title: The dimension of projections of fractal percolations

abstract:
  \emph{Fractal percolation} or \emph{Mandelbrot percolation} is one of the
most well studied families of random fractals.
  In this paper we study some of the geometric measure theoretical properties
(dimension of projections and structure of slices) of these random sets.
Although random, the geometry of those sets is quite regular. Our results imply
that, denoting by $E\subset \mathbb{R}^2$ a typical realization of the fractal
percolation on the plane, {itemize}
  If $\dim_{\rm H}E<1$ then for \textbf{all}lines $\ell$ the orthogonal
projection $E_\ell$ of $E$ to $\ell$ has the same Hausdorff dimension as $E$,
  If $\dim_{\rm H}E>1$ then for any smooth real valued function $f$ which is
strictly increasing in both coordinates, the image $f(E)$ contains an interval.
{itemize} The second statement is quite interesting considering the fact that
$E$ is almost surely a Cantor set (a {\it random dust}) for a large part of the
parameter domain, see \cite{Chayes1988}. Finally, we solve a related problem
about the existence of an interval in the algebraic sum of $d\geq 2$
one-dimensional fractal percolations.


title: Bulk viscosity of hot dense Quark matter in PNJL model

abstract:
  Starting from the Kubo formula and the the QCD low energy theorem, we study
the the bulk viscosity of hot dense quark matter in the PNJL model from the
equation of state . We show that the bulk viscosity has a sharp peak near the
chiral phase transition, and the ratio of bulk viscosity over entropy rises
dramatically in the vicinity of the phase transition. These results agrees with
that from lattice and other model calculations. In addition, we show that the
increase of chemical potential raises the bulk viscosity.


title: Is there a third order phase transition for supercritical fluids?

abstract:
  We prove that according to Molecular Dynamics (MD) simulations of liquid
mixtures of Lennard-Jones (L-J) particles, there is no third order phase
transition in the supercritical regime beyond Andrew's critical point. This
result is in open contrast with recent theoretical studies and experiments
which instead suggest not only its existence but also its universality
regarding the chemical nature of the fluid. We argue that our results are solid
enough to go beyond the limitations of MD and the generic character of L-J
models, thus suggesting a rather smooth liquid-vapor thermodynamic behavior of
fluids in supercritical regime.


title: Projections of fractal percolations

abstract:
  In this paper we study the radial and orthogonal projections and the distance
sets of the random Cantor sets $E\subset \mathbb{R}^2 $ which are called
Mandelbrot percolation or percolation fractals. We prove that the following
assertion holds almost surely: if the Hausdorff dimension of $E$ is greater
than 1 then the orthogonal projection to \textbf{every} line, the radial
projection with \textbf{every} center, and distance set from \textbf{every}
point contain intervals.


title:
Velocities and Linewidths in the Network and Cell Interiors of a Polar
  Coronal Hole, Compared with Quiet Sun

abstract:
  The relative Doppler velocities and linewidths in a polar coronal hole and
the nearby quiet-Sun region have been obtained from the {\it Solar and
Heliospheric Observatory} (SOHO)/{\it Coronal Diagnostic Spectrometer} (CDS)
observations using emission lines originating at different heights in the solar
atmosphere from the lower transition region (TR) to the low solar corona. The
observed region is separated into the network and the cell interior and the
behavior of the above parameters were examined in the different regions. It has
been found that the histograms of Doppler velocity and width are generally
broader in the cell interior as compared to the network. The histograms of
Doppler velocities of the network and cell interior do not show significant
difference in most cases. However, in the case of the quiet Sun, the Doppler
velocities of the cell interior are more blueshifted than those of the network
for the lowermost line He {\sc ii} 304 {\AA}, and an opposite behavior is seen
for the uppermost line Mg {\sc ix} 368 {\AA}. The histograms of line width show
that the network--cell difference is more prominent in the coronal hole. The
network has significantly larger linewidth than the cell interior for the
lowermost TR line He {\sc ii} 304 {\AA} for the quiet Sun. For coronal hole,
this is true for the three lower TR lines He {\sc ii} 304 {\AA}, O {\sc iii}
599 {\AA}, and O {\sc v} 630 {\AA}. Also obtained are the correlations between
the relative Doppler velocity and the width. A mild positive correlation is
found for the lowermost transition region line He {\sc ii} 304 {\AA} which
further decreases or become insignificant for the intermediate lines. For the
low coronal line, Mg {\sc ix} 368 {\AA}, the correlation becomes strongly
negative.


title: Renormalization group flow and symmetry restoration in de Sitter space

abstract:
  We compute the renormalization group flow of O(N) scalar field theories in de
Sitter space using nonperturbative renormalization group techniques in the
local potential approximation. We obtain the flow of the effective potential on
superhorizon scales for arbitrary space-time dimension D=d+1. We show that, due
to strong infrared fluctuations, the latter is qualitatively similar to the
corresponding one in Euclidean space with D=0. It follows that spontaneously
broken symmetries are radiatively restored in any space-time dimension and for
any value of N.


title: The geometry of fractal percolation

abstract:
  A well studied family of random fractals called fractal percolation is
discussed. We focus on the projections of fractal percolation on the plane. Our
goal is to present stronger versions of the classical Marstrand theorem, valid
for almost every realization of fractal percolation. The extensions go in three
directions: {itemize} the statements work for all directions, not almost all,
the statements are true for more general projections, for example radial
projections onto a circle, in the case $\dim_H >1$, each projection has not
only positive Lebesgue measure but also has nonempty interior. {itemize}


title:
Real-space renormalization group method for quantum 1/2 spins on the
  pyrochlore lattice

abstract:
  A simple phenomenological real-space renormalization group method for quantum
Heisenberg spins with nearest and next nearest neighbour interactions on a
pyrochlore lattice is presented. Assuming a scaling law for the order parameter
of two clusters of different sizes a set of coupled equations that gives the
fixed points of the renormalization group transformation and, thus, the
critical temperatures and ordered phases of the system is found. The particular
case of spins $\frac{1}{2}$ is studied in detail. Furthermore, to simplify the
mathematical details, from all the possible phases arising from the
renormalization group transformation, only those phases in which the magnetic
lattice is commensurate with a subdivision of the crystal lattice into four
interlocked fcc sublattices are considered. These correspond to a quantum spin
liquid, ferromagnetic order, or non-collinear order in which the total magnetic
moment of a tetrahedral unit is zero. The corresponding phase diagram is
constructed and the differences with respect to the classical model are
analysed. It is found that this method reproduces fairly well the phase diagram
of the pyrochlore lattice under the aforementioned constrains.


title: Metastable electron-pair states in a two-dimensional crystal

abstract:
  We study possible quantum states of two correlated electrons in a
two-dimensional crystal and find a metastable energy band of the electron pair
between the two lowest single-electron bands. These metastable states result
from the interplay of electron correlations and the strength of the crystal
potential. The two paired electrons are bound in the same unit cell in relative
coordinates with an average distance between them about one third of the
crystal period. Furthermore, we show how such electron-pairs can be stabilized
in a many-electron system.


title: Generalized Iterative Annealing Model for the action of RNA chaperones

abstract:
  As a consequence of the rugged landscape of RNA molecules their folding is
described by the kinetic partitioning mechanism according to which only a small
fraction ($\phi_F$) reaches the folded state while the remaining fraction of
molecules is kinetically trapped in misfolded intermediates. The transition
from the misfolded states to the native state can far exceed biologically
relevant time. Thus, RNA folding in vivo is often aided by protein cofactors,
called RNA chaperones, that can rescue RNAs from a multitude of misfolded
structures. We consider two models, based on chemical kinetics and chemical
master equation, for describing assisted folding. In the passive model,
applicable for class I substrates, transient interactions of misfolded
structures with RNA chaperones alone are sufficient to destabilize the
misfolded structures, thus entropically lowering the barrier to folding. For
this mechanism to be efficient the intermediate ribonucleoprotein (RNP) complex
between collapsed RNA and protein cofactor should have optimal stability. We
also introduce an active model (suitable for stringent substrates with small
$\phi_F$), which accounts for the recent experimental findings on the action of
CYT-19 on the group I intron ribozyme, showing that RNA chaperones does not
discriminate between the misfolded and the native states. In the active model,
the RNA chaperone system utilizes chemical energy of ATP hydrolysis to
repeatedly bind and release misfolded and folded RNAs, resulting in substantial
increase of yield of the native state. The theory outlined here shows, in
accord with experiments, that in the steady state the native state does not
form with unit probability.


title: A note on causality in Banach spaces

abstract:
  In this note we provide examples that show that a common notion of causality
for linear operators on Banach spaces does not carry over to the closure of the
respective operators. We provide an alternative definition for causality, which
is equivalent to the usual definition for closed linear operators but does
carry over to the closure.


title: TBA type equations and tropical curves

abstract:
  We revisit the wall-crossing behaviour of solutions to the Thermodynamic
Bethe Ansatz type equations arising in a class of three-dimensional field
theories, expressed as sums of "instanton corrections". We explain how to
attach to an instanton correction at a critical value a set of (combinatorial
types of) tropical curves in R^2 of fixed degree, which determines its jump to
leading order. We show that a weighted sum over all such curves is in fact a
tropical count. This goes through to the q-deformed setting. Our construction
can be regarded as a formal mirror symmetric statement in the framework
proposed by Gaiotto, Moore and Neitzke.


title: On the characterization of Galois extensions

abstract:
  We present a shortcut to the familiar characterizations of finite Galois
extensions, based on an idea from an earlier Monthly note by Sonn and
Zassenhaus.


title: MnSb2O6: A polar magnet with a chiral crystal structure

abstract:
  Structural and magnetic chiralities are found to coexist in a small group of
materials in which they produce intriguing phenomenologies such as the recently
discovered skyrmion phases. Here, we describe a previously unknown
manifestation of this interplay in MnSb2O6, a trigonal oxide with a chiral
crystal structure. Unlike all other known cases, the MnSb2O6 magnetic structure
is based on co-rotating cycloids rather than helices. The coupling to the
structural chirality is provided by a magnetic axial vector, related to the
so-called vector chirality. We show that this unique arrangement is the
magnetic ground state of the symmetric-exchange Hamiltonian, based on ab-initio
theoretical calculations of the Heisenberg exchange interactions, and is
stabilised by out-of-plane anisotropy. MnSb2O6 is predicted to be multiferroic
with a unique ferroelectric switching mechanism.


title: Two-View Matching with View Synthesis Revisited

abstract:
  Wide-baseline matching focussing on problems with extreme viewpoint change is
considered. We introduce the use of view synthesis with affine-covariant
detectors to solve such problems and show that matching with the Hessian-Affine
or MSER detectors outperforms the state-of-the-art ASIFT.
  To minimise the loss of speed caused by view synthesis, we propose the
Matching On Demand with view Synthesis algorithm (MODS) that uses progressively
more synthesized images and more (time-consuming) detectors until reliable
estimation of geometry is possible. We show experimentally that the MODS
algorithm solves problems beyond the state-of-the-art and yet is comparable in
speed to standard wide-baseline matchers on simpler problems.
  Minor contributions include an improved method for tentative correspondence
selection, applicable both with and without view synthesis and a view synthesis
setup greatly improving MSER robustness to blur and scale change that increase
its running time by 10% only.


title: From Text to Bank Interrelation Maps

abstract:
  In the wake of the ongoing global financial crisis, interdependencies among
banks have come into focus in trying to assess systemic risk. To date, such
analysis has largely been based on numerical data. By contrast, this study
attempts to gain further insight into bank interconnections by tapping into
financial discussion. Co-mentions of bank names are turned into a network,
which can be visualized and analyzed quantitatively, in order to illustrate
characteristics of individual banks and the network as a whole. The approach
allows for the study of temporal dynamics of the network, to highlight changing
patterns of discussion that reflect real-world events, the current financial
crisis in particular. For instance, it depicts how connections from distressed
banks to other banks and supervisory authorities have emerged and faded over
time, as well as how global shifts in network structure coincide with severe
crisis episodes. The usage of textual data holds an additional advantage in the
possibility of gaining a more qualitative understanding of an observed
interrelation, through its context. We illustrate our approach using a case
study on Finnish banks and financial institutions. The data set comprises 3.9M
posts from online, financial and business-related discussion, during the years
2004 to 2012. Future research includes analyzing European news articles with a
broader perspective, and a focus on improving semantic description of
relations.


title: Computing Tree-depth Faster Than $2^{n}$

abstract:
  A connected graph has tree-depth at most $k$ if it is a subgraph of the
closure of a rooted tree whose height is at most $k$. We give an algorithm
which for a given $n$-vertex graph $G$, in time $\mathcal{O}(1.9602^n)$
computes the tree-depth of $G$. Our algorithm is based on combinatorial results
revealing the structure of minimal rooted trees whose closures contain $G$.


title:
Path-wise versus kinetic modeling for equilibrating non-Langevin
  jump-type processes

abstract:
  We discuss two independent methods of solution of a master equation whose
biased jump transition rates account for long jumps of L\'{e}vy-stable type and
nonetheless admit a Boltzmannian (thermal) equilibrium to arise in the large
time asymptotics of a probability density function $\rho (x,t)$. Our main goal
is to demonstrate a compatibility of a {\it direct} solution method (an
explicit, albeit numerically assisted, integration of the master equation) with
an {\it indirect} path-wise procedure, recently proposed in [Physica {\bf A
392}, 3485, (2013)] as a valid tool for a dynamical analysis of non-Langevin
jump-type processes. The path-wise method heavily relies on an accumulation of
large sample path data, that are generated by means of a properly tailored
Gillespie's algorithm. Their statistical analysis in turn allows to infer the
dynamics of $\rho (x,t)$. However, no consistency check has been completed so
far to demonstrate that both methods are fully compatible and indeed provide a
solution of the same dynamical problem. Presently we remove this gap, with a
focus on potential deficiencies (various cutoffs, including those upon the jump
size) of approximations involved in solution protocols.


title: Poisson-Gerstenhaber brackets in representation algebras

abstract:
  We introduce cyclic bilinear forms on coalgebras and use them to generalize
Van den Bergh's Poisson brackets in representation algebras.


title:
Cluster coloring of the Self-Organizing Map: An information
  visualization perspective

abstract:
  This paper takes an information visualization perspective to visual
representations in the general SOM paradigm. This involves viewing SOM-based
visualizations through the eyes of Bertin's and Tufte's theories on data
graphics. The regular grid shape of the Self-Organizing Map (SOM), while being
a virtue for linking visualizations to it, restricts representation of cluster
structures. From the viewpoint of information visualization, this paper
provides a general, yet simple, solution to projection-based coloring of the
SOM that reveals structures. First, the proposed color space is easy to
construct and customize to the purpose of use, while aiming at being
perceptually correct and informative through two separable dimensions. Second,
the coloring method is not dependent on any specific method of projection, but
is rather modular to fit any objective function suitable for the task at hand.
The cluster coloring is illustrated on two datasets: the iris data, and welfare
and poverty indicators.


title: Nonuniversality of indirect CP asymmetries in $D \to \pi\pi, KK$ decays

abstract:
  We point out that, if the direct CP asymmetries in the $D \to \pi^+ \pi^-$
and $D \to K^+ K^-$ decays are unequal, the indirect CP asymmetries as measured
in these modes are necessarily unequal. This nonuniversality of indirect CP
asymmetries can be significant with the right amount of new physics
contributions, a scenario that may be fine-tuned, but is still viable. A
model-independent fit to the current data allows different indirect CP
asymmetries in the above two decays. This could even be contributing to the
apparent tension between the difference CP asymmetries $\Delta A_{\rm CP}$
measured through the pion-tagged and muon-tagged data samples at the LHCb. This
also implies that the measurements of $A_\Gamma$ and $y_{\rm CP}$ in the $\pi^+
\pi^-$ and $K^+ K^-$ decay modes can be different, and averaging over these two
modes should be avoided. In any case, the complete analysis of CP violation
measurements in the $D$ meson sector needs to take into account the possibility
of different indirect CP asymmetries in the $\pi^+\pi^-$ and $K^+ K^-$
channels.


title:
Bayesian methods for low-rank matrix estimation: short survey and
  theoretical study

abstract:
  The problem of low-rank matrix estimation recently received a lot of
attention due to challenging applications. A lot of work has been done on
rank-penalized methods and convex relaxation, both on the theoretical and
applied sides. However, only a few papers considered Bayesian estimation. In
this paper, we review the different type of priors considered on matrices to
favour low-rank. We also prove that the obtained Bayesian estimators, under
suitable assumptions, enjoys the same optimality properties as the ones based
on penalization.


title:
On the total mass of closed universes with a positive cosmological
  constant

abstract:
  The recently suggested notion of total mass density for closed universes is
extended to closed universes with a positive cosmological constant. Assuming
that the matter fields satisfy the dominant energy condition, it is shown that
the cosmological constant provides a sharp lower bound for the total mass
density, and that the total mass density takes this as its minimum value if and
only if the spacetime is locally isometric with the de Sitter spacetime. This
notion of total mass density is extensible to non-compact three-spaces of
homogeneity of Bianchi class A cosmological spacetimes.


title:
Electromagnetic structure of the nucleon and the Roper resonance in a
  light-front quark approach

abstract:
  A relativistic light-front quark model is used to describe both the elastic
nucleon and nucleon-Roper transition form factors in a large Q2 range, up to 35
GeV2 for the elastic and up to 12 GeV2 for the resonance case. Relativistic
three-quark configurations satisfying the Pauli exclusion principle on the
light-front are used for the derivation of the current matrix elements. The
Roper resonance is considered as a mixed state of a three-quark core
configuration and a molecular N+sigma hadron component. Based on this ansatz we
obtain a realistic description of both processes, elastic and inelastic, and
show that existing experimental data are indicative of a composite structure of
the Roper resonance.


title:
Octahedron configuration for a displacement noise-cancelling
  gravitational wave detector in space

abstract:
  We study for the first time a three-dimensional octahedron constellation for
a space-based gravitational wave detector, which we call the Octahedral
Gravitational Observatory (OGO). With six spacecraft the constellation is able
to remove laser frequency noise and acceleration disturbances from the
gravitational wave signal without needing LISA-like drag-free control, thereby
simplifying the payloads and placing less stringent demands on the thrusters.
We generalize LISA's time-delay interferometry to displacement-noise free
interferometry (DFI) by deriving a set of generators for those combinations of
the data streams that cancel laser and acceleration noise. However, the
three-dimensional configuration makes orbit selection complicated. So far, only
a halo orbit near the Lagrangian point L1 has been found to be stable enough,
and this allows only short arms up to 1400 km. We derive the sensitivity curve
of OGO with this arm length, resulting in a peak sensitivity of about
$2\times10^{-23}\,\mathrm{Hz}^{-1/2}$ near 100 Hz. We compare this version of
OGO to the present generation of ground-based detectors and to some future
detectors. We also investigate the scientific potentials of such a detector,
which include observing gravitational waves from compact binary coalescences,
the stochastic background and pulsars as well as the possibility to test
alternative theories of gravity. We find a mediocre performance level for this
short-arm-length detector, between those of initial and advanced ground-based
detectors. Thus, actually building a space-based detector of this specific
configuration does not seem very efficient. However, when alternative orbits
that allow for longer detector arms can be found, a detector with much improved
science output could be constructed using the octahedron configuration and DFI
solutions demonstrated in this paper. (abridged)


title: Efficiency at maximum power of a chemical engine

abstract:
  A cyclically operating chemical engine is considered that converts chemical
energy into mechanical work. The working fluid is a gas of finite-sized
spherical particles interacting through elastic hard collisions. For a generic
transport law for particle uptake and release, the efficiency at maximum power
$\eta$ takes the form 1/2+c\Delta \mu + O(\Delta \mu^2), with 1/2 a universal
constant and $\Delta \mu$ the chemical potential difference between the
particle reservoirs. The linear coefficient c is zero for engines featuring a
so-called left/right symmetry or particle fluxes that are antisymmetric in the
applied chemical potential difference. Remarkably, the leading constant in
$\eta$ is non-universal with respect to an exceptional modification of the
transport law. For a nonlinear transport model we obtain \eta = 1/(\theta +1),
with \theta >0 the power of $\Delta \mu$ in the transport equation


title:
Integer matrices that are not copositive have certificates of less than
  quadratic complexity

abstract:
  A real symmetric n times n matrix is called copositive if the corresponding
quadratic form is non-negative on the closed first orthant. If the matrix fails
to be copositive there exists some non-negative certificate for which the
quadratic form is negative. Due to the scaling property, we can find such
certificates in every neighborhood of the origin but their properties depend on
the matrix of course and are hard to describe. If it is an integer matrix
however, we are guaranteed certificates of a complexity that is at most a
constant times the binary encoding length of the matrix raised to the power
3/2.


title: Oscillons and oscillating kinks in the Abelian-Higgs model

abstract:
  We study the classical dynamics of the Abelian Higgs model employing an
asymptotic multiscale expansion method, which uses the ratio of the Higgs to
the gauge field amplitudes as a small parameter. We derive an effective
nonlinear Schrodinger equation for the gauge field, and a linear equation for
the scalar field containing the gauge field as a nonlinear source. This
equation is used to predict the existence of oscillons and oscillating kinks
for certain regimes of the ratio of the Higgs to the gauge field masses.
Results of direct numerical simulations are found to be in very good agreement
with the analytical findings, and show that the oscillons are robust, while
kinks are unstable. It is also demonstrated that oscillons emerge spontaneously
as a result of the onset of the modulational instability of plane wave
solutions of the model. Connections of the results with the phenomenology of
superconductors is discussed.


title:
Generic base algebras and universal comodule algebras for some
  finite-dimensional Hopf algebras

abstract:
  After recalling the definitions and the properties of the generic base
algebra and of the universal comodule algebra attached to a Hopf algebra by
Aljadeff and the second-named author, we determine these algebras for the Taft
algebras, the Hopf algebras E(n), and certain monomial Hopf algebras.


title:
Majorana Fermions in Periodically Driven Semiconductor-Superconductor
  Heterostructure

abstract:
  We propose a new approach to create Majorana fermions at the edge of a
periodically driven semiconductor-superconductor Heterostructure. We calculate
the quasi-energy spectrum of the periodically driven Heterostructure by using
the Floquet's theory. When the interaction between different Brillouin zones of
quasi-energy is neglected, one Majorana fermion can be created at each edge of
the Heterostructure when the ratio of driven amplitude and driven frequency is
larger than a minimum. Furthermore, when the interaction between the nearest
Brillouin zones of quasi-energy is considered, we restrict the condition of
creating Majorana fermions above with a lower limit of the driven frequency. We
also discuss the experimental protocol of creating Majorana fermions in the
periodically driven Heterostructure.


title:
Eigenvalue structure of a Bose-Einstein condensate in a PT-symmetric
  double well

abstract:
  We study a Bose-Einstein condensate in a PT-symmetric double-well potential
where particles are coherently injected in one well and removed from the other
well. In mean-field approximation the condensate is described by the
Gross-Pitaevskii equation thus falling into the category of nonlinear
non-Hermitian quantum systems. After extending the concept of PT symmetry to
such systems, we apply an analytic continuation to the Gross-Pitaevskii
equation from complex to bicomplex numbers and show a thorough numerical
investigation of the four-dimensional bicomplex eigenvalue spectrum. The
continuation introduces additional symmetries to the system which are confirmed
by the numerical calculations and furthermore allows us to analyze the
bifurcation scenarios and exceptional points of the system. We present a linear
matrix model and show the excellent agreement with our numerical results. The
matrix model includes both exceptional points found in the double-well
potential, namely an EP2 at the tangent bifurcation and an EP3 at the pitchfork
bifurcation. When the two bifurcation points coincide the matrix model
possesses four degenerate eigenvectors. Close to that point we observe the
characteristic features of four interacting modes in both the matrix model and
the numerical calculations, which provides clear evidence for the existence of
an EP4.


title:
Influencing the conductance in biphenyl-like molecular junctions with
  THz radiation

abstract:
  We investigate the torsional vibrations in biphenyl-like molecular junctions
and transport properties in the presence of an external THz field. Ab-initio
calculations including external electric fields show that the torsional angle
{\phi} of a thiolated biphenyl junction exhibits virtually no response.
However, if functional groups are added to the molecule, creating a dipole
moment in each of the rings, an external field becomes more effective for
changing {\phi}. A model based on the cos2{\phi} dependence of the current is
proposed for the biphenyl-like molecular junctions in presence of an external
THz field including 2,2'-bipyridine, 3,3'-bipyridine and 2,2',4,4'-
tetramethyl-3,3'-bipyridine. The current through these molecules is shown to
change if the THz frequency gets in resonance to the torsional vibration mode.


title: Fast Scramblers And Ultrametric Black Hole Horizons

abstract:
  We propose that fast scrambling on finite-entropy stretched horizons can be
modeled by a diffusion process on an effective ultrametric geometry. A
scrambling time scaling logarithmically with the entropy is obtained when the
elementary transition rates saturate causality bounds on the stretched horizon.
The so-defined ultrametric diffusion becomes unstable in the infinite-entropy
limit. A formally regularized version can be shown to follow a particular case
of the Kohlrausch law.


title:
Classifying and Visualizing Motion Capture Sequences using Deep Neural
  Networks

abstract:
  The gesture recognition using motion capture data and depth sensors has
recently drawn more attention in vision recognition. Currently most systems
only classify dataset with a couple of dozens different actions. Moreover,
feature extraction from the data is often computational complex. In this paper,
we propose a novel system to recognize the actions from skeleton data with
simple, but effective, features using deep neural networks. Features are
extracted for each frame based on the relative positions of joints (PO),
temporal differences (TD), and normalized trajectories of motion (NT). Given
these features a hybrid multi-layer perceptron is trained, which simultaneously
classifies and reconstructs input data. We use deep autoencoder to visualize
learnt features, and the experiments show that deep neural networks can capture
more discriminative information than, for instance, principal component
analysis can. We test our system on a public database with 65 classes and more
than 2,000 motion sequences. We obtain an accuracy above 95% which is, to our
knowledge, the state of the art result for such a large dataset.


title:
Roughening Methods to Prevent Sample Impoverishment in the Particle PHD
  Filter

abstract:
  Mahler's PHD (Probability Hypothesis Density) filter and its particle
implementation (as called the particle PHD filter) have gained popularity to
solve general MTT (Multi-target Tracking) problems. However, the resampling
procedure used in the particle PHD filter can cause sample impoverishment. To
rejuvenate the diversity of particles, two easy-to-implement roughening
approaches are presented to enhance the particle PHD filter. One termed as
"separate-roughening" is inspired by Gordon's roughening procedure that is
applied on the resampled particles. Another termed as "direct-roughening" is
implemented by increasing the simulation noise of the state propagation of
particles. Four proposals are presented to customize the roughening approach.
Simulations are presented showing that the roughening approach can benefit the
particle PHD filter, especially when the sample size is small.


title: Dark matter and Wigner's third positive-energy representation class

abstract:
  The almost 7 decades lasting futile attempts to understand the possible
physical content of the third Wigner representation class (the infinite spin
class) came to a partial solution with the 2006 discovery of existence of
string-localized spacetime covariantizations . This has led to a still ongoing
vast generalization of renormalizability to fields with arbitrary high spin and
a better understanding of the origin of partial invisibility as observed in the
confinement of gluons and quarks. The present note explains the total
(non-gravitational) invisibility of fields associated to the third Wigner
representation class. The last section presents a critical look at the
possibility that third class Wigner matter may play a role in dark matter
formation.


title: Fast branching algorithm for Cluster Vertex Deletion

abstract:
  In the family of clustering problems, we are given a set of objects (vertices
of the graph), together with some observed pairwise similarities (edges). The
goal is to identify clusters of similar objects by slightly modifying the graph
to obtain a cluster graph (disjoint union of cliques). Hueffner et al. [Theory
Comput. Syst. 2010] initiated the parameterized study of Cluster Vertex
Deletion, where the allowed modification is vertex deletion, and presented an
elegant O(2^k * k^9 + n * m)-time fixed-parameter algorithm, parameterized by
the solution size. In our work, we pick up this line of research and present an
O(1.9102^k * (n + m))-time branching algorithm.


title:
Atomic ionization by twisted photons: Angular distribution of emitted
  electrons

abstract:
  We investigate the angular distribution of electrons that are emitted in the
ionization of hydrogen-like ions by twisted photons. Analysis is performed
based on the first-order perturbation theory and the non-relativistic
Schr\"odinger equation. Special attention is paid to the dependence of the
electron emission pattern on the impact parameter b of the ion with respect to
the centre of the twisted wave front. In order to explore such a dependence,
detailed calculations were carried out for the photoionization of the 1s ground
and 2 py excited states of neutral hydrogen atoms. Based on these calculations,
we argue that for relatively small impact parameters the electron angular
distributions may be strongly affected by altering the position of the atom
within the wave front. In contrast, if the atom is placed far from the front
centre, the emission pattern of the electrons is independent on the impact
parameter b and resembles that observed in the photoionization by plane wave
photons.


title:
Chandra View of the Ultra-Steep Spectrum Radio Source in Abell 2443:
  Merger Shock-Induced Compression of Fossil Radio Plasma?

abstract:
  We present a new Chandra X-ray observation of the intracluster medium in the
galaxy cluster Abell 2443, hosting an ultra-steep spectrum radio source. The
data reveal that the intracluster medium is highly disturbed. The thermal gas
in the core is elongated along a northwest to southeast axis and there is a
cool tail to the north. We also detect two X-ray surface brightness edges near
the cluster core. The edges appear to be consistent with an inner cold front to
the northeast of the core and an outer shock front to the southeast of the
core. The southeastern edge is coincident with the location of the radio relic
as expected for shock (re)acceleration or adiabatic compression of fossil
relativistic electrons.


title:
On free-group algorithms that sandwich a subgroup between free-product
  factors

abstract:
  Let $F$ be a finite-rank free group and $H$ be a finite-rank subgroup of $F$.
We discuss proofs of two algorithms that sandwich $H$ between an upper-layer
free-product factor of $F$ that contains $H$ and a lower-layer free-product
factor of $F$ that is contained in $H$.
  Richard Stong showed that the unique smallest-possible upper layer, denoted
$\operatorname{Cl}(H)$, is visible in the output of the polynomial-time
cut-vertex algorithm of J. H. C. Whitehead. Stong's proof used bi-infinite
paths in a Cayley tree and sub-surfaces of a three-manifold. We give a variant
of his proof that uses edge-cuts of the Cayley tree induced by edge-cuts of a
Bass-Serre tree.
  A. Clifford and R. Z. Goldstein gave an exponential-time algorithm that
determines whether or not the trivial subgroup is the only possible lower
layer. Their proof used Whitehead's three-manifold techniques. We give a
variant of their proof that uses Whitehead's cut-vertex results, and thereby
obtain a somewhat simpler algorithm that yields a lower layer of
maximum-possible rank.


title: Non-perturbative Renormalization for Improved Staggered Bilinears

abstract:
  We apply non-perturbative renormalization to bilinears composed of improved
staggered fermions. We explain how to generalize the method to staggered
fermions in a way which is consistent with the lattice symmetries, and
introduce a new type of lattice bilinear which transforms covariantly and
avoids mixing. We derive the consequences of lattice symmetries for the
propagator and vertices. We implement the method numerically for
hypercubic-smeared (HYP) and asqtad valence fermion actions, using lattices
with asqtad sea quarks generated by the MILC collaboration. We compare the
non-perturbative results so obtained to those from perturbation theory, using
both scale-independent ratios of bilinears (of which we calculate 26), and the
scale-dependent bilinears themselves. Overall, we find that one-loop
perturbation theory provides a successful description of the results for
HYP-fermions if we allow for a truncation error of roughly the size of the
square of the one-loop term (for ratios) or of size O(1) \times \alpha^2 (for
the bilinears themselves). Perturbation theory is, however, less successful at
describing the non-perturbative asqtad results.


title: Chaining Test Cases for Reactive System Testing (extended version)

abstract:
  Testing of synchronous reactive systems is challenging because long input
sequences are often needed to drive them into a state at which a desired
feature can be tested. This is particularly problematic in on-target testing,
where a system is tested in its real-life application environment and the time
required for resetting is high. This paper presents an approach to discovering
a test case chain---a single software execution that covers a group of test
goals and minimises overall test execution time. Our technique targets the
scenario in which test goals for the requirements are given as safety
properties. We give conditions for the existence and minimality of a single
test case chain and minimise the number of test chains if a single test chain
is infeasible. We report experimental results with a prototype tool for C code
generated from Simulink models and compare it to state-of-the-art test suite
generators.


title:
The Near Infrared Ca II Triplet as Metallicity Indicator: II Extension
  to extremely metal-poor metallicity regimes

abstract:
  We extend our previous calibration of the infrared Ca II triplet as
metallicity indicator to the metal-poor regime by including observations of 55
field stars with [Fe/H] down to -4.0 dex. While we previously solved the
saturation at high-metallicity using a combination of a Lorentzian plus a
Gaussian to reproduce the line profiles, in this paper we address the
non-linearity at low-metallicity following the suggestion of Starkenburg et al
2010 of adding two non-linear terms to the relation among the [Fe/H],
luminosity, and strength of the Calcium triplet lines. Our calibration thus
extends from -4.0 to +0.5 in metallicity and is presented using four different
luminosity indicators: V-V_{HB}, M_V, M_I, and M_K. The calibration obtained in
this paper results in a tight correlation between [Fe/H] abundances measured
from high resolution spectra and [Fe/H] values derived from the CaT, over the
whole metallicity range covered.


title: The Rise and Fall of Semantic Rule Updates Based on SE-Models

abstract:
  Logic programs under the stable model semantics, or answer-set programs,
provide an expressive rule-based knowledge representation framework, featuring
a formal, declarative and well-understood semantics. However, handling the
evolution of rule bases is still a largely open problem. The AGM framework for
belief change was shown to give inappropriate results when directly applied to
logic programs under a non-monotonic semantics such as the stable models. The
approaches to address this issue, developed so far, proposed update semantics
based on manipulating the syntactic structure of programs and rules.
  More recently, AGM revision has been successfully applied to a significantly
more expressive semantic characterisation of logic programs based on SE-models.
This is an important step, as it changes the focus from the evolution of a
syntactic representation of a rule base to the evolution of its semantic
content.
  In this paper, we borrow results from the area of belief update to tackle the
problem of updating (instead of revising) answer-set programs. We prove a
representation theorem which makes it possible to constructively define any
operator satisfying a set of postulates derived from Katsuno and Mendelzon's
postulates for belief update. We define a specific operator based on this
theorem, examine its computational complexity and compare the behaviour of this
operator with syntactic rule update semantics from the literature. Perhaps
surprisingly, we uncover a serious drawback of all rule update operators based
on Katsuno and Mendelzon's approach to update and on SE-models.


title: On the Statistical Analysis of X-ray Polarization Measurements

abstract:
  In many polarimetry applications, including observations in the X-ray band,
the measurement of a polarization signal can be reduced to the detection and
quantification of a deviation from uniformity of a distribution of measured
angles. We explore the statistics of such polarization measurements using Monte
Carlo simulations and chi-squared fitting methods. We compare our results to
those derived using the traditional probability density used to characterize
polarization measurements and quantify how they deviate as the intrinsic
modulation amplitude grows. We derive relations for the number of counts
required to reach a given detection level (parameterized by beta, the "number
of sigma's" of the measurement) appropriate for measuring the modulation
amplitude by itself (single interesting parameter case) or jointly with the
position angle (two interesting parameters case). We show that for the former
case when the intrinsic amplitude is equal to the well known minimum detectable
polarization (MDP) it is, on average, detected at the 3-sigma level. For the
latter case, when one requires a joint measurement at the same confidence
level, then more counts are needed than that required to achieve the MDP level.
This additional factor is amplitude-dependent, but is approximately 2.2 for
intrinsic amplitudes less than about 20%. It decreases slowly with amplitude
and is 1.8 when the amplitude is 50%. We find that the position angle
uncertainty at 1-sigma confidence is well described by the relation 28.5 (deg)
/ beta.


title:
Modified theories of gravity with nonminimal coupling and orbital
  particle dynamics

abstract:
  We consider a non-rotating, massive test particle acted upon by a
"pressure"-type, non-geodesic acceleration arising from a certain general class
of gravitational theories with nonminimal coupling between the matter and the
metric. The resulting orbital perturbations for a two-body system are
investigated both analytically and numerically. Among the other long-term
effects, a secular increase of the two-body relative distance occurs. In
principle, it may yield a physical mechanism for the steady recession of the
Earth from the Sun recently proposed to explain the Faint Young Sun Paradox in
the Archean eon. At present, the theorists have not yet derived explicit
expressions for some of the key parameters of the model, such as the integrated
"charge" $\xi$, depending on the matter distribution of the system, and the
4-vector $K^{\mu}=\{K^0,\boldsymbol{K}\}$ connected with the nonminimal
function $F$. Thus, we phenomenologically treat them as free parameters, and
preliminarily infer some indications on their admissible values according to
the most recent Solar System's planetary ephemerides. From the latest
determinations of the corrections $\Delta\dot\varpi$ to the standard perihelion
precessions, estimated by the astronomers who produced the EPM2011 ephemerides
without modeling the theory considered here, we preliminarily obtain $|\xi
K|\lesssim 0.1$ kg s$^{-1}$ for Mars. From guesses on what could be the current
bounds on the secular rates of change of the planetary semimajor axes, we get
$|\xi K^0|\lesssim 1249$ kg s$^{-1}$ for Mars. More effective constraints could
be posed by reprocessing the same planetary data sets with dedicated dynamical
models including the effects studied here, and explicitly estimating the
associated parameters. COBE and GP-B terrestrial satellites yield $|\xi
K|\lesssim 2\times 10^{-4}$ kg s$^{-1}$ and $|\xi K_0|\lesssim 2\times
10^{-10}$ kg s$^{-1}$.


title:
Magnetic excitations in the spin-1/2 triangular-lattice antiferromagnet
  Cs$_2$CuBr$_4$

abstract:
  We report on high-field electron spin resonance (ESR) studies of magnetic
excitations in the spin-1/2 triangular-lattice antiferromagnet Cs$_2$CuBr$_4$.
Frequency-field diagrams of ESR excitations are measured for different
orientations of magnetic fields up to 25 T. We show that the substantial
zero-field energy gap, $\Delta\approx9.5$ K, observed in the low-temperature
excitation spectrum of Cs$_2$CuBr$_4$ [Zvyagin $et~al.$, Phys. Rev. Lett. 112,
077206 (2014)], is present well above $T_N$. Noticeably, the transition into
the long-range magnetically ordered phase does not significantly affect the
size of the gap, suggesting that even below $T_N$ the high-energy spin dynamics
in Cs$_2$CuBr$_4$ is determined by short-range-order spin correlations. The
experimental data are compared with results of model spin-wave-theory
calculations for spin-1/2 triangle-lattice antiferromagnet.


title: The SP theory of intelligence: an overview

abstract:
  This article is an overview of the "SP theory of intelligence". The theory
aims to simplify and integrate concepts across artificial intelligence,
mainstream computing and human perception and cognition, with information
compression as a unifying theme. It is conceived as a brain-like system that
receives 'New' information and stores some or all of it in compressed form as
'Old' information. It is realised in the form of a computer model -- a first
version of the SP machine. The concept of "multiple alignment" is a powerful
central idea. Using heuristic techniques, the system builds multiple alignments
that are 'good' in terms of information compression. For each multiple
alignment, probabilities may be calculated. These provide the basis for
calculating the probabilities of inferences. The system learns new structures
from partial matches between patterns. Using heuristic techniques, the system
searches for sets of structures that are 'good' in terms of information
compression. These are normally ones that people judge to be 'natural', in
accordance with the 'DONSVIC' principle -- the discovery of natural structures
via information compression. The SP theory may be applied in several areas
including 'computing', aspects of mathematics and logic, representation of
knowledge, natural language processing, pattern recognition, several kinds of
reasoning, information storage and retrieval, planning and problem solving,
information compression, neuroscience, and human perception and cognition.
Examples include the parsing and production of language including discontinuous
dependencies in syntax, pattern recognition at multiple levels of abstraction
and its integration with part-whole relations, nonmonotonic reasoning and
reasoning with default values, reasoning in Bayesian networks including
'explaining away', causal diagnosis, and the solving of a geometric analogy
problem.


title:
Cavity-mediated near-critical dissipative dynamics of a driven
  condensate

abstract:
  We investigate the near-critical dynamics of atomic density fluctuations in
the non-equilibrium self-organization transition of an optically driven quantum
gas coupled to a single mode of a cavity. In this system cavity-mediated
long-range interactions between atoms, tunable by the drive strength, lead to
softening of an excitation mode recently observed in experiments. This
phenomenon has previously been studied within a two-mode approximation for the
collective motional degrees of freedom of the atomic condensate which results
in an effective open-system Dicke model. Here, including the full spectrum of
atomic modes we find a finite lifetime for a roton-like mode in the Bogoliubov
excitation spectrum that is strongly pump-dependent. The corresponding decay
rate and critical exponents for the phase-transition are calculated explaining
the non-monotonic pump-dependent atomic damping rate observed in recent
experiments. We compute the near-critical behavior of the intra-cavity field
fluctuations, that has been previously shown to be enhanced with respect to the
equilibrium Dicke model in a two-mode approximation. We highlight the role of
the finite size of the system in the suppression of it below the expectations
of the open Dicke model.


title: Big data and the SP theory of intelligence

abstract:
  This article is about how the "SP theory of intelligence" and its realisation
in the "SP machine" may, with advantage, be applied to the management and
analysis of big data. The SP system -- introduced in the article and fully
described elsewhere -- may help to overcome the problem of variety in big data:
it has potential as "a universal framework for the representation and
processing of diverse kinds of knowledge" (UFK), helping to reduce the
diversity of formalisms and formats for knowledge and the different ways in
which they are processed. It has strengths in the unsupervised learning or
discovery of structure in data, in pattern recognition, in the parsing and
production of natural language, in several kinds of reasoning, and more. It
lends itself to the analysis of streaming data, helping to overcome the problem
of velocity in big data. Central in the workings of the system is lossless
compression of information: making big data smaller and reducing problems of
storage and management. There is potential for substantial economies in the
transmission of data, for big cuts in the use of energy in computing, for
faster processing, and for smaller and lighter computers. The system provides a
handle on the problem of veracity in big data, with potential to assist in the
management of errors and uncertainties in data. It lends itself to the
visualisation of knowledge structures and inferential processes. A
high-parallel, open-source version of the SP machine would provide a means for
researchers everywhere to explore what can be done with the system and to
create new versions of it.


title: Twisted supersymmetries in lattice ${\cal N}=4$ super Yang-Mills theory

abstract:
  Recently it has been shown how a topologically twisted version of ${\cal
N}=4$ super Yang-Mills may be discretized in such a way as to preserve one
scalar supersymmetry at nonzero lattice spacing. The remaining fifteen
supersymmetries are broken by terms of ${\cal O}(a)$ where $a$ is the lattice
spacing. One would like to know whether these remaining supersymmetries are
regained in the continuum limit $a \to 0$ and, if not, how much tuning of the
couplings in the lattice action is required. In this paper we derive the form
of these additional twisted supersymmetries by combining a set of discrete
R-symmetries of the continuum theory with the action of the scalar
supersymmetry. We then argue that restoration of rotational symmetry in the
continuum limit of the lattice theory likely implies restoration of R-symmetry
and hence should lead to an automatic enhancement to the full ${\cal N}=4$
supersymmetry without further fine-tuning.


title: Generalized quiver Hecke algebras

abstract:
  We generalize the geometric construction of quiver Hecke algebras from
Varagnolo and Vasserot to a setup with arbitrary connected reductive groups.
This corresponds to replacing quiver representations by generalized quiver
representations introduced by Derksen and Weyman. The class of algebras which
we construct contains (affine) nil Hecke algebras, skew group rings of Weyl
groups with polynomial rings and quiver Hecke algebras. We describe an explicit
faithful representation in a polynomial ring and we calculate the generators
and relations for these algebras.


title:
The gravity dual of supersymmetric gauge theories on a two-parameter
  deformed three-sphere

abstract:
  We present rigid supersymmetric backgrounds for three-dimensional N=2
supersymmetric gauge theories, comprising a two-parameter U(1)xU(1)-invariant
deformed three-sphere, and their gravity duals. These are described by
supersymmetric solutions of four-dimensional N=2 gauged supergravity with a
self-dual metric on the ball and different instantons for the graviphoton
field. We find two types of solutions, distinguished by their holographic free
energies. In one type the holographic free energy is constant, whereas in
another type it depends in a simple way on the parameters and is generically
complex. This leads to a conjecture for the localized partition function of a
class of N=2 supersymmetric gauge theories on these backgrounds.


title: Tailoring the ground state of the ferrimagnet La2Ni(Ni1/3Sb2/3)O6

abstract:
  We report on the magnetic and structural properties of La2Ni(Ni1/3Sb2/3)O6 in
polycrystal, single crystal and thin film samples. We found that this material
is a ferrimagnet (Tc ~ 100 K) which possesses a very distinctive and uncommon
feature in its virgin curve of the hysteresis loops. We observe that bellow 20
K it lies outside the hysteresis cycle, and this feature was found to be an
indication of a microscopically irreversible process possibly involving the
interplay of competing antiferromagnetic interactions that hinder the initial
movement of domain walls. This initial magnetic state is overcome by applying a
temperature dependent characteristic field. Above this field, an isothermal
magnetic demagnetization of the samples yield a ground state different from the
initial thermally demagnetized one.


title: On-line PCA with Optimal Regrets

abstract:
  We carefully investigate the on-line version of PCA, where in each trial a
learning algorithm plays a k-dimensional subspace, and suffers the compression
loss on the next instance when projected into the chosen subspace. In this
setting, we analyze two popular on-line algorithms, Gradient Descent (GD) and
Exponentiated Gradient (EG). We show that both algorithms are essentially
optimal in the worst-case. This comes as a surprise, since EG is known to
perform sub-optimally when the instances are sparse. This different behavior of
EG for PCA is mainly related to the non-negativity of the loss in this case,
which makes the PCA setting qualitatively different from other settings studied
in the literature. Furthermore, we show that when considering regret bounds as
function of a loss budget, EG remains optimal and strictly outperforms GD.
Next, we study the extension of the PCA setting, in which the Nature is allowed
to play with dense instances, which are positive matrices with bounded largest
eigenvalue. Again we can show that EG is optimal and strictly better than GD in
this setting.


title:
Improving the efficiency of the LDPC code-based McEliece cryptosystem
  through irregular codes

abstract:
  We consider the framework of the McEliece cryptosystem based on LDPC codes,
which is a promising post-quantum alternative to classical public key
cryptosystems. The use of LDPC codes in this context allows to achieve good
security levels with very compact keys, which is an important advantage over
the classical McEliece cryptosystem based on Goppa codes. However, only regular
LDPC codes have been considered up to now, while some further improvement can
be achieved by using irregular LDPC codes, which are known to achieve better
error correction performance than regular LDPC codes. This is shown in this
paper, for the first time at our knowledge. The possible use of irregular
transformation matrices is also investigated, which further increases the
efficiency of the system, especially in regard to the public key size.


title: The Bochner Formula via Volume Variations

abstract:
  In this short paper, we re-derive the Bochner formula for the Laplacian by
considering local variations of volume.
  The derivation is rooted in the fact that the Laplacian of a function
measures the volume variation along the flow of the gradient vector of the
function. Possible extensions of this approach/technique are also discussed.
While the value of this approach may be limited in terms of research, we think
it definitely has pedagogical value.


title: Extraordinary Gauge Mediation at Finite Temperature

abstract:
  We investigate minimally completed models of extraordinary gauge mediation,
which are examples of direct gauge mediation, at finite temperature both
analytically and numerically. These models may have both supersymmetry breaking
and supersymmetric vacua. Our interest is in determining the preferred vacuum.
We do so by computing the finite temperature Coleman-Weinberg potential and
studying its thermal evolution.


title: Generalized rank weights : a duality statement

abstract:
  We consider linear codes over some fixed finite field extension over an
arbitrary finite field. Gabidulin introduced rank metric codes, by endowing
linear codes over the extension field with a rank weight over the base field
and studied their basic properties in analogy with linear codes and the
classical Hamming distance. Inspired by the characterization of wiretap II
codes in terms of generalized Hamming weights by Wei, Kurihara et al. defined
some generalized rank weights and showed their relevance for secure network
coding. In this paper, we derive a statement for generalized rank weights of
the dual code, completely analogous to Wei's one for generalized Hamming
weights and we characterize the equality case of the r-generalized Singleton
bound for the generalized rank weights, in terms of the rank weight of the dual
code.


title:
Time-reversal symmetry and fluctuation relations in non-equilibrium
  quantum steady states

abstract:
  In this note, we present a simple derivation, from time-reversal symmetry, of
fluctuation relations for steady-state large deviation functions in
non-equilibrium quantum systems. We further show that a condition of pure
transmission implies extended fluctuation relations, connecting large deviation
functions to mean currents at shifted temperatures and chemical potentials. We
illustrate these concepts in various examples, including the interacting
resonant level model and conformal or integrable models.


title:
Advanced LIGO's ability to detect apparent violations of the cosmic
  censorship conjecture and the no-hair theorem through compact binary
  coalescence detections

abstract:
  We study the ability of the advanced Laser Interferometer Gravitational-wave
Observatory (aLIGO) to detect apparent violations of the cosmic censorship
conjecture and the no-hair theorem. The cosmic censorship conjecture, which is
believed to be true in the theory of general relativity, limits the
spin-to-mass-squared ratio of a Kerr black hole. The no-hair theorem, which is
also believed to be true in the theory of general relativity, suggests a
particular value for the tidal Love number of a non-rotating black hole. Using
the Fisher matrix formalism, we examine the measurability of the spin and tidal
deformability of compact binary systems involving at least one putative black
hole. Using parameter measurement errors and correlations obtained from the
Fisher matrix, we determine the smallest detectable violation of bounds implied
by the cosmic censorship conjecture and the no-hair theorem. We examine the
effect of excluding unphysical areas of parameter space when determining the
smallest detectable apparent violations, and we examine the effect of different
post-Newtonian corrections to the amplitude of the compact binary coalescence
gravitational waveform. In addition, we perform a brief study of how the
recently calculated 3.0 pN and 3.5 pN spin-orbit corrections to the phase
affect spin and mass parameter measurability. We find that physical priors on
the symmetric mass ratio and higher harmonics in the gravitational waveform
could significantly affect the ability of aLIGO to investigate cosmic
censorship and the no-hair theorem for certain systems.


title: Scattering of an exponential pulse by a single atom

abstract:
  We discuss the scattering of a light pulse by a single atom in free space
using a purely semi-classical framework. The atom is treated as a linear
elastic scatterer allowing to treat each spectral component of the incident
pulse separately. For an increasing exponential pulse with a dipole radiation
pattern incident from full solid angle the spectrum resulting from interference
of incident and scattered components is a decreasing exponential pulse.


title:
Designing an Efficient Delay Sensitive Routing Metric for IEEE 802.16
  Mesh Networks

abstract:
  Quality of Service provisioning is one of the major design goals of IEEE
802.16 mesh networks. In order to provide quality delivery of delay sensitive
services such as voice, video etc., it is required to route such traffic over a
minimum delay path. In this paper we propose a routing metric for delay
sensitive services in IEEE 802.16 mesh networks. We design a new cross layer
routing metric, namely Expected Scheduler Delay (ESD), based on HoldOff
exponent and the current load at each node of the network. This proposed metric
takes into account the expected theoretical end-to-end delay of routing paths
as well as network congestion to find the best suited path. We propose an
efficient distributed scheme to calculate ESD and route the packets using
source routing mechanism based on ESD. The simulation results demonstrate that
our metric achieves reduced delay compared to a standard scheme used in IEEE
802.16 mesh, that takes hop count to find the path.


title:
Topological invariants of eigenvalue intersections and decrease of
  Wannier functions in graphene

abstract:
  We investigate the asymptotic decrease of the Wannier functions for the
valence and conduction band of graphene, both in the monolayer and the
multilayer case. Since the decrease of the Wannier functions is characterised
by the structure of the Bloch eigenspaces around the Dirac points, we introduce
a geometric invariant of the family of eigenspaces, baptised eigenspace
vorticity. We compare it with the pseudospin winding number. For every value $n
\in Z$ of the eigenspace vorticity, we exhibit a canonical model for the local
topology of the eigenspaces. With the help of these canonical models, we show
that the single band Wannier function $w$ satisfies $|w(x)| \leq \mathrm{const}
|x|^{- 2}$ as $|x| \rightarrow \infty$, both in monolayer and bilayer graphene.


title: Stability of Multi-Task Kernel Regression Algorithms

abstract:
  We study the stability properties of nonlinear multi-task regression in
reproducing Hilbert spaces with operator-valued kernels. Such kernels, a.k.a.
multi-task kernels, are appropriate for learning prob- lems with nonscalar
outputs like multi-task learning and structured out- put prediction. We show
that multi-task kernel regression algorithms are uniformly stable in the
general case of infinite-dimensional output spaces. We then derive under mild
assumption on the kernel generaliza- tion bounds of such algorithms, and we
show their consistency even with non Hilbert-Schmidt operator-valued kernels .
We demonstrate how to apply the results to various multi-task kernel regression
methods such as vector-valued SVR and functional ridge regression.


title: Non-Monotonic Snapshot Isolation

abstract:
  Many distributed applications require transactions. However, transactional
protocols that require strong synchronization are costly in large scale
environments. Two properties help with scalability of a transactional system:
genuine partial replication (GPR), which leverages the intrinsic parallelism of
a workload, and snapshot isolation (SI), which decreases the need for
synchronization. We show that, under standard assumptions (data store accesses
are not known in advance, and transactions may access arbitrary objects in the
data store), it is impossible to have both SI and GPR. To circumvent this
impossibility, we propose a weaker consistency criterion, called Non-monotonic
Snapshot Isolation (NMSI). NMSI retains the most important properties of SI,
i.e., read-only transactions always commit, and two write-conflicting updates
do not both commit. We present a GPR protocol that ensures NMSI, and has lower
message cost (i.e., it contacts fewer replicas and/or commits faster) than
previous approaches.


title: Theoretical Procedures and the effect on PDFs and $\alpha_S(M_Z^2)$

abstract:
  I consider the effect on partons distribution functions (PDFs) of changes in
the theoretical procedure used in a PDF fit. I consider using the 3-flavour
fixed flavour number scheme instead of the standard general mass variable
flavour number scheme used in the MSTW analysis. This results in the light
quarks increasing at most $x$ values, the gluon distribution becoming softer at
high values of $x$ and larger at small $x$, and the coupling constant
$\alpha_S(M_Z^2)$ falling, particularly at NNLO. The fit quality also
deteriorates.I also consider lowering the kinematic cut on $W^2$ for DIS data
and introducing higher twist terms which are fit to data. This results in much
smaller effects on both PDFs and $\alpha_S(M_Z^2)$, with changes generally
smaller than uncertainties, except for quarks at very high $x$. I show that the
fixed flavour scheme and variable flavour scheme structure functions differ
significantly for $x \sim 0.01$ at high $Q^2$. I demonstrate that in the fixed
flavour scheme there is a slow convergence of large logarithmic terms of the
form $(\alpha_S\ln(Q^2/m_c^2))^n$ in this regime. I conclude that some major
differences in PDF sets are largely due to the choice of flavour scheme used.


title:
Poor Man's Understanding of Kinks Originating from Strong Electronic
  Correlations

abstract:
  By means of dynamical mean field theory calculations, it was recently
discovered that kinks generically arise in strongly correlated systems, even in
the absence of external bosonic degrees of freedoms such as phonons. However,
the physical mechanism behind these kinks remained unclear. On the basis of the
perturbative and numerical renormalization group theory, we herewith identify
these kinks as the effective Kondo energy scale of the interacting lattice
system which is shown to be smaller than the width of the central peak.


title:
Copula-based Randomized Mechanisms for Truthful Scheduling on Two
  Unrelated Machines

abstract:
  We design a Copula-based generic randomized truthful mechanism for scheduling
on two unrelated machines with approximation ratio within $[1.5852, 1.58606]$,
offering an improved upper bound for the two-machine case. Moreover, we provide
an upper bound 1.5067711 for the two-machine two-task case, which is almost
tight in view of the lower bound of 1.506 for the scale-free truthful
mechanisms [4]. Of independent interest is the explicit incorporation of the
concept of Copula in the design and analysis of the proposed approximation
algorithm. We hope that techniques like this one will also prove useful in
solving other problems in the future.


title: Diameter graphs in $\mathbb R^4$

abstract:
  A \textit{diameter graph in $\mathbb R^d$} is a graph, whose set of vertices
is a finite subset of $\mathbb R^d$ and whose set of edges is formed by pairs
of vertices that are at diameter apart. This paper is devoted to the study of
different extremal properties of diameter graphs in $\mathbb R^4$ and on a
three-dimensional sphere. We prove an analogue of V\'azsonyi's and Borsuk's
conjecture for diameter graphs on a three-dimensional sphere with radius
greater than $1/\sqrt 2$. We prove Schur's conjecture for diameter graphs in
$\mathbb R^4.$ We also establish the maximum number of triangles a diameter
graph in $\mathbb R^4$ can have, showing that the extremum is attained only on
specific Lenz configurations.


title:
On parallel implementation of Sequential Monte Carlo methods: the island
  particle model

abstract:
  The approximation of the Feynman-Kac semigroups by systems of interacting
particles is a very active research field, with applications in many different
areas. In this paper, we study the parallelization of such approximations. The
total population of particles is divided into sub-populations, referred to as
\emph{islands}. The particles within each island follow the usual selection /
mutation dynamics. We show that the evolution of each island is also driven by
a Feynman-Kac semigroup, whose transition and potential can be explicitly
related to ones of the original problem. Therefore, the same genetic type
approximation of the Feynman-Kac semi-group may be used at the island level;
each island might undergo selection / mutation algorithm. We investigate the
impact of the population size within each island and the number of islands, and
study different type of interactions. We find conditions under which
introducing interactions between islands is beneficial. The theoretical results
are supported by some Monte Carlo experiments.


title: Review of Recent Neutrino Physics Research

abstract:
  We review recent research in neutrino physics, including neutrino
oscillations to test time reversal and CP symmetry violations, the measurement
of parameters in the U matrix, sterile neutrino emission causing pulsar kicks,
and neutrino energies in the neutrinosphere.


title:
Observation of Squeezing in the Electron Quantum Shot Noise of a Tunnel
  Junction

abstract:
  We report the measurement of the fluctuations of the two quadratures of the
electromagnetic field generated by a quantum conductor, a dc- and ac-biased
tunnel junction placed at very low temperature.We observe that the variance of
the fluctuations on one quadrature can go below that of vacuum, i.e., that the
radiated field is squeezed. This demonstrates the quantum nature of the
radiated electromagnetic field.


title:
Time- and Frequency-Varying $K$-Factor of Non-Stationary Vehicular
  Channels for Safety Relevant Scenarios

abstract:
  Vehicular communication channels are characterized by a non-stationary time-
and frequency-selective fading process due to fast changes in the environment.
We characterize the distribution of the envelope of the first delay bin in
vehicle-to-vehicle channels by means of its Rician $K$-factor. We analyze the
time-frequency variability of this channel parameter using vehicular channel
measurements at 5.6 GHz with a bandwidth of 240 MHz for safety-relevant
scenarios in intelligent transportation systems (ITS). This data enables a
frequency-variability analysis from an IEEE 802.11p system point of view, which
uses 10 MHz channels. We show that the small-scale fading of the envelope of
the first delay bin is Ricean distributed with a varying $K$-factor. The later
delay bins are Rayleigh distributed. We demonstrate that the $K$-factor cannot
be assumed to be constant in time and frequency. The causes of these variations
are the frequency-varying antenna radiation patterns as well as the
time-varying number of active scatterers, and the effects of vegetation. We
also present a simple but accurate bi-modal Gaussian mixture model, that allows
to capture the $K$-factor variability in time for safety-relevant ITS
scenarios.


title: Discrete Homology Theory for Metric Spaces

abstract:
  In this paper we define and study a notion of discrete homology theory for
metric spaces. Instead of working with simplicial homology, our chain complexes
are given by Lipschitz maps from an $n$-dimensional cube to a fixed metric
space. We prove that the resulting homology theory verifies a discrete analogue
of the Eilenberg-Steenrod axioms, and prove a discrete analogue of the
Mayer-Vietoris exact sequence. Moreover, this discrete homology theory is
related to the discrete homotopy theory of a metric space through a discrete
analogue of the Hurewicz theorem. We study the class of groups that can arise
as discrete homology groups and, in this setting, we prove that the fundamental
group of a smooth, connected, metrizable, compact manifold is isomorphic to the
discrete fundamental group of a `fine enough' rectangulation of the manifold.
Finally, we show that this discrete homology theory can be coarsened, leading
to a new non-trivial coarse invariant of a metric space.


title: Two notions of unit distance graphs

abstract:
  A {\em faithful (unit) distance graph} in $\mathbb{R}^d$ is a graph whose set
of vertices is a finite subset of the $d$-dimensional Euclidean space, where
two vertices are adjacent if and only if the Euclidean distance between them is
exactly $1$. A {\em (unit) distance graph} in $\mathbb{R}^d$ is any subgraph of
such a graph. In the first part of the paper we focus on the differences
between these two classes of graphs. In particular, we show that for any fixed
$d$ the number of faithful distance graphs in $\mathbb{R}^d$ on $n$ labelled
vertices is $2^{(1+o(1)) d n \log_2 n}$, and give a short proof of the known
fact that the number of distance graphs in $\mathbb{R}^d$ on $n$ labelled
vertices is $2^{(1-1/\lfloor d/2 \rfloor +o(1))n^2/2}$. We also study the
behavior of several Ramsey-type quantities involving these graphs. % and
high-girth graphs from these classes. In the second part of the paper we
discuss the problem of determining the minimum possible number of edges of a
graph which is not isomorphic to a faithful distance graph in $\mathbb R^d$.


title: On Finding the Largest Mean Among Many

abstract:
  Sampling from distributions to find the one with the largest mean arises in a
broad range of applications, and it can be mathematically modeled as a
multi-armed bandit problem in which each distribution is associated with an
arm. This paper studies the sample complexity of identifying the best arm
(largest mean) in a multi-armed bandit problem. Motivated by large-scale
applications, we are especially interested in identifying situations where the
total number of samples that are necessary and sufficient to find the best arm
scale linearly with the number of arms. We present a single-parameter
multi-armed bandit model that spans the range from linear to superlinear sample
complexity. We also give a new algorithm for best arm identification, called
PRISM, with linear sample complexity for a wide range of mean distributions.
The algorithm, like most exploration procedures for multi-armed bandits, is
adaptive in the sense that the next arms to sample are selected based on
previous samples. We compare the sample complexity of adaptive procedures with
simpler non-adaptive procedures using new lower bounds. For many problem
instances, the increased sample complexity required by non-adaptive procedures
is a polynomial factor of the number of arms.


title: Functional renormalization of N scalars with O(N) invariance

abstract:
  We discuss general theories of N scalar fields with O(N) symmetry. In
addition to the standard case of linearly realized symmetry there are also
examples that carry nonlinear realizations, with the topology of a cylinder
$R\times S^{N-1}$ or a sphere $S^N$. We write flow equations for the theory in
the second order of the derivative expansion in the background field and
discuss the properties of scaling solutions with vanishing potential.


title: Holomorphic projections and Ramanujan's mock theta functions

abstract:
  We employ spectral methods of automorphic forms to establish a holomorphic
projection operator for tensor products of vector-valued harmonic weak Maass
forms and vector-valued modular forms. We apply this operator to discover
simple recursions for Fourier series coefficients of Ramanujan's mock theta
functions.


title: Discriminating word senses with tourist walks in complex networks

abstract:
  Patterns of topological arrangement are widely used for both animal and human
brains in the learning process. Nevertheless, automatic learning techniques
frequently overlook these patterns. In this paper, we apply a learning
technique based on the structural organization of the data in the attribute
space to the problem of discriminating the senses of 10 polysemous words. Using
two types of characterization of meanings, namely semantical and topological
approaches, we have observed significative accuracy rates in identifying the
suitable meanings in both techniques. Most importantly, we have found that the
characterization based on the deterministic tourist walk improves the
disambiguation process when one compares with the discrimination achieved with
traditional complex networks measurements such as assortativity and clustering
coefficient. To our knowledge, this is the first time that such deterministic
walk has been applied to such a kind of problem. Therefore, our finding
suggests that the tourist walk characterization may be useful in other related
applications.


title: Distance graphs with large chromatic number and arbitrary girth

abstract:
  In this article we consider a problem related to two famous combinatorial
topics. One of them concerns the chromatic number of the space. The other deals
with graphs having big girth (the length of the shortest cycle) and large
chromatic number. Namely, we prove that for any $l\in \mathbb{N}$ there exists
a sequence of distance graphs in $\mathbb{R}^n$ with girth at least $l$ and the
chromatic number equal to $(c+\bar{o}(1))^n$ with $c>1$.


title: Higgs-Z-photon Coupling from Effect of Composite Resonances

abstract:
  We explore the Higgs-Z-photon coupling in the Minimal Composite Higgs Model
with vector and axial resonances. The electroweak precision measurement, i.e. S
and T, is estimated for this model. We calculate the signal strength for Higgs
decay into Z-photon and notable enhancement is found in certain EWPT allowed
parameter region.


title:
Applying the Wiener-Hopf Monte Carlo simulation technique for Levy
  processes to path functionals such as first passage times, undershoots and
  overshoots

abstract:
  In this note we apply the recently established Wiener-Hopf Monte Carlo (WHMC)
simulation technique for Levy processes from Kuznetsov et al. [17] to path
functionals, in particular first passage times, overshoots, undershoots and the
last maximum before the passage time. Such functionals have many applications,
for instance in finance (the pricing of exotic options in a Levy model) and
insurance (ruin time, debt at ruin and related quantities for a Levy insurance
risk process). The technique works for any Levy process whose running infimum
and supremum evaluated at an independent exponential time allows sampling from.
This includes classic examples such as stable processes, subclasses of
spectrally one sided Levy processes and large new families such as meromorphic
Levy processes. Finally we present some examples. A particular aspect that is
illustrated is that the WHMC simulation technique performs much better at
approximating first passage times than a `plain' Monte Carlo simulation
technique based on sampling increments of the Levy process.


title: Non-Gaussian, non-dynamical stochastic resonance

abstract:
  The archetypal system demonstrating stochastic resonance is nothing more than
a threshold triggered device. It consists of a periodic modulated input and
noise. Every time an output crosses the threshold the signal is recorded. Such
a digitally filtered signal is sensitive to the noise intensity. There exist
the optimal value of the noise intensity resulting in the "most" periodic
output. Here, we explore properties of the non-dynamical stochastic resonance
in non-equilibrium situations, i.e. when the Gaussian noise is replaced by an
$\alpha$-stable noise. We demonstrate that non-equilibrium $\alpha$-stable
noises, depending on noise parameters, can either weaken or enhance the
non-dynamical stochastic resonance.


title: Recurrence Theorems: a unified account

abstract:
  I discuss classical and quantum recurrence theorems in a unified manner,
treating both as generalisations of the fact that a system with a finite state
space only has so many places to go. Along the way I prove versions of the
recurrence theorem applicable to dynamics on linear and metric spaces, and make
some comments about applications of the classical recurrence theorem in the
foundations of statistical mechanics.


title:
Higher Order Corrections to the Trilinear Higgs Self-Couplings in the
  Real NMSSM

abstract:
  After the discovery of a Higgs-like boson by the LHC experiments ATLAS and
CMS, it is of crucial importance to determine its properties in order to not
only identify it as the boson responsible for electroweak symmetry breaking but
also to clarify the question if it is a Standard Model (SM) Higgs boson or the
Higgs particle of some extension beyond the SM as {\it e.g.} supersymmetry. In
this context, the precise prediction of the Higgs parameters as masses and
couplings play a crucial role for the proper distinction between different
models. In extension of previous works on the loop-corrected Higgs boson masses
of the Next-to-Minimal Supersymmetric Extension of the SM (NMSSM), we present
here the calculation of the loop-corrected trilinear NMSSM Higgs
self-couplings. The loop corrections turn out to have a substantial impact on
the decay widths of Higgs-to-Higgs decays and on the production cross section
of Higgs pairs via gluon fusion. They are therefore indispensable for the
correct interpretation of the experimental Higgs results.


title:
Cost Effectiveness Statistic: A Proposal To Take Into Account The
  Patient Stratification Factors

abstract:
  The solution here proposed can be used to conduct economic analysis in
randomized clinical trials. It is based on a statistical approach and aims at
calculating a revised version of the incremental costeffective ratio (ICER) in
order to take into account the key factors that can influence the choice of
therapy causing confounding by indication. Let us take as an example a new
therapy to treat cancer being compared to an existing therapy with
effectiveness taken as time to death. A challenging problem is that the ICER is
defined in terms of means over the entire treatment groups. It makes no
provision for stratification by groups of patients with differing risk of
death. For example, for a fair and unbiased analysis, one would desire to
compare time to death in groups with similar life expectancy which would be
impacted by factors such as age, gender, disease severity, etc. The method we
decided to apply is borrowed by cluster analysis and aims at (i) discard any
outliers in the set under analysis that may arise, (ii) identify groups (i.e.
clusters) of patients with "similar" key factors.


title:
Semigroups of Operators on Spaces of Fuzzy-Number-Valued Functions with
  Applications to Fuzzy Differential Equations

abstract:
  In this paper we introduce and study semigroups of operators on spaces of
fuzzy-number-valued functions, and various applications to fuzzy differential
equations are presented. Starting from the space of fuzzy numbers, many new
spaces sharing the same properties are introduced. We derive basic operator
theory results on these spaces and new results in the theory of semigroups of
linear operators on fuzzy-number kind spaces. The theory we develop is used to
solve classical fuzzy systems of differential equations, including, for
example, the fuzzy Cauchy problem and the fuzzy wave equation. These tools
allow us to obtain explicit solutions to fuzzy initial value problems which
bear explicit formulas similar to the crisp case, with some additional fuzzy
terms which in the crisp case disappear. The semigroup method displays a clear
advantage over other methods available in the literature (i.e., the level set
method, the differential inclusions method and other "fuzzification" methods of
the real-valued solution) in the sense that the solutions can be easily
constructed, and that the method can be applied to a larger class of fuzzy
differential equations that can be transformed into an abstract Cauchy problem.


title: Causality constraints on TMD PDF

abstract:
  In this short note, we discuss constraints on the transverse momentum
dependent factorization formulae coming from the causality properties for the
hadronic tensor.


title:
A dependent multiplier bootstrap for the sequential empirical copula
  process under strong mixing

abstract:
  Two key ingredients to carry out inference on the copula of multivariate
observations are the empirical copula process and an appropriate resampling
scheme for the latter. Among the existing techniques used for i.i.d.
observations, the multiplier bootstrap of R\'{e}millard and Scaillet (J.
Multivariate Anal. 100 (2009) 377-386) frequently appears to lead to inference
procedures with the best finite-sample properties. B\"{u}cher and Ruppert (J.
Multivariate Anal. 116 (2013) 208-229) recently proposed an extension of this
technique to strictly stationary strongly mixing observations by adapting the
dependent multiplier bootstrap of B\"{u}hlmann (The blockwise bootstrap in time
series and empirical processes (1993) ETH Z\"{u}rich, Section 3.3) to the
empirical copula process. The main contribution of this work is a
generalization of the multiplier resampling scheme proposed by B\"{u}cher and
Ruppert along two directions. First, the resampling scheme is now genuinely
sequential, thereby allowing to transpose to the strongly mixing setting many
of the existing multiplier tests on the unknown copula, including nonparametric
tests for change-point detection. Second, the resampling scheme is now fully
automatic as a data-adaptive procedure is proposed which can be used to
estimate the bandwidth parameter. A simulation study is used to investigate the
finite-sample performance of the resampling scheme and provides suggestions on
how to choose several additional parameters. As by-products of this work, the
validity of a sequential version of the dependent multiplier bootstrap for
empirical processes of B\"{u}hlmann is obtained under weaker conditions on the
strong mixing coefficients and the multipliers, and the weak convergence of the
sequential empirical copula process is established under many serial dependence
conditions.


title:
Direct in-situ observation of structural transition driven actuation in
  VO2 utilizing electron transparent cantilevers

abstract:
  Direct imaging and quantification of actuation in nanostructures that undergo
structural phase transitions could advance our understanding of collective
phenomena in the solid state. Here, we demonstrate visualization of structural
phase transition induced actuation in a model correlated insulator vanadium
dioxide by in-situ Fresnel contrast imaging of electron transparent
cantilevers. We quantify abrupt, reversible cantilever motion occurring due to
the stress relaxation across the structural transition from monoclinic to
tetragonal phase with increasing temperature. Deflections measured in such
nanoscale cantilevers can be directly correlated with macroscopic stress
measurements by wafer curvature studies as well as temperature dependent
electrical conduction allowing one to interrogate lattice dynamics across
length scales.


title:
Influence of a Critical Point on Hydrodynamic Fluctuations in Heavy Ion
  Collisions

abstract:
  Hydrodynamic fluctuations have been studied in a wide variety of physical,
chemical, and biological phenomena in the past decade. In high energy heavy ion
collisions, there will be intrinsic fluctuations even if the initial conditions
are fixed. Fluctuations will be greatly enhanced if the trajectory in the plane
of temperature versus chemical potential passes near a critical point. We
construct a model for the thermal conductivity which diverges at the critical
point with the correct critical exponents, and use it in a simple illustrative
model of a heavy ion collision. The proton correlation function is sensitive to
the presence of the critical point.


title:
Direct leaf trajectory optimization for volumetric modulated arc therapy
  planning with sliding window delivery

abstract:
  We propose a novel optimization model for volumetric modulated arc therapy
(VMAT) planning that directly optimizes deliverable leaf trajectories in the
treatment plan optimization problem, and eliminates the need for a separate
arc-sequencing step. In this model, a 360-degree arc is divided into a given
number of arc segments in which the leaves move unidirectionally. This
facilitates an algorithm that determines the optimal piecewise linear leaf
trajectories for each arc segment, which are deliverable in a given treatment
time. Multi-leaf collimator (MLC) constraints, including maximum leaf speed and
interdigitation, are accounted for explicitly. The algorithm is customized to
allow for VMAT delivery using constant gantry speed and dose rate, however, the
algorithm generalizes to variable gantry speed if beneficial. We demonstrate
the method for three different tumor sites: a head-and-neck case, a prostate
case, and a paraspinal case. For that purpose, we first obtain a reference plan
for intensity modulated radiotherapy (IMRT) using fluence map optimization and
20 equally spaced beam directions. Subsequently, VMAT plans are optimized by
dividing the 360-degree arc into 20 corresponding arc segments. Assuming
typical machine parameters (a dose rate of 600 MU/min, and a maximum leaf speed
of 3 cm/sec), it is demonstrated that the quality of the optimized VMAT plans
approaches the quality of the IMRT benchmark plan for delivery times between 3
and 4 minutes.


title:
On singularity as a function of time of a conditional distribution of an
  exit time

abstract:
  We establish the singularity with respect to Lebesgue measure as a function
of time of the conditional probability that the sum of two one-dimensional
Brownian motions will exit from the unit interval before time $t$, given the
trajectory of the second Brownian motion up to the same time. On the way of
doing so we show that if one solves the one-dimensional heat equation with zero
condition on a trajectory of a one-dimensional Brownian motion, which is the
lateral boundary, then for each moment of time with probability one the normal
derivative of the solution is zero, provided that the diffusion of the Brownian
motion is sufficiently large.


title: Tubular Jacobian Algebras

abstract:
  We show that the endomorphism ring of each cluster tilting object in a
tubular cluster category is a finite dimensional Jacobian algebra which is tame
of polynomial growth. Moreover, these Jacobian algebras are given by a quiver
with a non-degenerate potential and mutation of cluster tilting objects is
compatible with mutation of QPs.


title: On $(\alpha_n)$-regular sets

abstract:
  We define $(\alpha_n)$ -regular sets in uniformly perfect metric spaces. This
definition is quasisymmetrically invariant and the construction resembles
generalized dyadic cubes in metric spaces. For these sets we then determine the
necessary and sufficient conditions to be fat (or thin). In addition we discuss
restrictions of doubling measures to these sets, and in particular give a
sufficient condition to retain at least some of the restricted measures
doubling on the set. Our main result generalizes and extends analogous results
that were previously known to hold in the real-line.


title: Streaming instability in the quasi-global protoplanetary discs

abstract:
  We investigate streaming instability using two-fluid approximation (neutral
gas and dust) in a quasi-global, unstratified protoplanetary disc, with the
help of PIERNIK code. We compare amplification rate of the eigen-mode in
numerical simulations, with the corresponding growth resulting from the linear
stability analysis of full system of Euler's equation including aerodynamic
drag. Following Youdin & Goodman (2005) we show that (1) rapid dust clumping
occurs due to the difference in azimuthal velocities of gas and dust, coupled
by the drag force, (2) initial density perturbations are amplified by several
orders of magnitude. We demonstrate that the multi-fluid extension of the
simple and efficient Relaxing TVD scheme, implemented in PIERNIK, leads to
results, which are compatible with those obtained with other methods.


title: Coset conformal field theory and instanton counting on C^2/Z_p

abstract:
  We study conformal field theory with the symmetry algebra
$\mathcal{A}(2,p)=\hat{\mathfrak{gl}}(n)_{2}/\hat{\mathfrak{gl}}(n-p)_2$. In
order to support the conjecture that this algebra acts on the moduli space of
instantons on $\mathbb{C}^{2}/\mathbb{Z}_{p}$, we calculate the characters of
its representations and check their coincidence with the generating functions
of the fixed points of the moduli space of instantons.
  We show that the algebra $\mathcal{A}(2,p)$ can be realized in two ways. The
first realization is connected with the cross-product of $p$ Virasoro and $p$
Heisenberg algebras: $\mathcal{H}^{p}\times \textrm{Vir}^{p}$. The second
realization is connected with: $\mathcal{H}^{p}\times
\hat{\mathfrak{sl}}(p)_2\times (\hat{\mathfrak{sl}}(2)_p \times
\hat{\mathfrak{sl}}(2)_{n-p}/\hat{\mathfrak{sl}}(2)_n)$. The equivalence of
these two realizations provides the non-trivial identity for the characters of
$\mathcal{A}(2,p)$.
  The moduli space of instantons on $\mathbb{C}^{2}/\mathbb{Z}_{p}$ admits two
different compactifications. This leads to two different bases for the
representations of $\mathcal{A}(2,p)$. We use this fact to explain the
existence of two forms of the instanton pure partition functions.


title:
Study of the impact of the post-MS evolution of the host star on the
  orbits of close-in planets. II. A giant planet in a close-in orbit around the
  RGB star HIP63242

abstract:
  Context: More than 40 planets have been found around giant stars, revealing a
lack of systems orbiting interior to $\sim$ 0.6 AU. This observational fact
contrasts with the planetary population around solar-type stars and has been
interpreted as the result of the orbital evolution of planets due to the
interaction with the host star and/or because of a different
formation/migration scenario of planets around more massive stars. Aims: We are
conducting a radial velocity study of a sample of 166 giant stars aimed at
studying the population of close-in planets orbiting post-main sequence stars.
METHODS: We have computed precision radial velocities from multi-epoch
spectroscopic data, in order to search for planets around giant stars. Results:
In this paper we present the discovery of a massive planet around the
intermediate-mass giant star HIP\,63242. The best keplerian fit to the data
lead to an orbital distance of 0.57 AU, an eccentricity of 0.23 and a projected
mass of 9.2 \mjup. HIP\,63242\,b is the innermost planet detected around any
intermediate-mass giant star and also the first planet detected in our survey.


title:
Clouds in the atmospheres of extrasolar planets. IV. On the scattering
  greenhouse effect of CO2 ice particles: Numerical radiative transfer studies

abstract:
  Owing to their wavelengths dependent absorption and scattering properties,
clouds have a strong impact on the climate of planetary atmospheres.
Especially, the potential greenhouse effect of CO2 ice clouds in the
atmospheres of terrestrial extrasolar planets is of particular interest because
it might influence the position and thus the extension of the outer boundary of
the classic habitable zone around main sequence stars.
  We study the radiative effects of CO2 ice particles obtained by different
numerical treatments to solve the radiative transfer equation. The comparison
between the results of a high-order discrete ordinate method and simpler
two-stream approaches reveals large deviations in terms of a potential
scattering efficiency of the greenhouse effect. The two-stream methods
overestimate the transmitted and reflected radiation, thereby yielding a higher
scattering greenhouse effect. For the particular case of a cool M-type dwarf
the CO2 ice particles show no strong effective scattering greenhouse effect by
using the high-order discrete ordinate method, whereas a positive net
greenhouse effect was found in case of the two-stream radiative transfer
schemes. As a result, previous studies on the effects of CO2 ice clouds using
two-stream approximations overrated the atmospheric warming caused by the
scattering greenhouse effect. Consequently, the scattering greenhouse effect of
CO2 ice particles seems to be less effective than previously estimated. In
general, higher order radiative transfer methods are necessary to describe the
effects of CO2 ice clouds accurately as indicated by our numerical radiative
transfer studies.


title: Phenomenological characterisation of semi-holographic non-Fermi liquids

abstract:
  We analyse some phenomenological implications of the most general
semi-holographic models for non-Fermi liquids that have emerged with inputs
from the holographic correspondence. We find generalizations of Landau-Silin
equations with few parameters governing thermodynamics, low energy response and
collective excitations. We show that even when there is a Fermi surface with
well-defined quasi-particle excitations, the collective excitations can behave
very differently from Landau's theory.