transport in molecular transistors has
been previously studied using top-down approaches to gating, such as
lithography and break junctions. But atomically precise control of the gate -
which is crucial to transistor action at the smallest size scales - is not
possible with these approaches. Here, we used individual charged atoms,
manipulated by a scanning tunnelling microscope, to create the electrical gates
for a single-molecule transistor. This degree of control allowed us to tune the
molecule into the regime of sequential single-electron tunnelling, albeit with
a conductance gap more than one order of magnitude larger than observed
previously. This unexpected behaviour arises from the existence of two
different orientational conformations of the molecule, depending on its charge
state. Our results show that strong coupling between these charge and
conformational degrees of freedom leads to new behaviour beyond the established
picture of single-electron transport in atomic-scale transistors.


title: Status of Dual-readout R&D for a linear collider in T1015 Collaboration

abstract:
  The hadronic energy resolution required for an hadronic operating at lepton
collider is at the limits or even exceeds that obtained with traditional
techniques. Furthermore, it is a well established fact that the presence of an
electromagnetic section in front of an hadron calorimeter, as occurs in the
layouts of the majority of detectors operating at a collider, would deteriorate
the hadronic energy resolution of the device. The novel $ADRIANO$ technology
(\textit{A Dual-readout Integrally Active Non-segmented Option}), currently
under development at Fermilab, overcomes the above limitations by complementing
an integrally active calorimeter with the dual-readout technique. Detailed
Monte Carlo studies indicate that the energy resolution is in the
$25\%/\sqrt{E}$ - $38\%/\sqrt{E}$ interval with a linear response of the
detector up to an energy of 200 GeV. A baseline configuration is chosen with an
estimated energy resolution of $\sigma(E)/E\approx30\%/\sqrt{E}$. Several
prototypes have been built by \textit{T1015} Collaboration at Fermilab, to
explore the effect of modifications of the layout from the baseline
configuration. Preliminary results from several test beams at the
\textit{Fermilab Test Beam Facility} (FTBF) of $\sim1\lambda_{I}$ prototypes
are presented. Future prospects with ultra-heavy glass are, also, summarized.


title: Vaccination and Complex Social Dynamics

abstract:
  Vaccination and outbreak monitoring are essential tools for preventing and
minimizing outbreaks of infectious diseases. Targeted strategies, where the
individuals most important for monitoring or preventing outbreaks are selected
for intervention, offer a possibility to significantly improve these measures.
Although targeted strategies carry a strong potential, identifying optimal
target groups remains a challenge. Here we consider the problem of identifying
target groups based on digital communication networks (telecommunication,
online social media) in order to predict and contain an infectious disease
spreading on a real-world person-to-person network of more than 500
individuals. We show that target groups for efficient outbreak monitoring can
be determined based on both telecommunication and online social network
information. In case of vaccination the information regarding the digital
communication networks improves the efficacy for short-range disease
transmissions but, surprisingly, performance is severely reduced in the case of
long-range transmission. These results are robust with respect to the strategy
used to identify targeted individuals and time-gap between identification of
targets and the intervention. Thus, we demonstrate that data available from
telecommunication and online social networks can greatly improve epidemic
control measures, but it is important to consider the details of the pathogen
spreading mechanism when such policies are applied.


title:
Second harmonic light scattering induced by defects in the twist-bend
  nematic phase of liquid crystal dimers

abstract:
  The nematic twist-bend ($\mathrm{N_{TB}}$) phase, exhibited by certain
thermotropic liquid crystalline (LC) dimers, represents a new orientationally
ordered mesophase -- the first distinct nematic variant discovered in many
years. The $\mathrm{N_{TB}}$ phase is distinguished by a heliconical winding of
the average molecular long axis (director) with a remarkably short (nanoscale)
pitch and, in systems of achiral dimers, with an equal probability to form
right- and left-handed domains. The $\mathrm{N_{TB}}$ structure thus provides
another fascinating example of spontaneous chiral symmetry breaking in nature.
The order parameter driving the formation of the heliconical state has been
theoretically conjectured to be a polarization field, deriving from the bent
conformation of the dimers, that rotates helically with the same nanoscale
pitch as the director field. It therefore presents a significant challenge for
experimental detection. Here we report a second harmonic light scattering
(SHLS) study on two achiral, $\mathrm{N_{TB}}$-forming LCs, which is sensitive
to the polarization field due to micron-scale distortion of the helical
structure associated with naturally-occurring textural defects. These defects
are parabolic focal conics of smectic-like "pseudo-layers", defined by planes
of equivalent phase in a coarse-grained description of the $\mathrm{N_{TB}}$
state. Our SHLS data are explained by a coarse-grained free energy density that
combines a Landau-deGennes expansion of the polarization field, the elastic
energy of a nematic, and a linear coupling between the two.


title:
LiDAR Ground Filtering Algorithm for Urban Areas Using Scan Line Based
  Segmentation

abstract:
  This paper addresses the task of separating ground points from airborne LiDAR
point cloud data in urban areas. A novel ground filtering method using scan
line segmentation is proposed here, which we call SLSGF. It utilizes the scan
line information in LiDAR data to segment the LiDAR data. The similarity
measurements are designed to make it possible to segment complex roof
structures into a single segment as much as possible so the topological
relationships between the roof and the ground are simpler, which will benefit
the labeling process. In the labeling process, the initial ground segments are
detected and a coarse to fine labeling scheme is applied. Data from ISPRS 2011
are used to test the accuracy of SLSGF; and our analytical and experimental
results show that this method is computationally-efficient and
noise-insensitive, thereby making a denoising process unnecessary before
filtering.


title: Client-CASH: Protecting Master Passwords against Offline Attacks

abstract:
  Offline attacks on passwords are increasingly commonplace and dangerous. An
offline adversary is limited only by the amount of computational resources he
or she is willing to invest to crack a user's password. The danger is
compounded by the existence of authentication servers who fail to adopt proper
password storage practices like key-stretching. Password managers can help
mitigate these risks by adopting key stretching procedures like hash iteration
or memory hard functions to derive site specific passwords from the user's
master password on the client-side. While key stretching can reduce the offline
adversary's success rate, these procedures also increase computational costs
for a legitimate user. Motivated by the observation that most of the password
guesses of the offline adversary will be incorrect, we propose a client side
cost asymmetric secure hashing scheme (Client-CASH). Client-CASH randomizes the
runtime of client-side key stretching procedure in a way that the expected
computational cost of our key derivation function is greater when run with an
incorrect master password. We make several contributions. First, we show how to
introduce randomness into a client-side key stretching algorithms through the
use of halting predicates which are selected randomly at the time of account
creation. Second, we formalize the problem of finding the optimal running time
distribution subject to certain cost constraints for the client and certain
security constrains on the halting predicates. Finally, we demonstrate that
Client-CASH can reduce the adversary's success rate by up to $21\%$. These
results demonstrate the promise of the Client-CASH mechanism.


title:
Algebraic approach and coherent states for a relativistic quantum
  particle in cosmic string spacetime

abstract:
  We study a relativistic quantum particle in cosmic string spacetime in the
presence of a uniform magnetic field and a Coulomb-type scalar potential. It is
shown that the radial part of this problem possesses the $su(1,1)$ symmetry. We
obtain the energy spectrum and eigenfunctions of this problem by using two
algebraic methods: the Schr\"odinger factorization and the tilting
transformation. Finally, we give the explicit form of the relativistic coherent
states for this problem.


title:
Qualitative analysis of three-wave interaction with periodic boundary
  condition

abstract:
  First, for 3WRI with positive wave energy, we present a regularity theorem
for all spatial dimension. Second, for 3WRI with negative wave energy, we
present a class of solution in general spatial dimension that will blow up in
finite time. Moreover, a complete classification of spatial uniform solution is
given for this particular system.


title:
Discrete phase-space mappings, tomographic condition and permutation
  invariance

abstract:
  We analyze different families of discrete maps\ in the N-qubit systems in the
context of the permutation invariance. We prove that the tomographic condition
imposed on the self-dual (Wigner) map is incompatible with the requirement of
the invariance under particle permutations, which makes it impossible to
project the Wootters-like Wigner function into the space of symmetric
measurements. We also provide several \textit{explicit} forms of the self-dual
mappings: a) tomographic and b) permutation invariant \ and analyze the
symmetric projection in the latter case.


title:
Influence of network topology on the swelling of polyelectrolyte
  nanogels

abstract:
  It is well-known that the swelling behavior of ionic nanogels depends on
their cross-link density, however it is unclear how different topologies should
affect the response of the polyelectrolyte network. Here we perform Monte Carlo
simulations to obtain the equilibrium properties of ionic nanogels as a
function of salt concentration $C_s$ and the fraction $f$ of ionizable groups
in a polyelectrolyte network formed by cross-links of functionality $z$. Our
results indicate that the network with cross-links of low connectivity result
in nanogel particles with higher swelling ratios. We also confirm a de-swelling
effect of salt on nanogel particles.


title: Combining cluster number counts and galaxy clustering

abstract:
  The abundance of clusters and the clustering of galaxies are two of the
important cosmological probes for current and future large scale surveys of
galaxies, such as the Dark Energy Survey. In order to combine them one has to
account for the fact that they are not independent quantities, since they probe
the same density field. It is important to develop a good understanding of
their correlation in order to extract parameter constraints. We present a
detailed modelling of the joint covariance matrix between cluster number counts
and the galaxy angular power spectrum. We employ the framework of the halo
model complemented by a Halo Occupation Distribution model (HOD). We
demonstrate the importance of accounting for non-Gaussianity to produce
accurate covariance predictions. Indeed, we show that the non-Gaussian
covariance becomes dominant at small scales, low redshifts or high cluster
masses. We discuss in particular the case of the super-sample covariance (SSC),
including the effects of galaxy shot-noise, halo second order bias and
non-local bias. We demonstrate that the SSC obeys mathematical inequalities and
positivity. Using the joint covariance matrix and a Fisher matrix methodology,
we examine the prospects of combining these two probes to constrain
cosmological and HOD parameters. We find that the combination indeed results in
noticeably better constraints, with improvements of order 20\% on cosmological
parameters compared to the best single probe, and even greater improvement on
HOD parameters, with reduction of error bars by a factor 1.4-4.8. This happens
in particular because the cross-covariance introduces a synergy between the
probes on small scales. We conclude that accounting for non-Gaussian effects is
required for the joint analysis of these observables in galaxy surveys.


title: Nucleon Resonance Physics

abstract:
  Recent results of meson photo-production at the existing electron machines
with polarized real photon beams and the measurement of polarization
observables of the final state baryons have provided high precision data that
led to the discovery of new excited nucleon and $\Delta$ states using
multi-channel partial wave analyses procedures. The internal structure of
several prominent excited states has been revealed employing meson
electroproduction processes. On the theoretical front, lattice QCD is now
predicting the baryon spectrum with very similar characteristics as the
constituent quark model, and continuum QCD, such as is represented in the
Dyson-Schwinger Equations approach and in light front relativistic quark
models, describes the non-perturbative behavior of resonance excitations at
photon virtuality of $Q^2 > 1.5GeV^2$. In this talk I discuss the need to
continue a vigorous program of nucleon spectroscopy and the study of the
internal structure of excited states as a way to reveal the effective degrees
of freedom underlying the excited states and their dependence on the distance
scale probed.


title: European and Asian Greeks for exponential L\'evy processes

abstract:
  In this paper we give easy-to-implement closed expressions for European and
Asian Greeks for general L^{2}-payoff functions and underlying assets in an
exponential L\'evy process model with nonvanishing Brownian motion part. The
results are based on Hilbert space valued Malliavin Calculus and extend
previous results from the literature. Numerical experiments suggest, that in
the case of an continuous payoff function, a combination of Malliavin Monte
Carlo Greeks and the finite difference method has a better convergence
behavior, whereas in the case of discontinuous payoff functions, the Malliavin
Monte Carlo method clearly is the superior method compared to the finite
difference approach, and for first- and second order Greeks.


title: Doubly-nonparametric generalized additive models

abstract:
  The popular generalized additive model framework is extended to allow both
the mean curves and the response distribution to be nonparametric. The approach
is demonstrated to be a flexible yet parsimonious tool for data analysis in its
own right, as well as being a useful tool for model selection and diagnosis in
the classical generalized additive model framework. Finite-sample performance
of the method is examined via various simulation settings and the method is
illustrated on two data analysis examples.


title:
Structural characterisation of tin fluorophosphate glasses doped with
  Er2O3

abstract:
  EXAFS and confocal Raman microscopy have been used to study
50SnF2.(20-x)SnO.30P2O5.xEr2O3 (x=0, 0.1, 0.25) glasses. EXAFS data reveal an
average coordination of Sn to O of 1.5 in both undoped glass and Er-doped glass
samples. The first coordination sphere of Er in glasses doped with Er2O3 was
found to have 9 F atom neighbours at an average bond length of 2.292+/-0.005
{\AA}, indicating that Er preferentially bonds with F. Raman spectra clearly
show the emergence of orthophosphate Q0 units on addition of Er2O3. The
saturation of Er solubility is found to be between 0.25 and 0.5 mol$\%$ Er2O3.
An increase of the glass transition temperature from $\sim$80{\deg}C in undoped
glass to $\sim$87{\deg}C in samples doped with 0.25 mol$\%$ Er2O3 was also
observed. This process is accompanied by an increase in the difference between
the crystallisation and glass transition temperatures, which is usually
associated with improved thermal stability of the glass.


title:
Asymptotic joint distribution of the extremities of a random Young
  diagram and enumeration of graphical partitions

abstract:
  An integer partition of $n$ is a decreasing sequence of positive integers
that add up to $[n]$. Back in $1979$ Macdonald posed a question about the limit
value of the probability that two partitions chosen uniformly at random, and
independently of each other, are comparable in terms of the dominance order. In
$1982$ Wilf conjectured that the uniformly random partition is a size-ordered
degree sequence of a simple graph with the limit probability $0$. In $1997$ we
showed that in both, seemingly unrelated, cases the limit probabilities are
indeed zero, but our method left open the problem of convergence rates. The
main result in this paper is that each of the probabilities is $e^{-0.11\log
n/\log\log n}$, at most. A key element of the argument is a local limit
theorem, with convergence rate, for the joint distribution of the
$[n^{1/4-\varepsilon}]$ tallest columns and the $[n^{1/4-\varepsilon}]$ longest
rows of the Young diagram representing the random partition.


title: Lectures on Matrix Field Theory I

abstract:
  The subject of matrix field theory involves matrix models, noncommutative
geometry, fuzzy physics and noncommutative field theory and their interplay. In
these lectures, a lot of emphasis is placed on the matrix formulation of
noncommutative and fuzzy spaces, and on the non-perturbative treatment of the
corresponding field theories. In particular, the phase structure of
noncommutative $\phi^4$ theory is treated in great detail, and an introduction
to noncommutative gauge theory is given.