title:
Probing the physical and mathematical structure of $f(R)$ gravity by PSR
  $J0348+0432$

abstract:
  There are several approaches to extend General Relativity in order to explain
the phenomena related to the Dark Matter and Dark Energy. These theories,
generally called Extended Theories of Gravity, can be tested using observations
coming from relativistic binary systems as PSR $J0348+0432$. Using a class of
analytical $f(R)$-theories, one can construct the first time derivative of
orbital period of the binary systems starting from a quadrupolar gravitational
emission. Our aim is to set boundaries on the parameters of the theory in order
to understand if they are ruled out, or not, by the observations on PSR
$J0348+0432$. Finally, we have computed an upper limit on the graviton mass
showing that agree with constraint coming from other observations.


title: Weak-signal conversion from 1550nm to 532nm with 84% efficiency

abstract:
  We report on the experimental frequency conversion of a dim, coherent
continuous-wave light field from 1550nm to 532nm with an external photon-number
conversion efficiency of (84.4 +/- 1.5)%. We used sum-frequency generation,
which was realized in a standing-wave cavity built around a periodically poled
type I potassium titanyl phosphate (PPKTP) crystal, pumped by an intense field
at 810 nm. Our result is in full agreement with a numerical model. For
optimized cavity coupler reflectivities it predicts a conversion efficiency of
up to 93% using the same PPKTP crystal.


title: Effect of scalar leptoquarks on the rare decays of B_s meson

abstract:
  We study the effect of scalar leptoquarks on some rare decays of $B_s$ mesons
involving the quark level transition $b\rightarrow s$ $l^{+} l^{-}.$ In
particular we consider the decays $B_{s} \rightarrow \mu^{+} \mu^{-}$, $\bar
B_d^0 \to X_s \mu^+ \mu^-$ and $B_{s} \rightarrow \phi$ $\mu^{+} \mu^{-}$. The
leptoquark parameter space is constrained using the recently measured branching
ratio of the $B_{s} \rightarrow \mu^{+} \mu^{-}$ process at LHCb and CMS
experiments. Using such parameters we obtain the branching ratio, forward
backward asymmetry and the CP asymmetry parameters in the angular distribution
of $B_s \rightarrow \phi$ $\mu^+ \mu^-$ process.


title: Interstellar Dust models towards some IUE stars

abstract:
  We study the extinction properties of the composite dust grains, consisting
of host silicate spheroids and graphite as inclusions, using discrete dipole
approximation (DDA). We calculate the extinction cross sections of the
composite grains in the ultraviolet spectral region, 1200\AA -3200\AA and study
the variation in extinction as a function of the volume fraction of the
inclusions. We compare the model extinction curves with the observed
interstellar extinction curves obtained from the data given by the
International Ultraviolet Explorer (IUE) satellite. Our results for the
composite grains show a distinct variation in the extinction efficiencies with
the variation in the volume fraction of the inclusions. In particular, it is
found that the wavelength of peak absorption at `2175\AA' shifts towards the
longer wavelength with the variation in the volume fraction of inclusions. We
find that the composite grain models with the axial ratios viz. 1.33 and 2.0
fit the observed extinction reasonably well with a grain size distribution, a =
0.005-0.250$\mu m$. Moreover, our results of the composite grains clearly
indicate that the inhomogeneity in the grain structure, composition and the
surrounding media modifies the extinction properties of the grains.


title:
Effectiveness of Depolarizing noise in causing sudden death of
  entanglement

abstract:
  Continuing on the recent observation that sudden death of entanglement can
occur even when a single qubit of a two qubit state is exposed to noisy
environment, we examine the local effects of several noises on bipartite
qubit-qutrit and qutrit-qutrit systems. In order to rule out any initial
interactions with environment, we consider maximally entangled pure states of
qubit-qutrit and qutrit-qutrit systems for our analysis. We show that
depolarizing and generalized amplitude damping noise can cause sudden death of
entanglement in these states even when they act only on one part of the system.
We also show that sudden death of entanglement occurs much faster under the
action of depolarizing noise when compared to that due to generalized amplitude
damping. This result strengthens the observation that depolarizing noise is
more effective than other noise models in causing sudden death of entanglement.


title: Symmetry breaking and universality of decaying MHD Taylor-Green flows

abstract:
  We investigate the evolution and stability of a decaying magnetohydrodynamic
(MHD) Taylor-Green flow. The chosen flow has been shown to result in a steep
total energy spectrum with power law behaviour $k^{-2}$. We investigate the
symmetry breaking of this flow by exciting perturbations of different
amplitudes. It is shown that for any finite amplitude perturbation there is a
high enough Reynolds number for which the perturbation will grow enough at the
peak of dissipation rate resulting to a non-linear feedback in the flow and
subsequently break the Taylor-Green symmetries. In particular, we show that
symmetry breaking at large scales occurs if the amplitude of the perturbation
is $\rho_{crit} \sim Re^{-1}$ and at small scales occurs if $\rho_{crit} \sim
Re^{-3/2}$. This symmetry breaking modifies the scaling laws of the energy
spectra at the peak of dissipation rate away from the $k^{-2}$ scaling and
towards the classical $k^{-5/3}$ and $k^{-3/2}$ power laws.


title: Two-sided non-collapsing curvature flows

abstract:
  It was recently proved that embedded solutions of Euclidean hypersurface
flows with speeds given by concave (convex), degree one homogeneous functions
of the Weingarten map are interior (exterior) non-collapsing. These results
were subsequently extended to hypersurface flows in the sphere and hyperbolic
space.
  In the first part of the paper, we show that locally convex solutions are
exterior non-collapsing for a larger class of speed functions than previously
considered; more precisely, we show that the previous results hold when
convexity of the speed function is relaxed to inverse-concavity. We note that
inverse-concavity is satisfied by a large class of concave speed functions. As
a consequence, we obtain a large class of two-sided non-collapsing flows,
whereas previously two-sided non-collapsing was only known for the mean
curvature flow.
  In the second part of the paper, we demonstrate the utility of two sided
non-collapsing with a straightforward proof of convergence of compact, convex
hypersurfaces to round points.
  The proof of the non-collapsing estimate is similar to the previous results
mentioned, in that we show that the exterior ball curvature is a viscosity
supersolution of the linearised flow. The new ingredient is the following
observation: Since the function which provides an upper support in the
derivation of the viscosity inequality is defined on $M\times M$ (or $TM$ in
the `boundary case'), whereas the exterior ball curvature and the linearised
flow equation depend only on the first factor, we are privileged with a freedom
of choice in which second derivatives from the extra directions to include in
the calculation. The optimal choice is closely related to the class of
inverse-concave speed functions.


title: Some Intensive and Extensive Quantities in High-Energy Collisions

abstract:
  We review the evolution of some statistical and thermodynamical quantities
measured in difference sizes of high-energy collisions at different energies.
We differentiate between intensive and extensive quantities and discuss the
importance of their distinguishability in characterizing possible critical
phenomena of nuclear collisions at various energies with different initial
conditions.


title:
Cylindrical estimates for hypersurfaces moving by convex curvature
  functions

abstract:
  We prove a complete family of `cylindrical estimates' for solutions of a
class of fully non-linear curvature flows, generalising the cylindrical
estimate of Huisken-Sinestrari for the mean curvature flow. More precisely, we
show that, for the class of flows considered, an $(m+1)$-convex ($0\leq m\leq
n-2$) solution becomes either strictly $m$-convex, or its Weingarten map
approaches that of a cylinder $\R^m\times S^{n-m}$ at points where the
curvature is becoming large. This result complements the convexity estimate
proved by the authors and McCoy for the same class of flows.


title: A Survey on Device-to-Device Communication in Cellular Networks

abstract:
  Device-to-Device (D2D) communication was initially proposed in cellular
networks as a new paradigm to enhance network performance. The emergence of new
applications such as content distribution and location-aware advertisement
introduced new use-cases for D2D communications in cellular networks. The
initial studies showed that D2D communication has advantages such as increased
spectral efficiency and reduced communication delay. However, this
communication mode introduces complications in terms of interference control
overhead and protocols that are still open research problems. The feasibility
of D2D communications in LTE-A is being studied by academia, industry, and the
standardization bodies. To date, there are more than 100 papers available on
D2D communications in cellular networks and, there is no survey on this field.
In this article, we provide a taxonomy based on the D2D communicating spectrum
and review the available literature extensively under the proposed taxonomy.
Moreover, we provide new insights to the over-explored and under-explored areas
which lead us to identify open research problems of D2D communication in
cellular networks.


title: Advanced coding schemes against jamming in telecommand links

abstract:
  The aim of this paper is to study the performance of some coding schemes
recently proposed for updating the TC channel coding standard for space
applications, in the presence of jamming. Besides low-density parity-check
codes, that appear as the most eligible candidates, we also consider other
solutions based on parallel turbo codes and extended BCH codes. We show that
all these schemes offer very good performance, which approaches the theoretical
limits achievable.


title: An Alternative Explanation of Supernova Ia Data

abstract:
  Before 1998 the universe expansion was thought to be slowing down. After 1998
the universe expansion is thought to be accelerating up. This change of the
belief is motivated by the observed brightness of the high redshift supernova
Ia fainter than expected. In this paper it is argued that this change of the
belief is not necessary. There is a more reasonable explanation for the
observed brightness of the supernovae Ia fainter than expected. That is: the
universe space filled with the tenuous ionized gas; the Thomson Effect of free
electron in the ionized gas caused the observed brightness of the high redshift
supernova Ia fainter than expected. The observations of Warm-Hot Intergalactic
Medium (WHIM) support this explanation. The universe space filled with tenuous
ionized gas explanation will lead to the puzzle of the dark matter and dark
energy disappeared simultaneously


title:
Learning the Fundamental MIR Spectral Components of Galaxies with
  Non-Negative Matrix Factorisation

abstract:
  The mid-infrared (MIR) spectra observed with the \textit{Spitzer} Infrared
Spectrograph (IRS) provide a valuable dataset for untangling the physical
processes and conditions within galaxies.
  This paper presents the first attempt to blindly learn fundamental spectral
components of MIR galaxy spectra, using non-negative matrix factorisation
(NMF). NMF is a recently developed multivariate technique shown to be
successful in blind source separation problems. Unlike the more popular
multivariate analysis technique, principal component analysis, NMF imposes the
condition that weights and spectral components are non-negative. This more
closely resembles the physical process of emission in the mid-infrared,
resulting in physically intuitive components. By applying NMF to galaxy spectra
in the Cornell Atlas of Spitzer/IRS sources (CASSIS), we find similar
components amongst different NMF sets. These similar components include two for
AGN emission and one for star formation. [... ABBREVIATED...] We show an NMF
set with seven components can reconstruct the general spectral shape of a wide
variety of objects, though struggle to fit the varying strength of emission
lines. We also show that the seven components can be used to separate out
different types of objects. We model this separation with Gaussian Mixtures
modelling and use the result to provide a classification tool.
  We also show the NMF components can be used to separate out the emission from
AGN and star formation regions and define a new star formation/AGN diagnostic
which is consistent with all mid-infrared diagnostics already in use but has
the advantage that it can be applied to mid-infrared spectra with low signal to
noise or with limited spectral range. The 7 NMF components and code for
classification are made public on arxiv and are available at:
\url{https://github.com/pdh21/NMF_software/}


title: Finite generation of the cohomology of some skew group algebras

abstract:
  We prove that some skew group algebras have Noetherian cohomology rings, a
property inherited from their component parts. The proof is an adaptation of
Evens' proof of finite generation of group cohomology. We apply the result to a
series of examples of finite dimensional Hopf algebras in positive
characteristic.


title:
Demodulation of spatial carrier images : performance analysis of several
  algorithms using a single image

abstract:
  Optical full-field techniques have a great importance in modern experimental
mechanics. Even if they are reasonably spread among the university
laboratories, their diffusion in industrial companies remains very narrow for
several reasons, especially a lack of metrological performance assessment. A
full-field measurement can be characterized by its resolution, bias, measuring
range, and by a specific quantity, the spatial resolution. The present paper
proposes an original procedure to estimate in one single step the resolution,
bias and spatial resolution for a given operator (decoding algorithms such as
image correlation, low-pass filters, derivation tools ...). This procedure is
based on the construction of a particular multi-frequential field, and a Bode
diagram representation of the results. This analysis is applied to various
phase demodulating algorithms suited to estimate in-plane displacements


title: Bounds for left and right window cutoffs

abstract:
  The location and width of the time window in which a sequence of processes
converges to equilibrum are given under conditions of exponential convergence.
The location depends on the side: the left-window and right window cutoffs may
have different locations. Bounds on the distance to equilibrium are given for
both sides. Examples prove that the bounds are tight.


title:
A note on the second order universality at the edge of Coulomb gases on
  the plane

abstract:
  We consider in this note a class of two-dimensional determinantal Coulomb
gases confined by a radial external field. As the number of particles tends to
infinity, their empirical distribution tends to a probability measure supported
in a centered ring of the complex plane. A quadratic confinement corresponds to
the complex Ginibre Ensemble. In this case, it is also already known that the
asymptotic fluctuation of the radial edge follows a Gumbel law. We establish in
this note the universality of this edge behavior, beyond the quadratic case.
The approach, inspired by earlier works of Kostlan and Rider, boils down to
identities in law and to an instance of the Laplace method.


title:
Influence of ensemble boundary conditions (thermostat and barostat) on
  the deformation of amorphous polyethylene by molecular dynamics

abstract:
  Molecular dynamics simulations are increasingly being used to investigate the
structural evolution of polymers during mechanical deformation, but relatively
few studies focus on the influence of boundary conditions on this evolution, in
particular the dissipation of both heat and pressure through the periodic
boundaries during deformation. The research herein explores how the tensile
deformation of amorphous polyethylene, modelled with a united atom method
potential, is influenced by heat and pressure dissipation. The stress-strain
curves for the pressure dissipation cases (uniaxial tension) are in qualitative
agreement with experiments and show that heat dissipation has a large effect on
the strain hardening modulus calculated by molecular dynamics simulations. The
evolution of the energy associated with bonded and non-bonded terms was
quantified as a function of strain as well as the evolution of stress in both
the loading and non-loading directions to give insight into how the stress
state is altered within the elastic, yield, strain softening, and strain
hardening regions. The stress partitioning shows a competition between
`tensile' Van der Waal's interactions and `compressive' bond stretching forces,
with the characteristic yield stress peak clearly associated with the
non-bonded stress. The lack of heat dissipation had the largest effect on the
strain hardening regime, where an increase in the calculated temperature
correlated with faster chain alignment in the loading direction and more rapid
conformation changes. In part, these observations demonstrate the role that
heat and pressure dissipation play on deformation characteristics of amorphous
polymers, particularly for the strain hardening regime.


title: Some mathematical tools for the Lenski experiment

abstract:
  The Lenski experiment is a long term daily reproduction of Escherichia coli,
that has evidenced phenotypic and genetic evolutions along the years. Some
mathematical models, that could be usefull in understanding the results of that
experiment, are reviewed here: stochastic and deterministic growth, mutation
appearance and fixation, competition of species.


title: Simulation of Gene Regulatory Networks

abstract:
  This limited review is intended as an introduction to the fast growing
subject of mathematical modelling of cell metabolism and its biochemical
pathways, and more precisely on pathways linked to apoptosis of cancerous
cells. Some basic mathematical models of chemical kinetics, with emphasis on
stochastic models, are presented.


title:
From Public Outrage to the Burst of Public Violence: An Epidemic-Like
  Model

abstract:
  This study extends classical models of spreading epidemics to describe the
phenomenon of contagious public outrage, which eventually leads to the spread
of violence following a disclosure of some unpopular political decisions and/or
activity. Accordingly, a mathematical model is proposed to simulate from the
start, the internal dynamics by which an external event is turned into internal
violence within a population. Five kinds of agents are considered: "Upset" (U),
"Violent" (V), "Sensitive" (S), "Immune" (I), and "Relaxed" (R), leading to a
set of ordinary differential equations, which in turn yield the dynamics of
spreading of each type of agents among the population. The process is stopped
with the deactivation of the associated issue. Conditions coinciding with a
twofold spreading of public violence are singled out. The results shed a new
light to understand terror activity and provides some hint on how to curb the
spreading of violence within population globally sensitive to specific world
issues. Recent world violent events are discussed.


title:
Multiobjective optimization using Gaussian process emulators via
  stepwise uncertainty reduction

abstract:
  Optimization of expensive computer models with the help of Gaussian process
emulators in now commonplace. However, when several (competing) objectives are
considered, choosing an appropriate sampling strategy remains an open question.
We present here a new algorithm based on stepwise uncertainty reduction
principles to address this issue. Optimization is seen as a sequential
reduction of the volume of the excursion sets below the current best solutions,
and our sampling strategy chooses the points that give the highest expected
reduction. Closed-form formulae are provided to compute the sampling criterion,
avoiding the use of cumbersome simulations. We test our method on numerical
examples, showing that it provides an efficient trade-off between exploration
and intensification.


title:
Local inverse scattering at fixed energy in spherically symmetric
  asymptotically hyperbolic manifolds

abstract:
  In this paper, we adapt the well-known \emph{local} uniqueness results of
Borg-Marchenko type in the inverse problems for one dimensional Schr{\"o}dinger
equation to prove \emph{local} uniqueness results in the setting of inverse
\emph{metric} problems. More specifically, we consider a class of spherically
symmetric manifolds having two asymptotically hyperbolic ends and study the
scattering properties of massless Dirac waves evolving on such manifolds. Using
the spherical symmetry of the model, the stationary scattering is encoded by a
countable family of one-dimensional Dirac equations. This allows us to define
the corresponding transmission coefficients $T(\lambda,n)$ and reflection
coefficients $L(\lambda,n)$ and $R(\lambda,n)$ of a Dirac wave having a fixed
energy $\lambda$ and angular momentum $n$. For instance, the reflection
coefficients $L(\lambda,n)$ correspond to the scattering experiment in which a
wave is sent from the \emph{left} end in the remote past and measured in the
same left end in the future. The main result of this paper is an inverse
uniqueness result local in nature. Namely, we prove that for a fixed $\lambda
\not=0$, the knowledge of the reflection coefficients $L(\lambda,n)$ (resp.
$R(\lambda,n)$) - up to a precise error term of the form $O(e^{-2nB})$ with
$B\textgreater{}0$ - determines the manifold in a neighbourhood of the left
(resp. right) end, the size of this neighbourhood depending on the magnitude
$B$ of the error term. The crucial ingredients in the proof of this result are
the Complex Angular Momentum method as well as some useful uniqueness results
for Laplace transforms.


title: The Micromegas Project for the ATLAS Upgrade

abstract:
  Micromegas is one of the detector technologies (along with the small Thin Gap
Chambers) that has been chosen for precision tracking and triggering purposes
of the ATLAS muon forward detectors in the view of LHC luminosity increase. To
fulfill the requirements of such upgrade, several prototype micromegas
detectors were tested in recent test beam campaigns with high energy hadron
beams at CERN. Performance studies and results on spatial resolution for
perpendicular and inclined tracks, efficiency, as well detector performance and
comparison to simulation in a magnetic field are presented. Moreover, an
overview of detector performance after neutron, X-ray, gammas and alphas
exposure and construction achievements of large area micromegas detectors are
presented.


title: Interaction Quench in Nonequilibrium Luttinger Liquids

abstract:
  We study the relaxation dynamics of a nonequilibrium Luttinger liquid after a
sudden interaction switch-on ("quench"), focussing on a double-step initial
momentum distribution function. In the framework of the non-equilibrium
bosonization, the results are obtained in terms of singular Fredholm
determinants that are evaluated numerically and whose asymptotics are found
analytically. While the quasi-particle weights decay exponentially with time
after the quench, this is not a relaxation into a thermal state, in view of the
integrability of the model. The steady-state distribution emerging at infinite
times retains two edges which support Luttinger-liquid-like power-law
singularities smeared by dephasing. The obtained critical exponents and the
dephasing length are found to depend on the initial nonequilibrium state.


title: Toward a Theory of Creative Inklings

abstract:
  It is perhaps not so baffling that we have the ability to develop, refine,
and manifest a creative idea, once it has been conceived. But what sort of a
system could spawn the initial seed of creativity from which an idea grows?
This paper looks at how the mind is structured in such a way that we can
experience a glimmer of insight or inkling of artistic inspiration.


title:
A Conceptual Network-Based Approach to Inferring the Cultural
  Evolutionary History of the Baltic Psaltery

abstract:
  The application of conventional phylogenetic techniques for inferring
cultural history is problematic due to differences in the nature of information
transmission in biological and cultural realms. In culture, units of
transmission are not just measurable attributes, but communicable concepts.
Therefore, relatedness amongst cultural elements often resides at the
conceptual level not captured by traditional phylogenetic methods. This paper
takes a cognitively inspired approach to analyzing material cultural history.
We show that combining data for physical attributes of cultural artifacts with
conceptual information can uncover cultural influences among different
ethnolinguistic groups, and reveal new patterns of cultural ancestry. Using the
Baltic psaltery, a musical instrument with a well-documented ethnographic and
archaeological record, we recovered a previously unacknowledged pattern of
historical relationship that is more congruent with geographical distribution
and temporal data than is obtained with other approaches.


title: Green-hyperbolic operators on globally hyperbolic spacetimes

abstract:
  Green-hyperbolic operators are linear differential operators acting on
sections of a vector bundle over a Lorentzian manifold which possess advanced
and retarded Green's operators. The most prominent examples are wave operators
and Dirac-type operators. This paper is devoted to a systematic study of this
class of differential operators. For instance, we show that this class is
closed under taking restrictions to suitable subregions of the manifold, under
composition, under taking "square roots", and under the direct sum
construction. Symmetric hyperbolic systems are studied in detail.


title:
Transverse charge and magnetization densities in the nucleon's chiral
  periphery

abstract:
  In the light-front description of nucleon structure the electromagnetic form
factors are expressed in terms of frame-independent transverse densities of
charge and magnetization. Recent work has studied the transverse densities at
peripheral distances b = O(M_pi^{-1}), where they are governed by universal
chiral dynamics and can be computed in a model-independent manner. Of
particular interest is the comparison of the peripheral charge and
magnetization densities. We summarize (a) their interpretation as
spin-independent and -dependent current matrix elements; (b) the leading-order
chiral effective field theory results; (c) their mechanical interpretation in
the light-front formulation; (d) the large-N_c limit of QCD and the role of
Delta intermediate states; (e) the connection with generalized parton
distributions and peripheral high-energy scattering processes.


title: Pseudo-Marginal Bayesian Inference for Gaussian Processes

abstract:
  The main challenges that arise when adopting Gaussian Process priors in
probabilistic modeling are how to carry out exact Bayesian inference and how to
account for uncertainty on model parameters when making model-based predictions
on out-of-sample data. Using probit regression as an illustrative working
example, this paper presents a general and effective methodology based on the
pseudo-marginal approach to Markov chain Monte Carlo that efficiently addresses
both of these issues. The results presented in this paper show improvements
over existing sampling methods to simulate from the posterior distribution over
the parameters defining the covariance function of the Gaussian Process prior.
This is particularly important as it offers a powerful tool to carry out full
Bayesian inference of Gaussian Process based hierarchic statistical models in
general. The results also demonstrate that Monte Carlo based integration of all
model parameters is actually feasible in this class of models providing a
superior quantification of uncertainty in predictions. Extensive comparisons
with respect to state-of-the-art probabilistic classifiers confirm this
assertion.


title: Vulnerability of state-interdependent networks under malware spreading

abstract:
  Computer viruses are evolving by developing spreading mechanisms based on the
use of multiple vectors of propagation. The use of the social network as an
extra vector of attack to penetrate the security measures in IP networks is
improving the effectiveness of malware, and have therefore been used by the
most aggressive viruses, like Conficker and Stuxnet. In this work we use
interdependent networks to model the propagation of these kind of viruses. In
particular, we study the propagation of a SIS model on interdependent networks
where the state of each node is layer-independent and the dynamics in each
network follows either a contact process or a reactive process, with different
propagation rates. We apply this study to the case of existing multilayer
networks, namely a Spanish scientific community of Statistical Physics, formed
by a social network of scientific collaborations and a physical network of
connected computers in each institution. We show that the interplay between
layers increases dramatically the infectivity of viruses in the long term and
their robustness against immunization.


title: A short note on strongly flat covers of acts over monoids

abstract:
  Recently two different concepts of covers of acts over monoids have been
studied. That based on coessential epimorphisms and that based on Enochs'
definition of a flat cover of a module over a ring. Two recent papers have
suggested that in the former case, strongly flat covers are not unique. We show
that these examples are in fact false and so the question of uniqueness appears
to still remain open. In the latter case, we re-present an example due to Kruml
that demonstrates that, unlike the case for flat covers of modules, strongly
flat covers of S-acts do not always exist.


title: Enhancement of the radar signal of air showers due to time compression

abstract:
  We investigate the feasibility of detecting extensive air showers by the
radar technique at viewing angles smaller than $\sim 25^\circ$ to the shower
axis. Considering a bistatic radar setup and shower geometries in which the
receiver points into the arriving shower, we simulate reflection of radio waves
off the short-lived plasma produced by the high-energy shower particles in the
air. Using the Thomson cross-section for scattering of radio waves and summing
coherently contributions of the reflected radio wave over the volume of the
plasma disk, we obtain the time evolution of the signal. We analyze the
spectral power density of the radar echo and the received power. Based on the
obtained results, we discuss possible modes of the radar detection of extensive
air showers.


title: Advanced channel coding for space mission telecommand links

abstract:
  We investigate and compare different options for updating the error
correcting code currently used in space mission telecommand links. Taking as a
reference the solutions recently emerged as the most promising ones, based on
Low-Density Parity-Check codes, we explore the behavior of alternative schemes,
based on parallel concatenated turbo codes and soft-decision decoded BCH codes.
Our analysis shows that these further options can offer similar or even better
performance.


title:
The ultraluminous X-ray sources NGC 1313 X-1 and X-2: a broadband study
  with NuSTAR and XMM-Newton

abstract:
  We present the results of NuSTAR and XMM-Newton observations of the two
ultraluminous X-ray sources (ULX) NGC 1313 X-1 and X-2. The combined spectral
bandpass of the two satellites enables us to produce the first spectrum of X-1
between 0.3 and 30 keV, while X-2 is not significantly detected by NuSTAR above
10 keV. The NuSTAR data demonstrate that X-1 has a clear cutoff above 10 keV,
whose presence was only marginally detectable with previous X-ray observations.
This cutoff rules out the interpretation of X-1 as a black hole in a standard
low/hard state, and it is deeper than predicted for the downturn of a broadened
iron line in a reflection-dominated regime. The cutoff differs from the
prediction of a single-temperature Comptonization model. Further, a cold
disk-like black body component at ~0.3 keV is required by the data, confirming
previous measurements by XMM-Newton only. We observe a spectral transition in
X-2, from a state with high luminosity and strong variability to a
lower-luminosity state with no detectable variability, and we link this
behavior to a transition from a super-Eddington to a sub-Eddington regime.


title: Modulus of convexity for operator convex functions

abstract:
  Given an operator convex function $f(x)$, we obtain an operator-valued lower
bound for $cf(x) + (1-c)f(y) - f(cx + (1-c)y)$, $c \in [0,1]$. The lower bound
is expressed in terms of the matrix Bregman divergence. A similar inequality is
shown to be false for functions that are convex but not operator convex.


title: Avoiding a Spanning Cluster in Percolation Models

abstract:
  When dynamics in a system proceeds under suppressive external bias, the
system can undergo an abrupt phase transition, as it occurs for example in the
epidemic spreading. Recently, an explosive percolation (EP) model was
introduced in line with such phenomena. The order of the EP transition has not
been clarified in a unified framework covering low dimensional systems and the
mean-field limit. We introduce a stochastic model, in which a rule for dynamics
is designed to avoid the formation of a spanning cluster through competitive
selection in Euclidean space. We show by heuristic arguments that, in the
thermodynamic limit and depending on a control parameter, the EP transition can
be either continuous or discontinuous if $d < d_c$ and is always continuous if
$d \geq d_c$, where $d$ is the spatial dimension and $d_c$ the upper critical
dimension.


title: Characterizing small planets transiting small stars with SPIRou

abstract:
  SPIRou, a near infrared spectropolarimeter, is a project of new instrument to
be mounted at the Canada France Hawaii Telescope in 2017. One of the main
objectives of SPIRou is to reach a radial velocity accuracy better than 1 m/s
in the YJHK bands. SPIRou will make a cornerstone into the characterization of
Earth-like planets, where the exoplanet statistics is very low. This is even
more true for planets transiting M dwarfs, since only 3 low-mass planets have
been secured so far to transit such stars. We present here all the synergies
that SPIRou will provide to and benefit from photometric transit-search
programs from the ground or from space (Kepler, CHEOPS, TESS, PLATO 2.0). We
also discuss the impact of SPIRou for the characterization of planets orbiting
actives stars.


title: Microscopic Calculation of Fusion: Light to Heavy Systems

abstract:
  The density-constrained time-dependent Hartree-Fock (DC-TDHF) theory is a
fully microscopic approach for calculating heavy-ion interaction potentials and
fusion cross sections below and above the fusion barrier. We discuss recent
applications of DC-TDHF method to fusion of light and heavy neutron-rich
systems.


title:
Diamond as a solid state quantum computer with a linear chain of nuclear
  spins system

abstract:
  By removing a $^{12}C$ atom from the tetrahedral configuration of the
diamond, replace it by a $^{13}C$ atom, and repeating this in a linear
direction, it is possible to have a linear chain of nuclear spins one half and
to build a solid state quantum computer. One qubit rotation and controlled-not
(CNOT) quantum gates are obtained immediately from this configuration, and CNOT
quantum gate is used to determined the design parameters of this quantum
computer.


title:
Off-shell effects in the relativistic mean field model and their role in
  CC (anti)neutrino scattering at MiniBooNE kinematics

abstract:
  The relativistic mean field (RMF) model is used to describe nucleons in the
nucleus and thereby to evaluate the effects of having dynamically off-shell
spinors. Compared with free, on-shell nucleons as employed in some other
models, within the RMF nucleons are described by relativistic spinors with
strongly enhanced lower components. In this work it is seen that for MiniBooNE
kinematics, neutrino charged-current quasielastic cross sections show some
sensitivity to these off-shell effects, while for the antineutrino-nucleus case
the total cross sections are seen to be essentially independent of the
enhancement of the lower components. As was found to be the case when comparing
the RMF results with the neutrino-nucleus data, the present impulse
approximation predictions within the RMF also fall short of the MiniBooNE
antineutrino-nucleus data.


title: Transverse Single Spin Asymmetries and Charmonium Production

abstract:
  We estimate transverse spin single spin asymmetry(TSSA) in the process
$e+p^\uparrow \to J/\psi +X$ using color evaporation model of charmonium
production. We take into account transverse momentum dependent(TMD) evolution
of Sivers function and parton distribution function and show that the there is
a reduction in the asymmetry as compared to our earlier estimates wherein the
$Q^2$ - evolution was implemented only through DGLAP evolution of unpolarized
gluon densities.


title: Energy decay in three-dimensional freely cooling granular gas

abstract:
  The kinetic energy of a freely cooling granular gas decreases as a power law
$t^{-\theta}$ at large times $t$. Two theoretical conjectures exist for the
exponent $\theta$. One based on ballistic aggregation of compact spherical
aggregates predicts $\theta= 2d/(d+2)$ in $d$ dimensions. The other based on
Burgers equation describing anisotropic, extended clusters predicts
$\theta=d/2$ when $2\le d \le 4$. We do extensive simulations in three
dimensions to find that while $\theta$ is as predicted by ballistic
aggregation, the cluster statistics and velocity distribution differ from it.
Thus, the freely cooling granular gas fits to neither the ballistic aggregation
or a Burgers equation description.


title: Stemmers for Tamil Language: Performance Analysis

abstract:
  Stemming is the process of extracting root word from the given inflection
word and also plays significant role in numerous application of Natural
Language Processing (NLP). Tamil Language raises several challenges to NLP,
since it has rich morphological patterns than other languages. The rule based
approach light-stemmer is proposed in this paper, to find stem word for given
inflection Tamil word. The performance of proposed approach is compared to a
rule based suffix removal stemmer based on correctly and incorrectly predicted.
The experimental result clearly show that the proposed approach light stemmer
for Tamil language perform better than suffix removal stemmer and also more
effective in Information Retrieval System (IRS).


title: Relative K-area homology and applications

abstract:
  We show an Uhlenbeck type estimate for closed simply connected manifolds
which provides the existence of certain exact sequences in K-area homology.
This leads to the behavior of the K-area homology under surgery. Moreover, we
give an index theoretic obstruction to positive scalar curvature on compact
spin manifolds with boundary.


title:
Orbital structure and magnetic ordering in stoichiometric and doped
  crednerite CuMnO2

abstract:
  The exchange interactions and magnetic structure in layered system CuMnO2
(mineral crednerite) and in nonstoichiometric system Cu1.04Mn0.96O2, with
triangular layers distorted due to orbital ordering of the Mn3+ ions, are
studied by ab-initio band-structure calculations, which were performed within
the GGA+U approximation. The exchange interaction parameters for the Heisenberg
model within the Mn-planes and between the Mn-planes were estimated. We explain
the observed in-plane magnetic structure by the dominant mechanism of the
direct d-d exchange between neighboring Mn ions. The superexchange via O ions,
with 90 degree Mn-O-Mn bonds, plays less important role for the in-plane
exchange. The interlayer coupling is largely dominated by one exchange path
between the half-filled 3z^2-r^2 orbitals of Mn3+. The change of interlayer
coupling from antiferromagnetic in pure CuMnO2 to ferromagnetic in doped
material is also explained by our calculations.


title: Timing, Carrier, and Frame Synchronization of Burst-Mode CPM

abstract:
  In this paper, we propose a complete synchronization algorithm for continuous
phase modulation (CPM) signals in burst-mode transmission over additive white
Gaussian noise (AWGN) channels. The timing and carrier recovery are performed
through a data-aided (DA) maximum likelihood algorithm, which jointly estimates
symbol timing, carrier phase, and frequency offsets based on an optimized
synchronization preamble. Our algorithm estimates the frequency offset via a
one dimensional grid search, after which symbol timing and carrier phase are
computed via simple closed-form expressions. The mean-square error (MSE) of the
algorithm's estimates reveals that it performs very close to the theoretical
Cram\'er-Rao bound (CRB) for various CPMs at signal-to-noise ratios (SNRs) as
low as 0 dB. Furthermore, we present a frame synchronization algorithm that
detects the arrival of bursts and estimates the start-of-signal. We simulate
the performance of the frame synchronization algorithm along with the timing
and carrier recovery algorithm. The bit error rate results demonstrate near
ideal synchronization performance for low SNRs and short preambles.


abstract:
  The North American Nanohertz Observatory for Gravitational Waves (NANOGrav)
is a collaboration of researchers who are actively engaged in using North
American radio telescopes to detect and study gravitational waves via pulsar
timing. To achieve this goal, we regularly observe millisecond pulsars (MSPs)
with the Arecibo and Green Bank Telescopes and develop and implement new
instrumentation and algorithms for searching for and observing pulsars,
calculating arrival times, understanding and correcting for propagation delays
and sources of noise in our data, and detecting and characterizing a variety of
gravitational wave sources. We collaborate on these activities with colleagues
in the International Pulsar Timing Array (IPTA). We also educate students of
all levels and the public about the detection and study of gravitational waves
via pulsar timing.


title: Numerical evaluation of spherical GJMS determinants for even dimensions

abstract:
  The functional determinants of the GJMS scalar operators, P_{2k}, on
even-dimensional spheres are computed via Barnes multiple gamma functions
relying on the numerical availability of the digamma function. For the critical
k=d/2 case, it is necessary to calculate the Stirling moduli. The
multiplicative anomalies are given as odd polynomials in $k$ and it is
emphasised that that the Dirichlet--to--Robin factorisation, P_{2l+1}, gives
the same results as P_{2k} if k=l+1/2.The results are presented as graphs and
show a series of extrema in the effective action as k is varied in the reals.
For odd dimensions these extrema occur at integer k.

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


title:
Rank inequalities for the Heegaard Floer homology of Seifert homology
  spheres

abstract:
  We establish three rank inequalities for the reduced flavor of Heegaard Floer
homology of Seifert fibered integral homology spheres. Combining these
inequalities with the known classifications of non-zero degree maps between
Seifert fibered spaces, we prove that a map f from Y' to Y between Seifert
homology spheres yields the inequality that |deg f| rank HFred(Y) is at most
rank HFred(Y'). These inequalities are also applied in conjunction with an
algorithm of Nemethi to give a method to solve the botany problem for the
Heegaard Floer homology of these manifolds.


title: Model Reduction for Complex Hyperbolic Networks

abstract:
  We recently introduced the joint gramian for combined state and parameter
reduction [C. Himpe and M. Ohlberger. Cross-Gramian Based Combined State and
Parameter Reduction for Large-Scale Control Systems. arXiv:1302.0634, 2013],
which is applied in this work to reduce a parametrized linear time-varying
control system modeling a hyperbolic network. The reduction encompasses the
dimension of nodes and parameters of the underlying control system. Networks
with a hyperbolic structure have many applications as models for large-scale
systems. A prominent example is the brain, for which a network structure of the
various regions is often assumed to model propagation of information. Networks
with many nodes, and parametrized, uncertain or even unknown connectivity
require many and individually computationally costly simulations. The presented
model order reduction enables vast simulations of surrogate networks exhibiting
almost the same dynamics with a small error compared to full order model.


title: Agent-Based Stock Market Model with Endogenous Agents' Impact

abstract:
  The three-state agent-based 2D model of financial markets as proposed by
Giulia Iori has been extended by introducing increasing trust in the correctly
predicting agents, a more realistic consultation procedure as well as a formal
validation mechanism. This paper shows that such a model correctly reproduces
the three fundamental stylised facts: fat-tail log returns, power-law
volatility autocorrelation decay in time and volatility clustering.


title: ILC Higgs White Paper

abstract:
  The ILC Higgs White Paper is a review of Higgs Boson theory and experiment at
the International Linear Collider (ILC). Theory topics include the Standard
Model Higgs, the two-Higgs doublet model, alternative approaches to electroweak
symmetry breaking, and precision goals for Higgs boson experiments.
Experimental topics include the measurement of the Higgs cross section times
branching ratio for various Higgs decay modes at ILC center of mass energies of
250, 500, and 1000 GeV, and the extraction of Higgs couplings and the total
Higgs width from these measurements. Luminosity scenarios based on the ILC TDR
machine design are used throughout. The gamma-gamma collider option at the ILC
is also discussed.


title: The Solar Neighborhood XXX: Fomalhaut C

abstract:
  LP 876-10 is a nearby active M4 dwarf in Aquarius at a distance of 7.6 pc.
The star is a new addition to the 10-pc census, with a parallax measured via
the Research Consortium on Nearby Stars (RECONS) astrometric survey on the
Small & Moderate Aperture Research Telescope System's (SMARTS) 0.9-m telescope.
We demonstrate that the astrometry, radial velocity, and photometric data for
LP 876-10 are consistent with the star being a third, bound, stellar component
to the Fomalhaut multiple system, despite the star lying nearly 6 degrees away
from Fomalhaut A in the sky. The 3D separation of LP 876-10 from Fomalhaut is
only 0.77+-0.01 pc, and 0.987+-0.006 pc from TW PsA (Fomalhaut B), well within
the estimated tidal radius of the Fomalhaut system (1.9 pc). LP 876-10 shares
the motion of Fomalhaut within ~1 km/s, and we estimate an interloper
probability of ~10^{-5}. Neither our echelle spectroscopy nor astrometry are
able to confirm the close companion to LP 876-10 reported in the Washington
Double Star Catalog (WSI 138). We argue that the Castor Moving Group to which
the Fomalhaut system purportedly belongs, is likely to be a dynamical stream,
and hence membership to the group does not provide useful age constraints for
group members. LP 876-10 (Fomalhaut C) has now risen from obscurity to become a
rare example of a field M dwarf with well-constrained age (440+-40 Myr) and
metallicity. Besides harboring a debris disk system and candidate planet,
Fomalhaut now has two of the widest known stellar companions.


title: Zero-density estimates for L-functions attached to cusp forms

abstract:
  Let $S_k$ be the space of holomorphic cusp forms of weight $k$ with respect
to $SL_2(\mathbb{Z})$. Let $f \in S_k$ be a normalized Hecke eigenform,
$L_f(s)$ the $L$-function attached to the form $f$. In this paper we consider
the distribution of zeros of $L_f(s)$ in the strip $\sigma \leq \Re s \leq 1$
for fixed $\sigma>1/2$ with respect to the imaginary part. We study estimates
of \[ N_f(\sigma,T) = #\{\rho\in\mathbb{C} \mid L_f(\rho)=0, \sigma\ leq
\Re\rho \leq 1, 0 \leq \Im\rho \leq T} \] for $1/2 \leq \sigma \leq1$ and large
$T>0$. Using the methods of Karatsuba and Voronin we shall give another proof
for Ivi\'{c}'s method.


title:
Strain gauge fields for rippled graphene membranes under central
  mechanical load: an approach beyond first-order continuum elasticity

abstract:
  We study the electronic properties of rippled freestanding graphene membranes
under central load from a sharp tip. To that end, we develop a gauge field
theory on a honeycomb lattice valid beyond the continuum theory. Based on the
proper phase conjugation of the tight-binding pseudospin Hamiltonian, we
develop a method to determine conditions under which continuum elasticity can
be used to extract gauge fields from strain. Along the way, we resolve a recent
controversy on the theory of strain engineering in graphene: There are no
K-point dependent gauge fields. We combine this lattice gauge field theory with
atomistic calculations and find that for moderate load, the rippled graphene
membranes conform to the extruding tip without significant increase of elastic
energy. Mechanical strain is created on a membrane only after a certain amount
of load is exerted. In addition, we find that the deformation potential --even
when partially screened-- induces qualitative changes on the electronic
spectra, with Landau levels giving way to equally-spaced peaks.


title: Excitonic Magnetism in Van Vleck-type d^4 Mott Insulators

abstract:
  In Mott insulators with the t^4_{2g} electronic configuration such as of
Re^{3+}, Ru^{4+}, Os^{4+}, and Ir^{5+} ions, spin-orbit coupling dictates a Van
Vleck-type nonmagnetic ground state with angular momentum J=0, and the magnetic
response is governed by gapped singlet-triplet excitations. We derive the
exchange interactions between these excitons and study their collective
behavior on different lattices. In perovskites, a conventional Bose
condensation of excitons into a magnetic state is found, while an unexpected
one-dimensional behavior supporting spin-liquid states emerges in honeycomb
lattices, due to the bond-directional nature of exciton interactions in the
case of 90 degree d-p-d bonding geometry.


title: Upper-Expectation Bisimilarity and Real-valued Modal Logics

abstract:
  Several notions of bisimulation relations for probabilistic non-deterministic
transition systems have been considered in the literature. We consider a novel
testing-based behavioral equivalence called upper-expectation bisimilarity and
develop its theory using standard results from linear algebra and functional
analysis. We show that, for a wide class of systems, our new notion coincides
with Segala's convex bisimilarity. We develop logical characterizations in
terms of expressive probabilistic modal mu-calculi and a novel real-valued
modal logic. We prove that upper-expectation bisimilarity is a congruence for
the wide family of process algebras specified following the probabilistic GSOS
rule format.


title:
Kinematics of the Orion Trapezium Based on Diffracto-Astrometry and
  Historical Data

abstract:
  Using the novel Diffracto-Astrometry technique, we analyze 44 Hubble Space
Telescope Wide Field Planetary Camera 2 images of the Orion Trapezium (OT)
taken over a span of 12 yr (1995-2007). We measure the relative positions of
the six brighter OT components (A-F) and supplement these results with
measurements of the relative separations and position angles taken from the
literature, thus extending our analysis time base to ~200 yr. For every pair of
components we find the relative rate of separation as well as the temporal rate
of change of their position angles, which enable us to determine the relative
kinematics of the system. Component E shows a velocity larger than the OT's
escape velocity, thus confirming that it is escaping from the gravitational
pull of this system.


title:
Bifurcation diagrams of the integral mappings of a top with singular
  symmetry

abstract:
  In general case, a Hamiltonian system with three degrees of freedom
describing the motion of a rigid body in two constant fields does not admit any
symmetry groups. H.Yehia has found conditions under which the equations of
motion of the Kovelevskaya type gyrostat in such a field have, in addition to
the energy integral, an integral linear with respect to angular velocities.
Later it was noticed that this integral under the conditions of Yehia exists
for arbitrary axially symmetric gyrostat having the centers of the fields
applications in the equatorial plane. The corresponding natural mechanical
system has an $S^1$-symmetry which has a non-empty set of fixed points. Smale's
program of topological analysis can be fulfilled with some modifications
considering the singularity of the symmetry action. We construct the
bifurcation diagrams of the momentum map for a family of systems with a
singular symmetry and investigate the dependency on one essential parameter
expressing the ratio of the axial and equatorial inertia moments.


title: Hydrodynamic granular segregation induced by boundary heating and shear

abstract:
  Segregation induced by a thermal gradient of an impurity in a driven
low-density granular gas is studied. The system is enclosed between two
parallel walls from which we input thermal energy to the gas. We study here
steady states occurring when the inelastic cooling is exactly balanced by some
external energy input (stochastic force or viscous heating), resulting in a
uniform heat flux. A segregation criterion based on Navier-Stokes granular
hydrodynamics is written in terms of the tracer diffusion transport
coefficients, whose dependence on the parameters of the system (masses, sizes
and coefficients of restitution) is explicitly determined from a solution of
the inelastic Boltzmann equation. The theoretical predictions are validated by
means of Monte Carlo and molecular dynamics simulations, showing that
Navier-Stokes hydrodynamics produces accurate segregation criteria even under
strong shearing and/or inelasticity.


title: Observing Open Clusters with a Sequence of Ages with Kepler

abstract:
  We propose to observe with Kepler an age sequence of nearby uncrowded open
clusters. The current Kepler field contains very few (only 4) somewhat distant
and/or old clusters. Nearby open clusters are already well characterized from
ground- and many space-based observations. Our proposal focuses on mid and
upper main-sequence variables (main sequence and pre-main sequence gamma Dor or
delta Scuti stars, SPB/beta Cep stars, Cepheids, or yellow supergiants), having
periods of hours to days accessible by longer cadence observations.
Asteroseismology for these objects to date is limited by the number of modes
observable from the ground, difficulty in obtaining spectroscopic or
photometric mode ID for the fainter targets that have been observed by Kepler,
uncertainties in interior and initial abundances, especially for stars with
abundance anomalies, uncertainties in distance/luminosity, and lack of
knowledge of prior evolution history. The additional constraints of common age,
distance and initial abundances in clusters will place these variables in their
evolutionary context, and help unlock some of the science and reduce
uncertainties for understanding star formation and stellar evolution.


title: The TeV Blazar Measurement of the Extragalactic Background Light

abstract:
  Gamma-rays propagating through space are likely to be extinguished via
electron-positron pair production off of the ambient extragalactic background
light (EBL). The spectrum of the EBL is produced by starlight (and starlight
reprocessed by dust) from all galaxies throughout the history of the Universe.
The attenuation of 40 - 400 GeV gamma-rays has been observed by \textit{Fermi}
and used to measure the EBL spectrum over energies 1 eV -10 eV out to redshift
$z\sim 1$. Measurements of several TeV blazers are consistent with attenuation,
attributed to the EBL at redshift $z\sim 0.1$. Here we simultaneously analyze a
set of TeV blazers at $z\sim 0.1$ to measure the optical depth for 100 GeV - 10
TeV gamma-rays, which interact with EBL of energies 0.05 eV - 5 eV. Using a
suite of models for the EBL, we show that the optical depth indicated by TeV
blazar attenuation is in good agreement with the optical depths measured by
\textit{Fermi} at lower gamma-ray energies and higher redshifts.


title: Tonoli's Calabi--Yau threefolds revisited

abstract:
  We find a simple geometric construction of Tonoli's examples of Calabi--Yau
threefolds of degree 17 in complex $\mathbb{P}^6$. We prove that the rank of
the Picard group of elements of one of these families is at least $2$.


title:
Direct imaging of monovacancy-hydrogen complexes in single graphitic
  layer

abstract:
  Understanding how foreign chemical species bond to atomic vacancies in
graphene layers can advance our ability to tailor the electronic and magnetic
properties of defective graphenic materials. Here we use ultra-high vacuum
scanning tunneling microscopy (UHV-STM) and density functional theory to
identify the precise structure of hydrogenated single atomic vacancies in a
topmost graphene layer of graphite and establish a connection between the
details of hydrogen passivation and the electronic properties of a single
atomic vacancy. Monovacancy-hydrogen complexes are prepared by sputtering of
the graphite surface layer with low energy ions and then exposing it briefly to
an atomic hydrogen environment. High-resolution experimental UHV-STM imaging
allows us to determine unambiguously the positions of single missing atoms in
the defective graphene lattice and, in combination with the ab initio
calculations, provides detailed information about the distribution of
low-energy electronic states on the periphery of the monovacancy-hydrogen
complexes. We found that a single atomic vacancy where each sigma-dangling bond
is passivated with one hydrogen atom shows a well-defined signal from the
non-bonding pi-state which penetrates into the bulk with a (\sqrt 3 \times
\sqrt 3)R30^ \circ periodicity. However, a single atomic vacancy with full
hydrogen termination of sigma-dangling bonds and additional hydrogen
passivation of the extended pi-state at one of the vacancy's monohydrogenated
carbon atoms is characterized by complete quenching of low-energy localized
states. In addition, we discuss the migration of hydrogen atoms at the
periphery of the monovacancy-hydrogen complexes which dramatically change the
vacancy's low-energy electronic properties, as observed in our low-bias
high-resolution STM imaging.


title:
Permutation polynomials on F_q induced from bijective Redei functions on
  subgroups of the multiplicative group of F_q

abstract:
  We construct classes of permutation polynomials over F_{Q^2} by exhibiting
classes of low-degree rational functions over F_{Q^2} which induce bijections
on the set of (Q+1)-th roots of unity in F_{Q^2}. As a consequence, we prove
two conjectures about permutation trinomials from a recent paper by Tu, Zeng,
Hu and Li.


title:
Pre-equilibrium {\alpha}-particle emission as a probe to study
  {\alpha}-clustering in nuclei

abstract:
  A theoretical approach was developed to describe secondary particle emission
in heavy ion collisions, with special regards to pre-equilibrium
{\alpha}-particle production. Griffin's model of non-equilibrium processes is
used to account for the first stage of the compound system formation, while a
Monte Carlo statistical approach was used to describe the further decay from a
hot source at thermal equilibrium. The probabilities of neutron, proton and
{\alpha}-particle emission have been evaluated for both the equilibrium and
pre-equilibrium stages of the process. Fission and {\gamma}-ray emission
competition were also considered after equilibration. Effects due the possible
cluster structure of the projectile which has been excited during the
collisions have been experimentally evidenced studying the double differential
cross sections of p and {\alpha}-particles emitted in the E=250MeV 16O +116Sn
reaction. Calculations within the present model with different clusterization
probabilities have been compared to the experimental data.


title:
Validity of the relations between the synodic and sidereal rotation
  velocities of the Sun

abstract:
  Existing methods for conversion between synodic and sidereal rotation
velocities of the Sun are tested for validity using state of the art ephemeris
data. It is found that some of them are in good agreement with ephemeris
calculations, while the other ones show a discrepancy of almost 0.01 deg per
day. The discrepancy is attributed to a missing factor and a new corrected
relation is given.


title:
The electronic atlas of bifurcation diagrams of the Kowalevski-Yehia
  gyrostat

abstract:
  The integrable case of Kowalevski-Yehia in the dynamics of a gyrostat is
considered. We present the new way to classify the bifurcation diagrams of the
reduced systems. We find the efficiently checked existence conditions for the
critical motions on the area integral constant sections of the surfaces bearing
the 3-diagram of the complete system. The cases when these conditions
qualitatively change give the analytical expressions of the dependencies
between the area constant and the gyrostatic momentum forming the classifying
set for the two-parametric family of the reduced systems diagrams. Finally, we
present the computer system, which satisfy the given definition of the
electronic atlas.


title:
General dissipative coefficient in warm intermediate and logamediate
  inflation

abstract:
  We study a general form for the dissipative coefficient
$\Gamma(T,\phi)=C_\phi\,T^{m}/\phi^{m-1}$ in the context of warm intermediate
and logamediate inflationary universe models. We analyze these models in the
weak and strong dissipative regimes. In the slow-roll approximation, we
describe in great detail the characteristics of these models. In both regimes,
we use recent data from the WMAP nine-year data and Planck data to constrain
the parameters appearing in our models.


title: Future Sensitivity Studies for Supersymmetry Searches at CMS at 14 TeV

abstract:
  The sensitivity for CMS searches for supersymmetry is evaluated in the
context of an upgraded LHC at a center-of-mass energy of 14 TeV and an
integrated luminosity of 300 fb-1. Results for several key searches for
supersymmetry are presented including direct and gluino-mediated stop and
sbottom production and electroweak production of supersymmetric particles.


title: Radial part calculations for affine sl2 and the Heun KZB-heat equation

abstract:
  In the present paper we determine the radial part of the Casimir element for
the Lie algebra affine sl2 with respect to the Chevalley involution. The
resulting operator is identified with a blend of the Inozemtsev Hamiltonian and
the KZB-heat equation in dimension one. Moreover, it is shown how the
corresponding zonal spherical functions give rise to symmetric theta functions
and convergence is discussed. The paper takes guidance from previous work by
Etingof and Kirillov on the diagonal case.


title: Some explicit expressions concerning formal group laws

abstract:
  This paper provides some explicit expressions concerning the formal group
laws of the Brown-Peterson cohomology, the cohomology theory obtained from
Brown-Peterson theory by killing all but one Witt symbol, the Morava $K$-theory
and the Abel cohomology.


title: Geometric constructions on the algebra of densities

abstract:
  The algebra of densities $\Den(M)$ is a commutative algebra canonically
associated with a given manifold or supermanifold $M$. We introduced this
algebra earlier in connection with our studies of Batalin--Vilkovisky geometry.
The algebra $\Den(M)$ is graded by real numbers and possesses a natural
invariant scalar product. This leads to important geometric consequences and
applications to geometric constructions on the original manifold. In
particular, there is a classification theorem for derivations of the algebra
$\Den(M)$. It allows a natural definition of bracket operations on vector
densities of various weights on a (super)manifold $M$, similar to how the
classical Fr\"{o}licher--Nijenhuis theorem on derivations of the algebra of
differential forms leads to the Nijenhuis bracket. It is possible to extend
this classification from "vector fields" (derivations) on $\Den(M)$ to
"multivector fields". This leads to the striking result that an arbitrary even
Poisson structure on $M$ possesses a canonical lifting to the algebra of
densities. (The latter two statements were obtained by our student A.Biggs.)
This is in sharp contrast with the previously studied case of an odd Poisson
structure, where extra data are required for such a lifting.


title:
$V$-Integrability, Asymptotic Stability And Comparison Theorem of
  Explicit Numerical Schemes for SDEs

abstract:
  Khasminski's \cite{chas1980stochastic} showed that many of the asymptotic
stability and the integrability properties of the solutions to the Stochastic
Differential Equations (SDEs) can be obtained using Lyapunov functions
techniques. These properties are rarely inherited by standard numerical
integrators. In this article we introduce a family of explicit numerical
approximations for the SDEs and derive conditions that allow to use
Khasminski's techniques in the context of numerical approximations,
particularly in the case where SDEs have non globally Lipschitz coefficients.
  Consequently, we show that it is possible to construct a numerical scheme,
that is bounded in expectation with respect to a Lyapunov function, and/or
inherit the asymptotic stability property from the SDEs. Finally we show that
using suitable schemes it is possible to recover comparison theorem for scalar
SDEs.


title: Orderability and the Weinstein Conjecture

abstract:
  In this article we prove that the Weinstein conjecture holds for contact
manifolds $(\Sigma,\xi)$ for which $\mathrm{Cont}_0(\Sigma,\xi)$ is
non-orderable in the sense of Eliashberg-Polterovich [EP00]. More precisely, we
establish a link between orderable and hypertight contact manifolds. In
addition, we prove for certain contact manifolds a conjecture by Sandon
[San13b] on the existence of translated points in the non-degenerate case.


title: Coronal influence on dynamos

abstract:
  We report on turbulent dynamo simulations in a spherical wedge with an outer
coronal layer. We apply a two-layer model where the lower layer represents the
convection zone and the upper layer the solar corona. This setup is used to
study the coronal influence on the dynamo action beneath the surface.
Increasing the radial coronal extent gradually to three times the solar radius
and changing the magnetic Reynolds number, we find that dynamo action benefits
from the additional coronal extent in terms of higher magnetic energy in the
saturated stage. The flux of magnetic helicity can play an important role in
this context.


title:
A refined upper bound for the hyperbolic volume of alternating links and
  the colored Jones polynomial

abstract:
  We give a refined upper bound for the hyperbolic volume of an alternating
link in terms of the first three and the last three coefficients of its colored
Jones polynomial.


title: Four-coloured Spin-wave Excitations in Multiferroic Materials

abstract:
  The optical magnetoelectric effect, which is an inherent attribute of the
spin excitations in multiferroics, drastically changes their optical properties
compared to conventional materials where light-matter interaction is expressed
only by the dielectric permittivity and magnetic permeability. Our polarized
absorption experiments performed on multiferroic Ca2CoSi2O7 and Ba2CoGe2O7 in
the THz spectral range demonstrate that such magnetoeletric spin excitations
show quadrochroism, i.e. they have different colours for all the four
combinations of the two propagation directions (forward or backward) and the
two orthogonal polarizations of a light beam. We found that quadrochroism can
give rise to peculiar optical properties, such as one-way transparency and
zero-reflection of these excitations, which can open a new horizon in
photonics. One-way transparency is also related to the static magnetoelectric
phenomena, hence, these optical studies can provide guidelines for the
systematic synthesis of new materials with large dc magnetoelectric effect.


title:
Project PROMETHEUS: Design and Construction of a Radio Frequency
  Quadrupole at TAEK

abstract:
  The PROMETHEUS Project is ongoing for the design and development of a 4-vane
radio frequency quadrupole (RFQ) together with its H+ ion source, a low energy
beam transport (LEBT) line and diagnostics section. The main goal of the
project is to achieve the acceleration of the low energy ions up to 1.5 MeV by
an RFQ (352 MHz) shorter than 2 meter. A plasma ion source is being developed
to produce a 20 keV, 1 mA H+ beam. Simulation results for ion source,
transmission and beam dynamics are presented together with analytical studies
performed with newly developed RFQ design code DEMIRCI. Simulation results
shows that a beam transmission 99% could be achieved at 1.7 m downstream
reaching an energy of 1.5 MeV. As the first phase an Aluminum RFQ prototype,
the so-called cold model, will be built for low power RF characterization. In
this contribution the status of the project, design considerations, simulation
results, the various diagnostics techniques and RFQ manufacturing issues are
discussed.


title:
Topological transitions in a model with Particle-Hole symmetry,
  Pancharatnam-Berry Curvature and Dirac Points

abstract:
  We study the topology and geometry of a fermionic model on the honeycomb
lattice with spin-dependent hopping which breaks the time-reversal and
charge-conjugation symmetries but preserves their composition. We show that in
such a case the Zak phases are topological invariants that characterize the
semi-metallic state at half-filling and determine the edge state structure. As
the strength of the spin-dependent hopping varies, the model shows several
Lifshitz transitions corresponding to creation and merging of multiple Dirac
points. We discuss the possible realization of this model in cold atom systems
and propose experimental signals of detecting the Dirac points and
Pancharathnam-Berry curvature of the bands.


title: Introduction to Dirac materials and topological insulators

abstract:
  We present a short pedagogical introduction to the physics of Dirac
materials, restricted to graphene and two- dimensional topological insulators.
We start with a brief reminder of the Dirac and Weyl equations in the particle
physics context. Turning to condensed matter systems, semimetallic graphene and
various Dirac insulators are introduced, including the Haldane and the
Kane-Mele topological insulators. We also discuss briefly experimental
realizations in materials with strong spin-orbit coupling.


title: Universal extension classes for $GL_2$

abstract:
  In this note we give a new existence proof for the universal extension
classes for $GL_2$ previously constructed by Friedlander and Suslin via the
theory of strict polynomial functors. The key tool in our approach is a
calculation of Parker showing that, for suitable choices of coefficient
modules, the Lyndon--Hochschild--Serre spectral sequence for $SL_2$ relative to
its first Frobenius kernel stabilizes at the $E_2$-page. Consequently, we
obtain a new proof that if $G$ is an infinitesimal subgroup scheme of $GL_2$,
then the cohomology ring $\Hbul(G,k)$ of $G$ is a finitely-generated noetherian
$k$-algebra.


title:
Formal verification in Coq of program properties involving the global
  state effect

abstract:
  The syntax of an imperative language does not mention explicitly the state,
while its denotational semantics has to mention it. In this paper we present a
framework for the verification in Coq of properties of programs manipulating
the global state effect. These properties are expressed in a proof system which
is close to the syntax, as in effect systems, in the sense that the state does
not appear explicitly in the type of expressions which manipulate it. Rather,
the state appears via decorations added to terms and to equations. In this
system, proofs of programs thus present two aspects: properties can be verified
{\em up to effects} or the effects can be taken into account. The design of our
Coq library consequently reflects these two aspects: our framework is centered
around the construction of two inductive and dependent types, one for terms up
to effects and one for the manipulation of decorations.


title:
Lipschitz spaces generated by the Sobolev-Poincar\'e inequality and
  extensions of Sobolev functions

abstract:
  Let $d$ be a metric on $R^n$ and let $C^{m,(d)}(R^n)$ be the space of
$C^m$-function on $R^n$ whose partial derivatives of order $m$ belong to the
space $Lip(R^n;d)$. We show that the homogeneous Sobolev space
$L^{m+1}_p(R^n),p>n,$ can be represented as a union of $C^{m,(d)}(R^n)$-spaces
where $d$ belongs to a family of metrics on $R^n$ with certain "nice"
properties. This enables us in several important cases to give intrinsic
characterizations of the restrictions of Sobolev spaces to arbitrary closed
subsets of $R^n$. In particular, we generalize the classical Whitney extension
theorem for the space $C^m(R^n)$ to the case of the Sobolev space $L^m_p(R^n)$
whenever $m\ge 1$ and $p>n$.


title:
Exact quantization of the Milson potential via Romanovski-Routh
  polynomials

abstract:
  The paper re-examines Milson's analysis of the rational Sturm-Liouville (RSL)
problem with two complex conjugated regular singular points -i and +i by taking
advantage of Stevenson's complex linear-fraction transformation S(y) of the
variable y restricted to the real axis. It was explicitly demonstrated that
Stevenson's hypergeometric polynomials in a complex argument S are nothing but
Romanovsky polynomials converted from y to S. The use of Stevenson's
mathematical arguments unambiguously confirmed 'exact solvability' of the
Milson potential. It was revealed that the Milson potential has two branches
referred to as 'inside' and 'outside' depending on positions of zeros of the
so-called 'tangent polynomial' (TP) relative to the unit circle. The two
intersect along the shape-invariant Gendenshtein (Scarf II) potential. The
remarkable feature of the RCSLE associated with the inner branch of the Milson
potential (as well as its shape-invariant limit) is that it has two sequences
of nodeless almost-everywhere holomorphic (AEH) solutions which can be used as
factorization functions (FFs) for constructing new quantized-by-polynomials
potentials. In case of the Gendenshtein potential complex-conjugated
characteristic exponents (ChExps) at finite singular points of the given RCSLE
become energy independent so that each polynomial sequence turns into a finite
set of orthogonal polynomials. This confirms Quesne's conjecture [J. Math.
Phys. 54 122103 (2013)] that the 'Case III' polynomials discovered by her can
be used for constructing orthogonal polynomials of novel type.


title:
The sedimentation of flexible filaments: Trajectories, particle clouds
  and a buckling instability

abstract:
  In this fluid dynamics video we explore an array of different possible
dynamics for a flexible filament sedimenting in a viscous fluid. The
time-dependent shapes and trajectories of the filament are determined
analytically and numerically by balancing viscous, elastic and gravitational
forces in a slender-body theory for zero-Reynolds number flows. The dynamics
are characterized by a single dimensionless elasto-gravitation number. The
video shows the process of filament relaxation and reorientation, the formation
of particle clouds, and finally a buckling instability.


title: Microscopic Derivation of an Isothermal Thermodynamic Transformation

abstract:
  We obtain macroscopic isothermal thermodynamic transformations by space-time
scalings of a microscopic Hamiltonian dynamics in contact with a heat bath. The
microscopic dynamics is given by a chain of anharmonic oscillators subject to a
varying tension (external force) and the contact with the heat bath is modeled
by independent Langevin dynamics acting on each particle. After a diffusive
space-time scaling and cross-graining, the profile of volume converges to the
solution of a deterministic diffusive equation with boundary conditions given
by the applied tension. This defines an irreversible thermodynamic
transformation from an initial equilibrium to a new equilibrium given by the
final tension applied. Quasi static reversible isothermal transformations are
then obtained by a further time scaling. Heat is defined as the total flux of
energy exchanged between the system and the heat bath. Then we prove that the
relation between the limit heat, work, free energy and thermodynamic entropy
agree with the first and second principle of thermodynamics.

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


title:
Determination of the top quark mass circa 2013: methods, subtleties,
  perspectives

abstract:
  We present an up-to-date overview of the problem of top quark mass
determination. We assess the need for precision in the top mass extraction in
the LHC era together with the main theoretical and experimental issues arising
in precision top mass determination. We collect and document existing results
on top mass determination at hadron colliders and map the prospects for future
precision top mass determination at e+e- colliders. We present a collection of
estimates for the ultimate precision of various methods for top quark mass
extraction at the LHC.


title: Efficient simulation of the Ginibre point process

abstract:
  The Ginibre point process is one of the main examples of deter- minantal
point processes on the complex plane. It forms a recurring model in stochastic
matrix theory as well as in pratical applications. However, this model has
mostly been studied from a probabilistic point of view in the fields of
stochastic matrices and determinantal point processes, and thus using the
Ginibre process to model random phenomena is a topic which is for the most part
unexplored. In order to obtain a determinantal point process more suited for
simulation, we introduce a modified version of the classical kernel. Then, we
compare three different methods to simulate the Ginibre point process and
discuss the most efficient one depending on the application at hand.


title: Balls into bins via local search: cover time and maximum load

abstract:
  We study a natural process for allocating m balls into n bins that are
organized as the vertices of an undirected graph G. Balls arrive one at a time.
When a ball arrives, it first chooses a vertex u in G uniformly at random. Then
the ball performs a local search in G starting from u until it reaches a vertex
with local minimum load, where the ball is finally placed on. Then the next
ball arrives and this procedure is repeated. For the case m = n, we give an
upper bound for the maximum load on graphs with bounded degrees. We also
propose the study of the cover time of this process, which is defined as the
smallest m so that every bin has at least one ball allocated to it. We
establish an upper bound for the cover time on graphs with bounded degrees. Our
bounds for the maximum load and the cover time are tight when the graph is
transitive or sufficiently homogeneous. We also give upper bounds for the
maximum load when m > n.


title: Introducing Enriched Concrete Syntax Trees

abstract:
  In our earlier research an area of consistent and systematic application of
software metrics was explored. Strong dependency of applicability of software
metrics on input programming language was recognized as one of the main
weaknesses in this field. Introducing enriched Concrete Syntax Tree (eCST) for
internal and intermediate representation of the source code resulted with step
forward over this weakness. In this paper we explain innovation made by
introducing eCST and provide idea for broader applicability of eCST in some
other fields of software engineering.


title:
Spectral Approach to the Relativistic Inverse Stellar Structure Problem
  II

abstract:
  The inverse stellar structure problem determines the equation of state of the
matter in stars from a knowledge of their macroscopic observables (e.g. their
masses and radii). This problem was solved in a previous paper by constructing
a spectral representation of the equation of state whose stellar models match a
prescribed set of macroscopic observables. This paper improves and extends that
work in two significant ways: i) The method is made more robust by accounting
for an unexpected feature of the enthalpy based representations of the
equations of state used in this work. After making the appropriate
modifications, accurate initial guesses for the spectral parameters are no
longer needed so Monte-Carlo techniques can now be used to ensure the best fit
to the observables. ii) The method is extended here to use masses and tidal
deformabilities (which will be measured by gravitational wave observations of
neutron-star mergers) as the macroscopic observables instead of masses and
radii. The accuracy and reliability of this extended and more robust spectral
method is evaluated in this paper using mock data for observables from stars
based on 34 different theoretical models of the high density neutron-star
equation of state. In qualitative agreement with earlier work, these tests
suggest the high density part of the neutron-star equation of state could be
determined at the few-percent accuracy level using high quality measurements of
the masses and radii (or masses and tidal deformabilities) of just two or three
neutron stars.


title:
Accelerator system for the PRISM based muon to electron conversion
  experiment

abstract:
  The next generation of lepton flavor violation experiments need high
intensity and high quality muon beams. Production of such beams requires
sending a short, high intensity proton pulse to the pion production target,
capturing pions and collecting the resulting muons in the large acceptance
transport system. The substantial increase of beam quality can be obtained by
applying the RF phase rotation on the muon beam in the dedicated FFAG ring,
which was proposed for the PRISM project.This allows to reduce the momentum
spread of the beam and to purify from the unwanted components like pions or
secondary protons. A PRISM Task Force is addressing the accelerator and
detector issues that need to be solved in order to realize the PRISM
experiment. The parameters of the required proton beam, the principles of the
PRISM experiment and the baseline FFAG design are introduced. The spectrum of
alternative designs for the PRISM FFAG ring are shown. Progress on ring main
systems like injection and RF are presented. The current status of the study
and its future directions are discussed.


title:
The vmf90 program for the numerical resolution of the Vlasov equation
  for mean-field systems

abstract:
  The numerical resolution of the Vlasov equation provides complementary
information with respect to analytical studies and forms an important research
tool in domains such as plasma physics. The study of mean-field models for
systems with long-range interactions is another field in which the Vlasov
equation plays an important role. We present the vmf90 program that performs
numerical simulations of the Vlasov equation for this class of mean-field
models with the semi-Lagrangian method.


title:
Variability of the accretion disk of V926 Sco inferred from tomographic
  analysis

abstract:
  We present phase-resolved spectroscopic observations of the low-mass X-ray
binary V926 Sco (4U 1735-44), covering the orbital period of 0.23d, obtained
with the Walter Baade 6.5m Magellan Telescope at the Las Campanas Observatory
in June 2010 and June 2011. We use H$\alpha$ radial velocities to derive a
systemic velocity of -109 $\pm$ 4 km s$^{-1}$. The FWHM of the lines observed
in common with previous authors are significantly lower during our observations
suggesting much reduced velocities in the system. The equivalent width of the
Bowen fluorescence lines with respect to He II $\lambda$4686 are factors of two
or more lower during our observations in comparison to those previously
reported for the system, suggesting reduced irradiation of the secondary.
Doppler and modulation tomography of H$\alpha$ and He II $\lambda$4686 show
assymmetric emission that can be attributed to a bulge in the accretion disk,
as inferred from He II observations by previous authors. The X-ray fluxes from
the source at times concurrent with the optical observations are significantly
lower during our observations than during optical observations taken in 2003.
We suggest that the system is in a lower accretion state compared to earlier
observations; this explains both the lower velocities observed from the disk
and the reduction of emission due to Bowen fluorescence detected from the
secondary.


title:
Exact and Stable Covariance Estimation from Quadratic Sampling via
  Convex Programming

abstract:
  Statistical inference and information processing of high-dimensional data
often require efficient and accurate estimation of their second-order
statistics. With rapidly changing data, limited processing power and storage at
the acquisition devices, it is desirable to extract the covariance structure
from a single pass over the data and a small number of stored measurements. In
this paper, we explore a quadratic (or rank-one) measurement model which
imposes minimal memory requirements and low computational complexity during the
sampling process, and is shown to be optimal in preserving various
low-dimensional covariance structures. Specifically, four popular structural
assumptions of covariance matrices, namely low rank, Toeplitz low rank,
sparsity, jointly rank-one and sparse structure, are investigated, while
recovery is achieved via convex relaxation paradigms for the respective
structure.
  The proposed quadratic sampling framework has a variety of potential
applications including streaming data processing, high-frequency wireless
communication, phase space tomography and phase retrieval in optics, and
non-coherent subspace detection. Our method admits universally accurate
covariance estimation in the absence of noise, as soon as the number of
measurements exceeds the information theoretic limits. We also demonstrate the
robustness of this approach against noise and imperfect structural assumptions.
Our analysis is established upon a novel notion called the mixed-norm
restricted isometry property (RIP-$\ell_{2}/\ell_{1}$), as well as the
conventional RIP-$\ell_{2}/\ell_{2}$ for near-isotropic and bounded
measurements. In addition, our results improve upon the best-known phase
retrieval (including both dense and sparse signals) guarantees using PhaseLift
with a significantly simpler approach.

categories: cs.IT cs.LG math.IT math.NA math.ST stat.ML stat.TH


title: On the Rotation of the Magnetic Field Across the Heliopause

abstract:
  There was an expectation that the magnetic field direction would rotate
dramatically across the heliopause (HP). This rotation was used as one of the
criteria to determine if Voyager 1 (V1) had crossed the HP. Recently the
Voyager team concluded that V1 crossed into interstellar space last year
(Gurnett et al. 2013). The question is then why there was no significant
rotation in the direction of the magnetic field across the HP (Burlaga et al.
2013). Here we present simulations that reveal that strong rotations in the
direction of the magnetic field at the HP at the location of V1 (and Voyager 2)
are not expected. The solar magnetic field strongly affects the drapping of the
interstellar magnetic field (BISM) around the HP. BISM twists as it approaches
the HP and acquires a strong T component (east-west). The strong increase in
the T component occurs where the interstellar flow stagnates in front of the
HP. At this same location the N component BN is significantly reduced. Above
and below the neighboring interstellar magnetic field lines also twist into the
T direction. This behavior occurs for a wide range of orientations of BISM.
Thus, the BN component at the V1 location and the associated angle delta=a
sin(BN/B) are small (around 10-20 degrees), as seen in the observations
(Burlaga et al. 2013). Only after some significant distance outside the HP, is
the direction of the interstellar field distinguishably different from that of
the Parker spiral.


title:
A measurement of the turbulence-driven density distribution in a
  non-star-forming molecular cloud

abstract:
  Molecular clouds are supersonically turbulent. This turbulence governs the
initial mass function and the star formation rate. In order to understand the
details of star formation, it is therefore essential to understand the
properties of turbulence, in particular the probability distribution of density
in turbulent clouds. We present formaldehyde volume density measurements of a
non-star-forming cloud along the line of sight towards W49A. We use these
measurements in conjunction with total mass estimates from 13CO to infer the
shape of the density probability distribution function. This method is
complementary to measurements of turbulence via the column density distribution
and should be applicable to any molecular cloud with detected CO. We show that
turbulence in this cloud is probably compressively driven, with a
compressive-to-total Mach number ratio $b = \mathcal{M}_C/\mathcal{M}>0.4$. We
measure the standard deviation of the density distribution, constraining it to
the range $1.5 < \sigma_s < 1.9$ assuming that the density is lognormally
distributed. This measurement represents an essential input into star formation
laws. The method of averaging over different excitation conditions to produce a
model of emission from a turbulent cloud is generally applicable to optically
thin line observations.


title:
RoboRun: A gamification approach to control flow learning for young
  students with TouchDevelop

abstract:
  This demo paper introduces young students to writing code in a touch enabled
interactive maze game. Problem-based learning is given a gamified approach to
learning, while simultaneously introducing the TouchDevelop platform to build
basic first control flow algorithms and to learn about ordering and loops in
conditional statements.


title:
Full Control of Magnetism in Manganite Bilayer by Ferroelectric
  Polarization

abstract:
  An oxide heterostructure made of manganite bilayers and ferroelectric
perovskites is predicted to lead to the full control of magnetism when
switching the ferroelectric polarizations. By using asymmetric polar interfaces
in the superlattices, more electrons occupy the Mn layer at the $n$-type
interface side than at the $p$-type side. This charge disproportionation can be
enhanced or suppressed by the ferroelectric polarization. Quantum model and
density functional theory calculations reach the same conclusion: a
ferromagnetic-ferrimagnetic phase transition with maximal change $>90%$ of the
total magnetization can be achieved by switching the polarization's direction.
This function is robust and provides full control of the magnetization's
magnitude, not only its direction, via electrical methods.


title:
The p-Laplace equation in domains with multiple crack section via pencil
  operators

abstract:
  The p-Laplace equation
  $$ \n \cdot (|\n u|^n \n u)=0 \whereA n>0, $$ in a bounded domain $\O \subset
\re^2$, with inhomogeneous Dirichlet conditions on the smooth boundary $\p \O$
is considered. In addition, there is a finite collection of curves
  $$\Gamma = \Gamma_1\cup...\cup\Gamma_m \subset \O, \quad \{on which we assume
homogeneous Dirichlet boundary conditions} \quad u=0, $$ modeling a multiple
crack formation, focusing at the origin $0 \in \O$. This makes the above
quasilinear elliptic problem overdetermined. Possible types of the behaviour of
solution $u(x,y)$ at the tip 0 of such admissible multiple cracks, being a
"singularity" point, are described, on the basis of blow-up scaling techniques
and a "nonlinear eigenvalue problem". Typical types of admissible cracks are
shown to be governed by nodal sets of a countable family of nonlinear
eigenfunctions, which are obtained via branching from harmonic polynomials that
occur for $n=0$. Using a combination of analytic and numerical methods,
saddle-node bifurcations in $n$ are shown to occur for those nonlinear
eigenvalues/eigenfunctions.


title:
Strong shape dependence of the Morin transition in alpha-Fe2O3
  single-crystalline nanostructures

abstract:
  Single-crystalline alpha-Fe2O3 nanorings (short nanotubes) and nanotubes were
synthesized by a hydrothermal method. High-resolution transmission electron
microscope and selected-area electron diffraction confirm that the axial
directions of both nanorings and nanotubes are parallel to the crystalline
c-axis. What is intriguing is that the Morin transition occurs at about 210 K
in the short nanotubes with a mean tube length of about 115 nm and a mean outer
diameter of 169 nm while it disappears in the nanotubes with a mean tube length
of about 317 nm and a mean outer diameter of 148 nm. Detailed analyses of
magnetization data, x-ray diffraction spectra, and room-temperature Mossbauer
spectra demonstrate that this very strong shape dependence of the Morin
transition is intrinsic to hematite. We can quantitatively explain this
intriguing shape dependence in terms of opposite signs of the surface magnetic
anisotropy constants in the surface planes parallel and perpendicular to the
c-axis (that is, K_parallel = -0.37 erg/cm^2 and K_perp = 0.42 erg/cm^{2}).


title:
The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf
  Galaxies

abstract:
  We present spectroscopic metallicities of individual stars in seven gas-rich
dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same
mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the
Milky Way and M31: Z_* ~ M_*^(0.30 +/- 0.02). The uniformity of the relation is
in contradiction to previous estimates of metallicity based on photometry. This
relationship is roughly continuous with the stellar mass-stellar metallicity
relation for galaxies as massive as M_* = 10^12 M_sun. Although the average
metallicities of dwarf galaxies depend only on stellar mass, the shapes of
their metallicity distributions depend on galaxy type. The metallicity
distributions of dIrrs resemble simple, leaky box chemical evolution models,
whereas dSphs require an additional parameter, such as gas accretion, to
explain the shapes of their metallicity distributions. Furthermore, the
metallicity distributions of the more luminous dSphs have sharp, metal-rich
cut-offs that are consistent with the sudden truncation of star formation due
to ram pressure stripping.


title: Menus for Feeding Black Holes

abstract:
  Black holes are the ultimate prisons of the Universe, regions of spacetime
where the enormous gravity prohibits matter or even light to escape to
infinity. Yet, matter falling toward the black holes may shine spectacularly,
generating the strongest source of radiation. These sources provide us with
astrophysical laboratories of extreme physical conditions that cannot be
realized on Earth. This chapter offers a review of the basic menus for feeding
matter onto black holes and discusses their observational implications.


title: The Mass-Metallicity-SFR Relation at z >~ 2 with 3D-HST

abstract:
  We present new accurate measurements of the physical properties of a
statistically significant sample of 103 galaxies at z~2 using near-infrared
spectroscopy taken as part of the 3D-HST survey. We derive redshifts,
metallicities and star formation rates (SFRs) from the [OII], [OIII] and Hbeta
nebular emission lines and exploit the multi-wavelength photometry available in
CANDELS to measure stellar masses. We find the mass-metallicity relation (MZR)
derived from our data to have the same trend as previous determinations in the
range 0<z<3, with lower mass galaxies having lower metallicities. However we
find an offset in the relation compared to the previous determination of the
z~2 MZR by Erb et al. 2006b, who measure metallicities using the [NII]/Halpha
ratio, with metallicities lower at a given mass. Incorporating our SFR
information we find that our galaxies are offset from the Fundamental
Metallicity Relation (FMR) by ~0.3 dex. We investigate the photoionization
conditions and find that our galaxies are consistent with the elevated
ionization parameter previously reported in high-redshift galaxies. Using the
BPT diagram we argue that, if this is the case, metallicity indicators based on
[NII] and Halpha may not be consistent with the ones obtained via oxygen lines
and Hbeta. Using a recent determination of the theoretical evolution of the
star forming sequence in the BPT diagram we convert our measured [OIII]/Hbeta
line ratios to [NII]/Halpha ratios. From the [NII]/Halpha ratio we infer
systematically higher metallicities in better agreement with the FMR. Our
results thus suggest the evolution of the FMR previously reported at z~2-3 may
be an artifact of the differential evolution in metallicity indicators, and
caution against using locally calibrated metallicity relations at high redshift
which do not account for evolution in the physical conditions of star-forming
regions.