title: Equilateral L-Contact Graphs

abstract:
  We consider {\em L-graphs}, that is contact graphs of axis-aligned L-shapes
in the plane, all with the same rotation. We provide several characterizations
of L-graphs, drawing connections to Schnyder realizers and canonical orders of
maximally planar graphs. We show that every contact system of L's can always be
converted to an equivalent one with equilateral L's. This can be used to show a
stronger version of a result of Thomassen, namely, that every planar graph can
be represented as a contact system of square-based cuboids.
  We also study a slightly more restricted version of equilateral L-contact
systems and show that these are equivalent to homothetic triangle contact
representations of maximally planar graphs. We believe that this new
interpretation of the problem might allow for efficient algorithms to find
homothetic triangle contact representations, that do not use Schramm's monster
packing theorem.


title: Large-Margin Metric Learning for Partitioning Problems

abstract:
  In this paper, we consider unsupervised partitioning problems, such as
clustering, image segmentation, video segmentation and other change-point
detection problems. We focus on partitioning problems based explicitly or
implicitly on the minimization of Euclidean distortions, which include
mean-based change-point detection, K-means, spectral clustering and normalized
cuts. Our main goal is to learn a Mahalanobis metric for these unsupervised
problems, leading to feature weighting and/or selection. This is done in a
supervised way by assuming the availability of several potentially partially
labelled datasets that share the same metric. We cast the metric learning
problem as a large-margin structured prediction problem, with proper definition
of regularizers and losses, leading to a convex optimization problem which can
be solved efficiently with iterative techniques. We provide experiments where
we show how learning the metric may significantly improve the partitioning
performance in synthetic examples, bioinformatics, video segmentation and image
segmentation problems.


title:
Crystal field with Wannier functions: Application to rare-earth
  aluminates

abstract:
  A method to calculate the crystal field parameters {\it ab initio} is
proposed and applied to trivalent rare earth impurities in yttrium aluminate
and to Tb$^{3+}$ ion in TbAlO$_3$. To determine crystal field parameters local
Hamiltonian expressed in basis of Wannier functions is expanded in a series of
spherical tensor operators. Wannier functions are obtained by transforming the
Bloch functions calculated using the density functional theory based program.
The results show that the crystal field is continuously decreasing as the
number of $4f$ electrons increases and that the hybridization of $4f$ states
with the states of oxygen ligands is important. Theory is confronted with
experiment for Nd$^{3+}$ and Er$^{3+}$ ions in YAlO$_3$ and for Tb$^{3+}$ ion
in TbAlO$_3$ and a fair agreement is found.


title: Quantile-based classifiers

abstract:
  Quantile classifiers for potentially high-dimensional data are defined by
classifying an observation according to a sum of appropriately weighted
component-wise distances of the components of the observation to the
within-class quantiles. An optimal percentage for the quantiles can be chosen
by minimizing the misclassification error in the training sample.
  It is shown that this is consistent, for $n \to \infty$, for the
classification rule with asymptotically optimal quantile, and that, under some
assumptions, for $p\to\infty$ the probability of correct classification
converges to one. The role of skewness of the involved variables is discussed,
which leads to an improved classifier.
  The optimal quantile classifier performs very well in a comprehensive
simulation study and a real data set from chemistry (classification of
bioaerosols) compared to nine other classifiers, including the support vector
machine and the recently proposed median-based classifier (Hall et al., 2009),
which inspired the quantile classifier.


title:
Inhomogeneous shear of orthotropic incompressible non-linearly elastic
  solids: singular solutions and biomechanical interpretation

abstract:
  We present a detailed study of rectilinear shear deformation in the framework
of orthotropic nonlinear elasticity, under Dirichlet and mixed-boundary
conditions. We take a slab made of a soft matrix, reinforced with two families
of extensible fibers. We consider the case where the shear occurs along the
bissectrix of the angle between the two privileged directions aligned with the
fibers. We show that if the two families of parallel fibers are mechanically
equivalent, then only smooth solutions are possible, whereas if the mechanical
differences among the two families of fibers is pronounced, then strain
singularities may develop. We determine the precise conditions for the
existence of such singular solutions for the standard reinforcing orthotropic
model. We then extend our findings to some orthotropic models of interest in
biomechanical applications, and we discuss the possible relevance of the
singular solutions to biomechanics.


title: On Idempotent D-Norms

abstract:
  Replacing the spectral measure by a random vector $\bfZ$ allows the
representation of a max-stable distribution on $\R^d$ with standard negative
margins via a norm, called \emph{$D$-norm}, whose generator is $\bfZ$. The set
of $D$-norms can be equipped with a commutative multiplication type operation,
making it a semigroup with an identity element. This multiplication leads to
idempotent $D$-norms. We characterize the set of idempotent $D$-norms.
Iterating the multiplication provides a track of $D$-norms, whose limit exists
and is again a $D$-norm. If this iteration is repeatedly done on the same
$D$-norm, then the limit of the track is idempotent.


title:
Bandlimited Signal Reconstruction From the Distribution of Unknown
  Sampling Locations

abstract:
  We study the reconstruction of bandlimited fields from samples taken at
unknown but statistically distributed sampling locations. The setup is
motivated by distributed sampling where precise knowledge of sensor locations
can be difficult.
  Periodic one-dimensional bandlimited fields are considered for sampling.
Perfect samples of the field at independent and identically distributed
locations are obtained. The statistical realization of sampling locations is
not known. First, it is shown that a bandlimited field cannot be uniquely
determined with samples taken at statistically distributed but unknown
locations, even if the number of samples is infinite. Next, it is assumed that
the order of sample locations is known. In this case, using insights from
order-statistics, an estimate for the field with useful asymptotic properties
is designed. Distortion (mean-squared error) and central-limit are established
for this estimate.


title:
On some new model category structures from old, on the same underlying
  category

abstract:
  We make a study of ll-extensions of model category structures. We prove an
existence result of ll-extensions, present some specific and some rather formal
results about them and give an application of the existence result to the
homotopy theory of categories enriched over a monoidal model category.


title:
Recoil effects of a motional scatterer on single-photon scattering in
  one dimension

abstract:
  The scattering of a single photon with sufficiently high energy can cause a
recoil of a motional scatterer. We study its backaction on the photon's
coherent transport in one dimension by modeling the motional scatterer as a
two-level system, which is trapped in a harmonic potential. While the
reflection spectrum is of a single peak in the Lamb-Dicke limit, multi-peaks
due to phonon excitations can be observed in the reflection spectrum as the
trap becomes looser or the mass of the two-level system becomes smaller.


title: The cost of using exact confidence intervals for a binomial proportion

abstract:
  When computing a confidence interval for a binomial proportion p one must
choose between using an exact interval, which has a coverage probability of at
least 1-{\alpha} for all values of p, and a shorter approximate interval, which
may have lower coverage for some p but that on average has coverage equal to
1-\alpha. We investigate the cost of using the exact one and two-sided
Clopper--Pearson confidence intervals rather than shorter approximate
intervals, first in terms of increased expected length and then in terms of the
increase in sample size required to obtain a desired expected length. Using
asymptotic expansions, we also give a closed-form formula for determining the
sample size for the exact Clopper--Pearson methods. For two-sided intervals,
our investigation reveals an interesting connection between the frequentist
Clopper--Pearson interval and Bayesian intervals based on noninformative
priors.


title: Measurements of Neutrino Oscillation Angle theta_13

abstract:
  Neutrinos exhibit an interesting phenomenon called 'neutrino oscillation', in
which a neutrino changes its flavor after traveling some flight length. Many
experiments measured the mixing angles and mass differences, but the angle
$\theta_{13}$ had been unmeasured due to its smallness compared to others.
During 2011 and 2012, series of new-generation neutrino experiments reported
positive results in $\theta_{13}$ search, and its value has been determined to
be just below the previous upper limit. The non-zero result of $\theta_{13}$ is
a very good news for future of neutrino physics, since it opens a possibility
of measuring the CP violation phase in the lepton sector. An introduction to
neutrino oscillation and latest experimental results are presented. A detail is
put on Double Chooz reactor experiment, in which the author is involved.


title: Symmetry groups of Boolean Functions

abstract:
  We prove that every abelian permutation group, but known exceptions, is the
symmetry group of a boolean function. This solves the problem posed in the book
by Clote and Kranakis. In fact, our result is proved for a larger class of
groups, namely, for all groups contained in direct sums of regular groups.


title:
Sharp Raman Anomalies and Broken Adiabaticity at a Pressure Induced
  Transition from Band to Topological Insulator in Sb2Se3

abstract:
  The nontrivial electronic topology of a topological insulator is thus far
known to display signatures in a robust metallic state at the surface. Here, we
establish vibrational anomalies in Raman spectra of the bulk that signify
changes in electronic topology: an E2 g phonon softens unusually and its
linewidth exhibits an asymmetric peak at the pressure induced electronic
topological transition (ETT) in Sb2Se3 crystal. Our first-principles
calculations confirm the electronic transition from band to topological
insulating state with reversal of parity of electronic bands passing through a
metallic state at the ETT, but do not capture the phonon anomalies which
involve breakdown of adiabatic approximation due to strongly coupled dynamics
of phonons and electrons. Treating this within a four-band model of topological
insulators, we elucidate how nonadiabatic renormalization of phonons
constitutes readily measurable bulk signatures of an ETT, which will facilitate
efforts to develop topological insulators by modifying a band insulator.


title: Stabilizing switching signals for switched linear systems

abstract:
  This article deals with stability of continuous-time switched linear systems
under constrained switching. Given a family of linear systems, possibly
containing unstable dynamics, we characterize a new class of switching signals
under which the switched linear system generated by it and the family of
systems is globally asymptotically stable. Our characterization of such
stabilizing switching signals involves the asymptotic frequency of switching,
the asymptotic fraction of activation of the constituent systems, and the
asymptotic densities of admissible transitions among them. Our techniques
employ multiple Lyapunov-like functions, and extend preceding results both in
scope and applicability.


title: Operators generated by Morse-Smale mappings

abstract:
  Weighted shift operators $B$ in space $L^2(X,\mu)$ that are induced by
Morse-Smale type of mappings are considered. A description of the properties of
$B-\lambda I$ for $\lambda$ belonging to spectrum $\Sigma(B)$ is given. In
particular, there is the necessary and sufficient condition that $B-\lambda I$
be a one-sided invertible and the condition that set $Im(B-\lambda I)$ be
non-closed. These conditions use a new notation: an oriented decomposition of
oriented graph $G(X,\alpha)$ generated by mapping $\alpha$


title:
Nonlocal Young tests with Einstein-Podolsky-Rosen correlated particle
  pairs

abstract:
  We evaluate the nonlocal spatial interference displayed by
Einstein-Podolsky-Rosen entangled particle pairs after they pass through a
double grating arrangement. An entanglement criterion is derived which serves
to certify the underlying entanglement only from the observed spatial
correlations. We discuss the robustness of the scheme along with a number of
possible realizations with matter waves.


title: The PoGOLite control system and software

abstract:
  The autonomous control system of PoGOLite is presented. PoGOLite is a balloon
borne X-ray polarimeter designed to observe point sources. To obtain scientific
data with optimal efficiency, independent of the ground connection, the payload
control system has been made autonomous in most functions. The overall system
architecture and the interconnections between components, as well as the
automation philosophy and software, are described. Results of performance tests
are given.


title: The Pricing of A Moving Barrier Option

abstract:
  We provided an analytical representation of the price of a barrier option
with one type of special moving barrier. We consider the case that risk free
rate, dividend rate and stock volatility are time dependent. We get a pricing
formula and put call parity for barrier option when the moving barrier has a
special relation with risk free rate, dividend rate and stock volatility.


title:
Superintegrable systems with spin invariant with respect to the rotation
  group

abstract:
  Quantum nonrelativistic systems with $2\times2$ matrix potentials are
investigated. Physically, they simulate charged or neutral fermions with
non-trivial dipole momenta, interacting with an external electric field.
Assuming rotationally invariance of the Hamiltonian all such systems allowing
second order integrals of motion are identified. It is shown that the integrals
of motion can be effectively used to separate variables and to reduce the
systems to decoupled ordinary differential equations. Solutions for two of the
discussed problems are presented explicitly.


title: Analytical Pricing of Defaultable Bond with Stochastic Default Intensity

abstract:
  We provide analytical pricing formula of corporate defaultable bond with both
expected and unexpected default in the case with stochastic default intensity.
In the case with constant short rate and exogenous default recovery using PDE
method, we gave some pricing formula of the defaultable bond under the
conditions that 1)expected default recovery is the same with unexpected default
recovery; 2) default intensity follows one of 3 special cases of Willmott
model; 3) default intensity is uncorrelated with firm value. Then we derived a
pricing formula of a credit default swap. And in the case of stochastic short
rate and exogenous default recovery using PDE method, we gave some pricing
formula of the defaultable bond under the conditions that 1) expected default
recovery is the same with unexpected default recovery; 2) the short rate
follows Vasicek model; 3) default intensity follows one of 3 special cases of
Willmott model; 4) default intensity is uncorrelated with firm value; 5)
default intensity is uncorrelated with short rate. Then we derived a pricing
formula of a credit default swap. We give some credit spread analysis, too.


title: On removable singularities of meromorphic correspondences

abstract:
  We give a sufficient condition for a meromorphic correspondence to be a
holomorphic correspondence in a neighbourhood of a smooth real hypersurface


title:
Approximation by linear methods of classes of
  $(\psi,\bar\beta)-$differentiable functions

abstract:
  We calculate the least upper bounds for approximations in the metric of the
space $L_2$ by linear methods of summation of Fourier series on classes of
periodic functions $L^\psi_{\bar\beta,1}$ defined by sequences of multipliers
$\psi=\psi(k)$ and shifts of argument $\bar\beta=\beta_k$.


title:
Observational Upper Bound on the Cosmic Abundances of Negative-mass
  Compact Objects and Ellis Wormholes from the Sloan Digital Sky Survey Quasar
  Lens Search

abstract:
  The latest result in the Sloan Digital Sky Survey Quasar Lens Search (SQLS)
has set the first cosmological constraints on negative-mass compact objects and
Ellis wormholes. There are no multiple images lensed by the above two exotic
objects for $\sim 50000$ distant quasars in the SQLS data. Therefore, an upper
bound is put on the cosmic abundances of these lenses. The number density of
negative mass compact objects is $n<10^{-8} (10^{-4}) h^3 {\rm Mpc}^{-3}$ at
the mass scale $|M| > 10^{15} (10^{12}) M_\odot$, which corresponds to the
cosmological density parameter $|\Omega| < 10^{-4}$ at the galaxy-scale mass
range $|M|=10^{12-15}M_\odot$. The number density of the Ellis wormhole is
$n<10^{-4} h^3 {\rm Mpc}^{-3}$ for a range of the throat radius $a =
10^{1-4}$pc, which is much smaller than the Einstein ring radius.


title:
Genome-wide organization of eukaryotic pre-initiation complex is
  influenced by nonconsensus protein-DNA binding

abstract:
  Genome-wide binding preferences of the key components of eukaryotic
pre-initiation complex (PIC) have been recently measured with high resolution
in Saccharomyces cerevisiae by Rhee and Pugh (Nature (2012) 483:295-301). Yet
the rules determining the PIC binding specificity remain poorly understood. In
this study we show that nonconsensus protein-DNA binding significantly
influences PIC binding preferences. We estimate that such nonconsensus binding
contribute statistically at least 2-3 kcal/mol (on average) of additional
attractive free energy per protein, per core promoter region. The predicted
attractive effect is particularly strong at repeated poly(dA:dT) and
poly(dC:dG) tracts. Overall, the computed free energy landscape of nonconsensus
protein-DNA binding shows strong correlation with the measured genome-wide PIC
occupancy. Remarkably, statistical PIC binding preferences to both
TFIID-dominated and SAGA-dominated genes correlate with the nonconsensus free
energy landscape, yet these two groups of genes are distinguishable based on
the average free energy profiles. We suggest that the predicted nonconsensus
binding mechanism provides a genome-wide background for specific promoter
elements, such as transcription factor binding sites, TATA-like elements, and
specific binding of the PIC components to nucleosomes. We also show that
nonconsensus binding influences transcriptional frequency genome-wide.


title: Heavy flavor relaxation in a hadronic medium

abstract:
  Charm and bottom transport coefficients in a medium constituted of light
mesons, such as is formed in the hadronic phase of Heavy Ion Collisions, are
obtained within an effective field theory approach implementing heavy quark
symmetry and chiral symmetry breaking. Heavy flavor propagates in the medium as
$D/B$ and $D^*/B^*$ degrees of freedom, and unitarization of the lowest order
heavy-light meson amplitudes is used in order to reach high temperatures. The
latter accounts for dynamically generated resonances in isospin 1/2 channels, a
feature that leads to a more efficient heavy flavor diffussion. We discuss the
temperature and momentum dependence of the friction and diffusion coefficients
in a transport approach up to temperatures of about $T\simeq 150$ MeV, and
provide estimates of the charm/bottom relaxation lengths and momentum loss.
Implications for heavy meson spectrum observables in Heavy Ion Collisions are
discussed.


title: On quartics with lines of the second kind

abstract:
  We study the geometry of quartic surfaces in IP^3 that contain a line of the
second kind over algebraically closed fields of characteristic different from
2,3. In particular, we correct Segre's claims made for the complex case in
1943.


title:
Mass Corrections to Flavor-Changing Fermion-Graviton Vertices in the
  Standard Model

abstract:
  In a previous study, the flavor-changing fermion-graviton interactions have
been analyzed in the framework of the standard model, where analytical results
for the relevant form factors were obtained at the leading order in the
external fermion masses. These interactions arise at one-loop level by the
charged electroweak corrections to the fermion-graviton vertex, when the
off-diagonal flavor transitions in the corresponding charged weak currents are
taken into account. Due to the conservation of the energy-momentum tensor, the
corresponding form factors turn out to be finite and gauge invariant when
external fermions are on-shell. Here we extend this previous analysis by
including the exact dependence on the external fermion masses. Complete
analytical results are provided for all the relevant form factors to the
flavor-changing fermion-graviton transitions.


title: Homological dimensions and strongly idempotent ideals

abstract:
  Let A be an Artin algebra and e an idempotent in A. It is an interesting
topic to compare the homological dimension of the algebras A,A/AeA and eAe. For
example, in [2], the relation among the global dimension of these algebras is
discussed under the condition that AeA is a strongly idempotent ideal.
Motivated by this, we try to compare the finitistic dimension of these algebras
under certain homological conditions on AeA. In particular, under the condition
that AeA is a strongly idempotent ideal with finite projective dimension, we
prove that if the finitistic projective (or injective) dimension of eAe and
A/AeA are finite, then the finitistic projective (or injective) dimension of A
is finite. This is a generalized version of the main result in [1].


title: The gap phenomenon in parabolic geometries

abstract:
  The infinitesimal symmetry algebra of any Cartan geometry has maximum
dimension realized by the flat model, but often this dimension drops
significantly when considering non-flat geometries, so a gap phenomenon arises.
For general (regular, normal) parabolic geometries of type (G,P), we use Tanaka
theory to derive a universal upper bound on the submaximal symmetry dimension.
We use Kostant's version of the Bott-Borel-Weil theorem to show that this bound
is in fact sharp in almost all complex and split-real cases by exhibiting
(abstract) models. We explicitly compute all submaximal symmetry dimensions
when G is any complex or split-real simple Lie group.


title:
Hamiltonian dynamics in extended phase space for gravity and its
  consistency with Lagrangian formalism: a generalized spherically symmetric
  model as an example

abstract:
  Among theoretical issues in General Relativity the problem of constructing
its Hamiltonian formulation is still of interest. The most of attempts to
quantize Gravity are based upon Dirac generalization of Hamiltonian dynamics
for system with constraints. At the same time there exists another way to
formulate Hamiltonian dynamics for constrained systems guided by the idea of
extended phase space. We have already considered some features of this approach
in the previous MG12 Meeting by the example of a simple isotropic model. Now we
apply the approach to a generalized spherically symmetric model which imitates
the structure of General Relativity much better. In particular, making use of a
global BRST symmetry and the Noether theorem, we construct the BRST charge that
generates correct gauge transformations for all gravitational degrees of
freedom.


title:
{\alpha}-FeAs-free SmFeAsO1-xFx by low temperature sintering with slow
  cooling

abstract:
  We obtained amorphous-FeAs-free SmFeAsO1-xFx using a low temperature
sintering with slow cooling. SmFeAsO1-xFx is sintered at 980 {\deg}C for 40
hours and cooled slowly down to 600 {\deg}C. The low temperature sintering
suppresses the formation of amorphous FeAs, and the slow cooling introduces
much fluorine into SmFeAsO1-xFx. The superconductivity of this sample appears
at 57.8 K and the superconducting volume fraction reaches 96 %. To study the
change of fluorine concentration during the cooling process, samples are
quenched by water at 950 {\deg}C, 900 {\deg}C, 850 {\deg}C, 800 {\deg}C, 750
{\deg}C and 700 {\deg}C. It is found that fluorine is substituted not only at
the maximum heating temperature but also during the cooling process. The low
temperature sintering with slow cooling is very effective to obtain a
homogeneous SmFeAsO1-xFx with high fluorine concentration.


title:
First-principles determination of Heisenberg Hamiltonian parameters for
  the spin-1/2 kagome antiferromagnet ZnCu3(OH)6Cl2

abstract:
  Herbertsmithite (ZnCu3(OH)6Cl2) is often discussed as the best realization of
the highly frustrated antiferromagnetic kagome lattice known so far. We employ
density functional theory calculations to determine eight exchange coupling
constants of the underlying Heisenberg Hamiltonian. We find the nearest
neighbour coupling J1 to exceed all other couplings by far. However,
next-nearest neighbour kagome layer couplings of 0.019 J1 and interlayer
couplings of up to -0.035 J1 slightly modify the perfect antiferromagnetic
kagome Hamiltonian. Interestingly, the largest interlayer coupling is
ferromagnetic even without Cu impurities in the Zn layer. In addition, we
validate our DFT approach by applying it to kapellasite, a polymorph of
herbertsmithite which is known experimentally to exhibit competing exchange
interactions.


title: Dark energy from entanglement entropy

abstract:
  We show that quantum decoherence, in the context of observational cosmology,
can be connected to the cosmic dark energy. The decoherence signature could be
characterized by the existence of quantum entanglement between cosmological
eras. As a consequence, the Von Neumann entropy related to the entanglement
process, can be compared to the thermodynamical entropy in a homogeneous and
isotropic universe. The corresponding cosmological models are compatible with
the current observational bounds being able to reproduce viable equations of
state without introducing {\it a priori} any cosmological constant. In doing
so, we investigate two cases, corresponding to two suitable cosmic volumes,
$V\propto a^3$ and $V\propto H^{-3}$, and find two models which fairly well
approximate the current cosmic speed up. The existence of dark energy can be
therefore reinterpreted as a quantum signature of entanglement, showing that
the cosmological constant represents a limiting case of a more complicated
model derived from the quantum decoherence.


title:
A Fast Iterative Bayesian Inference Algorithm for Sparse Channel
  Estimation

abstract:
  In this paper, we present a Bayesian channel estimation algorithm for
multicarrier receivers based on pilot symbol observations. The inherent sparse
nature of wireless multipath channels is exploited by modeling the prior
distribution of multipath components' gains with a hierarchical representation
of the Bessel K probability density function; a highly efficient, fast
iterative Bayesian inference method is then applied to the proposed model. The
resulting estimator outperforms other state-of-the-art Bayesian and
non-Bayesian estimators, either by yielding lower mean squared estimation error
or by attaining the same accuracy with improved convergence rate, as shown in
our numerical evaluation.


title: Quantum metrology with a scanning probe atom interferometer

abstract:
  We use a small atomic Bose-Einstein condensate as an interferometric scanning
probe to map out a microwave field near a chip surface with a few micrometers
resolution. Using entanglement between the atoms we overcome the standard
quantum limit of interferometry by 4 dB and maintain enhanced performance for
interrogation times up to 20 ms. This demonstrates the usefulness of quantum
metrology with entangled states when the particle number is limited due to the
small probe size. Extending atom interferometry to micrometer spatial
resolution enables new applications in electromagnetic field sensing, surface
science, and the search for fundamental short-range interactions.


title: Kaon-nuclei interaction studies at low energies (the AMADEUS project)

abstract:
  The AMADEUS experiment aims to perform dedicated precision studies in the
sector of low-energy kaon-nuclei interaction at the DA\Phi NE collider at
LNF-INFN. In particular the experiment plans to perform measurements of the
debated deeply bound kaonic nuclear states (by stopping kaons in cryogenic
gaseous targets 3He and 4He) to explore the nature of the \Lambda(1405) in
nuclear environment and to measure the cross section of K- on light nuclei, for
K- momentum lower than 100 MeV/c. The AMADEUS dedicated setup will be installed
in the central region of the KLOE detector.


title:
Dynamics of the inner crust of neutron stars: hydrodynamics, elasticity
  and collective modes

abstract:
  We present calculations of the hydrodynamics of the inner crust of neutron
stars, where a superfluid neutron liquid coexists with a lattice of
neutron-rich nuclei. The long-wavelength collective oscillations are
combinations of phonons in the lattice and phonons in the superfluid neutrons.
Velocities of collective modes are calculated from information about effective
nucleon-nucleon interactions derived from Lattimer and Swesty's microscopic
calculations based on a compressible liquid drop picture of the atomic nuclei
and the surrounding neutrons.


title:
VHE Emission from PSR B1259-63/LS 2883 around 2010/2011 Periastron
  Passage observed with H.E.S.S

abstract:
  PSR B1259-63/LS 2883 is a binary system consisting of a 48 ms pulsar
orbitting around a Be star with an orbital period of ~3.4 years. The system was
detected at very high energies (VHE; E > 100 GeV) by the High Energy
Stereoscopic System (H.E.S.S.) during its periastron passages in 2004 and 2007.
Here we present new H.E.S.S. observations corresponding to its last periastron
passage, which occurred on December 15th 2010. These new observations partially
overlap with the beginning of a spectacular gamma-ray flare reported by the
Fermi-LAT. The H.E.S.S. observations show both flux and spectral properties
similar to those reported in previous periastron passages, without any
signature of the emission enhancement seen at GeV energies. A careful
statistical study based on the Fermi and H.E.S.S. lightcurves leads to the
conclusion that the GeV and TeV emission during the flare have a different
physical origin. This conlusion, in turn, allows to use Fermi-LAT measurements
of the GeV flux as upper limits for the modeling of the VHE emission.


title:
Continuous-time Quantum Monte Carlo Approach for Impurity Anderson
  Models with Phonon-assisted Hybridizations

abstract:
  We develop a continuous-time quantum Monte Carlo method based on a
strong-coupling expansion for Anderson impurity models with phonon-assisted
hybridizations for arbitrary number of phonon modes. As a benchmark, we
investigate the two-channel Anderson model with a single phonon, and
numerically demonstrate that an SO(5) susceptibility composed of
localized-electron charge and phonon-parity operators diverges logarithmically
at the non-Fermi liquid critical point in the model, which verifies the
predictions by the boundary conformal field theory[K. Hattori: Phys. Rev. B
{\bf 85} (2012) 214411].


title: Coherent Electron Transfer in Polyacetylene

abstract:
  We examine, using mixed classical-quantum electron-ion dynamics, electron
transfer in a donor-acceptor-like molecular junction system based on
polyacetylene. We identify two qualitatively-different transfer regimes:
hopping and tunnelling. We discuss the criteria for achieving each one and for
minimizing inelastic scattering and decoherence arising from the coupling to
the ions, and we connect our main results to quantities derived from electron
dynamics involving simpler, three-state model systems. We identify the
requirements to have near-ballistic transfer.


title:
The influence of $(n-n')$-mixing processes in $He^{*}(n) + He(1s^2)$
  collisions on $He^{*}(n)$ atoms' populations in weakly ionized helium plasmas

abstract:
  The results of semi-classical calculations of rate coefficients of
$(n-n')$-mixing processes due to collisions of Rydberg atoms $He^{*}(n)$ with
$He(1s^2)$ atoms are presented. It is assumed that these processes are caused
by the resonant energy exchange within the electron component of $He^{*}(n)+He$
collision system. The method is realized through the numerical simulation of
the $(n-n')$-mixing processes, and is applied for calculations of the
corresponding rate coefficients. The calculations are performed for the
principal quantum numbers $n,\mbox{} n'$ in ranges $4 \le n < n' \le 10$, and
the atom and electron temperatures, $T_a, T_e$, in domains $5000K \le T_{a} \le
T_{e} \le 20000K$. It is shown that the $(n-n')$-mixing processes can
significantly influence the populations of Rydberg atoms in non-equilibrium
weakly ionized helium plasmas with ionization degree $\sim 10^{-4}$. Therefore,
these processes have to be included in the appropriate models of such plasmas.


title: Equidistribution of Hecke points on the supersingular module

abstract:
  For a fixed prime p, we consider the (finite) set of supersingular elliptic
curves over $\bar{\mathbb{F}}$. Hecke operators act on this set. We compute the
asymptotic frequence with which a given supersingular elliptic curve visits
another under this action.


title: Hydrodynamics of air entrainment by moving contact lines

abstract:
  We study the dynamics of the interface between two immiscible fluids in
contact with a chemically homogeneous moving solid plate. We consider the
generic case of two fluids with any viscosity ratio and of a plate moving in
either directions (pulled or pushed in the bath). The problem is studied by a
combination of two models, namely an extension to finite viscosity ratio of the
lubrication theory and a Lattice Boltzmann method. Both methods allow to
resolve, in different ways, the viscous singularity at the triple contact
between the two fluids and the wall. We find a good agreement between the two
models particularly for small capillary numbers. When the solid plate moves
fast enough, the entrainment of one fluid into the other one can occur. The
extension of the lubrication model to the case of a non-zero air viscosity, as
developed here, allows us to study the dependence of the critical capillary
number for air entrainment on the other parameters in the problem (contact
angle and viscosity ratio).


title:
Assessing molecular line diagnostics of triggered star formation using
  synthetic observations

abstract:
  We investigate observational signatures of triggered star formation in bright
rimmed clouds (BRCs) by using molecular line transfer calculations based on
radiation-hydrodynamic radiatively-driven-implosion models. We find that for
BRCs the separation in velocity between the line profile peak of an optically
thick and an optically thin line is determined by both the observer viewing
angle and the density of the shell driving into the cloud. In agreement with
observations, we find that most BRC line profiles are symmetric and that
asymmetries can be either red or blue, in contrast to the blue-dominance
expected for a collapsing cloud. Asymmetries in the line profiles arise when an
optically thick line is dominated by the shell and an optically thin line is
dominated by the cloud interior to the shell. The asymmetries are red or blue
depending on whether the shell is moving towards or away from the observer
respectively. Using the known motions of the molecular gas in our models we
rule out the envelope expansion with core collapse mechanism as the cause of
the lack of blue-asymmetry in our simulated observations. We show that the
absence of a strong photon dominated region (PDR) around a BRC may not rule out
the presence of triggered star formation: if the BRC line profile has a strong
blue component then the shell is expected to be driving towards the observer,
suggesting that the cloud is being viewed from behind and the PDR is
obstructed. This could explain why BRCs such as SFO 80, 81 and 86 have a blue
secondary peak and only a weak PDR inferred at 8 microns. Finally we also test
the use of 12CO, 13CO and C18O as diagnostics of cloud mass, temperature and
column density. We find that the inferred conditions are in reasonable
agreement with those from the models.


title:
Tilting objects on tubular weighted projective lines: a cluster tilting
  approach

abstract:
  Using cluster tilting theory, we investigate tilting objects in the stable
category of vector bundles on a weighted projective line of weight type $(2, 2,
2, 2)$. More precisely, a tilting object consisting of rank-two bundles is
constructed via cluster tilting mutation. Moreover, the cluster tilting
approach also provides a new method to classify the endomorphism algebras of
tilting objects in the category of coherent sheaves and the associated bounded
derived category.


title:
Mass and rapidity dependent top quark forward-backward asymmetry in the
  effective Lagrangian approach

abstract:
  We study the invariant mass and rapidity dependent top quark forward-backward
asymmetry from the effective Lagrangian viewpoint. The Wilson coefficients are
constrained by the experimental observations and the concrete models that
reproduce the low energy effective Lagaragians are considered. Some of them are
disfavored and others relatively favored. For each cases, we estimate the
appropriacy of the effective Lagrangian approach.


title:
A simplified 461-nm laser system using blue laser diodes and a hollow
  cathode lamp for laser cooling of Sr

abstract:
  We develop a simplified light source at 461 nm for laser cooling of Sr
without frequency-doubling crystals but with blue laser diodes. An
anti-reflection coated blue laser diode in an external cavity (Littrow)
configuration provides an output power of 40 mW at 461 nm. Another blue laser
diode is used to amplify the laser power up to 110 mW by injection locking. For
frequency stabilization, we demonstrate modulation-free polarization
spectroscopy of Sr in a hollow cathode lamp. The simplification of the laser
system achieved in this work is of great importance for the construction of
transportable optical lattice clocks.


title: Enumeration of RNA complexes via random matrix theory

abstract:
  We review a derivation of the numbers of RNA complexes of an arbitrary
topology. These numbers are encoded in the free energy of the hermitian matrix
model with potential V(x)=x^2/2-stx/(1-tx), where s and t are respective
generating parameters for the number of RNA molecules and hydrogen bonds in a
given complex. The free energies of this matrix model are computed using the
so-called topological recursion, which is a powerful new formalism arising from
random matrix theory. These numbers of RNA complexes also have profound meaning
in mathematics: they provide the number of chord diagrams of fixed genus with
specified numbers of backbones and chords as well as the number of cells in
Riemann's moduli spaces for bordered surfaces of fixed topological type.

categories: q-bio.QM cond-mat.soft hep-th math-ph math.MP


title:
A Novel Exact Representation of Stationary Colored Gaussian Processes
  (Fractional Differential Approach)

abstract:
  A novel representation of functions, called generalized Taylor form, is
applied to the filtering of white noise processes. It is shown that every
Gaussian colored noise can be expressed as the output of a set of linear
fractional stochastic differential equation whose solution is a weighted sum of
fractional Brownian motions. The exact form of the weighting coefficients is
given and it is shown that it is related to the fractional moments of the
target spectral density of the colored noise.

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


title:
Magnetic field-induced gluonic (inverse) catalysis and pressure
  (an)isotropy in QCD

abstract:
  We study the influence of strong external magnetic fields on gluonic and
fermionic observables in the QCD vacuum at zero and nonzero temperatures, via
lattice simulations with N_f=1+1+1 staggered quarks of physical masses. The
gluonic action density is found to undergo magnetic catalysis at low
temperatures and inverse magnetic catalysis near and above the transition
temperature, similar to the quark condensate. Moreover, the gluonic action
develops an anisotropy: the chromo-magnetic field parallel to the external
field is enhanced, while the chromo-electric field in this direction is
suppressed. We demonstrate that the same hierarchy is obtained using the
Euler-Heisenberg effective action. Conversely, the topological charge density
correlator does not reveal a significant anisotropy up to magnetic fields eB~1
GeV^2. Furthermore, we show that the pressure remains isotropic even for
nonzero magnetic fields, if it is defined through a compression of the system
at fixed external field. In contrast, if the flux of the field is kept fixed
during the compression -- which is the situation realized in the lattice
simulation -- the pressure develops an anisotropy. We estimate the quark and
gluonic contributions to this anisotropy, and relate them to the magnetization
of the QCD vacuum. After performing electric charge renormalization, we obtain
an estimate for the magnetization, which indicates that QCD is paramagnetic.


title: Zeta functions for infinite graphs and functional equations

abstract:
  The definitions and main properties of the Ihara and Bartholdi zeta functions
for infinite graphs are reviewed. The general question of the validity of a
functional equation is discussed, and various possible solutions are proposed.


title:
Examination and experimental constraints of the stellar reaction rate
  factor $N_A < \sigma v >$ of the $^{18}$Ne($\alpha$,$p$)$^{21}$Na reaction at
  temperatures of X-Ray Bursts

abstract:
  The $^{18}$Ne($\alpha$,$p$)$^{21}$Na reaction is one key for the break-out
from the hot CNO-cycles to the $rp$-process. Recent papers have provided
reaction rate factors $N_A < \sigma v >$ which are discrepant by at least one
order of magnitude. The compatibility of the latest experimental results is
tested, and a partial explanation for the discrepant $N_A<\sigma v>$ is given.
A new rate factor is derived from the combined analysis of all available data.
The new rate factor is located slightly below the higher rate factor by Matic
{\it et al.}\ at low temperatures and significantly below at higher
temperatures whereas it is about a factor of five higher than the lower rate
factor recently published by Salter {\it et al.}


title: Surgery HQFT

abstract:
  Homotopy Quantum Field Theories (HQFTs) generalize more familiar Topological
Quantum Field Theories (TQFTs). In generalization of the surgery construction
of 3-dimensional TQFTs from modular categories, we use surgery to derive
3-dimensional HQFTs from G-modular categories.


title:
High-order harmonic generation with resonant core excitation by
  ultraintense x rays

abstract:
  High-order harmonic generation (HHG) is combined with resonant x-ray
excitation of a core electron into the transient valence vacancy that is
created in the course of the HHG process. To describe this setting, I develop a
two-active-electron quantum theory for a single atom assuming no Coulomb
interaction among the electrons; one electron performs a typical HHG three-step
process whereas another electron is excited (or even Rabi flops) by intense x
rays from the core shell into the valence hole after the first electron has
left the atom. Depending on the amplitude to find a vacancy in the valence and
the core, the returning continuum electron recombines with the valence and the
core, respectively, emitting high-order harmonic (HH) radiation that is
characteristic of the combined process. After presenting the theory of x-ray
boosted HHG for continuous-wave light fields, I develop a description for x-ray
pulses with a time-varying amplitude and phase. My prediction offers novel
prospects for nonlinear x-ray physics, attosecond x rays, and HHG-based
time-dependent chemical imaging involving core orbitals.


title:
Efficient MPS algorithm for periodic boundary conditions and
  applications

abstract:
  We present an implementation of an efficient algorithm for the calculation of
the spectrum of one-dimensional quantum systems with periodic boundary
conditions. This algorithm is based on a matrix product representation for
quantum states (MPS), and a similar representation for Hamiltonians and other
operators (MPO). It is significantly more efficient for systems of about 100
sites and more than for small quantum systems. We apply the formalism to
calculate the ground state and first excited state of a spin-1 Heisenberg ring
and deduce the size of the Haldane gap. The results are compared to previous
high-precision DMRG calculations. Furthermore, we study spin-1 systems with a
biquadratic nearest-neighbor interaction and show first results of an
application to a mesoscopic Hubbard ring of spinless Fermions which carries a
persistent current.


title: Pricing American options via multi-level approximation methods

abstract:
  In this article we propose a novel approach to reduce the computational
complexity of various approximation methods for pricing discrete time American
options. Given a sequence of continuation values estimates corresponding to
different levels of spatial approximation and time discretization, we propose a
multi-level low biased estimate for the price of an American option. It turns
out that the resulting complexity gain can be rather high and can even reach
the order (\varepsilon^{-1}) with (\varepsilon) denoting the desired precision.
The performance of the proposed multilevel algorithm is illustrated by a
numerical example of pricing Bermudan max-call options.


abstract:
  We study and classify Artin-Schelter regular algebras of dimension five with
two generators under an additional $\mathbb Z^2$-grading by Hilbert driven
Gr\"{o}bner basis computations. All the algebras we obtained are strongly
noetherian, Auslander regular, and Cohen-Macaulay. One of the results provides
an answer to Fl{\o}ystad-Vatne's question in the context of $\mathbb
Z^2$-grading. Our results also achieve a connection between Lyndon words and
Artin-Schelter regular algebras.


title: On uniqueness of tensor products of irreducible categorifications

abstract:
  In this paper, we propose an axiomatic definition for a tensor product
categorification. A tensor product categorification is an abelian category with
a categorical action of a Kac-Moody algebra g in the sense of Rouquier or
Khovanov-Lauda whose Grothendieck group is isomorphic to a tensor product of
simple modules. However, we require a much stronger structure than a mere
isomorphism of representations; most importantly, each such categorical
representation must have standardly stratified structure compatible with the
categorification functors, and with combinatorics matching those of the tensor
product. With these stronger conditions, we recover a uniqueness theorem
similar in flavor to that of Rouquier for categorifications of simple modules.
Furthermore, we already know of an example of such a categorification: the
representations of algebras T^\lambda previously defined by the second author
using generators and relations. Next, we show that tensor product
categorifications give a categorical realization of tensor product crystals
analogous to that for simple crystals given by cyclotomic quotients of KLR
algebras. Examples of such categories are also readily found in more classical
representation theory; for finite and affine type A, tensor product
categorifications can be realized as quotients of the representation categories
of cyclotomic q-Schur algebras.


title:
Equicontinuity of the family of the open discrete Orlicz--Sobolev
  mappings

abstract:
  The paper is devoted to the study of mappings with non--bounded
characteristics of quasiconformality. We investigate the interconnection
between the classes of the so-called ring $Q$-mappings and lower ring
$Q$-mappings. It is proved that open discrete lower ring $Q$-mappings are ring
$Q^{n-1}$-mappings at fixed point. As consequence we obtain the equicontinuity
of the class of the open discrete Orlicz--Sobolev mappings with finite
distortion at $n\ge 3.$


title: Five Texture Zeros and CP violation for the SM Quark Mass Matrices

abstract:
  The phenomenology of the five independent sets of $3\times 3$ quark mass
matrices with five texture zeros is carried through in full detail, including
predictions for the CP violation asymmetries. Our study is done without any
approximation, first analytical and then numerical.


title: The past and future evolution of a star like Betelgeuse

abstract:
  We discuss the physics and the evolution of a typical massive star passing
through an evolutionary stage similar to that of Betelgeuse. After a brief
introduction recalling various observed parameters of Betelgeuse, we discuss
the Pre-Main-Sequence phase (PMS), the Main-Sequence (MS) phase, the physics
governing the duration of the first crossing of the HR diagram, the red
supergiant stage (RSG), the post-red supergiant phases and the final fate of
solar metallicity stars with masses between 9 and 25 M$_\odot$. We examine the
impact of different initial rotation and of various prescriptions for the mass
loss rates during the red supergiant phase. We show that, whatever the initial
rotation rate (chosen between 0 and 0.7$\times\upsilon_{\rm crit}$,
$\upsilon_{\rm crit}$ being the surface equatorial velocity producing a
centrifugal acceleration balancing exactly the gravity) and the mass loss rates
during the RSG stage (varied between a standard value and 25 times that value),
a 15 M$_\odot$ star always ends its lifetime as a RSG and explodes as a type
II-P or II-L supernova.


title: Deformation of tropical Hirzebruch surfaces and enumerative geometry

abstract:
  We illustrate the use of tropical methods by generalizing a formula due to
Abramovich and Bertram, extended later by Vakil. Namely, we exhibit relations
between enumerative invariants of the Hirzebruch surfaces $\Sigma_n$ and
$\Sigma_{n+2}$, obtained by deforming the first surface to the latter.
  Our strategy involves a tropical counterpart of deformations of Hirzebruch
surfaces, and tropical enumerative geometry on a tropical surface in
three-space.


title: Velocity relaxation of a particle in a confined compressible fluid

abstract:
  The velocity relaxation of an impulsively forced spherical particle in a
fluid confined by two parallel plane walls is studied using a direct numerical
simulation approach. During the relaxation process, the momentum of the
particle is transmitted in the ambient fluid by viscous diffusion and sound
wave propagation, and the fluid flow accompanied by each mechanism has a
different character and affects the particle motion differently. Because of the
bounding walls, viscous diffusion is hampered, and the accompanying shear flow
is gradually diminished. However, the sound wave is repeatedly reflected and
spreads diffusely. As a result, the particle motion is governed by the sound
wave and backtracks differently in a bulk fluid. The time when the backtracking
of the particle occurs changes non-monotonically with respect to the
compressibility factor and is minimized at the characteristic compressibility
factor. This factor depends on the wall spacing, and the dependence is
different at small and large wall spacing regions based on the different
mechanisms causing the backtracking.


title: Solar Magnetic Carpet III: Coronal Modelling of Synthetic Magnetograms

abstract:
  This paper is the third in a series of papers working towards the
construction of a realistic, evolving, non-linear force-free coronal field
model for the solar magnetic carpet. Here, we present preliminary results of 3D
time-dependent simulations of the small-scale coronal field of the magnetic
carpet. Four simulations are considered, each with the same evolving
photospheric boundary condition: a 48 hr time series of synthetic magnetograms
produced from the model of Meyer, Mackay, van Ballegooijen and Parnell, 2011,
Solar Phys., 272, 29. Three simulations include a uniform, overlying coronal
magnetic field of differing strength, the fourth simulation includes no
overlying field. The build-up, storage and dissipation of magnetic energy
within the simulations is studied. In particular, we study their dependence
upon the evolution of the photospheric magnetic field and the strength of the
overlying coronal field. We also consider where energy is stored and dissipated
within the coronal field. The free magnetic energy built up is found to be more
than sufficient to power small-scale, transient phenomena such as nanoflares
and X-ray bright points, with the bulk of the free energy found to be stored
low down, between 0.5-0.8 Mm. The energy dissipated is presently found to be
too small to account for the heating of the entire quiet Sun corona. However,
the form and location of energy dissipation regions are in qualitative
agreement with what is observed on small scales on the Sun. Future MHD
modelling using the same synthetic magnetograms may lead to a higher energy
release.


title: Nuclear Masses and Neutron Stars

abstract:
  Precision mass spectrometry of neutron-rich nuclei is of great relevance for
astrophysics. Masses of exotic nuclides impose constraints on models for the
nuclear interaction and thus affect the description of the equation of state of
nuclear matter, which can be extended to describe neutron-star matter. With
knowledge of the masses of nuclides near shell closures, one can also derive
the neutron-star crustal composition. The Penning-trap mass spectrometer
ISOLTRAP at CERN-ISOLDE has recently achieved a breakthrough measuring the mass
of 82Zn, which allowed constraining neutron-star crust composition to deeper
layers (Wolf et al., PRL 110, 2013). We perform a more detailed study on the
sequence of nuclei in the outer crust of neutron stars with input from
different nuclear models to illustrate the sensitivity to masses and the
robustness of neutron-star models. The dominant role of the N=50 and N=82
closed neutron shells for the crustal composition is confirmed.


title: On Bipolar Soft Sets

abstract:
  We have studied the concept of bipolarity of information in the soft sets. We
have defined bipolar soft sets and basic operations of union, intersection and
complementation for bipolar soft sets. Examples of bipolar soft sets and an
application of bipolar soft sets in a decision making problem with general
algorithms have also been presented at the end.


title:
Model-Independent Identification of Inelastic WIMPs from Direct Dark
  Matter Detection Experiments

abstract:
  In this paper, we introduce model-independent data analysis procedures for
identifying inelastic WIMP-nucleus scattering as well as for reconstructing the
mass and the mass splitting of inelastic WIMPs simultaneously and separately.
Our simulations show that, with O(50) observed WIMP signals from one
experiment, one could already distinguish the inelastic WIMP scattering
scenarios from the elastic one. By combining two or more data sets with
positive signals, the WIMP mass and the mass splitting could even be
reconstructed with statistical uncertainties of less than a factor of two.


title:
The $R_\infty$ property for free groups, free nilpotent groups and free
  solvable groups

abstract:
  Let $F$ be either a free nilpotent group of a given class and of finite rank
or a free solvable group of a certain derived length and of finite rank. We
show precisely which ones have the $R_{\infty}$ property. Finally, we also show
that the free group of infinite rank does not have the $R_{\infty}$ property.


title:
Constant Unary Constraints and Symmetric Real-Weighted Counting
  Constraint Satisfaction Problems

abstract:
  A unary constraint (on the Boolean domain) is a function from {0,1} to the
set of real numbers. A free use of auxiliary unary constraints given besides
input instances has proven to be useful in establishing a complete
classification of the computational complexity of approximately solving
weighted counting Boolean constraint satisfaction problems (or #CSPs). In
particular, two special constant unary constraints are a key to an arity
reduction of arbitrary constraints, sufficient for the desired classification.
In an exact counting model, both constant unary constraints are always assumed
to be available since they can be eliminated efficiently using an arbitrary
nonempty set of constraints. In contrast, we demonstrate in an approximate
counting model, that at least one of them is efficiently approximated and thus
eliminated approximately by a nonempty constraint set. This fact directly leads
to an efficient construction of polynomial-time randomized
approximation-preserving Turing reductions (or AP-reductions) from #CSPs with
designated constraints to any given #CSPs composed of symmetric real-valued
constraints of arbitrary arities even in the presence of arbitrary extra unary
constraints.


title:
Gravitational four-fermion interaction and dynamics of the early
  Universe

abstract:
  If torsion exists, it generates gravitational four-fermion interaction
(GFFI), essential on the Planck scale. We analyze the influence of this
interaction on the Friedmann-Lemaitre-Robertson-Walker cosmology. Explicit
analytical solution is derived for the problem where both the energy-momentum
tensor generated by GFFI and the common ultrarelativistic energy-momentum
tensor are included. We demonstrate that gravitational four-fermion interaction
does not result in Big Bounce.


title:
Improved Primordial Non-Gaussianity Constraints from Measurements of
  Galaxy Clustering and the Integrated Sachs-Wolfe Effect

abstract:
  We present the strongest robust constraints on primordial non-Gaussianity
(PNG) from currently available galaxy surveys, combining large-scale clustering
measurements and their cross-correlations with the cosmic microwave background.
We update the data sets used by Giannantonio et al. (2012), and broaden that
analysis to include the full set of two-point correlation functions between all
surveys. In order to obtain the most reliable constraints on PNG, we advocate
the use of the cross-correlations between the catalogs as a robust estimator
and we perform an extended analysis of the possible systematics to reduce their
impact on the results. To minimize the impact of stellar contamination in our
luminous red galaxy (LRG) sample, we use the recent Baryon Oscillations
Spectroscopic Survey catalog of Ross et al. (2011). We also find evidence for a
new systematic in the NVSS radio galaxy survey similar to, but smaller than,
the known declination-dependent issue; this is difficult to remove without
affecting the inferred PNG signal, and thus we do not include the NVSS
auto-correlation function in our analyses. We find no evidence of primordial
non-Gaussianity; for the local-type configuration we obtain for the skewness
parameter $ -36 < f_{\mathrm{NL}} < 45 $ at 95 % c.l. ($5 \pm 21$ at $1\sigma$)
when using the most conservative part of our data set, improving previous
results; we also find no evidence for significant kurtosis, parameterized by
$g_{\mathrm{NL}}$. In addition to PNG, we simultaneously constrain dark energy
and find that it is required with a form consistent with a cosmological
constant.


title: Coefficient conditions for harmonic close-to-convex functions

abstract:
  New sufficient conditions, concerned with the coefficients of harmonic
functions $f(z)=h(z)+\bar{g(z)}$ in the open unit disk $\mathbb{U}$ normalized
by $f(0)=h(0)=h'(0)-1=0$, for $f(z)$ to be harmonic close-to-convex functions
are discussed. Furthermore, several illustrative examples and the image domains
of harmonic close-to-convex functions satisfying the obtained conditions are
enumerated.


title:
Astrometric and photometric initial mass functions from the UKIDSS
  Galactic Clusters Survey: IV Upper Sco

abstract:
  We present the results of a proper motion wide-field near-infrared survey of
the entire Upper Sco (USco) association (~160 square degrees) released as part
of the UKIRT Infrared Deep Sky (UKIDSS) Galactic Clusters Survey (GCS) Data
Release 10 (DR10). We have identified a sample of ~400 astrometric and
photometric member candidates combining proper motions and photometry in five
near-infrared passbands and another 286 with HK photometry and 2MASS/GCS proper
motions. We also provide revised membership for all previously published USco
low-mass stars and substellar members based on our selection and identify new
candidates, including in regions affected by extinction. We find negligible
variability between the two $K$-band epochs, below the 0.06 mag rms level. We
estimate an upper limit of 2.2% for wide common proper motions with projected
physical separations less than ~15000 au. We derive a disk frequency for USco
low-mass stars and brown dwarfs between 26 and 37%, in agreement with estimates
in IC348 and sigma Ori. We derive the mass function of the association and find
it consistent with the (system) mass function of the solar neighbourhood and
other clusters surveyed by the GCS in the 0.2-0.03 Msun mass range. We confirm
the possible excess of brown dwarfs in USco.


title: Spectral monodromy of non selfadjoint operators

abstract:
  We propose to build a combinatorial invariant, called the spectral monodromy,
from the spectrum of a single non-selfadjoint h-pseudodifferential operator
with two degrees of freedom in the semi-classical limit. Our inspiration comes
from the quantum monodromy defined for the joint spectrum of an integrable
system of n commuting selfadjoint h-pseudodifferential operators, given by S.
Vu Ngoc. The first simple case that we treat in this work is a normal operator.
In this case, the discrete spectrum can be identified with the joint spectrum
of an integrable quantum system. The second more complex case we propose is a
small perturbation of a selfadjoint operator with a classical integrability
property. We show that the discrete spectrum (in a small band around the real
axis) also has a combinatorial monodromy. The difficulty here is that we do not
know the description of the spectrum everywhere, but only in a Cantor type set.
In addition, we also show that the monodromy can be identified with the
classical monodromy defined by J. Duistermaat.


title:
Highly reproducible metal/graphene contacts and stable electrical
  performance by UV-Ozone treatment

abstract:
  Resist residue from the device fabrication process is a general and
significant source of the metal/graphene contact interface contamination. In
this paper, Ultraviolet-Ozone (UVO) treatment is proven to be an effective way
of cleaning the metal/graphene interface. Electrical measurements of devices,
which were fabricated by using UVO treatment of the metal/graphene contact
region, show that stable and highly reproducible low contact resistance between
metal and graphene is obtained without affecting the electrical properties of
the graphene channel itself.


title: Adaptive Spatial Aloha, Fairness and Stochastic Geometry

abstract:
  This work aims at combining adaptive protocol design, utility maximization
and stochastic geometry. We focus on a spatial adaptation of Aloha within the
framework of ad hoc networks. We consider quasi-static networks in which
mobiles learn the local topology and incorporate this information to adapt
their medium access probability (MAP) selection to their local environment. We
consider the cases where nodes cooperate in a distributed way to maximize the
global throughput or to achieve either proportional fair or max-min fair medium
access. In the proportional fair case, we show that nodes can compute their
optimal MAPs as solutions to certain fixed point equations. In the maximum
throughput case, the optimal MAPs are obtained through a Gibbs Sampling based
algorithm. In the max min case, these are obtained as the solution of a convex
optimization problem. The main performance analysis result of the paper is that
this type of distributed adaptation can be analyzed using stochastic geometry
in the proportional fair case. In this case, we show that, when the nodes form
a homogeneous Poisson point process in the Euclidean plane, the distribution of
the optimal MAP can be obtained from that of a certain shot noise process
w.r.t. the node Poisson point process and that the mean utility can also be
derived from this distribution. We discuss the difficulties to be faced for
analyzing the performance of the other cases (maximum throughput and max-min
fairness). Numerical results illustrate our findings and quantify the gains
brought by spatial adaptation in such networks.


title: Radio-frequency power generation

abstract:
  This paper reviews the main types of radio-frequency power amplifiers which
are, or may be, used for high-power hadron accelerators. It covers tetrodes,
inductive output tubes, klystrons and magnetrons with power outputs greater
than 10 kW continuous wave or 100 kW pulsed at frequencies from 50 MHz to 30
GHz. Factors affecting the satisfactory operation of amplifiers include
cooling, matching and protection circuits are discussed. The paper concludes
with a summary of the state of the art for the different technologies.


title: Trident pair production in a constant crossed field

abstract:
  We isolate the two-step mechanism involving a real intermediate photon from
the one-step mechanism involving a virtual photon for the trident process in a
constant crossed field. The two-step process is shown to agree with an
integration over polarised sub-processes. At low to moderate quantum
non-linearity parameter, the one-step process is found to be suppressed. When
the parameter is large, the two decay channels are comparable if the field
dimensions are not much greater than the formation length.


title:
Scanning Tunneling Spectroscopy of Ni/W(110): bcc and fcc properties in
  the second atomic layer

abstract:
  Nickel islands are grown on W(110) at elevated temperatures. Islands with a
thickness of two layers are investigated with scanning tunneling microscopy.
Spectroscopic measurements reveal that nanometer sized areas of the islands
exhibit distinctly different apparent heights and dI/dV spectra. Spin polarized
and paramagnetic band structure calculations indicate that the spectral
features are due to fcc(111) and bcc(110) orientations of the Ni film,
respectively.


title: Beam loading

abstract:
  We begin by giving a description of the radio-frequency generator-cavity-beam
coupled system in terms of basic quantities. Taking beam loading and cavity
detuning into account, expressions for the cavity impedance as seen by the
generator and as seen by the beam are derived. Subsequently methods of
beam-loading compensation by cavity detuning, radio-frequency feedback and
feedforward are described. Examples of digital radio-frequency phase and
amplitude control for the special case of superconducting cavities are also
given. Finally, a dedicated phase loop for damping synchrotron oscillations is
discussed.


title: Resolution of Single Spin-Flips of a Single Proton

abstract:
  The spin magnetic moment of a single proton in a cryogenic Penning trap was
coupled to the particle's axial motion with a superimposed magnetic bottle.
Jumps in the oscillation frequency indicate spin-flips and were identified
using a Bayesian analysis.


title: RF transport

abstract:
  This paper deals with the techniques of transport of high-power
radiofrequency (RF) power from a RF power source to the cavities of an
accelerator. Since the theory of electromagnetic waves in waveguides and of
waveguide components is very well explained in a number of excellent text books
it will limit itself on special waveguide distributions and on a number of,
although not complete list of, special problems which sometimes occur in RF
power transportation systems.


title:
An extended main sequence turn-off in the Small Magellanic Cloud star
  cluster NGC411

abstract:
  Based on new observations with the Wide Field Camera 3 onboard the Hubble
Space Telescope, we report the discovery of an extended main sequence turn-off
(eMSTO) in the intermediate-age star cluster NGC411. This is the second case of
an eMSTO being identified in a star cluster belonging to the Small Magellanic
Cloud (SMC), after NGC419. Despite the present masses of these two SMC clusters
differ by a factor of 4, the comparison between their colour--magnitude
diagrams (CMD) shows striking similarities, especially regarding the shape of
their eMSTOs. The loci of main CMD features are so similar that they can be
well described, in a first approximation, by the same mean metallicity,
distance and extinction. NGC411, however, presents merely a trace of secondary
red clump as opposed to its prominent manifestation in NGC419. This could be
due either to the small number statistics in NGC411, or by the star formation
in NGC419 having continued for 60 Myr longer than in NGC411. Under the
assumption that the eMSTOs are caused by different generations of stars at
increasing age, both clusters are nearly coeval in their first episodes of star
formation. The initial period of star formation, however, is slightly more
marked in NGC419 than in NGC411. We discuss these findings in the context of
possible scenarios for the origin of eMSTOs.


title: High-order harmonic generation from field-distorted orbitals

abstract:
  We investigate the effect on high-order harmonic generation of the distortion
of molecular orbitals by the driving laser field. Calculations for high-order
harmonic generation including orbital distortion are performed for N2. Our
results allow us to suggest that field-distortion is the reason why the
two-center interference minimum has never been observed experimentally in N2.
We propose experimental parameters which should allow an observation of the
two-center interference minimum.


title: Spin-orbit effects in nanowire-based wurtzite semiconductor quantum dots

abstract:
  We study the effect of the Dresselhaus spin-orbit interaction on the
electronic states and spin relaxation rates of cylindrical quantum dots defined
on quantum wires having wurtzite lattice structure. The linear and cubic
contributions of the bulk Dresselhaus spin-orbit coupling are taken into
account, along with the influence of a weak external magnetic field. The
previously found analytic solution for the electronic states of cylindrical
quantum dots with zincblende lattice structures with Rashba interaction is
extended to the case of quantum dots with wurtzite lattices. For the electronic
states in InAs dots, we determine the spin texture and the effective g-factor,
which shows a scaling collapse when plotted as a function of an effective
renormalized dot-size dependent spin-orbit coupling strength. The
acoustic-phonon-induced spin relaxation rate is calculated and the transverse
piezoelectric potential is shown to be the dominant one.


title: On the tensor degree of finite groups

abstract:
  We study the number of elements $x$ and $y$ of a finite group $G$ such that
$x \otimes y= 1_{_{G \otimes G}}$ in the nonabelian tensor square $G \otimes G$
of $G$. This number, divided by $|G|^2$, is called the tensor degree of $G$ and
has connection with the exterior degree, introduced few years ago in [P.
Niroomand and R. Rezaei, On the exterior degree of finite groups, Comm. Algebra
39 (2011), 335--343]. The analysis of upper and lower bounds of the tensor
degree allows us to find interesting structural restrictions for the whole
group.


title: Commissioning strategies and methods

abstract:
  Accelerator beam commissioning is a challenging and exciting period. It is
generally the first integrated operation of the many systems in an accelerator
and, most importantly, of the beam. First, general preparation is discussed.
Then general methods for initial beam commissioning are described, including
methods for transverse and longitudinal beam set-up. The particular emphasis
here is on tuning methods for linear accelerators.


title: Compositions and Fibonacci Identities

abstract:
  We study formulas expressing Fibonacci numbers as sums over compositions
using free submonoids of the free monoid of compositions with parts 1 and 2.


title:
Broad-band Spectroscopy of the Ongoing Large Eruption of the Luminous
  Blue Variable R71

abstract:
  The Luminous Blue Variable (LBV) R71 is currently undergoing an eruption,
which differs photometrically and spectroscopically from its last outburst in
the 1970s. Valuable information on the physics of LBV eruptions can be gained
by analyzing the spectral evolution during this eruption and by comparing R71's
present appearance to its previous outburst and its quiescent state. Here we
present the first spectra of an ongoing monitoring program with VLT/X-shooter
and compare them to archival VLT/UVES and MPG/ESO-2.2m/FEROS spectra from
2002-2011. The discussed data include pre-eruption spectra in 2002 and 2005, a
spectrum of the transitionary phase between quiescent and eruptive state in
2007, and spectra of the eruption in 2011-2012. The 2011-2012 spectra are
dominated by strong neutral and singly ionized metal absorption lines likely
formed in a large "pseudo-photosphere." We find an unusually low apparent
temperature of R71 of only ~6650 K; the star resembles a late F supergiant.
R71's visual lightcurve had a maximum in 2012 with mV ~ 8.7 mag. Given the
uncertainty in the extinction towards R71, this corresponds to a bolometric
luminosity of -9.8 mag to -10.3 mag. R71's 2011-2012 spectra do not show H I
and Fe II P Cyg profiles, which were present during its last outburst in the
1970s and which are normally observed during LBV outbursts. The rise in R71's
visual magnitude and the low apparent temperature of its pseudo-photosphere
during the current eruption are unprecedented for this star. R71 most likely
increased its bolometric luminosity by 0.4-1.3 mag compared to its quiescent
state. The very low temperature of its pseudo-photosphere implies a very
high-mass loss rate, a factor of 1000 higher than during the quiescence state.
No fast-moving material indicative of an explosion is observed (abridged).


title:
Total reaction cross section $\sigma_{\rm{reac}}$ of $\alpha$-induced
  reactions from elastic scattering: the example
  $^{140}$Ce($\alpha$,$\alpha$)$^{140}$Ce

abstract:
  Angular distributions of elastic $^{140}$Ce($\alpha$,$\alpha$)$^{140}$Ce
scattering are analyzed in the framework of the optical model from low energies
around the Coulomb barrier up to about 40\,MeV. From the local fits the total
reaction cross section $\sigma_{\rm{reac}}$ is extracted. This procedure
requires experimental scattering data with small uncertainties. The results for
$\sigma_{\rm{reac}}$ are compared to predictions of different systematic global
potentials. It is found that the total reaction cross section
$\sigma_{\rm{reac}}$ is well predicted from all global potentials under study
although the reproduction of the angular distributions is not perfect in all
cases. In addition, the lower energy limit for the extraction of
$\sigma_{\rm{reac}}$ from elastic scattering angular distributions is analyzed.
Finally, the potentials under study are used to calculate the
$^{143}$Nd(n,$\alpha$)$^{140}$Ce cross section, and the predictions are
compared to experimental data.


title: Coevolution and correlated multiplexity in multiplex networks

abstract:
  Distinct channels of interaction in a complex networked system define network
layers, which co-exist and co-operate for the system's function. Towards
realistic modeling and understanding such multiplex systems, we introduce and
study a class of growing multiplex network models in which different network
layers coevolve, and examine how the entangled growth of coevolving layers can
shape the overall network structure. We show analytically and numerically that
the coevolution can induce strong degree correlations across layers, as well as
modulate degree distributions. We further show that such a coevolution-induced
correlated multiplexity can alter the system's response to dynamical process,
exemplified by the suppressed susceptibility to a threshold cascade process.

categories: physics.soc-ph cond-mat.dis-nn cond-mat.stat-mech cs.SI


title:
New Methods for Timing Analysis of Transient Events, Applied to
  Fermi/GBM Magnetar Bursts

abstract:
  In order to discern the physical nature of many gamma-ray sources in the sky,
we must look not only in spectral and spatial dimensions, but also understand
their temporal variability. However, timing analysis of sources with a highly
transient nature, such as magnetar bursts, is difficult: standard Fourier
techniques developed for long-term variability generally observed, for example,
from AGN often do not apply. Here, we present newly developed timing methods
applicable to transient events of all kinds, and show their successful
application to magnetar bursts observed with Fermi/GBM. Magnetars are a prime
subject for timing studies, thanks to the detection of quasi-periodicities in
magnetar Giant Flares and their potential to help shed light on the structure
of neutron stars. Using state-of-the art statistical techniques, we search for
quasi-periodicities (QPOs) in a sample of bursts from Soft Gamma Repeater SGR
J0501+4516 observed with Fermi/GBM and provide upper limits for potential QPO
detections. Additionally, for the first time, we characterise the broadband
variability behaviour of magnetar bursts and highlight how this new information
could provide us with another way to probe these mysterious objects.


title:
Parametrization of coronal heating: spatial distribution and observable
  consequences

abstract:
  We investigate the difference in the spatial distribution of the energy input
for parametrizations of different mechanisms to heat the corona of the Sun and
possible impacts on the coronal emission. We use a 3D MHD model of a solar
active region as a reference and compare the Ohmic-type heating in this model
to parametrizations for alternating current (AC) and direct current (DC)
heating models, in particular, we use Alfven wave and MHD turbulence heating.
We extract the quantities needed for these two parametrizations from the
reference model and investigate the spatial distribution of the heat input in
all three cases, globally and along individual field lines. To study
differences in the resulting coronal emission we employ 1D loop models with a
prescribed heat input based on the heating rate we extracted along a bundle of
field lines. On average, all heating implementations show a roughly drop of the
heating rate with height. This also holds for individual field lines. While all
mechanism show a concentration of the energy input towards the low parts of the
atmosphere, for individual field lines the concentration towards the footpoints
is much stronger for the DC mechanisms than for the Alfven wave AC case. In
contrast, the AC model gives a stronger concentration of the emission towards
the footpoints. This is because the more homogeneous distribution of the energy
input leads to higher coronal temperatures and a more extended transition
region. The significant difference in the concentration of the heat input
towards the foot points for the AC and DC mechanisms, and the pointed
difference in the spatial distribution of the coronal emission for these cases
shows that the two mechanisms should be discriminable by observations. Before
drawing final conclusions, these parametrizations should be implemented in new
3D models in a more self-consistent way.


title:
Change in the Magnetic Domain Alignment Process at the Onset of a
  Frustrated Magnetic State in Ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 Double
  Perovskite

abstract:
  We have performed a combined study of magnetization hysteresis loops and time
dependence of the magnetization in a broad temperature range for the
ferrimagnetic La2Ni(Ni1/3Sb2/3)O6 double perovskite. This material has a
ferrimagnetic order transition at ~100 K and at lower temperatures (~ 20 K)
shows the signature of a frustrated state due to the presence of two competing
magnetic exchange interactions. The temperature dependence of the coercive
field shows an important upturn below the point where the frustrated state sets
in. The use of the magnetization vs. applied magnetic field hysteresis data,
together with the magnetization vs. time data provides a unique opportunity to
distinguish between different scenarios for the low temperature regime. From
our analysis, a strong domain wall pinning results the best scenario for the
low temperature regime. For temperatures larger than 20K the adequate scenario
seems to correspond to a weak domain wall pinning.


title: Modeling the interaction of DNA with alternating fields

abstract:
  We study the influence of a THz field on thermal properties of DNA molecules.
A Peyrard- Bishop-Dauxois model with the inclusion of a solvent interaction
term is considered. The THz field is included as a sinusoidal driven force in
the equation of mo tion. We show how under certain field and system parameters,
melting transition and bubble formation are modified.


title:
The consequences of gene flow for local adaptation and differentiation:
  A two-locus two-deme model

abstract:
  We consider a population subdivided into two demes connected by migration in
which selection acts in opposite direction. We explore the effects of
recombination and migration on the maintenance of multilocus polymorphism, on
local adaptation, and on differentiation by employing a deterministic model
with genic selection on two linked diallelic loci (i.e., no dominance or
epistasis). For the following cases, we characterize explicitly the possible
equilibrium configurations: weak, strong, highly asymmetric, and
super-symmetric migration, no or weak recombination, and independent or
strongly recombining loci. For independent loci (linkage equilibrium) and for
completely linked loci, we derive the possible bifurcation patterns as
functions of the total migration rate, assuming all other parameters are fixed
but arbitrary. For these and other cases, we determine analytically the maximum
migration rate below which a stable fully polymorphic equilibrium exists. In
this case, differentiation and local adaptation are maintained. Their degree is
quantified by a new multilocus version of $\Fst$ and by the migration load,
respectively. In addition, we investigate the invasion conditions of locally
beneficial mutants and show that linkage to a locus that is already in
migration-selection balance facilitates invasion. Hence, loci of much smaller
effect can invade than predicted by one-locus theory if linkage is sufficiently
tight. We study how this minimum amount of linkage admitting invasion depends
on the migration pattern. This suggests the emergence of clusters of locally
beneficial mutations, which may form `genomic islands of divergence'. Finally,
the influence of linkage and two-way migration on the effective migration rate
at a linked neutral locus is explored. Numerical work complements our
analytical results.


title:
Peaks in the CMBR power spectrum. II. Physical interpretation for any
  cosmological scenario

abstract:
  In a previous paper (part I), the mathematical properties of the cosmic
microwave background radiation power spectrum which presents oscillations were
discussed. Here, we discuss the physical interpretation: a power spectrum with
oscillations is a rather normal characteristic expected from any fluid with
clouds of overdensities that emits/absorb radiation or interact gravitationally
with the photons, and with a finite range of sizes and distances for those
clouds. The standard cosmological interpretation of "acoustic" peaks is just a
particular case; peaks in the power spectrum might be generated in scenarios
within some alternative cosmological model that have nothing to do with
oscillations due to gravitational compression in a fluid.
  We also calculate the angular correlation function of the anisotropies from
the WMAP-7yr and ACT data, in an attempt to derive the minimum number of
parameters a polynomial function should have to fit it: a set of polynomial
functions with a total of six free parameters, apart from the amplitude, is
enough to reproduce the first two peaks. However, the standard model with six
tunable free parameters also reproduces higher order peaks, giving the standard
model a higher confidence. At present, while no simple function with six free
parameters is found to give a fit as good as the one given by the standard
cosmological model, we may consider the predictive power of the standard model
beyond an instrumentalist approach (such as the Ptolemaic astronomy model of
the orbits of the planets).


title:
Control of beam propagation in optically written waveguides beyond the
  paraxial approximation

abstract:
  Beam propagation beyond the paraxial approximation is studied in an optically
written waveguide structure. The waveguide structure that leads to
diffractionless light propagation, is imprinted on a medium consisting of a
five-level atomic vapor driven by an incoherent pump and two coherent spatially
dependent control and plane-wave fields. We first study propagation in a single
optically written waveguide, and find that the paraxial approximation does not
provide an accurate description of the probe propagation. We then employ
coherent control fields such that two parallel and one tilted Gaussian beams
produce a branched waveguide structure. The tilted beam allows selective
steering of the probe beam into different branches of the waveguide structure.
The transmission of the probe beam for a particular branch can be improved by
changing the width of the titled Gaussian control beam as well as the intensity
of the spatially dependent incoherent pump field.


title:
Adaptive Aggregation Based Domain Decomposition Multigrid for the
  Lattice Wilson Dirac Operator

abstract:
  In lattice QCD computations a substantial amount of work is spent in solving
discretized versions of the Dirac equation. Conventional Krylov solvers show
critical slowing down for large system sizes and physically interesting
parameter regions. We present a domain decomposition adaptive algebraic
multigrid method used as a precondtioner to solve the "clover improved" Wilson
discretization of the Dirac equation. This approach combines and improves two
approaches, namely domain decomposition and adaptive algebraic multigrid, that
have been used seperately in lattice QCD before. We show in extensive numerical
test conducted with a parallel production code implementation that considerable
speed-up over conventional Krylov subspace methods, domain decomposition
methods and other hierarchical approaches for realistic system sizes can be
achieved.


title: Forking and JSJ decompositions in the free group

abstract:
  We give a description of the model theoretic relation of forking independence
in terms of the notion of JSJ decompositions in non abelian free groups.


title:
GPU accelerated maximum cardinality matching algorithms for bipartite
  graphs

abstract:
  We design, implement, and evaluate GPU-based algorithms for the maximum
cardinality matching problem in bipartite graphs. Such algorithms have a
variety of applications in computer science, scientific computing,
bioinformatics, and other areas. To the best of our knowledge, ours is the
first study which focuses on GPU implementation of the maximum cardinality
matching algorithms. We compare the proposed algorithms with serial and
multicore implementations from the literature on a large set of real-life
problems where in majority of the cases one of our GPU-accelerated algorithms
is demonstrated to be faster than both the sequential and multicore
implementations.


title: The Stability of BVRI Comparison Stars Near Selected TeV Blazars

abstract:
  We have measured Johnson BV and Cousins RI magnitudes for comparison stars
near five TeV blazars. We compare our values with published values, spanning 25
years in some cases, to identify those stars that are most likely proven
stable. To avoid zero-point offsets mimicking long-term variability, we based
our analysis on the standard deviation between measurements after a mean offset
between data sets was removed. We found most stars to be stable at the 0.04
magnitude level. We confirm two stars as variable and identify two others as
possibly being variable. In each of the five fields there are at least two
stars, and typically many more, that show no evidence of variability.


title:
Electronic and optical properties of FeSe2 polymorphs: solar cell
  absorber

abstract:
  Electronic and optical properties of semiconducting FeSe2 polymorphs
(marcasite and pyrite) were evaluated using density functional theory with
norm-conserving pseudopotential. Marcasite and pyrite of FeSe2 show indirect
band gaps of 0.86 eV and 0.67 eV respectively. Absorption coefficient is high
over a wide range of optical spectrum, indicating that these materials are
exploitable as solar cell absorber. Marcasite FeSe2 is found to be optically
anisotropic, whereas pyrite is isotropic. Mulliken Bond Population analysis
shows mixed ionic-covalent nature of bonding for both polymorphs. Effective
masses of electrons and holes were also calculated, which reinforce the
semiconducting nature of FeSe2


title:
Fast dimension-reduced climate model calibration and the effect of data
  aggregation

abstract:
  How will the climate system respond to anthropogenic forcings? One approach
to this question relies on climate model projections. Current climate
projections are considerably uncertain. Characterizing and, if possible,
reducing this uncertainty is an area of ongoing research. We consider the
problem of making projections of the North Atlantic meridional overturning
circulation (AMOC). Uncertainties about climate model parameters play a key
role in uncertainties in AMOC projections. When the observational data and the
climate model output are high-dimensional spatial data sets, the data are
typically aggregated due to computational constraints. The effects of
aggregation are unclear because statistically rigorous approaches for model
parameter inference have been infeasible for high-resolution data. Here we
develop a flexible and computationally efficient approach using principal
components and basis expansions to study the effect of spatial data aggregation
on parametric and projection uncertainties. Our Bayesian reduced-dimensional
calibration approach allows us to study the effect of complicated error
structures and data-model discrepancies on our ability to learn about climate
model parameters from high-dimensional data. Considering high-dimensional
spatial observations reduces the effect of deep uncertainty associated with
prior specifications for the data-model discrepancy. Also, using the
unaggregated data results in sharper projections based on our climate model.
Our computationally efficient approach may be widely applicable to a variety of
high-dimensional computer model calibration problems.


title: Relativistic Correction to J/psi and Upsilon Pair Production

abstract:
  The relativistic corrections to the productions of double J/psi, double
Upsilon, and J/psi+Upsilon at the Tevatron and the LHC were investigated within
the frame of nonrelativistic QCD. The ratios of short distance coefficients
between relativistic correction and leading order result for color singlet and
color octet states in large p_T limit are approximately -1,-11/3, respectively,
for pair production. And for J/psi+Upsilon process the ratio is -11/6 for the
CO channel. The K factors of relativistic corrections for color singlet and
color octet double J/psi production are -0.23 and -0.84 with adopting v^2=0.23.
The relativistic corrections significantly dilute the difference between the
shape of color-singlet differential cross sections and the color-octet's at
leading order. Also our results show that the single parton scattering model
may be enough to explain the LHCb data for the J/psi pair production.


title: Causality in concurrent systems

abstract:
  Concurrent systems identify systems, either software, hardware or even
biological systems, that are characterized by sets of independent actions that
can be executed in any order or simultaneously. Computer scientists resort to a
causal terminology to describe and analyse the relations between the actions in
these systems. However, a thorough discussion about the meaning of causality in
such a context has not been developed yet. This paper aims to fill the gap.
First, the paper analyses the notion of causation in concurrent systems and
attempts to build bridges with the existing philosophical literature,
highlighting similarities and divergences between them. Second, the paper
analyses the use of counterfactual reasoning in ex-post analysis in concurrent
systems (i.e. execution trace analysis).


title:
The influence of frequency-dependent radiative transfer on the
  structures of radiative shocks

abstract:
  Radiative shocks are shocks in a gas where the radiative energy and flux
coming from the very hot post-shock material are non-negligible in the shock's
total energy budget, and are often large enough to heat the material ahead of
the shock. Many simulations of radiative shocks, both in the contexts of
astrophysics and laboratory experiments, use a grey treatment of radiative
transfer coupled to the hydrodynamics. However, the opacities of the gas show
large variations as a function of frequency and this needs to be taken into
account if one wishes to reproduce the relevant physics. We have performed
radiation hydrodynamics simulations of radiative shocks in Ar using multigroup
(frequency dependent) radiative transfer with the HERACLES code. The opacities
were taken from the ODALISC database. We show the influence of the number of
frequency groups used on the dynamics and morphologies of subcritical and
supercritical radiative shocks in Ar gas, and in particular on the extent of
the radiative precursor. We find that simulations with even a low number of
groups show significant differences compared to single-group (grey)
simulations, and that in order to correctly model such shocks, a minimum number
of groups is required. Results appear to eventually converge as the number of
groups increases above 50. We were also able to resolve in our simulations of
supercritical shocks the adaptation zones which connect the cooling layer to
the final post-shock state and the precursor. Inside these adaptation zones, we
find that the radiative flux just ahead of the shock in one or several
high-opacity groups can heat the gas to a temperature higher than the
post-shock temperature. Through the use of Hugoniot curves, we have checked the
consistency of our radiation hydrodynamics scheme by showing that conservation
of mass, momentum and energy (including radiative flux) holds. ABRIDGED.


title:
Universality in the transport response of molecular wires physisorbed
  onto graphene electrodes

abstract:
  We analyze the low-voltage transport response of large molecular wires
bridging graphene electrodes, where the molecules are physisorbed onto the
graphene sheets by planar anchor groups. In our study, the sheets are pulled
away to vary the gap length and the relative atomic positions. The molecular
wires are also translated in directions parallel and perpendicular to the
sheets. We show that the energy position of the Breit-Wigner molecular
resonances is universal for a given molecule, in the sense that it is
independent of the details of the graphene edges, gaps lengths or of the
molecule positions. We discuss the need to converge carefully the k-sampling to
provide reasonable values of the conductance.


title:
Counterexamples in the theory of coerciveness for linear elliptic
  systems related to generalizations of Korn's second inequality

abstract:
  We show that the following generalized version of Korn's second inequality
with nonconstant measurable matrix valued coefficients P
  ||DuP+(DuP)^T||_q+||u||_q >= c ||Du||_q for u in W_0^{1,q}({\Omega};R^3),
1<q<{\infty} is in general false, even if P is in SO(3), while the
Legendre-Hadamard condition and ellipticity on C^n for the quadratic form |Du
P+(DuP)^T|^2 is satisfied. Thus Garding's inequality may be violated for
formally positive quadratic forms.


title:
Collision dynamics and entanglement generation of two initially
  independent and indistinguishable boson pairs in one-dimensional harmonic
  confinement

abstract:
  We investigate finite number effects in collisions between two states of an
initially well known number of identical bosons with contact interactions,
oscillating in the presence of harmonic confinement in one dimension. We
investigate two N/2 (interacting) ground states, which are initially displaced
from the trap center, and the effects of varying interaction strength. The
numerics focus on the simplest case of N=4. In the non-interacting case, such a
system would display periodic oscillation with a half harmonic oscillator
period (due to the left-right symmetry). With the addition contact interactions
between the bosons, collisions generate entanglement between each of the states
and distribute energy into other modes of the oscillator. We study the system
numerically via an exact diagonalization of the Hamiltonian with a finite
basis, investigating left/right number uncertainty as our primary measure of
entanglement. Additionally we study the time-evolution and equilibration of the
single-body von Neumann entropy for both the attractive and repulsive cases. We
identify parameter regimes for which attractive interactions create
qualitatively different behavior to repulsive interactions, due to the presence
of bound states (quantum solitons) and explain the processes behind this.


title: A toolkit for defect computations in Landau-Ginzburg models

abstract:
  We review the results of arXiv:1208.1481 on orientation reversal and duality
for defects in topological Landau-Ginzburg models, with the intention of
providing an easily accessible toolkit for computations. As an example we
include a proof of the main result on adjunctions in a special case, using
Pauli matrices. We also explain how to compute arbitrary correlators of
defect-decorated planar worldsheets, and briefly discuss the relation to
generalised orbifolds.