title:
Absorption and eigenmode calculation for one-dimensional periodic
  metallic structures using the hydrodynamic approximation

abstract:
  We develop a modal method that solves Maxwell's equations in the presence of
the linearized hydrodynamic correction. Using this approach, it is now possible
to calculate the full diffraction for structures with period of the order of
the plasma wavelength, including not only the transverse but also the
longitudinal modes appearing above the plasma frequency. As an example for
using this method we solve the diffraction of a plane wave near the plasma
frequency from a bi-metallic layer, modeled as a continuous variation of the
plasma frequency. We observe absorption oscillations around the plasma
frequency. The lower frequency absorption peaks and dips correspond to lowest
longitudinal modes concentrated in the lower plasma frequency region. As the
frequency is increased, higher order longitudinal modes are excited and extent
to the region of higher plasma frequency. Moreover, examination of the
propagation constants of these modes reveals that the absorption peaks and dips
are directly related to the direction of phase propagation of the longitudinal
modes. Furthermore, we formulate a variant of the Plane Wave Expansion method,
and used it to calculate the dispersion diagram of such longitudinal modes in a
periodically modulated plasma frequency layer.


title:
The soft component and the iron line as signatures of the disc inner
  radius in Galactic black hole binaries

abstract:
  The inner radius of the accretion disc around a black hole in the low/hard
state can be measured in one of two ways. Firstly, via the extent of broadening
of the iron emission line, and secondly, from the luminosity and temperature of
the weak soft component seen in this state, assuming it is the disc. We use
both of these methods on all the low/hard state spectra taken in timing mode of
XMM-Newton's EPIC-pn. We find that the two methods are not consistent with each
other, and the difference is not always in a single direction. The two methods
are neither model independent, nor are they independent of current calibration
issues. We find that the remaining small residuals in the EPIC-pn timing mode
response at the <3% level can have a dramatic effect on the fit parameters for
the reflected spectrum. There is also a mismatch in cross-calibration with
RXTE, which makes it difficult to use simultaneous data to extend the bandpass
of the spectral fits. Nonetheless, it is clear from the data that the iron line
is noticeably broader and stronger at higher L/LEdd, which is consistent with
the truncated disc models. We also show that it is likely that the soft
component changes character, from a stable component consistent with a
truncated disc at high L/LEdd, to a variable one with much smaller radius at
low L/LEdd. This adds to growing evidence for a complex soft component in the
low/hard state, possibly resulting from clumps torn from the edge of the
truncated disc.


title:
Evaluation of nitrogen- and silicon-vacancy defect centres as single
  photon sources in quantum key distribution

abstract:
  We demonstrate a quantum key distribution (QKD) testbed for room temperature
single photon sources based on defect centres in diamond. A BB84 protocol over
a short free-space transmission line is implemented. The performance of
nitrogen-vacancy (NV) as well as silicon-vacancy defect (SiV) centres is
evaluated and an extrapolation for next-generation sources with enhanced
efficiency is discussed.


title:
Spatially Scalable Compressed Image Sensing with Hybrid Transform and
  Inter-layer Prediction Model

abstract:
  Compressive imaging is an emerging application of compressed sensing, devoted
to acquisition, encoding and reconstruction of images using random projections
as measurements. In this paper we propose a novel method to provide a scalable
encoding of an image acquired by means of compressed sensing techniques. Two
bit-streams are generated to provide two distinct quality levels: a
low-resolution base layer and full-resolution enhancement layer. In the
proposed method we exploit a fast preview of the image at the encoder in order
to perform inter-layer prediction and encode the prediction residuals only. The
proposed method successfully provides resolution and quality scalability with
modest complexity and it provides gains in the quality of the reconstructed
images with respect to separate encoding of the quality layers. Remarkably, we
also show that the scheme can also provide significant gains with respect to a
direct, non-scalable system, thus accomplishing two features at once:
scalability and improved reconstruction performance.


title: A Novel (2+1)-Dimensional Model of Chiral Symmetry Breaking

abstract:
  We propose a new model of flavour chiral symmetry breaking in a
(2+1)-dimensional defect gauge theory of strongly coupled fermions by
introducing probe D5/anti-D5-flavour branes on the conifold. After working out
the flavour brane embeddings at zero temperature, we thoroughly investigate the
spectra of small fluctuations on the world volume of the flavour branes (meson
spectrum) and conclude that they are free of tachyons. Thus the proposed probe
brane embedding is stable. Moreover, we introduce finite temperature and an
external magnetic field and study the thermodynamics of the resulting
configurations. Namely, we compute the free energies, entropies, heat
capacities and magnetisations. The results are used to establish a detailed
phase diagram of the model. We find that the effect of magnetic catalysis of
chiral symmetry breaking is realised in our model and show that the
meson-melting phase transition coincides with the chiral symmetry breaking
phase transition. Furthermore, we show that the model is in a diamagnetic
phase.


title: Production and Transfer of Energy and Information in Hamiltonian Systems

abstract:
  We present novel results that relate energy and information transfer with
sensitivity to initial conditions in chaotic multi-dimensional Hamiltonian
systems. We show the relation among Kolmogorov-Sinai entropy, Lyapunov
exponents, and upper bounds for the Mutual Information Rate calculated in the
Hamiltonian phase space and on bi-dimensional subspaces. Our main result is
that the net amount of transfer from kinetic to potential energy per unit of
time is a power-law of the upper bound for the Mutual Information Rate between
kinetic and potential energies, and also a power-law of the Kolmogorov-Sinai
entropy. Therefore, transfer of energy is related with both transfer and
production of information. However, the power-law nature of this relation means
that a small increment of energy transferred leads to a relatively much larger
increase of the information exchanged. Then, we propose an ``experimental''
implementation of a 1-dimensional communication channel based on a Hamiltonian
system, and calculate the actual rate with which information is exchanged
between the first and last particle of the channel. Finally, a relation between
our results and important quantities of thermodynamics is presented.


title: Non-Abelian Vortices with an Aharonov-Bohm Effect

abstract:
  The interplay of gauge dynamics and flavor symmetries often leads to
remarkably subtle phenomena in the presence of soliton configurations.
Non-Abelian vortices -- vortex solutions with continuous internal orientational
moduli -- provide an example. Here we study the effect of weakly gauging a
U(1)_R subgroup of the flavor symmetry on such BPS vortex solutions. Our
prototypical setting consists of an SU(2) x U(1) gauge theory with N_f=2 sets
of fundamental scalars that break the gauge symmetry to an "electromagnetic"
U(1). The weak U(1)_R gauging converts the well-known CP1 orientation modulus
|B| of the non-Abelian vortex into a parameter characterizing the strength of
the magnetic field that is responsible for the Aharonov-Bohm effect. As the
phase of B remains a genuine zero mode while the electromagnetic gauge symmetry
is Higgsed in the interior of the vortex, these solutions are superconducting
strings.


title: Euler tours and unicycles in the rotor-router model

abstract:
  A recurrent state of the rotor-routing process on a finite sink-free graph
can be represented by a unicycle that is a connected spanning subgraph
containing a unique directed cycle. We distinguish between short cycles of
length 2 called "dimers" and longer ones called "contours". Then the
rotor-router walk performing an Euler tour on the graph generates a sequence of
dimers and contours which exhibits both random and regular properties. Imposing
initial conditions randomly chosen from the uniform distribution we calculate
expected numbers of dimers and contours and correlation between them at two
successive moments of time in the sequence. On the other hand, we prove that
the excess of the number of contours over dimers is an invariant depending on
planarity of the subgraph but not on initial conditions. In addition, we
analyze the mean-square displacement of the rotor-router walker in the
recurrent state.


title: On ordinary crystals with logarithmic poles

abstract:
  We derive some local properties of abstract crystals with logarithmic poles
over a smooth base in positive characteristic and obtain the existence of the
canonical coordinates of certain ordinary crystals. We then apply the results
to deduce an integral property of the coefficients of the so-called mirror
maps.


title: The Novel Approach of Adaptive Twin Probability for Genetic Algorithm

abstract:
  The performance of GA is measured and analyzed in terms of its performance
parameters against variations in its genetic operators and associated
parameters. Since last four decades huge numbers of researchers have been
working on the performance of GA and its enhancement. This earlier research
work on analyzing the performance of GA enforces the need to further
investigate the exploration and exploitation characteristics and observe its
impact on the behavior and overall performance of GA. This paper introduces the
novel approach of adaptive twin probability associated with the advanced twin
operator that enhances the performance of GA. The design of the advanced twin
operator is extrapolated from the twin offspring birth due to single ovulation
in natural genetic systems as mentioned in the earlier works. The twin
probability of this operator is adaptively varied based on the fitness of best
individual thereby relieving the GA user from statically defining its value.
This novel approach of adaptive twin probability is experimented and tested on
the standard benchmark optimization test functions. The experimental results
show the increased accuracy in terms of the best individual and reduced
convergence time.


title:
Homodyne tomography of a single photon retrieved on demand from a
  cavity-enhanced cold atom memory

abstract:
  We experimentally demonstrate that a non-classical state prepared in an
atomic memory can be efficiently transferred to a single mode of
free-propagating light. By retrieving on demand a single excitation from a cold
atomic gas, we realize an efficient source of single photons prepared in a
pure, fully controlled quantum state. We characterize this source using two
detection methods, one based on photon-counting analysis, and the second using
homodyne tomography to reconstruct the density matrix and Wigner function of
the state. The latter technique allows us to completely determine the mode of
the retrieved photon in its fine phase and amplitude details, and demonstrate
its nonclassical field statistics by observing a negative Wigner function. We
measure a photon retrieval efficiency up to 82% and an atomic memory coherence
time of 900 ns. This setup is very well suited to study interactions between
atomic excitations, and to use them in order to create and manipulate more
sophisticated quantum states of light with a high degree of experimental
control.


title: Grain Destruction in a Supernova Remnant Shock Wave

abstract:
  Dust grains are sputtered away in the hot gas behind shock fronts in
supernova remnants, gradually enriching the gas phase with refractory elements.
We have measured emission in C IV $\lambda$1550 from C atoms sputtered from
dust in the gas behind a non-radiative shock wave in the northern Cygnus Loop.
Overall, the intensity observed behind the shock agrees approximately with
predictions from model calculations that match the Spitzer 24 micron and the
X-ray intensity profiles. Thus these observations confirm the overall picture
of dust destruction in SNR shocks and the sputtering rates used in models.
However, there is a discrepancy in that the CIV intensity 10" behind the shock
is too high compared to the intensities at the shock and 25" behind it.
Variations in the density, hydrogen neutral fraction and the dust properties
over parsec scales in the pre-shock medium limit our ability to test dust
destruction models in detail.


title: Latest NIKA results and the NIKA-2 project

abstract:
  NIKA (New IRAM KID Arrays) is a dual-band imaging instrument installed at the
IRAM (Institut de RadioAstronomie Millimetrique) 30-meter telescope at Pico
Veleta (Spain). Two distinct Kinetic Inductance Detectors (KID) focal planes
allow the camera to simultaneously image a field-of-view of about 2 arc-min in
the bands 125 to 175 GHz (150 GHz) and 200 to 280 GHz (240 GHz). The
sensitivity and stability achieved during the last commissioning Run in June
2013 allows opening the instrument to general observers. We report here the
latest results, in particular in terms of sensitivity, now comparable to the
state-of-the-art Transition Edge Sensors (TES) bolometers, relative and
absolute photometry. We describe briefly the next generation NIKA-2 instrument,
selected by IRAM to occupy, from 2015, the continuum imager/polarimeter slot at
the 30-m telescope.


title:
Optimization of quantum cascade laser operation by geometric design of
  cascade active band in open and closed models

abstract:
  Using the effective mass and rectangular potential approximations, the theory
of electron dynamic conductivity is developed for the plane multilayer
resonance tunnel structure placed into a constant electric field within the
model of open nanosystem, and oscillator forces of quantum transitions within
the model of closed nanosystem. For the experimentally produced quantum cascade
laser with four-barrier active band of separate cascade, it is proven that just
the theory of dynamic conductivity in the model of open cascade most adequately
describes the radiation of high frequency electromagnetic field while the
electrons transport through the resonance tunnel structure driven by a constant
electric field.


title:
Effect of quantum dot shape of the GaAs/AlAs heterostructure on
  interlevel hole light absorption

abstract:
  The effect of quantum dot shape on the hole energy spectrum and optical
properties caused by the interlevel charge transition based on the 4x4
Hamiltonian has been studied for the GaAs quantum dot in the AlAs semiconductor
matrix. Calculations have been carried out in perturbation theory taking into
account the hybridization of states for cubic, ellipsoidal, cylindrical and
tetrahedral shapes by changing the volume of a quantum dot. Based on the energy
calculations and on the determined wave functions of the hole states we have
defined the selection rules and the dependence of the interlevel hole
absorption coefficient on QD shapes and volumes.


title:
Density functional theory study of the {\alpha} --> {\omega} martensitic
  transformation in titanium induced by hydrostatic pressure

abstract:
  The martensitic {\alpha} --> {\omega} transition was investigated in Ti under
hydrostatic pressure. The calculations were carried out using the density
functional theory (DFT) framework in combination with the Birch-Murnaghan
equation of state. The calculated ground-state properties of {\alpha} and
{\omega} phases of Ti, their bulk moduli and pressure derivatives are in
agreement with the previous experimental data. The lattice constants of
{\alpha} and {\omega}-phase at 0 K were modeled as a function of pressure from
0 to 74 GPa and 0 to 119 GPa, respectively. It is shown that the lattice
constants vary in a nonlinear manner upon compression. The calculated lattice
parameters were used to describe the {\alpha} --> {\omega} transition and show
that the phase transition can be obtained at 0 GPa and 0 K.


title: Magnetic states of single impurity in disordered environment

abstract:
  The charged and magnetic states of isolated impurities dissolved in amorphous
metallic alloy are investigated. The Hamiltonian of the system under study is
the generalization of Anderson impurity model. Namely, the processes of elastic
and non-elastic scattering of conductive electrons on the ions of a metal and
on a charged impurity are included. The configuration averaged one-particle
Green's functions are obtained within Hartree-Fock approximation. A system of
self-consistent equations is given for calculation of an electronic spectrum,
the charged and the spin-polarized impurity states. Qualitative analysis of the
effect of the metallic host structural disorder on the observed values is
performed. Additional shift and broadening of virtual impurity level is caused
by a structural disorder of impurity environment.


title:
Numerical analysis of the morphological and phase changes in the
  TiN/Al_{2}O_{3} coating under high current electron beam modification

abstract:
  A modification of the surface structure of the hybrid coating TiN/Al_{2}O_{3}
with a low-energy high-current electron beam (NCEB) is performed. The surface
roughness is considered as a function of beam current. Surfaces of the obtained
samples are investigated within the two-dimensional multifractal detrended
fluctuation analysis (MF-DFA). The multifractal spectrum of the surface is
calculated as a quantitative parameter of the roughness. It is shown that with
an increase of the beam energy, the surface becomes more regular and uniform.


title:
Bath dynamics in an exactly solvable qubit model with initial
  qubit-environment correlations

abstract:
  We study the bath dynamics in the dephasing model of a two-state quantum
system (qubit) coupled to an environment of harmonic oscillators. This model
was shown [Morozov et al., Phys. Rev. A, 2012, 85, 022101] to admit the
analytic solution for the qubit and environment dynamics. Using this solution,
we derive the exact expression for the bath reduced density matrix in the
presence of initial qubit-environment correlations. We obtain the
non-equilibrium phonon distribution function and discuss in detail the time
behavior of the bath energy. It is shown that only the inclusion of dynamic
correlations between the qubit and the bath ensures the proper time behavior of
the quantity which may be interpreted as the "environment energy".


title:
Strain energy calculations of hexagonal boron nanotubes: An ab-initio
  approach

abstract:
  An ab initio calculations have been carried out for examining the curvature
effect of small diameter hexagonal boron nanotubes. The considered
conformations of boron nanotubes are namely armchair (3,3), zigzag (5,0) and
chiral (4,2), and consist of 12, 20, and 56 atoms, respectively. The strain
energy is evaluated in order to examine the curvature effect. It is found that
the strain energy of hexagonal BNT strongly depends upon the radius, whereas
the strain energy of triangular BNTs depends on both radius and chirality.


title: A few cosmological implications of tensor nonlocalities

abstract:
  We consider nonlocal gravity theories that include tensor nonlocalities. We
show that in the cosmological context, the tensor nonlocalities, unlike scalar
ones, generically give rise to growing modes. An explicit example with
quadratic curvature terms is studied in detail. Possible consequences for
recent nonlocal cosmological models proposed in the literature are also
discussed.


abstract:
  In this paper, we consider Hermite and poly-Bernoulli mixed-type polynomials
and investigate the properties of those polynomials which are derived from
umbral calculus. Finally, we give various identities associated with Stirling
numbers, Bernoulli and Frobenius-Euler polynomials of higher order.


title: Compression of animated 3D models using HO-SVD

abstract:
  This work presents an analysis of Higher Order Singular Value Decomposition
(HO-SVD) applied to lossy compression of 3D mesh animations. We describe
strategies for choosing a number of preserved spatial and temporal components
after tensor decomposition. Compression error is measured using three metrics
(MSE, Hausdorff, MSDM). Results are compared with a method based on Principal
Component Analysis (PCA) and presented on a set of animations with typical mesh
deformations.


title:
Calibrating a high-resolution wavefront corrector with a static
  focal-plane camera

abstract:
  We present a method to calibrate a high-resolution wavefront-correcting
device with a single, static camera, located in the focal plane; no moving of
any component is needed. The method is based on a localized diversity and
differential optical transfer functions (dOTF) to compute both the phase and
amplitude in the pupil plane located upstream of the last imaging optics. An
experiment with a spatial light modulator shows that the calibration is
sufficient to robustly operate a focal-plane wavefront sensing algorithm
controlling a wavefront corrector with ~40 000 degrees of freedom. We estimate
that the locations of identical wavefront corrector elements are determined
with a spatial resolution of 0.3% compared to the pupil diameter.


title: Piggyback resistive Micromegas

abstract:
  Piggyback Micromegas consists in a novel readout architecture where the anode
element is made of a resistive layer on a ceramic substrate. The resistive
layer is deposited on the thin ceramic substrate by an industrial process which
provides large dynamic range of resistivity (10$^6$ to
10$^{10}$\,M$\Omega$/square). The particularity of this new structure is that
the active part is entirely dissociated from the read-out element. This gives a
large flexibility on the design of the anode structure and the readout scheme.
Without significant loss, signals are transmitted by capacitive coupling to the
read-out pads. The detector provides high gas gain, good energy resolution and
the resistive layer assures spark protection for the electronics. This assembly
could be combined with modern pixel array electronic ASICs. First tests with
different Piggyback detectors and configurations will be presented. This
structure is adequate for cost effective fabrication and low outgassing
detectors. It was designed to perform in sealed mode and its long term
stability has been extensively studied. In addition perspectives on the future
developments will be evoked.


title: Magnetic fields in neutron stars

abstract:
  This work aims at studying how magnetic fields affect the observational
properties and the long-term evolution of isolated neutron stars, which are the
strongest magnets in the universe. The extreme physical conditions met inside
these astronomical sources complicate their theoretical study, but, thanks to
the increasing wealth of radio and X-ray data, great advances have been made
over the last years. A neutron star is surrounded by magnetized plasma, the
so-called magnetosphere. Modeling its global configuration is important to
understand the observational properties of the most magnetized neutron stars,
magnetars. On the other hand, magnetic fields in the interior are thought to
evolve on long time-scales, from thousands to millions of years. The magnetic
evolution is coupled to the thermal one, which has been the subject of study in
the last decades. An important part of this thesis presents the
state-of-the-art of the magneto-thermal evolution models of neutron stars
during the first million of years, studied by means of detailed simulations.
The numerical code here described is the first one to consistently consider the
coupling of magnetic field and temperature, with the inclusion of both the
Ohmic dissipation and the Hall drift in the crust.


title: A CLT for winding angles of the arms for critical planar percolation

abstract:
  Consider critical percolation in two dimensions. Under the condition that
there are k disjoint alternating black and white arms crossing the annulus
A(l,n), we prove a central limit theorem and variance estimates for the winding
angles of the arms (as n\rightarrow \infty, l fixed). This result confirms a
prediction of Beffara and Nolin (Ann. Probab. 39: 1286--1304, 2011). Using this
theorem, we also get a CLT for the multiple-armed incipient infinite cluster
(IIC) measures.


title: Cosmic Topology : Twenty Years After

abstract:
  What is the shape of the Universe? Is it finite or infinite ? Is space
multi-connected to create ghost images of faraway cosmic sources? After a "dark
age" period, the field of cosmic topology has now become one of the major
concerns in astronomy and cosmology, not only from theorists but also from
observational astronomers. Here I give a personal account of the spectacular
progress in the field since the beginning of the 1990's, when I started to work
in it.


title:
Fermion $N$-representability for prescribed density and paramagnetic
  current density

abstract:
  The $N$-representability problem is the problem of determining whether or not
there exists $N$-particle states with some prescribed property. Here we report
an affirmative solution to the fermion $N$-representability problem when both
the density and paramagnetic current density are prescribed. This problem
arises in current-density functional theory and is a generalization of the
well-studied corresponding problem (only the density prescribed) in density
functional theory. Given any density and paramagnetic current density
satisfying a minimal regularity condition (essentially that a von
Weiz\"acker-like the canonical kinetic energy density is locally integrable),
we prove that there exist a corresponding $N$-particle state. We prove this by
constructing an explicit one-particle reduced density matrix in the form of a
position-space kernel, i.e.\ a function of two continuous position variables.
In order to make minimal assumptions, we also address mathematical subtleties
regarding the diagonal of, and how to rigorously extract paramagnetic current
densities from, one-particle reduced density matrices in kernel form.

categories: math-ph math.MP physics.chem-ph physics.comp-ph quant-ph


title:
Law of large numbers for critical first-passage percolation on the
  triangular lattice

abstract:
  We study the site version of (independent) first-passage percolation on the
triangular lattice $\mathbb{T}$. Denote the passage time of the site $v$ in
$\mathbb{T}$ by $t(v)$, and assume that $P(t(v)=0)=P(t(v)=1)=1/2$. Denote by
$a_{0,n}$ the passage time from $\textbf{0}$ to $(n,0)$, and by $b_{0,n}$ the
passage time from $\textbf{0}$ to the halfplane $\{(x,y):x\geq n\}$. We prove
that there exists a constant $0<\mu<\infty$ such that as $n\rightarrow\infty$,
$a_{0,n}/\log n\rightarrow \mu$ in probability and $b_{0,n}/\log n\rightarrow
\mu/2$ almost surely. This result confirms a prediction of Kesten and Zhang
(Probab. Theory Relat. Fields \textbf{107}: 137--160, 1997). The proof relies
on the existence of the full scaling limit of critical site percolation on
$\mathbb{T}$, established by Camia and Newman.


title:
The sub-mJy radio sky in the Extended Chandra Deep Field South: source
  population

abstract:
  The sub-mJy radio population is a mixture of active systems, that is star
forming galaxies (SFGs) and active galactic nuclei (AGNs). We study a sample of
883 radio sources detected at 1.4 GHz in a deep Very Large Array survey of the
Extended Chandra Deep Field South (E-CDFS) that reaches a best rms sensitivity
of 6 microJy. We have used a simple scheme to disentangle SFGs, radio-quiet
(RQ), and radio-loud (RL) AGNs based on the combination of radio data with
Chandra X-ray data and mid-infrared observations from Spitzer. We find that at
flux densities between about 30 and 100 microJy the radio population is
dominated by SFGs (~60%) and that RQ AGNs become increasingly important over RL
ones below 100 microJy. We also compare the host galaxy properties of the three
classes in terms of morphology, optical colours and stellar masses. Our results
show that both SFG and RQ AGN host galaxies have blue colours and late type
morphology while RL AGNs tend to be hosted in massive red galaxies with early
type morphology. This supports the hypothesis that radio emission in SFGs and
RQ AGNs mainly comes from the same physical process: star formation in the host
galaxy.


title: Reading Stockholm Riots 2013 in social media by text-mining

abstract:
  The riots in Stockholm in May 2013 were an event that reverberated in the
world media for its dimension of violence that had spread through the Swedish
capital. In this study we have investigated the role of social media in
creating media phenomena via text mining and natural language processing. We
have focused on two channels of communication for our analysis: Twitter and
Poloniainfo.se (Forum of Polish community in Sweden). Our preliminary results
show some hot topics driving discussion related mostly to Swedish Police and
Swedish Politics by counting word usage. Typical features for media
intervention are presented. We have built networks of most popular phrases,
clustered by categories (geography, media institution, etc.). Sentiment
analysis shows negative connotation with Police. The aim of this preliminary
exploratory quantitative study was to generate questions and hypotheses, which
we could carefully follow by deeper more qualitative methods.


title: Learning ambiguous functions by neural networks

abstract:
  It is not, in general, possible to have access to all variables that
determine the behavior of a system. Having identified a number of variables
whose values can be accessed, there may still be hidden variables which
influence the dynamics of the system. The result is model ambiguity in the
sense that, for the same (or very similar) input values, different objective
outputs should have been obtained. In addition, the degree of ambiguity may
vary widely across the whole range of input values. Thus, to evaluate the
accuracy of a model it is of utmost importance to create a method to obtain the
degree of reliability of each output result. In this paper we present such a
scheme composed of two coupled artificial neural networks: the first one being
responsible for outputting the predicted value, whereas the other evaluates the
reliability of the output, which is learned from the error values of the first
one. As an illustration, the scheme is applied to a model for tracking slopes
in a straw chamber and to a credit scoring model.


title: Comprehending Quantum Theory from Quantum Fields

abstract:
  At the primary level of reality as described by quantum field theory, a
fundamental particle like an electron represents a stable, discrete,
propagating excited state of its underlying quantum field. QFT also tells us
that the lowest vacuum state as well as the excited states of such a field is
always very active with spontaneous, unpredictable quantum fluctuations. Also
an underlying quantum field is known to be indestructible and immutable
possessing the same value in each element of spacetime comprising the universe.
These characteristics of the primary quantum fields together with the fact that
the quantum fluctuations can be cogently substantiated to be quantum coherent
throughout the universe provide a possible ontology of the quantum theory. In
this picture, the wave function of a quantum particle represents the reality of
the inherent quantum fluctuations at the core of the universe and endows the
particle its counter intuitive quantum behavior.


title:
Real-time analysis of mechanical and electrical resonances with open
  source sound card software

abstract:
  We present an easily reproducible, open-source, sound card based experimental
set-up to support transfer function measurement. Our system is able to
visualize signals of mechanical and electrical resonances and their spectra in
real time. We give a brief description of the system, and show some examples of
electrical and mechanical resonance experiments that are supported by the
system. The theoretical background, experimental set-up, component selection
and digital signal processing are all discussed, and more detailed information
(building instructions, software download) is provided on a dedicated web page
(http://www.noise.inf.u-szeged.hu/edudev/RealTimeAnalysisOfResonances/) The
experimental set-up can support undergraduate and graduate education of
students of physics, physics education and engineering by means of experimental
demonstrations and laboratory exercises. The very low cost, high efficiency and
transparent system provides a scalable experimental environment that can be
easily built in several instances.


title: The fractional parts of Dedekind sums

abstract:
  We show that each rational number $r$, $0\le r<1$, occurs as the fractional
part of a Dedekind sum $S(m,n)$.


title:
Microscopic unitary description of tidal excitations in high-energy
  string-brane collisions

abstract:
  The eikonal operator was originally introduced to describe the effect of
tidal excitations on higher-genus elastic string amplitudes at high energy. In
this paper we provide a precise interpretation for this operator through the
explicit tree-level calculation of generic inelastic transitions between closed
strings as they scatter off a stack of parallel Dp-branes. We perform this
analysis both in the light-cone gauge, using the Green-Schwarz vertex, and in
the covariant formalism, using the Reggeon vertex operator. We also present a
detailed discussion of the high energy behaviour of the covariant string
amplitudes, showing how to take into account the energy factors that enhance
the contribution of the longitudinally polarized massive states in a simple
way.


title: The contact line behaviour of solid-liquid-gas diffuse-interface models

abstract:
  A solid-liquid-gas moving contact line is considered through a
diffuse-interface model with the classical boundary condition of no-slip at the
solid surface. Examination of the asymptotic behaviour as the contact line is
approached shows that the relaxation of the classical model of a sharp
liquid-gas interface, whilst retaining the no-slip condition, resolves the
stress and pressure singularities associated with the moving contact line
problem while the fluid velocity is well defined (not multi-valued). The moving
contact line behaviour is analysed for a general problem relevant for any
density dependent dynamic viscosity and volume viscosity, and for general
microscopic contact angle and double well free-energy forms. Away from the
contact line, analysis of the diffuse-interface model shows that the
Navier--Stokes equations and classical interfacial boundary conditions are
obtained at leading order in the sharp-interface limit, justifying the creeping
flow problem imposed in an intermediate region in the seminal work of Seppecher
[Int. J. Eng. Sci. 34, 977--992 (1996)]. Corrections to Seppecher's work are
given, as an incorrect solution form was originally used.


title: Ultralight Particle Dark Matter

abstract:
  We review the physics case for very weakly coupled ultralight particles
beyond the Standard Model, in particular for axions and axion-like particles
(ALPs): (i) the axionic solution of the strong CP problem and its embedding in
well motivated extensions of the Standard Model; (ii) the possibility that the
cold dark matter in the Universe is comprised of axions and ALPs; (iii) the ALP
explanation of the anomalous transparency of the Universe for TeV photons; and
(iv) the axion or ALP explanation of the anomalous energy loss of white dwarfs.
Moreover, we present an overview of ongoing and near-future laboratory
experiments searching for axions and ALPs: haloscopes, helioscopes, and
light-shining-through-a-wall experiments.


title:
Second order scattering descriptors predict fMRI activity due to visual
  textures

abstract:
  Second layer scattering descriptors are known to provide good classification
performance on natural quasi-stationary processes such as visual textures due
to their sensitivity to higher order moments and continuity with respect to
small deformations. In a functional Magnetic Resonance Imaging (fMRI)
experiment we present visual textures to subjects and evaluate the predictive
power of these descriptors with respect to the predictive power of simple
contour energy - the first scattering layer. We are able to conclude not only
that invariant second layer scattering coefficients better encode voxel
activity, but also that well predicted voxels need not necessarily lie in known
retinotopic regions.


title: Transfinite Asymptotic Dimension

abstract:
  Asymptotic property C for metric spaces was introduced by Dranishnikos as
generalization of finite asymptotic dimension - asdim. It turns out that this
property can be viewed as transfinite extension of asymptotic dimension. The
original definition was given by Radul. We introduce three equivalent
definitions, show that asymptotic property C is closed under products (open
problem stated "Open problems in topology II") and prove some other facts, i.e.
by defining dimension of a family of metric spaces. Some examples of spaces
enjoying countable trasfinite asymptotic dimension are given. We also formulate
open problems and state "omega conjecture", which inspired most part of this
paper.


title:
A Novel Progressive Image Scanning and Reconstruction Scheme based on
  Compressed Sensing and Linear Prediction

abstract:
  Compressed sensing (CS) is an innovative technique allowing to represent
signals through a small number of their linear projections. In this paper we
address the application of CS to the scenario of progressive acquisition of 2D
visual signals in a line-by-line fashion. This is an important setting which
encompasses diverse systems such as flatbed scanners and remote sensing
imagers. The use of CS in such setting raises the problem of reconstructing a
very high number of samples, as are contained in an image, from their linear
projections. Conventional reconstruction algorithms, whose complexity is cubic
in the number of samples, are computationally intractable. In this paper we
develop an iterative reconstruction algorithm that reconstructs an image by
iteratively estimating a row, and correlating adjacent rows by means of linear
prediction. We develop suitable predictors and test the proposed algorithm in
the context of flatbed scanners and remote sensing imaging systems. We show
that this approach can significantly improve the results of separate
reconstruction of each row, providing very good reconstruction quality with
reasonable complexity.


title: On the vacuum stability of SUSY models

abstract:
  The existence of multiple non-equivalent minima of the scalar potential in
SUSY models both raises technical challenges and introduces interesting
physics. The technical challenges are now that one has to find several minima
and evaluate which is the deepest, as well as calculate the tunneling time from
a false vacuum to the true vacuum. We present here studies on the vacuum
stability and color/charge breaking minima in the CMSSM and R parity violating
minima in a B-L extended MSSM.


title: Monomial principalization in the singular setting

abstract:
  We generalize an algorithm by Goward for principalization of monomial ideals
in nonsingular varieties to work on any scheme of finite type over a field. The
normal crossings condition considered by Goward is weakened to the condition
that components of the generating divisors meet as complete intersections. This
leads to a substantial generalization of the notion of monomial scheme; we call
the resulting schemes `c.i. monomial'. We prove that c.i. monomial schemes in
arbitrarily singular varieties can be principalized by a sequence of blow-ups
at codimension 2 c.i. monomial centers.


title:
Analytic Structure of the SCFT Energy Functional of Multicomponent Block
  Copolymers

abstract:
  This paper concerns the analytic structure of the self-consistent field
theory (SCFT) energy functional of multicomponent block copolymer systems which
contain more than two chemically distinct blocks. The SCFT has enjoyed
considered success and wide usage in investigation of the complex phase
behavior of block copolymers. It is well-known that the physical solutions of
the SCFT equations are saddle points, however, the analytic structure of the
SCFT energy functional has received little attention over the years. A recent
work by Fredrickson and collaborators [see the monograph by Fredrickson, The
Equilibrium Theory of Inhomogeneous Polymers, (2006), pp. 203-209] has analysed
the mathematical structure of the field energy functional for polymeric
systems, and clarified the index-1 saddle point nature of the problem produced
by the incompressibility constraint. In this paper, our goals are to draw
further attention to multicomponent block copolymers utilizing the
Hubbard-Stratonovich transformation used by Fredrickson and co-workers. We
first show that the saddle point character of the SCFT energy functional of
multicomponent block copolymer systems may be high index, not only produced by
the incompressibility constraint, but also by the Flory-Huggins interaction
parameters. Our analysis will be beneficial to many theoretical studies, such
as the nucleation theory of ordered phases, the mesoscopic dynamics. As an
application, we then utilize the discovery to develop the gradient-based
iterative schemes to solve the SCFT equations, and illustrate its performance
through several numerical experiments taking ABC star triblock copolymers as an
example.


title:
Diffuse PeV neutrinos from EeV cosmic ray sources: semi-relativistic
  hypernova remnants in star-forming galaxies

abstract:
  We argue that the excess of sub-PeV/PeV neutrinos recently reported by
IceCube could plausibly originate through pion-production processes in the same
sources responsible for cosmic rays (CRs) with energy above the second knee
around $10^{18}\,$eV. The pion production efficiency for escaping CRs that
produce PeV neutrinos is required to be $\gtrsim 0.1$ in such sources. On the
basis of current data, we identify semi-relativistic hypernova remants as
possible sources that satisfy the requirements. By virtue of their fast ejecta,
such objects can accelerate protons to EeV energies, which in turn can interact
with the dense surrounding medium during propagation in their host galaxies to
produce sufficient high-energy neutrinos via proton--proton ($pp$) collisions.
Their accompanying gamma ray flux can remain below the diffuse isotropic gamma
ray background observed by the {\it Fermi} Large Area Telescope (LAT). In order
to test this scenario and discriminate from alternatives, the density of target
protons/nuclei and the residence time of CRs in the interacting region are
crucial uncertainties that need to be clarified. As long as the neutrinos and
EeV CRs originate from the same source class, detection of $\gtrsim 10\,$PeV
neutrinos may be expected within 5-10 years' operation of IceCube. Together
with further observations in the PeV range, the neutrinos can help in revealing
the currently unknown sources of EeV CRs.


title:
Defects, Non-abelian T-duality, and the Fourier-Mukai transform of the
  Ramond-Ramond fields

abstract:
  We construct topological defects generating non-abelian T-duality for
isometry groups acting without isotropy. We find that these defects are given
by line bundles on the correspondence space with curvature which can be
considered as a non-abelian generalization of the curvature of the Poincar\`{e}
bundle. We show that the defect equations of motion encode the non-abelian
T-duality transformation. The Fourier-Mukai transform of the Ramond-Ramond
fields generated by the gauge invariant flux of these defects is studied. We
show that it provides elegant and compact way of computation of the
transformation of the Ramond-Ramond fields under the non-abelian T-duality.


title: Abelianization of BPS Quivers and the Refined Higgs Index

abstract:
  We count Higgs "phase" BPS states of general non-Abelian quiver, possibly
with loops, by mapping the problem to its Abelian, or toric, counterpart and
imposing Weyl invariance later. Precise Higgs index computation is particularly
important for quivers with superpotentials; the Coulomb "phase" index is
recently shown to miss important BPS states, dubbed intrinsic Higgs states or
quiver invariants. We demonstrate how the refined Higgs index is naturally
decomposed to a sum over partitions of the charge. We conjecture, and show in
simple cases, that this decomposition expresses the Higgs index as a sum over a
set of partition-induced Abelian quivers of the same total charge but
generically of smaller rank. Unlike the previous approach inspired by a similar
decomposition of the Coulomb index, our formulae compute the quiver invariants
directly, and thus offer a self-complete routine for counting BPS states.


title:
Progressive Compressed Sensing and Reconstruction of Multidimensional
  Signals Using Hybrid Transform/Prediction Sparsity Model

abstract:
  Compressed sensing (CS) is an innovative technique allowing to represent
signals through a small number of their linear projections. Hence, CS can be
thought of as a natural candidate for acquisition of multidimensional signals,
as the amount of data acquired and processed by conventional sensors could
create problems in terms of computational complexity. In this paper, we propose
a framework for the acquisition and reconstruction of multidimensional
correlated signals. The approach is general and can be applied to D dimensional
signals, even if the algorithms we propose to practically implement such
architectures apply to 2-D and 3-D signals. The proposed architectures employ
iterative local signal reconstruction based on a hybrid transform/prediction
correlation model, coupled with a proper initialization strategy.


abstract:
  This paper presents an algorithm for Monte Carlo fixed-lag smoothing in
state-space models defined by a diffusion process observed through noisy
discrete-time measurements. Based on a particles approximation of the filtering
and smoothing distributions, the method relies on a simulation technique of
conditioned diffusions. The proposed sequential smoother can be applied to
general non linear and multidimensional models, like the ones used in
environmental applications. The smoothing of a turbulent flow in a
high-dimensional context is given as a practical example.


title: The geometric genus of hypersurface singularities

abstract:
  Using the path lattice cohomology we provide a conceptual topological
characterization of the geometric genus for certain complex normal surface
singularities with rational homology sphere links, which is uniformly valid for
all superisolated and Newton non--degenerate hypersurface singularities.


title: Short Homotopically independent loops on surfaces

abstract:
  In this paper, we are interested in short homologically and homotopically
independent loops based at the same point on Riemannian surfaces and metric
graphs.
  First, we show that for every closed Riemannian surface of genus $g \geq 2$
and area normalized to $g$, there are at least $\ceil{\log(2g)+1}$
homotopically independent loops based at the same point of length at most
$C\log(g)$, where $C$ is a universal constant. On the one hand, this result
substantially improves Theorem $5.4.A$ of M. Gromov in \cite{G1}. On the other
hand, it recaptures the result of S. Sabourau on the separating systole in
\cite{SS} and refines his proof.
  Second, we show that for any two integers $b\geq 2$ with $1\leq n\leq b$,
every connected metric graph $\Gamma$ of first Betti number $b$ and of length
$b$ contains at least $n$ homologically independent loops based at the same
point and of length at most $24(\log(b)+n)$. In particular, this result extends
Bollob\`as-Szemer\'edi-Thomason's $\log(b)$ bound on the homological systole to
at least $\log(b)$ homologically independent loops based at the same point.
Moreover, we give examples of graphs where this result is optimal.


title:
Turbulent fluid acceleration generates clusters of gyrotactic
  microorganisms

abstract:
  The motility of microorganisms is often biased by gradients in physical and
chemical properties of their environment, with myriad implications on their
ecology. Here we show that fluid acceleration reorients gyrotactic plankton,
triggering small-scale clustering. We experimentally demonstrate this
phenomenon by studying the distribution of the phytoplankton Chlamydomonas
augustae within a rotating tank and find it to be in good agreement with a new,
generalized model of gyrotaxis. When this model is implemented in a direct
numerical simulation of turbulent flow, we find that fluid acceleration
generates multi-fractal plankton clustering, with faster and more stable cells
producing stronger clustering. By producing accumulations in high-vorticity
regions, this process is fundamen- tally different from clustering by
gravitational acceleration, expanding the range of mechanisms by which
turbulent flows can impact the spatial distribution of active suspensions.


title: Testing honesty of quantum server

abstract:
  Alice, who does not have any sophisticated quantum technology, delegates her
quantum computing to Bob, who has a fully-fledged quantum computer. Can she
check whether the computation Bob performs for her is correct? She cannot
recalculate the result by herself, since she does not have any quantum
computer. A recent experiment with photonic qubits suggests she can. Here, I
explain the basic idea of the result, and recent developments about secure
cloud quantum computing.


title:
Test of the He-McKellar-Wilkens topological phase by atom
  interferometry. Part II: the experiment and its results

abstract:
  In this paper, we describe an experimental test of the He-McKellar-Wilkens
(HMW) topological phase with our lithium atom interferometer. The expected
value of the HMW phase shift in our experiment is small and its measurement was
difficult because of stray phase shifts due to small experimental defects. We
start by describing our setup and we characterize the effects of the electric
and magnetic fields needed to observe the HMW effect. Then, we develop a model
of our interferometer signals including all the defects we have identified.
After various tests of this model, we use it to suppress the largest part of
the stray phase shifts. We thus obtain a series of measurements of the HMW
phase: the results are 31% larger than expected and this discrepancy is
probably due to some limitations of our model.


title:
On the symmetric doubly stochastic matrices that are determined by their
  spectra

abstract:
  A symmetric doubly stochastic matrix A is said to be determined by its
spectra if the only symmetric doubly stochastic matrices that are similar to A
are of the form $P^TAP$ for some permutation matrix P. The problem of
characterizing such matrices is considered here. An almost the same but a more
difficult problem was proposed by [ M. Fang, A note on the inverse eigenvalue
problem for symmetric doubly stochastic matrices, Lin. Alg. Appl., 432 (2010)
2925-2927] as follows: Characterize all n-tuples $\lambda=
(1,\lambda_2,...,\lambda_n)$ such that up to a permutation similarity, there
exists a unique symmetric doubly stochastic matrix with spectrum $\lambda.$ In
this short note, some general results concerning our two problems are first
obtained. Then, we completely solve these two problems for the case n = 3. Some
connections with spectral graph theory are then studied. Finally, concerning
the general case, two open questions are posed and a conjecture is introduced.


title: On the convexity of the entropy along entropic interpolations

abstract:
  Convexity properties of the entropy along displacement interpolations are
crucial in the Lott-Sturm-Villani theory of lower bounded curvature of geodesic
measure spaces. As discrete spaces fail to be geodesic, an alternate analogous
theory is necessary in the discrete setting. Replacing displacement
interpolations by entropic ones allows for developing a rigorous calculus, in
contrast with Otto's informal calculus. When the underlying state space is a
Riemannian manifold, we show that the first and second derivatives of the
entropy as a function of time along entropic interpolations are expressed in
terms of the standard Bakry-\'Emery operators $\Gamma$ and $ \Gamma_2$. On the
other hand, in the discrete setting new operators appear. Our approach is
probabilistic; it relies on the Markov property and time reversal. We
illustrate these calculations by means of Brownian diffusions on manifolds and
random walks on graphs. We also give a new unified proof, covering both the
manifold and graph cases, of a logarithmic Sobolev inequality in connection
with convergence to equilibrium.


title: Bounding the number of remarkable values via Jouanolou's theorem

abstract:
  In this article we bound the number of remarkable values of a polynomial
vector field. The proof is short and based on Jouanolou's theorem about
rational first integrals of planar polynomial derivations. Our bound is given
in term of the size of a Newton polygon associated to the vector field. We
prove that this bound is almost reached.


title:
Rheological and Electrical Transitions in Carbon Nanotube/Epoxy
  Suspensions

abstract:
  The rheological and electrical properties of suspensions of carbon nanotubes
in an uncured epoxy resin were investigated by means of shear rheology and
impedance spectroscopy. It was found that above an onset CNT weight fraction
(0.1 wt %), the steady viscosity increased with CNT loading and presented a
shear thinning behaviour. The concentration dependence of viscosity changed
from a power law to an exponential with increasing shear rate, indicating a
loss of interaction between aggregates and CNT network breakage. The
fluid-to-solidlike and insulator-to-conductor transitions occurred in the same
CNT weight fraction range between 0.5 and 0.6 wt %. The correspondence of these
transitions was explained by the reduction of contact resistance between CNT by
stiffening of the CNT network leading to improved electronic transport.


title: Tilings for Pisot beta numeration

abstract:
  For a (non-unit) Pisot number $\beta$, several collections of tiles are
associated with $\beta$-numeration. This includes an aperiodic and a periodic
one made of Rauzy fractals, a periodic one induced by the natural extension of
the $\beta$-transformation and a Euclidean one made of integral beta-tiles. We
show that all these collections (except possibly the periodic translation of
the central tile) are tilings if one of them is a tiling or, equivalently, the
weak finiteness property (W) holds. We also obtain new results on rational
numbers with purely periodic $\beta$-expansions; in particular, we calculate
$\gamma(\beta)$ for all quadratic $\beta$ with $\beta^2 = a \beta + b$,
$\gcd(a,b) = 1$.


title: On the index of Simon's congruence for piecewise testability

abstract:
  Simon's congruence, denoted \sim_n, relates words having the same subwords of
length up to n. We show that, over a k-letter alphabet, the number of words
modulo \sim_n is in 2^{\Theta(n^{k-1} log n)}.


title: Hawking effect for a toy model of interacting fermions

abstract:
  We consider a toy model of interacting Dirac fermions in a 1+1 dimensional
space time describing the exterior of a star collapsing to a blackhole. In this
situation we give a rigorous proof of the {\em Hawking effect}, namely that
under the associated quantum evolution, an initial vacuum state will converge
when $t\to +\infty$ to a thermal state at Hawking temperature. We establish
this result both for observables falling into the blackhole along null
characteristics, and for static observables. We also consider the case of an
interaction localized near the star boundary, obtaining similar results. We
hence extend to an interacting model previous results of Bachelot and Melnyk,
obtained for free Dirac fields.


title:
New $q-$Hermite polynomials: characterization, operator algebra and
  associated coherent states

abstract:
  This paper addresses a construction of new $q-$Hermite polynomials with a
full characterization of their main properties and corresponding raising and
lowering operator algebra. The three-term recursive relation as well as the
second-order differential equation obeyed by these new polynomials are
explicitly derived. Relevant operator actions, including the eigenvalue problem
of the deformed oscillator and the self-adjointness of the related position and
momentum operators, are investigated and analyzed. The associated coherent
states are constructed and discussed with an explicit resolution of the induced
moment problem.


title: Games and Complexes I: Transformation via Ideals

abstract:
  Placement games are a subclass of combinatorial games which are played on
graphs. We will demonstrate that one can construct simplicial complexes
corresponding to a placement game, and this game could be considered as a game
played on these simplicial complexes. These complexes are constructed using
square-free monomials.


title: Monotone Splines Lasso

abstract:
  We consider the problems of variable selection and estimation in
nonparametric additive regression models for high-dimensional data. In recent
years, several methods have been proposed to model nonlinear relationships when
the number of covariates exceeds the number of observations by using spline
basis functions and group penalties. Nonlinear {\it monotone} effects on the
response play a central role in many situations, in particular in medicine and
biology. We construct the monotone splines lasso (MS-lasso) to select variables
and estimate effects using monotone spline (I-splines). The additive components
in the model are represented by their I-spline basis function expansion and the
component selection becomes that of selecting the groups of coefficients in the
I-spline basis function expansion. We use a recent procedure, called
cooperative lasso, to select sign-coherent groups, that is selecting the groups
with either exclusively non-negative or non-positive coefficients. This leads
to the selection of important covariates that have nonlinear monotone
increasing or decreasing effect on the response. We also introduce an adaptive
version of the MS-lasso which reduces both the bias and the number of false
positive selections considerably. We compare the MS-lasso and the adaptive
MS-lasso with other existing methods for variable selection in high dimensions
by simulation and illustrate the method on two relevant genomic data sets.
Results indicate that the (adaptive) MS-lasso has excellent properties compared
to the other methods both by means of estimation and selection, and can be
recommended for high-dimensional monotone regression.


title: On Low Mass X-ray Binaries and Millisecond Pulsar

abstract:
  The detection, in 1998, of the first Accreting Millisecond Pulsar, started an
exciting season of continuing discoveries in the fashinating field of compact
binary systems harbouring a neutron star. Indeed, in these last three lustres,
thanks to the extraordinary performances of astronomical detectors, on ground
as well as on board of satellites, mainly in the Radio, Optical, X-ray, and
Gamma-ray bands, astrophysicists had the opportunity to thoroughly investigate
the so-called Recycling Scenario: the evolutionary path leading to the
formation of a Millisecond Radio Pulsar. The most intriguing phase is certainly
the spin-up stage during which, because of the accretion of matter and angular
momentum, the neutron star accumulates an extraordinary amount of mechanical
rotational energy, up to one percent of its whole rest-mass energy. These
millisecond spinning neutron stars are truly extreme physical objects: General
and Special Relativity are fully in action, since their surfaces, attaining
speeds close to one fifth of the speed of light, are located just beyond their
Schwartzscild Radius, and electrodynamical forces, caused by the presence of
huge surface magnetic fields of several hundred million Gauss, display their
spectacular properties accelerating electrons up to such energies to promote
pair creation in a cascade process responsible for the emission in Radio and
Gamma-ray. The rotational energy is swiftly converted and released into
electromagnetic power which, in some cases, causes the neutron star to outshine
with a luminosity of one hundred Suns. In this paper I will review some of the
most recent discoveries on (accreting) millisecond pulsars.


title: Discovering the Significance of 5 sigma

abstract:
  We discuss the traditional criterion for discovery in Particle Physics of
requiring a significance corresponding to at least 5 sigma; and whether a more
nuanced approach might be better.


title:
Semantic Measures for the Comparison of Units of Language, Concepts or
  Instances from Text and Knowledge Base Analysis

abstract:
  Semantic measures are widely used today to estimate the strength of the
semantic relationship between elements of various types: units of language
(e.g., words, sentences, documents), concepts or even instances semantically
characterized (e.g., diseases, genes, geographical locations). Semantic
measures play an important role to compare such elements according to semantic
proxies: texts and knowledge representations, which support their meaning or
describe their nature. Semantic measures are therefore essential for designing
intelligent agents which will for example take advantage of semantic analysis
to mimic human ability to compare abstract or concrete objects. This paper
proposes a comprehensive survey of the broad notion of semantic measure for the
comparison of units of language, concepts or instances based on semantic proxy
analyses. Semantic measures generalize the well-known notions of semantic
similarity, semantic relatedness and semantic distance, which have been
extensively studied by various communities over the last decades (e.g.,
Cognitive Sciences, Linguistics, and Artificial Intelligence to mention a few).


title: H\"{o}lder and Minkowski Type Inequalities with Alternating Signs

abstract:
  We obtain new inequalities with alternating signs of H\"{o}lder and Minkowski
type.


title: The Precision IceCube Next Generation Upgrade

abstract:
  The IceCube Neutrino Observatory, completed in December 2010 and located at
the geographic South Pole, is the largest neutrino telescope in the world.
IceCube includes the more densely instrumented DeepCore subarray, which
increases IceCube's sensitivity at neutrino energies down to 10 GeV. DeepCore
has recently demonstrated sensitivity to muon neutrino disappearance from
atmospheric neutrino oscillation. A further extension is under consideration,
the Precision IceCube Next Generation Upgrade (PINGU) which would lower the
energy threshold below about 10 GeV. In particular, PINGU would be sensitive to
the effects of the neutrino mass hierarchy, which is one of the outstanding
questions in particle physics. Preliminary feasibility studies indicate that
PINGU can make a high significance determination of the mass hierarchy within a
few years of construction.

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


title: Local density dependent potential for compressible mesoparticles

abstract:
  We focus on finding a coarse grained description able to reproduce the
thermodynamic behavior of a molecular system by using mesoparticles
representing several molecules. Interactions between mesoparticles are modelled
by an interparticle potential, and an additional internal equation of state is
used to account for the thermic contribution of coarse grained internal degrees
of freedom. Moreover, as strong non-equilibrium situations over a wide range of
pressure and density are targeted, the internal compressibility of these
mesoparticles has to be considered. This is done by introducing a dependence of
the potential on the local environment of the mesoparticles, either by defining
a spherical local density or by means of a Voronoi tessellation. As an example,
a local density dependent potential is fitted to reproduce the Hugoniot curve
of a model of nitromethane, where each mesoparticle represents one thousand
molecules.


title:
Difference algebraic relations among solutions of linear differential
  equations

abstract:
  We extend and apply the Galois theory of linear differential equations
equipped with the action of an endomorphism. The Galois groups in this Galois
theory are difference algebraic groups and we use structure theorems for these
groups to characterize the possible difference algebraic relations among
solutions of linear differential equations. This yields tools to show that
certain special functions are difference transcendent. One of our main results
is a characterization of discrete integrability of linear differential
equations with almost simple usual Galois group, based on a structure theorem
for the Zariski dense difference algebraic subgroups of almost simple algebraic
groups, which is a schematic version, in characteristic zero, of a result due
to Z. Chatzidakis, E. Hrushovski and Y. Peterzil.


title: Singularity avoidance in the hybrid quantization of the Gowdy model

abstract:
  One of the most remarkable phenomena in Loop Quantum Cosmology is that, at
least for homogeneous cosmological models, the Big Bang is replaced with a Big
Bounce that connects our universe with a previous branch without passing
through a cosmological singularity. The goal of this work is to study the
existence of singularities in Loop Quantum Cosmology including inhomogeneities
and check whether the behavior obtained in the purely homogeneous setting
continues to be valid. With this aim, we focus our attention on the three-torus
Gowdy cosmologies with linearly polarized gravitational waves and use effective
dynamics to carry out the analysis. For this model, we prove that all the
potential cosmological singularities are avoided, generalizing the results
about resolution of singularities to this scenario with inhomogeneities. We
also demonstrate that, if a bounce in the (Bianchi background) volume occurs,
the inhomogeneities increase the value of this volume at the bounce with
respect to its counterpart in the homogeneous case.


title: Long-lived heteronuclear spin-singlet states

abstract:
  We report observation of long-lived spin-singlet states in a 13C-1H spin pair
at zero magnetic field. In 13C-labeled formic acid, we observe spin-singlet
lifetimes as long as 37 seconds, about a factor of three longer than the T1
lifetime of dipole polarization in the triplet state. We also observe that the
lifetime of the singlet-triplet coherence, T2, is longer than T1. Moreover, we
demonstrate that this singlet states formed by spins of a heteronucleus and a
1H nucleus, can exhibit longer lifetimes than the respective triplet states in
systems consisting of more than two nuclear spins. Although long-lived
homonuclear spin-singlet states have been extensively studied, this is the
first experimental observation of analogous spin-singlets consisting of a
heteronucleus and a proton.


title: Spectroscopic imaging of a dilute cell suspension

abstract:
  A rigorous homogenization theory is derived to describe the effective
admittivity of cell suspensions. A new formula is reported for dilute cases
that gives the frequency-dependent effective admittivity with respect to the
membrane polarization. Different microstructures are shown to be
distinguishable via spectroscopic measurements of the overall admittivity using
the spectral properties of the membrane polarization. The Debye relaxation
times associated with the membrane polarization tensor are shown to be able to
give the microscopic structure of the medium. A natural measure of the
admittivity anisotropy is introduced and its dependence on the frequency of
applied current is derived. A Maxwell-Wagner-Fricke formula is given for
concentric circular cells, and the results can be extended to the random cases.
A randomly deformed periodic medium is also considered and a new formula is
derived for the overall admittivity of a dilute suspension of randomly deformed
cells.


title: Charge Distribution about an Ionizing Electron Track in Liquid Helium

abstract:
  The dependence on an applied electric field of the ionization current
produced by an energetic electron stopped in liquid helium can be used to
determine the spatial distribution of secondary electrons with respect to their
geminate partners. An analytic expression relating the current and distribution
is derived. The distribution is found to be non-Gaussian with a long tail at
larger distances.

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


title:
The Bethe Free Energy Allows to Compute the Conditional Entropy of
  Graphical Code Instances. A Proof from the Polymer Expansion

abstract:
  The main objective of this paper is to explore the precise relationship
between the Bethe free energy (or entropy) and the Shannon conditional entropy
of graphical error correcting codes. The main result shows that the Bethe free
energy associated with a low-density parity-check code used over a binary
symmetric channel in a large noise regime is, with high probability,
asymptotically exact as the block length grows. To arrive at this result we
develop new techniques for rather general graphical models based on the loop
sum as a starting point and the polymer expansion from statistical mechanics.
The true free energy is computed as a series expansion containing the Bethe
free energy as its zero-th order term plus a series of corrections. It is
easily seen that convergence criteria for such expansions are satisfied for
general high-temperature models. We apply these general results to ensembles of
low-density generator-matrix and parity-check codes. While the application to
generator-matrix codes follows standard "high temperature" methods, the case of
parity-check codes requires non-trivial new ideas because the hard constraints
correspond to a zero-temperature regime. Nevertheless one can combine the
polymer expansion with expander and counting arguments to show that the
difference between the true and Bethe free energies vanishes with high
probability in the large block


title: What do kets represent?

abstract:
  It is usually assumed that a ket represents the state of an actually existing
particle. But one can show there is no evidence for particles. The
particle-like properties of mass, spin and charge, as well as particle-like
trajectories, the photoelectric effect, and localized effects from spread-out
wave functions can be explained using quantum mechanics alone. It is therefore
proposed instead that kets represent particle-like solutions to a
pre-representational linear partial differential equation which has Poincar\'e
and internal symmetries. This equation underlies the completely
representational character, including mass, spin, charge, internal symmetries,
and symmetric and antisymmetric statistics, of current quantum mechanics.


title: Renormalization in supersymmetric models

abstract:
  There are reasons to believe that the Standard Model is only an effective
theory, with new Physics lying beyond it. Supersymmetric extensions are one
possibility: they address some of the Standard Model's shortcomings, such as
the instability of the Higgs boson mass under radiative corrections. In this
thesis, some topics related to the renormalization of supersymmetric models are
analyzed. One of them is the automatic computation of the Lagrangian and the
renormalization group equations of these models, which is a hard and
error-prone process if carried out by hand. The generic renormalization group
equations themselves are extended so as to include those models which have more
than a single abelian gauge factor group. Such situations can occur in grand
unified theories, for example. For a wide range of SO(10)-inspired
supersymmetric models, we also show that the renormalization group imprints on
sparticle masses some information on the higher energies behavior of the
models. Finally, in some cases these theories introduce charged lepton flavor
violating interactions, which can change the ratio $\Gamma\left(K\rightarrow
e\nu\right)/\Gamma\left(K\rightarrow\mu\nu\right)$. In light of experimental
bounds on other observables, our analysis shows that any change over the
Standard Model prediction must be smaller than the current experimental
sensitivity on this observable.


title: Spectral Clustering for Divide-and-Conquer Graph Matching

abstract:
  We present a parallelized bijective graph matching algorithm that leverages
seeds and is designed to match very large graphs. Our algorithm combines
spectral graph embedding with existing state-of-the-art seeded graph matching
procedures. We justify our approach by proving that modestly correlated, large
stochastic block model random graphs are correctly matched utilizing very few
seeds through our divide-and-conquer procedure. We also demonstrate the
effectiveness of our approach in matching very large graphs in simulated and
real data examples, showing up to a factor of 8 improvement in runtime with
minimal sacrifice in accuracy.


title: Laser Theory for Optomechanics: Limit Cycles in the Quantum Regime

abstract:
  Optomechanical systems can exhibit self-sustained limit cycles where the
quantum state of the mechanical resonator possesses nonclassical
characteristics such as a strongly negative Wigner density, as was shown
recently in a numerical study by Qian et al. [Physical Review Letters, 109,
253601 (2012)]. Here we derive a Fokker-Planck equation describing mechanical
limit cycles in the quantum regime which correctly reproduces the numerically
observed nonclassical features. The derivation starts from the standard
optomechanical master equation, and is based on techniques borrowed from the
laser theory due to Haake's and Lewenstein. We compare our analytical model
with numerical solutions of the master equation based on Monte-Carlo
simulations, and find very good agreement over a wide and so far unexplored
regime of system parameters. As one main conclusion, we predict negative Wigner
functions to be observable even for surprisingly classical parameters, i.e.
outside the single-photon strong coupling regime, for strong cavity drive, and
rather large limit cycle amplitudes. The general approach taken here provides a
natural starting point for further studies of quantum effects in optomechanics.


title:
Calculation of mean spectral density for statistically uniform tree-like
  random models

abstract:
  For random matrices with tree-like structure there exists a recursive
relation for the local Green functions whose solution permits to find directly
many important quantities in the limit of infinite matrix dimensions. The
purpose of this note is to investigate and compare expressions for the spectral
density of random regular graphs, based on easy approximations for real
solutions of the recursive relation valid for trees with large coordination
number. The obtained formulas are in a good agreement with the results of
numerical calculations even for small coordination number.


title:
Free energy calculations from adaptive molecular dynamics simulations
  with adiabatic reweighting

abstract:
  We propose an adiabatic reweighting algorithm for computing the free energy
along an external parameter from adaptive molecular dynamics simulations. The
adaptive bias is estimated using Bayes identity and information from all the
sampled configurations. We apply the algorithm to a structural transition in a
cluster and to the migration of a crystalline defect along a reaction
coordinate. Compared to standard adaptive molecular dynamics, we observe an
acceleration of convergence. With the aid of the algorithm, it is also possible
to iteratively construct the free energy along the reaction coordinate without
having to differentiate the gradient of the reaction coordinate or any biasing
potential.


title:
Correlation evolution in dilute Bose-Einstein condensates after quantum
  quenches

abstract:
  The universal forms of quantum density and phase correlations after an
interaction quench are found for dilute 1d, 2d, and 3d condensates. A
Bogoliubov approach in a local density aproximation is used. We obtain compact
expressions for the most visible effects. Our results show how loss of phase
coherence and antibunching are built up after the quench by quantum
fluctuations. We demonstrate further that the density correlations can be
observed even with imaging resolution much worse than healing length. This
indicates that the direct measurement of counterpropagating atom pairs in situ
in a continuum system is realistic. The conditions in contemporary 1d
experiments are especially favorable for the correlation wave observations.


title:
Towards the Andr\'e-Oort conjecture for mixed Shimura varieties: the
  Ax-Lindemann theorem and lower bounds for Galois orbits of special points

abstract:
  We prove in this paper the Ax-Lindemann-Weierstrass theorem for all mixed
Shimura varieties and discuss the lower bounds for Galois orbits of special
points of mixed Shimura varieties. In particular we reprove a result of
Silverberg in a different approach. Then combining these results we prove the
Andr\'e-Oort conjecture for any mixed Shimura variety whose pure part is a
subvariety of A_6^n.


title:
A counterexample concerning quantifier elimination in quasianalytic
  structures

abstract:
  This paper is a revised version of our preprints IMUJ Preprint 2012/04 and
RAAG Preprint 343 from May 2012. It provides an example of a quasianalytic
structure which, unlike the classical analytic structure, does not admit
quantifier elimination in the language of restricted quasianalytic functions
augmented by the reciprocal function. It also demonstrates that Lojasiewicz's
theorem that every subanalytic curve is semianalytic is no longer true in
quasianalytic structures. Our construction applies rectilinearization of terms,
established in our earlier papers, as well as some theorems on power
substitution for Denjoy-Carleman classes and on non-extendability of
quasianalytic function germs. The last result relies on Grothendieck's
factorization and open mapping theorems for (LF)-spaces.


title:
Novel measures based on the Kolmogorov complexity for use in complex
  system behavior studies and time series analysis

abstract:
  We have proposed novel measures based on the Kolmogorov complexity for use in
complex system behavior studies and time series analysis. We have considered
background of the Kolmogorov complexity and also we have discussed meaning of
the physical as well as other complexities. To get better insights into the
complexity of complex systems and time series analysis we have introduced the
three novel measures based on the Kolmogorov complexity: (i) the Kolmogorov
complexity spectrum, (ii) the Kolmogorov complexity spectrum highest value and
(iii) the overall Kolmogorov complexity. The characteristics of these measures
have been tested using a generalized logistic equation. Finally, the proposed
measures have been applied on different time series originating from: the model
output (the biochemical substance exchange in a multi-cell system), four
different geophysical phenomena (dynamics of: river flow, long term
precipitation, indoor 222Rn concentration and UV radiation dose) and economy
(stock prices dynamics). Results which are obtained offer deeper insights into
complexity of the system dynamics behavior and time series analysis when the
proposed complexity measures are applied.


title: Relaxation limit for Aw-Rascle system

abstract:
  In this paper we apply the Invariant Regions Theory and the Compensated
Compactness Method, to study the singular limit of stiff relaxation and domain
diffusion for the Cauchy problem of Aw-Rascle system.


title: Bit flipping and time to recover

abstract:
  We call `bits' a sequence of devices indexed by positive integers, where
every device can be in two states: $0$ (idle) and $1$ (active). Start from the
`ground state' of the system when all bits are in $0$-state. In our first
Binary Flipping (BF) model, the evolution of the system is the following: at
each time step choose one bit from a given distribution $\mathcal{P}$ on the
integers independently of anything else, then flip the state of this bit to the
opposite. In our second Damaged Bits (DB) model a `damaged' state is added:
each selected idling bit changes to active, but selecting an active bit changes
its state to damaged in which it then stays forever.
  In both models we analyse the recurrence of the system's ground state when no
bits are active. We present sufficient conditions for both BF and DB models to
show recurrent or transient behaviour, depending on the properties of
$\mathcal{P}$. We provide a bound for fractional moments of the return time to
the ground state for the BF model, and prove a Central Limit Theorem for the
number of active bits for both models.


title: The electronic structure of the high-symmetry perovskite iridate Ba2IrO4

abstract:
  We report angle-resolved photoemission (ARPES) measurements, density
functional and model tight-binding calculations on Ba$_2$IrO$_4$ (Ba-214), an
antiferromagnetic ($T_N=230$ K) insulator. Ba-214 does not exhibit the
rotational distortion of the IrO$_6$ octahedra that is present in its sister
compound Sr$_2$IrO$_4$ (Sr-214), and is therefore an attractive reference
material to study the electronic structure of layered iridates. We find that
the band structures of Ba-214 and Sr-214 are qualitatively similar, hinting at
the predominant role of the spin-orbit interaction in these materials.
Temperature-dependent ARPES data show that the energy gap persists well above
$T_N$, and favour a Mott over a Slater scenario for this compound.


title: FPGA based data acquisition system for COMPASS experiment

abstract:
  This paper discusses the present data acquisition system (DAQ) of the COMPASS
experiment at CERN and presents development of a new DAQ. The new DAQ must
preserve present data format and be able to communicate with FPGA cards. Parts
of the new DAQ are based on state machines and they are implemented in C++ with
usage of the QT framework, the DIM library, and the IPBus technology. Prototype
of the system is prepared and communication through DIM between parts was
tested. An implementation of the IPBus technology was prepared and tested. The
new DAQ proved to be able to fulfill requirements.


title: Cocompactly cubulated graph manifolds

abstract:
  Let M be a graph manifold. We show that \pi_1M is the fundamental group of a
compact nonpositively curved cube complex if and only if M is chargeless. We
also prove that in that case \pi_1M is virtually compact special.


title:
The globally hyperbolic metric splitting for non-smooth wave-type
  space-times

abstract:
  We investigate a generalization of the so-called metric splitting of globally
hyperbolic space-times to non-smooth Lorentzian manifolds and show the
existence of this metric splitting for a class of wave-type space-times. Our
approach is based on smooth approximations of non-smooth space-times by
families (or sequences) of globally hyperbolic space-times. In the same setting
we indicate as an application the extension of a previous result on the Cauchy
problem for the wave equation.


title:
The supernova CSS121015:004244+132827: a clue for understanding
  super-luminous supernovae

abstract:
  We present optical photometry and spectra of the super luminous type II/IIn
supernova CSS121015:004244+132827 (z=0.2868) spanning epochs from -30 days
(rest frame) to more than 200 days after maximum. CSS121015 is one of the more
luminous supernova ever found and one of the best observed. The photometric
evolution is characterized by a relatively fast rise to maximum (~40 days in
the SN rest frame), and by a linear post-maximum decline. The light curve shows
no sign of a break to an exponential tail. A broad Halpha is first detected at
~ +40 days (rest-frame). Narrow, barely-resolved Balmer and [O III] 5007 A
lines, with decreasing strength, are visible along the entire spectral
evolution. The spectra are very similar to other super luminous supernovae
(SLSNe) with hydrogen in their spectrum, and also to SN 2005gj, sometimes
considered a type Ia interacting with H-rich CSM. The spectra are also similar
to a subsample of H-deficient SLSNe. We propose that the properties of
CSS121015 are consistent with the interaction of the ejecta with a massive,
extended, opaque shell, lost by the progenitor decades before the final
explosion, although a magnetar powered model cannot be excluded. Based on the
similarity of CSS121015 with other SLSNe (with and without H), we suggest that
the shocked-shell scenario should be seriously considered as a plausible model
for both types of SLSN.


title: Properties of subentropy

abstract:
  Subentropy is an entropy-like quantity that arises in quantum information
theory; for example, it provides a tight lower bound on the accessible
information for pure state ensembles, dual to the von Neumann entropy upper
bound in Holevo's theorem. Here we establish a series of properties of
subentropy, paralleling the well-developed analogous theory for von Neumann
entropy. Further, we show that subentropy is a lower bound for min-entropy. We
introduce a notion of conditional subentropy and show that it can be used to
provide an upper bound for the guessing probability of any classical-quantum
state of two qubits; we conjecture that the bound applies also in higher
dimensions. Finally we give an operational interpretation of subentropy within
classical information theory.


title: Conductivity of Si(111) - 7 x 7: the role of a single atomic step

abstract:
  The Si(111) - 7 x 7 surface is one of the most interesting semiconductor
surfaces because of its complex reconstruction and fascinating electronic
properties. While it is known that the Si - 7 x 7 is a conducting surface, the
exact surface conductivity has eluded consensus for decades as measured values
differ by 7 orders of magnitude. Here we report a combined STM and transport
measurement with ultra-high spatial resolution and minimal interaction with the
sample, and quantitatively determine the intrinsic conductivity of the Si - 7 x
7 surface. This is made possible by the capability of measuring transport
properties with or without a single atomic step between the measuring probes:
we found that even a single step can reduce the surface conductivity by two
orders of magnitude. Our first principles quantum transport calculations
confirm and lend insight to the experimental observation.


title:
The Generalized Degrees of Freedom of the Interference Relay Channel
  with Strong Interference

abstract:
  The interference relay channel (IRC) under strong interference is considered.
A high-signal-to-noise ratio (SNR) generalized degrees of freedom (GDoF)
characterization of the capacity is obtained. To this end, a new GDoF upper
bound is derived based on a genie-aided approach. The achievability of the GDoF
is based on cooperative interference neutralization. It turns out that the
relay increases the GDoF even if the relay-destination link is weak. Moreover,
in contrast to the standard interference channel, the GDoF is not a
monotonically increasing function of the interference strength in the strong
interference regime.


title:
Driven isotropic Heisenberg spin chain with arbitrary boundary twisting
  angle: exact results

abstract:
  We consider an open isotropic Heisenberg quantum spin chain, coupled at the
ends to boundary reservoirs polarized in different directions, which sets up a
twisting gradient across the chain. Using a matrix product ansatz, we calculate
the exact magnetization profiles and magnetization currents in the
nonequilibrium steady steady state of a chain with N sites. The magnetization
profiles are harmonic functions with a frequency proportional to the twisting
angle {\theta}. The currents of the magnetization components lying in the
twisting plane and in the orthogonal direction behave qualitatively
differently: In-plane steady state currents scale as 1/N^2 for fixed and
sufficiently large boundary coupling, and vanish as the coupling increases,
while the transversal current increases with the coupling and saturates to
2{\theta}/N.

categories: cond-mat.stat-mech math-ph math.MP quant-ph


title: A note on monadic datalog on unranked trees

abstract:
  In the article 'Recursive queries on trees and data trees' (ICDT'13),
Abiteboul et al., asked whether the containment problem for monadic datalog
over unordered unranked labeled trees using the child relation and the
descendant relation is decidable. This note gives a positive answer to this
question, as well as an overview of the relative expressive power of monadic
datalog on various representations of unranked trees.


title: $p$-Laplace equations with singular weights

abstract:
  We study a class of $p$-Laplacian Dirichlet problems with weights that are
possibly singular on the boundary of the domain, and obtain nontrivial
solutions using Morse theory. In the absence of a direct sum decomposition, we
use a cohomological local splitting to get an estimate of the critical groups.


title:
A comment on the construction of the maximal globally hyperbolic Cauchy
  development

abstract:
  Under mild assumptions, we remove all traces of the axiom of choice from the
construction of the maximal globally hyperbolic Cauchy development in general
relativity. The construction relies on the notion of direct union manifolds,
which we review. The construction given is very general: any physical theory
with a suitable geometric representation (in particular all classical fields),
and such that a strong notion of "local existence and uniqueness" of solutions
for the corresponding initial value problem is available, is amenable to the
same treatment.


title: Reply to the Comment "Past of a quantum particle and weak measurement"

abstract:
  Misinterpretation in the preceding Comment of my recent analysis of the past
of a photon is corrected. There is nothing in this analysis which is "contrary
to the usual quantum expectations" but, nevertheless, it does provide "further
understanding and interpretation of the system considered". In particular, it
teaches us that the naive common sense argument frequently used in the
literature including the Comment has to be abandoned.


title: Gravitational blueshift from a collapsing object

abstract:
  We discuss a counterintuitive phenomenon of classical general relativity, in
which a significant fraction of the radiation emitted by a collapsing object
and detected by a distant observer may be blueshifted rather than redshifted.
The key-point is that when the radiation propagates inside the collapsing body
it is blueshifted, and this time interval may be sufficiently long for the
effect to be larger than the later redshift due to the propagation in the
vacuum exterior, from the surface of the body to the distant observer.
Unfortunately, the phenomenon can unlikely have direct observational
implications, but it is interesting by itself as a pure relativistic effect.


title: Rotating D0-branes and consistent truncations of supergravity

abstract:
  The fluctuations around the D0-brane near-horizon geometry are described by
two-dimensional SO(9) gauged maximal supergravity. We work out the U(1)^4
truncation of this theory whose scalar sector consists of five dilaton and four
axion fields. We construct the full non-linear Kaluza-Klein ansatz for the
embedding of the dilaton sector into type IIA supergravity. This yields a
consistent truncation around a geometry which is the warped product of a
two-dimensional domain wall and the sphere S^8. As an application, we consider
the solutions corresponding to rotating D0-branes which in the near-horizon
limit approach AdS2xM8 geometries, and discuss their thermodynamical
properties. More generally, we study the appearance of such solutions in the
presence of non-vanishing axion fields.


title: The regularity of geodesics in impulsive pp-waves

abstract:
  We consider the geodesic equation in impulsive pp-wave space-times in Rosen
form, where the metric is of Lipschitz regularity. We prove that the geodesics
(in the sense of Caratheodory) are actually continuously differentiable,
thereby rigorously justifying the $C^1$-matching procedure which has been used
in the literature to explicitly derive the geodesics in space-times of this
form.


title: On Legendre's, Brocard's, Andrica's, and Oppermann's Conjectures

abstract:
  Let $n\in\mathbb{Z}^+$. Is it true that every sequence of $n$ consecutive
integers greater than $n^2$ and smaller than $(n+1)^2$ contains at least one
prime number? In this paper we show that this is actually the case for every $n
\leq 1,193,806,023$. In addition, we prove that a positive answer to the
previous question for all $n$ would imply Legendre's, Brocard's, Andrica's, and
Oppermann's conjectures, as well as the assumption that for every $n$ there is
always a prime number in the interval $[n,n+2\lfloor\sqrt{n}\rfloor-1]$.


title: Matrix computations for the dynamics of fermionic systems

abstract:
  In a series of recent papers we have shown how the dynamical behavior of
certain classical systems can be analyzed using operators evolving according to
Heisenberg-like equations of motions. In particular, we have shown that raising
and lowering operators play a relevant role in this analysis. The technical
problem of our approach stands in the difficulty of solving the equations of
motion, which are, first of all, {\em operator-valued} and, secondly, quite
often nonlinear. In this paper we construct a general procedure which
significantly simplifies the treatment for those systems which can be described
in terms of fermionic operators. The proposed procedure allows to get an
analytic solution, both for quadratic and for more general hamiltonians.


title: M-strings, Elliptic Genera and N=4 String Amplitudes

abstract:
  We study mass-deformed N=2 gauge theories from various points of view. Their
partition functions can be computed via three dual approaches: firstly,
(p,q)-brane webs in type II string theory using Nekrasov's instanton calculus,
secondly, the (refined) topological string using the topological vertex
formalism and thirdly, M theory via the elliptic genus of certain M-strings
configurations. We argue for a large class of theories that these approaches
yield the same gauge theory partition function which we study in detail. To
make their modular properties more tangible, we consider a fourth approach by
connecting the partition function to the equivariant elliptic genus of R^4
through a (singular) theta-transform. This form appears naturally as a specific
class of one-loop scattering amplitudes in type II string theory on T^2, which
we calculate explicitly.


title:
Aharonov-Bohm phase-driven resonant tunneling of interacting electrons
  in magnetopolaronic Majorana-Resonant-Level Model

abstract:
  The magnetopolaronic generalization of a Majorana-resonant-level (-MRL) model
is considered for a single-level vibrating quantum dot symmetrically coupled to
two half-infinite $g=1/2$- Tomonaga-Luttinger liquid (-TLL) leads at the
Toulouse point. At the resonance by gate voltage the exact solution for the
effective transmission coefficient is obtained in the whole range of
magnetopolaronic coupling constant values. The obtained exact solution exists
due to special Majorana-like symmetry of tunnel Hamiltonian and gives rise to
nontrivial interference between different virtual vibronic channels of resonant
tunneling with different fixed Aharonov-Bohm phases. This fact leads to a novel
topologically nontrivial type of resonant Andreev-like magnetopolaronic
tunneling in the system. As the result, in the zero-temperature limit, it is
impossible to compensate the magnetopolaronic blockade in magnetopolaronic
MRL-model by means of bias voltage, if vibron energy is the smallest (but
nonzero) energy parameter in the system.


title: Games and Complexes II: Weight Games and Kruskal-Katona Type Bounds

abstract:
  A strong placement game $G$ played on a board $B$ is equivalent to a
simplicial complex $\Delta_{G,B}$. We look at weight games, a subclass of
strong placement games, and introduce upper bounds on the number of positions
with $i$ pieces in $G$, or equivalently the number of faces with $i$ vertices
in $\Delta_{G,B}$, which are reminiscent of the Kruskal-Katona bounds.


title:
The Relevance of Proofs of the Rationality of Probability Theory to
  Automated Reasoning and Cognitive Models

abstract:
  A number of well-known theorems, such as Cox's theorem and de Finetti's
theorem. prove that any model of reasoning with uncertain information that
satisfies specified conditions of "rationality" must satisfy the axioms of
probability theory. I argue here that these theorems do not in themselves
demonstrate that probabilistic models are in fact suitable for any specific
task in automated reasoning or plausible for cognitive models. First, the
theorems only establish that there exists some probabilistic model; they do not
establish that there exists a useful probabilistic model, i.e. one with a
tractably small number of numerical parameters and a large number of
independence assumptions. Second, there are in general many different
probabilistic models for a given situation, many of which may be far more
irrational, in the usual sense of the term, than a model that violates the
axioms of probability theory. I illustrate this second point with an extended
examples of two tasks of induction, of a similar structure, where the
reasonable probabilistic models are very different.


title: A note on permutation twist defects in topological bilayer phases

abstract:
  We present a mathematical derivation of some of the most important physical
quantities arising in topological bilayer systems with permutation twist
defects as introduced by Barkeshli et al. in cond-mat/1208.4834. A crucial tool
is the theory of permutation equivariant modular functors developed by Barmeier
et al. in math.CT/0812.0986 and math.QA/1004.1825.


title: Unfolding the double shuffle structure of q-multiple zeta values

abstract:
  We exhibit the double q-shuffle structure for the qMZVs recently introduced
by Y. Ohno, J. Okuda and W. Zudilin.